Quest 1(2)

SCIENCE FOR SOUTH AFRICA

ISSN 1729-830X

VOLUME 1 • NUMBER 2 • 2004 R20 incl. VAT

ACADEMY OF SCIENCE OF SOUTH AFRICA

Cover stories

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Biotech for forests & food

Jan Perold Science and industry work together 12

Diamonds ancient & modern

Contents

Alan Rice Are diamonds really ‘forever’? plus a Fact File

16

VOLUME 1 • NUMBER 2 • 2004

Cultivating health & wealth

Tony Dold and Michelle Cocks Conserving plants for traditional medicine

Regulars 9

22

Science news

South Africa’s Southern Ocean islands

Saturn’s secrets; Messenger off to Mercury; Death throes of stars (p.15) • Hamburgers destroy forests; Birds in decline; Wake up and smell the coffee; Kyoto in fashion (p.32) • See-through progress; How heavy oil was made; Gender (e)quality? (p.41) • Centres of scientific excellence (p.45) • Laser lights up layers; New chips for old (p.46) • Francis Crick: revolutionary (p.47)

■ Sub-Antarctic eco-labs Valdon Smith Climate change helps invaders on Marion Island ■ Overcoming catastrophe Valdon Smith and Marthan Bester How cats destroy island ecosystems ■ How South Africa got its islands Valdon Smith The annexation of the Prince Edward Islands

Careers Work in biotechnology

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The S&T Tourist The Johannesburg Zoo Visit the zoo for year-round recreation, conservation, and education Computing and technology

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Googling made easy – Eldene Eyssell

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High tech for industry – Leon Liebenberg

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QUEST interview SA science: the bigger picture – Rob Adam Mathematics

Features 10

34

Mathematics in everyday life – George Ellis

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Measuring up Blinks & shakes, flocks & drops

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Your QUESTions answered Calculating cousins

40

Viewpoint Is science to be trusted? – Graham Baker

42

Books Figs of southern & south-central Africa,

by John and Sandra Burrows • and other titles

Away with tooth decay

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Letters to QUEST Conservation is no picnic

Peter Cleaton-Jones Healthy teeth for South Africans

45

Crossword puzzle

46

Diary of Events

47

ASSAf news

48

Subscription form • Back page science

Olympic heights Some of the science behind the medals

30

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he quest for excellence goes on in labs and research institutions, and our scientists keep breaking new ground.

But the average South African hears very little about these successes.

It’s not easy for interested general readers to access science and technology. Findings appear in the professional literature in dense, specialized language that is hard to follow for people without the right scientific background.

Also, methods of investigation are complex and technically sophisticated. It’s difficult to keep up with new ways of examining the universe and processing data – from the grandest phenomena of outer space to matter that’s explored on the diminutive nanoscale.

The gap of understanding between scientists and the public can be overwhelming.

When QUEST was launched we tried to find out what people wanted to know about science, so in the first issue there was a survey form. By completing and returning it, readers could help to shape QUEST’s future. Answers came from about 50 people, many of whom work with science in public schools in cities, townships, and country areas. Their comments told us that QUEST is a Good Thing and that, all round South Africa, there are readers who really care about hearing from our researchers about their discoveries and achievements.

It’s a great compliment to scientists who wrote for QUEST’s first issue that readers found the stories ‘friendly’ and accessible. This only happens when researchers are willing to write not just as scientists but also as ordinary people with lives that touch the world of their readers. At the same time readers want to be sure they’re getting the accuracy and nuance that excellent science is all about.

Excellence is at the heart of government’s national strategy to make South Africa’s science and technology equal to the world’s best and to maintain and grow its successes. In mid-2004, the Department of Science and Technology launched its first six centres of excellence (p.45). Managed by the National Research Foundation, they focus on six research areas of national importance. This issue of QUEST features two of them – the biotechnology conducted at the Forestry and Agriculture Biotechnology Institute (opposite page) and the results of invasive biology on our sub-Antarctic territories, the Prince Edward Islands (p.22).

Readers’ suggestions have pointed the way in our choice of topics. Gemstones sparkle in a new examination of the age and formation of diamonds (p.12), and conservation is the key to sustaining our supplies of traditional medicinal plants (p.16). There’s a medical focus on healthy teeth (p.30) and watchpoints for sporting heroes (p.10). There are news items about science and technology around the world and hot tips for Internet googlers. Scientific debate has begun with our first set of readers’ letters and more could follow from questions for scientists to answer. Keep reading and questioning our science and technology – and please keep sending QUEST your comments.

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A female Sirex wasp laying her eggs in a tree (see article p.3).

Photograph: Courtesy of Ronald Heath, Forestry and Agricultural Biotechnology Institute (FABI)

SCIENCE FOR SOUTH AFRICA

ISSN 1729-830X

Editor Elisabeth Lickindorf Assistant Editor Eldene Eyssell Editorial Board Wieland Gevers (University of Cape Town) (Chair) Graham Baker (South African Journal of Science) Anusuya Chinsamy-Turan (University of Cape Town) George Ellis (University of Cape Town) Jonathan Jansen (University of Pretoria) Colin Johnson (Rhodes University) Correspondence and The Editor enquiries PO Box 1011, Melville 2109 South Africa Tel./fax: (011) 673 3683 e-mail: editor.quest@iafrica.com (For more information visit www.assaf.co.za) Business Manager Neville Pritchard Advertising and Neville Pritchard Subscription enquiries PO Box 5700 Weltevreden Park 1715 South Africa Tel.: (011) 678 7093 Fax: (011) 673 3683 Cell: 083 408 3286 e-mail: pritchardn@mweb.co.za Copyright © 2004 Academy of Science of South Africa Published quarterly by the Academy of Science of South Africa (ASSAf) PO Box 72135, Lynnwood Ridge 0040, South Africa (011) 673 3683 Permissions Fax: e-mail: editor.quest@iafrica.com (011) 678 7093 Back issues Tel.: Fax: (011) 673 3683 e-mail: pritchardn@mweb.co.za Subscription rates (4 issues and postage) (For subscription form, other countries, see p.48.)

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The views expressed in this magazine are not necessarily those of the publisher.

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Elisabeth Lickindorf Editor – QUEST: Science for South Africa

Join QUEST’s knowledge sharing activities ■

Write letters for our regular Letters column – e-mail or fax your letter to The Editor. (Write QUEST LETTER in the subject line.)

■ Ask science and technology (S&T) questions for specialist members of the Academy of Science to answer in our regular S&T Questions and Answers column – e-mail or fax your questions to The Editor and win a prize. (Write S&T QUESTION in the subject line.)

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Science writer Jan Perold explains ways in which science and industry work as biotech partners to help South Africa grow healthy forests and food crops.

What is biotechnology?

DNA sequencing, gene mapping to identify the DNA regions associated with particular traits or functions, gene cloning, and using restriction enzymes to cut and splice together sections of DNA. They have brought wide-ranging applications including ‘recombinant DNA technology’ or ‘genetic engineering’, which involves isolating a gene that confers a specific trait in one organism and transferring it to another organism.

Forestry and agriculture in South Africa benefit in many ways from biotechnology. This area of science is carefully regulated for safety and, given the poverty and food shortages on our continent, it can help us to produce prosperity and, quite literally, food for Africa. ▲ ▲

For many people ‘biotechnology’ means “genetically modified foods”, but biotechnology is older and wider than that. Broadly defined, it is “the use of living organisms (or their components or derivatives) to produce useful things”.

When we use bacteria or yeasts and other fungi to leaven dough or to turn grape juice into wine, malt and hops into beer, milk into cheese or yoghurt, or soil into compost, we practise the oldest form of biotechnology. When scientists culture cells or tissues to produce antibiotics, enzymes, and vitamins, or breed plants and animals for desirable characteristics, they’re also practising biotechnology.

Since the 1970s, new techniques have been developed for manipulating DNA, including DNA fingerprinting, reading genetic messages through

For more on biotechnology visit www.arc.agric.za/main/biotech.htm and www.swisslifesciences.ch/page/definitions.php

Centre of Excellence at FABI In June 2004, Minister Mosibudi Mangena launched the Department of Science and Technology (DST) Centre of Excellence in Tree Health Biotechnology at FABI (Forestry and Agricultural Biotechnology Institute).

Based at the University of Pretoria, and under the leadership of Professor Mike Wingfield, FABI combines education with a focus on problem solving and R&D (research and development) for industry through its cutting-edge but expensive research in the biological sciences. Scientists use high-tech equipment to probe life at the fundamental level of DNA, and high-level computing power to analyse data. Providing crucial R&D expertise for local industry serves the country’s needs and helps to finance the institute’s scientific investigations.

South Africa’s forestry and agriculture industries both need biotechnology research to stay internationally competitive. DNA fingerprinting, for instance, is often the only way to identify accurately the organisms that cause plant diseases, while genetic engineering opens up vast possibilities for developing disease-resistant crops.

Industry’s financial support for FABI in exchange for scientific services enables the institute to build and maintain the infrastructure for world-class academic research and to develop the country’s future scientists. As part of a higher education institution, FABI trains the next generation of microbiologists, plant pathologists, entomologists, biochemists, and geneticists. Students work with state-of-the-art equipment and work on real problems, side by side with foresters and farmers. In six years, FABI has grown from 50 to 150 academic staff, postgraduate students, postdoctoral fellows, research visitors, and core support staff. In the two years to May 2003, apart from many other professional contributions, its scientists published 94 research articles.

On 25 May 2004, FABI’s new building, FABI Square/Bioinformatics, was opened to house its growing research activities and its expanding collaborations with institutions in South Africa and abroad.

For FABI, ivory-tower research is a thing of the past. The largest of its wide-ranging research programmes is the Tree Protection Co-operative Programme (TPCP). Others include the Banana Disease and Citrus Research programmes, the Forest Molecular Genetics Programme, and the work of the Molecular Plant Physiology Group and the groups focusing on cereal and fungal genomics, mango research, and molecular plant–pathogen interactions.

For more about FABI visit http://fabinet.up.ac.za For DST centres of excellence visit www.nrf.ac.za and see p.45.

What tree disease can look like. Above: Mushrooms are the fruiting bodies of fungi – the cause of many tree diseases. Middle: Cross-section of a pine stem showing Cryphonectria infection.

Right: A tree killed by a fungus in the genus Cryphonectria.

Photographs: Courtesy of Mike Wingfield

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Diplodia spores inside a fruiting body.

Photograph: Courtesy of Marieka Gryzenhout

Globetrotting critters that menace forests The term ‘global village’ conjures up a world without borders, but people and products moving from country to country can carry other living things with them. Sometimes this is deliberate – when, for example, exotic trees are cultivated in plantations to prevent the logging of old-growth native forests for timber or pulp mills. Sometimes it happens by accident – when pests and diseases that attack such trees are unintentionally introduced with them. Both kinds of event can damage natural ecosystems that have evolved a delicate balance over countless millennia. Both need to be researched and controlled.

Species that cause plant disease need to be accurately identified, for instance. Then, to ensure that new pests and pathogens are not introduced, we need to know the strains and varieties that exist within individual species. Because there is often great similarity among members of the same species (and even among members of different species), one sure way to gain the knowledge we need is to use DNA-based techniques.

Two examples of DNA-based FABI research that has helped to control disease and pests in pine forests are investigations into Diplodia shoot blight and die-back – an important

Diplodia – causes and symptoms Diplodia shoot blight and die-back ■ is a disease of pine trees caused by the fungus known as either Sphaeropsis sapinea or Diplodia pinea (name changes occur because mycologists – scientists who work with fungi – struggle to find the most appropriate classification for their objects of study); ■ is native to the northern hemisphere, and came into South Africa probably as a stowaway on pine seeds imported during the 20th century; ■ lives as mycelium (a network of filaments similar to bread mould) inside the shoots, bark, cones, or litter of pines.

It forms fruiting bodies, or pycnidia (small, black, flask-like cavities), on the surface of dead tissues, which exude spores whenever it rains during the trees’ growing season. The spores may invade succulent shoots, or they may infect woody tissue through wounds caused by hail, insects, or human activity.

Diplodia infection has three distinct symptoms: ■ Shoot blight. Young, growing shoots turn brown and become stunted or curled. Black fruiting bodies may be present on dead needles or shoot tissue. Such infections can occur in trees of all ages.

■ Cankers. Oblong, sunken areas of dead tissue form on branches or stems, and are often accompanied by copious resin flow on the outer bark. Cankers result from the infection of woody tissue following mechanical damage. If the bark is removed, olive-green streaking and brown, pitch-soaked wood become visible. Where a canker advances far enough to girdle an entire stem, the part of the tree above the canker dies.

■ Collar rot. Blue or black discolouration of wood in the root collar zone (i.e. the area of transition between stem and root at the ground line) indicates that this area is infected by Diplodia. The fungus may live on the bark in the root collar area without causing significant harm to a tree, but if the host becomes stressed because of drought, excessive water, or infection by other diseases, the fungus can kill the whole tree.

For more on S. sapinea, consult J. de Wet, M.J. Wingfield, T.A. Coutinho, and B.D. Wingfield, “Characterization of Sphaeropsis sapinea isolates from South Africa, Mexico, and Indonesia”, Plant Disease, vol. 84 (2000), pp.151–156.

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disease of pine trees in South Africa – and into the combined destructiveness of the Sirex woodwasp and the fungus Amylostereum areolatum (see boxes).

Diplodia threatens pines Diplodia shoot blight and die-back is caused by an opportunistic pathogen (Diplodia pinea) that tends to attack pines growing under stress. In South Africa it causes millions of rands’ worth of losses each year, because so many of our pine plantations consist of the species Pinus patula and P. radiata – both of which are nonindigenous exotics, highly susceptible to Diplodia infection. Frequent hail damage erodes these trees’ defences against the fungus even more.

South Africa, like other countries, has strict quarantine measures to prevent exotic plant diseases from being introduced. But because Diplodia pinea had already occurred locally, quarantine measures aimed at this pathogen were not given high priority.

Research by Treena Burgess, Juanita de Wet, and others at FABI, however, revealed two important facts about D. pinea. First, South Africa had unknowingly become inundated with new introductions of the fungus. Second, if these introductions continue, the consequences for the forestry industry could be very costly.

What kind of scientific detection led the researchers to these conclusions?

Comparing strains Using DNA sequences and population genetic markers, the researchers compared isolates of the fungus collected in South Africa and those from other countries such as Indonesia, where pines (and probably the fungus, too) are native.

Because a species’ diversity is normally higher in regions where it has been present for the longest time, they expected more diversity in the Indonesian samples. Surprisingly, however, they found significantly higher diversity in the South African samples.

To understand why this result was unusual, consider the evolution of orally transmitted stories. As successive generations of parents tell a story to their children, some of them make small changes to the story line. The children pass on to their own children these modified versions – with perhaps further small alterations.

As a result, older stories tend to have a greater number of variations, and we find more versions of the same story in those regions where it has been told and retold over the longest time (unless the story becomes ‘standardized’ through a book or film).

The gene pool of a population or species follows the same process. Small genetic variations or mutations accumulate over generations, and the genetic diversity of an organism is normally higher in its native range (where it has been present for the longest time) than in areas where it has recently been introduced.

If the genetic profiles of exotics tend to be more uniform than those of natives, why would South African isolates of D. pinea display greater diversity than those from Indonesia? The only reasonable explanation was that the fungus had come to South Africa from many different locations – perhaps these introductions occurred hundreds or even thousands of times during the 20th century.

Discovering the invisible traffic in D. pinea was just the start. Further research showed the FABI scientists that, although the various strains of the fungus look the same physically, their impact on trees is very different.

Three strains of the fungus have been identified: Morphotypes A, B, and C. Morphotype C – by far the most virulent – is not yet present in South Africa. The significant losses of pine trees in this country are due to its milder cousin, Morphotype A. If Morphotype C appeared here, however, forestry would be severely damaged. So quarantine procedures need to be modified to take into account genetic differences existing within the species.

In this way we can avert a potentially calamitous fungal invasion.

Left: Sirex larvae.

Below left: Brown patches show Sirex damage in a pine plantation.

Photographs: Courtesy of Ronald Heath

Sirex woodwasp – a new invader

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Like Diplodia, the woodwasp Sirex noctilio and its fungal associate Amylostereum areolatum are native to the northern hemisphere. On their home ground, a natural balance exists between the insect–fungus complex, its natural parasites, and host trees. But, when introduced into southern hemisphere countries, they kill trees extensively in exotic pine plantations. The pest appeared in New Zealand early in the 20th century, in Tasmania in the 1950s, in Australia in 1961, and in South America in the 1980s. Then it appeared in South Africa in 1994, first in the Cape Province only, but now also in KwaZuluNatal, and it’s spreading northward at an alarming rate.

The distances between all these countries are too great for the wasps to have travelled under their own steam, so they probably arrived by way of imported wood products with Sirex larvae hidden inside. Busier international trade gives the wasps more hitchhiking opportunities, which helps to explain why the time intervals between new introductions are getting shorter.

North-to-south or south-to-south?

What route did this new invasion take? Did the wasp–fungus complex come independently into each country from the northern hemisphere, or did it spread over the southern hemisphere after an initial introduction from the north? The answer is crucial for pine-growing countries in the south, so that they can design protective quarantine measures against wood imports from the specific high-risk countries.

Earlier studies had shown that A. areolatum in the southern hemisphere seldom reproduces

(Left) Male and (right) female Sirex wasp.

Photographs: Courtesy of Brett Hurley

Deadly woodwasp–fungus combination Deadly to exotic pine trees is a combined attack by the Sirex woodwasp (Sirex noctilio) and Amylostereum areolatum, a fungus that lives in a highly evolved symbiotic relationship with the wasp. Female Sirex wasps drill holes one or two centimetres into the wood of a tree, and inject toxic mucous and spores of the fungus. If a tree is suitable, one or two eggs are also laid nearby. The mucous blocks the tree’s natural defences against fungal infection, and the fungus grows into the wood.

A tree attacked successfully in this way dies within a few weeks or months. Then the fungus grows throughout the dead tree, while the Sirex eggs hatch and the emerging grubs bore into the wood and feed on the fungus.

The grubs can grow to a length of up to 5 cm and a diameter of over 1 cm. They normally pupate at the end of the first year, although this can be delayed by one or more years if the wood is not dry enough. A few weeks later, the adult Sirex wasps emerge and chew their way out of the tree, leaving perfectly round holes between 0.5 and 1 cm in diameter. Because they have been living in an environment saturated with the fungus, the wasps enter adulthood with the fungal spores already inside their bodies, ready to infect other trees.

Both partners benefit from this association. The fungus rots and dries the wood, providing a suitable environment and nutrients for growing insect larvae. The wasp, in turn, provides the fungus with a vehicle for invading new hosts.

Although scientifically fascinating, a Sirex–Amylostereum invasion can be ecologically and economically devastating. In 1987, for example, a massive outbreak in the “Green Triangle” in southern Australia caused the death of two million trees valued between A$5 million and A$6 million. Some forests lost up to 80% of their trees.

For more on Sirex, consult B. Slippers, T.A. Coutinho, B.D. Wingfield, and M.J. Wingfield, “A review of the genus Amylostereum and its association with woodwasps”, South African Journal of Science, vol. 99 (2003), pp.70–74.

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The nematodes used in biological control of the Sirex woodwasp.

Photograph: Courtesy of Juanita de Wet

independently of its association with S. noctilio.

So Bernard Slippers and other FABI scientists tried a new way to solve the Sirex invasion riddle. Instead of studying the wasps – as most previous research had done – they examined the fungus, as genetic differences between samples of the fungus collected from different parts of the world provided an excellent way of tracing the spread of the wasps.

Using DNA fingerprinting, the FABI team found that isolates of the fungus from southern hemisphere countries are more closely related to one another than to northern hemisphere isolates. This indicates that the fungus – and, by implication, the wasp as well – were probably introduced from the northern hemisphere into New Zealand, and that it spread from there to Tasmania, Australia, South America, and, most recently, to South Africa.

Accelerated global trade and travel is not the only reason why exotic tree diseases appear more often all over the world. A pest or pathogen that has invaded a new region can go unnoticed for several years as it adapts to its new environment. Once it starts to multiply and spread, however, it can use the newly conquered territory as a springboard for invading other regions, so the global spread of intruders gains momentum with the occupation of each new territory, and this trend is helped along by increased international trade.

The versatile life of a parasitic nematode Nematodes are unsegmented worms with elongated, rounded bodies pointed at both ends.

Most are free-living, but some – such as hookworms and roundworms – spend all or part of their life cycles as parasites. Another example is Deladenus siricidicola – a nematode that spends part of its life cycle as a parasite in the Sirex woodwasp.

Parent nematodes are found in the body cavity of Sirex, where they can grow up to 2 cm in length. As the wasp begins its adult phase, these parent nematodes release into its blood thousands of juvenile nematodes, which then migrate into the wasp’s reproductive system.

A female wasp is sterilized by the parasite, since juvenile nematodes invade all her eggs. She still lays these eggs, but they cannot hatch. The nematodes emerge from the eggs instead, into the vascular tissue of the tree.

The juvenile nematodes in the tree now enter a life cycle completely unlike that of their parasitic parents. They feed on the fungus that the wasp previously deposited into the wood to prepare it for her unborn offspring, and they develop into free-living adult nematodes that seldom become longer than 2 mm. These adults lay eggs, which hatch into juvenile nematodes that again feed on the fungus and grow into the same type of adult. This freeliving cycle might be repeated indefinitely, and nematode populations can reach vast numbers in a tree killed by Sirex and infested with the fungus.

