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the first planet has been found around a star that seems to be an interloper from another galaxy. curiously, the star also contains fewer heavy elements – thought to be needed to build planets – than any other planet-hosting star yet discovered.

the planet, which is 1.25 times as massive as jupiter, lies 2300 light years from earth and orbits a bloated, ageing star slightly less massive than the sun. johny setiawan of the max planck institute for astronomy in heidelberg, germany, and colleagues found the planet by the way its gravity caused its host star to wobble.

the host star, called hip 13044, is a member of a group of stars called the helmi stream that have unusual, elongated orbits that bring them far above and below the disc of the galaxy, where the sun and most other milky way stars reside. the helmi stars are thought to be remnants of a small galaxy torn apart by the milky way 6 billion to 9 billion years ago.

dearth of metals

astronomers announced a possible planet in the nearby andromeda galaxy in 2009, but its presence has not yet been confirmed. so this makes the newly found planet, called hip 13044 b, the first to be discovered around a star apparently from another galaxy.

"this cosmic merger has brought an extragalactic planet within our reach," says team member rainer klement, also of the max planck institute for astronomy.

in addition to its unusual origins, the host star is puzzling because it has fewer elements heavier than hydrogen and helium than any other star known to host a planet. its light spectrum suggests it has just 10 per cent as much iron as the previous record holder, and only 1 per cent as much as the sun.

planets are thought to form from discs of gas and dust left over from the formation of the parent star. in the prevailing theory of planet formation, called core accretion, dust grains stick together to form rocky worlds, and some of these rocky bodies then grow massive enough to attract surrounding gas, becoming gas giants like jupiter.

alternative scenario

dust is made up of heavy elements, so stars depleted in these elements would have a hard time making planets in this scenario.

this suggests the planet formed another way, says alan boss of the carnegie institution of washington, dc, who was not a member of the team.

he proposes an alternative mechanism that he has long championed, in which dense regions of the planet-forming disc simply collapse under their own gravity to form planets. in this scenario, planets could form mainly from gas, without first forming a rocky core.

he adds: "the fact that the star is also likely to have come from somewhere other than the disc of our galaxy makes it even more remarkable, and supports the suspicion that planetary systems are rife in the universe."

the first planet has been found around a star that seems to be an interloper from another galaxy. curiously, the star also contains fewer heavy elements – thought to be needed to build planets – than any other planet-hosting star yet discovered.

the planet, which is 1.25 times as massive as jupiter, lies 2300 light years from earth and orbits a bloated, ageing star slightly less massive than the sun. johny setiawan of the max planck institute for astronomy in heidelberg, germany, and colleagues found the planet by the way its gravity caused its host star to wobble.

the host star, called hip 13044, is a member of a group of stars called the helmi stream that have unusual, elongated orbits that bring them far above and below the disc of the galaxy, where the sun and most other milky way stars reside. the helmi stars are thought to be remnants of a small galaxy torn apart by the milky way 6 billion to 9 billion years ago.

dearth of metals

astronomers announced a possible planet in the nearby andromeda galaxy in 2009, but its presence has not yet been confirmed. so this makes the newly found planet, called hip 13044 b, the first to be discovered around a star apparently from another galaxy.

"this cosmic merger has brought an extragalactic planet within our reach," says team member rainer klement, also of the max planck institute for astronomy.

in addition to its unusual origins, the host star is puzzling because it has fewer elements heavier than hydrogen and helium than any other star known to host a planet. its light spectrum suggests it has just 10 per cent as much iron as the previous record holder, and only 1 per cent as much as the sun.

planets are thought to form from discs of gas and dust left over from the formation of the parent star. in the prevailing theory of planet formation, called core accretion, dust grains stick together to form rocky worlds, and some of these rocky bodies then grow massive enough to attract surrounding gas, becoming gas giants like jupiter.

alternative scenario

dust is made up of heavy elements, so stars depleted in these elements would have a hard time making planets in this scenario.

this suggests the planet formed another way, says alan boss of the carnegie institution of washington, dc, who was not a member of the team.

he proposes an alternative mechanism that he has long championed, in which dense regions of the planet-forming disc simply collapse under their own gravity to form planets. in this scenario, planets could form mainly from gas, without first forming a rocky core.

he adds: "the fact that the star is also likely to have come from somewhere other than the disc of our galaxy makes it even more remarkable, and supports the suspicion that planetary systems are rife in the universe."
(enlarge111, 19.11.2010 21:11)
loading... #25359716 * :o :( /msj ?

injecting bacteria into the bloodstream might sound like a health risk, but those propelled by a whirling helical tail, or flagellum, could one day be used to send messages between cancer-fighting nanobots.

maria gregori and ignacio llatser at the polytechnic university of catalonia in barcelona, spain, envision a future in which nanobots in the body sense tumour cells and release anticancer drugs to fight them. but one machine can't defeat a tumour single-handedly; it needs some way of telling the others to swarm on the target.

radio signals won't travel through a liquid, and chemical forms of communication using pheromones or calcium ions work only across large or microscopic distances. on the scale of a few millimetres – the distance from one blood vessel to another – there is no way to transmit information reliably.

