Annual Christmas Lecture: Machine Learning, Artificial Intelligence and the Future of Diagnostics in Healthcare Jason Cho

UpperSixth Talks

Terraforming Mars

Ivan Liu

Human activities are destroying the earth and there will soon come a point where saving the earth will become impossible. Terraforming Mars may provide humans with a way out if we ever need to abandon earth in search of a better home. Moreover, this far-fetched goal can also motivate us to innovate and create more which would benefit everyone in the process too.

I chose the microbiome as my topic after watching a video about the organisms that live within others. I became fascinated by the importance of balance between the microbes within the gut and the diseases that can result from an imbalance. One of these is known as Clostridium difficile, which is notoriously hard to treat. I heard about a novel treatment known as faecal microbiota transplant, which helps to restore the balance of microbes within the gut.

The Microbiome

Fleur Masters

Genetics of Asthma

Michelle Wong

Asthma is a major non-communicable disease, the inflammation and narrowing of the small airways in the lungs cause asthma symptoms, which can be any combination of cough, wheeze, shortness of breath, and chest tightness. In the UK, approximately 5.4 million people are receiving treatment for asthma, of which 4.5 million individuals are residents of England. Being such a common condition, the causes behind this disease have been fascinating as research on the genetics of asthma continues.

Modelling Infectious Disease

Isabelle Oliver

I chose to base my Moncrieff-Jones talk on a topic combining my two primary interests - mathematics and biology. Although initially seemingly the least related of all sciences, the applications of mathematics in biology are endless. I specifically chose to talk about mathematical modelling of infectious disease, one of the most interesting and typical examples of mathematical biology. Living through the COVID-19 pandemic, I wanted to deepen my understanding of how we model the spread of the SARS-CoV-2 virus and how this has been used to help combat the pandemic.

Special Relativity

William Pye

When I first heard that space and time were not fixed quantities, I couldn’t really believe it. I began to conduct more extensive research into the topic which uncovered even more real phenomena that seemed like pure science fiction. I decided to choose Special Relativity for my Moncreiff-Jones talk because of how incredibly interesting and accessible the content is. From observers ageing less to observers having different concepts of what the present is, Special Relativity truly challenges your intuition.

Terraforming Mars

Ivan Liu

THE PROBLEM WITH MARS

Mars is a red planet and one of our neighbouring planets and is the fourth planet from the sun. It is located around 1.5 astronomical units away from the Sun and is on the edge of the habitable zone which spans 0.9 to 1.5 astronomical units from the sun. The surface temperature on a summer day near the equator can reach up to 20 degrees Celsius while near the pole temperatures can get down to -125 degrees Celsius. The atmosphere on Mars is extremely thin at approximately 6 millibars at sea level compared to the 1013 millibars on earth. It consists of 95% carbon dioxide, 3% nitrogen, 1.6% argon and has a small trace of oxygen, carbon monoxide, water, methane, and other gases. Due to the low pressure on mars of around 0.006 atm and low temperature, water can only exist as a solid or gas. Mars does not have a global magnetic field, but rather a strong crustal field on its surface which creates local magnetic shields. When different local magnetic fields align, it creates a weak magnetosphere across the planet’s surface. The Mars Reconnaissance Orbiter (MRO), after years of collecting data, suggests that mars used to be a habitable planet like earth, which has a large body of liquid water. Riverbanks and dried-up deltas are common on the surface, they are created by the running water that is used to fill them. Furthermore, by determining the enrichment of water in the polar ice caps on Mars, scientists estimated that Mars used to have 7 times more water than the current volume of the permanent ice caps. The ocean would have covered mainly the northern hemisphere of the planet as it has relatively low elevations and would have covered around 19% of the planet’s surface. The young energetic sun around 3-5 billion years ago sent out powerful solar wind towards Mars which contain charged particles such as electrons and atomic nuclei such as carbon, nitrogen, oxygen, etc. These solar winds stripped away mars’ ancient atmosphere by ionizing gases in the atmosphere and releasing these highly energetic ions into space, combining the fact that the low-pressure sublimates liquid water which slowly left the Martian atmosphere over millions of years. In total, at least 20 million cubic kilometers of water had already left Mars during the wet Noachian period which ended around 3.7 billion years ago. If humans are ever to terraform mars, an artificial magnetosphere will need to be used in order to protect the artificial atmosphere from the solar wind. Moreover, with an artificial magnetosphere, gases released from volcanic activities are allowed to build up and increase the pressure and temperature which can trigger a positive feedback loop where the greenhouse gas is produced, increasing the surface temperature and hence releasing even more greenhouse gases.

