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Monday, 22 October 2007

News from NewScientist


Speeding up fat metabolism may prevent diabetes



RAMPING up fat metabolism doesn't just stop weight gain - it could also prevent type 2 diabetes.


Previous studies had shown that mice engineered to lack an enzyme called acetyl-CoA carboxylase 2 (ACC2) deposited less fat in their tissues, despite eating up to 40 per cent more than normal mice. Because fatty deposits around the liver can lead to insulin resistance and type 2 diabetes, removing ACC2 should also protect mice from diabetes.


There was a catch, however. For years, researchers had thought that burning more fat meant less carbohydrate would be used up. "This is the Randle hypothesis," says James Ntambi at the University of Wisconsin-Madison. "In one metabolic pathway you generate intermediates that inhibit the enzymes of the other metabolic pathway."


If this was the case, removing ACC2 could cause carbohydrate levels to rise - leading to excessively high blood sugar, insulin resistance and so on...


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Lap dancers 'in heat' are the ones to watch


Last month, biologist Randy Thornhill challenged the orthodoxy that women do not undergo regular bouts of hormone-induced oestrus, or "heat", when they are at their most fertile - something most female mammals experience (New Scientist, 15 September, p 18). Now a study of the tips men give to lap dancers, conducted by a colleague of Thornhill's, lends further support to the argument for oestrus.


Geoffrey Miller and his team at the University of New Mexico, Albuquerque, compared the earnings of lap dancers who were menstruating naturally with those of dancers taking the hormonal contraceptive pill. During the non-fertile periods of their menstrual cycle, both sets of dancers earned similar tips. But when naturally cycling lap dancers entered their fertile period they earned significantly more in tips than their co-workers on the pill.


This is the first evidence that oestrus, and its influence on attractiveness, has "a real effect on women's earnings", says Miller.


However, even on non-fertile days lap dancers with natural menstrual cycles still earned reasonable tips, reinforcing the idea that men are clearly paying for the lap-dancing experience rather than for any perceived opportunity to procreate.


"Previous research has shown that women's faces, scent and clothing become more attractive in oestrus," Miller notes. For example, earlier this year, Martie Haselton at the University of California, Los Angeles, found that women were judged to dress more attractively during their fertile periods, although the correlation was slight. Other studies show women become more confident during oestrus, says Thornhill. In the context of lap dancing, that may subtly change their behaviour and make them more appealing to clients.


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Virtual human has a roving eye


Virtual characters that meet your gaze just like a human have been developed by speech and cognition scientists in France.


New software lets them to look at scenes and people the way humans do. The goal is to make virtual humans and perhaps humanoid robots easier to relate to. A video (see right) shows one of their characters playing a game that involves looking at cards and a researcher.


We all know how uncomfortable it feels when we talk to someone who doesn't hold eye contact with us, or holds it too much. Virtual characters and robots are even worse – leading to stilted encounters.


Humans and other animals do not steadily scan a scene. Instead, our eyes constantly dart around in rapid unconscious jerks known as 'saccades'. They pin-point interesting parts of the scene the brain uses to build up a 'mental map'.


GĂ©rard Bailly and colleagues in the GIPSA Lab at the Institut National Polytechnique de Grenoble, France, have developed software that mimics human gaze patterns. Their characters are capable of saccades, tracking moving objects like humans, and fixing their gaze on the same features as humans for similar periods.


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Are mirrors the best way to deflect asteroids?


Focusing sunlight onto an asteroid with space-based mirrors is the best way to deflect Earth-bound space rocks, a new study finds. The mirrors beat out nuclear blasts and "gravity tractors" in the study, which compared nine different deflection methods.


Asteroids larger than 5 kilometres across – such as the one that killed off the dinosaurs – hit Earth about once every 6 million years. But smaller space rocks spanning about 140 metres strike more often, about once every 5000, and they can cause significant damage.


Now, researchers led by Massimiliano Vasile of the University of Glasgow in Scotland have compared nine of the many methods proposed to ward off such objects, including blasting them with nuclear explosions.


The team assessed the methods according to three performance criteria: the amount of change each method would make to the asteroid's orbit, the amount of warning time needed and the mass of the spacecraft needed for the mission.


The method that came out on top was a swarm of mirror-carrying spacecraft. The spacecraft would be launched from Earth to hover near the asteroid and concentrate sunlight onto a point on the asteroid's surface.


Vaporise surface

In this way, they would heat the asteroid's surface to more than 2100° C, enough to start vaporising it. As the gases spewed from the asteroid, they would create a small thrust in the opposite direction, altering the asteroid's orbit.


The scientists found that 10 of these spacecraft, each bearing a 20-metre-wide inflatable mirror, could deflect a 150-metre asteroid in about six months. With 100 spacecraft, it would take just a few days, once the spacecraft are in position.


To deflect a 20-kilometre asteroid, about the size of the one that wiped out the dinosaurs, it would take the combined work of 5000 mirror spacecraft focusing sunlight on the asteroid for three or more years.


Vasile admits that launching and controlling 5000 spacecraft is a daunting prospect. "I must say honestly that 5000 is really a lot," he told New Scientist. But he says launching a few dozen spacecraft to deflect a smaller asteroid is within our capabilities, pointing out that this many spacecraft were launched to create the Global Positioning System.


The mirrors came out ahead of the so-called gravity tractor option, in which a spacecraft simply flies alongside an asteroid and nudges it off course using the tiny force of the spacecraft's own gravity.


source



UK changes position on animal-human hybrids



WHAT a difference a year makes. Just 12 months ago, the British government said it would maintain a ban on creating embryos that contain both animal and human material. Now it is proposing that regulatory authorities be allowed to consider the creation of four types of hybrid embryo, including so-called true hybrids.


In 1990, the Human Fertilisation and Embryology Act banned researchers from creating hybrid embryos, but after a year of consultation, the government announced on 8 October its latest plans to update this legislation. The new proposals would allow researchers to create "chimeras" by adding animal cells to human embryos, "cybrids" by replacing the nuclear DNA of an animal egg with human DNA, true hybrid embryos by mixing human and animal sperm and eggs, as well as adding animal genes to human embryos.


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My comment: Eeewk :(


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