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Written by Wendy Mak
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Friday, 05 February 2010 |
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Using silicon nanowires for the next generation of computers requires careful consideration Researchers at the Max Planck Institute in Halle, have been looking at the electrical properties of monocrystalline silicon nanowires implanted with foreign atoms (dopants) such as born and phosphorous. These atoms should help in increasing the electrical conductiveiy of the nanowires, but so far, no one has characterised the behaviour of these dopants in detail. Computer chips are getting smaller and more powerful by packing more transistors into the same space. Up until now all these structures have been two dimensional. A possible route to new chip architecture is to make them three dimensional, by building tansistors which stick out of the substrate. These transistors could be made of silicon nanowires and while fabrication of three dimensional arrays of these wires has been achieved, there is little known about how to modify the electrical properties of the wires to make them more reliable and efficient. Using a technique known as scanning spreading resistance microscopy, SSRM, the researchers looked at nanowires with diameters of 100nm to 300nm. They found that the dopants tend to drift to the surface of the wires, which partially inactivates them. These new results are important when considering the design of three dimensional chips and could make the difference between having chips with superior function or having a useless chip! |
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Written by Elizabeth Bateman
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Thursday, 04 February 2010 |
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Organic transistors lead the way towards neuro-inspired computers. Researchers at the CNRS and CEA have developed a transistor that mimics the functionalities of a synapse. This organic transistor known as NOMFET (Nanoparticle Organic Memory Field-Effect Transistor) is capable of responding in a similar manner to the nervous system. The result comes from the pursuit of new information processing strategies. This approach has attempted to imitate the way biological systems, such as neural networks, operate. In the nervous system, a synapse is the junction between two neurones, enabling the transmission of electric messages from one neuron to another and the adaptation of the message as a function of the nature of the incoming signal (plasticity). For example, if the synapse receives very closely packed pulses of incoming signals, it will transmit a more intense action potential. Conversely, if the pulses are spaced farther apart, the action potential will be weaker. It is this plasticity of the transmission of an action potential that has been successfully mimicked with the organic transistor. Normal transistors form the basic building block of most electric circuits.They can function as amplifiers, modulators and encoders but are widely used as a switch for an on/off signal. The NOMFET transistor also has an innovative memory effect which has allowed the imitation of a synapse during action potential transmission. This advancement was achieved by combining the transistor with gold encapsulated nanoparticles, fixed in the channel of the transistor and coated with pentacene. The resulting performance is comparable to the seven CMOS transistors (at least) previously needed to mimic this plasticity. The devices produced have been optimized to nanometric sizes in order to be able to integrate them into neuro-inspired computers. These can resolve much more complex problems than present silicon computers, such as visual recognition. |
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Written by Laura Soul
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Thursday, 04 February 2010 |
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Basic chemical exchange processes have been observed directly for the first time. During chemical reactions there are complex underlying processes that determine when bonds between molecules break or form. Now, a team of scientists in Austria led by Professor Rudolf Grimm have managed to control these processes, allowing the reactions to be directly observed. To do this they took a cesium gas compsed of both atoms and molecules, cooled it down to one millionth of a Kelvin above absoloute zero and trapped it in a confined space. They then applied a microwave pulse and a magnetic field. This allowed them to control the energy at which exchange reactions within the gas occurred. Due to this control, when an exchange reaction happened the energy released was very low, so the products of the reaction remained trapped, this was the key in allowing the whole process to be observed from start to finish. This ability to directly observe the process will help scientists to understand why and how it happens outside of the lab. "A totally new field of research opens up, which promises possibilities to study diverse chemical reactions in a controlled way" explains Grimm. |
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Written by Alex Hyatt
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Saturday, 30 January 2010 |
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Could bacteria be used to power our machines? Researchers in America have taken some important steps towards creating a system in which bacteria do some mechanical work.This is tricky as bacteria tend to swim in random directions and each individual weighs almost nothing, so designing a system that can harness energy from them is a daunting challenge. The researchers have now developed a set of microscopic gears that concentrate bacteria on only one side of each "gear tooth", causing the bacteria to pool at that edge and as they swim against it, they force the gear to turn in a single direction. Linking up two of these gears together, the bacteria were able to keep them spinning continuously for nearly two minutes. This is incredibly impressive considering that each bacterium is millions of times less massive than one of these gears. In the future, it may be possible to create much larger devices that can extract more substantial amounts of energy.
