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A pill might replace that third helping of turkey at future Thanksgiving and Christmas dinners. A newly-discovered chemical found naturally in our body blocks hunger and weight gain.

Mice and rats - and presumably humans - produce the chemical after eating a fatty meal. When researchers gave the rodents an extra dose, they ate less and shed weight, with no ill effects.

If similar tests in larger animals pan out, humans will be next, says Gerald Shulman, a molecular biologist at Yale University in New Haven, Connecticut whose team discovered this new role for the molecule, called N-acylphosphatidylethanolamine (NAPE).

"We have this epidemic of obesity and we have very few agents that are able to effectively treat obesity," he says. "We'd be quite interested in trying a clinical trial to see if giving this back would reduce food intake in humans."

Fatty foods, be they milkshake, French fry or Big Mac, have long confounded researchers seeking to explain how our body determines when it has had enough. Levels of fatty acids - the building blocks of junk foods - actually fall when people gorge on greasy foods, only to increase with hunger.

This peculiar behaviour prompted Shulman, Yale biologist Matthew Gillum and their colleagues to scour blood for compounds that shot up after a fatty meal.

NAPE fit the bill. Fatty acids in food get converted to NAPE in the gut before heading to the bloodstream. From there, the chemical races into the brain's appetite centre, in the hypothalamus, and shuts down neurons involved in signalling hunger, Shulman's team found.

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The world's forests - and the billion people who depend on them - are facing devastation from climate change unless we "evolve" with the changing situation, according to a new report.

The Center for International Forestry Research (CIFOR) reviewed the scientific literature on the effects of climate change on forests and concluded that it will have a dramatic effect on forests, irrespective of the future rate of greenhouse-gas emissions.

Within the next 100 years, tropical regions are likely to heat up at a faster rate than the global average. Rainfall and summer monsoons will increase in some areas, while annual rainfall will decrease in others; tropical cyclones may become more severe, and droughts, floods and wildfires are likely to be more common, according to the report (pdf format).

Unless immediate adaptive action is taken, says lead author Bruno Locatelli of CIFOR, these changes will lead to a self-perpetuating cycle, where destruction of the forests leads to an increased amount of carbon in the atmosphere, which will in turn cause further climate change, and so on. The report identifies two categories of adaptation.

"The first is to buffer ecosystems against climate-related disturbances like improving fire management to reduce the risk of uncontrolled wildfires or the control of invasive species," he says. "In plantations, we can select species that are better suited to coping with the predicted changes in climate."

"The second would help forests to evolve towards new states better suited to the altered climate," Locatelli says. "In this way we evolve with the changing climate rather than resist it."

Efforts to deal with the problem tend to focus on reducing deforestation, but the report calls for more emphasis on urgent adaptation measures to help the forests and forest communities to cope with the inevitable changes. "In this way we evolve with the changing climate rather than resist it," he says.

Dave Reay, a climate-change researcher at the University of Edinburgh, UK, agrees with the recommendations, but points out that mitigation is still key.

"Much more important than climate-change impacts, in terms of the next few decades, is human activity," he says. "It's deforestation and degradation - that's what's going to destroy these huge carbon sinks before climate change has a chance to get at them."

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THE US air force is seeking to develop a cluster weapon that releases a swarm of bomblets that could each pursue and destroy targets many kilometres away, New Scientist has learned.

"This is a dangerous and very worrying development," says Noel Sharkey, a specialist in the ethics of autonomous systems at the University of Sheffield in the UK. Sharkey has argued that giving a robot the power to decide when and who to attack raises serious practical and ethical questions, and says the same would apply to the proposed weapon.

The US Department of Defense revealed its requirements for the weapon in an online research request. In it, the air force asked American aerospace firms to submit proposals by 24 September for a weapon that "engages multiple targets" using "guided smart submunitions". The request says the submunitions - the formal term for bomblets - should be equipped with sensors capable of locking on to targets up to 5 kilometres away, and should have enough onboard power to chase a moving target for up to 5 minutes.


"These new bomblets would effectively be miniaturised air-to-surface missiles," says Colin King, an analyst with Jane's, a defence publisher based in the UK.

The air force hopes the guided weapons will "increase accuracy and reduce collateral damage". That will depend on the reliability of the weapon's decision-making software and its sensors, although according to Sharkey there is no way these "smart" submunitions will be able to distinguish between combatants and civilians. "If a target moves into a highly populated area, I can't think of any sensors that could reliably discriminate between civilian and military vehicles," he says.

Existing "smart" cluster bombs scatter bomblets equipped with lasers and infrared sensors, which allows them to identify targets such as tanks and trucks. That's not necessarily enough to tell friend from foe, but at least their range is limited - to about 350 metres in the case of the US-made BLU-108. The proposal, however, calls for bomblets that lock back on to targets if they happen to lose track of them, meaning they might lock on to the wrong vehicle.

"The distinction between military and civilian targets cannot be made by electronics: it has to be a human decision," says Richard Moyes of Landmine Action in London. "Relying on computerised sensors to attack targets raises fundamental moral and legal questions."

It's not clear if such weapons would breach the Convention on Cluster Munitions due to be signed by 109 countries in Oslo in December. The CCM permits cluster weapons as long as they can reliably identify targets and deactivate or self-destruct if they miss. The US is not signing up, because it says it is building weapons intelligent enough to render themselves harmless if they stray off course (New Scientist, 7 June, p 25).