Deladenus siricidicola re-enters its parasitic phase only if an unsterilized woodwasp happens to lay her eggs in a tree already infested with nematodes. The presence of Sirex eggs triggers nearby nematode eggs to develop into a very different form of adult – one that is adapted to penetrate Sirex larvae and grow into the large parasite residing in the body cavity of the adult wasp. Now the nematode can sterilize a new batch of eggs and invade a new tree, thus beginning the free-living cycle anew.

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Responding to the threats The movement of plant pathogens and pests across borders and between continents occurs much more frequently and easily than we had supposed, with potentially devastating consequences.

To combat this trend, we must implement a broad arsenal of disease-management strategies, such as strict quarantine measures against new pests and pathogens. To prevent a pathogen from being confused with similar species or strains that have already been introduced, quarantine measures need to be tailored according to the latest scientific information about its genetic profile. If a pest or pathogen is already present, its impact can be reduced through biological control – a strategy that tries to reinstate the ecological balance that kept it in check in its original environment.

For more about the movement of plant diseases across the globe, read C. Bright’s Life Out of Bounds: Bioinvasion in a borderless world (New York: W. W. Norton, 1998), and M.J. Wingfield, B. Slippers, J. Roux, and B.D. Wingfield, “Worldwide movement of exotic forest fungi, especially in the tropics and the southern hemisphere”, BioScience, vol. 51 (2001), pp.134–140.

Biological control of tree and crop diseases To deal with pests or diseases, biological control uses natural means, such as introduced or naturally occurring predators or parasites, or hormones that inhibit the reproduction of pests.

Biological controls can sometimes substitute for environmentally harmful chemicals, but they pose their own set of risks. Because they use living things as tools, and because living things are complex and unpredictable, there can be undesirable side-effects.

Two examples of biological control of plant diseases that have been examined at FABI are the use of a parasitic nematode, Deladenus siricidicola, to control populations of the Sirex woodwasp (see box), and the use of the bacterium Bacillus subtilis as a biocontrol agent to combat diseases of citrus and avocado fruit.

Nematodes from afar For the last three decades, the nematode D. siricidicola, which sterilizes Sirex woodwasp females during the parasitic phase of its life cycle, has been used extensively for biological control of the wasps in southern hemisphere countries.

Here’s how they do their work. Nematodes are mass-reared on Amylostereum areolatum – the fungus on which they feed during the freeliving part of their life cycle. The nematodes are then injected into a few trees that have been killed by the wasps.

Here they penetrate the Sirex larvae growing in the wood, so that female wasps emerging from these trees after pupation carry the parasitic nematodes with them. When such a female lays her eggs in another tree, the nematodes that have invaded her reproductive

system prevent the eggs from hatching. They also spread throughout the new tree to infect other Sirex larvae that might be growing inside it. From then on, the nematode infection spreads and maintains itself, keeping the Sirex population in check.

This elegant and effective control strategy was developed in Australia, and both South Africa and Brazil have imported and released Australiangrown nematodes as part of their Sirex biocontrol programmes. These imported nematodes initially had limited success establishing a foothold in the new environment, however, and infection rates were much lower than expected. This helps to account for the relentless northward spread of the wasps in South Africa, despite efforts to contain it.

FABI scientists found a possible explanation for these setbacks. They compared the strain of Amylostereum areolatum used to mass rear the nematodes with the strain carried by South African Sirex wasps – and found that they were genetically different. When filaments of the two strains were grown together, they displayed distinct biochemical antagonism. This incompatibility may reduce the nematodes’ ability to propagate in trees or in wasps that carry the South African strain of the fungus. Further research is under way to assess the possible ecological impact of this new strain of the fungus, unintentionally introduced with the nematode.

Avogreen for citrus and avocado The citrus industry is one of the largest in South African agriculture, and is worth about R1.7 billion a year. Avocados, too, are an economically valuable fruit crop cultivated here for local consumption, processing, and export.

Both fruits are vulnerable to disease. Up to 50% of worldwide production of avocados can be wasted as a result of post-harvest diseases, such as Alternaria rot, which is caused by the fungus Alternaria alternata. Alternaria infection causes premature colour change and decayed black or brown spots on fruit surfaces during storage. The common way to combat postharvest diseases is by applying chemical fungicides before harvest. Such chemicals pose risks to the environment and to human health, however, so the search began for natural alternatives.

A strain of the bacterium known as Bacillus subtilis, originally isolated from an avocado orchard in Tzaneen, looked promising. This microorganism naturally inhabits avocado leaf and fruit surfaces, dominating them throughout the year. It causes no harm to the plants or to humans, but crowds out many other organisms that try to invade its ecological niche.

Over 15 years, University of Pretoria researchers cultivated strains of Bacillus subtilis and tested them for effectiveness against several pre- and post-harvest fruit diseases, including Alternaria rot. Concentrates of the bacterium are now produced semi-commercially as the product

Avogreen. Available in liquid and powder form, it is applied to fruit, or to flowers destined to become fruit, and provides safe and effective control of organisms that cause fruit decay.

Carrier bees The challenge was how to apply Avogreen.

Dusting an entire orchard would require vast quantities of bacteria, only a small percentage of which would end up doing what they were meant to do. Applying the biological agent by hand would mean hours of manual labour.

Nature provided the elegant answer. Bees (Apis mellifera) spend much of their lives meticulously visiting flower after flower: they are available in large numbers, and they don’t have to be paid union wages. Persuading bees to carry a biocontrol agent with them on their rounds would be far more efficient than using human beings.

FABI’s Lise Korsten and her colleagues investigated the use of foraging bees to disseminate Avogreen powder. Getting the bees to carry the powder with them on their excursions turned out to be simple. It was placed in pollen inserts – devices installed at beehive entrances that force bees leaving the hive to crawl through a shallow tray.

Determining whether or not the powder actually reached the flowers required creativity and innovation. A solution was to mix Avogreen with fluorescent powder. Armed with portable ultraviolet torches, the researchers conducted evening visits to the orchards and confirmed their success: the bees had indeed done their job and the flowers (the fruit-to-be) were protected against disease. ■

Two electron microscope photographs.

(Top) Bacillus subtilis adhering to the body hair of a bee, and (below) Bacillus subtilis attacking a pathogen.

Photographs: Courtesy of Lise Korsten

Jan Perold is an independent science writer attached part-time to the University of Pretoria.

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Q Careers in S&T There are plenty of job opportunities wherever biotechnology is needed and applied, writes FABI’s science writer, Jan Perold, and biotechnologists work in a great variety of disciplines and fields.

Biotech is needed in Forestry and agriculture • Genetic modification of crop species to improve product quality, disease resistance, and drought tolerance • Testing for the authenticity of cultivars and livestock breeds • Diagnosing and studying the effects of tree, crop, and livestock diseases Medicine and pharmaceutics • Development of safer and more affordable vaccines • Identification of genetic diseases • Genetic counselling • Gene therapy Forensics and anthropology • Solving crimes with the help of genetic evidence • Determining family relationships (for example, in paternity lawsuits) • Study of human population and migration patterns Mining and environment • Biomining (the use of bacteria to leach valuable minerals out of lowgrade or deep ore deposits) • Bioremediation (the use of biological systems to reduce pollution) Who will employ me?

Biotechnology is playing an ever greater economic role. Agricultural companies, for example, must develop genetically modified seed to remain internationally competitive. In the developing world, biotechnology can help to achieve food security for all. Biotechnologists work in a variety of organizations: • Private companies – more than a hundred companies in South Africa use biotechnology in some aspect of their business • Government agencies and parastatals – such as the Agricultural Research Council, the CSIR, and the police service • Academic institutions – such as universities. Some academic institutions have established biotechnology institutes and partnerships that have strong ties with industry.

• Development of biosensors to monitor pollution • Preservation of endangered species through cloning.

Checklist for a biotechnology career To follow a career in biotechnology you’ll need the following personal characteristics: • Perseverance and dedication – it takes several years to Biotechnology is like a tree with many roots and many branches. The qualify as a bio‘roots’ represent the various disciplines, or areas of expertise, that make technologist, and scientific up the field. The ‘branches’ are the various applications of biotechnology. research is demanding analyse vast amounts of data and challenging work. generated by modern biological • Intelligence, curiosity, and flexibility – research biotechnology is a rapidly evolving • Engineering – biosensors (and many field, and it’s important to keep up to other tools used in biotechnology) date with the latest developments. combine biological, electronic and • Teamwork – biotechnology depends mechanical components on the close collaboration between • Law – legal expertise is essential to experts from different disciplines. protect intellectual property rights, A biotechnologist should have tertiary ensure privacy of individual genetic education – preferably in the biological information, and address the ethics of sciences. A B.Sc. and an honours developments such as cloning and degree are essential, although further genetic engineering study to master’s or doctoral level is • Business management – financial, advisable. The following three subjects marketing, and administrative are the most important: acumen are necessary to ensure • Genetics – the branch of biology that success for biotechnology studies heredity and variation in organizations living things • Public relations and social science – • Microbiology – the study of microbecause the field is widely organisms such as bacteria, which are misunderstood, and popular often used in biotechnological acceptance of biotechnology is systems crucial to ensure long-term success, • Biochemistry – the study of chemical it’s important to communicate compounds and processes associated effectively with the public and to with living things. understand the factors that influence Biotechnology also depends on people’s attitudes. ■ expertise in fields outside the biological sciences. An effective way to build a For more information on careers in biotechnology career in biotechnology is to combine a visit these web sites: solid grounding in biology with a www.sabiotechcareers.co.za/ qualification in an area such as the www.pub.ac.za/careers/general.html following: www.biojobnet.com • Computer science – bioinformatics www.massbio.org/directory/companies/ sectors.html focuses on the use of computers to

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South Africa’s Olympic gold medal was won for the men’s 4 100 m freestyle relay (by Roland Schoeman, Lyndon Ferns, Darian Townsend, and Ryk Neethling). The national Paralympic team won 15 gold medals and 10 world records (swimmer Natalie du Toit achieved four world records, and one each came from Fanie Lombaard, Malcolm Pringle, Oscar Pistorius, Tebogo Mokgalagadi, Nicholas Newman, and Zanele Situ).

Photograph: Courtesy of Associated Press

With the Olympic and Paralympic games in Athens came medals to South Africa and the world.

QUEST searched for the science behind the triumphs.

thletics pushes the human body hard, but Olympic triumphs come only to the élite who push their bodies to the limit – even, occasionally, to world records.

Behind such success lies a remarkable combination of physiology, biomechanics, and psychology, which scientists still struggle to understand.

Compared with the merely fit, says Australian sports scientist, John Hawley, an élite athlete is “an entirely different animal.” With their performance-enhancing genes, and helped by the best technology available, athletes still have to work harder than ever before to improve.

Previously unimaginable combinations of extreme physiology and training are now the norm for the top professionals. Roger Bannister, who in 1954 became the first person to run a mile in under four minutes, trained for only 35 minutes a day.

Today, with the record at 3 minutes 43.13 seconds, that seems barely a warm-up.

A

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Science for success For sports scientists and doctors, the Olympics are a laboratory for studying exceptional physical achievement and the pitfalls that get in the way. But their work is not easy.

Biological data are difficult to get from top athletes, who seldom agree to interrupt their training programmes to become involved in experiments or to donate blood or muscle samples.

Furthermore, coaches – mostly former athletes – keep to training methods they know rather than trying out new ideas. So sports scientists tend to use information from recreational athletes, rather than from top professionals, to examine in a lab the results of training techniques used in the field. Such studies are often inconclusive.

Advanced technologies that give definitive and immediate feedback, though, are popular among the world’s trainers, and tracking performance in real time through videos has had a major impact on technique training in events such as high-jump and diving.

South Africa’s own CSIR Sports Technology Centre (STC) has done some pioneering work in developing and using video footage and specialized software in what is called notional or performance analysis, used by coaches to measure performance objectively and to help athletes to focus their training for improvement.

Digital cameras record and monitor an athlete’s work from different angles; then the information is analysed to create benchmarks, for instance, and to watch technical progress. “One is able to review an athlete’s performance instantaneously. In some interventions, there is no need to take the footage back to a lab,” explains STC manager, Tony Kirkbride, whose centre works with the National Olympic Committee of South Africa and Disability Sport South Africa, as well as with other national sporting bodies.

“There is a very strong correlation between an athlete’s performance and the amount of technology intervention he/she has had in training,” Kirkbride

adds. “Those athletes who rely solely on raw talent for medals are competing against athletes who use every possible legal technique to enhance performance.”

Another technology that has become popular among coaches is electromyography (EMG), which measures electrical activity in working muscles. A trainer who brought a gymnast to the US Olympic Training Center in Colorado Springs for EMG analysis was amazed to find that the muscle groups he had been focusing on for the ‘Maltese cross’ – a position on the rings in which a gymnast holds the body up in mid-air in a horizontal position – were not the ones that the gymnast was actually using for the move.

The role of genes Top athletes have genes that enable extraordinary athletic performance.

The exceptional stamina of Eero Mäntyranta, the 1964 Finnish crosscountry skiing gold medallist, for example, may be due to a mutation in the gene encoding for erythropoietin (a protein that regulates the production of red blood cells). Hundreds of genes can play their part – from those determining body proportions to those that help muscles to utilize oxygen and nutrients.

Genetic responses to environmental triggers may also affect training.

Research into high-altitude training, for instance (thought to improve performance) shows that not everyone necessarily benefits. Some athletes show increased levels of the oxygencarrying protein haemoglobin found in red blood cells, whereas others show no change. For greater certainty, scientists would need to examine all the genes activated by low oxygen levels in a big enough pool of athletes, but such research is not yet possible.

Highs and lows Athletic schedules are punishing, and training can bring peak performance – or the very opposite. Pushing too hard, for instance, can cause unexplained underperformance syndrome (UPS), also known as ‘over-training syndrome’. One in ten athletes is thought to experience this condition.

They normally recover after a period of rest, but it can ruin preparation for major events.

Rowers, for instance, typically train twice a day, five or six days a week, and push their bodies beyond their

normal limits for an intense week or two before a competition. Such ‘overreaching’ exhausts them in the short term, but in the long term it can force their bodies to adapt to intense exertion, which improves race performance. Those who don’t immediately recover, however, stay exhausted and may become unable to compete.

Factors in the hormone and immune systems seem to be linked with UPS, and sports scientists are offering tentative theories. Lucille Lakier Smith, at Pretoria’s Tshwane University of Technology, has postulated that when athletes over-reach they may damage muscle, which prompts an immune response. She has measured levels of certain anti-inflammatory cytokines (molecules used to exchange signals between cells) that increase with extreme immune reactions to infection.

But UPS, in the form of fatigue and aching joints, can also occur when there is no infection. British exercise physiologist, Paula Ansley-Robson (who herself suffered from UPS), has studied a particular cytokine, interleukin-6 (IL-6), whose levels often rise when someone has a cold or flu. It makes the body tired and helps to slow it down while it fights an infection. IL-6 is also involved in regulating glucose energy stores during exercise. Levels can rise 100-fold during a marathon and are partly responsible for feelings of tiredness during a race. Some people – such as chronic fatigue sufferers – are more sensitive to the cytokine than others, and after injections of IL-6 they become more tired more quickly, and for longer, than control subjects. The research continues.

Environmental hazards For a top cyclist or runner, city air pollution can be a problem. Athens is badly polluted and Beijing (the venue for the next Olympics) can be even worse.

Two pollutants arouse particular concern: ozone and particulates (tiny bits of soot and other matter). Both can irritate the lungs and cause asthmatic symptoms. Athens in August has brownish–yellow smog of photochemical pollutants; when it hangs, ozone levels can rise to levels more than 25% higher than the World Health Organization’s recommended limit.

It is unclear how particulates irritate the lungs, but it seems that coatings of tiny amounts of metals such as iron

or copper on flecks of dust and soot can trigger reactions in the lungs that generate highly reactive free radicals.

This can lead to inflammation of lung tissue, tightening of the chest, and shortage of breath. If fluid enters the lung, emergency treatment is needed.

Heavy exercise can make the problem worse. In conditions where pollution can cause asthma-like symptoms in about 13% of normal people, the proportion rises to 20% among athletes and up to 50% among cyclists, who breathe heavily during their events. Most at risk are endurance and outdoor athletes, rather than table-tennis players, for instance.

Of the two airborne irritants, ozone is thought to cause most problems.

Athletes can cycle some 150 litres of air in and out of their lungs every minute during competition – ten times more than normal – which exposes them to more pollution. They also inhale much more deeply, which takes pollutants into the deepest regions of the lungs. ■ For sources see Nature, 5 August 2004 and visit http://sport.iafrica.com/news and www.csir.co.za For more on sports science visit http://web.uct.ac.za/depts/essm For more on the Athens games visit www.nocsa.co.za, www.dissa.co.za, and http://web.uct.ac.za/depts/essm

Watchpoints for athletes For athletic success you need the right diet, physical training, and mental preparation, with technology intervention to give competitive advantage. You also need to protect yourself against pitfalls.

UPS Symptoms of underperformance syndrome (UPS) include constant minor infections, such as colds, that won’t go away; aching joints; fatigue; sleep and mood disturbances; loss of appetite; slow healing of wounds; and gastrointestinal disturbances. If two weeks’ relative rest doesn’t restore performance, you could have UPS. Protect yourself ■ Rest for at least six hours between training sessions (IL-6 levels are significantly higher among subjects who rest for only three hours) ■ Monitor your mood – psychological stress is thought to contribute to UPS, though nobody knows why ■ When you notice the symptoms, stop training and rest.

Air pollution ■ Know if you are prone to exercise-induced asthma in polluted air ■ Restrict training when ozone levels are high ■ Take anti-inflammatory medication or, if you are likely to be tested for performance-enhancing drug use, take antioxidizing agents such as vitamins C and E, which help to protect against the inflammatory effects of air pollution by mopping up noxious free radicals before they can do harm.

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An octahedral diamond (measuring 7 mm across) in kimberlite matrix, from De Beers Mine in Kimberley.

Photograph: Denis Finin. Photo courtesy of the American Museum of Natural History

They’re precious, they’re beautiful, but are they as old as we thought they were?

Geophysicist Alan Rice examines the evidence.

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Are diamonds truly ‘forever’?

Not if you hit them with a hammer.

Although diamonds are the hardest known substance on earth, they are brittle. And, like the tree that snapped in the gale because it couldn’t bend, they are vulnerable. Every diamond cutter awaits with dread the possibility the diamond will shatter rather than cleave when the hammer is brought down on the chisel.

Diamonds are pure carbon, which makes them combustible as well. They can burn. Diamond is one of the several ‘allotropic’* forms of the element carbon, as are graphite, fullerenes, coal, charcoal.... And, like charcoal, diamonds could fuel a braai – an expensive one.

Diamonds found in nature are considered to be in a ‘metastable’ state, which implies that the substance of interest would prefer to be in another state than the one it’s in at present. Theoretically, all physical systems in a metastable state will eventually run down into a stable one, at which point there’s no drive for further change. But it would take a very long time for a diamond to become a more ‘stable’ form of carbon (i.e. to turn into graphite) in the conditions found at the Earth’s surface.

It would, for instance, take many times the present age of the Earth – barring accidental blows and fire! A definition of ‘forever’ in this case might then be ‘many times the age of the Earth’.

How and why we make diamonds

and heating, and that it can occur in less extreme conditions. Chemical Vapour Deposition (CVD) diamonds are formed at temperatures as low as room temperature and pressures of 1/1000 of an atmosphere (that is, in a decent vacuum). Often carbon monoxide is employed in these lowtemperature, low-pressure processes (as well as in high-temperature and high-pressure ones).

Extensive ongoing research is being directed at understanding diamond formation. Under the right conditions, they can form in microseconds. The motivation that propels this research relates more to the industrial applications of diamonds than to their cosmetic value as jewellery, as diamonds have important uses other than the romantic ones.

‘pipes’ – some of them containing diamonds – eventually taper into a volcanic feeder vein that provides a conduit, from the depths at which it was thought diamonds were formed, to the surface of the Earth. Kimberlite pipes may be up to several kilometres deep and half a kilometre across at the surface. The kimberlitic magma (or molten rock) out of which the pipes were formed has been thought to carry ancient, previously formed diamonds with it as it rises to the surface through the feeder veins.

Associating diamonds with kimberlite pipes defined future exploration strategies: look for kimberlites! Not just any kimberlite would do. Of thousands of kimberlite pipes, only a few carried diamonds and only a few of those contained enough diamonds to make them worth mining. Those pipes initially found to be commercially viable were located in regions of the Earth that had seen little distortion (folding, shifting) over time, and these very old areas, called ‘cratons’, were located on portions of the continents that extended deeper into the Earth’s mantle than elsewhere. But questions arise as to the very ancient age of diamonds when we discover that they’re also found in places far from cratons, and from the old crust of continents – in Hawaii, for instance, which is a very young island in the middle of the Pacific Ocean.

How they reached the Earth’s surface

The age debate

Diamonds can also be manufactured.

Such diamonds are called synthetic or ‘cultured’ (the term ‘cultured’ has come from the cultivated pearl industries).

The first successful diamond syntheses occurred in the mid-1900s.

These early efforts required heating and compressing graphite to high temperatures and very high pressures: over 1 000 C and over 50 000 atmospheres. Such requirements seemed to support the view that ‘natural’ diamonds, found on the Earth, had to have been formed as deep or deeper than 150 km beneath the surface of the Earth. Only at these depths were temperatures and pressures available to replicate the conditions in which early laboratory diamonds were created.

Further work established that diamond formation is a far more complex process than just squeezing * Allotropy means the existence of more than one physical form of an element. The difference may be in bonding (e.g. graphite

▲ ▲

If, indeed, high pressure and high temperatures were needed to form diamonds in nature, and if we want to know where to mine them, we need to understand how natural diamonds get to the surface of the Earth from depths we once thought necessary for their formation.

