A new technique using near-infrared images, obtained with ESO’s 3.58-metre New Technology Telescope (NTT), allows astronomers to see through the opaque dust lanes of the giant cannibal galaxy Centaurus A, unveiling its “last meal” in unprecedented detail — a smaller spiral galaxy, currently twisted and warped. This amazing image also shows thousands of star clusters, strewn like glittering gems, churning inside Centaurus A.

Comparison between a visible-light image (left) of Centaurus A, as seen with the Wide-Field Imager on the MPG/ESO 2.2-metre telescope, and a near-infared view (right) obtained with the SOFI instrument on ESO’s New Technology Telescope, also at La Silla. (ESO)

Centaurus A (NGC 5128) is the nearest giant, elliptical galaxy, at a distance of about 11 million light-years. One of the most studied objects in the southern sky, by 1847 the unique appearance of this galaxy had already caught the attention of the famous British astronomer John Herschel, who catalogued the southern skies and made a comprehensive list of nebulae.

Herschel could not know, however, that this beautiful and spectacular appearance is due to an opaque dust lane that covers the central part of the galaxy. This dust is thought to be the remains of a cosmic merger between a giant elliptical galaxy and a smaller spiral galaxy full of dust.

Between 200 and 700 million years ago, this galaxy is indeed believed to have consumed a smaller spiral, gas-rich galaxy — the contents of which appear to be churning inside Centaurus A’s core, likely triggering new generations of stars.

First glimpses of the “leftovers” of this meal were obtained thanks to observations with the ESA Infrared Space Observatory , which revealed a 16 500 light-year-wide structure, very similar to that of a small barred galaxy. More recently, NASA’s Spitzer Space Telescope resolved this structure into a parallelogram, which can be explained as the remnant of a gas-rich spiral galaxy falling into an elliptical galaxy and becoming twisted and warped in the process. Galaxy merging is the most common mechanism to explain the formation of such giant elliptical galaxies.

The new SOFI images, obtained with the 3.58-metre New Technology Telescope at ESO’s La Silla Observatory, allow astronomers to get an even sharper view of the structure of this galaxy, completely free of obscuring dust. The original images, obtained by observing in the near-infrared through three different filters (J, H, K) were combined using a new technique that removes the dark, screening effect of the dust, providing a clear view of the centre of this galaxy.

What the astronomers found was surprising: “There is a clear ring of stars and clusters hidden behind the dust lanes, and our images provide an unprecedentedly detailed view toward it,” says Jouni Kainulainen, lead author of the paper reporting these results. “Further analysis of this structure will provide important clues on how the merging process occurred and what has been the role of star formation during it.”

The research team is excited about the possibilities this new technique opens: “These are the first steps in the development of a new technique that has the potential to trace giant clouds of gas in other galaxies at high resolution and in a cost-effective way,” explains co-author João Alves. “Knowing how these giant clouds form and evolve is to understand how stars form in galaxies.”

This image of the central parts of Centaurus A reveals the parallelogram-shaped remains of a smaller galaxy that was gulped down about 200 to 700 million years ago. The image is based on data collected with the SOFI instrument on ESO’s New Technology Telescope at La Silla.(ESO)

Looking forward to the new, planned telescopes, both on the ground and in space, “this technique is very complementary to the radio data ALMA will collect on nearby galaxies, and at the same time it poses interesting avenues of research for extragalactic stellar populations with the future European Extremely Large Telescope and the James Webb Space Telescope, as dust is omnipresent in galaxies,” says co-author Yuri Beletsky.

Previous observations done with ISAAC on the VLT (ESO 04/01) have revealed that a supermassive black hole lurks inside Centaurus A. Its mass is about 200 million times the mass of our Sun, or 50 times more massive than the one that lies at the centre of our Milky Way. In contrast to our own galaxy, the supermassive black hole in Centaurus A is continuously fed by material falling onto into it, making the giant galaxy a very active one. Centaurus A is in fact one of the brightest radio sources in the sky (hence the “A” in its name). Jets of high energy particles from the centre are also observed in radio and X-ray images.

