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Warnings on Woeful Wi-Fi Security

The explosion of wireless networks at the heart of some of the world’s largest commercial cities is exposing businesses to “drive-by hacking” and other security risks, experts have warned. Research commissioned by RSA Security revealed that more than one third of businesses with wireless networks are open to abuse from hackers and criminals in the street or a neighbouring building.

“For a potential hacker it is almost a case of walking down the street and trying all the doors until one opens - it is almost inevitable that one will,” said John Worrall, vice-president of worldwide marketing at RSA Security, Inc. “Our research shows that wireless networks in Europe’s financial capitals alone are growing at an annual rate of up to 66% and more than one third of businesses remain unprotected from this type of attack.”

Researchers undertook studies in the business centers of New York City, San Francisco, London and Frankfurt. In all cities, more than one third of wireless business networks were found to be unsecured - 38% of businesses in New York, 35% in San Francisco, 36% in London and 34% in Frankfurt.

The survey also revealed that many businesses had failed to take basic security precautions such as reconfiguring their default network settings. This means that wireless network access points could still be broadcasting valuable information that could be used by potential hackers and assist them in launching an attack. In London 26% of access points still had default settings; 30% in Frankfurt; 31% in New York and 28% in San Francisco.

In addition to the business security issues, researchers also found an explosion in public access wireless hotspots: 12% of all wireless network access points in London fell into this category, compared with 24% in Frankfurt, 21% in New York and 12% in San Francisco.

With a laptop computer and free software available from the Internet, researchers were able to pick up information from company wireless networks simply by driving around the cities’ streets. In the wrong hands this type of easy access to a corporate network could be used to get hold of confidential information, disrupt business - or the network could be used to launch an Internet attack on another organization.

The research, commissioned by RSA Security, the leader in protecting identities and information access, and undertaken by independent information security specialists netSurity, was designed to quantify the extent to which companies’ wireless networks 'leak' data traffic into the street, providing potential access to hackers from their car or a nearby building.

The research executive summaries - including wireless network security advice - are available on the RSA Security website at www.rsasecurity.com, or by e-mail at pr@rsasecurity.com.

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Scientists Solve Mystery of Meteor Crater's Missing Melted Rocks

Scientists have discovered why there isn't much impact-melted rock at Meteor Crater in northern Arizona.

The iron meteorite that blasted out Meteor Crater almost 50,000 years ago was traveling much slower than has been assumed, University of Arizona Regents' Professor H. Jay Melosh and Gareth Collins of the Imperial College London report in Nature (March 10).

"Meteor Crater was the first terrestrial crater identified as a meteorite impact scar, and it's probably the most studied impact crater on Earth," Melosh said. "We were astonished to discover something entirely unexpected about how it formed."

The meteorite smashed into the Colorado Plateau 40 miles east of where Flagstaff and 20 miles west of where Winslow have since been built, excavating a pit 570 feet deep and 4,100 feet across - enough room for 20 football fields.

Previous research supposed that the meteorite hit the surface at a velocity between about 34,000 mph and 44,000 mph (15 km/sec and 20 km/sec).

Melosh and Collins used their sophisticated mathematical models in analyzing how the meteorite would have broken up and decelerated as it plummeted down through the atmosphere.

About half of the original 300,000 ton, 130-foot-diameter (40-meter-diameter) space rock would have fractured into pieces before it hit the ground, Melosh said. The other half would have remained intact and hit at about 26,800 mph (12 km/sec), he said.

That velocity is almost four times faster than NASA's experimental X-43A scramjet -- the fastest aircraft flown -- and ten times faster than a bullet fired from the highest-velocity rifle, a 0.220 Swift cartridge rifle. But it's too slow to have melted much of the white Coconino formation in northern Arizona, solving a mystery that's stumped researchers for years.

Scientists have tried to explain why there's not more melted rock at the crater by theorizing that water in the target rocks vaporized on impact, dispersing the melted rock into tiny droplets in the process. Or they've theorized that carbonates in the target rock exploded, vaporizing into carbon dioxide.

"If the consequences of atmospheric entry are properly taken into account, there is no melt discrepancy at all," the authors wrote in Nature. "Earth's atmosphere is an effective but selective screen that prevents smaller meteoroids from hitting Earth's surface," Melosh said.

When a meteorite hits the atmosphere, the pressure is like hitting a wall. Even strong iron meteorites, not just weaker stony meteorites, are affected.

"Even though iron is very strong, the meteorite had probably been cracked from collisions in space," Melosh said. "The weakened pieces began to come apart and shower down from about eight-and-a-half miles (14 km) high. And as they came apart, atmospheric drag slowed them down, increasing the forces that crushed them so that they crumbled and slowed more."

