A Question of Autumn

Why do leaves change colour in the autumn? It’s a simple question with a simple answer, you might say – they start to die. But there is a bit more to it than that, if you’re interested in the science, and how it can produce some of nature’s most picturesque scenery.

Every autumn the leaves from deciduous trees change colour before falling to the ground. This is due to the fact the leaves contain many chemical pigments, the most important being chlorophyll. Chlorophyll makes leaves green and helps in the process of photosynthesis, which attracts sunlight to the tree, helping them grow. Leaves also contain the chemical carotene, which has a yellow colouring. Carotene lives in the leaves all year, but is masked by the green of the chlorophyll.

The process of leaves turning from green to yellow, red or brown, is dependent on the climate. When autumn approaches and the warmer temperatures of summer begin to dip, the chlorophyll within the leaves begins to break down. Other pigments that live beneath the chlorophyll, such as the carotene, come forward.

Chlorophyll is dependent on water as well as sunshine. As the climate cools and the tree draws colder water up through its roots, the tree prepares for winter. It does this by growing a thin layer of cells over the water tubes in its leaves, closing them up in preparation. Without a regular supply of water, the green chlorophyll starts to disappear and the other colours in the leaf, such as the yellow carotene, can be seen. In some trees, when the leaf cells build, the water blocking wall which seals the tubes in the leaf’s stem traps sugar inside the leaf. This turns the sap and therefore the leaf red, or even purple.

The final part of the process before a leaf falls is when the water within the tree dries up completely. This dehydration kills any remaining green chlorophyll, as well as the yellow and red pigments. Consequently, the leaves turn brown and start to die, becoming dry and crunchy before they fall from the tree.

All in all, it’s quite a complicated and intricate process that provides us with this often beautiful time of year. When it isn’t raining at least!

Scientist and mathematician Galileo Galilei was born on February 15th, 1564, in Pisa, Italy. A pioneer of maths, physics and astronomy, Galileo’s career had long-lasting implications for the study of science.

In 1583, Galileo was first introduced to the Aristotelian view of the universe, which was a religion-based view of how the world worked. A strong Catholic, Galileo supported this view until 1604, when he developed theories on motion, falling objects, and the universal law of acceleration. He began to openly express his support of the controversial Copernican theory, which stated that the Earth and planets revolved around the sun, in direct contrast to the doctrine of Aristotle and the Church.

In July 1609, Galileo learned about a telescope which had been built by Dutch eyeglass makers. Soon he developed a telescope of his own, which he sold to Venetian merchants for spotting ships when at sea. Later that year, Galileo turned his telescope toward the heavens. In 1610 he wrote The Starry Messenger, where he revealed that the moon was not flat and smooth, but a sphere with mountains and craters. He discovered that Venus had phases like the moon, and that Jupiter had revolving moons, which didn’t go around the Earth at all.

With a mounting body of evidence that supported the Copernican theory, Galileo pushed his arguments against church beliefs further in 1613, when he published his observations of sunspots, which refuted the Aristotelian doctrine that the sun was perfect. That same year, Galileo wrote a letter to a student to explain how Copernican theory did not contradict Biblical passages, but that scripture was written from an earthly perspective, and that this implied that science provided a different, more accurate perspective.

In February 1616, a Church inquisition pronounced Galileo as heretical. He was ordered not to “hold, teach, or defend in any manner” the Copernican theory regarding the motion of the Earth. Galileo obeyed the order until 1623, when a friend, Cardinal Maffeo Barberini, was selected as Pope Urban VIII. He allowed Galileo to pursue his work on astronomy on condition it did not advocate Copernican theory.

In 1632, Galileo published the Dialogue Concerning the Two Chief World Systems, a discussion among three people: one supporting Copernicus’ heliocentric theory of the universe, one arguing against it, and one who was impartial. Though Galileo claimed Dialogues was neutral, the Church disagreed. Galileo was summoned to Rome to face another inquisition, which lasted from September 1632 to July 1633. During most of this time, Galileo wasn’t imprisoned, but, in a final attempt to break him, he was threatened with torture, and he finally admitted he had supported Copernican theory. Privately, though, he continued to say he was correct. This ultimately led to his conviction for heresy and as a result he spent his remaining years under house arrest.

