Tuesday, August 4, 2009

'INVISIBILITY CLOAK' COULD PROTECT AGAINST EARTHQUAKES

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Research at the University of Liverpool has shown it is possible to develop an 'invisibility cloak' to protect buildings from earthquakes.

The seismic waves produced by earthquakes include body waves which travel through the earth and surface waves which travel across it. The new technology controls the path of surface waves which are the most damaging and responsible for much of the destruction which follows earthquakes.

The technology involves the use of concentric rings of plastic which could be fitted to the Earth’s surface to divert surface waves. By controlling the stiffness and elasticity of the rings, waves travelling through the ‘cloak’ pass smoothly into the material and are compressed into small fluctuations in pressure and density. The path of the surface waves can be made into an arc that directs the waves outside the protective cloak. The technique could be applied to buildings by installing the rings into foundations.

Sebastien Guenneau, from the University’s Department of Mathematics, who developed the technology with Stefan Enoch and Mohamed Farhat from the Fresnel Institute (CNRS) in Marseilles, France, explained: "We are able to 'tune' the cloak to the differing frequencies of incoming waves which means we can divert waves of a variety of frequencies. For each small frequency range, there is a pair of rings which does most of the work and these move about a lot – bending up and down – when they are hit by a wave at their frequency.

"The waves are then directed outside the cloak where they return to their previous size. The cloak does not reflect waves – they continue to travel behind it with the same intensity. At this stage, therefore, we can only transfer the risk from one area to another, rather than eliminate it completely."

He added: "This work has enormous potential in offering protection for densely populated areas of the world at risk from earthquakes. The challenge now is to turn our theories into real applications that can save lives – small scale experiments are underway."

Seismic waves also include coupled pressure and shear body waves which are less destructive than surface waves. Sebastien Guenneau and Sasha Movchan at the University of Liverpool, together with Michele Brun at Cagliari University, have designed an 'elastic' cloak to protect against these particular seismic waves and the team is currently seeking a suitable material to accommodate the elastic parameters of the cloak.

(Photo: U. Liverpool)

University of Liverpool

PURER WATER MADE POSSIBLE BY SANDIA ADVANCE

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By substituting a single atom in a molecule widely used to purify water, researchers at Sandia National Laboratories have created a far more effective decontaminant with a shelf life superior to products currently on the market.

Sandia has applied for a patent on the material, which removes bacterial, viral and other organic and inorganic contaminants from river water destined for human consumption, and from wastewater treatment plants prior to returning water to the environment.

“Human consumption of ‘challenged’ water is increasing worldwide as preferred supplies become more scarce,” said Sandia principal investigator May Nyman. “Technological advances like this may help solve problems faced by water treatment facilities in both developed and developing countries.”

The study was published in June 2009 in the journal Environmental Science & Technology (a publication of the American Chemical Society) and highlighted in the June 22 edition of Chemical & Engineering News. Sandia is working with a major producer of water treatment chemicals to explore the commercial potential of the compound.

The water-treatment reagent, known as a coagulant, is made by substituting an atom of gallium in the center of an aluminum oxide cluster — itself a commonly used coagulant in water purification, says Nyman.

The substitution isn’t performed atom by atom using nanoscopic tweezers but rather uses a simple chemical process of dissolving aluminum salts in water, gallium salts into a sodium hydroxide solution and then slowly adding the sodium hydroxide solution to the aluminum solution while heating.

“The substitution of a single gallium atom in that compound makes a big difference,” said Nyman. “It greatly improves the stability and effectiveness of the reagent. We’ve done side-by-side tests with a variety of commercially available products. For almost every case, ours performs best under a wide range of conditions.”

Wide-ranging conditions are inevitable, she said, when dealing with a natural water source such as a river. “You get seasonal and even daily fluctuations in pH, temperature, turbidity and water chemistry. And a river in central New Mexico has very different conditions than say, a river in Ohio.”

The Sandia coagulant attracts and binds contaminants so well because it maintains its electrostatic charge more reliably than conventional coagulants made without gallium, itself a harmless addition.

The new material also resists converting to larger, less-reactive aggregates before it is used. This means it maintains a longer shelf life, avoiding the problem faced by related commercially available products that aggregate over time.

