27 November 2013
Dr Alan Watson
The Science of the Singing Voice
Dr. Alan Watson, Reader at the Cardiff School of Biosciences and teacher at the Royal Welsh College of Music and Drama, opened his lecture by comparing the respiratory tract with a brass instrument where the lungs were similar to the tube in providing power, the larynx creating vibration and the tongue and lips controlling tone. He then described in detail the anatomy of the larynx noting that the cartilaginous structure was attached to the hyoid bone allowing it to move up and down. The ‘adam’s apple’ is larger in men because of the effect of testosterone; historically female opera singers needed a couple of days off once a month due to their monthly hormonal cycle.
The vocal cords have muscular, fibrous and cellular layers; the function of the three elements was illustrated by a video-stroboscope which showed the ripple effect of the opening and closing of the vocal cords when singing different notes.
The human voice has complex frequencies components which were explained in terms of the harmonics of a vibrating string; in general the higher the pitch the more dominant the higher frequency components. A sonograph of a mezzo-soprano singing Cwm Rhondda was shown to demonstrate the changing frequency components during the performance of the song.
Resonances in the cavity of the mouth, typically in the region of 2000 - 3000 Hertz, allow a trained singer to greatly amplify the voice and to compete with a full orchestra. However, at very high frequencies it is not possible to both amplify the sound and perform the complex movements required to articulate speech. This explains why it is difficult to understand what an operatic soprano is singing!
The variations of vowel sounds heard in the different regions of the UK are largely achieved by tongue movements, and examples of the frequency components were shown.
After a lively question and answer session the meeting was closed by the Chairman, who after presenting the speaker with a bottle of wine, asked whether there had been any research into the effect of excess alcohol on the singing voice, a question greeted with much hilarity and applause.
23 October 2013
Niels Bohr - the man, his work and his influence
Percy Seymour started by sketching the background to Niels Bohr’s work on the atom. He point out that the idea of the atom started with the Greek philosopher Democritus, but an essential tool for Bohr’s work was the idea of a Sun-centred universe, which was initiated by Aristarchus of Samos. John Dalton, the Manchester chemist, gave us a new the version of atomic theory and used it as the basis for chemistry, leading to our understanding of how chemical elements could combine to form compounds. As the concepts of our solar system behaving according to the Newtonian laws of motion and gravity were important to Bohr, Percy then briefly discussed these ideas. The essential background to modern atomic theory really started with JJ Thomson's discovery of the electron and Max Planck's theory that light consisted of tiny particles carrying specific amounts of energy which he called quanta.
Rutherford’s work started with an attempt to investigate the structure of atoms by bombarding gold foil with alpha particles. This was at Manchester University. Niels Bohr came fromDenmark on a scholarship from the Carlsberg Organisation. Initially he came to study at the University of Cambridge, but eventually he moved to Manchester to work with Rutherford. He realised that according to the physics of the day, Rutherford's idea could not work. This was because the electrons would spiral into the central nucleus as they radiated energy in their motion around in circles. To explain this Bohr introduced the concept that electrons moved around the central nucleus in very precisely define orbits, at exact distances from the nucleus, and an electron would only radiated energy when it moved from an orbit further from the nucleus to one closer to the nucleus; this was the beginnings of the quantum theory of the atom.
In 1913 Bohr wrote three papers clarifying his ideas. The first paper explained how different atoms would emit different spectral lines when they were heated, and they would absorb certain lines when white light was passed through a collection of these atoms. The second paper showed how electrons were built up around the central nucleus to make up the 92 known elements of the periodic table. In his third paper he explained how atoms of different chemical elements could combine to form chemical compounds. This was the first great step in helping us to understand the basic structure of all material substances. Percy went on to explain how Bohr used the Rutherford model of running a research centre to set up his own Niels Bohr Institute in Copenhagen.
After the interval Percy went on to discuss how Albert Einstein modified the work of Isaac Newton to give us a new theory of gravitation, which was based on the bending of space and time by massive objects like our Sun. Prof Arthur Eddington from Cambridge and Frank Dyson, who was then Astronomer Royal at Greenwich Observatory, organised two expeditions to test Einstein's theory by measuring the bending of light by the Sun during a total eclipse. The experiment showed that Einstein's theory of gravity was more accurate than Newton's work on gravity.
Percy ended by comparing the work of Niels Bohr and Albert Einstein and showed that Bohr’s work was as important to modern theoretical physics as that Einstein. The evening ended with several questions from the audience.