Despite the fact he was forbidden to do so, Galileo still went on to write Two New Sciences, a summary of his life’s work on the science of motion and strength of materials. It was another work that has helped cement his place in history as the world’s most pioneering scientist, even if he was not fully appreciated in his own time. Galileo Galilei died on January 8th, 1642.

By far the biggest killers in today’s Britain are cancer and circulatory disease. Of the 501, 424 people who died in 2014, 29% died of cancer and 27% from heart attacks plus strokes. There is no doubt as to why charities seeking a cure for these scourges attract so much public support.

By contrast, leaving aside ‘flu and pneumonia, which mainly kill the already weakened elderly and infirm, infectious diseases account for a mere 0.6% of deaths. Your chances of being cut down by one of these in your prime of life is comparable with that of the threat from road traffic accidents or suicide. The reason we are dieing largely from heart disease and cancer is not because they are becoming more virulent, then. It is simply because we are living longer. Whereas in 1900 the average life expectancy in this country was just 48, now it is 81.

Antibiotics, the drugs used to treat bacterial infections, are a recent invention. Alexander Fleming stumbled upon them by accident in a London laboratory in 1928, though the first, penicillin, only went into mass-production in 1944. When it did so, it reduced at a stroke the number of deaths from infections, making hospital operations safe, battlefield wounds less fatal, and many serious diseases treatable.

Bacterial resistance to antibiotics emerged as a problem in the 1950s, but it has now become critical. Resistant bacteria have the ability to transfer their resistance to other species as well as passing it on to their offspring. So, once established, resistance to a particular antibiotic spreads rapidly, and bacteria with multiple resistances emerge. By 2004, bacteria resistant to almost all known antibiotics had appeared, while in 2015, bacteria resistant even to the”antibiotic of last resort” appeared in southern China. It is expected to spread to the west shortly.

In April 2014, the World Health Organization (WHO) sounded the alarm on this topic in no uncertain fashion. It spoke of a “major global threat” from such antibiotic-resistant bacteria, and an imminent return to a pre-antibiotic era, where people regularly die from the simplest of infections. If and when this happens, you would be far more likely to die from sepsis following a cut, or from airborne or waterborne bacterium, and less likely to live to an age when cancer and heart disease are a concern.

There is, though, a glimmer of light on this dark horizon. Traditional antibiotics are developed from defensive chemicals produced by fungi and bacteria. However, our own cells also produce chemicals that attack bacteria. They are short proteins (peptides) produced on our own cellular protein-assembly machines, called ribosomes. From this comes their acronym, RAMP antimicrobials (ribosomally synthesized antimicrobial peptides). These antimicrobials carry a positive electrical charge on their molecules and are attracted to the negatively charged outsides of bacterial cells. Once attached to the bacteria, they punch holes in the bacterial wall or membrane, killing the cell.

These natural defence molecules have been around for millions of years, during which time bacteria have failed to develop effective resistance to them. So, if this is the case, and if effective artificial mimics of natural RAMPs can be made, we may yet avoid a potential return to the dark ages of pre-antibiotics.

Bacteria, the discovery and action of antibiotics, and the emergence and spread of resistance, are all covered in depth in the new A level Biology course recently launched by Oxford Open Learning. You can find out more about the course here: http://www.oxfordhomeschooling.co.uk/subject/biology-a-level/

 

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The steamboat Turbinia can be seen at Newcastle’s Discovery museum

For anyone interested in taking a break from the books for a bit and taking a field trip to a Science Museum, or wishing to take part in an event on any part of the subject, the following may be of interest…

 

British Science Week 2015 will take place 13 – 22 March. This is a ten-day celebration of science, technology, and engineering and features, entertaining and engaging events across the UK for people of all ages. You can find more information, including activity packs for different age groups,  through their website at http://www.britishscienceassociation.org/british-science-week  . Anyone can organise an event or activity, and the British Science Association helps organisers plan by providing what are free support resources.

The Big Bang Fair UK: Young Scientists and Engineers Fair www.thebigbangfair.co.uk/
This fantastic event is coming back to the NEC this month from 11 – 14 March 2015. Visitors can meet engineers and scientists from large multinational corporations and a range of diverse and unique UK companies.

The Summer Science Exhibition at the Royal Society London
The Royal Society’s Summer Science Exhibition is their main public event of the year and showcases the most exciting cutting-edge science and technology research and provides a unique opportunity for the public to interact with scientists.
The Royal Society Summer Science Exhibition 2015 runs from 30 June – 5 July at the Royal Society, London.