“The chemical substitution [of a gallium atom for an aluminum atom] has been studied by Sandia’s collaborators at the University of California at Davis, but nobody has ever put this knowledge to use in an application such as removing water contaminants like microorganisms,” said Nyman.

The project was conceived and all water treatment studies were performed at Sandia, said Nyman, who worked with Sandia microbiologist Tom Stewart. Transmission electron microscope images of bacteriophages binding to the altered material were achieved at the University of New Mexico. Mass spectroscopy of the alumina clusters in solution was performed at UC Davis.

(Photo: Sandia Labs.)

Sandia National Laboratories

MAUNA KEA SELECTED FOR THIRTY METER TELESCOPE

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After careful evaluation and comparison between two outstanding candidate sites –– Mauna Kea in Hawaii and Cerro Armazones in Chile –– the board of directors of the TMT Observatory Corporation has selected Mauna Kea as the preferred site for the Thirty Meter Telescope. The TMT will be the most capable and advanced telescope ever constructed.

The announcement was made in Pasadena by UC Santa Barbara Chancellor Henry T. Yang, chairman of the board of TMT, which is a collaboration of the California Institute of Technology, the University of California, and ACURA, an organization of Canadian universities. The National Astronomical Observatory of Japan joined TMT as a collaborating institution in 2008.

When completed in 2018, the TMT will enable astronomers to detect and study light from the earliest stars and galaxies, analyze the formation of planets around nearby stars, and test many of the fundamental laws of physics.

Yang expressed excitement at this decision. "Our scientists and engineers have been designing and building the key components that will go into the telescope," Yang said. "By deciding to build on Mauna Kea, the TMT board has given a clear signal that we are ready to move forward and begin building in earnest as soon as all the necessary approvals are in place."

The TMT will integrate the latest innovations in precision control, segmented mirror design, and adaptive optics to correct for the blurring effect of Earth's atmosphere, enabling the TMT to study the Universe as clearly as if the telescope were in space. Building on the success of the twin Keck telescopes, the core technology of TMT will be a 30-meter primary mirror composed of 492 segments. This will give TMT nine times the collecting area of today's largest optical telescopes.

To ensure that the site chosen for TMT would enable the telescope to achieve its full potential, a global satellite survey was conducted, from which five outstanding candidate sites were chosen for further ground-based studies of atmospheric stability, wind patterns, temperature variation, and other meteorological characteristics that would affect the performance of the telescope.

Based on these results and extensive studies, Mauna Kea and Cerro Armazones were selected in May 2008 for further evaluation and environmental, financial, and cultural impact studies. The TMT board used the results from these meticulous research campaigns to help guide the final site-selection process.

"It was clear from all the information we received that both sites were among the best in the world for astronomical research," said Edward Stone, Caltech's Morrisroe Professor of Physics and vice chairman of the TMT board. "Each has superb observing conditions and would enable TMT to achieve its full potential of unlocking the mysteries of the Universe.

"In the final analysis, the board selected Mauna Kea as the site for TMT. The atmospheric conditions, low average temperatures, and very low humidity will open an exciting new discovery space using adaptive optics and infrared observations. Working in concert with the partners' existing facilities on Mauna Kea will further expand the opportunities for discoveries," said Stone.

Before construction can begin on Mauna Kea, the TMT board must submit and have approved an application for a Conservation District Use Permit (CDUP) to the Hawaiian Department of Land and Natural Resources. This will be done through the community-based Office of Mauna Kea Management, which oversees the Mauna Kea summit as part of the University of Hawaii at Hilo.

The TMT project has completed its $77 million design development phase with primary financial support of $50 million from the Gordon and Betty Moore Foundation and $22 million from Canada. The project has now entered the early construction phase thanks to an additional $200 million pledge from the Gordon and Betty Moore Foundation. Caltech and the University of California each have agreed to raise matching funds of $50 million to bring the construction total to $300 million, and the Canadian partners propose to supply the enclosure, the telescope structure, and the first light adaptive optics.

University of California, Santa Barbara

THIS ARTICLE WILL SELF-DESTRUCT: A TOOL TO MAKE ONLINE PERSONAL DATA VANISH

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The University of Washington has developed a way to make such information expire. After a set time period, electronic communications such as e-mail, Facebook posts and chat messages would automatically self-destruct, becoming irretrievable from all Web sites, inboxes, outboxes, backup sites and home computers. Not even the sender could retrieve them.