25 September 2013
The Great Crane Project
Damon Bridge, Project Manager of the Great Crane Project, described the initiative to reintroduce the Eurasian or Common crane to the Somerset Levels. Apart from a small colony in East Anglia, the crane has been extinct in Britain for over 400 years. Cranes were once plentiful and widespread, as indicated by the large number of placenames with a ‘crane’ connection, like Cranwell, Cranfield and Cranbourne. The crane is the tallest breeding bird in Britain, standing four feet tall with an eight foot wingspan. They are often confused with the heron, but they are more closely related to coots and moorhens. Unlike herons they cannot perch and need to roost on the ground or in water to avoid predators. They are social birds with a highly developed ‘pecking order’.
The Somerset Levels were chosen as a suitable habitat because of the large areas of open space, with wetland and hay meadows providing food. Eggs were donated from colonies in East Germanyand Poland and were hatched at the WWT centre in Slimbridge. Special techniques were used to rear the young birds to prevent them developing attachments to humans, a behaviour known as imprinting. Handlers wore grey overalls and used sticks modelled on an adult crane’s head to disguise themselves. Birds were ringed to enable individuals to be identified and tracked. In all 76 eggs have hatched and 66 birds have survived since 2009. Some birds are beginning to show the instinct to mate and it is hoped that several pairs will produce chicks next year. Cranes do migrate, but the behaviour is not instinctive – it is learnt from the parent birds. Thus the colony is likely to remain resident, but may travel and return over large distances.
The meeting ended with a wide-ranging session of questions
24 July 2013
An introduction to neuro-linguistic programming
Rick Beaver, Senior Educational Psychologist for Somerset County Council, gave us an introduction to neuro-linguistic programming (NLP) at our July meeting. He started by explaining that NLP was developed in the 1970s as a result of the work of Bandler and Grinder. It is a model of how an individual’s internal subjective experiences are communicated to other people. It is a model not the truth. The question is whether the model enables us to gain the outcomes we wish to achieve in understanding how communication works. Rick pointed out that there were various elements to our primary experience which depend on our main senses: verbal, auditory, kinesthetic, olfactory and gustatory. NLP seeks to understand how we communicate our model of the world to someone else via various forms of verbal and non-verbal communication.
When communicating our view of the world to someone else, we can make use of a variety of different types of images. The main types of images are visual and auditory, but we sometimes use gustatory and olfactory. Our eyes can convey some information about how we are thinking and which sense experience is dominant at the time.
Rick expanded on one particular approach used in NLP called the Swish Pattern, which has four steps:
First step. Have the client find a visual memory of the situation where they want to change the way they feel. Check it is an associative picture, it has a border, and that the negative feelings is produced by it.
Second step. Go through the submodality distinctions to find which submodality changes have a significant effect on the feeling.
Step three. Have the client create a second picture of how they would like to be in this situation. Check the picture is associated, it has a border, and the positive feeling is produced by it.
Step four. Go through the previously identified submodalities to find which have a significant effect on the feeding.
He went on to give an example of how he had successfully used this procedure with a young boy whose behaviour in the playground was very disruptive.
Rick expanded on other aspects of neuro-linguistic programming in response to the questions raised from the audience.
Report by Percy Seymour
26 June 2013
Prof Philip Howse
Visual illusions in art - butterflies and moths
Professor Philip Howse, formerly of Cardiff and Southampton Universities, gave us a fascinating insight into the images that butterflies present to potential predators. He pointed out that human eyes are different from those of other animals and therefore we may see things differently. Whereas humans have three types of cone receptors in the retina (red, blue, and green), other animals may have up to five. If only one cone is present, images are seen in monochrome, with as few as 100 shades of grey. However if, like many birds, four or even five cones are present, as in pigeons, then the number of hues detected is over 100,000,000, with vision extending into the ultra-violet. From this it follows that brimstone butterflies, which are yellow to our eyes, will look blue under UV. Butterflies and moths, which to us appear brown, may be seen as coloured by many birds.
