25 November 2009
Aspects of Osteoporosis - Dr Simon Rawlinson
THE SILENT KILLER
This is the name given to Osteoporosis, by the medical profession, we were told by Dr. Simon Rawlinson at the latest meeting of Sherborne Science Café. In the USA alone 300000 cases are diagnosed each year of which more than 25% may die within one year.
The disease affects women more than men, and particularly those with disability, as exercise involving impact, is particularly important. Apparently, this helps people to retain bone density and keeps the skeleton from going brittle. In fact we were told that in some Old People’s Homes ‘arm wrestling ‘ is a regullar part of the routine !
An old boy of Foster’s School, Dr Rawlinson , who works in St Mary’s in London, has been researching in bone development for many years. His latest theory is that there are two types of bone cell in our bodies, not one. He has recognized that the osteocytes from the skull use a different set of genes than those from the limbs.
We also found out that humans grow a new skeleton gradually taking about 7 years for this each time. Some of the audience admitted to being on their 11th one right now!
28th October 2009
Lasers, light and liquid crystals - Prof Roy Sambles
Isaac Newton, Thomas Young and Albert Einstein were just three of the great scientists who were fascinated by light. Prof Roy Sambles, in a talk entitled Lasers, Light and Liquid Crystals, managed to convey with immense enthusiasm how light and colour raise many interesting questions. He described some of the properties of light: how it sometimes behaves like a wave and sometimes like a particle. In a series of demonstrations he showed some of its more mystifying behaviour including polarisation, diffraction, refraction and interference.
All of us who are fortunate enough to be able to see have two astonishing detectors for light. A large amount of input data to our brains comes through visual images. Sunlight is of course key to our existence. The way the eye detects light, and how the brain interprets the signals from the eye as colour were discussed and some fascinating optical illusions were demonstrated.
The impact of light technology, the science of photonics, is ever growing. Lasers as light sources and optical fibres as communication channels are commonplace. The ability of different molecules to polarise light under the influence of an electric field led to the development of liquid crystals. Liquid crystal displays as the interface with the human eye are everywhere, in mobile phones, lap-tops and flat screen televisions.
The audience was treated to a stimulating evening and was left realising how enjoyable asking questions can be.
23rd September 2009
WE WANT WATERWHEELS !
This was the message delivered to Sherborne Science Café at their September meeting. Geoff Ward, the custodian of the Castleton Wheel, gave an expert’s view of mechanics and uses of water wheels down the ages. The Romans were using them in Britain 2000 years ago, telling their womenfolk to ” Cease grinding at the mill …..”
So useful were they that by the 17th. Century there were up to 20000 of them in use. So many in fact that they were causing problems on the waterways. Their uses ranged from milling corn, to crushing ore, pumping, and driving machinery such as spinning looms. In fact The Industrial Revolution could not have started without them. Made of wood some of them were as much as 60 feet in diameter, and there were many beautiful designs, as at Belper in Derbyshire with its horseshoe mill. They could be horizontal, vertical, overshot, undershot or breastshot, as at Castleton. Newton and Borda even fell out over the maths behind the calculation of fluid resistance - and Sir Isaac was wrong !
Built from the stone from the old station, the pumping station at Castleton was built in 1869 and ran for 90 years using water from the ‘Oborne Stream‘ (R.Yeo) to pump clean water from an aquifer to the reservoir off Bristol Road. We now have a new wheel at Castleton thanks to Geoff and his team who replaced the old one 3 years ago. We were also told that these wonderful wheels may make a comeback as climate change beckons, although they may take the form of an Archimedes Screw. New volunteers are always welcome to help run the old technology however !
12th August 2009
Galileo 400 - Special Anniversary Meeting
Bob Mizon, from Wessex Astronomical Society, described what we have learnt about our Moon since 1609. He introduced some basic facts about the Moon: its size in relation to features on the Earth; how the phases of the moon and lunar eclipses are produced; and the fact that the Moon keeps roughly the same face towards the Earth at all times. He discussed the influence of the Moon on the axis of the Earth, which results in the precession of the axis. He also pointed out that over the last fifty years we have learnt a great deal more about our Moon as a result of lunar probes sent to map the Moon from space, and as a result of landing men on the Moon. He ended by describing the vital role played by the moon in the formation of life on Earth, and explained the tides and their effect on life in the sea and the emergence of life on land.