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Written by Taylor Burns
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Friday, 29 January 2010 |
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The world's most mysterious and inaccessible bird has been discovered in Afghanistan. Swedish ornithologists, in cooperation with Afghan and American researchers, have located the Large-billed Reed warbler in northeastern Afghanistan. This a small and exceedingly rare bird. Initially discovered in 1867, it has only been observed three times in the proceeding 142 years, until now. In 2008, Lars Svensson and Urban Olsson of the University of Gothenburg speculated that northeastern Afghanistan was a breeding site for the Warbler, spurred on by an American discovery of unidentifiable bird song that same year. Then, in 2009, Afghan ornithologists Naqeebullah Mostafawi, Ali Madad Rajabi and Hafizullah Noori were able to travel to the hostile region, capturing 15 birds from the unclassified species. DNA analyses in Sweden confirmed that, after a century and a half, the epicenter of the world's most inaccessible bird had been found.
The Large-billed Reed warbler, approximately 13-14 centimeters long and the rarest of its bird family,
was found in the Wakhan region of north-eastern Afghanistan, running between Tajikistan, Pakistan and China, up to the Himalayan mountains. The region, although rich in bird life, takes several days to reach and is subject to frequent violent conflicts, making research difficult. Locating the bird, regarded as under acute threat in the ornithological community, will aid further research as well as allow for possible conservation attempts. |
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Written by Wing Ying Chow
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Friday, 29 January 2010 |
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Lopsided jaw helps fish to eat. Thomas Stewart and Craig Albertson from Syracuse University in New York have been looking at lopsided fish from Lake Tanganyika in Africa and trying to understand how this asymmetry comes about. These cichlid fish have a very specific diet. They eat scales from other fish. To facilitate this, they have asymmetrical jaw and head shapes, as this allows them to graze scales off one side of theirprey more easily. The principle of natural selection dictates that the fish cannot all pick the same side, as their prey would learn to avoid swimming on the side that makes them vulnerable to grazing. Thus, the population of adult scale-eating cichlids can be divided generally into 'righty' and 'lefty' individuals. The
researchers modelled the mechanics of the jaws and predicted that the side that curves closer to the prey is faster and possibly more efficient at snipping scales off. The researchers wanted to find out how genetic and development factors contribute to jaw asymmetry - is it nature or nurture? To achieve this, they collected over a hundred larval fish whose head and facial
skeleton is still in development. They found that instead of having only distinct leftys and rightys, larval fish with symmetric or nearly symmetric jaws were also found. However, as these larval fish are good at grazing from neither left or right, they are more likely to starve; natural selection acts against them. Even though previous work have indicated that leftys are genetically dominant, the combined processes of development and selection means that most of the fish that make it to adulthood are rather lopsided, half on the right and half on the left. |
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Written by Jake Harris
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Thursday, 28 January 2010 |
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From the moment he started speaking, Lord Robert Winston's rumbling voice and trademark moustache captivated the audience. Though Winston had apparently no talk prepared and seemed to be winging the whole show, he managed to sustain an entertaining and informative performance throughout. The theme of the talk was the relationship between science and the public. Winston began with an amusing anecdote about how he got into television by accidentally performing his first caesarean section in front of a BBC television crew. He continued by discussing how science frequently makes developments that are as much a threat to human life as they are of benefit and how this can result in the public viewing science with general suspicion. In his opinion the problem is compounded by the way science is portrayed by the media, with some newspaper basing stories on the personal agendas of their editors rather than the facts. Also of interest was his opinion of medicine. Winston forged his varied and successful career from medicine, but was frequently disillusioned with the narrow minded and authoritarian way in which medics are trained. Indeed, at one point he quit medicine altogether to become a theatre producer. Winston responded well to questions from the audience, providing eloquent responses to issues including nuclear power and the public perception of GM foods. Ultimately, Winston presented a not too science-heavy talk about the nature of science, littered with entertaining stories from his life, which were well received by the packed out audience. |
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Written by Wendy Mak
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Wednesday, 27 January 2010 |
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A recently discovered chemical catalyst could turn carbon dioxide in the air into useful chemicals. Bouwman and colleagues at Leiden University in the Netherlands have managed to convert carbon dioxide into useful substances with a catalyst based on copper. Left in air, the chemical reacts with carbon dioxide to form a compound with an oxalate fragment. With a small electrical input, it is possible to dissociate the original compound from the oxalate. The oxalate could then be used to form many useful chemicals, such as oxalic acid, a component in some household products such as anti-rusting treatment; and with further processing, ethylene glycol, which is used as an antifreeze and for further chemical synthesis. This method of producing oxalate uses much less energy than conventional methods. However, this compound is unlikely to be used widely as a measure to combat global warming, as the efficiency is very low. Whereas a good catalyst can undergo thousands of cycles in operating conditions, the copper catalyst can only achieve around one cycle per hour in pure carbon dioxide, meaning that its efficiency in air is likely to be even lower. Still, the fact that such a compound exists could drive further research into similar substances. Perhaps one day soon, we would have factories that help to combat global warming by removing carbon dioxide from air, while producing useful chemicals at the same time.