so the pair came up with the idea of using bacteria with flagella, in this case a non-pathogenic strain of e. coli, to send the information. the idea is to encode a message in a dna sequence that is inserted into each bacterium's cytoplasm. each nanobot would contain bacteria inscribed with every message that could be needed

when a nanobot encounters a tumour, it would release the correctly encoded bacteria. these would then swim towards other nanobots, attracted by the nutrients stored there. once there, the encoded dna sequence binds with chemical receptors and its message – telling it where to swarm or to release its drugs – is acted upon.

six minute transfer

in a computer simulation, the pair found bacteria that had flagella took about 6 minutes to traverse a distance of 1 millimetre from a transmitting to a receiving nanobot. they used an encoding scheme that enabled them to encode up to 300,000 dna base pairs – or 600 kilobits of information.

"that's a bandwidth of 1.7 kilobits per second. it's not high, but for the biomedical applications we envisage it should be [fast] enough," llatser says.

others need convincing, however. "these are just simulation results. everything is possible in simulation," says andrew adamatzky of the unconventional computing department at the university of the west of england in bristol, uk.

like the barcelona team, adamatzky also uses biology to model networks. he studies how slime moulds can be used in route planning and has famously remapped the uk's and mexico's road networks with the organism physarum polycephalum.

"while their simulation results seem ok, only experimental evidence will convince me that their technique is working," says adamatzky.
(enlarge111, 19.11.2010 21:12)
loading... #25359782 * :o :( /msj ?

özet geç bin
(ayakkabi45, 19.11.2010 21:13)
loading... #25359879 * :o :( /msj ?

hubble's heir, the james webb space telescope, isn't even off the ground, but its soaring costs are casting ominous shadows over other nasa projects.

jwst will have a foldable 6.5-metre mirror to peer back to the very first galaxies. but the ambitious mission is both behind schedule and over budget.

now, an independent panel estimates the telescope will cost $1.5 billion more than its already huge $5 billion price tag and will launch at least a year after its planned 2014 lift-off.

to launch in 2015, the panel reckons the project will need an extra $500 million over the next two years, and nasa admits congress is unlikely to cough up extra cash.

instead, funding might be siphoned from proposed projects such as the wide-field infrared survey telescope, a $1.6 billion mission to study dark energy and exoplanets that recently topped astronomers' wish list for space missions in the next decade.

debra elmegreen, president of the american astronomical society, says the good news is that nasa has decided to pull jwst out of the agency's astrophysics division, where it now eats up about 40 per cent of the budget.

instead, jwst will be its own division, allowing it to draw funding from multiple sources within the agency. "there simply isn't enough money [in astrophysics], and if they try to fill it from there, it will kill astronomy," she says.
(enlarge111, 19.11.2010 21:13)
loading... #25359891 * :o :( /msj ?

hepsini okudum güzel çalışma olmuş
(guizaninbabasi, 19.11.2010 21:13)
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@3 yakala şükelana özet geç bin deyin bana
(enlarge111, 19.11.2010 21:13)
loading... #25359967 * :o :( /msj ?

injecting bacteria into the bloodstream might sound like a health risk, but those propelled by a whirling helical tail, or flagellum, could one day be used to send messages between cancer-fighting nanobots.

maria gregori and ignacio llatser at the polytechnic university of catalonia in barcelona, spain, envision a future in which nanobots in the body sense tumour cells and release anticancer drugs to fight them. but one machine can't defeat a tumour single-handedly; it needs some way of telling the others to swarm on the target.

radio signals won't travel through a liquid, and chemical forms of communication using pheromones or calcium ions work only across large or microscopic distances. on the scale of a few millimetres – the distance from one blood vessel to another – there is no way to transmit information reliably.

so the pair came up with the idea of using bacteria with flagella, in this case a non-pathogenic strain of e. coli, to send the information. the idea is to encode a message in a dna sequence that is inserted into each bacterium's cytoplasm. each nanobot would contain bacteria inscribed with every message that could be needed

when a nanobot encounters a tumour, it would release the correctly encoded bacteria. these would then swim towards other nanobots, attracted by the nutrients stored there. once there, the encoded dna sequence binds with chemical receptors and its message – telling it where to swarm or to release its drugs – is acted upon.

six minute transfer

in a computer simulation, the pair found bacteria that had flagella took about 6 minutes to traverse a distance of 1 millimetre from a transmitting to a receiving nanobot. they used an encoding scheme that enabled them to encode up to 300,000 dna base pairs – or 600 kilobits of information.

"that's a bandwidth of 1.7 kilobits per second. it's not high, but for the biomedical applications we envisage it should be [fast] enough," llatser says.

others need convincing, however. "these are just simulation results. everything is possible in simulation," says andrew adamatzky of the unconventional computing department at the university of the west of england in bristol, uk.

like the barcelona team, adamatzky also uses biology to model networks. he studies how slime moulds can be used in route planning and has famously remapped the uk's and mexico's road networks with the organism physarum polycephalum.

"while their simulation results seem ok, only experimental evidence will convince me that their technique is working," says adamatzky.