Humans are also used to seeing objects the ‘right’ way up; the image of a butterfly is most familiar when shown with the wings open and the head uppermost. Birds see images orientated at various angles. This can cause the image portrayed to be very different. For example the markings of a Hawkmoth, when viewed upside-down, resemble a fox. And whereas predatory birds, like owls and hawks, have good binocular vision and depth perception, most birds have eyes on the side of the head to give a better all-round view. Thus they are less able to determine size and distance, and patterning becomes more important. The prominent ‘eye-spots’ on many butterflies have evolved to act as warning signs to birds. Professor Howse advanced the theory that red admiral butterflies show the markings of goldfinches on their underwings, and white admirals magpies – all warning symbols to potential predators.
Professor Howse used video to show us some examples in motion. One, of a 13 inch moth from South East Asia, showing an image of a snake apparently about to strike, was quite spectacular. He recognised that his theories were hard to justify statistically and that more evidence was needed. He was still hard at work on this in his retirement.
Report by Rob Bygraves
22 May 2013
Prof Michael Lockwood
Solar variability and climate change
Professor Michael Lockwood is the Director of Research at the Meteorology Department at Reading University and a Fellow of the Royal Society. He gave a wide ranging talk on Global Warming and the possible causes. He talked about the history of measurements of the Sun’s output and variability from tree rings to space born instrumentation. He highlighted the evidence that since reasonably accurate measurements have been available (approximately 200 years), though cyclical, the average output of the sun has not changed significantly. What has changed is the amount of greenhouse gases in the upper atmosphere, particularly CO2. This again has a cyclical component, but the average has increased dramatically in the last 40 years and very recently has reached 400ppm. Other gases have also increased but to a lesser extent. CFC’s have recently stopped increasing following the Montreal Protocol but the hole in the Ozone Layer has not yet started to decrease.
The reasons for the CO2 increase were discussed but apart from volcanic activity, responsible for about 10%, they are all man-made. Professor Lockwood then went on to discuss the possible consequences, partially prompted by questions from the audience. He had no firm conclusions but a number of views from his position of being in the centre of climate research.
The main subjects commented on were:
There is no evidence the Gulf Stream will be choked off any time soon.
Winter ice at the poles is getting less on average.
Average sea water height is very difficult to measure but has not increased significantly to date, it will increase due to ice melt and expansion due to temperature increase, about 50% from each cause
El Nino affects the climate significantly but not Global Warming.
He does not believe the Earth is self healing, it could finish up like Venus, but given the political will, it is possible to reverse the generation of greenhouse gases. It may take a global catastrophe to kick start a recovery.
Surprisingly, there were no questions from the known Sceptics and the Professor received warm applause from the audience for a very well presented talk.
Report by Tony Allen
24 April 2013
Dr David Acheson
What's the problem with Maths?
Dr David Acheson, from Jesus College, Oxford, entertained us with mathematical puzzles and tricks at the April Science Cafe. Right from the start he used audience participation. He asked for volunteers, and after supplying them with pencils and paper, he gave them some simple mathematical tricks to do.
He then moved on to discuss the summation of different series of numbers. He then used the dividing up of a pizza to show that some series could have a finite sum, even if they had an infinite number of terms.
The summation of one series of numbers which he introduced had the number π as its final answer. Why should π, the ratio of the circumference of a circle to its diameter, have anything to do with the sum of an infinite series? This led him on to discuss his own experimental efforts to find the value of π, first with a round table and then with a gramophone record. He invited members of his audience to improve on his results for the gramophone record, during the interval.
He also discussed how a compound pendulum, place on a platform vibrating at just the right frequency and with an appropriate amplitude, would have vertical stability. This provided his explanation of the Indian rope trick!
He then went on to discuss his own views on how mathematics should be taught to children. This gave rise to a lively response and discussion from the audience. Although people did not agree with all that David said, the debate on the teaching of mathematics was lively and well balanced. It proved to be an instructive and entertaining evening.
report by Percy Seymour
27 March 2013
Dr Aviva Tolkovsky
New ideas about life and death in the brain
Sheborne Science Café was given a fascinating insight into the working of our ‘internal computer’ – the brain - at the March meeting. Dr Aviva Tolkovsky explained how nerve cells from the brain migrate in embryos to their target organs, up to 50% dying on the journey.
However these target organs attract and nurture the nerve cells (neurons) using Neurotrophic Growth Factors (NGF). The discovery of NGFs in 1986 has lead to research into the repair of nerve cells, especially those associated with the spinal cord. Some of the benefits of this are seen in the repair of some parts of the nerve cord which are now possible in those with spinal injuries.
