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Offline neilep

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What makes Mars magnetic?
EUROPEAN SCIENCE FOUNDATION NEWS RELEASE
Posted: August 22, 2007

*This'll interest some geologists, I think one or two may frequent the site*

Earth's surface is a very active place; its plates are forever jiggling around, rearranging themselves into new configurations. Continents collide and mountains arise, oceans slide beneath continents and volcanoes spew. As far as we know Earth's restless surface is unique to the planets in our solar system. So what is it that keeps Earth's plates oiled and on the move?

Scientists think that the secret lies beneath the crust, in the slippery asthenosphere. In order for the mantle to convect and the plates to slide they require a lubricated layer. On Mars this lubrication has long since dried up, but on Earth the plates can still glide around with ease.

If you could pick up a rock from the surface of Mars, then the chances are it would be magnetic. And yet, Mars doesn't have a magnetic field coming from its core. These rocks are clinging to the signal of an ancient magnetic field, dating back billions of years, to the times when Mars had a magnetic field like Earth's.

So how have these rocks hung onto their magnetic directions and what do they tell us about Mars? Strangely, the answer to these questions might be sitting here on Earth.

Most continental rocks on Earth align their magnetic moments with the current magnetic field - they are said to have -induced' magnetism. "I consider induced rocks to have -Alzheimers'. These are the rocks that forgot where they were born and how to get home," explains Suzanne McEnroe from the Geological Survey of Norway at a European Science Foundation, EuroMinScI conference near Nice, France this year.

However, not all of Earth's continental rocks have an induced magnetization. Some rocks stubbornly refuse to swing with the latest magnetic field, and instead keep hold of the direction they were born with. These rocks are said to have a remanent magnetization.

McEnroe and her colleagues have been studying some of Earth's strongest and oldest remanent magnetic rocks, to find out why they have such good memories. Understanding these rocks may give us clues as to what kind of rocks lie on Mars.

One of their research projects (in cooperation with Phil Schmidt and David Clark at CSIRO, Australia and just published in the Journal of Geophysical Research) is on the Peculiar Knob Formation in South Australia. These rocks are around 1 billion years old and have a strong magnetic remanence, more than 30 times larger than typically found in basaltic rocks.

"This particular research evolved from looking for an economic mineral deposit," says McEnroe. The mining company had assumed that the rocks in this strongly magnetic area were holding an induced magnetic field and that there would be magnetite buried down below. However, they were puzzled when a different mineral - hematite, came out of the drill core. Had they missed their target, or were their assumptions wrong?

By studying the samples under a powerful microscope and modelling their magnetic properties, McEnroe was able to show that the hematite was responsible for the strong magnetic field and that it was holding a remanent field from around 1 billion years ago. "We could see that the hematite contained small intergrowths that carried the magnetism," says McEnroe, who presented her findings at the 1st EuroMinScI Conference near Nice, France in March this year.

And it turns out that the microstructure of the rock is the key to whether it can hold a remanent magnetization or not. Together with Richard Harrison, a mineral physicist at Cambridge University, UK, and Peter Robinson at NGU, McEnroe has been studying strong remanent magnetic rocks from a variety of places including Scandinavia and the USA.

A study on nearly billion-year-old rocks in Norway showed a remanent magnetic anomaly comparable in scale to those observed on Mars.  The remanent magnetic anomaly dominates the local magnetic field to such a degree that more than half the Earth's field is cancelled.  It is nearly impossible to use a compass in the area, which cannot point correctly north because of the strong remanent magnetization in the rocks.

What they have found is that rocks containing nanometre scale intergrowths of ilmenite and hematite are better able to cling onto their original magnetization than those without such fine-scale features. "Placing a nanoparticle of ilmenite into the hematite host creates a strong and stable magnetic signal that can survive large changes in temperature and magnetic field over billions of years," explains Harrison.

So can this tell us anything about the rocks on Mars? "These rocks are good analogues for the magnetic rocks we see on Mars because of their strong magnetism and the length of time they have retained this memory," says McEnroe. Certainly this nano-scale microstructure is a plausible candidate for the magnetic rocks on Mars.

However, the rocks on Earth can't answer all our questions. "There is not going to be one mineral or one tectonic setting on Mars. There are going to be different reasons that enhance the signature in different places," says McEnroe. The only way to definitively answer the question is to go and pick up some rocks from Mars. 


SOURCE:SPACEFLIGHTNOW.COM
« Last Edit: 23/08/2007 19:41:52 by neilep »
 

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Astronomers spot brightest galaxies in distant universe
CENTER FOR ASTROPHYSICS NEWS RELEASE
Posted: August 22, 2007

CAMBRIDGE, MA - By combining the capabilities of several telescopes, astronomers have spotted extremely bright galaxies hiding in the distant, young universe. The newfound galaxies are intrinsically bright due to their large rate of star formation-1000 times greater than the Milky Way. However, much of that light is hidden by surrounding dust and gas, leaking out only in the infrared.

The galaxies are located about 12 billion light-years away, and existed when the universe was less than 2 billion years old. They are the most luminous and massive galaxies seen at that great distance. Smaller, dimmer galaxies were much more common in the early universe because it takes time for galaxies to form and grow.

"It's a real surprise to find galaxies that massive and luminous existing so early in the universe," said astronomer Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics (CfA). "We are witnessing the moment when the most massive galaxies in the universe were forming most of their stars in their early youth."

"It's tough to explain how such bright, massive, dusty galaxies formed so early in the lifetime of the universe," added Harvard graduate student Josh Younger.

The hide-and-seek galaxies initially were spotted with the AzTEC imaging camera on the James Clerk Maxwell Telescope. The camera, developed by a team led by Grant Wilson and Min Yun of the University of Massachusetts at Amherst, discovered several hundred previously unseen galaxies that were bright at millimeter and submillimeter wavelengths.

A team of astronomers made follow-up observations of the seven brightest galaxies in an area of the sky studied by the Cosmic Evolution Survey (COSMOS). The Smithsonian's Submillimeter Array pinpointed the exact location of each galaxy, allowing the team to confirm that the source was a single galaxy and not a blend of several fainter galaxies.

Once precise locations were known, additional observations were made with the Hubble Space Telescope, the Spitzer Space Telescope, and the Very Large Array of radio telescopes. Even Hubble's powerful vision did not detect the galaxies, confirming that they are shrouded in dust that blocks visible light. Spitzer could penetrate the dust and detect the stars directly. The Very Large Array detected only the two closest galaxies.

By combining these measurements, the astronomers showed that five of the seven AzTEC galaxies are located at redshifts greater than 3, which corresponds to a distance of 12 billion light-years.

"These results suggest that the brightest submillimeter galaxies may be the most distant," said Fazio.

The galaxies' large infrared brightness indicates that they are forming new stars rapidly, probably due to collisions and mergers.

"The source of the infrared radiation seems to be very compact, which suggests that they are colliding galaxies that may eventually evolve into quasars," said Younger.

In the future, the astronomers plan to image more sources of submillimeter radiation in different cosmic environments, to try to better understand the population.

"We also plan to use the most extended configuration of the SMA to zoom in and try to resolve these objects, and really narrow down the source of their extreme infrared luminosity," added Younger.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe

SOURCE:SPACEFLIGHTNOW.COM
 

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We have developed several devices for positioning organic molecules, molecular aggregates, cells, and single-cell organisms onto solid supports. These printers can create stable, functional protein arrays using an inexpensive technology. The cell printer allows us to create cell libraries as well as cellular assemblies that mimic their respective position in organs. The printers are derived from commercially available ink-jet printers that are modified to dispense protein or cell solutions instead of ink. We describe here the modifications to the print heads, and the printer hardware and software that enabled us to adapt the ink-jet printers for the manufacture of cell and protein arrays. The printers have the advantage of being fully automated and computer controlled, and allow for the high-throughput manufacture of protein and cell arrays.

http://www.citeulike.org/user/rodney/article/1567867

bubble jet printers are also being used to make batteries that are...er, paper thin.
 

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Gamma-ray lighthouse at the edge of our universe
EUROPEAN SPACE AGENCY NEWS RELEASE


There is a gamma-ray lighthouse shining from the edge of our universe. Astronomers have discovered it using the European Space Agency's orbiting gamma-ray observatory, Integral. Now, they must work hard to understand it.

The object, known only by its catalogue name IGR J22517+2218, was discovered this year, but its nature was unknown. This is not an unusual situation. Around 30% of the sources discovered by Integral remain unidentified so far. All astronomers know for certain, is that there are celestial sources out there, pumping gamma rays into space. However, the identification of the sources with individual celestial objects will have to wait for more detailed observations in other wavelengths.