There are a great many science museums in the UK. Here are some of the best.

1) Science Museum, Birmingham includes a science garden, planetarium and an interactive show which lets children explore the human body by seeing what it’s like to shrink to the size of a living cell. thinktank.ac/

2) National Space Centre, Leicester. Here you can explore the wonders of the Universe and discover the science behind the search for extra-terrestrial intelligence, plus take a tour of the 42m high rocket tower. There is also the Sir Patrick Moore Planetarium. spacecentre.co.uk

3) Museum of the History of Science, Oxford, has an unrivalled collection of early scientific instruments in the world’s oldest surviving museum building. mhs.ox.ac.uk

4) Museum of Science and Industry (MOSI), Manchester is currently showing a 3D printing exhibition. mosi.org.uk

5) The Science Museum, London contains a new nanotechnology exhibition, and the space travel exhibition is outstanding. I found the history of medical science exhibition very good. sciencemuseum.org.uk

6) Techniquest, Cardiff is currently showing an exhibition of colourful chemistry over the weekends 28 February – 22 March. techniquest.org

7) MAGNA, Rotherham has a fantastic electric arc furnace exhibition, including pyrotechnics. visitmagna.co.uk

8) Discovery Museum Newcastle www.twmuseums.org.uk/discovery.htm
This museum houses the finest collections of scientific material outside London and has important collections of maritime history.
The museum contains Charles Parsons’ ship, Turbinia, and Joseph Swan’s historic lightbulbs.
The Turbinia is my favourite museum exhibit which I saw on a school trip in 1967. She was designed by the Tyneside engineer Sir Charles Parsons in 1894 and was the world’s first ship to be powered by steam turbines. Until 1899, Turbinia was the fastest ship in the world, reaching speeds of up to 34.5 knots.

512px-thumbnailThere is currently a demand from various organisations for more pupils to be offered Triple Science in Secondary Schools. The Open Public Services Network, OPSN, has noted that the ‘curriculum taught in poorer parts of England is significantly different to that taught in wealthier areas.’ Geography and wealth have a significant determining factor on opportunity to study Triple Science. They also noted that ‘more than a third of schools do not enter any pupils for Triple Science.’

The CBI is calling for all children who achieve good grades in science at age 14 to be automatically enrolled onto Triple Science GCSEs. The CBI says that Triple Science gives pupils the confidence to go on and study A Level Sciences followed by science courses at University.

The Department for Education, meanwhile, says that ‘75% of Triple Science pupils achieving the highest grades progress to A Level Science subjects whereas 59% achieving these highest grades in Double Science progress to A Level Science subjects.’ They do not seem to analyse the reasons behind this. You wonder, is it simply confidence?

It is interesting to note that the Department for Education has recently removed the IGCSE Sciences from league tables, these being a greater equivalent to the old O Levels and more in depth.

So, what should we make of all this? The problems in poorer areas are invariably related to poor pupil and family attitudes, and so attempting to teach Triple Science to all in poorer areas has a certain futility to it until attitudes change.
One of the limiting factors in what is taught in schools is curriculum time. The legal requirement for science was 12%, but for pupils to have a fighting chance of doing well enough in science GCSEs they needed about 20%. My old school taught Double Science with 20% curriculum time. They started offering Triple Science to the top set with 24% curriculum time, the extra time coming from one lesson per week after school! They are now compelling all pupils to take Triple Science with 24% curriculum time built into the main timetable. Other subjects will have suffered as a result.

There is a notion that Triple Science is necessary for a good base to allow a pupil to go on and do A Level Sciences. I would say it is beneficial but it is by no means necessary. I took numerous pupils through A Level Chemistry with great success on the basis of doing Double Science alone long before any Triple Science was on offer in my school. This was also mostly before the modular system was introduced. If the Triple Science is so vital to promoting the uptake of A Levels why did students do A Levels on the basis of Double Science? And how did they manage? But they did if they were able enough.