Percy Seymour, from Sherborne Science Café, pointed out that Galileo was the first to use a telescope to show that our Milky Way consisted of a very large number of stars. Two main problems face astronomers who want to study the structure of the Milky Way. The first is that our Sun is one of many millions of stars in the plane of the Milky Way Galaxy, so we are actually embedded in the system which we are trying to study and second, there are tiny dust grains in the plane of the Milky Way which act as an interstellar fog and blot out the most distant parts. In the twentieth century radio astronomy has played a crucial part in understanding our Galaxy, because radio waves are not affected by the interstellar dust grains.
Arthur Davis, from Crewkerne Astronomical Society, spoke about our Sun since Galileo. Galileo was one of the first astronomers to see sunspots on the surface of the Sun. Arthur described the position of the Sun in our Galaxy, and gave a brief overview of the large scale structure of the Sun, pointing out how it generated its energy and how this energy found its way to the surface. Arthur has photographed over a dozen solar eclipses, so this was a major part of his talk. He explained and illustrated the different types of eclipses: partial, annular and total, and described what we can discover about the extended corona of the Sun from observations made during eclipses. He also spoke about the sunspot cycle and how the distribution of sunspots over the surface of the Sun changed over a roughly eleven year period.
The evening ended with all three speakers answering questions from the audience.
22nd July 2009
Darwin's place in history
Sherborne Science Café celebrated the 200th anniversary of the birth of Charles Darwin with an insightful lecture on the great man, given by Rob Lloyd, formerly Head of Science at Sherborne School. He described the background of ideas which were circulating in the scientific community of the time, leading up to the publication of Darwin’s famous treatise, On The Origin of Species in 1859. In fact Rob Lloyd suggested that although Darwin gets the credit for the idea of Natural Selection, many other scientific thinkers had already had this idea before him. The first of these was the Greek philosopher Anaximander in 540 B.C. We also learned that Darwin hesitated for many years over postulating his theory – perhaps fearful of the disapproval of religious orthodoxy. In fact he only published On The Origin … in 1859 because Alfred Russell Wallace was about to go into print with the same idea in advance of him.
However Mr Lloyd did concede that it was Darwin that had the most comprehensive body of evidence to support his theory. A lively debate ensued and the audience had an excellent evening. The consensus at the end was that Darwin was indeed one of the greatest ever scientists, even though one of his later theories, ‘Pangenesis’, was greeted with much scepticism by the scientific community. ‘Evolution by Natural Selection’ however is here to stay, as the evidence supporting it increases every day – and is overwhelming.
24th June 2009
Martin started by defining a fractal as a picture created by a simple set of rules. He showed us a number of examples of intriguing geometric shapes to illustrate his points. One was Sierpinski’s gasket; which consisted of a number of black and white equilateral triangles of increasing sizes – the smaller ones embedded within the larger ones.
In the second half of his talk he discussed some the algebraic principles which gave rise to the shapes shown in the first part of the talk. He also introduced complex numbers and vectors.
At the end of his talk he discussed some the applications of fractals to Brownian motion, the weather, data protection and the shapes of coastlines. There were a few questions from the floor.
27th May 2009
Vitamin D and sunshine
Dr Oliver Gillie advised his audience at the May meeting of Sherborne Science Café to throw away their sun-block, along with most of their clothes - for as long as they could bare it?! Explaining the benefits of Vitamin D, which is made in the skin with the aid of sunlight, he told us that too much skin protection was bad for our health.
He pointed out that a low levels of Vitamin D were not only linked with Ricketts, but also :- Osteoporosis, Bowel Cancer, Arthritis, Multiple Sclerosis, Diabetes and a weakened immune system. This would mean that the advice given by Cancer Research UK was wrong. In Western Europe, where light levels are relatively low, we need to get as much sun as we can. Only 5% of our daily needs comes from our diet. Therefore his motto was: ‘Let the sun shine in!’ – particularly in Northern England and Scotland.
His unconventional message was greeted with some skepticism by the large audience. However he pointed out that there was much research to support his claim, even in the BMJ. White skins had evolved from pigmented ones, in response to low light levels, when Man migrated out of Africa before the last Ice Age. It was in response to low light levels. A daily dose of 1000-2000 units of Vitamin D was therefore required by most people he advised.