The new image of Centaurus A is a wonderful example of how frontier science can be combined with aesthetic aspects. Fine images of Centaurus A have been obtained in the past with ESO’s Very Large Telescope (ESO PR Photo 05b/00) and with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at La Silla.

This research was presented in a paper in Astronomy and Astrophysics (vol. 502): “Uncovering the kiloparsec-scale stellar ring of NGC5128”, by J.T. Kainulainen et al.

The team is composed of J. T. Kainulainen (University of Helsinki, Finland, and MPIA, Germany), J. F. Alves (Calar Alto Observatory, Spain and University of Vienna, Austria), Y. Beletsky (ESO), J. Ascenso (Harvard-Smithsonian Center for Astrophysics, USA), J. M. Kainulainen (TKK/Department of Radio Science and Engineering, Finland), A. Amorim, J. Lima, F. D. Santos, and A. Moitinho (SIM-IDL, University of Lisbon, Portugal), R. Marques and J. Pinhão (University of Coimbra, Portugal), and J. Rebordão (INETI, Amadora, Portugal).

SOFI (Son of ISAAC) is an infrared spectro-imager attached to ESO’s 3.58-metre New Technology Telescope (NTT) and a simplified version of the Short Wavelength arm of ISAAC on the Very Large Telescope.

- ESO, The European Southern Observatory -

(CERN)

“It’s great to see beam circulating in the LHC again,” said CERN Director General Rolf Heuer. “We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way.”

The LHC circulated its first beams on 10 September 2008, but suffered a serious malfunction nine days later. A failure in an electrical connection led to serious damage, and CERN has spent over a year repairing and consolidating the machine to ensure that such an incident cannot happen again.

“The LHC is a far better understood machine than it was a year ago,” said CERN’s Director for Accelerators, Steve Myers. “We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.”

Recommissioning the LHC began in the summer, and successive milestones have regularly been passed since then. The LHC reached its operating temperature of 1.9 Kelvin, or about -271 Celsius, on 8 October. Particles were injected on 23 October, but not circulated. A beam was steered through three octants of the machine on 7 November, and circulating beams have now been re-established. The next important milestone will be low-energy collisions, expected in about a week from now. These will give the experimental collaborations their first collision data, enabling important calibration work to be carried out. This is significant, since up to now, all the data they have recorded comes from cosmic rays. Ramping the beams to high energy will follow in preparation for collisions at 7 TeV (3.5 TeV per beam) next year.

Particle physics is a global endeavour, and CERN has received support from around the world in getting the LHC up and running again.

“It’s been a herculean effort to get to where we are today,” said Myers. “I’d like to thank all those who have taken part, from CERN and from our partner institutions around the world.”

^1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

- CERN, the European Organization for Nuclear Research -

BLOOMINGTON, Ind. – Retailers beware. Some tried-and-true discounting tactics for pepping up holiday season sales can be a boon for some products — but a bust for others.

Photo by Paul Keleher

First-of-its kind research from the Indiana University Kelley School of Business confirms that certain kinds of point-of-purchase discounts can effectively attract more buyers in the short-term but for some products can tarnish sales and brand equity over time.

Researchers invited study participants — more than 100 university students — into an imaginary local grocery store where they were asked to shop “as they do in real life.” The researchers manipulated discount prices of common items and interviewed participants to determine how this might have influenced purchases. They found that for some products, placing discount messages in close proximity to discounted items was the most effective way to build sales.

Applying this knowledge to the marketplace, the researchers indicated that, for example, holiday shoppers looking for gift ideas in electronics stores would be more inclined to buy items like digital cameras flanked by “$50 Off, Limited Time Only” than they would be if they received the same message via regular mail.