It is not that Triple Science is vital for A Levels, but rather it is about pupils ability and suitability for A Levels. A Levels can be followed from any of Double, Triple and IGCSE Science. The courses chosen need to be on the basis of what is best for individual pupils in individual schools.
What is needless and unacceptable in my view is compelling all pupils to do Triple Sciences. Those who are not going on to A Level Sciences do not need 3 science GCSEs, with a quarter of their curriculum time being taken up in this way. This is not in their interests. The Double Science does a good enough job if we want the future general public to have a decent grounding in scientific knowledge. The other big issue with all pupils studying Triple Science is that it is not suitable to the ability of many pupils. We overestimate the ability of average pupils and we overestimate the long term memories of these pupils, so the extra material of Triple Science creates an unreasonable extra burden for no good result. Triple Science should be thought of as top sets subjects.
In conclusion the needs of the individual pupils are more important than the needs of the school, the education system, the league tables, industry and the latest political demands.

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Fox Talbot, with camera.

We have always learned a great deal from the use of texts, and of course from traditional word of mouth down the years. Where, however, would we be, without the picture? Or more specifically, the photograph? A drawing can tell us a lot, but a real image can provide us with even more – a real, genuine feel for the subject we are studying. For this reason, William Henry Fox Talbot, should be worth of a mention.

Fox Talbot was born on 11 February 1800 in Melbury, Dorset. He went to Cambridge University at the age of 17 in 1817, and in 1832 he was elected as an MP for Chippenham in Wiltshire, where he lived with his wife, Constance Mundy.

On a visit to Lake Como in Italy in 1833, Talbot was trying to draw the view before him, but his lack of success at capturing the beauty of the scenery prompted him to think about how he might create a machine that could capture the scene for him.

Once back at his home in Lacock in Wiltshire, Talbot began work on this project, using light-sensitive paper that he hoped would make sketches automatically.

Talbot was not the first inventor to have this idea. Thomas Wedgwood had already made photograms, which had successfully left lasting silhouettes of objects on paper, but these faded quickly. Then in 1839, Louis Daguerre invented the ‘daguerreotype.’ This was a system by which pictures could be captured onto silver plates.

Only three weeks after Daguerre revealed his invention, Fox Talbot reported his ‘art of photogenic drawing’ to the Royal Society. This process showed how to capture prints on thin pieces of paper that had been made light sensitive. This invention was to become the first step in the development of modern photography.

In 1841 Talbot went on to develop his photographic ideas further, when he invented the ‘calotype’ process. This involved discovering the three most essential elements required to develop pictures: developing, fixing, and printing photographs.

Talbot found that although exposing photographic paper to light produced an image, he believed it required extremely long exposure times to achieve success. Then, by accident, Talbot discovered that an image could actually be achieved after a very short exposure time, and could then be chemically fixed into a negative. This negative removed the light-sensitive nature of the print, and enabled the finished picture to be viewed in bright light.

With these new negative images, Fox Talbot could repeat the process of printing from the negative as many times as he liked. This was a major advance from the French daguerreotypes, which could only be used once.

In 1842 Talbot was awarded a medal from the Royal Society for his work in the progression of photography.

The work William Henry Fox Talbot had done on the calotype process, led to future inventors advancing the photographic process even further in the 19th and 20th centuries.

500px-Periodic_table.svgThe Periodic Table was first introduced by the Russian scientist Dmitri Mendeleev. Originally from Siberia, Mendeleev studied science at St Petersburg University, where he graduated as a chemist in 1856. By 1863 he was a Professor of Chemistry. Mendeleev first revealed his arrangement of 63 elements into his Periodic Table in his book, Principles of Chemistry, which was published in 1869.

Mendeleev’s Periodic Table was compiled on the basis of arranging the elements in ascending order of atomic weight, and grouping them by similarity of properties. Not only did he arrange these elements, but he also forward thinking enough to predict that other elements would be discovered in the future, and left spaces in the table where he believed they might fit into the chemical framework.

Dmitri Mendeleev wasn’t the first scientist to try and organise chemical elements into order. Beguyer de Chancourtois, Newlands and Lothar Meyer had all also worked on arranging the elements, but Mendeleev’s work surpassed all their individual attempts at classification.

It wasn’t until British chemist Henry Moseley (1887-1915), began work on developing the application of X-ray spectra to study atomic structure that a more accurate positioning of elements could be attained. He was also able to include the Nobel Gases, which had yet to be discovered in Mendeleev’s time.

When Moseley discovered that atoms should be arranged according to atomic number rather than weight, as Mendeleev had believed, The Periodic Table began to take on the appearance we recognise today.

The Periodic Table has been adapted and improved many times since Mendeleev’s initial design, but it remains one of the most important discoveries in Science, and one of the most recognisable tools in Chemistry.

 

 

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