Until the mid-19th century, diamonds were found seemingly helter-skelter across the globe, lending no clue as to the mechanism responsible for their appearance and distribution. The discovery of the famous diamond mines at Kimberley in South Africa’s Northern Cape province gave the first indication that some common factor might be associated with the occurrence of natural diamonds.

Kimberley diamonds come from a bluish friable rock of volcanic origin, appropriately named ‘kimberlite’. The rock itself is of the nature of a volcanic plug or ‘pipe’, extending from the surface of the Earth downward in the shape of a carrot. These kimberlite

The technological breakthrough of radiometric dating, some decades ago, strengthened the supposition that natural diamonds might be very old. A diamond itself cannot be dated, as any carbon of which the diamonds are composed would have long ago ceased to be radioactive. But natural diamonds almost always contain some minute Industrial uses of diamonds They are ■ vital in providing abrasives to assist in drilling

and cutting ■ potentially applicable in the semiconductor industries ■ electrical insulators – and they can be ‘doped’ (injected with atoms of other elements) to add particular electrical properties that help them function as transistors ■ a potential circuit element, as they have the highest thermal conductivity of any known material.

(The more quickly information is pushed in and out of a mother board on a computer, the more quickly it heats up. Such heating limits the speed at which the computer can operate. Using diamond as a circuit substrate would allow computers to run as much as 10 times faster than they do now.)

and diamond; ozone and dioxygen), or in crystal form (e.g. in most metallic elements). The various forms are called ‘allotropes’.

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Fact file Q ▲

contaminant and this material can often be dated, yielding ages running to 3.5 billion years: nearly as old as the Earth whose age, we believe, is about 4.5 billion years. This observation neatly fitted the view that kimberlite magmas arose in and passed through ancient portions of the Earth.

Certainly, contaminants within a diamond may be old, but is the diamond itself as old as its contaminants? Could the diamond be something like this year’s winter ice surrounding a more ancient pebble?

Logic says that diamonds must be at least as old as the kimberlite pipes in which they’ve been found, and the ages of the pipes range from several billions of years old to only 65 million years old. But recent technical advances call into question the supposition that diamonds are older than the kimberlite pipes in which they appear.

Diamonds can be ‘annealed’ to rid them of flaws and contamination. That is, an ugly diamond (yes, there are ugly diamonds!) can be placed into a hightech pressure cooker, brought to high temperature and pressure for tens of minutes, and come out ... perfect. These ‘born again’ diamonds are known in the jewellery trade as HPHT (high pressure high temperature) diamonds. The

environment at the depths in which we thought the diamonds had formed and resided for billions of years is similar to that of the pressure cooker. If diamonds more ancient than the pipes came up with the kimberlite magmas, shouldn’t they be perfect too? The fact that they are not leaves this possibility: they were formed when the pipe exploded into its place rather than earlier, and, as they formed, took up ancient contaminants carried by the magma.

One likely scenario for kimberlite emplacement is that: the kimberlite magma moves upward from deep down, gathers in large volumes several kilometres beneath the Earth’s surface, and finally explodes there, blasting pipes through to the surface. The experiences of explosive excavation engineering (including the results of underground nuclear bomb testing) strengthen this conjecture. They also indicate that the temperatures and pressures involved to make the pipes are great enough to make diamonds (remember, the explosion must be strong enough to generate a pipe up to several kilometres deep and half a kilometre across at the surface). A mechanism by which this could be done is similar to one employed in industry to make diamonds: 2CO ➔ C(diamond) + CO2. That is, two parts of carbon monoxide will yield one part diamond and one part carbon dioxide. These processes would not require diamonds to be any more ancient than the pipe’s formation date.

Forever – into the future

For details see Alan Rice, “Do diamond-inclusion ages date only the protolith, not the diamond formation?” South African Journal of Science, vol. 99 (2003), pp.227–233. For more on HPHT diamonds read A. Cockburn, “Diamonds: the real story”, National Geographic, vol. 201 (2002), no. 3, pp.2–35. For Quest’s Fact File source material see G. Smith, “The allure, magic and mystery – a brief history of diamonds”, SAIMM: Journal of the South African Institute of Mining and Metallurgy, vol. 103 (2003), pp.529–534, and read other articles on diamonds in this special issue. For information about famous diamonds, visit www.minelinks.com/alluvial/diamonds_1.html and for more about De Beers, visit www.debeersgroup.com

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Brand new sizeable man-made diamonds – greater than 3 carats and flawless – are now being manufactured.

They will last several lifetimes of the Earth ... if they’re not hammered or used to fuel a braai. They are not antique, though, so hardly ‘forever’ in the backward time direction. You can now buy a relatively inexpensive modern diamond, or you can pay maybe ten thousand times more for an antique natural diamond that could be 65 million or perhaps billions of years old.

There will probably be a market for antique diamonds – for at least as long as diamonds remain a girl’s best friend.

But the more we learn about either of these friends, it seems, the less we really understand them. ■ Dr Alan Rice worked in South Africa for many years. He is now based in the USA at the Department of Earth and Planetary Sciences, American Museum of Natural History, 79th St and Central Park West, New York, NY 10024-5192.

Definition Diamond n.

Derived from the Greek (‘adamas’) meaning ‘unconquerable, unalterable, inflexible’ An allotropic form of pure carbon that has crystallized in the cubic system; a diamond can take up impurities during crystallization that affect its physical properties; it is the hardest known mineral (with a hardness of 10 on the Mohs scale) Has a relative density of approximately 3.52 and a refractive index of 2.42 Can be white (colourless), yellow, brown, green, orange, blue, pink, grey, black, or red, depending on its structural defects or the impurities it contains Has great brilliance and value as a gemstone (in its transparent varieties) Has extensive industrial uses.

Found in nature In two primary rock types: kimberlites and lamproites (generically termed ‘kimberlites’: both rich in magnesium, highly potassic, alkaline igneous rocks) In alluvial deposits (e.g. diamonds eroded from kimberlites have been transported by rivers and then deposited).

The diamond industry It started when diamonds were first mined in India over 3 000 years ago; the modern industry began when diamonds were discovered in South Africa in the late 1800s.

About 25 countries mine diamonds, chief among them being Botswana, Russia, Angola, South Africa, Canada, Namibia, and Australia (which, together, supplied about 85% of the world’s rough diamonds in 2002).

The world’s leading diamond cutting centres are in Antwerp, Tel Aviv, Mumbai, and New York.

Of the 115 million carats of gem and industrial diamonds recovered, about half are classified as gem or near-gem quality. The 2002 value of the rough gem trade was US$8 billion.

Value past and present Till the 15th century, only kings wore diamonds – as symbols of strength, courage, and invincibility. The discovery of large, famous stones in India (e.g. the Koh-i-Noor) increased the popularity and value of diamonds during the Middle Ages.

Portrayed through history as magical objects, diamonds were thought to cure illness and heal wounds, ward off devils and nightmares, and bring a wearer

Q News good luck, protection from harm, and the ability to charm and attract others; Cupid’s arrows were said to be tipped with magical diamonds; the ancient Greeks believed that the ‘fire’ of a diamond reflected the flame of constant love.

The first diamond engagement ring was given in 1477 to Mary of Burgundy by the Archduke Maximilian of Austria; placing a ring on the third finger of the left hand comes from the early Egyptian belief that the vein of love runs from the heart to the tip of the third finger.

Initially, rough diamonds were used as talismans or jewellery. The polishing of diamonds was first recorded in India and probably began in the 14th century; the first reference to diamond cutting comes from Antwerp in 1550.

Mine owners used to tell mineworkers that diamonds were poisonous, to prevent them from swallowing stones in order to smuggle them out of mines.

Some famous South African diamonds The Star of Africa, the world’s biggest cut diamond (weighing 530.20 carats), is set in the royal sceptre and kept with the crown jewels in England’s Tower of London. Pear-shaped, with 74 facets, it was the largest of more than a hundred diamonds cut from the largest diamond crystal ever found: the 3 106 carat Cullinan, recovered at the De Beers Premier Mine (in 2003 renamed the Cullinan Diamond Mine) in South Africa in 1905.

The Excelsior, at 995.2 carats, is probably the second largest stone ever found. In 1893, a South African mineworker extracted it from a spadeful of gravel and delivered it to the mine manager: his reward was £500 and a horse with saddle and bridle. The stone was named Excelsior, meaning ‘higher’, because its original shape was flat on one side, rising to a peak on the other. It was cut into 21 diamonds, of which the largest weighed 69.8 carats.

The Taylor-Burton diamond: this pearshaped, 69.42-carat diamond was cut from a rough stone, weighing 240.8 carats, recovered in 1966 at the Premier Mine. Purchased on auction by Cartier Inc. for a record price of US$1 050 000, it was then bought by Richard Burton for Elizabeth Taylor. When it was displayed at Cartier’s, crowds of up to 6 000 people came to view it each day. It was sold in 1978 for US$5 million.

The Centenary Diamond, discovered at the Premier Mine in 1986, weighed 599.1 carats in the rough. Three years were needed to transform it into the world’s largest modern-cut, top-colour, flawless 273.85-carat diamond with 247 facets. ■

Outer space Saturn’s secrets When the Cassini spacecraft entered Saturn’s orbit on 1 July, it immediately began sending pictures with surprising revelations about the planet, its rings, and its moons. On first seeing these closest ever images of Saturn’s distinctive disk of rings, Carolyn Porco, leader of Cassini’s imaging team, said, “I thought [they were] playing tricks on me and showing me a simulation of the rings and not the rings themselves.”

Cassini’s cameras revealed the expected waves and ripples in the rings Artist’s rendition of the Cassini spacecraft approaching Saturn. caused by the gravity of Saturn’s moons.

Photograph: Courtesy NASA/JPL-Caltech They also found a new, relatively small radiation belt of high-energy particles, Saturn. The spacecraft’s radio and plasma extending around Saturn from about wave instrument has picked up the sounds of 24 000 km above the top of the planet’s clouds the Saturnian electric storm, described by to the inner edge of its innermost rings. physicist Bill Kurth (who has been analysing Scientists have never before seen a single the data) as a “crackle and pop” similar to the radiation belt isolated from a planet’s main noise one hears “on an AM radio broadcast radiation belts, which lie at far greater during a thunderstorm”. The storms seem distances. Says Cassini mission scientist different in timing and duration from those Donald Mitchell (at Johns Hopkins University), observed by the two Voyager spacecraft over “we did not expect ... that radiation belt 20 years ago and more sporadic – perhaps, particles can hop over obstructions like scientists speculate, because the rings are Saturn’s rings.” casting deep shadows over different parts of Most of the rings are 99% pure water ice, the planet than two decades earlier. but Cassini’s images show the ‘dirt’ they Cassini has travelled within 340 000 km of contain, comprising a mixture of mineral grains Saturn’s largest moon, Titan, and observed a and organic molecules. A 300-km-wide streak glow of methane there, revealing that its of such dirt, near the outer edge of the rings, atmosphere extends more than 700 km above is made by the tiny moon Pan, whose the surface. In January 2005, a small diameter is just 20 km. As it circles Saturn, it spacecraft launched from Cassini will be the clears a path through the ice, leaving the first to penetrate this atmosphere to mineral trail in its wake. investigate Titan directly.

The mission’s scientists also report curious Reported in New Scientist, 10 July 2004, Nature, 15 July 2004, and the New York Times, 6 August 2004. lightning patterns and thunderstorms on

Messenger off to Mercury

Death throes of stars

The Messenger spacecraft blasted off on its seven-year, 8-billion-km journey to Mercury on 3 August as part of NASA’s Discovery programme. Once it starts orbiting the planet, its seven instruments will study Mercury’s heavily cratered surface, the composition of its core, its magnetic field, and its thin atmosphere.

The Mariner 10 probe, sent to Mercury in the mid-1970s, mapped half the planet’s surface; the other half remains a mystery.

What is known about Mercury is that twothirds of it is made of iron; the temperature reaches 420 C at its equator and 130 in the shadow of craters at its poles.

The mission’s price tag is US$427 million – this relatively low cost was made possible by a compromise between the weight of Messenger (half of which is fuel) and the inexpensive rocket used to launch it.

At the end of its life, a star begins to pulsate – nuclear reactions ignite; their energy lifts the surface of the star and cools its interior, which allows the star to shrink again; then the cycle restarts.

This phenomenon was known in low-mass stars, such as our Sun. In 2000, using a computer model, Ernst Dorfi and Alfred Gautschy of the University of Vienna in Austria predicted that more massive stars should also pulsate before they die. There were doubts about this hypothesis but now there is new evidence consistent with their theory. Daren DePoy and colleagues from Ohio State University in Columbus have found a giant pulsating star near the centre of our galaxy. Its cycle of pulsation takes 9.725 days and its brightness alters by a factor of about 1.5. This star is 90 times the diameter of our Sun and between 10 and 50 times its mass.

Reported in the New York Times, 3 August 2004.

Reported in New Scientist, 2 October 2004.

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The trade in traditional medicines forms part of a multimillion-rand ‘hidden economy’ in southern Africa. Tony Dold and Michelle Cocks examine this complex resource management issue facing conservation agencies, health care professionals, and resource users in South Africa.

Traditional medicine Troubles come in many forms – physical, mental, spiritual, and cultural – and traditional medicines are used to treat them all. The supply of ingredients needs to be secured, however. If South Africa’s medicinal plants are to carry on offering protection from sorcery and evil spirits and ensuring good health and fortune, they need to be protected.

Customers About 80% (27 million) of the African population in South Africa make use of traditional medicines. With a medical doctor to total population ratio in South Africa of 1:17 400 reported in 1993, there is no doubt that traditional medicine plays an important role in the health care system in the country.

Rural, low-income groups of people are not the only ones to use traditional medicine – a variety of people see it as essential for treating certain conditions, irrespective of their education and income levels.

Traders The key medicinal plant traders are informal gathererhawkers, traditional healers (over 100 000 practising in the country), and owners of muthi and amayeza esiXhosa stores.

Using and trading plants for medicine is no longer confined to traditional healers, but has entered both the informal and formal entrepreneurial sectors of South Africa’s economy, so the number of herbal gatherers and traders has increased.

The traders are mainly black middle-aged (62%) women (75%), with low Informal medicinal plant market in King William’s Town. levels of education (50%

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below grade 8), earning less than R500 per month (62%).

The medicinal plant industry, therefore, plays a critical role in empowering a large number of women. Lack of access to such opportunities would leave them and their families destitute.

Most often, traders harvest plant material themselves, with the help of family members or friends, and they are the first and largest link in the market chain. The marketing of medicinal plants is largely informal.

Plants traded Most of the 166 plant species harvested for trade in the Eastern Cape province come from three biomes, i.e. grassland (34%), valley thicket (23%), forest (18%), and 13% from both forest and thicket. Some species (12%) are also harvested from the fynbos biome in the west of the province, wetlands, and disturbed areas. Forest is significantly more threatened than grassland and thicket because the largest mass (7.2 kg/km2) of medicinal plants is harvested from there.

Market value The medicinal trade in indigenous plants is worth about R270 million each year in South Africa. Almost 525 tonnes of plant material, valued at about R27 million per annum, is traded in six urban centres in the Eastern Cape alone.

Most of the material is sold in its natural, unprocessed form, in small quantities ranging in price from R1 to R20, the average being R5 for a single item.

Conservation status Intensive harvesting of more than 700 wild plant species for medicinal purposes poses a serious threat to biodiversity.

The shift to a cash economy and the emergence of commercial harvesters – into what was previously a specialist activity restricted to traditional healers – mean that medicinal plants have become a common property resource, and there are few incentives for resource management or traditional conservation practices.

Traditional harvesting areas are coming under pressure, and there is a growing shortage of popular medicinal plants, which leads to price increases. As a result, several plant

species have been exploited so greatly that they are seldom found in unprotected areas.

Of the 60 most frequently traded plant species, 63% are bulbs, tubers, and roots that are removed entirely from the ground and the vegetative parts discarded; 17% are woody species whose bark is removed, which kills the plant; 13% are whole plants; and 7% are vegetative parts only. All plants are harvested from wild sources only and no attempts have been made to cultivate medicinal plants in the Eastern Cape.

Some 93% of the species traded are harvested unsustainably as they are entirely or partially removed, resulting in the death of the plants.

Wild plant stocks are being depleted to dangerously low levels, with 34 medicinal plant species earmarked for conservation management. Because of their over-exploitation for medicinal purposes, three species are listed as World Conservation Union (International Union for Conservation of Nature and Natural Resources – IUCN) Red Data species: Bowiea volubilis (Vulnerable), Cassipourea flanaganii (Critically Endangered), and Ocotea bullata (Vulnerable).

What about the future?

Many traditional healers report that the number of their patients has increased over the past five years, and they are expected to grow further, mainly because of HIV/AIDS. So the current demand for medicinal plants is likely to grow.

Replacing traditional medicines with modern scientific medicines is both impractical and inappropriate; it is therefore crucial to take steps to accommodate the medicinal plant trade in South Africa.

As formal and traditional conservation measures have been largely unsuccessful, we need urgently to develop new methods of cultivation as well as management programmes to conserve biodiversity, protect threatened species, and still ensure that those who rely on the trade of medicinal plants for health care and for their livelihoods have access to the plants.

Cultivation is the answer Domesticating and cultivating indigenous medicinal plants can decrease pressure on wild populations and provide the means to earn a living. Indeed, the high prices obtained for some medicinal plant species make them potential new crops for small-scale farmers and village home gardens.

Although some traditional healing practices require plants to be harvested from the wild, most urban-based healers, patients, and customers in the Eastern Cape report that they would readily use cultivated plants for medicinal purposes if these became available.

A recent survey of 194 homes in three villages in the King William’s Town district assessed the potential for domesticating medicinal plant species in home gardens.

Several trends emerged: • More than half of the homes in the study site have more than one medicinal plant (including more than 50 different species) already growing in their gardens for domestic use. Many of these, such as bulbous and succulent plants, are easily Bark removed from a tree for transplanted. They are grown on a very medicinal purposes. small scale and little or no active effort is Photographs: Courtesy of Tony Dold made to propagate them.

• Medicinal plants are grown separately from garden food crops and from areas of high traffic in the garden to reduce the chance of physical damage and metaphysical contamination. Containers are seldom used.

• Some species are not cultivated because it is considered taboo to do so and because seeds and seedlings are not easy to obtain. Communal or ‘community’ nurseries were not seen as appropriate for growing medicinal plants, nor was the application of chemical fertilizers.

Home gardens could solve the problem of over-exploitation.

They are ideally suited for the domestication of medicinal plants, both for subsistence and for generating income. At the same time, they help to reduce harvesting pressure on wild plant populations and to conserve biodiversity. ■ Tony Dold is at the Selmar Schonland Herbarium and Michelle Cocks is at the Institute for Social and Economic Research, both at Rhodes University.

For details, read A.P. Dold and M.L. Cocks, “The trade in medicinal plants in the Eastern Cape Province, South Africa”, South African Journal of Science, vol. 99 (2003), no. 9/10, pp.589–597. For more on South African medicinal plants, consult B.-E. van Wyk, B. van Oudtshoorn, and N. Gericke, Medicinal Plants of South Africa (Pretoria: Briza, 1997). Visit www.ru.ac.za/institutes/iser/ (click on Research).

The top ten most frequently sold plants in the Eastern Cape Plant name

Xhosa name

Common name

Medicinal use

Average price per kg (R)

Annual turnover (kg) (Market value)

Hypoxis hemerocallidea

Ilabatheka

African potato

Tuber used to treat kidney/bladder disorders

30

11 000

(R322 500)

Ilex mitis

Isidumo

Cape holly

The bark is used as an emetic

41

5 300

(R210 500)

Rhoicissus digitata

Uchithibhunga

Wild grape

Tuber used as a body wash to treat cultural afflictions*, headaches, and high blood pressure

11

6 500

(R75 200)

Rubia petiolaris

Impendulo

Vaskloubossie

The leaves are used as an emetic to treat skin disorders

68

2 100

(R89 500)

Helichrysum odoratissimum

Impepho

Everlasting

The leaves are used in healing rituals

27

2 200

(R149 500)

Curtisia dentata

Umlahleni

Assegaai

The bark is used to treat cultural afflictions

60

2 300

(R170 600)

Protorhus longifolia

Izintlwa

Red beech

The bark is used to treat cultural afflictions

30

2 700

(R72 600)

Bulbine latifolia

Uyakayakana

Wildekopieva

The bulb used to treat bladder infection, and as a veterinary medicine

31

3 200

(R98 600)

Gasteria bicolor

iNtelezi

Gasteria

Plant used as a body wash to treat cultural afflictions

50

3 400

(R226 800)

Rapanea melanophloeos

Umaphipha

Cape beech

The bark is used as an emetic to treat cultural afflictions

38

2 000

(R92 000)

* affliction n. physical or mental distress, especially pain or illness

Quest 1(2) 2 0 0 4 17

Q The S&T tourist

T h e J o h a n n e s b u rg Z o o The Johannesburg Zoo celebrates its centenary in 2004. Like other zoos around the country, it’s a great place to visit at any time of year. he Johannesburg Zoo has come a long way in a hundred years.

In 1904 it was home to a lion, a baboon, a leopard, two monkeys, two sable antelope, a golden eagle, a genet, two porcupines, and a giraffe. Today it has 2 000 animals and 380 species.

Hermann Eckstein’s involvement in developing the new mining town of Johannesburg included having three million trees planted in the area we call Saxonwold. After he had died, his firm, H. Eckstein & Co., gave the people of Johannesburg 200 acres of land in 1904 as a place of recreation in perpetuity. At the suggestion of Sir Percy FitzPatrick, a partner in the firm, the land now comprising Zoo Lake and the Johannesburg Zoo was called the Hermann Eckstein Park.