In fact, this was the case for IGR J22517+2218. It came as a surprise when NASA's Swift satellite recorded the object in X-rays, giving its position within much more precision than can be achieved in gamma-rays. IGR J22517+2218 was identified with the already known active galaxy MG3 J225155+2217. This galaxy is so distant that it is the furthest celestial object ever to be recorded by Integral.

All active galaxies are powered by supermassive black holes. These celestial monsters contain between a million and several thousand million times the mass of the Sun.

They generate a gravitational field so large that they swallow any matter passing nearby, releasing enormous amounts of energy in the process. In the case of IGR J22517+2218, the Integral observations show that it is a gargantuan powerhouse, throwing out stupendous quantities of gamma rays.

"It is gobbling up an entire solar system every few days and hurling the energy out in gamma-rays," says Loredana Bassani, IASF-Bologna/INAF, Italy, who together with colleagues has investigated this distant galaxy.

The Integral observations show that the galaxy is one of a special kind of active galaxy, known as a blazar. These are the most energetic of the active galaxies. However, the Integral data does show some curiosities.

"This is a very peculiar object. We have been able to classify it as a blazar but it has some strange characteristics," says Bassani.

Blazars tend to have two major peaks of emission. In objects similar to IGR J22517+2218, one peak occurs in infrared wavelengths and is produced by the radiation given off by electrons spiralling around the magnetic field lines. The other peak occurs at high-energy gamma-ray wavelengths and is produced by those same electrons colliding with photons of light.

In the case of IGR J22517+2218, the object appears to have only one peak. This occurs in neither of the conventional wavelength ranges but, in fact, in the low-energy gamma-ray band instead. Either the infrared peak has been moved up in energy, or the high-energy gamma-ray peak has been moved down.

Either way, when the team can work out what this means, it will doubtlessly tell them a lot about active galaxies, and blazars in particular. "Whatever we discover, this object will stretch our understanding of the blazars," says Bassani.

The team hope to continue observing this object at all wavelengths in an effort to build up a full picture of the radiation given out by this celestial object. In this way, they will be able to piece together the manner in which the supermassive black hole at the heart of IGR J22517+2218 is devouring its surroundings.   


Source: SPACEFLIGHTNOW.COM
 

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Patients should ask surgeons about using honey to heal wounds

Surgeons are being advised to consider the supermarket as well as the drugs cupboard when it comes to effective wound healing, according to a research review published in the October issue of IJCP, the International Journal of Clinical Practice.

And patients who’ve undergone surgery should ask their doctors whether they should apply honey to their wounds to speed up healing and reduce infection.

“Honey is one of the oldest foods in existence and was an ancient remedy for wound healing” explains lead author Dr Fasal Rauf Khan from North West Wales NHS Trust in Bangor. “It was found in the tomb of King Tutankhamun and was still edible as it never spoils.”

Honey is enjoying a revival as more reports of its effectiveness are published, he adds.

“Researchers started to document the wound healing properties of honey in the early 20th century, but the introduction of antibiotics in 1940 temporarily halted its use.

“Now concerns about antibiotic resistance, and a renewed interest in natural remedies, has prompted a resurgence in the antimicrobial and wound healing properties of honey.

“Honey has a number of properties that make it effective against bacterial growth, including its high sugar content, low moisture content, gluconic acid – which creates an acidic environment – and hydrogen peroxide. It has also been shown to reduce inflammation and swelling.”

Researchers have also reported that applying honey can be used to reduce amputation rates among diabetes patients.

Stressing that patients should always check with their surgeon before applying any substance to post-operative wounds, Dr Khan adds that studies have found that honey offers a number of benefits.

“It can be used to sterilise infected wounds, speed up healing and impede tumours, particularly in keyhole surgery.”

Studies have suggested that honey should be applied at regular intervals, from hourly to twice daily and that wounds can become sterile in three to 10 days.

“The research suggests that honey seems to be especially indicated when wounds become infected or fail to close or heal” says Dr Khan. “It is probably even more useful for healing the wounds left by laparoscopic surgery to remove cancers.”

18 studies covering more than 60 years were included in the review. The authors also looked at other substances used for wound healing, including maggots, which were also commonly used before the introduction of antibiotics and are enjoying a revival.

The team also discovered an ancient manuscript that used wine dregs, juniper prunes and beer, but point out that that has not been tried and tested in recent years!

“Our research suggests that surgeons should seriously consider using honey for post-operative wounds and offer this to patients” concludes Dr Khan. “We would also encourage patients to ask about honey as an option, but stress that they should always follow their surgeon’s advice and not try any home remedies.”

SOURCE: EUREKALERT.ORG
 

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Dwarf galaxies need dark matter too, U-M astronomers say

ANN ARBOR, Mich.—Stars in dwarf spheroidal galaxies behave in a way that suggests the galaxies are utterly dominated by dark matter, University of Michigan astronomers have found.

Astronomy professor Mario Mateo and post-doctoral researcher Matthew Walker measured the velocity of 6,804 stars in seven dwarf satellite galaxies of the Milky Way: Carina, Draco, Fornax, Leo I, Leo II, Sculptor and Sextans. They found that, contrary to what Newton's law of gravity predicts, stars in these galaxies do not move slower the farther they are from their galaxy's core.

"These galaxies show a problem right from the center," Mateo said. "The velocity doesn't get smaller. It just stays the same, which is eerie."

Astronomers already know stars in spiral galaxies behave in a similar way. This research dramatically increases the available information about smaller galaxies, making it possible to confirm that the distribution of light and stars in them is not the same as the distribution of mass.

"We have more than doubled the amount of data having to do with these galaxies, and that allows us to study them in an unprecedented manner. Our research shows that dwarf galaxies are utterly dominated by dark matter, so long as Newtonian gravity adequately describes these systems," Walker said. Walker received his doctorate from U-M earlier this year and currently has a post-doctoral position at the University of Cambridge in the United Kingdom.

Dark matter is a substance astronomers have not directly observed, but they deduce it exists because they detect its gravitational effects on visible matter. Based on these measurements, the prevailing theory in astronomy and cosmology is that the visible parts of the universe make up only a fraction of its total matter and energy.

The planet Neptune was once "dark matter," Mateo said. Before the term was even coined, astronomers predicted its existence based on an anomaly in the orbit of Neptune's neighbor Uranus. They knew just where to look for Neptune.

For the past quarter century, astronomers have been looking for the Neptune of the universe, so to speak. Dark matter could take the form of dwarf stars and planets, elementary particles including neutrinos, or hypothetical and as-yet undetected particles that don't interact with visible light or other parts of the electromagnetic spectrum.

Dark matter is believed to hold galaxies together. The gravitational force of the visible matter is not considered strong enough to prevent stars from escaping. Other theories exist to explain these discrepancies, though. For example, Modified Newtonian Dynamics, Mateo said, proposes that gravitational forces become stronger when accelerations are very weak. While their results align with current dark matter models, Mateo and Walker say they also bolster this less-popular explanation.

"These dwarf galaxies are not much to look at," Mateo continued, "but they may really alter our fundamental views on the nature of dark matter and, perhaps, even gravity."

Walker will present a paper on these findings on Oct. 30 at the Magellan Science Meeting in Cambridge, Mass. The paper he will present is Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies. It was published in the Sept. 20 edition of Astrophysical Journal Letters.

SOURCE: University of Michigan News Service http://www.ns.umich.edu
 

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Scientist brings 50 million year old spider 'back to life'

A 50-million-year-old fossilised spider has been brought back to life in stunning 3D by a scientist at The University of Manchester.

In a paper published in the latest issue of the Zootaxa journal, Dr David Penney and co-authors from Ghent University in Belgium report on the use of a technique called ‘Very High Resolution X-Ray Computed Tomography’ (VHR-CT) to ‘digitally dissect’ tiny fossils and reveal the preservation of internal organs.

Dr Penney, from The School of Earth, Atmospheric and Environmental Sciences (SEAES), specialises in studying spiders trapped and preserved in amber tens of millions of years ago.

The male spider studied in his latest paper is a new species named Cenotextricella simoni. It is around 53-million years old and was found preserved in amber in an area of France known as the Paris Basin.

This is the first time the VHR-CT technique has been used to digitally dissect a fossil in amber – and Dr Penney says it has the potential to ‘revolutionise’ their study.

The VHR-CT technique was originally developed for medical diagnostic purposes.

Dr Penney said: “This technique essentially generates full 3D reconstructions of minute fossils and permits digital dissection of the specimen to reveal the preservation of internal organs.

“Up until recently the only place to do such scans was at The University of Texas, although they never achieved results like these.

“My colleagues in the department of Subatomic and Radiation Physics at Ghent University in Belgium have significantly increased the resolution of the technology, bringing some quite amazing results.

“This is definitely the way forward for the study of amber fossils.

“Amber provides a unique window into past forest ecosystems. It retains an incredible amount of information, not just about the spiders themselves, but also about the environment in which they lived.”