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Written by Jake Harris
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Wednesday, 27 January 2010 |
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Shorebirds in Canada have been forced to lose weight and adapt their diet to escape rising numbers of Peregrine Falcons. A team of ecologists lead by Roland Ydenberg have pooled data spanning 40 years and seen that the weight of Pacific Dunlins has decreased by 2-4g since the 1960's. They believe that this weight loss correlates with the ban on DDT imposed in Canada during the 1970's: the chemical was poisoning the country's Falcon population. Since the ban, the population of Falcons has steadily increased and it is this increase that has forced the dunlins to lose weight, by spending more time in flight to avoid these new predators. Ydenberg says, "In the past, dunlins stored up fat reserves in the autumn months so that they could survive the harsh Canadian winters when food is short. What we’re seeing now, however, with the increase in numbers of peregrine falcons, is that the dunlins have to consider the energy trade-off between preparing for starvation and being able to escape quickly". The Dunlins are also being forced to travel long distances to find new, safer places to roost. They also now travel in flocks for 'safety in numbers'. This group technique, however, is energetically expensive and it is this sort of activity that is resulting in the loss of weight. Team member Dick Dekker explains "The risk from predators is now greater than the threat of starvation". The Dunlins have to find a balance between using energy to escape the falcons and storing up their reserves to survive the hard winters. |
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Written by Laura Soul
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Wednesday, 27 January 2010 |
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Scientists develop iridescent, self-cleaning surfaces which imitate the natural world. Superhydrophobicity (extremely water repellent) is a highly desired functional property in many modern materials. Superhydrophobic surfaces not only repel water but are also effectively self cleaning. Iridescence is another desired property and is found in everything from cars to clothing. Superhydrophobicity and iridescence are relatively difficult to manufacture; materials which simultaneously display both properties are rarely made, due to the structural constraints of each. Now scientists in China have imitated a naturally occuring superhydrophobic material - the lotus leaf to produce a surface which has both properties. The surface of their material is made up from millions of 'nanoneedles'. This vastly reduces the surface area of the material which comes into contact with a water droplet. The result as a reduced surface tension, allowing the water to bead-up and roll off, in the same way it does on a lotus leaf. The nanoneedles are made using lasers in a technique that is quick and simple when compared to previous methods used for making similar surfaces. There are wide ranging applications for such a material and the comparative ease of the method means that it could be mass produced. |
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Written by Alex Hyatt
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Monday, 25 January 2010 |
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Some of the world's oldest trees are experiencing a growth spurt By measuring tree rings of the Great Basin Bristlecone Pine, researchers have found that they have grown the most in the last 50 years of the 20th century than any other 50 year period. Importantly, the scientists were able to link this growth to increasing regional temperatures. The Great Basin Bristlecone Pine can live for over 4700 years, making it one of the longest living organisms on the planet. A team of scientists in the United States have been studying these ancient trees in an effort to understand how the climate has changed over the last few thousand years. This study provides evidence that the global warming occurring now is unlike any other warming event of the last four millennia. The trees may be enjoying the extra bit of warmth for now, but if we can't slow down this rapid climate change, I doubt they will continue to respond so positively.
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Written by Taylor Burns
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Sunday, 24 January 2010 |
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Researchers at the Babraham Institute have, for the first time, demonstrated that T cells, a type of white blood cell that plays a central role in the body's immune response, can be tailor-made. Active T cells, developed in the thymus from a complex cocktail of biochemical signals and intracellular genetic changes, are akin to the body's security surveillance system, detecting and administering to viruses and infections. As we age, the thymus shrinks, producing fewer T cells. This is a normal occurrence that has little effect on healthy bodies. However, in individuals with HIV/AIDS, chemo/radiotherapy and bone marrow transplants, the body's ability to replace T cells is severely compromised, leaving us with fewer, less diverse cells patrolling our immune system and putting us at greater risk of infection. The international team of academic and industrial immunologists, have discovered that a group of signaling proteins, called Phosphoinositide 3-kinases (PI3KS), known to transmit signals from external receptors to the inside of the cell, have multiple signalling functions involved in the creation of T-cells. One signalling molecule, called PI3K-p110g, carries signals from a receptor known as CXCR4, which then binds to the chemokine CXCL12 that is produced in the thymus. When isolated from the thymus, T cells could continue their developmental program if cultured in the presence of CXCL12, bringing scientists one step closer to the ideal of full T cell development without feeder cells. Besides progressing invitro T cell development, this discovery could also be valuable in clinical settings, where uncontaminated T cells are needed for transplantation and regenerative medicine.