Quick computing translates into sales

The study, titled “The Effects of Discount Location and Frame on Consumers’ Price Estimates,” also demonstrated that buyers are more inclined to make purchases when stores communicate discounts in ways that are instantly computable.

“Retailers should understand that most customers aren’t willing to calculate savings if they have to think too hard about the math and thus might not buy the product,” said H. Shanker Krishnan, professor of marketing at the Kelley School and co-author of the study. “Highlighting price reductions in simple, real dollar terms is a more compelling sales inducement than, say ‘25 percent off.”

However, the study noted that closely associating products with discounts can have negative implications over time.

“People come to associate certain prices with certain products,” said Krishnan. “If the discount message disappears, buyers may be put off and seek out discount prices on other, related products.”

Frequently purchased items, like music and clothing, are particularly susceptible to buyer resistance when discounts are removed. “The discounted prices are much more likely to become fixed and expected in shoppers’ minds,” said Krishnan.

On the other hand, the study showed that less frequently purchased items, like TVs, may be more immune to consumer price expectations. “The lifespan of durable items is such that shoppers forget what they last paid for them,” he said.

Luxury brands are special case

Then there is the issue of protecting brand equity. The study pointed out that point-of-purchase discounting requires a strategic, highly selective approach to ensure that certain products maintain their long-term sales potential.

H. Shanker Krishnan (Indiana University)

“It is particularly important that shoppers don’t come to associate luxury items with lower prices,” Krishnan said. “Otherwise, they’ll experience severe sticker-shock their next go-around — and brand loyalty can suffer.”

For luxury brands, the best bet might be to offer discounts via percentages and to physically separate the discount message from the product by using coupons, ads, general in-store promotions and other tactics. The price reductions may have a less telling, short-term impact on sales, but the brand equity will be protected.

Overall, said Krishnan, discounting can work very favorably for retailers if they make the effort to understand the complexities and make knowledgeable decisions.

“This seems like common sense,” he said, “but so often you see retailers seeking to maximize short-term sales while shooting themselves in the foot down the road.”

The study appeared in the September issue of Journal of Retailing. It was coauthored by Devon DelVecchio at Miami University in Ohio and Arun Lakshmanan at University of Buffalo, SUNY.

Indiana University

Slice of ice core from Berkner Island, depth 120m. Trapped air bubbles (an archive of the past atmosphere) are visible in the ice.

Previous analysis of ice cores has shown that the climate consists of ice ages and warmer interglacial periods roughly every 100,000 years. This new investigation shows temperature ‘spikes’ within some of the interglacial periods over the last 340,000 years. This suggests Antarctic temperature shows a high level of sensitivity to greenhouse gases at levels similar to those found today.

Lead author Louise Sime of British Antarctic Survey said, “We didn’t expect to see such warm temperatures, and we don’t yet know in detail what caused them. But they indicate that Antarctica’s climate may have undergone rapid shifts during past periods of high CO₂.”

During the last warm period, about 125,000 years ago, sea level was around 5 metres higher than today. Ice core scientist Eric Wolff of British Antarctic Survey is a world-leading expert on past climate. He said, “If we can pin down how much warmer temperatures were in Antarctica and Greenland at this time, then we can test predictions of how melting of the large ice sheets may contribute to sea level rise.”

The Paper: Evidence for warmer interglacials in East Antarctic ice cores by Louise C. Sime, Eric W. Wolff, Kevin I. C. Oliver and Julia C. Tindall is published online this week in the journal Nature.

By the British Antarctic Survey (BAS) Press Office

The researchers linked many powerful computer systems together to analyze enormous amounts of genetic data collected from all publicly available isolated strains of the H5N1 virus – the cause of avian flu. They then developed a new Web-based application that will allow health officials and the public visualize how the virus moved across the globe using Google Earth.

The green lines on this interactive map represent how pandemic influenza (H1N1) has moved from points in the United States to geographic locations across the globe. Screenshot taken using Google Earth.