ARTIFICIAL MAGNETIC SHIELD

Superconducting magnets

Superconducting magnets are chosen to perform such tasks as it can store a magnetic field indefinitely. This mode of operation is usually referred to persistent mode. At first a heating element is turned on to heat the switch wire until it is resistive. Then a burst of current is supplied by the switch wire to the conducting winding until a desired magnetic field is achieved. No energy is required to sustain the current flowing through the shorted

superconducting winding, so the heating elements are turned off and the power supply is switched off. At this point, the only energy required is the cooling contraption which keeps the winding in a superconducting state. Over a period, the superconducting magnet will still need to be charged again as the magnetic field will slowly decay due to small residual resistance in the superconducting.

(R is the residual resistance)

Surface magnetic shield

This proposal suggests a superconducting electromagnet that encircles Mars with a loop radius of around 3400km, a length of around 21000km, and a wire diameter of around 5cm. Because most high-temperature superconductors are constructed of rare elements, 109 kg of material is needed just to create the shield and 1015kg of material will have to be mined to obtain the rare elements. This is only around 0.1% of Olympus Mons’ mass (largest volcano in the solar system which is located on mars).

Orbital magnetic shield

A spacecraft can be placed at the L1 Lagrange point (The point the gravitational pull between the sun and Mars matches the centripetal force) so that it will always be the same distance from Mars. This spacecraft will also operate with superconducting magnets and the magnetic field will be increased until the magnetotail encompasses the entirety of mars. With this method the spacecraft can also orient itself to minimize the mass and momentum of solar winds, hence reducing energy flow into the craft.

INCREASING THE ATMOSPHERIC PRESSURE

Increasing the air pressure on mars can be achieved by deploying nuclear bombs on the poles of Mars to release the frozen CO2 into the atmosphere. The following calculations show the number of Tsar bombs (the world’s most powerful hydrogen bomb created, which has a theoretical yield of 100 megatons) that will be needed :

Heat enthalpy of sublimation of dry ice: 591 KJ/kg Density of dry ice at 194.5K 1atm: 1562 kg/m^3 Volume of dry ice on both poles: 3.2x10^15 m^3 Temperature of Mars polar caps: 120K Boiling point of dry ice: 194.5K Specific heat capacity of dry ice: 0.658kJ/kg K

The energy required to sublimate all the dry ice on both poles will be: (3.2x1015)(1562)(591)(1000) = 2.95x1024 J

The energy required to increase the temperature of the dry ice from 120K to 194.5K: (3.2x1015)(1562)(0.658)(194.5-120)(1000) = 2.45x1023 J Total energy: 2.95x1024 + 2.45x1023 = 3.20x1024 J

Numbers of Tsar bombs required: 3.195x1024/4.18x1017 = 7643605

With around 7600000 Tsar bombs the atmospheric pressure will increase by 6 millibars which is already for liquid water to exist and will be a good start in the long journey of terraforming mars.

The Microbiome

Fleur Masters

CLOSTRIDIUM DIFFICILE

Clostridium difficile (CD) is a rod-shaped bacterium, it was first discovered in 1935 by Hall and O’Toole in the faeces of healthy infants. It was not until 1978 that CD was found to be a cause of disease in the majority of antibiotic-induced diarrhoea cases. CD is more common in older patients with weaker immunity and most common in care homes as there is a higher chance of becoming infected. CD releases 2 toxins, A and B; Toxin A is an enterotoxin and toxin B is a cytotoxin responsible for CD’s virulence. A hypervirulent strain known as Ribotype 027 has increased massively in prevalence: in 1984-1993, it accounted for less than 0.1% of the samples, but by 2000-2003, it has already increased to around 50%. This is due to the increase in the toxin that this strain can produce.