"If you care about privacy, the Internet today is a very scary place," said UW computer scientist Tadayoshi Kohno. "If people understood the implications of where and how their e-mail is stored, they might be more careful or not use it as often."

The team of UW computer scientists developed a prototype system called Vanish that can place a time limit on text uploaded to any Web service through a Web browser. After a set time text written using Vanish will, in essence, self-destruct. A paper about the project went public today and will be presented at the Usenix Security Symposium Aug. 10-14 in Montreal.

The paper and research prototype are at http://vanish.cs.washington.edu/.

Co-authors on the paper are doctoral student Roxana Geambasu, assistant professor Tadayoshi Kohno, professor Hank Levy and undergraduate student Amit Levy, all with the UW's department of computer science and engineering. The research was funded by the National Science Foundation, the Alfred P. Sloan Foundation and Intel Corp.

"When you send out a sensitive e-mail to a few friends you have no idea where that e-mail is going to end up," Geambasu said. "For instance, your friend could lose her laptop or cell phone, her data could be exposed by malware or a hacker, or a subpoena could require your e-mail service to reveal your messages. If you want to ensure that your message never gets out, how do you do that?"

Many people believe that pressing the "delete" button will make their data go away.

"The reality is that many Web services archive data indefinitely, well after you've pressed delete," Geambasu said.

Simply encrypting the data can be risky in the long term, the researchers say. The data can be exposed years later, for example, by legal actions that force an individual or company to reveal the encryption key. Current trends in the computing and legal landscapes are making the problem more widespread.

"In today's world, private information is scattered all over the Internet, and we can't control the lifetime of that data," said Hank Levy. "And as we transition to a future based on cloud computing, where enormous, anonymous datacenters run the vast majority of our applications and store nearly all of our data, we will lose even more control."

The Vanish prototype washes away data using the natural turnover, called "churn," on large file-sharing systems known as peer-to-peer networks. For each message that it sends, Vanish creates a secret key, which it never reveals to the user, and then encrypts the message with that key. It then divides the key into dozens of pieces and sprinkles those pieces on random computers that belong to worldwide file-sharing networks, the same ones often used to share music or movie files. The file-sharing system constantly changes as computers join or leave the network, meaning that over time parts of the key become permanently inaccessible. Once enough key parts are lost, the original message can no longer be deciphered.

In the current Vanish prototype, the network's computers purge their memories every eight hours. (An option on Vanish lets users keep their data for any multiple of eight hours.)

Unlike existing commercial encryption services, a message sent using Vanish is kept private by an inherent property of the decentralized file-sharing networks it uses.

"A major advantage of Vanish is that users don't need to trust us, or any service that we provide, to protect or delete the data," Geambasu says.

Researchers liken using Vanish to writing a message in the sand at low tide, where it can be read for only a few hours before the tide comes in and permanently washes it away. Erasing the data doesn't require any special action by the sender, the recipient or any third party service.

"Our goal was really to come up with a system where, through a property of nature, the message, or the data, disappears," Hank Levy says.

Vanish was released today as a free, open-source tool that works with the Firefox browser. To work, both the sender and the recipient must have installed the tool. The sender then highlights any sensitive text entered into the browser and presses the "Vanish" button. The tool encrypts the information with a key unknown even to the sender.

That text can be read, for a limited time only, when the recipient highlights the text and presses the "Vanish" button to unscramble it. After eight hours the message will be impossible to unscramble and will remain gibberish forever.

Vanish works with any text entered into a Web browser: Web-based e-mail such as Hotmail, Yahoo and Gmail, Web chat, or the social networking sites MySpace and Facebook. The Vanish prototype now works only for text, but researchers said the same technique could work for any type of data, such as digital photos.

It is technically possible to save information sent with Vanish. A recipient could print e-mail and save it, or cut and paste unencrypted text into a word-processing document, or photograph an unscrambled message. Vanish is meant to protect communication between two trusted parties, researchers say.

"Today many people pick up the phone when they want to talk with a lawyer or have a private conversation," Kohno said. "But more and more communication is happening online. Vanish is designed to give people the same privacy for e-mail and the Web that they expect for a phone conversation."

