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Largest digital survey of Milky Way released by astronomers

Tue, 11 Dec 2007 09:52:00 -0500

Astronomers have released the largest optical digital survey of the Milky Way galaxy, which has stunning red images of nebulae and stars.

Conducted by a collaborative team of over 50 astronomers from the IPHAS (INT Photometric H-Alpha Survey) consortium, the survey used the Isaac Newton Telescope on La Palma to look at the light emitted by hydrogen ions.

By including some 200 million unique objects in the newly released catalogue, the IPHAS survey will help to foster studies that can be at once both comprehensive and subtle, of the stellar demographics of the Milky Way and of its three-dimensional structure.

"Using the distinctive Hydrogen marker we are able to look at some of the least understood stars in the Galaxy - those at the early and very late stages of their life cycles. These represent less than one in a thousand stars, so the IPHAS data will greatly improve our picture of stellar evolution," said Professor Janet Drew of the University of Hertfordshire.

According to the Science and Technology Facilities Council in the UK, this initial data release is of observations of the Northern Plane of the Milky Way (the star filled section) that covers 1600 sq degrees, in two broadband colours, and a narrow band filter sensitive to the emission of Hydrogen in the red part of the spectrum (H-alpha emission).

The image resolution is high enough to permit the detection of individual stars exhibiting H-alpha emission, in addition to the diffuse gas that makes up the often-beautiful glowing nebulae that lower spatial resolution surveys have made known to us before.

The IPHAS database is already revealing much information.

For example, IPHAS team members from the University of Southampton, have led an effort to extract and catalogue the brighter H-alpha emission line stars revealed so far by the survey.

Also, this list of nearly 5000 objects is already the longest single list of its kind.

Another important finding of this survey is that the distribution of these special objects, across the northern sky, traces 'hot spots' of recently formed stars in our Galaxy much more convincingly than has been possible hitherto.

The IPHAS survey will eventually be extended to cover the entire galactic plane of our galaxy, with a coverage approaching 4000 square degrees. (ANI)

New NASA mission to reveal moon's internal structure, evolution

Tue, 11 Dec 2007 09:46:00 -0500

NASA's Associate Administrator for Science, Alan Stern, has announced a new mission that will peer deep inside the moon to reveal its anatomy and history.

The Gravity Recovery and Interior Laboratory (GRAIL) mission is a part of NASA's Discovery Program and will cost 375 million dollars. It is scheduled to be launched in 2011.

GRAIL will fly twin spacecraft in tandem orbits around the moon for several months to measure its gravity field in unprecedented detail. The mission also will answer

longstanding questions about Earth's moon and provide scientists a better understanding of how Earth and other rocky planets in the solar system formed.

"GRAIL's revolutionary capabilities stood out in this Discovery mission competition owing to its unsurpassed combination of high scientific value and low technical and

programmatic risk. GRAIL also offers to bring innovative Earth studies techniques to the moon as a precursor to their possible later use at Mars and other planets," Stern

said.

Scientists will use the gravity field information from the two satellites to X-ray the moon from crust to core to reveal the moon's subsurface structures and, indirectly, its

thermal history.

The study technique GRAIL will use was pioneered by the joint U.S.-German Earth observing Gravity Recovery and Climate Experiment, or GRACE, mission launched in

2002.

The GRACE satellites measure gravity changes related to the movement of mass within the Earth, such as the melting of ice at the poles and changes in ocean circulation.

As with GRACE, both GRAIL spacecraft will be launched on a single launch vehicle.

GRAIL's principal investigator is Maria Zuber of the Massachusetts Institute of Technology. Zuber's team of expert scientists and engineers includes former NASA astronaut

Sally Ride, who will lead the mission's public outreach efforts. A camera aboard each spacecraft will allow students and the public to interact with observations from the

satellites.

Each GRAIL spacecraft will carry the cameras to documents their views from lunar orbits.