By 1910, the Zoo was one of Johannesburg’s favourite places for a day’s outing, with children’s playgrounds, gardens, a bandstand, and a tramway that stopped at the zoo gates. A stone elephant and rhino house was built in 1913, followed by a hippo house and pool a few years later. In 1937 the Zoo bought an Asian elephant and a Bactrian camel, which were trained for rides. Donkey and pony cart rides started in the late 1920s and, with llama and zebra rides, were a great attraction until the 1960s.

Some of the old stone buildings of the 1920s and 1930s are still used, though not as animal houses. The elephant house was converted into an auditorium in the 1980s and is hired out for conferences and functions.

Johannesburg Zoo was one of the earliest zoos to adopt the principle of ‘cages without bars’ in as early as 1921. Instead it used a moated camp system with vegetation and artificial rocks to give a natural look. The lion enclosure (sponsored by AngloGold and opened in 2000) followed this tradition, and was the first of its kind in the world, using islands and moats to separate the groups of animals.

The new ape house, opened on 24 September 2004 by Mayor Amos Masondo, offers another open habitat.

The Zoo houses all the great apes –

T

gorilla, chimpanzee, and orang-utan.

Their new home has increased from 75 m2 to 2 000 m2 and has trees, natural vegetation, streams, and a stimulating environment that includes an artificial termite heap in which the animals use sticks to ‘fish’ for food like honey or jam. The enlarged ape house also helps in the rescue and rehabilitation of chimpanzees that have been abused – during laboratory experiments, in circuses, or in the pet trade, for example. Once such chimps are brought back to health, they go to one of several chimp sanctuaries in Africa. There they are introduced to other chimps and socialized into family groups. Most rehabilitated chimps are kept in sanctuaries rather than reintroduced into the wild, as much of their home territory is in a state of war.

Besides recreation and conservation, the Zoo concerns itself with research and education. It also provides information about animal diseases and gives medical care to animals in its fully equipped hospital. The Biofacts Museum has a large collection of preserved animal material such as skulls, skins, eggs, and feathers. These can be hired or in some cases, such as feathers, bought. ■

Dominant male chimpanzee enjoying his new natural environment.

Female chimpanzee checks out the new ape house.

Tours & programmes The Zoo brings environmental subjects to life for everyone – families, schoolgoers, clubs and interest groups, and senior citizens. Phone (011) 646 2000 for information and bookings.

■ Zoo School – wildlife and conservation lessons for grades 1–12: weekdays all year (tel. Deona, ext. 263 for the topics) ■ Behind-the-scenes tours – go where zookeepers go and see close up how the animals are fed and cared for medically (tel. Deona, ext. 263) ■ Zoo-to-you – the Zoo will visit you and your school with slithery animals and cute fluffy animals (tel. Lawrence Tshokgohle, ext. 259) ■ Honey Badger Club – 7–13-year-olds meet monthly for demonstrations and interaction with animals (tel. Martin-John van Rooyen, ext. 262) ■ Sunset tours – see diurnal and nocturnal beasts ‘change shifts’ (bring a picnic) ■ Zoo ferry tours – a guided tour on a private tractor-drawn ferry ■ Moonlight tours – enjoy night creatures by torchlight, then refreshments around a blazing bonfire ■ Senior citizens’ tours – meet the animals close up from your tractor-drawn ferry ■ Be MAD – 14–19-year-olds enjoy a day each month making the lives of animals more fun and stimulating (tel. Louise Gordon, ext. 254) ■ Sleep-overs – camp overnight among the animals ■ Holiday programmes – use school holidays to learn about the world of wildlife (tel. Martin-John, ext. 262) ■ Edutainment – visit the new education centre filled with skulls, bones, skins, and stuffed animals; consult the reference library; try the virtual touch-screen.

For general information phone (011) 646 2000, (011) 486 0244, or visit www.jhbzoo.org.za

Quest 1(2) 2 0 0 4 19

Computing Q

Be obvious – e.g. search for Einstein rather than scientists.

Look for synonyms – by typing in the ~ symbol (top left of your keyboard).

E.g. to find technical help with PowerPoint, type ~help PowerPoint and you’ll get PowerPoint help as well as tips, hints, advice, guide, support, instructions, tutorials, and FAQs. Search within results – if you get too many results, click on the “Search within results” link at the bottom of any results page, and then add another keyword.

Find a whole phrase – or words in a particular order, by enclosing them in double quotation marks, e.g. “red red rose”.

Tell Google what you don’t want – use a minus sign or hyphen (-) before the words you don’t want, e.g. tanks -“think tanks”.

Let Google guess for you – use an asterisk (*) in place of a whole word, e.g. “the * is mightier than the sword”.

Get the right address – the Web address (or URL) of each page is shown in the results. If you click on the underlined blue link (title) and you get the message “page cannot be displayed”, try the green line that gives the site’s address.

Go to the home page – let’s say Google took you to http://www-gap.dcs.st-and. ac.uk/~history/Mathematicians/Einstein. html and you want to go to the site’s home page to see what else it offers or what it is, go to your browser’s address box and cut, from the end, the sections after each slash (/), e.g. leaving you with http://www-gap.dcs.st-and.ac.uk/

20 Quest 1(2) 2 0 0 4

Make the most of the world’s favourite search engine by asking the ‘right’ questions. Here are Eldene Eyssell’s tips for unlocking Google’s (www.google.com) secrets.

Formats you can read – to view an HTML copy of a file as a normal Web page, click on the link “View as HTML” below the page title in blue. This is particularly useful if you don’t have the program (e.g.

CorelDraw, Adobe Acrobat, WordPerfect) to read the original file. It also allows you to avoid viruses that are carried in certain formats, and it loads more quickly.

Search for particular file types – with extensions such as pdf, doc, pps. Type your keyword(s) and then filetype: and the extension in the Search box, e.g. access forms filetype:pdf Find out more – by clicking the “Similar pages” link after a result. This helps you find a large number of resources about a particular topic without having to think of other keywords.

It’s all in the title – if you want to focus on a topic, limit your search to titles (the underlined words in blue that appear at the top of each Google search result).

Type intitle: or allintitle: and your keyword, e.g. intitle:bird watching will find titles containing each of your keywords; intitle:“bird watching” results in titles that contain the exact phrase; allintitle:bird watching South Africa finds pages that have all your keywords in the title, in any order.

Dictionary – find the meaning of a word by typing define into Google’s Search box, followed by your word, e.g. define serendipity. If you want only a list of definitions and no other search results, type in define:serendipity (with no spaces on either side of the colon).

Check your spelling – type the word you’re not sure how to spell in the Search box, hit Enter, and Google will suggest the correct spelling. This is especially useful for checking names and places that don’t appear in standard spell checkers. (Google doesn’t care if you use capitals, small letters, or a combination of both.)

Calculate – Google’s Search box can be a calculator. Use these operators for simple functions: + addition; – subtraction; * multiplication; / division; ^ exponentiation (raise to a power of, e.g. 8^2).

You can also find roots, percentages, trigonometric functions, logs, and much more. Go to www.google.com/help/calculator.html

Convert – use the Search box to convert units of measurement, e.g. type in 39 inches in metres.

Cut down the number of results – and (normally) go directly to a home page, by typing your keyword(s) in the Search box and clicking the “I’m Feeling LuckyTM” button.

Search by category – if you’re not quite sure what keywords to use, go to Google’s Web Directory (directory.google. com). E.g. a search for Mars in the category “Science > Astronomy” gives results related to Mars the planet, not to Mars the god of war.

Search within a site – when Web sites don’t have their own search features. In Google’s Search box, type site, the Web address of the site (without http or www), and the keyword(s). E.g. site:suntimes.co.za global warming will search the Sunday Times for articles on global warming.

Exclude a site – if you’re looking for sites about e.g. space, but don’t want results from NASA, place a hyphen before the command, e.g. space -site:nasa.com.

Keep it all together – Google ignores common words such as and, to, the, a, where. If a word is important to your search, include it by putting a + sign in front of it, e.g. War +and Peace (include a space before the + sign).

Find out who links to whom – by typing link: followed by the URL of a site (not a keyword), e.g. link:www.nrf.ac.za will give you all the sites linked to the National Research Foundation.

Play it safe – avoid adult sites, and make sure that the “SafeSearch” filter is on by adding &safe=on to the search URL. Get the freshest material – by adding &as_qdr=m# to the end of the result’s address (the long string that appears in your browser’s address bar after you have hit the Search button). Change the # symbol to any number from 1 to 12 to change the maximum age of the results in months, e.g. &as_qdr=m6 gives you results that are, at most, 6 months old.

Get it all – by temporarily changing the number of results that Google gives you on a results page. (The default is 10 results at a time.) If you don’t see num= at the end of the Google results’ address in your browser’s address box, then add & to the end (no space) and type in num=x, where x is the number of results you want, e.g. &num=60 Find the original page – by clicking on the “Cached” link. This takes you to the copy Google made when it indexed the page.

The cache is useful when a page has changed and no longer contains something you remember from a previous visit, or when a page has been deleted or its link is broken.

See the full picture – search for 880 million images by clicking the “Images” tab or by going to http://images.google.com. Search as you would for a text search, using file types, sites, advanced search, etc. On the results page, click the thumbnail to see a larger version of the image. ■

Leon Liebenberg reports on state-of-the-art computer modelling processes being developed in South Africa to help improve the manufacture of stronger, safer blades for turbines used in commercial airliners. or three years, Arnaud Malan has worked with new computer modelling simulation techniques to help manufacture aircraft turbine blades more efficiently. His simulations have produced information that will help reduce costs and improve the quality and strength of the blades.

When manufacturers make ‘single-crystal’ blades for turbines for the aeronautical industry, they make each one out of a single crystal, which they ‘grow’ within a specially manufactured ceramic mould. Of paramount importance to the quality of the blade and the time it takes to manufacture it, is the process by which the ceramic mould is dried. The drying times need to be kept short, while ensuring that the shell does not deform or crack in the process, otherwise the result is an ill-formed blade.

We keep looking for ways to make the manufacturing process more efficient and at the same time to improve the quality of the turbine blades. Until recently, we lacked the computational technology with which to model accurately enough the complex drying process involved – which, in turn, would help us to fine-tune the drying time and improve blade quality. Now, however, we have new customized computational software technology developed by Malan together with Professor Roland Lewis (University of Wales at Swansea).

Lewis is a global leader in the field of computational fluid dynamics (CFD) technology, which is now being used as the key technology in a related research and development project at one of the world’s major aerospace turbine manufacturers.

Lewis’s earlier work on CFD codes gave Malan a starting point for simulating the drying process of the ceramic casts – a

F

Above: Single-crystal blades used in the aerospace gas-turbine industry are cast in ceramic shells. The shell drying process is crucial to the cost and structural integrity of the blade.

The numerical modelling of this process enables streamlined production and also helps to pinpoint shell regions that may impair the strength of the turbine blade and its ability to withstand stress.

The figure shows the simulated moisture diffusion around a drying aerospace engine shell-mould.

(Red denotes high moisture content and dark blue denotes low moisture content.)

Picture: Courtesy of the Department of Mechanical and Aeronautical Engineering, University of Pretoria

complex procedure that enables calculation of the best drying conditions (including the right temperatures and air flow).

Malan’s contributions include improving existing advanced numerical techniques, so that the drying problem and surrounding fluid flow may now be modelled effectively and accurately. Programming techniques were also developed to enable the numerical technology to be transcribed into the high performance computer code needed for simulation purposes.

His work stands to benefit high-tech aeronautical and materials industries worldwide – indeed, wherever it is useful to model the drying of complex materials.

Preliminary benchmark applications range from the drying of construction materials to that of foodstuffs. The developed software offers a very high degree of accuracy, and could help us to live healthier as well as safer lives. ■ For details of the technologies developed see: A. G. Malan and R. W. Lewis (2003), “Modelling coupled heat and mass transfer in drying capillary porous materials”, Communications in Numerical Methods in Engineering, vol. 19 (2003), pp.669–677.

Professor Leon Liebenberg and Dr Arnaud Malan are in the Department of Mechanical and Aeronautical Engineering, University of Pretoria.

Quest 1(2) 2 0 0 4 21

Meteorological station on the eastern part of Marion Island. Low-growing vegetation covers the lowland regions and the large red hills are scoria (volcanic ash) cones, probably only a few thousand years old.

Valdon Smith explains how South Africa’s Prince Edward Islands help us to understand effects of climate change on ecological processes and whole ecosystems. outh Africa’s two subAntarctic islands (Marion Island and, 22 km away, the smaller Prince Edward Island) are getting warmer, drier, and sunnier each year. The changing climate affects the islands’ plants and animals, which evolved in cool, humid conditions. It also helps destructive alien species to invade the islands.

S

The sub-Antarctic region has six islands or island groups in an area of the Southern Ocean between about 45 and 55 S. They include the Prince Edward Islands, which are situated about 2 100 km south-east of Cape Town.

Map and photographs: Courtesy of Valdon Smith

22 Quest 1(2) 2 0 0 4

Biodiversity in island ecosystems Ecosystems develop differently on oceanic islands than they do on continents. Continental ecosystems can draw on a large pool of species, whereas biodiversity on oceanic islands is low.

Marion and Prince Edward Islands (together known as the Prince Edward Islands), for instance, were never connected to, or even near, any continent, so they have relatively few species of animals and plants, which somehow reached

the islands over long distances across the ocean.

Many important functional groups of animals – such as cud-chewing buck and deer, and the predatory cats and dogs so characteristic of continents, especially Africa – are not indigenous to these islands. Nor are frogs, reptiles, rodents, or rabbits. Even the insect fauna is species poor, although in some habitats those few species that exist can reach high numbers.

How does this low biodiversity, and the absence of important functional groups such as herbivores and carnivores, affect ecological functioning on the islands?

Ecological functioning The flow of energy and the cycling of nutrients determine an ecosystem’s ecological functioning. Energy reaches an island as sunlight, which is fixed by plants and results in their growth.

The amount of vegetation growth each year (that is, the ‘annual primary production’) is high

Above: Rainbow over the south-east coast of Marion Island. The black lava rocks are surrounded by vegetation consisting of hardy fern species. The volcanic cinder cone in the background is Green Hill.

The Prince Edward Islands: some facts The Prince Edward Islands (Marion Island and Prince Edward Island) originated as undersea volcanoes only about half a million years ago, long after the continent of Africa split from Antarctica and migrated north to its current position. They are among the warmest of the sub-Antarctic islands, with one of the most thermally stable climates on Earth.

Warmest month: February (7.8 C) Coldest month: August (3.7 C) Annual mean temperature: 5.6 C Average difference between daily minimum and maximum temperatures: 1.9 C Average annual total rainfall: 2 326 mm Average daily sunshine: less than 4 hours Winds: gales occur on about 100 days a year Precipitation (rain rather than snow): high Vegetation: well developed, including flowering plants; no trees or shrubs.

Above: The south-east part of Prince Edward Island. The vegetation in the foreground, called fellfield, consists of flat cushions of Azorella selago on lava and volcanic ash.

litter is partly broken down in the animal’s gut and egested in a form that is easier for soil microorganisms, such as bacteria and fungi, to break down further. Insects and earthworms, therefore, are crucial to the processes of decomposition and nutrient cycling. On Marion Island, it has been estimated that they make available up to 88% of the nutrients needed by some vegetation types there.

The insects and earthworms are cold-blooded, so their activity depends strongly on temperature.

The increasing temperatures occurring at the islands should bring higher rates of litter consumption and hence of nutrient release and plant production. But destructive alien predators can get in the way.

Climate change on Marion Island

House mice House mice show just how destructive an invasive alien organism can be to an island’s biota and ecosystem. Mus musculus (the same species we find in most houses the world over), first recorded

▲ ▲

on the Prince Edward Islands because they have no dry season or bitterly cold weather to stop plants from growing, so substantial amounts of nutrients are needed. Climatic warming should increase plant productivity and the demand for nutrients. But will it?

In most ecosystems, herbivores eat the plants and excrete some of the nutrients – in this way they recycle nutrients and make them available for the plants to re-use. Without herbivores, nutrients taken up by growing plants remain trapped in the plant material, which dies to form plant litter.

Decomposition of that litter releases the nutrients in a form that can be taken up by plants again. So nutrient recycling on the islands occurs mainly through decomposition, rather than grazing.

In cold, wet island soils, however, decomposition (and, therefore, nutrient release) is slow, unless helped in some way. Insects (especially the larvae of moths, weevils, and flies), snails, and earthworms assist by feeding on plant litter. This

■ Annual rainfall has decreased: the 1990s was the driest of the five decades in which precipitation has been measured.

■ Annual mean air temperature on Marion Island and annual mean sea temperature around it have increased by 0.04 C each year since 1969.

■ Annual total sunshine hours increased by an average of 3.3 hours per year between 1951 and 2003.

Quest 1(2) 2 0 0 4 23

Top right: Club-mosses, primitive plants that were dominant worldwide 360–380 million years ago.

Top left: Moss species occurring at higher altitudes on the islands, able to withstand the chilly drying wind.

Above: Small invertebrates.

Right: Kerguelen cabbage. ▲

Ancient cabbages under threat A victim of invasive alien species is the Kerguelen cabbage (Pringlea antiscorbutica), found on only four sub-Antarctic island groups, including the Prince Edward Islands. It is one of the last (perhaps the only) remaining relict* of a once extensive circum-Antarctic flora, and was eaten by sailors, sealers, and whalers to prevent scurvy. On Marion Island, its distribution and abundance has declined alarmingly over the past 20 years because of invasive alien biota: ■ The European slug (Deroceras caruanae) was introduced to the island in the mid-1960s. Its population increased and spread widely in the 1990s. The Kerguelen cabbage is one of its favourite foods.

■ The diamondback cabbage moth (Plutella xylostella L.), a major pest of crucifers (cabbages, cauliflower, Brussels sprouts), arrived in 1986. The cabbage is its only host plant on the island.

■ Botryotinia fuckeliana, the fungus that causes grey mould rot in crucifers and other vegetable crops, arrived through vegetables sent as food for staff on the island (this practice has been discontinued). It has infected many stands of Kerguelen cabbage, and whole plants are collapsing into black slimy residue. * Relict n. An animal or plant known to have existed in the same form in previous geological ages.

Definitions Biota: the animal and plant life of a region.

Functional groups of plant and animal species are groups of species that ‘do the same sort of thing’ ecologically, e.g. herbivores, carnivores, floating plants, plants that climb over forest trees, succulents.

Biodiversity: species-richness.

Annual primary production: the amount of vegetation growth during a year.

24 Quest 1(2) 2 0 0 4

on Marion Island in 1818, was probably introduced

by Danish sealing companies.

These mice feed mainly on adults and larvae of moths, weevils, and flies, and on earthworms and snails, the very same invertebrates that are so important in driving the island’s ecosystem functioning. Mice can consume up to 194 g (dry mass) of these invertebrates per hectare each day.

They can eat as much as between 1 and 6 times the average population of a particular prey species annually. These high consumption rates severely reduce the island’s invertebrates, most of which take a long time to reproduce. The moth larvae, for instance, need several years to transform into adults.

We see the effect of the mice very clearly by comparing the invertebrate populations of Marion Island with those on nearby mouse-free Prince Edward Island, whose insect populations are far greater in size, structure, and composition.

Other species also suffer from the mouse predators. The maximum body size of certain weevils is diminished, for instance, because the mice feed preferentially on adults of a specific size.

Another victim is the lesser sheathbill (Chionis minor): the only non-migratory bird species on the island, it relies on soil macroinvertebrates as food in winter. From the mid-1970s to the mid-1990s, the sheathbill population on Marion Island decreased by 23%, whereas that on Prince Edward Island remained stable. Mice also affect the sedge (Uncinia compacta), removing its seed long before it ripens.

As a result, the sedge forms a far greater component of the vegetation on Prince Edward Island than on Marion Island.

More insidious, and probably even more profound, is the destructive effect of house mice on the ecosystem as a whole as they remove cardinal agents of energy flow and nutrient cycling on the island.

We estimate, for instance, that predation by mice on moth larvae alone prevents the consumption of 1 000 kg plant litter per hectare per year, a decrease of about 40% compared with what would be consumed by more insects in the absence of mice. Since it was first studied in 1979/80, Marion Island’s mouse population appears to have increased – in one habitat it doubled between 1979 and 1992 – possibly thanks to climatic warming and/or the eradication of the island’s feral population of domestic cats in the early 1990s.

Increasing mouse populations translate into greater destruction of invertebrates and lower rates of nutrient cycling. This makes fewer nutrients available to plants and it lowers primary production. Even more important, it

reduces the nutrient quality of the plant material, which, in turn produces low-quality litter that decomposes even more slowly.

Ecological laboratories Marion and Prince Edward Islands are ideal ‘ecological laboratories’ for studying effects of climate change, because global warming is especially intense in the sub-Antarctic region and because their ecosystems are relatively simple and sensitive to change.

These two jewels in the sub-Antarctic research crown have already produced a South African research output of some 800 publications and 40 Ph.D. and master’s theses. They will continue to play their part in the work of the new DST Centre of Excellence for Invasion Biology (see p. 45). ■

For the origin, prehistory, biology and ecology of Marion Island, consult V.R. Smith, “The environment and biota of Marion Island”, South African Journal of Science, vol. 83 (1987), pp.211–220, and for the most recent news of changing climate and its implications, see V.R. Smith, “Climate change in the sub-Antarctic: An illustration from Marion Island”, Climatic Change, vol. 52 (2002), pp.345–357. The plants, animals, and geology of the island are described in the 37-chapter book, edited by E.M. van Zinderen Bakker, J.M. Winterbottom, and R.A. Dyer, called Marion and Prince Edward Islands (Cape Town: A.A. Balkema, 1971). You will find details of alien species, plants, and animals introduced to Marion Island in B.P. Watkins and J. Cooper’s “Introduction, present status and control of alien species at the Prince Edward Islands, sub-Antarctic”, South African Journal of Antarctic Research, vol. 16 (1986), pp.86–94.