Melosh noted that mining engineer Daniel M. Barringer (1860-1929), for whom Meteor Crater is named, mapped chunks of the iron space rock weighing between a pound and a thousand pounds in a 6-mile-diameter circle around the crater. Those treasures have long since been hauled off and stashed in museums or private collections. But Melosh has a copy of the obscure paper and map that Barringer presented to the National Academy of Sciences in 1909.

At about 3 miles (5 km) altitude, most of the mass of the meteorite was spread in a pancake shaped debris cloud roughly 650 feet (200 meters) across.

The fragments released a total 6.5 megatons of energy between 9 miles (15 km) altitude and the surface, Melosh said, most of it in an airblast near the surface, much like the tree-flattening airblast created by a meteorite at Tunguska, Siberia, in 1908.

The intact half of the Meteor Crater meteorite exploded with at least 2.5 megatons of energy on impact, or the equivalent of 2.5 tons of TNT.

Elisabetta Pierazzo and Natasha Artemieva of the Planetary Science Institute in Tucson, Ariz., have independently modeled the Meteor Crater impact using Artemieva's Separated Fragment model. They find impact velocities similar to that which Melosh and Collins propose.

Melosh and Collins began analyzing the Meteor Crater impact after running the numbers in their Web-based "impact effects" calculator, an online program they developed for the general public. The program tells users how an asteroid or comet collision will affect a particular location on Earth by calculating several environmental consequences of the impact.

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Hubble Weighs in on the Heaviest Stars in the Galaxy

Unlike humans, stars are born with all the weight they will ever have. A human's birth weight varies by just a few pounds, but a star's weight ranges from less than a tenth to more than 100 times the mass of our Sun. Although astronomers know that stars come in a variety of masses, they are still stumped when it comes to figuring out if stars have a weight limit at birth.

Now astronomers have taken an important step toward establishing a weight limit for stars. Using NASA's Hubble Space Telescope, astronomers made the first direct measurement within our Milky Way Galaxy that stars have a limit to how large they can form. Studying the densest known cluster of stars in our galaxy, the Arches cluster, astronomers determined that stars are not created any larger than about 150 times the mass of our Sun, or 150 solar masses.

The finding takes astronomers closer to understanding the complex star-formation process and gives the strongest footing yet to the idea that stars have a weight limit. Knowing how large a star can form may offer important clues to how the universe makes stars. Massive stars are the "movers and shakers" of the universe. They manufacture many of the heavier elements in the cosmos, which are the building blocks for new stars and planets. Hefty stars also may be the source of titanic gamma-ray bursts, which flood a galaxy with radiation.

"This is an incredible cluster that contains a rich collection of some of the most massive stars in the galaxy, yet it appears to be ‘missing' stars more massive than 150 times the mass of our Sun," said astronomer Donald F. Figer of the Space Telescope Science Institute in Baltimore, Md. "Theories predict that the more massive the cluster, the more massive the stars within it. We looked at one of the most massive clusters in our galaxy and found that there is a sharp cutoff to how large a star can form.

"Standard theories predict 20 to 30 stars in the Arches cluster with masses between 130 and 1,000 solar masses. But we found none. If they had formed, we would have seen them. If the prediction was only one or two stars and we saw none, then we could claim that our result could be due to statistical errors."

Figer is pursuing follow-up studies to determine an upper limit in other star clusters to test his result. His finding is consistent with statistical studies of smaller-mass star clusters in our galaxy and with observations of a massive star cluster known as R136 in our galactic neighbor, the Large Magellanic Cloud. In that cluster, astronomers discovered that stars were not created any larger than 150 solar masses.

Astronomers have been uncertain about how large a star can get before it cannot hold itself together and blows itself apart. Even with the advances in technology, astronomers do not know enough about the details of the star-formation process to determine an upper-mass limit for stars. Consequently, theories have predicted that stars can be anywhere between 100 to 1,000 times more massive than our Sun. Predicting a lower weight limit for stars has been easier. Objects less than one-tenth a solar mass are not hefty enough to sustain nuclear fusion in their cores and shine as stars.

Making this finding was so tricky that Figer spent seven years puzzling over the Hubble data. The results are published in the March 10th issue of the journal Nature.

"Knowing that extraordinary claims demand extraordinary proof, I scratched my head for a long time trying to figure out why the result might be wrong," he said.

Figer used Hubble's Near Infrared Camera and Multi-Object Spectrometer to study hundreds of stars ranging from 6 to 130 solar masses. (Although Figer did not find any stars larger than 130 solar masses, he conservatively set the upper limit at 150 solar masses.) The Arches cluster is a youngster, about 2 to 2.5 million years old, and resides 25,000 light-years away in our galaxy's hub, a hotbed of massive star formation. In this rough-and-tumble region, huge clouds of gas collide to form behemoth stars.