GRAIL will support NASA's exploration goals as the agency returns humans to the moon by 2020. In 2008, the agency will launch the Lunar Reconnaissance Orbiter, or

LRO, to circle the moon for at least a year and take measurements to identify future robotic and human landing sites.
The orbiter also will look for potential lunar resources and document aspects of the lunar radiation environment.

After a 30-year hiatus, LRO represents NASA's first step toward returning humans to the moon. The orbiter will be accompanied by another spacecraft, called the Lunar

Crater Observation and Sensing Satellite mission, which will impact the lunar south pole to search for evidence of polar water frost.

This was revealed at a Monday meeting of the American Geophysical Union. (ANI)

Quantum-dot light emiting diodes can outshine their rivals: Study

Tue, 11 Dec 2007 09:46:00 -0500

The size of the quantum dots can be tuned to produce several different colours, and a study has opined that quantum-dot light-emitting diodes (LEDs) require just three to four volts of electricity to run non-stop for over 300 hours.

The study further suggests that the brightest quantum-dot LEDs can provide lighting for displays that are clearer and richer in colour, as well as being cheaper to make, than existing ones.

The devices could be used to make better displays for mobile phones and Personal Digital Assistant (PDAs), and to light larger flat-panel TV screens, claim Chinese and American researchers.

Quantum dots are nanoscale semiconductors that confine electrons in three dimensions. In this case, the quantum dots have a cadmium selenide core and a zinc sulphide "shell".

Electrons are excited to higher energy levels in the core and the shell, then fall into the empty spaces, or "holes", left behind. The dot then forms an "exciton" and emits a particle of light.

Changing the size of a QDLED makes it emit a different wavelength of light – producing red, orange, yellow, or green light.

Although standard LEDs are far more efficient, QDLEDs could be better in other ways.

The range of colours and intensity of light produced by QDLEDs promise to be better than alternative technologies.

"The brightness of the best LCD monitor on the market today is 500 candelas per square metre and the brightness of room light is about 2000 cd/m2," says Andrew Wang of Ocean NanoTech in Fayetteville, Arkansas, which developed the quantum dots.

"Our QDLEDs have reached 9000 cd/m2 in brightness, which makes them the brightest in the world."

QDLEDs are also relatively easy to make, using solution-processing techniques, such as spin coating, ink-jet printing and roll-to-roll printing, which is useful for flexible-screen applications.

The Ocean NanoTech researchers, together with Yongfang Li and Qingjiang Sun at the Chinese Academy of Sciences, are now working hard to optimise the structures of the quantum dots to further increase the lifetime and power efficiency of the devices.

For the technology to be incorporated into a product, however, it may be necessary to demonstrate the same physical phenomena using a material other than cadmium, which is a highly toxic heavy metal. (ANI)

Asteroid impact responsible for melting, recasting of EarthÃ¢â‚¬â„¢s crust

Tue, 11 Dec 2007 09:46:00 -0500

A University of Minnesota geologist has suggested that the continuous overturning, melting and re-casting of Earth's crust may have started with a massive asteroid impact in Earth's infancy.

If true, this conclusion could throw light on how and why plate tectonics did or did not get started on other worlds in our solar system and beyond, claims geologist Vicki Hansen.

"Everyone argues about when (plate tectonics) starts, but never asks about outside processes," Discovery News quotes Hansen, as saying.

"As geologists, we don't even consider impacts beyond perhaps causing one or two mass extinction events much later in Earth's history. We should at least ask the question," she said.

In an article that appears in the December issue of the journal Geology, Hansen opines that tectonic plates were set in motionover three billion years ago, when the densest materials sank to the core, and the lightest materials settled into an outermost crust, also known as the "Felsic" crust.

Meanwhile, out in space, the solar system was still pretty full of bits and pieces of failed planets -- asteroids galore.

Hansen says that if one of those of sufficient size slammed down on one of the warmer, weaker parts of young Earth's felsic crust, it could punch a hole and trigger melting in the mantle, and an eruption.