We learned that all cells are programmed to die, in an orderly process known as apoptosis. This is much better for us than if they die randomly as this leads to inflammation affecting the whole body. Astonishingly, we lose 50-70 billion cells each day; although this sounds alarming we have several trillion anyway so can afford to lose a few! There is much research now into trying to apply the ‘apoptosis mechanism’ to unwanted cells such as those involved in cancers. This process is used in treating patients with chemotherapy and radiotherapy. Apoptosis might also be involved in neurodegenerative diseases like Alzheimer’s and Parkinson’s, but recent findings show this is rarely the case, and the process is more complicated. In Alzheimer’s disease amyloid plaques, or rogue proteins, invade the brain, particularly the hippocampus region. Dr Tolkovsky outlined some of her most recent research into studying these processes.
Report by Rob Bygraves
27 February 2013
The Joy of Specs
Simon gave us an overview of his work with people who suffered from severe eye defects in one area of Africa. He introduced his talk with the words: “…the highs and low of delivering eye care in the Kenyan outback.” He briefly discussed the setting up of the Akamba Aid Trust to support work in Akamba tribal region of Eastern Kenya. He described some of the problems of establishing case histories for people seeking eye treatment, and pointed out that it was easier to carry out objective eye tests.
Simon went on the explain some of the more common visual defects, such as myopia, presbyopia and astigmatism. He then went on to explain the basic properties of different types of lenses, and how they were used to correct eye defects. He outlined the spectrum of eye diseases found in Western countries and compared them with those commoner in his African patients. Whereas the commonest diseases in the UK are those of old age, such as glaucoma and AMD, in Africa cataract is much commoner, due to prolonged exposure to sunlight. Some of these differences were due to the fact that the life expectancy of the people in Kenya, which was early to mid-fifties, was much lower than that in Europe.
He then pointed out that certain disorders, such as cataract and glaucoma, could only be treated effectively using surgery. He showed a number of slides which illustrated, very graphically, some of the problems which he had encountered in his work. He then described the type of treatment centre which he would like to set up in this region. Members of the audience had brought unwanted spectacles which Simon reassured us would be put to good use.
There was a very lively discussion at the end.
Report by Percy Seymour
23 January 2013
Dr Tim Robinson
Food allergy & food intolerance
Dr Tim Robinson, a GP from Beaminster with an interest in nutritional medicine, spoke about food allergy and food intolerance. Adverse reactions to food are increasingly common; it is estimated that 25-30% of the UK population are affected. There has been a four-fold increase in food allergy in the last 20 years. Dr Robinson outlined the difference between allergy and intolerance, and described the diagnosis and treatment of the conditions.
Allergy is the response of the immune system to a foreign protein. Immunoglobulin (IgE) antibodies to the protein are produced which attach to mast cells, widely present in body tissues and fluids. At initial exposure the immune system is sensitised; a second exposure activates the process and the mast cells degranulate with the release of histamine. It is the release of histamine that leads to the symptoms of the allergic reaction: reddening or swelling of the skin; constriction of airways; dilation and increased permeability of blood vessels. Severe reactions (anaphylactic shock) can lead to respiratory distress and a drop in blood pressure with fainting or collapse. About 20% of severe allergic reactions are due to food. Various theories have been advanced to explain the recent increase in food allergy including: a more urbanised lifestyle; the ‘hygiene hypothesis’ (growing up without exposure to common infections); addition of harmful substances - antibiotics, passive smoking and house dust mite.
Initial diagnosis and identification of the cause of the allergy relies on the ‘skin prick’ test, where very small amounts of potential allergens are introduced into the epidermis and the response observed. Dr Robinson stressed the importance of a detailed patient history. The commonest causes of food allergy in children are milk and eggs (which children usually grow out of); in adults peanuts and seafood are the most common causes.
80% of adverse reaction to food are not due to allergy, but cover a wide range of food intolerance. One problem is that many of the symptoms are similar. One common cause is an enzyme deficiency, for example if the body is unable to split lactose into an absorbable form it passes into the gut leading to bloating (osmotic load), and microbial fermentation. Many foods naturally contain histamine, or other compounds that produce histamine when digested. Other substance in the diet causing reactions include tyramine (in cheese and wine), caffeine, salycilates and food additives (for example monosodium glutamate and tartrazine)
Milk demonstrates the difference between allergy and intolerance well. If an adverse reaction is due to the proteins in milk it is allergic; if the problem is an inability to break down lactose it is intolerance.
The talk was followed by a lively session of questions.