25th March 2009
What does science tell us about complementary medicine?
The Sherborne Science Café held on the 25th of March saw a lively exploration of Complementary and Alternative Medicine led by Les Rose, a well-known contributor to the Journal of The Institute of Biology.
Les Rose first posed the question, ‘What is evidence?’ he proceeded to answer this by giving a hierarchy of answers, pointing out that evidence must be peer reviewed and also repeatable by others for it to have any value. He came to the conclusion that anecdotal evidence is no basis on which to market drugs in the NHS. This ‘medicine’ did not go down well with the supporters of CAM in the audience and a lively debate ensued. Les Rose used his diplomatic skills and humour to answer the questions raised.
However the speaker did concede that much more work was needed to be done on the placebo effect and that there is indeed a natural basis for many of our modern drugs. Other treatments such as acupuncture were also discussed and the conclusion was drawn that more controlled studies were needed.
The audience had much food for thought after this dose of scientific debate!
25 February 2009
A field guide to the isotopes
Prof Paul Stevenson
In an interesting talk on the nature and uses of isotopes, Professor Paul Stevenson started by clarifying the relationship between the atom and its nucleus. If the size of an atom were represented by the size of a cathedral, then the nucleus would be no larger than a fly within the cathedral. The nucleus consists of protons and neutrons, but the rest of the atom is made up of electrons orbitals around the nucleus. The number of protons determine the electric charge on the nucleus, which in turn determines the number of electrons in a neutral atom. It is the arrangement of the electrons in shells around the nucleus that determines the chemical properties, but the nuclear characteristics arise from the number of protons and neutrons.
The number of protons determines the element, but elements can exist in different forms called isotopes, depending on the number of neutrons. The physical laws governing the structure and behaviour of the nucleus are highly complex, and Prof Stevenson followed his introduction with a description of examples of some isotopes.
Hydrogen, the lightest element, has 1 proton, but can exist as three relatively common isotopes: hydrogen, deuterium and tritium, with 0, 1 or 2 neutrons respectively. Hydrogen and deuterium are stable, but tritium is unstable, and is radioactive. Water made with deuterium is called heavy water, and is used as a moderator in nuclear rectors to slow down neutrons in nuclear reactions. In most cases the chemical properties of an element are not influenced by the isotopic form. However, heavy water is biologically toxic, unlike ordinary water.
The isotopes of carbon were discussed, and the use of carbon-14 in radioactive dating of materials that had once been living. An excited state of carbon-12 allowed red giant stars to manufacture the heavier chemical elements, via a resonant state first proposed by the astronomer Fred Hoyle. The talk ended with a lively discussion with the audience.
28 January 2009
Finding our way through some of biology's moral mazes
Prof John Bryant
Sherborne Science Café was pleased to welcome Professor John Bryant of Exeter University to their first meeting of 2009. Prof Bryant is Professor Emeritus of Cell and Molecular Biology with a special interest in bioethics.
Modern medicine promises much – ‘miracle’ cures, freedom from genetic diseases, repair of damaged or worn-out tissues, infertility treatment – but also raises significant moral concerns. Prof Bryant challenged his large audience by first gently asking them to examine their own ethical choices in life: ‘Do you always keep to the speed limit?’; ‘What makes you keep to the limit if you do?’ Having got the audience thinking he then introduced genetic selection of embryos and the use of embryonic stem cells as topics for further discussion. He illustrated some basic genetic theory regarding DNA and inheritance. We learned that a white human female was closer genetically to a black female than to a white male. Our old friend the puny ‘Y’ chromosome was responsible for this. ‘It may even contain map reading genes,’ he joked.
After describing how the Human Genome Project had led to an understanding of the genetic basis of disease he then discussed the dilemma surrounding the selection of embryos for stem cell research. ‘What are the limits to our use of technology in trying to cure the sick?’ he asked. The work of the Human Fertilisation and Embryology Authority in licensing and monitoring IVF and embryonic research was also mentioned. By the end of the evening the audience was aware of the complexity of the issues and had begun to realise that there are few universally agreed answers to the questions raised. Most moral issues have to be rationalised by the individual rather than The State. Legislation of whatever kind will never please all of the people.