Dr Penney is currently spending an indefinite period in the African jungle in a ‘living laboratory' studying spiders.

Earlier this year, a species of spider which dates back more than 20 million years was named after Dr Penney. The amber-encased spider which was discovered deep in a Mexican mine is thought to have lived long before the first humans.

It was found by a Mexican researcher who earned the right to name the species and he chose the name ‘Episinus penneyi’ in honour of his former colleague.

SOURCE: www.eurekalert.org

 

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A new window on the universe
UWM physicists involved in international project to scour space for gravitational waves

UWM physicists who are working on the international LIGO project are (clockwise from left) Xavier Siemens, Alan Wiseman, Patrick Brady and Jolien Creighton. All four faculty members came to UWM...
Click here for more information.

Using new tools to look at the universe, says Patrick Brady, often has led to discoveries that change the course of science. History is full of examples.

“Galileo was the first person to use the telescope to view the cosmos,” says Brady, a UWM professor of physics. “His observations with the new technology led to the discovery of moons orbiting Jupiter and lent support to the heliocentric model of the solar system.”

Just such an opportunity exists today with a unique observatory that is scanning the skies, searching for one of Einstein’s greatest predictions – gravitational waves.

Gravitational waves are produced when massive objects in space move violently. The waves carry the imprint of the events that cause them. Scientists already have indirect evidence that gravitational waves exist, but have not directly detected them.

UWM researchers, backed by considerable funding from the National Science Foundation, are taking a leadership role in the quest.

It is an epic undertaking involving about 500 scientists worldwide, including Brady and other members of UWM’s Center for Cosmology and Gravitation: associate professors Alan Wiseman and Jolien Creighton, and assistant professor Xavier Siemens.

Two UWM adjunct physicists, who work at the Max Planck Institute in Germany, also are involved – former UWM professor Bruce Allen and scientist Maria Alessandra Papa.

“It’s an unimaginable opportunity to be on the forefront of scientific discovery,” says Creighton.

The Laser Interferometer Gravitational-wave Observatory, or LIGO, consists of detectors at two U.S. sites managed by the California Institute of Technology (Caltech) and Massachusetts Institute of Technology (MIT).

UWM’s physicists are analyzing the data generated by the LIGO facilities.

The project is supported with a sizable investment of grant money from both federal and UWM sources.

Last year, UWM’s LIGO group brought in $3 million in grant funding. Since 1999, UWM has received more than $9 million for the project, with much of it going toward a supercomputer called Nemo that operates unobtrusively on the second floor of the Physics Building.

Stretching and squeezing

The LIGO observatories use lasers to accurately monitor the distance between a central station and mirrors suspended three miles away along perpendicular arms. When a gravitational wave, a traveling ripple in space-time, passes by, the mirror in one arm will move closer to the central station, while the other mirror will move away.

The change in distance caused by stretching and squeezing is what LIGO is designed to measure, says Wiseman.

Those changes will be inconceivably tiny. LIGO can record distortions at a scale so small, it is comparable in distance to a thousandth of the size of an atomic nucleus.

LIGO records a series of numbers – lots of them – and feeds them to several supercomputer clusters around the country, including UWM’s Nemo cluster.

Think of a modern hard disk on a desktop computer, which stores about 100 gigabytes. LIGO fills up about 10 of those at Nemo in a single day, says Brady.

The computer’s job is to sort out the numerical patterns representing gravitational waves buried in ambient noise produced by lots of other vibrations – from internal vibrations of the equipment itself, to magnetic fluctuations from lightning storms, to seismic vibrations from trains rolling along the tracks a few miles from the observatory, or from earthquakes on the other side of the world.

“There are thousands or even millions of different signals that could be emitted from space,” says Wiseman. “So you have to take each segment of data individually. That turns out to be a formidable computational problem.”

Nemo performs many billions of calculations per second in its search for these signals.

Space sounds


The strings of numbers from LIGO are like tracks on a compact disk, says Brady. That means, once detected, gravitational-wave signals can be converted into sound.

In fact, scientists have already simulated, based on mathematical predictions, what certain events in space will sound like.

When two black holes are merging, for example, you might expect to hear a “chirp” that represents the spiraling together of the black holes just before they collide. “The spiral can go on for tens of thousands of years,” says Brady. “The sound is the identifying signal of the last few seconds of the process!”

Those analyzing the data from space could actually listen to the data. Instead, scientists look for the signals using computers like Nemo.

To augment the computing capacity, UWM is hosting a way for anyone with a computer and a high-speed Internet connection to join the astrophysical treasure hunt. Called “Einstein@Home, the program borrows computer power available when participants are not using it, and pool those resources to aid in filtering the massive amounts of data from LIGO.

Possible secrets


Scientists concede that the current LIGO facilities will need to be improved to increase the chances of detecting gravitational waves. More NSF funding to do that is requested in the 2009 U.S. budget currently winding its way through the approval process.

For now, the best hope is to detect events relatively close to Earth.

So what is the likelihood of success"

“The events we are looking for may only happen once every million years in our galaxy,” says Wiseman, “but if your instrument is sensitive enough to see such events in, say, one million galaxies, then the probability of detecting something is much larger.”

Gravitational waves may hold secrets to the nature of black holes, the unknown properties of nuclear material, and maybe even how the universe began.

“We’ve only been able to find out about the universe since it became cool,” says Siemens. “But with gravitational waves, we’ll see the universe when it was much younger – and hotter.”

But then again, scientists don’t really know.

“I think we’re in for a surprise,” says Siemens. “We have all these ideas about what we think we will find, but it could be something completely different.”
 

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Saturn's rings may be old as solar system, Cassini shows
UNIVERSITY OF COLORADO NEWS RELEASE
Posted: December 12, 2007

New observations by NASA's Cassini spacecraft indicate the rings of Saturn, once thought to have formed during the age of the dinosaurs, instead may have been created roughly 4.5 billion years ago when the solar system was still under construction.



 
Professor Larry Esposito, principal investigator for Cassini's Ultraviolet Imaging Spectrograph at CU-Boulder, said data from NASA's Voyager spacecraft in the 1970s and later NASA's Hubble Space Telescope had led scientists to believe Saturn's rings were relatively youthful and likely created by a comet that shattered a large moon, perhaps 100 million years ago.

But ring features seen by instruments on Cassini -- which arrived at Saturn in 2004 -- indicate the rings were not formed by a single cataclysmic event, he said. The ages of the different rings appear to vary significantly and the ring material is continually being recycled, Esposito said.

"The evidence is consistent with the picture that Saturn has had rings all through its history," said Esposito of CU-Boulder's Laboratory for Atmospheric and Space Physics. "We see extensive, rapid recycling of ring material, in which moons are continually shattered into ring particles, which then gather together and re-form moons."

Esposito and CU-Boulder colleague Miodrag Sremcevic presented their findings today in a news briefing at the fall meeting of the American Geophysical Union held Dec. 10 to Dec. 14 in San Francisco.

"We have discovered that the rings were probably not created just yesterday in cosmic time, and in this scenario it is not just luck that we are seeing planetary rings now," said Esposito. "They probably were always around but continually changing, and they will be around for many billions of years."

Scientists had previously believed rings as old as Saturn itself should be darker due to ongoing pollution by the "infall" of meteoric dust, leaving telltale spectral signatures, Esposito said. But the new Cassini observations indicate the churning mass of ice and rock within Saturn's gigantic ring system is likely much larger than previously estimated, helping to explain why the rings appear relatively bright to ground-based telescopes and spacecraft.

"The more mass there is in the rings, the more raw material there is for recycling, which essentially spreads this cosmic pollution around," he said. "If this pollution is being shared by a much larger volume of ring material, it becomes diluted and helps explain why the rings appear brighter and more pristine than we would have expected."

Esposito, who discovered Saturn's faint F ring in 1979 using data from NASA's Pioneer 11 spacecraft, said an upcoming paper by him and colleagues in the journal Icarus supports the theory that Saturn's ring material is being continually recycled. Observing the flickering of starlight passing through the rings in a process known as stellar occultation, the researchers discovered 13 objects in the F ring ranging in size from 30 yards to six miles across.

Since most of the objects were translucent -- indicating at least some starlight was passing through them -- the researchers concluded they probably are temporary clumps of icy boulders that are continually collecting and disbanding due to the competing processes of shattering and coming together again. The team tagged the clumpy moonlets with cat names like "Mittens" and "Fluffy" because they appear to come and go unexpectedly over time and have multiple lives, said Esposito.

Esposito stressed that in the future Saturn's rings won't be the same we see today, likening them to great cities around the world like San Francisco, Berlin or Beijing. "While the cities themselves will go on for centuries or millennia, the faces of people on the streets will always be changing due to continual birth and aging of new citizens."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington, D.C.