(Photo: University of Washington)

University of Washington

LOOKING DIFFERENT HELPS ANIMALS TO SURVIVE

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Sometimes the number of distinct visible forms – ‘exuberant polymorphisms’ – in a single animal population can reach double figures. But why?

Scientists at the University of York have developed computer models that may help to explain how this level of variation arises and persists. Their research is reported in the latest issue of Evolution.

A prime example of an exuberant polymorphism is the Hawaiian Happy-face Spider, which has been studied by Dr Geoff Oxford and colleagues in the University’s Department of Biology. The variations range from a common plain yellow form to rare types sporting red, black or white marks, all of which are inherited.

Dr Oxford said: “It has always been a real mystery why every population of this spider across different Hawaiian islands contains such high levels of variation. This was the starting point for our models.”

Previously scientists believed that ‘apostatic predation’ was the most likely explanation for polymorphisms. This process involves predators developing mental search images of the appearance of the most common prey, so they are more likely to overlook prey of a different appearance. A strange consequence is that looking different from others stops an individual from standing out. This results in evolutionary selection on the prey to look different from the most common form.

However, the York researchers found that apostatic selection could not explain the sheer number of distinct forms involved in the exuberant polymorphisms of some species, but that ‘dietary wariness’ could. Dietary wariness is a hesitancy of predators to consume a novel food item and a consequent reluctance to incorporate it into their regular diet. The new research suggests that a modest level of predator dietary wariness can, on its own, lead to the maintenance of large numbers distinct prey forms within a single species.

Dr Daniel Franks, of the University’s York Centre for Complex Systems Analysis, said: “A mutant prey individual that looks different from its fellows has a survival advantage because it will be unfamiliar to predators that will be reluctant to change their diet to accommodate it. Some prey species have evolved polymorphisms to deter predators by presenting them with a large number of visually novel foods.”

University of York

TINY DIAMONDS ON SANTA ROSA ISLAND GIVE EVIDENCE OF COSMIC IMPACT

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Nanosized diamonds found just a few meters below the surface of Santa Rosa Island off the coast of Santa Barbara provide strong evidence of a cosmic impact event in North America approximately 12,900 years ago, according to a new study by scientists. Their hypothesis holds that fragments of a comet struck across North America at that time.

The research, published in the Proceedings of the National Academy of Sciences (PNAS), was led by James Kennett, professor emeritus at UC Santa Barbara, and Douglas J. Kennett, first author, of the University of Oregon. The two are a father-son team. They were joined by 15 other researchers.

"The pygmy mammoth, the tiny island version of the North American mammoth, died off at this time," said James Kennett. "Since it coincides with this event, we suggest it is related." He explained that this site, with its layer containing hexagonal diamonds, is also associated with other types of diamonds and with dramatic environmental changes and wildfires. They are part of a sedimentary layer known as the Younger Dryas Boundary.

"There was a major event 12,900 years ago," said James Kennett. "It is hard to explain this assemblage of materials without a cosmic impact event and associated extensive wildfires. This hypothesis fits with the abrupt climatic cooling as recorded in ocean-drilled sediments beneath the Santa Barbara Channel. The cooling resulted when dust from the high-pressure, high-temperature, multiple impacts was lofted into the atmosphere, causing a dramatic drop in solar radiation."

The tiny diamonds were buried below four meters of sediment and they correspond with the disappearance of the Clovis culture –– the first well-established and distributed North American peoples. An estimated 35 types of mammals and 19 types of birds also became extinct in North America about this time.

"The type of diamond we have found –– lonsdaleite –– is a shock-synthesized mineral defined by its hexagonal crystalline structure," said Douglas Kennett, associate professor of anthropology at the University of Oregon. "It forms under very high temperatures and pressures consistent with a cosmic impact. These diamonds have only been found thus far in meteorites and impact craters on earth, and appear to be the strongest indicator yet of a significant cosmic impact [during Clovis]."

The diamonds were found in association with soot, which forms in extremely hot fires, and they suggest associated regional wildfires, based on nearby environmental records. Such soot and diamonds are rare in the geological record. They were found in sediment dating to massive asteroid impacts 65 million years ago in a layer widely known as the K-T Boundary, known to be associated with the extinction of dinosaurs and many other types of organisms.

(Photo: James Kennett)

UC Santa Barbara

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