A pair of grey petrels.

Domestic cats can destroy island ecosystems.

Valdon Smith and Marthan Bester explain how Marion Island got rid of these dangerous predators.

irst the house mice (Mus musculus) were brought to Marion Island, then the cats (Felis catus) to catch them. But instead of eliminating the mice, the cats hunted larger prey that they could catch more easily, such as burrowing seabirds. On all four of the six subAntarctic island groups where cats have arrived and multiplied, they have devastated seabird populations.

Domestic cats are among the worst of all invasive species and have caused a large

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Penguin, Albatross & Giant Petrel Fertilizer Co. We estimate that these surface-nesting birds bring the following to Marion Island each year: ■ 3 600 000 kg guano* ■ 512 000 kg nitrogen† ■ 95 000 kg phosphorus ■ 183 000 kg calcium *

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This amount contains 52 billion kilojoules of energy = enough energy to heat 125 million litres of water from 0 to 100 C or energy in petrol to drive 35 medium-sized cars at 80 kph non-stop for a year. † The amount of nitrogen in 8.2 million kg of 2:3:2 fertilizer.

proportion of global extinctions, especially on islands. We estimate that their hunting is responsible for the extinction of at least 33 bird species that occur on only a specific island or island group, as well as mammals and reptiles, including iguanas and the giant La Gomera lizard.

Cats are opportunistic predators with a varied diet. They breed prolifically and can live in very dense populations (for example, up to 14 cats per km2 on Marion Island). Because island animals (and plants) have generally evolved without competitors and predators, they do not have the means to deal with them.

By decimating bird populations, cats upset the ecological functioning on islands. When seabirds feed in the sea and deposit their guano, eggshells, and moulted feathers on the island, they provide energy and nutrients (see box), so their destruction by cats has widespread implications.

Burrowing birds are essential for maintaining the nutrients for several of the island’s plant community types such as tussock grasslands.

A house mouse on Marion Island.

Photograph: Jan Crafford

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How did the cat problem start on Marion Island, and how was it solved?

1818/1819 – Female cat put ashore from the sealer, General Gates, and becomes feral (wild).

That cat has no offspring and the island is cat-free for the next 128 years.

December 1947 – Occupation party, after annexation, borrows a cat from the ship that comes to relieve them; the cat snuggles up with the mice instead of eating them, so she’s returned to the ship.

January 1948 – First meteorological observation team brings warm clothes, tinned food, gramophone and records, books, ping-pong table, and a radio to contact home once a month; they bring no cat to deal with the plague of mice.

March 1949 – Third team to the island imports an orange-striped tabby tomcat and a black and white female cat.

August 1949 – Team brings three sibling kittens.

1965 – Cats are common around the island edge.

1974–1976 – The South African Scientific Committee for Antarctic Research (SASCAR) begins a seven-phase cat eradication programme.

Phase 1: study of the cats’ demography, breeding biology, and diet. First proper census in 1975 counts approximately 2 140 cats. The cats eat about 450 000 birds a year, mainly Salvin’s prions (Pachyptila vittata salvini), soft-plumage petrels (Pterodroma mollis), Kerguelen petrels (Pterodroma brevirostris), great-winged petrels (Pterodroma macroptera), and blue petrels (Halobaena caerulea). Even penguin remains are found in stomach contents. Mouse remains are found in only 16% of the stomachs.

Phase 2: assessment of control methods.

Scientists test biological control with feline panleucopaenia (FPL) virus, which produces gastroenteritis-type symptoms in cats and rapidly leads to death; it does not affect birds or seals.

1977 – Cat population reaches about 3 405, increasing by 17–23% a year.

Phase 3 begins in March, when 96 cats are

inoculated with FPL and released from helicopters round the island.

Phase 4: monitoring the effect of FPL and testing other methods of control (such as trapping, poisoning, hunting with dogs, and shooting). Cat population decreases by 54% within 18 months.

1981 – Phase 5: further study of the cats. Pilot trial begins to test the time- and cost-effectiveness of hunting with shotguns.

1982 – SASCAR finds that cat population has declined by 26% a year; about 615 cats are left.

They develop immunity to FPL, so there is no significant decline in 1983.

The interior mountainous region of Marion Island showing the three main lava types. The black lava in the foreground formed the mountains and erupted after the last glaciers disappeared (about 11 000 years ago). The grey lava in the middle is more than a quarter of a million years old, and the red hills are cinder cones – volcanic ash deposits that erupted at the same time as the black lavas.

1986–1988 – Phase 6: full-scale, continuous, and intensive hunting at night by 8 two-man teams kills 458, 206, and 143 cats over three summers: hunting alone cannot eliminate all the cats.

1989 – Phase 7: experimental trapping and hunting. Trapping accounts for 54% of cats killed in 1989/90 season and 91% in 1990/91 season.

Poisons are investigated, and sodium monofluoroacetate is chosen because it is odourless, tasteless, biodegradable, and results in quick death.

May 1991 – Large-scale poisoning campaign begins, plus hunting and trapping. First 12 000, then 18 000, day-old chicken carcasses injected with the poison are placed round the island.

July 1991 – The last cat is trapped.

Marion Island, at 290 km2, is by far the biggest of 48 islands from which cats have been eliminated (the next largest is the 28 km2 Little Barrier Island off New Zealand; most are smaller than 5 km2). The research accompanying the eradication programme, and hard-won practical experience and lessons learnt, are helping efforts to eradicate cats on other sub-Antarctic islands (for example, by the Australians on Macquarie Island and by the French on the Crozet Islands and some of the smaller islands off the Kerguelen Archipelago). The Marion Island ecosystem is far better off without cats – the breeding of the burrowing bird species has already improved and the tussock grasslands are expected to return. ■

British pussy cats In 1997, 986 tame cats were monitored for five months to see what prey they brought home. The results (excluding prey caught that was not brought home) show that an estimated 9 million British domestic cats bring home: ■ 57 million mammals ■ 27 million birds ■ 5 million reptiles and amphibians.

For more on the problem of cats on 48 islands, read M. Nogales et al. “A review of feral cat eradication on islands”, Conservation Biology, vol. 18 (2004), pp.310–319. For a detailed but easy-toread review of the South African programme, consult M.N. Bester et al.

“A review of the successful eradication of feral cats from sub-Antarctic Marion Island, Southern Indian Ocean”, South African Journal of Wildlife Research, vol. 32 (2002), pp.65–73.

Quest 1(2) 2 0 0 4 27

A rare view of the whole outline of Prince Edward Island from the base station on Marion Island (normally obscured by inclement weather).

To this day, few people know about South Africa’s overseas territories. Valdon Smith describes the hasty and secretive events leading to our acquisition of the Prince Edward Islands.

ntil the mid-20th century, nobody took much interest in the Southern Ocean islands, except the sealers and whalers who exploited them in the 18th and 19th centuries. They didn’t advertise their harvesting areas, so we know little about who visited or inhabited our two islands in those early days.

The first recorded landing on the larger one was in 1803 by sealers who found signs of earlier occupation, probably by other sealers. By the mid-19th century, sealers knew the pair as Marion Island and Prince Edward Island.

In the 19th and early 20th centuries, shipwrecked parties spent up to several months there. Best documented were the stays of an emigrant ship, the Richard Dart, and sealer ships such as the Maria, the Solglimt, and the Seabird. No country explicitly claimed ownership, however. It’s been argued that Britain implicitly assumed ownership by granting leases to gather guano deposits (there never were any) there in the early 1900s, but, in fact, the British government was issuing licenses for whaling, sealing, guano and mineral collecting on almost all the Southern Ocean islands.

U Early sightings and namings 1663 – Barent Barentszoon Ham (Dutch East India Company) travels from the Cape of Good Hope to Java, sights the two islands, names the larger one Maerseveen and the smaller one Dina, but reports them as being almost 700 km north of their actual location. For a century nobody can find them.

1772 – French explorer/ adventurer Marc Joseph MarionDufresne rediscovers the islands, names the larger one Terre de l’Espérance (Land of Hope), the smaller Île de la Caverne (Isle of the Cave), and, collectively, Îles des Froides (The Frigid Islands).

Four years later – Captain James Cook sees the islands.

Not knowing they’re the ones discovered by Marion-Dufresne, he names them the Prince Edward Islands.

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Tactical thinking Developments in arms (especially missile) technology from World War II onwards made

governments realize that long-range warfare encompassing the entire globe was now possible.

Islands in the Southern Ocean became tactically significant. So did ownership. Britain, especially, was threatened, as Chile and Argentina disputed her right to occupy the Falkland Islands, South Georgia, and parts of the Antarctic Peninsula.

The then Union of South Africa owed allegiance to Britain, and their two governments realized that the Prince Edward Islands were vulnerable to foreign ownership claims. Flagraising ceremonies on the other British islands in the Southern Ocean had at least indicated some claim to sovereignty, but no such event had been recorded on Marion or Prince Edward Island.

The sealing and guano-collecting concessions granted to English or South African companies had been abandoned, so no occupation of the islands supported any claim to possession. The late 1940s brought rumours of countries taking an interest. In December 1947 two ships of different nations with no previous record in Antarctica were known to be steaming south, and suspected of planning to claim occupation and legal possession of unoccupied territories in the area.

Hush-hush High-level talks between South Africa and Britain culminated on 17 December 1947 when South Africa’s prime minister, General Jan Smuts,

The research and supply vessel, the S.A. Agulhas, which services South Africa’s Antarctic and sub-Antarctic bases, seen here off Marion Island.

ordered immediate annexation of both islands.

Within 12 days, a naval frigate, the HMSAS Transvaal, was equipped and dispatched: proclamations of intent to annex were read out on Marion Island on 29 December 1947 and on Prince Edward Island on 4 January 1948.

So secret was the enterprise (known as Operation Snoektown) that, when the Transvaal left Cape Town, only the captain, Lieutenant Commander John Fairbairn, knew its destination and purpose. His crew was not told till they were at sea.

Back home, it also stayed top secret, despite three further ships going to the island, the hiring of personnel (from as far away as Tristan da Cunha) to build and man a base station on Marion Island, and the purchase of equipment.

Though many people were involved, only a few top-ranking politicians, civil servants, and defence force personnel understood the true objective.

Press speculation and formal annexation The press paid close attention. On 3 January 1948, a day before the proclamation, newspapers reported that Prince Edward had already been annexed. Press reports followed, on 6 January, of “an official” (unspecified) communiqué in London stating that Britain had authorized the Union government to occupy the islands.

Government confirmation came on 8 January, when Prime Minister Smuts answered questions from the press. Stating explicitly that there was no immediate military reason, he admitted to the annexations. These were formally announced by Governor-General G. Brand van Zyl when he opened parliament on 17 January. His reasons were the intensifying interest by other countries

in the South Pole region, protection of the Union’s future interests, and the need for weather stations.

The mystery continued, however. When the Transvaal returned on 10 January its company was sworn to secrecy before being allowed to disembark. When the coastal steamer Gamtoos left Cape Town with the base-building supplies on 12 January, her destination was not disclosed.

Possibly the government was waiting for the party at the islands to proclaim the annexations formally, together with their intention to occupy the islands, which they did on 24 January.

The proclamation was published in the Government Gazette of 30 January and the annexations became effective in October with the Prince Edward Islands Act, Act 43 of 1948.

Marion Island has been occupied permanently

by South African research and logistic personnel since February 1948. There is no permanent occupation of Prince Edward Island. ■ Professor Valdon Smith is in the Department of Botany and Zoology at the University of Stellenbosch. He has conducted research on the Prince Edward Islands since 1971.

For a popular account of the history and annexation of the Prince Edward Islands, by a maritime journalist who visited the islands shortly after their occupation, read J.H. Marsh’s No Pathway Here (Cape Town: Howard B. Timmins, 1948). You’ll find the text of the proclamation in “The South African Proclamation on the Prince Edward Islands”, South African Government Gazette Extraordinary (30 January 1948) and also in The Polar Record, vol. 5, nos. 35/36 (1948), pp.243–244. The establishment of the weather station is described by the leader of the first team to winter on the island, Alan B. Crawford, in “Establishment of the South African meteorological station on Marion Island, 1947–48”, The Polar Record, vol. 5, no. 40 (1950), pp.576–579.

The proclamation of provisional occupation of Prince Edward Island.

This document was housed in a brass cylinder made from a Bofors antiaircraft gun cartridge case and placed under a flagpole in a cairn of stones in front of a cave on the island. Since this photograph was taken in 1972, the document and the case have disappeared.

Quest 1(2) 2 0 0 4 29

Photograph: Cyclops

Peter Cleaton-Jones describes research at Wits’s Dental Research Institute (DRI) that has helped South Africans keep their teeth healthy.

AWAY WITH ave your teeth been straightened with orthodontic brackets? Have you used fluoride to protect your teeth against decay? Have you had cavities filled recently? If you answer ‘yes’ to any of these, you may unknowingly have benefited from some of the research conducted over the past 50 years at the University of the Witwatersrand’s Dental Research Institute (DRI).

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Golden Jubilee In 2004, the Dental Research Institute (DRI) at the University of the Witwatersrand celebrates 50 years of quality research. At the jubilee party at the Museum of the History of Medicine, two sets of 12 volumes of more than 600 peer-reviewed scientific articles published by the DRI in scientific journals in South Africa and abroad were presented to the Medical Research Council (MRC) and University of the Witwatersrand (Wits) for their archives.

The DRI was formed in 1954 as a joint unit between the then Council for Scientific and Industrial Research (CSIR) and Wits, to undertake research on matters affecting the health and functioning of the mouth. In 1969 the CSIR’s role was taken over by the MRC, but the research direction continued.

There have been four directors (James Irving, Jan Dreyer, Hugo Retief, and Peter Cleaton-Jones). Staff and postgraduates (106 master’s degrees and doctorates have been completed) have worked with countless collaborators in South Africa and overseas to build the DRI’s fine international reputation.

The wide-ranging research programme over the years has included studying how bone calcifies, how best to do reconstructive facial surgery, and how to predict likely trends in dental caries (the scientific name for dental decay).

For details of current research at the DRI, visit www.wits.ac.za/fac/dental/dri.html

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tooth decay!

Smiles all round Dentists use orthodontic brackets to make crooked teeth straight. These small fittings are placed onto a patient’s teeth, allowing spring wires between individual teeth to straighten them gradually over a period of several months to years. In the 1970s, DRI scientists conducted pioneering research on how to stick these brackets directly to teeth, making them more comfortable and less awkward to wear.

Before that time, brackets were welded to stainless steel bands that would be cemented completely around a tooth. The fittings looked ugly, and the thick metal band between teeth limited the amount of space a dentist or orthodontist had available for tooth movement. Placing a bracket directly onto the tooth would improve appearance, and all-important space would become available by removing the metal band between the teeth. To enable good adhesion, though, researchers needed to determine what type of adhesive should be used and just how the tooth surface needed to be prepared. The research in the DRI and in other centres in the USA and England was successful, and modern brackets on teeth are a great improvement on those of the past.

Fluoride for strength One property of the trace element fluoride (called a trace element because only small amounts are needed by the

body) is that it strengthens teeth by getting into the calcified crystals (hydroxyapatite) of the enamel and dentine (the hard parts of a tooth). This strengthening makes teeth more resistant to acid, and, in turn, reduces dental caries.

In 1966, DRI staff took part in a South African governmental commission of inquiry, set up to examine the safety and usefulness of regulating fluoride in drinking water in the interests of public health. Its report came out in favour of using fluoride.

Since then, the DRI has studied the effects of fluoride, and our researchers support fluoride treatments directly on teeth as well as fluoridation of drinking water at a low concentration of between 0.5 and 0.7 parts per million.

But too much fluoride causes fluorosis, a condition in which teeth become discoloured. This happens in areas such as the Northern Cape, North West province, and Namibia, where the water has a naturally high concentration of the element, and where levels of fluoride in borehole water (between 1.5 and 3 parts per million) can be high enough to produce staining and pitting.

We have discovered that, for the same concentration of fluoride in the drinking water, fluorosis in Namibia is worse than in South Africa. This is probably because more water is drunk in the dry Namibian climate, which increases a person’s total fluoride intake.

AWAY WITH

Now... Modern orthodontic brackets bonded directly to teeth.

tooth decay!

And then ... Previous bonding of orthodontic brackets to teeth.

Top tips for healthy teeth ■ Don’t eat snack food more often than five times a day (i.e. at breakfast, lunch, supper, and two teatimes).

Evolving concepts of factors that cause dental caries

■ Do clean your teeth at least twice a day – last thing at night before you go to bed, and directly after breakfast.

■ Do use toothpaste that contains fluoride (unless you’re in an area where fluorosis is a problem).

Changing rates of tooth decay

1960s concept

What causes dental caries?

To find out why rates of dental caries are changing we need to look at causes. Centuries ago people believed that tooth worms were responsible for the disease. Modern theory, however (dating from the end of the 19th century), says that bacteria in the mouth break foods down into acids that remove minerals from the tooth; then enzymes from the same bacteria digest exposed tooth tissue.

As research has developed, so also has our concept of the interacting factors that cause tooth decay. In the 1960s, three simultaneous factors were considered: the tooth itself, food to be digested, and bacteria to do the digesting. If any of these could in some way be controlled, there was potential to reduce the rate of disease. By the 1980s it was realized that the time during which the three factors interacted played an important role. For instance, the longer, and the more frequently, that food is on a tooth, the more acid may be produced by bacteria and the more damage may be caused.

Now the complexity of the interactions is recognized and a fifth factor – an individual’s resistance – is thought to be probably the most important. We know that fluoride can strengthen teeth and make them more resistant to acids; that eating easily fermented foods such as sweets, crisps, and bread less often will reduce the amount of acid formed; and that more research into ways of controlling the number or aggressiveness of bacteria would also

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1980s concept

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2000s concept Food Tooth Bacteria Time Individual’s resistance D Dental caries

Decrease in percentage of 5- to 6-year-old, and 11- to 13-year-old children in sub-Saharan Africa with dental caries (details from publications between 1970 and 2003).

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Epidemiology is the study of rates of conditions in populations. For many years, the prevalence of dental caries in South Africa’s children has been a DRI research focus; information on changing rates helps policy-makers to plan dental services and to spot changes in the disease.

A surveillance study by the DRI, for example, determined rates of dental caries in Germiston nursery school children. With the enthusiastic cooperation of children, parents, and staff of 15 nursery schools, dental caries prevalence (the proportion with dental caries) and severity (number of decayed, extracted, and filled teeth) were measured nine times between 1981 and 2002 in 2- to 5-year-old children. Among the 5-year-olds, there was a steady decrease in numbers of children with decay and in the severity of the condition until 1997; since then the numbers have increased. This pattern has emerged elsewhere in the world, suggesting that there may be cycles in the disease, with rises and falls at intervals of 10 to 15 years.

Another way of looking at trends is to do a statistical evaluation of published surveys, using methods standardized by the Cochrane Collaboration, a group based at Oxford University in England that has branches worldwide (including in South Africa at the Medical Research Council in Cape Town). Published results from surveys over more than 30 years from sub-Saharan Africa were plotted by the DRI: they show that, until 2000, there has been a decrease in the number of children affected by

dental caries in the sub-continent. (It is not clear if the condition is now increasing, as is the case in Germiston.)

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Quest 1(2) 2 0 0 4 31

AWAY WITH

News Q

As America and Europe eat more hamburgers, the Brazilian rainforest pays the price. In the past seven years, Brazil has become the world’s biggest beef exporter. Over 80% of this growth in exports comes from cattle raised within the Amazon, and EU countries are the greatest importers.

The Amazonian rainforest is the largest in the world and home to rich flora and fauna, much of it undescribed and little understood. It is likely to play a crucial role in the ‘health’ – geophysical and biological – of our planet. But the forest is seriously threatened by commercial agriculture, having been cleared at a rate of over 15 000 square kilometres a year since 1997/8. The trees are felled partly for logging, but also to clear land for crop farming and, increasingly, for raising cattle.

A report just released by the Indonesia-based Center for International Forestry Research reveals the concerns and the scale of the problem. The destruction seems likely to continue, as global demand for beef is growing at the expense of poultry, and the Brazilian rancher can raise animals on cheap land and sell at competitive prices. This is a bleak prospect for what is left of the rainforest.

Birds in decline At least 1 200 of the world’s 10 000 known bird species face extinction, says a report presented at the conference of BirdLife International held in Durban in March.

The reasons are environmental changes (such as the loss of natural habitat to intensive agriculture and urban growth), predation by alien species (such as rats and domestic cats), and possibly by climate change that affects montane species. Although birds are widely studied and are the subject of numerous conservation initiatives, the State of the World’s Birds 2004 report concludes that the situation is getting worse in all habitats, especially those of seabirds affected by commercial long-line fisheries.

Wake up and smell the coffee Government scientists in Brazil have mapped the coffee bean genome in a two-year project costing US$2 million. Six Brazilian public institutions, with access to the data before it is made available to companies, will try to develop more diseaseresistant coffee plants that produce better beans.

Reported in the New York Times, 17 August 2004.

Kyoto in fashion “In the spirit of the Kyoto accord, we agreed to dress more lightly.”