This erupted lava from the mantle would have solidified and become Earth's first heavier, more brittle "mafic" crust, and this is the sort of crust being created today at ocean spreading centres as well as pouring out of the Hawaiian Islands volcanoes, she says.

"Once started, it's an on-going process," said tectonics researcher Peter Cawood of the University of Western Australia.

"It certainly gives our ideas about sub-duction initiation a shock," Cawood told Discovery News. (ANI)

Increasing carbon dioxide threatening major sea food source

Tue, 11 Dec 2007 09:46:00 -0500

A leading scientist has warned that increasing carbon dioxide in the atmosphere may affect microbial life and deplete a major food source from sea.

Dr Ian Joint from Plymouth Marine Laboratory suggested if microscopic plants eaten by fish are affected by carbon dioxide, this might reduce a major food source from the sea, as fish provides almost a fifth of the animal protein eaten by man

Dr Joint has been studying and sequencing DNA of different ocean bacteria to find out how they would react to an increase in carbon dioxide.

“So far from one experiment we have sequenced 300 million bases of DNA, about one tenth the size of the human genome. We are analyzing this ‘ocean genome’ to see if changes might affect the productivity of the sea,” he said.

He added that bacteria still controls the world, ensuring the fertility of the planet and the non-accumulation of toxic materials

“There are many millions of different bacteria in the ocean. They control the cycling of oxygen, carbon, nitrogen and sulphur; microbes in the sea generate half of the oxygen produced globally every year,” he said.

“Bacteria made the earth suitable for animals by producing oxygen nearly 2 billion years ago. We want to find out if human activities will have a major impact on microbial life in the seas and if this is likely to be a problem for mankind in the future,” he added.

Dr Joint also said that carbon dioxide produced by humans is turning the oceans into weak acids.

And this century, the seas will be more acidic than they have been for 20 million years, he warned. (ANI)

Threatened birds much closer to extinction than earlier thought

Tue, 11 Dec 2007 09:46:00 -0500

An Assistant Professor of Biological Sciences at the University of California, San Diego, and his fellow researchers have opined that birds that are a threatened species, may be closer to extinction than earlier thought.

According to Walter Jetz, the lead author of the study, which will appear in the February 2008 issue of the journal Conservation Biology, geographic range maps that allow conservationists to estimate the distribution of birds may vastly overestimate the actual population size of threatened species and those with specific habitats.

Taking the example of the Pinyon Jay, an important seed disperser of North American pinyon pines, Jetz claims that 52 percent of its range is overestimated.

"Our study found that species ranges in general tend to get overestimated, but that this trend is particularly pronounced for birds that are threatened, rely on specialized diets or have small habitats," said Jetz.

"Our findings indicate that the ranges of most vulnerable bird species are experiencing the highest overestimation, thereby painting a rosier picture of their distributions than is actually the case," added Cagan Sekercioglu, a senior research scientist at Stanford University and a co-author of the study.

Jetz, Sekercioglu and James E.M. Watson of Britain's Oxford University evaluated geographic range overestimation and its potential ecological causes for 1,158 bird species across 4,040 well-studied survey locations in Australia, North America and Southern Africa.

Comparing the range maps with actual bird surveys, such as those conducted by the Audubon Society, the scientists found that most species actually occur in only 40 to 70 percent of the range suggested by their range maps. In other words, these birds are not actually found in 30 to 60 percent of their supposed range.

The scientists also found range overestimation increases for species with smaller ranges and with more specialized dietary and habitat requirements.

Therefore, they concluded that range maps most strongly overestimate the distribution of narrow-ranging species and ecological specialists.

As a consequence, species threatened or near threatened with extinction are also subject to particularly high range overestimation, on average 62 percent overestimation compared to 37 percent overestimation in non-threatened species, they said.

The researchers' study was limited to mostly temperate areas with relatively high-quality data on bird distributions.

Jetz believes that range maps are becoming especially important for ecologists making projections of the impact of climate change on the health of specific populations.

