Knot theory A knot diagram of the trefoil knot Knots can be described in various ways. Given a method of description, however, there may be more than one description that represents the same knot. A complete algorithmic solution to this problem exists, which has unknown complexity. History Archaeologists have discovered that knot tying dates back to prehistoric times. A mathematical theory of knots was first developed in 1771 by Alexandre-Théophile Vandermonde who explicitly noted the importance of topological features when discussing the properties of knots related to the geometry of position. In the late 1970s, William Thurston introduced hyperbolic geometry into the study of knots with the hyperbolization theorem. Knot equivalence On the left, the unknot, and a knot equivalent to it. The basic problem of knot theory, the recognition problem, is determining the equivalence of two knots. Knot diagrams Reidemeister moves In 1927, working with this diagrammatic form of knots, J.
The Experiment Is on Us: Science of Animal Testing Thrown Into Doubt (Photo: ressaure)New scientific research has cast grave doubt on the safety testing of hundreds of thousands of consumer products, food additives and industrial chemicals. Everyday products, from soft drinks and baby foods, to paints, gardening products, cosmetics and shampoos, contain numerous synthetic chemicals as preservatives, dyes, active ingredients, or as contaminants. Official assurances of the safety of these chemicals are based largely on animal experiments that use rabbits, mice, rats and dogs. The results of these experiments challenge the longstanding scientific presumption holding that animal experiments are of direct relevance to humans. The research originated when investigators noted that in their medical specialism of inflammatory disease (which includes diabetes, asthma and arthritis), drugs developed using mice have to date had a 100% failure rate in almost 150 clinical trials on humans. In further experiments, the researchers identified another difference.
SciVee | Making Science Visible DNA from the Beginning - An animated primer of 75 experiments that made modern genetics. Digital Drawing Board Creates Objects in Stunning 3D Detail ETOS, or Electronical Tool for Object Sketching, is a tool for designers and architects that lets them see their creations in three dimensions without the need for 3D glasses. The tool uses the familiar shape of a pen and the intuitive function of a touch interface to bring sketches into the real world. The drawing board takes the form of a tablet computer with a built-in stand formed from its folded cover. It displays objects in 3D using lenticular lens technology and motion tracking, which also allows users to move the shapes around with their hands. The pen-shaped input tool performs basic editing functions that are selected by simply turning it along the horizontal or vertical axis. Secondary functions can be selected by tapping the touch screen with 1-4 fingers.
Reprogrammed bacterium speaks new language of life - life - 17 October 2013 Read full article Continue reading page |1|2 Read more: To read a fuller version of this story, click here A bacterium has had its genome recoded so that the standard language of life no longer applies. The work has been described as the first step towards a new biology because the techniques used should open the door to reinventing the meaning of several genetic words simultaneously, potentially creating new types of biomaterials and drugs. The engineered bacteria, dubbed genetically recoded organisms (GROs), have the added advantage of being resistant to many existing viruses. Alien architecture The four letters of the genetic code are usually read by a cell's protein-production machinery, the ribosome, in sets of three letters called codons. Although there are 64 ways of combining four letters, only 61 codons are used to encode the 20 amino acids found in nature. A team of synthetic biologists led by Farren Isaacs at Yale University have now fundamentally rewritten these rules.
Interactive Lesson Calculating The Odds of Intelligent Alien Life Astronomers believe that every star in the galaxy has a planet, one fifth of which might harbor life. Only we haven't seen any of them — yet. Jeremy Kasdin and his team are looking to change that with the design and engineering of an extraordinary piece of equipment: a flower petal-shaped "starshade" that allows a telescope to photograph planets from 50,000 kilometers away. It is, he says, the "coolest possible science." Visit the SETI Institute online to learn more about their work, the scientists on their team and the intiatives they are spearheading in the search for extraterrestrial life. Explore the SETI@home project, which harnesses the power of home computers around the world to aid in the search for alien life. Watch Jill Tarter's call to join the SETI search on TED.com
Eat, Drink and Live Forever: Immortality is 20 Years Away It seems that we’ve been edging toward becoming a race of cyborgs for a number of years. Medical advances like replacement limbs and joints, cochlear implants, and artificial organs are already being used. Improving medical technology and our understanding of anatomy will continue to drive the human race toward immortality, according to scientist Ray Kurzweil. He believes that within 20 years, there will be no need for humans to face death at all. Nanotechnology will be applied to create artificial vital organs and even artificial blood cells. Kurzweil and other scientists believe that by using nanotechnology, we can reprogram our bodies’ “stone-age software” to halt the aging process, then do away with death altogether. In Kurzweil’s perception of the future, we’ll all sport cybernetic limbs and organs, and rely on nanobots to keep us alive through traumatic injuries and illnesses.
A bees-eye view: How insects see flowers very differently to us By MICHAEL HANLON Last updated at 08:52 08 August 2007 To the human eye, a garden in bloom is a riot of colour. Flowers jostle for our attention, utilising just about every colour of the rainbow. But of course, it is not our attention they need to attract, but that of insects, the perfect pollinating agents. And as these remarkable pictures show, there is more to many flowers than meets the eye - the human eye at least. The images, taken by Norwegian scientist-cameraman Bjorn Roslett, present a series of flowers in both natural and ultraviolet light, revealing an insect's eye view. Scroll down for more Ultraviolet light, invisible to us, uncovers colours and patterns which drawthem to the source of pollen and nectar - all hidden to humans without special equipment. This secret colour world was discovered in the Fifties and scientists realised that these distinct patterns were designed to act as "landing strips" or arrows, guiding the insects to the right spot.
Video clips on a range of Science topics Appendicitis? Human Appendix Maybe Not Useless After All For a long time, we’ve believed that the human appendix was more or less good for nothing. Darwin postulated that the appendix was a remnant of evolution that was no longer needed. But for the first time, researchers are actually taking a close look at the appendix and its function. And they’ve come to believe that it is, after all, good for something: it may help to restock the stomach with good bacteria after an illness, like a bout of diarrhea. (image via: ashe-villain) Scientists and researchers from Duke University Medical Center, the University of Arizona and Arizona State University collaborated on the study, which concluded that not only is the appendix not useless – it’s also been around far longer than anyone previously thought.
BBC Nature - Dinosaur gases 'warmed the Earth' 7 May 2012Last updated at 10:43 By Ella Davies Reporter, BBC Nature Apatosaurus, formerly known as Brontosaurus, produced a lot of wind Giant dinosaurs could have warmed the planet with their flatulence, say researchers. British scientists have calculated the methane output of sauropods, including the species known as Brontosaurus. By scaling up the digestive wind of horses, they estimate that the total population of dinosaurs, produced 520 million tonnes of gas annually. They suggest the gas could have been a key factor in the warm climate 150 million years ago. David Wilkinson from Liverpool John Moore's University, and colleagues from the University of London and the University of Glasgow published their results in the journal Current Biology. Sauropods, such as Apatosaurus louise (formerly known as Brontosaurus), were super-sized land animals that grazed on vegetation during the Mesozoic Era. Previous studies have suggested that the Earth was up to 10C (18F) warmer in the Mesozoic Era.