SOURCE: SPACFLIGHTNOW.ORG
 

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Are humans evolving faster?

Findings suggest we are becoming more different, not alike
Researchers discovered genetic evidence that human evolution is speeding up – and has not halted or proceeded at a constant rate, as had been thought – indicating that humans on different continents are becoming increasingly different.

“We used a new genomic technology to show that humans are evolving rapidly, and that the pace of change has accelerated a lot in the last 40,000 years, especially since the end of the Ice Age roughly 10,000 years ago,” says research team leader Henry Harpending, a distinguished professor of anthropology at the University of Utah.

Harpending says there are provocative implications from the study, published online Monday, Dec. 10 in the journal Proceedings of the National Academy of Sciences:

-- “We aren’t the same as people even 1,000 or 2,000 years ago,” he says, which may explain, for example, part of the difference between Viking invaders and their peaceful Swedish descendants. “The dogma has been these are cultural fluctuations, but almost any temperament trait you look at is under strong genetic influence.”

-- “Human races are evolving away from each other,” Harpending says. “Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity.” He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, “and there has not been much flow of genes between the regions since then.”

“Our study denies the widely held assumption or belief that modern humans [those who widely adopted advanced tools and art] appeared 40,000 years ago, have not changed since and that we are all pretty much the same. We show that humans are changing relatively rapidly on a scale of centuries to millennia, and that these changes are different in different continental groups.”

The increase in human population from millions to billions in the last 10,000 years accelerated the rate of evolution because “we were in new environments to which we needed to adapt,” Harpending adds. “And with a larger population, more mutations occurred.”

Study co-author Gregory M. Cochran says: “History looks more and more like a science fiction novel in which mutants repeatedly arose and displaced normal humans – sometimes quietly, by surviving starvation and disease better, sometimes as a conquering horde. And we are those mutants.”

Harpending conducted the study with Cochran, a New Mexico physicist, self-taught evolutionary biologist and adjunct professor of anthropology at the University of Utah; anthropologist John Hawks, a former Utah postdoctoral researcher now at the University of Wisconsin, Madison; geneticist Eric Wang of Affymetrix, Inc. in Santa Clara, Calif.; and biochemist Robert Moyzis of the University of California, Irvine.

No Justification for Discrimination

The new study comes from two of the same University of Utah scientists – Harpending and Cochran – who created a stir in 2005 when they published a study arguing that above-average intelligence in Ashkenazi Jews – those of northern European heritage – resulted from natural selection in medieval Europe, where they were pressured into jobs as financiers, traders, managers and tax collectors. Those who were smarter succeeded, grew wealthy and had bigger families to pass on their genes. Yet that intelligence also is linked to genetic diseases such as Tay-Sachs and Gaucher in Jews.

That study and others dealing with genetic differences among humans – whose DNA is more than 99 percent identical – generated fears such research will undermine the principle of human equality and justify racism and discrimination. Other critics question the quality of the science and argue culture plays a bigger role than genetics.

Harpending says genetic differences among different human populations “cannot be used to justify discrimination. Rights in the Constitution aren’t predicated on utter equality. People have rights and should have opportunities whatever their group.”

Analyzing SNPs of Evolutionary Acceleration

The study looked for genetic evidence of natural selection – the evolution of favorable gene mutations – during the past 80,000 years by analyzing DNA from 270 individuals in the International HapMap Project, an effort to identify variations in human genes that cause disease and can serve as targets for new medicines.

The new study looked specifically at genetic variations called “single nucleotide polymorphisms,” or SNPs (pronounced “snips”) which are single-point mutations in chromosomes that are spreading through a significant proportion of the population.

Imagine walking along two chromosomes – the same chromosome from two different people. Chromosomes are made of DNA, a twisting, ladder-like structure in which each rung is made of a “base pair” of amino acids, either G-C or A-T. Harpending says that about every 1,000 base pairs, there will be a difference between the two chromosomes. That is known as a SNP.

Data examined in the study included 3.9 million SNPs from the 270 people in four populations: Han Chinese, Japanese, Africa’s Yoruba tribe and northern Europeans, represented largely by data from Utah Mormons, says Harpending.

Over time, chromosomes randomly break and recombine to create new versions or variants of the chromosome. “If a favorable mutation appears, then the number of copies of that chromosome will increase rapidly” in the population because people with the mutation are more likely to survive and reproduce, Harpending says.

“And if it increases rapidly, it becomes common in the population in a short time,” he adds.

The researchers took advantage of that to determine if genes on chromosomes had evolved recently. Humans have 23 pairs of chromosomes, with each parent providing one copy of each of the 23. If the same chromosome from numerous people has a segment with an identical pattern of SNPs, that indicates that segment of the chromosome has not broken up and recombined recently.

That means a gene on that segment of chromosome must have evolved recently and fast; if it had evolved long ago, the chromosome would have broken and recombined.

Harpending and colleagues used a computer to scan the data for chromosome segments that had identical SNP patterns and thus had not broken and recombined, meaning they evolved recently. They also calculated how recently the genes evolved.

A key finding: 7 percent of human genes are undergoing rapid, recent evolution.

The researchers built a case that human evolution has accelerated by comparing genetic data with what the data should look like if human evolution had been constant:


The study found much more genetic diversity in the SNPs than would be expected if human evolution had remained constant.


If the rate at which new genes evolve in Africans was extrapolated back to 6 million years ago when humans and chimpanzees diverged, the genetic difference between modern chimps and humans would be 160 times greater than it really is. So the evolution rate of Africans represents a recent speedup in evolution.


If evolution had been fast and constant for a long time, there should be many recently evolved genes that have spread to everyone. Yet, the study revealed many genes still becoming more frequent in the population, indicating a recent evolutionary speedup.

Next, the researchers examined the history of human population size on each continent. They found that mutation patterns seen in the genome data were consistent with the hypothesis that evolution is faster in larger populations.

Evolutionary Change and Human History: Got Milk?

“Rapid population growth has been coupled with vast changes in cultures and ecology, creating new opportunities for adaptation,” the study says. “The past 10,000 years have seen rapid skeletal and dental evolution in human populations, as well as the appearance of many new genetic responses to diet and disease.”

The researchers note that human migrations into new Eurasian environments created selective pressures favoring less skin pigmentation (so more sunlight could be absorbed by skin to make vitamin D), adaptation to cold weather and dietary changes.

Because human population grew from several million at the end of the Ice Age to 6 billion now, more favored new genes have emerged and evolution has speeded up, both globally and among continental groups of people, Harpending says.

"We have to understand genetic change in order to understand history,” he adds.

For example, in China and most of Africa, few people can digest fresh milk into adulthood. Yet in Sweden and Denmark, the gene that makes the milk-digesting enzyme lactase remains active, so “almost everyone can drink fresh milk,” explaining why dairying is more common in Europe than in the Mediterranean and Africa, Harpending says.

He now is studying if the mutation that allowed lactose tolerance spurred some of history’s great population expansions, including when speakers of Indo-European languages settled all the way from northwest India and central Asia through Persia and across Europe 4,000 to 5,000 years ago. He suspects milk drinking gave lactose-tolerant Indo-European speakers more energy, allowing them to conquer a large area.

But Harpending believes the speedup in human evolution “is a temporary state of affairs because of our new environments since the dispersal of modern humans 40,000 years ago and especially since the invention of agriculture 12,000 years ago. That changed our diet and changed our social systems. If you suddenly take hunter-gatherers and give them a diet of corn, they frequently get diabetes. We’re still adapting to that. Several new genes we see spreading through the population are involved with helping us prosper with high-carbohydrate diet.”





SOURCE : University of Utah Public Relations

www.unews.utah.edu

Via EUYREALERT.ORG





 

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Red dust in disk may harbor precursors to life
CARNEGIE INSTITUTION NEWS RELEASE
Posted: January 5, 2008

WASHINGTON, DC - Astronomers at the Carnegie Institution have found the first indications of highly complex organic molecules in the disk of red dust surrounding a distant star. The eight-million-year-old star, known as HR 4796A, is inferred to be in the late stages of planet formation, suggesting that the basic building blocks of life may be common in planetary systems.

In a study published in the current Astrophysical Journal Letters, John Debes and Alycia Weinberger of the Carnegie Institution's Department of Terrestrial Magnetism with Glenn Schneider of the University of Arizona report observations of infrared light from HR 4796A using the Near-Infrared Multi-Object Spectrometer aboard the Hubble Space Telescope. The researchers found that the spectrum of visible and infrared light scattered by the star's dust disk looks very red, the color produced by large organic carbon molecules called tholins. The spectrum does not match those of other red substances, such as iron oxide.

