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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 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 Christopher Adriaanse
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Friday, 09 October 2009 |
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Check out the new issue of BlueSci Click here for the pdf
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