Comment by Japan’s finance minister, Sadakazu Tanigaki, on ways in which government officials are helping to cut greenhouse emissions by taking off their jackets at work instead of turning up the air conditioning.

Quoted in The Times, London, 5 July 2004.

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▲

Hamburgers destroy forests

tooth decay!

help. The role of resistance is unclear, but variation in resistance or susceptibility could help explain why, in a family all eating the same food, one child might have a great deal of dental caries yet others may have none at all.

Supporting this concept, epidemiological studies show that about 80% of dental caries happens in 20% of people, probably influenced by their personal resistance. If these susceptible people could be identified early, then scarce resources could be concentrated on this high-risk group. In spite of research in the DRI and elsewhere in the world, it is not yet clear how to identify such people before dental caries actually appears.

Problem bacteria When dental caries rates began decreasing in developed countries during the 1970s this was rightly attributed to increasing use of fluoride. Changing rates in developing countries with low use of fluoride need another explanation, however.

DRI researchers think that the changing rates may be caused by changing virulence in the bacteria responsible for acid production and tooth digestion – perhaps the bacteria are now forming less acid or creating acid at a slower rate.

The bacteria causing dental caries are mainly from the mutans streptococci family. The DRI has isolated five subspecies of mutans streptococci unique to children in the greater Witwatersrand area, and is studying these bacteria for their genetic composition and ability to ferment foods. The typical mutans streptococci subspecies increase acidity in the dental plaque (a mixture of saliva, food and bacteria) on the tooth surface within as little as three minutes of being exposed to fermentable food. If the plaque pH changes from the resting level of about 7.4 to below 5.7, then the tooth surface is damaged

through mineral loss. If our researchers find that the South African subspecies ferment food at a slower rate, this may help explain lower caries rates.

Filling dental cavities When dental caries is present in a tooth, the ideal way to prevent it from spreading is to remove diseased tissue and replace it with a filling material.

For years fillings have been done in dental surgeries using electric or airpowered drills.

Now, thanks to research in Holland, a technique for field use in resource-poor countries is available. It is called the atraumatic restorative technique (ART).

In it, diseased tissue is removed with hand instruments and a glass-based adhesive filling (glass-ionomer cement) is placed into the cavity using nothing more than finger pressure. In some areas of the world, such as in Asia, community members have been trained to apply the technique, in this way relieving pain for many individuals, and sparing dental professionals for more advanced needs. DRI staff have been studying ART in the laboratory, to give further scientific support and credibility to the use of the method in the field, as well as in private practice. They are studying, for example, how voids between filling material and cavity might be reduced.

Dental research throughout the world faces many challenges. Diminishing numbers of scientists work in this field, and we need dedicated researchers to ensure continued progress. There is much to discover about painless and cost-effective ways to deal with tooth decay in developing countries. We have highlights to celebrate, but also diseases to conquer – or at least to control – well into the future. ■ Professor Peter Cleaton-Jones, director of the Dental Research Institute since 1977, is a medically and dentally qualified research scientist with a particular interest in the pattern of dental caries in South African children.

For details consult G. Hayton’s The complete family guide to dental health and treatment (Cape Town: Gallio Publishing, 1998), C.W. Douglass et al., “Changing trends in adult oral disease”, Advances in Dental Research, vol. 7 (1993), pp.1–240, and H. Birkedal-Hansen et al., “Saliva in health and disease”, Advances in Dental Research, vol. 14 (2000), pp.1–102.

For more information, visit these web sites: www.ada.org/public/topics/history/index.asp www.childdevelopmentinfo.com/health_safety/dental_information.shtml www.harvarddentalcenter.harvard.edu/ASP-HTML/dental-info.html www.hsls.pitt.edu/guides/internet/dent?print_format=true www.knowledge.com/Top/Health/Dentistry/Education/Patient www.utoronto.ca/dentistry/newsresources/library/PatientSites.html

Q Interview

South Africa’s Director-General of Science and Technology Dr Rob Adam talks to QUEST. Does it help to have a dedicated Department of Science and Technology (DST) since 2003 and now a dedicated minister?

Having our own minister of science and technology gives us clear leadership, public recognition, and branding – airtime and visibility. Combining arts, culture, science, and technology in one department* was never properly understood in South Africa. The stakeholders are different, the issues are different.

Science and technology (S&T) is a high priority with an increased budget. Where does the money go and what is the DST’s role?

We’re not the only source of S&T or research money.

Science is cross-cutting, and other departments – agriculture, transport, defence, health – also have budgets.

We see ourselves as leading with the leading-edge stuff.

Without us, the biotechnology programme wouldn’t exist: pockets of work would happen unevenly in health, agriculture, and elsewhere, but not this co-ordinated drive.

There’ll also be nanotechnology; technology platforms to support the hydrogen economy; space science.

Other departments do sectoral work and we build customized interventions to assist – for example, the Pebble Bed Modular Reactor (PBMR) programme. Because of its history, nuclear science in South Africa was isolated from the rest of the system. So we’re starting a targeted PBMR human capital programme to assist the Department of Minerals and Energy and help make sure there’s a proper science base when the PBMR goes ahead. There are other examples.

We develop customized partnerships to make money go further and link it to other money. It’s misleading to look at the DST budget alone, as we have a catalysing side. After this current financial year, we’ll be researching and preparing annual reports on government expenditure on S&T that’ll include what comes from other departments.

We also examine ‘market failure’: if something’s not happening in a field of technology, we pick it up, then look to pass it on to someone who should be doing it. When you’re trying to transform a system, you need to keep parts of it close to you for a while.

What’s in S&T for the younger generation?

The big science projects are expensive and capital intensive – the SALT telescope, the PBMR – but it’s hard to deny how inspiring and iconic they are. You lead people into science by showing them something exciting. You also have to demonstrate utility. If somebody argues that science doesn’t offer career prospects, I’d reply: don’t just look at what science can offer you – look at scientists and track their varying careers. Science is a base; it’s a superb way to learn structured thinking.

Have we enough black scientists in South Africa?

The proportion of black scientists in the science councils was 7% in 1994; today it’s 40%, so changes are happening. But offering a career path is important. For S&T to compete with other opportunities is not easy. It’s hard when a nine-year Ph.D. is the entry level, because there are pressures on people to deliver for their families – to feed them, to send other children to school.

The issue is not only science. But we still have to generate excitement. I recently heard a young black woman passionately declare herself a ‘nanoperson’: nanotechnology is what she cares about.

We have the task to elaborate science in ways that aren’t dull and academic and boring, but that capture people’s attention How can we improve science education in schools?

Changing the whole system is hard to do. The job of the ministry of education is incredibly tough. Saying “we need black scientists” is more manageable. If 3 000 are getting a minimum entry-level good matric pass, doubling that to 6 000 is not so hard.

What should the public know about science?

I think there’s a difference between public awareness, public appreciation, and public understanding. With awareness, we’re not challenged, just made aware.

Understanding may be a bit much to expect – I’m not sure even the scientists understand everything. Appreciation is clearly something to aim for.

Science isn’t easy to access because it’s more abstract than other endeavours – but to preserve the industry it’s in our interests to generate appreciation, and ultimately it helps us.

So does making science accessible to decision-makers, who have direct connections with the public. We have the task to elaborate in ways that aren’t dull and academic and boring, but that capture people’s attention and lead them to interesting ways of thinking about the world. ■ * Department of Arts, Culture, Science and Technology For more consult South Africa’s National Research and Development Strategy (Pretoria: Government of the Republic of South Africa, 2002) and National Survey of Research and Experimental Development [R&D][2001/2 Fiscal Year]: High-level key results (Pretoria: Department of Science and Technology, 2004); read Science and Technology in South Africa: Progress and achievements in the first decade of democracy, 1994–2004 (Pretoria: Department of Science and Technology, 2004); and visit www.dst.gov.za

Quest 1(2) 2 0 0 4 33

Mathematics Q

Why should we bother with mathematics in South Africa?

George Ellis gives a whole range of reasons. nderstanding patterns is the central business of mathematics – the patterns underlying numbers and measurements, spatial patterns (geometry and shape), and patterns in time (how quantities change with time). Mathematics is a way of making invisible patterns visible by searching for the mathematical relations between quantities that we have measured. Understanding how abstract symbols (numbers, equations, inequalities) can be used to represent these different kinds of pattern and the relations between them is useful to us in at least four different ways.

First, we need mathematics to understand the world and the universe. It underlies our impressive understanding of astronomy, of physics and chemistry (the behaviour of the particles and forces underlying all the structures we see around us), geology (the forces that shape the Earth, mountains, and rocks), weather patterns (which profoundly influence our welfare, particularly by affecting farming), and

U

Mathematics is a way of making invisible patterns visible – understanding these patterns is its central business. many aspects of biology and medicine. The way these forces work and their impact on the world are represented by mathematical models. So anyone who wants to become a scientist must have a good understanding of mathematics.

Second, it is essential in making technology and society work. All of engineering and technology depends on understanding quantitative relations. Quantitative analysis is essential in the safe, reliable, and cost-effective design of buildings, bridges, roads, cranes, aircraft, motor cars, refrigerators, and so on. What about the tension between cost and safety? (For example, how strong must I make a bridge over a river for it to be safe for buses and trucks? How deep must the foundations of a building go so that it will not fall down?) So anyone who wants to be an engineer must also have a good mathematical knowledge.

Modern societies are also based on very complex economies, involving communication and transport systems, industries, and agriculture, which all affect the environment and depend on water supply, energy sources, and many other resources, and need efficient waste disposal. Planning

how to make this all work in the future also involves mathematical models. (For example, how many dams will we need to supply water to Cape Town over the next 50 years?

Will we need to build more sewerage plants to service the growing population? How many schools will we need?) So making important decisions for society also involves mathematics.

Third, mathematics is important in planning and running your life and any sort of business. You also need to manage resources efficiently. How much should you save for the future, and what is the best way to spend your money now?

(For example, will a big bottle of milk give better value than two small ones? Which detergent gives the best value? Should you buy furniture on a hire purchase scheme or not? What health plan gives the best benefits? Which method of transport gives best value? How much should you spend on education for yourself and your children?) So many choices depend on estimating costs and benefits. Numbers are essential for doing this properly.

Finally, similar issues arise in being a responsible citizen.

When you are asked what local or national government policy will be best for the country, and you take part in democratic discussion about such issues, you will often be given figures that are important in making those decisions.

(How many people are unemployed? What is the inflation rate? What is the country’s debt? How much should we spend on the defence force?) Making informed decisions as a citizen means trying to understand some of these figures and what they mean for the country’s future.

For all these reasons, we need to develop our own mathematical understanding, and to encourage children to get involved in mathematics, and to enjoy it too. Everyone can understand mathematics if it’s well explained, and if you’re prepared to put a bit of work into it. ■ For more read Keith Devlin, Mathematics, The Science of Patterns, Scientific American Library, 1997.

Professor George Ellis is in the Department of Mathematics and Applied Mathematics at the University of Cape Town.

In future articles in QUEST, George Ellis will consider aspects of mathematics, how we learn mathematics, and the question of whether or not we have an inbuilt ‘number instinct’.

Mathematics

in everyday life

34 Quest 1(2) 2 0 0 4

Q Your Q UEST ions answered

What’s the meaning of ‘first’ and ‘second’ cousins and cousins ‘removed’, and how are blood relationships defined?

Some religions forbid marriage within certain ‘degrees of consanguinity’ – how do we calculate these?

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Calculating cousins Cousins

E.g.

A simple calculation will help to distinguish between different kinds of cousins.

■ Let n be the ordinal number (first, second, third, etc.).

■ First cousins (n = 1; r = 0) are separated by (x = 2 1 + 0 + 2 = 4) degrees and could share up to 1/16 (1/24) of their genes.

■ First cousins (n = 1): these share a common grandparent and both are the second generation from the common grandparent.

■ Second cousins (n = 2): these share a common greatgrandparent and both are the third generation from the common ancestor.

■ nth cousins (n > 1): they share a common [(n 1) great]grandparent and are the (n + 1) generation from the common ancestor.

E.g. third (n = 3) cousins share the same great-greatgrandparent [(3 1) great], and both are the fourth (3 + 1) generation from the common ancestor.

■ Second cousins, three times removed (n = 2; r = 3) are separated by (x = 4 + 3 + 2 = 9) degrees and share only about 1/29 of their genes. They could quite happily/safely get married.

Another way to work out x for persons A and B, with a common ancestor Z, is to count up the number of descents from A to Z and then back down from Z to B. (This also works for people who are linked by direct descent, such as parents and children, siblings, and aunts and nieces.)

E.g. the 4 degrees of separation between first cousins Andreas and Bella, whose common ancestor Zenobia is their grandparent = A to parent (1 degree) + to Z (1 degree) + Z to child (1 degree) + to grandchild (1 degree). ■

Removed cousins Cousins are ‘removed’ when the number of generations in descent from the common ancestor is not the same for both cousins.

E.g. in the case of third cousins, twice removed – one may be the great-great-grandchild of the common ancestor (fourth generation), while the other may be the great-great-great-greatgrandchild (sixth generation) of that same ancestor.

■ Let n be the ordinal number (in our example above of ‘third cousins’, n = 3).

■ Let r be the difference in the number of generations (in our example of ‘twice removed’, r = 2).

■ For nth cousins, r times removed – the common ancestor is: a [(n 1) great]-grandparent of one cousin and a [(n + r 1) great]-grandparent of the other.

This formula also works for first cousins r times removed. E.g. for first (n = 1) cousins three times (r = 3) removed, the [(1 1) great]-grandparent of one is the great-great-great-grandparent [(1 + 3 1) great] of the other.

Blood relations Being related to someone ‘by blood’ means sharing a common ancestor. There is a formula for calculating their closeness, or number of ‘degrees of consanguinity’, and how many of their genes they could possibly share.

■ Let x be the degrees of consanguinity, n the ordinal number, and r the difference in number of generations.

■ x = 2n + r + 2. x

■ 1/2 is the number of genes they would possibly share.

Send your questions to The Editor (write S&T QUESTION in the subject line) by e-mail to editor.quest@iafrica.com OR by fax to (011) 673 3683. Please keep them as short as possible, and include your name and contact details. (We reserve the right to shorten or edit for clarity.) We will send you R50 for every question that is published with answers from our experts.

Quest 1(2) 2 0 0 4 35

Q Advertorial

World-class Research and Development at Tuks Department of Mechanical and Aeronautical Engineering The Department of Mechanical and Aeronautical Engineering at the University of Pretoria (Tuks) is the largest in the country. It delivers nearly a third of South Africa's mechanical engineers. The Department's core business is excellent teaching and training of students as well as research of the highest standard. The pursuit of excellence, quality, international competitiveness and local relevance are the hallmarks of this institution. rom an academic staff of 26, 16 have PhD degrees obtained from six different countries. In addition, the majority of staff members have substantial industrial or consulting experience. The Department of Mechanical and Aeronautical Engineering is 45 years old but boasts modern physical facilities – its Sasol Laboratory for Structural Mechanics is recognised as a world-class facility.

Among the Department's achievements count eight SABS Design Awards and numerous other awards for excellence in research and development.

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Contributing to the competitiveness of the country and improving the quality of life of its citizens form an important part of the Department's mission. Research efforts are thus conducted in areas that have a direct impact on the well-being of the industry. Research is conducted within four specialist groups, namely the Dynamic Systems Group, the Design and Manufacturing Research Group, the Thermofluids Research Group and the Multidisciplinary Design Optimisation Group, the latter operates interdisciplinary with the other three research groups.

Dynamic Systems Group

Thermofluids

Multidisciplinary Design Optimisation Group Design and Manufacturing Group

The Department of Mechanical and Aeronautical Engineering of the University of Pretoria has made history by appointing a Departmental Advisory Board to advise the Department on strategic issues that impact on its activities. What makes the board unique is that it comprises of eight very senior mechanical/aeronautical engineers from industry, together with the senior academics and student representatives from the department.

The board will meet on a regular basis and give advice on academic matters (teaching and research), academic quality, local relevance, transformation, international competitiveness, departmental culture, sustainability as well as innovation regarding the underand postgraduate programmes of the department.

Advisory Board members are: Front (from left): Prof Josua Meyer (Head: UP Department of Mechanical and Aeronautical Engineering), Prof Roelf Sandenbergh (Dean: UP Faculty of Engineering, Built Environment and Information Technology), Nicola van der Merwe (UP Student Representative), Giel de Lange (Managing Director: IST Nuclear Power Systems), and Dr Hans NaudĂŠ (Managing Director: Sasol Gas).

Centre: Matie von Wielligh (General Manager: Iron Ore, Kumba Resources); Prof Jasper Steyn (UP), Prof Stephan Heyns (UP), Martin Dohm (VicePresident: Engineering, Anglo American), and Thys Sabbagha (Head: East and West Africa region, Anglo Gold).

Back: Dr Paul Potgieter (Managing Director: Aerosud), Danie Burger (UP); and Dr Stephen Meijers (Chief Executive: Bateman Minerals and Metals Division) Absent: Johan Rall (Consultant: Hansen Transmissions); Prof Jan Snyman (UP); Prof Ken Craig (UP)

Quest 1(2) 2 0 0 4 37

Advertorial Q

Load reconstruction: During structural fatigue testing the response of a structure will often be known but not the forces that gave rise to the observed response. To control and execute fatigue tests these forces however need to be determined.

A test gas turbine combustor from a C130 cargo aircraft, and a computational fluid dynamic (CFD) model showing contours of temperature distribution. Research work also includes the experimental verification of simulation results. Work is also being conducted on the propulsion systems of the Gripen and Hawk military aircraft.

Dynamic Systems Group The Dynamic Systems Research Group is researching techniques to identify the forces by using non-linear structures.

• Vibration monitoring and damage detection: The Group has developed unique monitoring methodologies to deal with situations of varying speed and load which may be used on large mining machinery gearboxes, as well as a methodology for estimating machine tool wear based on vibration measurements only.

• Vibration control: The Group is currently expanding its machine tool wear monitoring work to simultaneously control tool vibration and improve the quality of cut.

• Vehicle dynamics: The development of a two-stage, semi-active, hydropneumatic suspension system to improve ride comfort and handling of off-road vehicles.

• Computer-aided Analysis of Dynamical Systems.

Tundish water model

38 Quest 1(2) 2 0 0 4

Thermofluids Research Group • Heat Transfer Research (Experimental investigation of single-phase transitional regime flow in advanced heat exchangers; modelling and experimental investigation of condensation and evaporation in enhanced tubular heat exchangers; aerodynamic heating of modern missiles; numerical modelling of aerospace related manufacturing technology).

• Electronics Cooling Research (Numerical modelling and optimisation of computer heat sinks).

• Gas Turbine Research (Numerical modelling of gas turbine combustors and nozzle guide vanes; fuel injection optimisation; investigation of transient interaction between the stator-rotor blades and the effect this has on cooling flow and blade life).

• Design Optimisation Research (Continuous casting design optimisation; design optimisation of automotive fuel tanks for sloshing and impact; engine intake design optimisation; variable screening in optimisation; reliability and robustness-based design optimisation).

• Development of computational fluid dynamics (CFD) technology for the modelling and simulation of advanced engineering systems (modelling drying of ceramic shells used for casting aerospace engine blades; development of a fast and accurate Euler solver for the efficient concept design of newgeneration supersonic missiles, development of simulation technology by which to model complex flow through packed bed heat-exchangers.).

The tundish forms a crucial part of the continuous casting process of steel in that it acts as a reservoir, grade separator and as an inclusion particle removal device. The design optimisation process uses Computational Fluid Dynamics (CFD) combined with mathematical optimisation to produce tundish designs that result in cleaner steel and reduced losses due to mixed-grade length.

Q Advertorial Design and Manufacturing Research Group

Multidisciplinary Design Optimisation Group

• Mining Safety (Mechanical device for stopping conveyances during over and underwind; the development of a quiet self propelled rock drill; the development of a dynamic roof support system for tabular stopes; the development of a roof support system for rock fall mines; the development of a universal load indicating device for various roof support systems in mines; the development of an effective light weight pinch bar; research into roof bolts and the various problems associated with roof bolts like over spinning, temperature and spin speed.)

• Integration of appropriate mathematical optimisation techniques with analysis tools in structures, dynamics, fluid flow and heat transfer, in order to facilitate the optimal design of physical systems. ■

Enquiries Prof. Josua P. Meyer, Head: Department of Mechanical and Aeronautical Engineering (jmeyer@up.ac.za) Prof. Stephan Heyns, Head: Dynamic Systems Group (stephan.heyns@up.ac.za)

Dynamic roof support system for tabular stopes in mines.

Prof. Ken Craig, Head: Thermofluids Research Group (ken.craig@up.ac.za) Mr. Danie Burger, Head: Design and Manufacturing Group (danie.burger@eng.up.ac.za) Prof. Jan Snyman, Head: Multidisciplinary Design Optimisation Group (jan.snyman@eng.up.ac.za) Prof. Leon Liebenberg, Public Relations Officer (lieb@up.ac.za) Website www.me.up.ac.za

The Design and Manufacturing Group is developing a Bio Artificial Liver Support System (BALSS), in collaboration with the University of Pretoria's Department of Internal Medicine. The BALSS system, consisting of a bio-reactor housing live liver cells, forms part of a perfusion circuit where plasma from a patient suffering from acute liver failure is pumped through the system and in doing so, supports the liver function of the patient. The Group has already received funding of R9.2 million and has already begun with animal trials. Human clinical trials are scheduled to begin middle-2005.