Tholins do not form naturally on present-day Earth because oxygen in the atmosphere would quickly destroy them, but they are hypothesized to have existed on the primitive Earth billions of years ago and may have been precursors to the biomolecules that make up living organisms. Tholins have been detected elsewhere in the solar system, such as in comets and on Saturn's moon Titan, where they give the atmosphere a red tinge. This study is the first report of tholins outside the solar system.

"Until recently it's been hard to know what makes up the dust in a disk from scattered light, so to find tholins this way represents a great leap in our understanding," says Debes.

HR 4796A is located in the constellation Centaurus, visible primarily form the southern hemisphere. It is about 220 light years from Earth. The discovery of its dust disk in 1991 generated excitement among astronomers, who consider it a prime example of a planetary system caught in the act of formation. The dust is generated by collisions of small bodies, perhaps similar to the comets or asteroids in our solar system, and which may be coated by the organics. These planetesimals can deliver these building blocks for life to any planets that may also be circling the star.

"Astronomers are just beginning to look for planets around stars much different from the Sun. HR 4796A is twice as massive, nearly twice as hot as the sun, and twenty times more luminous than the Sun," says Debes. "Studying this system provides new clues to understanding the different conditions under which planets form and, perhaps, life can evolve."

This research is based on observations with the NASA/ESA Hubble Space Telescope and was supported by NASA and the NASA Astrobiology Institute.

The Carnegie Institution has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

SOURCE:SPACEFLIGHTNOW.ORG
 

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X-rays betray giant particle accelerator in the sky
EUROPEAN SPACE AGENCY NEWS RELEASE


ESA's orbiting gamma-ray observatory, Integral, has made the first unambiguous discovery of highly energetic X-rays coming from a galaxy cluster. The find has shown the cluster to be a giant particle accelerator. 

The Ophiuchus galaxy cluster is one of brightest in the sky at X-ray wavelengths. The X-rays detected are too energetic to originate from quiescent hot gas inside the cluster and suggest instead that giant shockwaves must be rippling through the gas. This has turned the galaxy cluster into a giant particle accelerator.

Most of the X-rays come from hot gas in the cluster, which in the case of Ophiuchus is extremely hot, at 100 million degrees Kelvin. Four years ago, data from the Italian/ Dutch BeppoSAX satellite showed a possible extra component of high-energy X-rays in a different cluster, the Coma cluster.

"Two groups analysed the data. One group saw the component but the other did not," says Dominique Eckert, Integral Science Data Centre (ISDC), University of Geneva, Switzerland. So Eckert and colleagues from ISDC launched an investigation into the mystery.

They turned to Integral and its five-year, all-sky survey and found that ESA's orbiting gamma-ray observatory did show an unambiguous detection of highly energetic X-rays, coming from the Ophiuchus cluster of galaxies. These X-rays can be produced in two ways, both of which involve high-energy electrons.

The first option is that the electrons are caught in the magnetic field threading through the cluster. In this case, the electrons would spiral around the magnetic field lines, releasing synchrotron radiation in the form of X-rays.

The electrons would be extremely energetic, carrying over 100 000 times the energy of the electrons in the alternative scenario, which is that the electrons are perhaps colliding with microwaves left over from the origin of the Universe and now bathe all of space. In such collisions, the electrons lose some energy, emitted as X-rays.

Determining which of these scenarios is correct is the next job for the team. They plan to use radio telescopes to measure the magnetic field of the galaxy cluster. They also plan to use the High Energy Stereoscopic System (HESS) in Namibia. This giant telescope looks for the brief flash of light generated when highly energetic gamma rays collide with particles in Earth's atmosphere. If HESS sees such flashes coming from Ophiuchus, then the astronomers will know that the synchrotron scenario is correct.

Either way, the electrons themselves are most likely to be accelerated to high energies by shockwaves travelling through the cluster gas. The shockwaves are set up when two clusters collide and merge. The question is how recently Ophiuchus swallowed its companion cluster.

In the synchrotron scenario, the highly energetic electrons cool very quickly. If the team find this to be the case, then the collision must still be in progress. In the case of microwave scattering, cooling takes a long time and the collision could have taken place at any time in the past.

Once the scientists know, they will be able to properly understand the history of the cluster. One thing is already certain; nature has transformed the galaxy cluster into a powerful particle accelerator, perhaps 20 times more powerful than CERN's Large Hadron Collider (LHC), which begins operation in Switzerland this summer.

"Of course the Ophiuchus cluster is somewhat bigger," says Stephane Paltani, a member of the ISDC team. While LHC is 27 km across, the Ophiuchus galaxy cluster is over two million light-years in diameter."   
 

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Good luck indeed: 53 million-year-old rabbit's foot bones found

One day last spring, fossil hunter and anatomy professor Kenneth Rose, Ph.D. was displaying the bones of a jackrabbit’s foot as part of a seminar at the Johns Hopkins University School of Medicine when something about the shape of the bones looked oddly familiar.

That unanticipated eureka moment has led researchers at the school to the discovery of the oldest known record of rabbits. The fossil evidence in hand, found in west-central India, predates the oldest previously known rabbits by several million years and extends the record of the whole category of the animal on the Indian subcontinent by 35 million years.

Published online in the February Proceedings of the Royal Society, the investigators say previous fossil and molecular data suggested that rabbits and hares diverged about 35 million years ago from pikas, a mousy looking member of the family Ochotonidae in the order of lagomorphs, which also includes all of the family Leporidae encompassing rabbits and hares.

But the team led by Johns Hopkins’s Rose found that their rabbit bones were very similar in characteristics to previously unreported Chinese rabbit fossils that date to the Middle Eocene epoch, about 48 million years ago. The Indian fossils, dating from about 53 million years ago, appear to show advanced rabbit-like features, according to Rose.

“What we have suggests that diversification among the Lagamorpha group-all modern day hares, rabbits and pikas-may already have started by the Early Eocene,” says Rose, professor in the Center for Functional Anatomy and Evolution at the Johns Hopkins University School of Medicine.

Rose says the new discovery was delayed a few years because the researchers had not been looking specifically to determine the age of rabbits. “We found these bones on a dig in India a few years ago and didn’t know what animal they came from, so we held onto them and figured we’d look at them later,” he says. “It didn’t occur to us they would be rabbits because there were no known rabbits that early in time and the only known rabbits from that part of the world are from central Asia.”

But one day, while using the jackrabbit foot bones as a teaching tool for a class, the shape of the bones in the class struck him as something he’d seen before among his collection of unidentified bones.

Sure enough, the tiny bones about a quarter of an inch long from India looked remarkably similar to ankle and foot bones from modern day jackrabbits, which are 4 to 5 times bigger.

Rose and his team set out and measured every dimension of their Indian bones and compared them to eight living species of rabbits and hares. They also compared them to two species of the related pika-that mouse-like, mountain-dwelling critter that lives in the Rocky Mountains of North America, among other places.

Using a technique called character analysis, the team first recorded measurements of 20 anatomical features of the bones, which showed that the bones are definitely Lagomorph and closer to rabbits than pikas. The scientists then ran a series of statistical tests on the individual measurements to see how they compared with the Chinese fossils as well as living rabbits and pikas. They found that although the Indian fossils resemble pikas in some primitive features, they look more like rabbits in specialized bone features.

Asked how many years of good luck one gets with a 53 million-year-old rabbit foot bone, Rose quipped that he “already got lucky with the feet, but what we really would like are some teeth that tell how different these animals really were.”


SOURCE: EUREKALERT.ORG
 

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Rare cosmic rays are from far away
Study confirms 1966 prediction: The most energetic particles in the universe are not from the neighborhood

Final results from the University of Utah’s High-Resolution Fly’s Eye cosmic ray observatory show that the most energetic particles in the universe rarely reach Earth at full strength because they come from great distances, so most of them collide with radiation left over from the birth of the universe.

The findings are based on nine years of observations at the now-shuttered observatory on the U.S. Army’s Dugway Proving Ground. They confirm a 42-year-old prediction – known as the Greisen-Zatsepin-Kuzmin (GZK) “cutoff,” “limit” or “suppression” – about the behavior of ultrahigh-energy cosmic rays, which carry more energy than any other known particle.

The idea is that most – but not all – cosmic ray particles with energies above the GZK cutoff cannot reach Earth because they lose energy when they collide with “cosmic microwave background radiation,” which was discovered in 1965 and is the “afterglow” of the “big bang” physicists believe formed the universe 13 billion years ago.

The journal Physical Review Letters published the results Friday, March 21.

The GZK limit’s existence was first predicted by Kenneth Greisen of Cornell University while visiting the University of Utah in 1966, and independently by Georgiy Zatsepin and Vadim Kuzmin of Moscow’s Lebedev Institute of Physics.

“It has been the goal of much of ultrahigh-energy cosmic ray physics for the past 40 years to find this cutoff or disprove it,” says physics Professor Pierre Sokolsky, dean of the University of Utah College of Science and leader of the study by a collaboration of 60 scientists from seven research institutions. “For the first time in 40 years, that question is answered: there is a cutoff.”