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Mumbai: At least 80 people, including a foreign tourist and four top police officers, were killed and over 250 injured as terrorists struck in yet another series of planned and synchronised gunfire and bomb attacks in the heart of India's financial capital late on Wednesday, authorities said.

Terrorists were reported to be holding tourists and other guests hostage in two five-star hotels, the Taj Intercontinental and Trident (formerly Oberoi), facing the waterfront across the Arabian Sea close to the city's most important landmark, the Gateway of India.

Four top police officials, including Anti-Terrorism Squad (ATS) chief Hemant Karkare, were among the 10 policemen killed in the gunbattles with the terrorists, police confirmed.

Among terror targets was the city's busiest railway station, the Chhatrapati Shivaji Terminus (CST), formerly the Victoria Terminus that is a World Heritage site.

A nationwide alert was sounded and all airports in the country put on high-security surveillance following the attacks that came less than a month after over 50 people died in serial terror bombings in the northeastern state of Assam.

Army was called in to bring the situation under control and restore the sense of security in the city that was literally shaken the attacks, one of the worst in the country.

"This is a most audacious attack. It is a very serious situation and gun battles are still on in at least three places," said Maharashtra Chief Minister Vilasrao Deshmukh.

Mumbai Police Commissioner Hasan Ghafoor said the attacks were suspected to be "coordinated terrorist acts", and added that automatic weapons like AK-47 and AK-56 and semi-automatic rifles as well as grenades were apparently used.



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It seems we got off lightly in the cosmic lottery. Deadly comet impacts may be much rarer in our solar system than in others nearby.

We can't directly measure the rate of comet collisions in other solar systems but we can detect signs of the dust that such smashes kick up because the dust gets warmed by the star and so gives off infrared radiation. That radiation shows up as extra infrared in the spectrum of light coming from the star. Because such dust should dissipate quickly, it is thought to provide a good snapshot of the recent collision rate.

Jane Greaves of the University of St Andrews, UK, analysed observations by the Spitzer Space Telescope and found that the vast majority of sun-like stars near us have more dust than our solar system does and therefore have had more collisions in their vicinity. Our solar system may be one of the few that have been safe for life. Greaves presented her results at the Cosmic Cataclysms and Life symposium in Frascati, Italy, this month.

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Our impact on Earth's climate might be even more profound than we realise. Before we started pumping massive amounts of carbon dioxide into the atmosphere, the planet was on the brink of entering a semi-permanent ice age, two researchers have proposed.

Had we not radically altered the atmosphere, say Thomas Crowley of the University of Edinburgh, UK, and William Hyde of the University of Toronto in Canada, the current cycle of ice ages and interglacials would have given way in the not-too-distant future to an ice age lasting millions of years.

"It's not proven but it's more than just an interesting idea," says Crowley.

For much of the 500 million years or so since complex life evolved, Earth's climate has been much hotter than it is now, with no ice at the poles. During the last of these "hothouse Earth" phases, from around 100 to 50 million years ago, the Antarctic was covered by lush forests and shallow seas submerged vast areas of America, Europe and Africa.

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Supersonic jets of water vapour are blasting from Saturn's moon Enceladus, reveal observations from NASA's Cassini spacecraft. Some say the newly discovered features bolster the case for a reservoir of liquid water - which could potentially host life - just beneath the moon's surface.

The high-powered jets lie within wider plumes of water vapour and ice, found in 2005, which extend hundreds of kilometres from the moon's south pole.

The supersonic jets were detected during a flyby on 24 October 2007, when the probe's Ultraviolet Imaging Spectrograph (UVIS) observed a star as it passed behind the plumes. By measuring how much starlight was absorbed during the passage, scientists discerned four distinct jets in the plume.

The jets were still tightly focused at an altitude of 15 km above the surface, suggesting they were moving faster than 2100 km per hour. Such high speeds imply that the jets are fed by pressurised water vapour that shoots through narrow openings - which act like rocket nozzles - in the moon's icy surface.

The simplest way to generate such pressures is by evaporating a reservoir of liquid water that lies close to the moon's surface, says lead author and UVIS team member Candice Hansen of NASA's Jet Propulsion Laboratory in Pasadena, California. The heat needed to evaporate the water might be generated in part by Saturn's gravity, which squeezes and stretches the moon.

But some researchers say the plumes might originate from subsurface ice instead. In one scenario, the strains from Saturn's tugs could cause a shell of ice to grind and vaporise, particularly if the shell lay over a 'lubricating' ocean of liquid water buried relatively deep below the surface.

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Electric vehicles are all the rage, but few have pushed the design envelope as far as the Aptera Typ-1, which hits the streets of California in December. Aptera Motors claims that its vehicle can travel up to 190 kilometres on a single charge, aided by roof-mounted solar cells. The vehicle, which is officially classified as a motorbike, will sell for $27,000.

A petrol/electric hybrid version with a longer range is due to be launched in 2009 for $30,000.

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Should you get off the motorway now, or carry on and hope the traffic clears? Your cellphone could soon have the answer.

Researchers at Nokia and the University of California, Berkeley, have developed a system that collects GPS data from mobile phones in moving vehicles and uses it to create traffic maps. The maps are available on the internet or sent to your cellphone to provide local traffic analysis.

Alex Bayen at UC Berkeley says that if enough people download the free software (from http://traffic.berkeley.edu), the system should help relieve congestion, even on small intercity roads. And in case you're worried that the neighbours will now be able to follow your every move, he says that the system anonymises GPS data so that it will be impossible to track individual cars.





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