Literal measurements arm’s length – a distance discouraging familiarity or conflict; in many cultures the human arm is a standardized unit of distance equal to about 70 cm, for example the Italian braccio, the Turkish pik, and the Russian archin. blink – very quickly (“in the blink of an eye”); the average time of a complete human blink is about 300–400 milliseconds (or 3/10 to 4/10 second). It differs from person to person, and other factors can slow this down (e.g. fatigue, medication, disease, and injury to the eye area), so a person’s blink rate can be used for diagnosis or to check a person’s level of alertness.

• Lubrication of diesel fuel.

• Biomechanics (Bio Artificial Liver Support System; tribology of hip joints; characterisation of the human rotator cuff system).

MEASURING UP

Tel.: +27 (12) 420 3104 Fax: +27 (12) 362 5124 Write to Department of Mechanical and Aeronautical Engineering, University of Pretoria, Pretoria, 0002, South Africa

dead-weight – a heavy weight or burden; a dead-weight ton (dwt) is the unit used to measure the difference between a ship’s weight when it is completely empty and its weight when fully loaded with, for example, cargo, fuel, passengers, and crew; it is equal to a metric tonne. hair’s breadth – a very small amount or margin; on average, the diameter of a human hair is 100 µm or 0.1 mm, though it can vary considerably and depends on age, colour, genetics, and other factors. moment – a short time or an instant; a medieval unit of time equal to 1/40 hour or 1.5 minutes. myriad – an indefinitely great number; it originally meant 10 000. shake – very quickly (“in two shakes of a lamb’s tail”); a shake is equal to 10-8 second or 10 nanoseconds. This informal unit of time originated in nuclear physics where the shake is the approximate lifetime of a neutron in an atomic explosion. thimbleful – a small quantity, especially of liquid to drink; about one cubic centimetre or one millilitre. bone-dry – quite dry; a bone-dry unit (bdu) is used to measure the volume of bulk forestry products, such as wood chips, that would weigh 1.0886 tonne (2 400 pounds) if all the moisture content were removed. flock – a number of animals or a crowd of people; in Old English, the flock was a unit of quantity equal to two score or 40. generation – a single step in descent; the average length of time between the birth of a parent and the birth of his or her child is about 30 years. drop – a very small amount; in pharmacy, the drop (gt) is a unit of volume equal to 0.05 ml, i.e. there are 20 drops (gtt) in a ml. (The abbreviation comes from the Latin gutta meaning ‘drop’.) ■

Quest 1(2) 2 0 0 4 39

Viewpoint Q

to be trusted

Is

Some people accept science unquestioningly; others are inherently suspicious. Graham Baker tells QUEST why he’s a supporter. scientists can misbehave. They may, cience and technology (S&T) for instance, fabricate their results, or are the bringers of good things. falsely claim the work of others as They are the world’s most their own, or selectively exclude data, powerful – and most intrusive – or neglect to disclose conflicts of cultural forces. National economies interest, or break ethical codes. The depend on them, so do our very lives. scale of the offence can vary from And scientists deserve our admiration minor errors of judgment to outright and attention. Their achievements are fraud. awesome – they’ve described the largeThe levels of dishonesty are not scale structure of the universe, known. The scientific community deciphered the chemical blueprint of believes them to be relatively low in a some living organisms, and probed the ‘hard’ science such as physics, but inner workings of the atomic nucleus. greater in medical research, for Scientific findings are documented in example, where there may be vested a massive and growing scientific interests in reporting on how well a literature that has global currency. The commercial drug works, or where most successful conclusions become repeating clinical trials (and therefore enshrined as laws, with predictive checking and monitoring them) may value, that offer keys to understanding be difficult. Cases of misconduct have the universe and form the basis of increased through greater pressure to modern technology – Newton’s law of gravitation, for instance.

This proud track record is based on ‘rules’ and conventions by which We can engage best we assess the reliability of with the marvels of scientific pronouncements. For example, we expect the science by consulting the results of a scientific right people, asking the right experiment, and any questions, and taking hypothesis based on them offered in the open literature, to informed decisions. be testable. When an experiment is reported, the method and results have to be presented in such a way that other scientists can repeat the study publish, for instance, for purposes of exactly, to test for accuracy and to see attracting funding, or prestige, or if the replication supports or refutes career advancement. Some fraudsters previous conclusions. have published out-of-the-ordinary Through good behaviour and results, appearing as breakthroughs in astonishing ingenuity, scientists in prestigious international journals. many disciplines have acquired selfClearly, scientists who cheat are confidence and enviably high dangerous, so more and more credibility: they expect to be believed, professional bodies and research and we expect to believe them – far journals have guidelines for ethical more than we expect an economist, conduct in scientific reporting. They say, to understand market forces, or a take these matters seriously because, politician to tell the truth at all times. when fraud is uncovered and made public, other – ethical – scientists, and Individual integrity sometimes entire scientific disciplines, We tend also to assume that scientists’ also come under suspicion. The misdemeanours are not only effects of fraud may have farnegligibly few but even self-correcting reaching, even life-and-death because their assertions can be tested. implications – as when false claims There is the occasional bad apple in are made for the way to treat disease. every walk of life, of course, and

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40 Quest 1(2) 2 0 0 4

What can go wrong It’s not just fraud that can make scientific evidence and knowledge fall short of expectations. Science sometimes appears fuzzy; scientists themselves can hesitate about the significance of their work; they can also disagree.

One problem at the small-scale level is that scientists are specialists, and no single individual, or even group of collaborators, can be expert in more than part of a discipline or project. A climatologist might know something about ocean currents and plankton, for instance, but that’s only part of the ‘climate change’ equation. A panel of experts in different aspects of a field and related disciplines might analyse then synthesize their findings, but their conclusions can at best take the form of a working hypothesis. Another problem is that evidence may be very limited.

For example, there may be only a single fossil of an ancient organism, from which its life history cannot definitively be reconstructed.

Furthermore, scientists are human. It could be career-limiting, for instance, to publish results that contradict those of your boss or of a prominent powerful scientist in the field, or to oppose publicly the commercial policy of a business that finances your laboratory.

At the other end of the scale are concerns so large that they have to be the responsibility of national or even international bodies. An adviser to former US president Jimmy Carter, Amitai Etzioni, sees many of our big S&T problems seemingly getting bigger, and even governments less and less able to deal with them.

Coping with success The problems grow out of the very success of S&T in making the world a better place. Particularly difficult to address are issues about which there is no consensus, and where activities in one part of the world may have serious implications for the rest of the planet.

For example: what’s to be done about atmospheric pollution from industry

Q News

and its possible effects on the global climate? Or about creating and reprocessing nuclear waste? Should there be limits on the creation of GM organisms or on stem-cell research?

Should we worry about the destruction of the Amazonian rainforest and the loss of natural habitats in our own backyards as a result of urbanization and the need to create jobs?

These are difficult questions, even for informed scientists. Answers require technical information – which may not be available or accessible. What’s available may be difficult to interpret or open to debate. Our mathematical models of the atmosphere, for example, offer only approximate climate predictions. Yet farmers still use them for planning.

Access to information may be restricted because of vested interests, which limits scientists’ ability to use it for greater understanding. The results of attempts to sequence the genes of plants and animals are normally, and rightly, made public, but in some cases only after payment, even though some of the research may have been financed by taxpayers. There is also a growing tendency to limit the publication of findings of privately sponsored research at universities.

Not just scientists but policy-makers and members of the public too need to know what to do about scientific issues.

Governments (and, indirectly, those who vote them into power) must decide what to do about greenhouse gas emissions and building nuclear power stations. We as individuals base our daily lives on trust in the technology that surrounds us and we need to know the facts. Do cell phones cause damage to the brain? Do computer screens ruin your eyes? How dangerously do emissions from motorcars, industries, or mines pollute the air we breathe and the water we drink?

As with everything, we need to keep up to date and act responsibly. We have to be on the alert to distinguish the genuine scientist from the charlatan, and what’s known with confidence from what’s speculative. We can engage best with the marvels of science by consulting the right people, asking the right questions, and taking informed decisions. ■ Dr Graham Baker has been the editor of the South African Journal of Science for the last thirty years.

What can science really tell us?

■ A scientific investigation is about

approaches to objective truth, normally expressed in the form of a hypothesis.

■ Much of science deals with probabilities and risk, rather than with certainties.

■ Actions that follow from ‘science’ are only as reliable as the ‘science’ cited to support them.

■ Scientific knowledge can be abused and misused by commercial and political interests.

What questions to ask?

Faced with a scientific pronouncement, you can ask ■ What is fact, what is opinion, what is belief? (The pronouncement should differentiate between them.)

■ What are the factual limits? (How complete are the facts? How accurate? How relevant to the issue?)

■ What legitimate conclusions can be drawn from the facts? (What can’t be concluded because of limited information? What are the implications? What action can be recommended, with what cautions and provisos? What reasons are given for rejecting a prevailing opinion?)

Who provides the answers?

Where can a member of the public, or a government, go for reliable scientific advice? Whom can we trust? What should we expect?

■ An individual expert with integrity and no vested interest in the answer may be sufficient (e.g. an expert witness in a court of law).

■ Beware of ‘authorities’ or celebrities who express judgments outside their area of expertise.

■ A group of experts, with nothing to gain from the analysis, synthesis, or recommendations, can provide an informed range of options (e.g. an academy of science or a specialist professional society operating independently of policymakers, governments, and commercial interests).

■ In some parts of the world, scientists and professional bodies with no hidden agendas make public up-to-date reports and recommendations, based on current local and global scientific research, on matters of concern, debate, interest, and the public good.

See-through progress Glass is what gave western civilization the competitive edge over the rest of the world in the 17th and 18th centuries, claims anthropologist Alan Macfarlane (University of Cambridge, England). The scientific and industrial revolutions could not have happened without it.

Progress in everything from astronomy to medicine to modern genetics depended on glass. Without it there could have been no microscopes or telescopes; no understanding of the solar system by Galileo nor identification of infectious diseases by Louis Pasteur. Glass is an essential component in the barometer, the manometer, the thermometer and air pump, which enabled Jacques Charles and Robert Boyle to derive their laws linking gas to its pressure and temperature, and which in turn made further inventions possible, such as the steam engine, the internal combustion engine, and the gas turbine.

Reported in New Scientist, 11 September 2004 (from Science, vol. 306, p.1407).

How heavy oil was made Oil in many of the world’s largest reserves is difficult to refine because it has degraded over millions of years from light molecules into heavy oil (an acidic, tarry sludge). Till now, geologists have been uncertain about the degradation process: was oxygen required in it, or was anaerobic degradation also important?

Researchers at the UK’s University of Newcastle upon Tyne analysed oil taken from 40 heavy-oil basins around the world and found that each contained anaerobic degradation products called reduced 2naphthoic acids. “We’ve found the smoking gun – clear chemical indicators that it is indeed an anaerobic process,” announced team leader Stephen Larter (now at the University of Calgary, Canada). These results mean that, in time, petroleum engineers could find ways to accelerate the process and generate cheap energy in the form of methane from currently uneconomic heavy oil reserves.

Reported in New Scientist, 18 September 2004 (from Nature, vol. 431, p.291).

Gender (e)quality?

It’s not impossible that women could one day close the gap with men in Olympic performance, suggest researchers. Plotting the winning times of the men’s and women’s Olympic finals for the 100-metre sprint over the past 100 years, they have found performance levels rising steadily, with no indication that a plateau has been reached by either male or female athletes. Moreover, the women are catching up. Extrapolating from the trends and the improving speeds over the last century, the winning women’s 100-metre sprint time could even, by the 2156 Olympics, be lower than that of the men. This simple analysis overlooks influences such as timing accuracy, environmental variations, national boycotts, and the use of legal and illegal stimulants. It could take 150 years to find out if the extrapolation works in practice.

Reported in Nature, 30 September 2004.

Quest 1(2) 2 0 0 4 41

Books Q Ficus bussei (Busse’s or Zambezi fig), Salima, Malawi. This large tree, with a spread of up to 42 m, gives fine shade all year round in the hot areas where it grows.

Its fruits are eaten by humans, as well as by fruit-eating birds, bats, and monkeys. The latex (milky sap) from this tree is used to treat burns and conjunctivitis; it can also be used as a glue. Photograph: John Burrows Drawing: Sandra Burrows

Figs of southern & south-central Africa. By John and Sandra Burrows (Hatfield, Pretoria: Umdaus Press, 2003). o other tree has played such a vital role in the life of Africa as the fig.

It has been cultivated in Asia Minor for at least 6 000 years; the wood of the sycamore fig was used to build the sarcophagi of the pharaohs of Egypt; and the bark of the Natal fig was used for centuries (it still is) for the manufacture of cloth and clothing before the advent of European textiles. The milky sap has medicinal properties, and the fruits have nourished the people of Africa, their livestock, and almost every fruit-eating mammal, bird, and fish on the continent. Under the branches of a fig tree laden with ripe fruits, birds, bats, baboons, monkeys, antelope, and even elephant congregate to feast off its harvest; the myriads of insects attract insectivorous birds. Many tribes in Africa revere fig trees as shrines to their gods and spirits. In their shade, people can rest and socialize.

This volume combines text, drawings, and photographs to present an exquisite and scholarly snapshot of the world of figs in southern and south-central Africa at the beginning of the 21st century. It describes and illustrates all the 10 genera and 66 naturally occurring species in the

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Ficus vallis-choudae (known as false Cape fig or Haroni fig), Masai Mara, Kenya. Fairly common in Malawi, and occurring in swamp forests and along rivers, it grows 25 m tall. Local people eat the fruits in Tanzania, Kenya, and West Africa.

Cheap furniture can be made from the wood and cloth from the bark. Medicinally, it offers remedies for jaundice, vertigo, gastrointestinal complaints, and bronchitis, and is even used as an antidote for poison.

Photograph: Duncan Butchart

42 Quest 1(2) 2 0 0 4

family Moraceae as well as 24 species that have been introduced to the region. The book provides the most comprehensive coverage of figs for any region worldwide.

John Burrows explains what led him and his wife, at their own expense and in their spare time, to travel more than 70 000 km over ten years to examine, photograph, and draw these figs in the wild. “We love exploring out-of-the way places,” he says. “Figs are so imposing, and so well used by humans, animals, and birds. And their biology is so fascinating, with their dependency upon the tiny pollinating fig wasps.”

Without the fig wasp the fig cannot reproduce normally, and the wasp cannot survive without the fig fruit.

Most often, only a single wasp species can pollinate a particular fig species.

So, in areas of Africa where natural vegetation is being cleared away, fig trees must be preserved – not too far from each other – so that sufficient trees can remain at distances that the fig wasp can travel.

A further motive was controversy about the scientific naming of figs, says Burrows: “We knew that many name changes had been based upon the evidence of dried herbarium

Q Books New books

Drawing: Sandra Burrows

Above: Ficus cordata (or Namaqua fig), Northern Cape, South Africa. It grows on rocky hillsides or cliff-faces, and feeds birds and animals in relatively arid desert areas. It is the first indigenous fig recorded in the southern African literature, by Dutch artist Hendrik Claudius who accompanied Simon van der Stel on an expedition in 1685. More recently, farmers brought goats and sheep to the West Griqualand area. The farmers destroyed the jackals and black eagles that preyed on their livestock – and on the local dassies. Now the dassie population is out of control, and puts such pressure on these figs as a food source that large numbers of these trees are being destroyed. Photograph: John Burrows Left: The authors, Sandra and John Burrows.

specimens, which don’t always reveal the true picture of relationships between plants. So we needed to do an in-depth study of the figs growing naturally in the field, rather than confining ourselves to the figs in herbaria or botanical gardens. This would tell us about their ecology and biology, and also shed light on the problems of fig names: only by becoming familiar with a group of plants over much of its range, and with the natural variation that species display, can we delimit species within a group of plants.”

“We believe that we have rationalized the nomenclature of the figs in the southern half of Africa,” adds Burrows. “We describe one new fig (Ficus natalensis subsp. graniticola), we shed light on the appallingly difficult Ficus thonningii complex, and we’re offering the public a relatively easily understood overview of the figs and other members of the family Moraceae.”

The book is also a splendid example of botanical art. Complementing John Burrows’s superb photographs, the pen-and-ink illustrations by Sandra Burrows were all drawn from live specimens during the field trips. This, she explains, “is

the best way to capture the ‘jizz’ of a plant. But it’s very challenging. I often have to contend with mosquitoes and flies buzzing around. Sometimes I resort to sitting in the back of the vehicle, or we pitch tent so I can crawl in and escape the insects.” After a trip, she used the herbarium species that they had collected, their photographs, and her field drawings to finish the final illustrations, and often had to wait for another trip to see the fruits to complete the plate. In the wild, it is practical to work in pen and ink. She explains: “It makes sense to illustrate in pen, as sometimes I have to do field drawings of three or four species after we’ve pitched camp in the evening when the long day’s drive is over. So there’s no time to fiddle with colour. Besides, the black and white illustrations complement the full-colour photographs.”

Together, these pictures present a uniquely beautiful visual record of the figs of this region.

A tribute to the fact that for John and Sandra Burrows botany is not just an interest but a way of life, this volume is a must for professional botanists and for anyone interested in the plants of Africa. ■ For details visit www.succlents.net

Atlas and Red Data Book of the frogs of South Africa, Lesotho and Swaziland. Edited by L.R. Minter, M. Burger, J.A. Harrison, H.H. Braack, P.J. Bishop, and D. Kloepfer (Washington D.C.: Smithsonian Institution, SI/MAB Series #9, 2004).

The culmination of a nine-year project, this book serves the specialist and the serious amateur naturalist. It maps the distributions of all known species of frogs in this region and assesses their conservation status. About 400 people contributed 42 500 records – a fine achievement, given that frogs are best heard and observed at night and in the rain.

Of the 115 species of frogs in the area, 20 (17%) are classified Threatened. A further five species are Near Threatened, and the status of another eight is Data Deficient, as so little is known about their occurrence and life histories. The status of some is remarkably fragile. The critically endangered Table Mountain ghost frog is found in just four streams on Table Mountain, for instance, and the only remaining population of the (also critically endangered) micro frog on the Cape Flats is in the indigenous vegetation inside Kenilworth Racetrack. Mainly in danger from afforestation (which dries up streams, seeps, and wetlands and destroys indigenous vegetation), agriculture, urban development, and road building, amphibians need to be part of conservation planning, say the editors, because frogs “are a critical part of the food web, both as predators and as prey, and serve as sensitive indicators of environmental health.”

To order, contact the Avian Demography Unit at the University of Cape Town. Tel. (021) 650 2423 (Sue Kuyper) or e-mail James Harrison at batlas@adu.uct.ac.za

The end of the line: how over-fishing is changing the world and what we eat. By Charles Clover (London: Ebury Press, 2004).

World fishing industries are raping the planet’s stocks, because people want more fish, modern gadgets allow huge fishing vessels to find and kill fish more efficiently than ever, political will is weak against efforts to maintain marine stocks, and because of appalling waste, writes Charles Clover. Having raided their own supplies, rich countries (whose taxpayers often subsidize the fishing) buy up fishing rights cheaply from African countries and continue over-fishing there. The collateral damage of “by-catch” (or fish with no commercial value that’s killed and thrown back into the sea) continues unhindered, as does devastation of seabeds and entire ecosystems of corals, algae, and crustaceans by trawlers and dredgers. Clover advocates stricter management, quotas, and policing with the help of satellites and the Internet. This book needs to be taken seriously.

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Letters Q

Letters to Conservation is no picnic ongratulations on the first issue of QUEST. I look forward to more, equally interesting reading in future.Viewpoint (“The plague of environmental absolutism”) makes the point that good intentions, wrongly applied, can do more harm than good. I fully support this view. The world is filled with examples of misguided attempts, arising from uninformed and extremist views, to deal with modern problems. One needs, however, to beware of the ‘absolutism’ label. Here is another view on examples that referred to invasive alien plants.

The Viewpoint article speaks of an arbitrary line drawn at 350 years ago to define ‘alien’ plants, adding that “fynbos was in its own time an alien invader.” Let us ignore for a moment that alien plants are normally defined by species, and that fynbos is a vegetation type comprising thousands of species: let us rather define ‘invasive alien’.

Alien species are species that arrive from outside their natural distribution range (normally with the aid of humans). They do not include species that spread gradually to new areas. Some fynbos species may fall into the ‘alien’ category, but most evolved in situ over tens of millions of years. They should not be lumped together with alien plants imported by European settlers in the past 100 to 200 years. The difference is that species evolving in situ have hosts of co-evolved insects and pathogens to keep them in check. Some (not all) alien species, when finding themselves on new shores, unhindered by co-evolved pests that keep them under control, exhibit what is known as ‘ecological release’, that is, these few alien species can run riot over the landscape, causing significant ecological damage. To treat them in the same way as we treat fynbos would be foolish.

C

I agree with Viewpoint that many alien plants and animals are useful – they meet almost all our food and fibre needs. But the article uses the example of felling shade trees at the Silvermine lakeside as illustrating the wrong thing to do, saying that “they were not an invasive threat.” These trees were cluster pines (Pinus pinaster), one of the most aggressive invaders of fynbos ecosystems: as such they certainly were a threat. They provided shade for picnickers and hikers on hot days, but in cases like this society must make choices, and such choices need to be informed by an understanding of the consequences of choosing a particular course of action – in this case to fell or not to fell the trees.

Leaving the cluster pines in place would have ensured ongoing shade, but these trees would over time have spread beyond the borders of the plantation – that’s what invasive species do – with severe impacts on the biodiversity of the Table Mountain National Park, a proclaimed World Heritage Site that South Africans have an international obligation to protect. The trees would have increased the intensity of inevitable fires, with serious consequences for human safety and for soil stability in the water catchment areas.

They would have used excessive amounts of water, not all of which “simply runs into stormwater drains” (there are several minor but important reservoirs on Table Mountain, including the Silvermine “lake” itself).