That conclusion, based on 1997-early 2006 observations at the High Resolution Fly’s Eye cosmic ray observatory (nicknamed HiRes) in Utah’s western desert, has been bolstered by the new Auger cosmic ray observatory in Argentina. During a cosmic ray conference in Merida, Mexico, last summer, Auger physicists outlined preliminary, unpublished results showing that the number of ultrahigh-energy cosmic rays reaching Earth drops sharply above the cutoff.

So both the HiRes and Auger findings contradict Japan’s now-defunct Akeno Giant Air Shower Array (AGASA), which observed roughly 10 times more of the highest-energy cosmic rays – and thus suggested there was no GZK cutoff.

Cosmic Rays: Far Out

Last November, the Auger observatory collaboration – to which Sokolsky also belongs – published a study suggesting that the highest-energy cosmic rays come from active galactic nuclei or AGNs, or the hearts of extremely active galaxies believed to harbor supermassive black holes.

AGNs are distributed throughout the universe, so confirmation that the GZK cutoff is real suggests that if ultrahigh-energy cosmic rays are spewed out by AGNs, they primarily are very distant from the Earth – at least in Northern Hemisphere skies viewed by the HiRes observatory. University of Utah physics Professor Charlie Jui, a co-author of the new study, says that means galaxies beyond our “local” supercluster of galaxies at distances of at least 150 million light years from Earth, or roughly 870 billion billion miles. [In U.S. usage, billion billion is correct here and in subsequent references for 10 to the 18th power. In British usage, 10 to the 18th power should be million billion.]

However, unpublished results from HiRes do not find the same correlation that Auger did between ultrahigh-energy cosmic rays and active galactic nuclei. So there still is uncertainty about the true source of extremely energetic cosmic rays.

“We still don’t know where they’re coming from, but they’re coming from far away,” Sokolsky says. “Now that we know the GZK cutoff is there, we have to look at sources much farther out.”

In addition to the University of Utah, High Resolution Fly’s Eye scientists are from Los Alamos National Laboratory in New Mexico, Columbia University in New York, Rutgers University – the State University of New Jersey, Montana State University in Bozeman, the University of Tokyo and the University of New Mexico, Albuquerque.

Messengers from the Great Beyond

Cosmic rays, discovered in 1912, are subatomic particles: the nuclei of mostly hydrogen (bare protons) and helium, but also of some heavier elements such as oxygen, carbon, nitrogen or even iron. The sun and other stars emit relatively low-energy cosmic rays, while medium-energy cosmic rays come from exploding stars.

The source of ultrahigh-energy cosmic rays has been a mystery for almost a century. The recent Auger observatory results have given the edge to the popular theory they originate from active galactic nuclei. They are 100 million times more energetic than anything produced by particle smashers on Earth. The energy of one such subatomic particle has been compared with that of a lead brick dropped on a foot or a fast-pitched baseball hitting the head.

“Quite apart from arcane physics, we are talking about understanding the origin of the most energetic particles produced by the most energetic acceleration process in the universe,” Sokolsky says. “It’s a question of how much energy the universe can pack into these extraordinarily tiny particles known as cosmic rays. … How high the energy can be in principle is unknown. By the time they get to us, they have lost that energy.”

He adds: “Looking at energy processes at the very edge of what’s possible in the universe is going to tell us how well we understand nature.”

Ultrahigh-energy cosmic rays are considered to be those above about 1 billion billion electron volts (1 times 10 to the 18th power).

The most energetic cosmic ray ever found was detected over Utah in 1991 and carried an energy of 300 billion billion electron volts (3 times 10 to the 20th power). It was detected by the University of Utah’s original Fly’s Eye observatory, which was built at Dugway during 1980-1981 and improved in 1986. A better observatory was constructed during 1994-1999 and named the High Resolution Fly’s Eye.

Jui says that during its years of operation, HiRes detected only four of the highest-energy cosmic rays – those with energies above 100 billion billion electron volts. AGASA detected 11, even though it was only one-fourth as sensitive as HiRes.

The new study covers HiRes operations during 1997 through 2006, and cosmic rays above the GZK cutoff of 60 billion billion electron volts (6 times 10 to the 19th power). During that period, the observatory detected 13 such cosmic rays, compared with 43 that would be expected without the cutoff. So the detection of only 13 indicates the GZK limit is real, and that most ultrahigh-energy cosmic rays are blocked by cosmic microwave background radiation so that few reach Earth without losing energy.

The discrepancy between HiRes Fly’s Eye and AGASA is thought to stem from their different methods for measuring cosmic rays.

HiRes used multifaceted (like a fly’s eye) sets of mirrors and photomultiplier tubes to detect faint ultraviolet fluorescent flashes in the sky generated when incoming cosmic ray particles hit Earth’s atmosphere. Sokolsky and University of Utah physicist George Cassiday won the prestigious 2008 Panofsky Prize for developing the method.

HiRes measured a cosmic ray’s energy and direction more directly and reliably than AGASA, which used a grid-like array of “scintillation counters” on the ground.

The Search Goes On

University of Tokyo, University of Utah and other scientists now are using the new $17 million Telescope Array cosmic ray observatory west of Delta, Utah, which includes three sets of fluorescence detectors and 512 table-like scintillation detectors spread over 400 square miles – in other words, the two methods that produced conflicting results at HiRes and AGASA. One goal is to figure out why ground detectors gave an inflated count of the number of ultrahigh-energy cosmic rays.

The Telescope Array also will try to explain an apparent shortage in the number of cosmic rays at energies about 10 times lower than the GZK cutoff. This ankle-shaped dip in the cosmic ray spectrum is a deficit of cosmic rays at energies of about 5 billion billion electron volts.

Sokolsky says there is debate over whether the “ankle” represents cosmic rays that run out of “oomph” after being spewed by exploding stars in our galaxy, or the loss of energy predicted to occur when ultrahigh-energy cosmic rays from outside our galaxy collide with the big bang’s afterglow, generating electrons and antimatter positrons.

The Telescope Array and Auger observatories will keep looking for the source of rare ultrahigh-energy cosmic rays that evade the big bang afterglow and reach Earth.

“The most reasonable assumption is they are coming from a class of active galactic nuclei called blazars,” Sokolsky says.

Such a galaxy center is suspected to harbor a supermassive black hole with the mass of a billion or so suns. As matter is sucked into the black hole, nearby matter is spewed outward in the form of a beam-like jet. When such a jet is pointed at Earth, the galaxy is known as a blazar.

“It’s like looking down the barrel of a gun,” Sokolsky says. “Those guys are the most likely candidates for the source of ultrahigh-energy cosmic rays.”

SOURCE:EUREKALERT.ORG
 

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NASA finds mini-black hole

If you want to know the universe’s ultimate tough guys, look no further than black holes. These strange objects gobble up gas from their surroundings, and sometimes swallow entire stars. But a black hole’s gravity is so powerful that nothing, not even light, can escape its grasp.

But just as Olympic boxing teams have their flyweights, somewhere out there in the depths of space exists the lightest black hole in the universe. It’s still a tough guy, but it’s smaller and lighter than all other members of its kind.

Astronomers may never find the universe’s lightest black hole, but in results announced on March 31, they have come close. Nikolai Shaposhnikov and Lev Titarchuk, who work at NASA’s Goddard Space Flight Center in Greenbelt, Md., have identified the smallest known black hole in the universe. This black hole would weigh the same as 3.8 of our Suns if it could be put on a giant scale.

The Sun is a huge object, and could contain more than a million Earths. So an object weighing the same as 3.8 Suns might sound like a lot. But it’s a pipsqueak when compared to all other known black holes. Previously, the smallest known black hole would weigh about 6.3 Suns, and some black holes tip the scales at millions or even billions of times that of our Sun.

Source: NASA recent news
 

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Awesome Post BASS !!

THANK YOU for your contribution !! !!





10 new planets discovered outside our solar system

UNIVERSITY OF CALIFORNIA-SANTA BARBARA NEWS RELEASE
Posted: April 1, 2008


An international team of astronomers has found 10 new "extra solar" planets, planets that orbit stars other than our sun.

The team used a system of robotic cameras that yield a great deal of information about these other worlds, some of which are quite exotic. The system is expected to revolutionize scientific understanding of how planets form.

Two participating astronomers from the U.S. are Rachel Street and Tim Lister. Street is a postdoctoral fellow at the University of California, Santa Barbara and the Las Cumbres Observatory Global Telescope Network (LCOGTN) located in Santa Barbara. Lister is a project scientist with LCOGTN.

Team leader, Don Pollaco of Queen's University, Belfast, Northern Ireland, will announce the findings in his talk at the Royal Astronomical Society's national astronomy meeting in the U.K. on Wednesday, April 2.