He said this latest study and another one that was published on August 14 this year clearly demonstrate that conservationists need to be especially careful when making predictions about future risks to species during rapid climate change. (ANI)

Excavators discover massive dinosaur Ã¢â‚¬ËœgraveyardÃ¢â‚¬â„¢ in Spain

Tue, 11 Dec 2007 09:22:00 -0500

Researchers have discovered a spectacular dinosaur "graveyard" in eastern Spain, which contains thousands of fossils.

Experts excavating the site have revealed that eight different dinosaur species have been identified among the 8,000 fossils found to date.

The dinosaur species identified include several kinds of armour-clad plant-eaters that were among the world's largest types of dinosaur.

The fossils, about 70 million-year old, were uncovered last June during the construction of a high-speed rail link near the city of Cuenca.

Scientists believe that these fossils may represent the largest and most diverse dinosaur site known in Europe.

Jose Luis Sanz, a palaeontologist of Autonomous University in Madrid, says that the fossils show a stunning array of dinosaur diversity for a period that is very poorly known in Western Europe.

"We are sure that in future, (once we have) studied the huge amount of fossil material recovered from the site, the diversity will increase," the National Geographic quoted Sanz, who is in charge of the dig, as saying in an email.

“The fossils date to some four million years before the dinosaurs went extinct, shedding new light "on these last European dinosaur ecosystems," he added.

According to him, excavations at the site called Lo Hueco indicate that the dominant plant-eaters of the period were massive, long-necked sauropods called titanosaurs, a group generally thought to include the largest animals ever to have walked the Earth.

"Titanosaurs are by far the most abundant dinosaur remains at Lo Hueco," Sanz said.

The excavations have also led to the discovery of fossils from a couple of two-legged, meat-eating dinosaurs, one of which was a six-foot-long (1.8-meter-long) dromaeosaur, a fearsomely clawed carnivore.

The identified kinds of dinosaurs also include a small, stocky Rhabdodon with large blunt teeth for grinding up vegetation, and an ankylosaur, a heavily built, squat plant-eater with a big bony club on the end of its tail for whacking predators.

According to the dig team, the fossils were found grouped together in clay and silt sediments, an indication that a river might have created the dinosaur graveyard.

"Flooding maybe was responsible for the accumulation of carcasses," Sanz said.

He further said that the site might provide further clues to understanding the demise of the dinosaurs some 66 million years ago. (ANI)

People happier with their smiles than dentistsÃ¢â‚¬â„¢ opinions

Tue, 11 Dec 2007 09:22:00 -0500

When it comes to smiling, people rate their own grins higher than their dentists do, says a study.

The study found that people younger than age 50 years were most satisfied with their smiles.

In the study, 78 patients were asked to rate their own smiles on a 100-point satisfaction scale.

The participants, who were not actively seeking cosmetic dental treatments, averaged 51 years of age and numbered 50 women and 28 men.

Later, the patients’ regular dentist and an independent periodontist rated the patients’ smiles from photographs, using the same satisfaction scale.

The analysis found that patients were more satisfied with their own smiles than dentists, rating them an average 59.1 on the 100-point scale. Dentists’ ratings of the patients’ smiles were much lower, averaging 38.6 (independent periodontist) and 40.7 (patients’ own dentist).

The researchers said that it might be difficult to understand what a smile satisfaction level of 59 really means, adding it might be more accurate to say patients are “accepting of, or contented with, their smiles.”

“The fact that the patients had much higher opinions of their smiles than we dentists did is interesting,” the researchers said.

They explained that patients expressed their opinions from memory, while the dentists made their assessments from photographs.

The researchers speculated that if the patients had used the clinicians’ detailed approach to include assessing lip lines, tooth shade, spacing, and crowding, their opinions about their smiles might have been different.

“Dentists should be aware that patients who seek esthetic services may have different perceptions of their smiles than patients who do not express such desires,” the researchers said.

The study is published in The Journal of the American Dental Association. (ANI)