Society needs to weigh up such pros and cons and take appropriate action (based on the best scientific evidence available) that will minimise costs and maximise benefits. To view this approach as ‘destructive absolutism’ is wrong.

Brian van Wilgen, Stellenbosch

I

One known effect of climate change is the increased risk of invasion by alien species. Paradoxically, it has been shown in many natural environments that adding alien species leads not to gain, but to loss, of biodiversity. Such loss should be avoided as much as possible to keep our world properly functioning, especially in formally protected areas. I differ, therefore, from George Ellis, who regrets the removal of “shade-giving” trees within the Table Mountain National Park, and appears to favour the historical introduction of invasive woody species to the Cape Flats. He opines that we do not “need fynbos everywhere”, but we know that the indigenous vegetation of the Cape Flats (including fynbos and ‘strandveld’) was and – what little remains after the spread of alien acacias from Australia – is, very different in species composition from the Cape Peninsula’s mountain fynbos: all need protection.

In trying to save Earth’s biodiversity, we environmentalists believe we’re helping to preserve our world for our children. We take our cue from researchers who study alien species and their effects. If George Ellis did the same, he might appreciate that combating alien species in natural environments in a changing climate is more important than providing shade to privileged picnickers. Like me, he could then invest in a hat!

John Cooper, Avian Demography Unit, University of Cape Town

address George Ellis’s article (“The plague of environmental absolutism”) as an environmentalist, despite my 40-year career as a scientist.

Many of my colleagues in the biological sciences, worldwide, have been moving from a strict study of living things to working towards their protection. In South Africa, as elsewhere, environmentalists look to biologists for guidance on managing the environment and for information about maintaining biological diversity on a planet at serious risk from the effects of anthropogenic climate change.

I cannot accept that most of my colleagues are “engulfed in an absolutism that restricts, and often destroys” or that they engage in “personal and political attacks”. Even in such direct-action NGOs as Greenpeace International I have met nobody who fits this description. Certainly I have encountered passion and strongly held views, but also willingness to argue and to listen to counterarguments.

Address your letters to The Editor and fax them to (011) 673 3683 or e-mail them to editor.quest@iafrica.com (Please keep letters as short as possible. We reserve the right to edit for length and clarity.)

44 Quest 1(2) 2 0 0 4

Q News

Q Q UEST crossword You’ll find many of the answers in our pages, so it will help to read the magazine before you do the puzzle.

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Centres of scientific excellence The South African National Research and Development Strategy encourages the creation of “centres and networks of excellence” in all branches of science and technology. They are to improve quality and regenerate the country’s science system. Interdisciplinary and cross-institutional research teams are intended to stimulate and sustain distinction, and, simultaneously, grow a new generation of highly qualified researchers. Specifically, they would achieve the growth of South Africa’s research base, the leverage of existing resources through networking, the inspiration of existing scientific capacity, and the attraction and development of new capacity.

Putting policy into practice, and as sponsor of the new centres of excellence (CoE), the Department of Science and Technology (DST) appointed the National Research Foundation (NRF) as the programme’s managing agent.

Located at the pinnacle of the NRF’s focus areas programme framework, the CoE programme is designed to raise the research and capacity development ceiling of existing top scientists to enable them to achieve the aims of the initiative.

New knowledge & HR capacity

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CoE 19

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Mission-driven funds

5-year grants Rated scientists & teams

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1- & 2-year grants Un-rated scientists 25

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NRF Focus Areas Programme JEMIMA

Across

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1 When this is removed from a woody species, the plant dies (4) 4 Descriptive of plants having medicinal (or culinary) properties; used by traditional healers (6) 7 A bluish friable rock of volcanic origin (10) 9 One side of a many-sided cut gem (5) 10 Museum at the Johannesburg Zoo (8) 11 A technique, for field use in developing countries, used for filling cavities (3) 13 One of the great apes (7) 16 Class of animal that feeds on flesh or other animal matter (9) 17 See 19 19/17 The bark of this tree has been used for centuries for the manufacture of cloth and clothing (5,3) 21 An insect in the stage between egg and pupa (5) 22 Bacteria in the mouth break food down into these corrosive substances, which cause dental decay (5) 23 One of the large felines housed in the Johannesburg Zoo in 1904 (4) 25 The arrangement of data, etc., for a computer (6) 26 The new --- house, without bars; opened on 24 September 2004 (3) 27 The ---- of Africa; the world’s biggest diamond (4)

2 A verb that means ‘to toughen by a process of gradually heating and cooling’ (6) 3 A collection of Internet sites that offer various resources through the hypertext transfer protocol (3) 4 Class of animal that feeds chiefly on grass and other plants (9) 5 A collective word for the animal and plant life of a region (5) 6 Unwelcome rodent on Marion Island (5) 8 High, upstanding diamond (9) 12 Measure for precious stones (5) 14 A disease of pines caused by a fungus (8) 15 A defensive or protective ditch usually filled with water (4) 16 The seed-producing fruit of a pine tree (4) 18 A disease in the form of an oblong sunken area of dead tissue which forms on a branch or stem (6) 20 When being rehabilitated, this ape is kept in a sanctuary rather than being introduced back into the wild (5) 21 An interconnecting circuit between two or more locations for the purpose of transmitting and receiving data (4) 24 One of the most dangerous predators to be found on oceanic islands (3)

Did you like this crossword?

Was it too difficult? Too easy? Just right? Fax The Editor at (011) 673 3683 or e-mail your comments to editor.quest@iafrica.com and let us know. (Mark your message CROSSWORD COMMENT.)

Centres of excellence in relation to the National Research Foundation’s focus areas programme.

The CoEs are, by definition, physical or virtual research centres. They concentrate existing capacity and resources so that researchers can collaborate across disciplines on long-term projects that are locally relevant and internationally competitive, and thereby increase research excellence and develop new capacity.

What makes this model different from other forms of financial research support are the long funding term of 10 years and the gathering together of existing talent across disciplinary and institutional boundaries. The vision of the CoE programme is to grow the number of centres over time and to increase the funding base to include more government departments.

The funding of each centre intends to • Exploit the competitive advantage vested in outstanding researchers • Reward, retain, sustain, and improve scientific excellence • Integrate smaller and related research initiatives into one programme • Achieve economies of scale by sharing personnel, equipment, data, and ideas • Provide secure and stable funding for research and the dissemination of scientific knowledge • Support planned, strategic, long-term research • Reduce the micro-management of academics and their resources by the funding agency.

The NRF received 70 proposals and, on 29 June 2004, the minister of science and technology, Mosibudi Mangena, launched the six DST centres of excellence that had been selected for support (contact persons and host institutions are given in brackets): • DST–NRF Centre of Excellence for Invasion Biology (Steven Chown, Stellenbosch University) • DST–NRF Centre of Excellence in Strong Materials (Darrell Comins, University of the Witwatersrand) • DST–NRF Centre of Excellence: Birds as Keys to Biodiversity Conservation at the Percy FitzPatrick Institute (Morné du Plessis, University of Cape Town) • DST–NRF Centre of Excellence in Catalysis (Jack Fletcher, University of Cape Town) • DST–NRF Centre for Excellence for Biomedical TB Research (Paul van Helden, University of Stellenbosch and Valerie Mizrahi, University of the Witwatersrand) • DST–NRF Centre of Excellence in Tree Health Biotechnology at FABI (Mike Wingfield, University of Pretoria).

– Robin Drennan, National Research Foundation For information consult the contact persons and visit the NRF web site at www.nrf.ac.za For more about the work done in the DST Centre of Excellence in Tree Health Biotechnology at FABI see pp.3–7 in this issue; for research in the field of invasive biology see pp.22–27.

Quest 1(2) 2 0 0 4 45

News Q New chips for old

Laser lights up layers The selective plane illumination microscope, developed at the European Molecular Biology Laboratory in Heidelberg, Germany, helps biologists to study tissues and small organisms. They no longer need to slice a sample into thin layers to study its internal details. Instead, this instrument illuminates an intact specimen with laser light, one thin (2–8 micrometres) layer at a time.

A lens and camera system takes images, layer after layer, building up a high-resolution picture.

Biologists can more easily study how embryos and other living tissue develop and differentiate, as the tissue samples stay alive for longer.

“Because it only illuminates the single plane we are looking at, the rest of

the sample is not suffering from the light,” says Ernst Stelzer, leader of the group that developed the microscope.

“This makes a dramatic difference in terms of lifetime.” His group has already produced images of fruit-fly embryos over 16 hours. So far, specimens have been genetically modified to produce green fluorescent protein, which ‘lights up’ under the laser. Instead of trying to get labelling dyes into organisms, the organisms themselves express the fluorescent protein when they are illuminated.

The microscope has better resolution than other living-sample techniques. Its design is so simple, says Seltzer, that other laboratories could build their own.

The California-based Advanced Micro Devices (AMD), rival to Intel and IBM, has been developing a manufacturing process to put more transistors on a single computer chip or to make existing chips smaller. This 90-nanometre process is technically challenging because some components are no more than five to seven molecules thick. Each chip now has almost half a billion transistors. The process doubles the number of chips that can be made from a single silicon wafer, and can lower costs, increase performance, and reduce heat.

The 64-bit chip is mainly for laptop computers. AMD is also including an antivirus and worm feature called Enhanced Virus Protection, activated by Microsoft Windows XP.

Reported from Science in the New York Times, 17 August 2004.

Reported in the New York Times, 17 August 2004.

Diary of events Q Iziko-SA Museum

The Transvaal Museum

(25 Queen Victoria Street, Gardens, Cape Town)

(Paul Kruger Street [opposite the city hall], Pretoria)

The SharkWorld exhibition takes the visitor on an evolutionary journey, 400 million years back in time, to the earliest predecessors of the shark and its fellow Chondrichthyians – skates, rays, and chimeras. You will see colourful artistic impressions of how the long-gone creatures may have looked, life-size marine models, an anatomy display of the innards of sharks, and “shark electric”, which explores the extrasensory abilities of sharks and their sensitivity to magnetic fields.

Other exhibits display the amazing diversity of sharks and rays, from tiny pygmy sharks with ‘light-up spots’ to the massive whale shark, and from the seemingly prehistoric sawshark to the electrifying torpedo ray.

Sponsored by the Save Our Seas Foundation and Iziko Museums, SharkWorld was designed and implemented by the SWH Design Partnership. Eminent shark authority, Dr Len Compagno of Iziko Museums, who also heads Cape Town’s Shark Research Centre, directs the project, which includes audio-visual programmes on sharks and conservation.

The Wonderful Things exhibition displays remarkable objects that have been taken out of the darkness of dusty cabinets for the public to see.

Included are the skull of Mrs Ples, fossils from Sterkfontein and the Cradle of Humankind, a quagga skull recently discovered in the museum’s collections, the “Big 12” (featuring extraordinary insects), and moths and butterflies in brilliant colours.

If you miss the special exhibition, visit the permanent displays in the museum – mammals, birds, reptiles, amphibians, fish (including an actual coelacanth), and a piece of moon rock. You can also see Mars rock that was brought to earth in a meteorite.

This is one of only 12 rocks known to contain Martian rocks that have fallen to Earth, and one of the few examples on display in any museum in the world.

The Transvaal Museum also has a Discovery Centre. It attracts visits from schools and offers, in all the South African languages, programmes and guided tours adapted to comply with the latest curriculum requirements (book for group visits and tours). Life-size replicas of the Mrs Ples skull (the world’s most complete skull of Australopithecus

Starts 29 October 2004. Tel.: (021) 481 3800.

46 Quest 1(2) 2 0 0 4

africanus from Sterkfontein, 2.1 million years old) are obtainable, subject to availability, from the museum’s bookshop.

Open every day (08:00–16:00). Tel. (012) 322 7632; fax. (012) 322 7939. For information e-mail Saskia Kempff at kempff@nfi.co.za or visit www.nfi.co.za (under TM, Transvaal Museum).

Still on ■ MTN ScienCentre travelling exhibition, Great South African Inventions For bookings and information, tel. (021) 529 8100; visit www.mtnsciencentre.org.za

■ Johannesburg Zoo education programmes and tours, all year round, with special activities during school holidays (see also p.19) Tel. (011) 646 2000, fax (011) 486 0244, or visit www.jhbzoo.org.za

Diary of Events welcomes news of science and technology events or happenings. Send full details under the heading QUEST DIARY to The Editor, tel./fax: (011) 673 3683 or e-mail: editor2.quest@discoverymail.co.za

Q ASSAf News African science academies: an opportunity for growth A big issue for the African Renaissance is the extent to which science and technology can become an important engine of development for Africa’s 54 countries. A large proportion of high-level scientists and engineers born and trained here has left the continent for more rewarding work environments that promote their talents. Fortunately, many have remained in, or returned to their countries of origin, committed to identifying and training bright young minds, and to establishing science systems that can keep the high-flyers at home to become part of the infrastructure for national development.

Developed countries recognize the need for national science academies to provide what government departments, national professional associations, higher education institutions, and museums cannot easily do: mobilize multidisciplinary teams to examine scientific issues at the highest level (at arm’s length from the government of the day), and advise on how best to help or protect the nation.

Science academies were originally ‘clubs’ of successful scientists, conferring personal honour and providing opportunities to engage fruitfully with each other. These have subtly evolved into very different institutions, where the high honour of membership or fellowship combines with the analysis of urgent issues for society, and where scientific knowledge (especially evidence-based analysis) can be used to identify feasible and optimal solutions to problems that affect the lives of citizens, rather than being focused on the personal intellectual satisfaction of the participating

scientists.

Since only eight countries in Africa have national science academies that can potentially work in this way, there is a long road ahead before the governments of the continent can make pervasive use of this excellent and efficient method of obtaining scientific advice. The African Academy of Sciences, headquartered in Nairobi, however, is a kind of ‘continental academy’, and the Network of African Science Academies (NASAC) has recently been established to assist existing academies to work together and to stimulate the creation of new national science academies in other countries.

A further initiative offers Africa a golden opportunity to mobilize its indigenous scientific forces (and probably its extensive diaspora of scientists) for local solutions to many scientific problems. The president of the National Academy of Sciences (NAS) of the USA, Dr Bruce Alberts, has actively promoted the ‘academy role’ in international science, particularly in developing countries. The National Academies (comprising the NAS, the US National Academy of Engineering, and the Institute of Medicine) has been awarded a grant of US$20 million over 10 years by the Bill and Melinda Gates Foundation to strengthen African science academies, particularly in their advice-giving role, with a broad focus on health issues.

Three African science academies will be selected by the project’s board (one of whose members is Dr Mamphela Ramphele of the World Bank) and given resources to hire staff, buy equipment, expand their ability to hold workshops

and conferences (often jointly with the other African science academies), and conduct studies of key issues affecting national development.

In August 2004, the Academy of Science of South Africa (ASSAf) hosted a fivemember delegation comprising Dr Ramphele and two other members of the board, Dr Michael Clegg and Dr Narciso Matos; the director of the board, Dr Patrick Kelley; and a senior programme officer of the National Academies, Dr Barney Cohen. For three days, accompanied by the ASSAf president and general secretary, they visited government departments, science councils, and other organizations. Key contributions to a possible role for ASSAf in the Gatesfunded project came from Academy members and the various South African hosts of these visits. The idea of a key role in science advice for a much strengthened ASSAf was widely supported, and seen as pivotal to the entire project.

The initial set of three partner academies will be selected in a few months’ time, followed by intensive activity fuelled by the funds for the project. Should ASSAf be among the ‘lucky three’, it will be dramatically empowered and will never look back.

This is an opportunity to put in place a key mechanism for science- and technology-driven continental development, and South Africa will benefit generally from an expanded functioning of its national science academy.

Wieland Gevers President Academy of Science of South Africa

Q News Francis Crick: revolutionary In February 1953, in the Eagle pub in Cambridge, England, Crick announced that that he and James Watson had “found the secret of life” that morning – the double-helix structure of DNA. Their discovery of what underlies biological replication and the biochemistry on which genes depend, revolutionized genetics, and gave birth to the disciplines that embrace biotechnology.

Until his death (on 28 July 2004), Crick continued his groundbreaking investigations – into the way DNA works as a blueprint for life, and, much later, into the workings of the brain.

With Watson and Maurice Wilkins, he won the Nobel Prize in physiology or medicine in 1962.

Awed by what they had found, he said in his

Nobel lecture: “It is one of the striking generalizations of biochemistry – which, surprisingly, is seldom mentioned in textbooks – that the 20 amino acids and four bases are, with minor exceptions, the same throughout Nature.”

Born to a shoe factory owner and his wife, Crick initially read physics, then researched underwater mines for the British Admiralty during World War II. Thereafter he became interested in “the division between the living and the nonliving” and switched to the life sciences. With no biology and little organic chemistry or crystallography, he taught himself these subjects – then went on to transform the world of molecular biology forever.

Francis Crick (1916–2004) Photograph: Courtesy of Joshua Lederberg

Quest 1(2) 2 0 0 4 47

Back page science Q Keep up the gossip

π

“I still didn’t know much about anything so I could go into whatever I wanted,” Francis Crick said in 1997 in a lecture at Rutgers University in New Jersey.

“I used what I call the ‘Gossip Test’ to decide what I wanted to do,” he added. “The gossip test is simply that whatever you find yourself gossiping about is what you’re really interested in. I had found that my two main interests which I discussed the most were what today would be called molecular biology – what I referred to as the borderline between living and the nonliving – and the workings of the brain.”

Molecular biologist and Nobel laureate Francis Crick (1916–2004).

On 14 March 2003, 25-year-old Daniel Tammet set a new British and European record by reciting pi (π) to more than 22 514 decimal places.

Daniel, who suffered epileptic seizures during childhood, took a few weeks to learn the number – backwards as well as forwards. “It was actually rather easy,” he said. “The hardest part was sitting still for so long.”

Daniel went 15 decimal places beyond the previous record set by David Thomas in 1998. The world record of 42 195 decimal places was set in 1995 by Hiroyuki Goto from Tokyo. Other recordholders over the years include Andreas Lietzow who recited 1 088 decimal places while juggling three balls and was even able to recite 288 digits while juggling 5 balls. (Reported in The Spectator, London, 20 March 2004.)

For more visit www.pi-world-ranking-list.com

Statistics ■ “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.”

Aaron Levenstein (quoted in Nature Genetics).

■ “He uses statistics as a drunken man uses lamp posts – for support rather than for illumination.”

British poet, Andrew Lang (1844–1912).

■ “Say you were standing with one foot in the oven and one foot in an ice bucket. According to the percentage people, you should be perfectly comfortable.”

Baseball player, Bobby Bragan (1963).

■ “The death of one man is a tragedy. The death of millions is a statistic.”

Joseph Stalin’s comment to Winston Churchill, at Potsdam (1945).

■“Statistics are human beings with the tears wiped off.” Paul Brodeur.

■ “Do not put your faith in what statistics say until you have carefully considered what they do not say.” William W. Watt.

■ “Statistics can be made to prove anything – even the truth.” Anonymous.

One sense can affect another “Menthol... the active component of minty sweets, can modulate our perceptions of hot or cold. A menthol solution in warm water will feel hotter in the mouth than water at the same temperature. Conversely, a menthol solution in cold water will feel colder than water at the same temperature.” (Len Fisher in How to Dunk a Donut: The science of everyday life, London: Phoenix [2003], p.154.)

If cars were like computers Christopher Evans, as long ago as 1979, when Moore’s Law had scarcely begun, wrote: “Today’s car differs from those of the immediate postwar years on a number of counts...But suppose for a moment that the automobile industry had developed at the same rate as computers and over the same period: how much cheaper and more

efficient would the current models be?...Today you would be able to buy a Rolls-Royce for £1.35, it would do three million miles to the gallon, and it would deliver enough power to drive the Queen Elizabeth II. And if you were interested in miniaturization, you could place a dozen of them on a pinhead.” (Quoted by Richard Dawkins in A Devil’s Chaplain, London: Phoenix [2004], p.128)

Watching TV is bad for you ■ The average young child in the USA watches about 4 hours of television a day and each year sees tens of thousands of advertisements, often for high-fat, high-sugar, or high-salt snacks and foods; thousands of episodes of violence; and countless instances of alcohol use and inappropriate sexual activity. By the time American children finish high school, they have spent nearly twice as many hours in front of the television set as in the classroom.

■ One study of 2 500 children conducted at Children’s Hospital in Seattle and published in April in the journal Pediatrics found that the more TV watched by toddlers aged 1 to 3, the greater their risk of attention problems at age 7. For each hour watched a day, the risk of developing attention-deficit hyperactivity disorder increased by nearly 10 per cent. Children with this problem find it hard to concentrate, have difficulty organizing, and exhibit impulsive behaviour. (Jane Brody in the New York Times, 3 August 2004.)

Answers to Crossword (page 45) ACROSS: 1. Bark 4. Herbal 7. Kimberlite 9. Facet 10. Biofacts 11. ART 13. Gorilla 16. Carnivore 19/17. Natal fig 21. Larva 22. Acids 23. Lion 25. Format 26. Ape 27. Star DOWN: 2. Anneal 3. Web 4. Herbivore 5. Biota 6. Mouse 8. Excelsior 12. Carat 14. Diplodia 15. Moat 16. Cone 18. Canker 20. Chimp 21. Link 24. Cat

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Bankers: Standard Bank Northcliff Account Number: 200 5222 05 Branch code: 006305 Account name: Quest Magazine POST the completed Subscription Form together with your cheque or a legible copy of your cheque/deposit slip to: QUEST MAGAZINE, PO Box 5700, Weltevreden Park 1715, South Africa OR FAX the Subscription Form together with deposit slip to: QUEST SUBSCRIPTIONS (011) 673 3683.

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