The new international collaboration is called "SuperWASP," for Wide Area Search for Planets.

This technique of locating the planets gives more information about the formation and evolution of the planets than the gravitational technique. Astronomers look for "transits," moments when the planets pass in front of the star, like an eclipse, as viewed from the Earth.

In the last six months the SuperWASP team has used two batteries of cameras, one in Spain's Canary Islands and one in South Africa, to discover the 10 new extra solar planets.

With the gravitational technique, scientists have discovered around 270 extra solar planets since the early 1990s. They measured the gravitational pull on the star that is exerted by the orbiting planet. As the planet moves, it pulls on the star, tugging it back and forth. However, making these discoveries depends on looking at each star over a period of weeks or months, so the pace of discovery is slow.

The SuperWASP technique involves two sets of cameras to watch for events known as transits, where a planet passes directly in front of a star and blocks out some of the star's light. From the Earth the star temporarily appears a little fainter. The

SuperWASP cameras work as robots, surveying a large area of the sky at once. Each night astronomers receive data from millions of stars. They can then check for transits and hence planets. The transit technique also allows scientists to deduce the size and mass of each planet.

A team of collaborators around the world follows up each possible planet found by SuperWASP with more detailed observations to confirm or reject the discovery.

The astronomers working at the Las Cumbres Observatory Global Telescope Network (LCOGTN), affiliated with UC Santa Barbara, use robotically controlled telescopes in Arizona, Hawaii, and Australia. These telescopes provide high quality data used to select the best targets for intense observation. This, together with data from the Nordic Optical Telescope in La Palma, Spain; the Swiss Euler Telescope in Chile; and the Observatoire de Haute Provence in Southern France; provides the final confirmation of the new discoveries.

A total of 46 planets have been found to transit their stars. Since they started operation in 2004, the SuperWASP cameras have found 15 of these. SuperWASP is the most successful transit survey in the world.

The planets discovered by SuperWASP have masses between a middle weight of half the size of Jupiter to more than eight times the size of Jupiter, the largest planet in our solar system.

A number of these new worlds are very exotic. For example, a year, or one orbit, on WASP-12b, is just a bit over one day. This planet is so close to its star that its daytime temperature could reach a searing 2300 degrees Celsius.

Lister and Street from LCOGTN/UCSB are delighted with the results. Street described the discovery as a "very big step forward for the field."

Lister said, "The flood of new discoveries from SuperWASP will revolutionize our understanding of how planets form. LCOGTN's flexible global network of telescopes is an indispensable part of the worldwide effort to learn about the new planets."

Las Cumbres Observatory Global Telescope Network (LCOGTN) is a privately funded, nonprofit organization that is creating a cutting edge science program paired with an innovative education program.


SOURCE:SPACEFLIGHTNOW.ORG
 

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Black hole thrown out of parent galaxy
BY DR EMILY BALDWIN
ASTRONOMY NOW
Posted: April 30, 2008


By an enormous burst of gravitational waves that accompanies the merger of two black holes, a newly formed black hole has been booted out of its parent galaxy at thousands of kilometres per second, confirming theories that extreme ejection events like this can occur and aren’t only plausible in supercomputer simulations.

When two black holes merge, waves of gravitational radiation ripple outward through the galaxy at the speed of light. Because the waves are emitted mainly in one direction, the black hole is forced to recoil in the opposite direction. The result is that the black hole is catapulted out from its normal location in the nucleus of the galaxy, and if the kick velocity is high enough, the black hole can completely escape the gravitational clutches of its parent galaxy. The discovery of a black hole obeying these rules is the first direct observation of its kind, and the astrophysicists working on the project, lead by Stefanie Komossa from the Max Planck Institute for Extraterrestrial Physics (MPE), have confirmed that the several 100 million solar mass black hole was ejected at a speed of 2650 kilometres per second at a distance of 10 billion light years. The black hole’s accretion disc gas is expected to continue to feed the recoiling black hole for millions of years to come.



The new discovery is important as it indirectly proves that black holes do merge, and that these events are sometimes accompanied by large kicks. But another implication is that there must be galaxies without black holes in their nuclei, as well as black holes which float forever in space between the galaxies, which raises a set of new questions: Did galaxies and black holes form and evolve jointly in the early Universe? Or was there a population of galaxies which had been deprived of their central black holes? And if so, how was the evolution of these galaxies different from that of galaxies that retained their black holes?

By consolidating theoretical ideas with direct observations from the ground and from space, the astrophysicists are preparing to answer these questions. But whatever the outcome, this first observation will have far-reaching consequences for our understanding of galaxy formation and evolution in the early Universe.


SOURCE:SPACEFLIGHTNOW.COM

 

Offline neilep

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Iron 'snow' helps maintain Mercury's magnetic field
UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN NEWS RELEASE


CHAMPAIGN, Ill. - New scientific evidence suggests that deep inside the planet Mercury, iron "snow" forms and falls toward the center of the planet, much like snowflakes form in Earth's atmosphere and fall to the ground.

The movement of this iron snow could be responsible for Mercury's mysterious magnetic field, say researchers from the University of Illinois and Case Western Reserve University. In a paper published in the April issue of the journal Geophysical Research Letters, the scientists describe laboratory measurements and models that mimic conditions believed to exist within Mercury's core.

"Mercury's snowing core opens up new scenarios where convection may originate and generate global magnetic fields," said U. of I. geology professor Jie "Jackie" Li. "Our findings have direct implications for understanding the nature and evolution of Mercury's core, and those of other planets and moons."

Mercury is the innermost planet in our solar system and, other than Earth, the only terrestrial planet that possesses a global magnetic field. Discovered in the 1970s by NASA's Mariner 10 spacecraft, Mercury's magnetic field is about 100 times weaker than Earth's. Most models cannot account for such a weak magnetic field.

Made mostly of iron, Mercury's core is also thought to contain sulfur, which lowers the melting point of iron and plays an important role in producing the planet's magnetic field.

"Recent Earth-based radar measurements of Mercury's rotation revealed a slight rocking motion that implied the planet's core is at least partially molten," said Illinois graduate student Bin Chen, the paper's lead author. "But, in the absence of seismological data from the planet, we know very little about its core."

To better understand the physical state of Mercury's core, the researchers used a multi-anvil apparatus to study the melting behavior of an iron-sulfur mixture at high pressures and high temperatures.

In each experiment, an iron-sulfur sample was compressed to a specific pressure and heated to a specific temperature. The sample was then quenched, cut in two, and analyzed with a scanning electron microscope and an electron probe microanalyzer.

"Rapid quenching preserves the sample's texture, which reveals the separation of the solid and liquid phases, and the sulfur content in each phase," Chen said. "Based on our experimental results, we can infer what is going on in Mercury's core."

As the molten, iron-sulfur mixture in the outer core slowly cools, iron atoms condense into cubic "flakes" that fall toward the planet's center, Chen said. As the iron snow sinks and the lighter, sulfur-rich liquid rises, convection currents are created that power the dynamo and produce the planet's weak magnetic field.

Mercury's core is most likely precipitating iron snow in two distinct zones, the researchers report. This double-snow state may be unique among the terrestrial planets and terrestrial-like moons in our solar system.

"Our findings provide a new context into which forthcoming observational data from NASA's MESSENGER spacecraft can be placed," Li said. "We can now connect the physical state of our innermost planet with the formation and evolution of terrestrial planets in general."

With Li and Chen, Case Western Reserve University planetary geodynamics professor Steven A. Hauck II was a co-author of the paper.

The work was funded by the National Science Foundation.
 

Offline Lincon

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I am new to this forum for posting,In another new study reported at the conference, Emmanuel Minot of Stanford University Medical School and his colleagues tested about 2,000 employees of Wisconsin government agencies. Obesity was common in that population, and volunteers who slept either significantly less or more than the overall average tended to be heavier than people getting a moderate amount of sleep, Minot reports. Compared with people who slept 8 hours a night, those who slept 5 hours had 16 percent lower lepton concentrations and 15 percent higher grueling concentrations in their blood.
Ultimately i like to write that Science is the search of truth.

Lincon


mod edit - spammy link removed


« Last Edit: 12/03/2009 16:10:35 by BenV »
 

Offline SieWhange

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Hi neilep ...it was a nice method for research of Preserved in crystal.It is very much interesting post.

« Last Edit: 23/08/2008 11:16:22 by BenV »
 

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Hi neilep ...it was a nice method for research of Preserved in crystal.It is very much interesting post.



Thank You. Glad you enjoyed it.
 

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Mystery star cluster has three different birthdays
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: July 12, 2008

Imagine having three clocks in your house, each chiming at a different time. Astronomers have found the equivalent of three out-of-sync "clocks" in the ancient open star cluster NGC 6791. The dilemma may fundamentally challenge the way astronomers estimate cluster ages, researchers said.