Hubble's infrared camera is well suited to analyze the Arches because it penetrates the dusty core of our galaxy and produces sharp images, allowing the telescope to see individual stars in a tightly packed cluster. Figer estimated the stars' masses by measuring the ages of the cluster and the brightness of the individual stars. He also collaborated with Francisco Najarro of the Instituto de Estructura de la Materia in Madrid, who produced detailed models to confirm the masses, chemical abundances, and ages of the cluster's stars.

A cluster must meet a long list of requirements for astronomers to use it for identifying an upper-mass limit. The cluster must be hefty enough, about 10,000 solar masses, to produce stars large enough to probe the upper limit. A cluster also cannot be too young or too old. Selecting an older cluster - beyond 2.5 million years - means that many of the massive young stars have already exploded as supernovas. In a very young cluster - less than 2 million years old - many of the stars are still enshrouded in their natal dust clouds, and astronomers cannot see them.

Another important factor is a cluster's distance from Earth. Astronomers must know the cluster's distance to reliably estimate the brightness of its stars, a key ingredient used to estimate a star's mass. The cluster also must be close enough to see individual stars. The Arches cluster is the only cluster in the galaxy that meets all of those requirements, Figer said.

The Arches outshines almost every other star cluster in the galaxy. With a mass equivalent to more than 10,000 stars like our Sun, the monster cluster is 10 times heavier than typical young star clusters, such as the Orion cluster, scattered throughout our Milky Way. If our galactic neighborhood were as cluttered with stars, more than 100,000 stars would fill the void of space between our Sun and its nearest neighbor, the star Alpha Centauri, 4.3 light-years away. Astronomers estimate that only 1 out of every 10 million stars in the galaxy is as bright as the stars in the Arches cluster. At least a dozen of the cluster's stars weigh about 100 times the mass of our Sun.

Figer cautions that the upper limit does not rule out the existence of stars larger than 150 solar masses. Such hefty stars, if they exist, could have gained weight by merging with another massive star. For example, the young Pistol star, located near our galactic hub, is 150 to 250 times more massive than our Sun. This behemoth star, however, seems out of place because it dwells in a neighborhood of older stars. One way to explain this apparent paradox, Figer said, is that the Pistol could be a "born-again" star, formed from the merger of two stars. His explanation is not just theory. Astronomers have found older stars that have been reborn through mergers with other stars in ancient globular star clusters.

The Pistol also could be part of a double-star system that is masquerading as a single giant star. The two stars have not been unmasked because they cannot be resolved by even the Hubble telescope.

Double-star systems, astronomers also caution, could make up some of the most massive stars in the Arches cluster. This means that the upper limit in the Arches could be lower than 150 solar masses, but not any higher.

Figer's next step is to pinpoint more clusters to test his weight limit. Several telescopes, including the Spitzer Space Telescope, have been searching for new star clusters in our Milky Way. In the last two years, the number of known clusters in our galaxy has doubled from a few hundred to 500, Figer said. Many of the newly found clusters are compiled in the Two Micron All Sky Survey (2MASS) catalogue. Figer already has identified about 130 of these newly discovered clusters as possible candidates to study. NASA has recognized Figer's important work by giving him a five-year Long Term Space Astrophysics award, which will support his hunt for the most massive stars in the Milky Way.

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Malaria Drastically Underestimated

A new comprehensive investigation into the extent of the deadliest form of malaria shows there were over half a billion cases in 2002, according to researchers from the Kenya Unit of the Centre for Tropical Medicine and the Department of Zoology.

More than two-thirds of these cases occurred in Africa, where Plasmodium falciparum malaria mostly affects children under-five. But far more cases than previously thought take place in SE Asia. The latest estimate of 515m episodes, is described in the March 10 edition of Nature and emphasizes that malaria treatment requires more investment for more people in more areas of the world than governments and health agencies might have anticipated.

This research is timely because the United Nations has set-up initiatives targeting malaria. The Millennium Development Goal aims to halt the spread of the disease by 2015 and Roll Back Malaria is designed to halve mortality in the next six years.

Scientists from the University of Oxford, based at the Kenya Medical Research Institute - Wellcome Trust Research Programme used contemporary and historical epidemiological, geographical and demographic information to model where people live, the likelihood of infection from malaria parasites and susceptibility to developing the disease. New methods in Geographic Information Systems and data from earth orbiting satellites were used.

Professor Bob Snow led the research, which suggests 2.2 billion people are at risk from malaria.

‘We have taken a science-driven approach to working out who is at risk, where they are located and what their chances would be of developing an attack of malaria. Our work has demonstrated that nearly 25 per cent of worldwide cases occur in South East Asia and the Western Pacific - whereas most people regard Plasmodium falciparum disease a problem particular to Africa,” Snow said.