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Written by Wing Ying Chow
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Sunday, 24 January 2010 |
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Researchers in China have discovered a link between cultivating rice and
blushing after drinking alcohol. Those of us who are Asian or have Asian friends may have noticed their tendency to blush rapidly and deeply after drinking very small amounts of alcohol. Researchers from Kunming and Beijing in China may have uncovered part of the puzzle as to why this alcohol flush happens. The group have shown that people who blush have a genetic mutation, making them more efficient at converting alcohol into aldehyde. Aldehyde is formed when the liver breaks down alcohol and is toxic to the body. The researchers looked at this genetic mutation in 38 populations across China. Their results show an increase of this mutation from west to east, with a dominance in south-eastern populations. This pattern ties in with the distribution of rice cultivation in China; rice is more widely cultivated in the warmer, mild climate of the south. The researchers propose that as rice can be easily fermented to make alcoholic beverages and food, the efficient conversion of alcohol to aldehyde is beneficial in two ways: Firstly it reduces the effective exposure of the body to alcohol and secondly the build up of aldehyde prevents addiction to alcohol due to the uncomfortable toxic effects. Growing rice and eating rice-derived fermented foods, have exerted an evolutionary pressure on the southern Chinese population to evolve biochemical defenses against alcohol. Blushing is an unfortunate side effect, but is nothing to be embarrassed about! |
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Written by Laura Soul
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Thursday, 21 January 2010 |
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Brain cells in monkeys provide the key to our ability to deal with basic mathematical concepts. Our ability to handle abstract concepts is a huge part of our everyday life. From choosing what food to buy to finding a job, we are always using our mathematical ability. This ability in humans is complex and exactly how we manage it is still unknown. However, scientists at the University of Tubingen have now shed light on a possible beginning for the evolutionary path that led to our mathematical talents. The researchers taught Rhesus monkeys a basic numerical rule: 'less than' or 'greater than'. They were required to pull a lever to indicate whether a number of objects shown on screen was less than or greater than a reference value. The key discovery here was that a set of neurons belonging to the prefrontal cortex were used to make the decision. If the answer was 'less than' approximately half of these neurons would fire, if it was 'greater than' the other half would fire. The researchers claim that this set of neurons could have been easily modified during evolution to perform the complex mental tasks humans do every day. Many mental illnesses are caused by damage to this area of the brain; this advance could lead to developments in treating these illnesses. |
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Written by Nitika Somani
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Thursday, 21 January 2010 |
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Friendly bacteria thrive on a regular diet of apples Microbiologists from the National Food Institute at the University of Denmark have shown that a diet rich in apples helps the friendly bacteria, in the intestine of rats, to thrive.
The scientists analysed the microbial content of the rats digestive system after feeding them regularly on a diet rich in whole apples, apple juice, puree or pomace. They looked at the impact this diet had on the numbers of presumed "Friendly" bacteria found in the gut.
The levels of friendly bacteria found in the digestive system of the rats eating the apple rich diet was much higher than those who were not. Pectin, a component of dietary fibre, found in the apples is thought to help the bacteria produce short chain fatty acids that provide ideal pH conditions for the microorganisms to flourish and also a chemical called butyrate important for the health of the intestinal wall
Hence an apple a day keeps the doctor away seems to be true for rats. Further studies are needed to ascertain if the human digestive system also responds in the same way. |
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Written by Alex Hyatt
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Monday, 18 January 2010 |
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Scientists discover why algae produce toxin The algal species K. veneficum is known for producing a dangerous toxin that kills fish and poisons shellfish but until now it has been unclear exactly why it produces this toxin. Researchers in Baltimore Maryland have discovered that the main reason is likely to be that it helps them capture other algae to eat. Using three dimensional high-speed microscopy the researchers were able to track the movements of K. veneficum and its algal prey in the presence or absence of the toxin. When the toxin is present, the prey species swims over 50% more slowly and the number of immobile prey increases to over 90% after 5 hours. This is the first time anyone has been able to demonstrate this because of the difficulty involved in tracking single cells among thousands of individuals swimming around in solution. This finding should help researchers to better predict when and where toxic algal blooms will appear, as current models usually ignore the abundance of prey in their calculations. And hopefully this will lead to fewer people getting sick from eating toxic shellfish too. |
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