Using NASA's Hubble Space Telescope to study the dimmest stars in the cluster, astronomers uncovered three different age groups. Two of the populations are burned-out stars called white dwarfs. One group of these low-wattage stellar remnants appears to be 6 billion years old, another appears to be 4 billion years old. The ages are out of sync with those of the cluster's normal stars, which are 8 billion years old.

"The age discrepancy is a problem because stars in an open cluster should be the same age. They form at the same time within a large cloud of interstellar dust and gas. So we were really puzzled about what was going on," explained astronomer Luigi Bedin, who works at the Space Telescope Science Institute in Baltimore, Md.

Ivan King of the University of Washington and leader of the Hubble study said: "This finding means that there is something about white dwarf evolution that we don't understand."

After extensive analysis, members of the research team realized how the two groups of white dwarfs can look different and yet have the same age. It is possible that the younger- looking group consists of the same type of stars, but the stars are paired off in binary-star systems, where two stars orbit each other. Because of the cluster's great distance, astronomers see the paired stars as a brighter single star.

"It is their brightness that makes them look younger," said team member Maurizio Salaris of Liverpool John Moores University in the United Kingdom.

Binary systems are also a significant fraction of the normal stellar population in NGC 6791, and are also observed in many other clusters. This would be the first time they have been found in a white-dwarf population.

"Our demonstration that binaries are the cause of the anomaly is an elegant resolution of a seemingly inexplicable enigma," said team member Giampaolo Piotto the University of Padova in Italy.

Bedin and his colleagues are relieved that they now have only two ages to reconcile: an 8-billion-year age of the normal stellar population and a 6-billion-year age for the white dwarfs. All that is needed is a process that slows down white-dwarf evolution, the researchers said.

Hubble's Advanced Camera for Surveys analyzed the cooling rate of the entire population of white dwarfs in NGC 6791, from brightest to dimmest. Most star clusters are too far away and the white dwarfs are too faint to be seen by ground-based telescopes, but Hubble's powerful vision sees many of them.

White dwarfs are the smoldering embers of Sun-like stars that no longer generate nuclear energy and have burned out. Their hot remaining cores radiate heat for billions of years as they slowly fade into darkness. Astronomers have used white dwarfs as a reliable measure of the ages of star clusters, because they are the relics of the first cluster stars that exhausted their nuclear fuel.

White dwarfs have long been considered dependable because they cool down at a predictable rate-the older the dwarf, the cooler it is, making it a seemingly perfect clock that has been ticking for almost as long as the cluster has existed.

NGC 6791 is one of the oldest and largest open clusters known, about 10 times larger than most open clusters and containing roughly 10,000 stars. The cluster is located in the constellation Lyra.

The first results appeared in the May 10 issue of The Astrophysical Journal, and the clarification about binaries was in the May 20 issue of The Astrophysical Journal Letters.

Other members of the research team are Santi Cassisi of the Collurania Astronomical Observatory in Italy, and Jay Anderson, of the Space Telescope Science Institute.




source: Spaceflightnow.org
 

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Rare 'star-making machine' found in distant universe
NASA/JPL NEWS RELEASE
Posted: July 11, 2008

Astronomers have uncovered an extreme stellar machine -- a galaxy in the very remote universe pumping out stars at a surprising rate of up to 4,000 per year. In comparison, our own Milky Way galaxy turns out an average of just 10 stars per year.

The discovery, made possible by several telescopes including NASA's Spitzer Space Telescope, goes against the most common theory of galaxy formation. According to the theory, called the Hierarchical Model, galaxies slowly bulk up their stars over time by absorbing tiny pieces of galaxies -- and not in one big burst as observed in the newfound "Baby Boom" galaxy.

"This galaxy is undergoing a major baby boom, producing most of its stars all at once," said Peter Capak of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena. "If our human population was produced in a similar boom, then almost all of the people alive today would be the same age." Capak is lead author of a new report detailing the discovery in the July 10th issue of Astrophysical Journal Letters.

The Baby Boom galaxy, which belongs to a class of galaxies called starbursts, is the new record holder for the brightest starburst galaxy in the very distant universe, with brightness being a measure of its extreme star-formation rate. It was discovered and characterized using a suite of telescopes operating at different wavelengths. NASA's Hubble Space Telescope and Japan's Subaru Telescope, atop Mauna Kea in Hawaii, first spotted the galaxy in visible-light images, where it appeared as an inconspicuous smudge due to is great distance.

It wasn't until Spitzer and the James Clerk Maxwell Telescope, also on Mauna Kea in Hawaii, observed the galaxy at infrared and submillimeter wavelengths, respectively, that the galaxy stood out as the brightest of the bunch. This is because it has a huge number of youthful stars. When stars are born, they shine with a lot of ultraviolet light and produce a lot of dust. The dust absorbs the ultraviolet light but, like a car sitting in the sun, it warms up and re-emits light at infrared and submillimeter wavelengths, making the galaxy unusually bright to Spitzer and the James Clerk Maxwell Telescope.

To learn more about this galaxy's unique youthful glow, Capak and his team followed up with a number of telescopes. They used optical measurements from Keck to determine the exact distance to the galaxy -- a whopping12.3 billion light-years. That's looking back to a time when the universe was 1.3 billion years old (the universe is approximately 13.7 billion years old today).

"If the universe was a human reaching retirement age, it would have been about 6 years old at the time we are seeing this galaxy," said Capak.

The astronomers made measurements at radio wavelengths with the National Science Foundation's Very Large Array in New Mexico. Together with Spitzer and James Clerk Maxwell data, these observations allowed the astronomers to calculate a star-forming rate of about 1,000 to 4,000 stars per year. At that rate, the galaxy needs only 50 million years, not very long on cosmic timescales, to grow into a galaxy equivalent to the most massive ones we see today.

While galaxies in our nearby universe can produce stars at similarly high rates, the farthest one known before now was about 11.7 billion light-years away, or a time when the universe was 1.9 billion years old.

"Before now, we had only seen galaxies form stars like this in the teenaged universe, but this galaxy is forming when the universe was only a child," said Capak. "The question now is whether the majority of the very most massive galaxies form very early in the universe like the Baby Boom galaxy, or whether this is an exceptional case. Answering this question will help us determine to what degree the Hierarchical Model of galaxy formation still holds true."

"The incredible star-formation activity we have observed suggests that we may be witnessing, for the first time, the formation of one of the most massive elliptical galaxies in the universe," said co-author Nick Scoville of Caltech, the principal investigator of the Cosmic Evolution Survey, also known as Cosmos. The Cosmos program is an extensive survey of a large patch of distant galaxies across the full spectrum of light.

"The immediate identification of this galaxy with its extraordinary properties would not have been possible without the full range of observations in this survey," said Scoville.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.
 

Source:spaceflightnow.org
 

Offline neilep

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Primordial fish had rudimentary fingers

Tetrapods, the first four-legged land animals, are regarded as the first organisms that had fingers and toes. Now researchers at Uppsala University can show that this is wrong. Using medical x-rays, they found rudiments of fingers in the fins in fossil Panderichthys, the “transitional animal,” which indicates that rudimentary fingers developed considerably earlier than was previously thought.

Our fish ancestors evolved into the first four-legged animals, tetrapods, 380 million years ago. They are the forerunners of all birds, mammals, crustaceans, and batrachians. Since limbs and their fingers are so important to evolution, researchers have long wondered whether they appeared for the first time in tetrapods, or whether they had evolved from elements that already existed in their fish ancestors.

When they examined genes that are necessary for the evolution of fins in zebrafish (a ray-finned fish that is a distant relative of coelacanth fishes) and compared them with the gene that regulates the development of limbs in mice, researchers found that zebrafish lacked the genetic mechanisms that are necessary for the development of fingers. It was therefore concluded that fingers appeared for the first time in tetrapods. This reading was supported by the circumstance that the fossil Panderichthys, a “transitional animal” between fish and tetrapod, appeared to lack finger rudiments in their fins.

In the present study, to be published in Nature, medical x-rays (CT scans) were used to reconstruct a three-dimensional image of Panderichthys fins. The results show hitherto undiscovered elements that constitute rudiments of fingers in the fins. Similar rudiments have been demonstrated once in the past, two years ago in Tiktaaliks, which is a more tetrapod-like group. Together with information about fin development in sharks, paddlefish, and Australian lungfish, the scientists can now definitively conclude that fingers were not something new in tetrapods.

“This was the key piece of the puzzle that confirms that rudimentary fingers were already present in ancestors of tetrapods,” says Catherine Boisvert.

Source: Eureka Alert
 

Offline Bass

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Kind of gives those restaurant "fish fingers" a whole new meaning, eh? ;D
 

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