The resulting visualizations, based on results of the data analysis, represent the most comprehensive map to date of how avian flu has been transmitted among sites in Asia, Africa and Europe.

But underlying those findings is a new way of analyzing genetic data that generates more complete information about the flu’s spread. The method, combined with the increasing availability of sequenced genomes of isolated flu strains, is expected to help public health officials make more knowledgeable predictions about how the H1N1 flu pandemic will evolve.

“We are taking into account more data but at the same time, we’re making simpler visualizations, allowing users to choose what they want to see,” said Daniel Janies, associate professor of biomedical informatics at Ohio State and senior author of the study.

“We’ve created an environment where people can avail themselves of flu information specific to their region of the world or their area of interest. We waded through all of the complexities so people in the public health realm who want to determine how a flu virus got from point A to point B can find that out, and we’ll have better public health outcomes as a result.”

The visualizations and application are available online at http://routemap.osu.edu.

The research appears online in the journal Cladistics.

The research environment has changed dramatically since 1997, when an avian flu outbreak in Hong Kong alerted health officials to its dangers to humans, Janies noted. The technology behind the Human Genome Project has improved to enable the rapid sequencing of numerous genomes, and avian flu’s broad transmission has encouraged scientists to place viral sequence data into the public domain. At the same time, computational power has continued to expand.

Janies and colleagues obtained high-quality avian flu sequences contained in the repositories at the National Institutes of Health’s GenBank and the Global Initiative on Sharing Avian Influenza Data (GISAID). They then focused on studying two genes within the virus whose mutations are believed to have the most impact on H5N1 behavior: hemagglutinin, which produces the protein that recognizes the host cell receptor, and neuraminidase, an enzyme that helps the virus escape one cell so it can enter other cells.

The researchers used 1,646 sequences of hemagglutinin and 1,335 of neuraminidase in this study.

Biologists construct what are called phylogenetic trees to trace evolutionary relationships among species or strains believed to share a common ancestor. These trees’ branching diagrams can be designed to track similarities in physical characteristics, for example, in the study of dinosaurs, for which genetic data cannot be easily recovered. Or, in the study of influenza, the trees can show how viral strains are related based on shared mutations.

In the past, scientists – including Janies – have selected a single phylogenetic tree to represent related viruses that share mutations. But in this paper, the researchers used the power of supercomputers to generate millions of trees representing relationships among these thousands of viruses. They then picked a pool of thousands of high-quality trees based on a scoring system in the bioinformatics field to use in their analysis of disease transmission.

The scientists then asked of these trees – what are the geographic connections between the isolated viral strains?

These resulting diagrams were then used as the basis for an interactive map that traces the genetic, geographic and evolutionary history of avian influenza over 12 years. The highly pathogenic lineage of avian flu that crossed Asia and Africa can be traced to an isolate taken from a goose in 1996. Little genetic data is available for H5N1 viruses isolated before that.

To avoid creating a complex map that looks like “spaghetti thrown on the screen,” Janies and colleagues also simplified the map’s design. Green lines represent transmission pathways most strongly supported by the research findings. Yellow lines indicate less certainty. Lines also are colored differently depending on whether they indicate an incoming or outgoing virus from a specific location. And users can search for specific transmission routes rather than seeing all transmission events on the map at once.

The maps represent scientists’ best approximation of avian flu transmission based on the information available, Janies explained. Without access to every complete genome of every flu virus that ever infected a bird or human, researchers can never fully track evolutionary relationships, genetic histories and specific locations of each outgoing and incoming viral transmission.

Daniel Janies

“Collect and share as much data as possible and let the data tell the story,” he said. “We’re honest about the uncertainty our results may have – but even with partial data, we can infer much about a virus in an area based on its sources.”

The method has already been applied to studies of the H1N1 flu currently infecting millions of people in the United States. International cooperation spearheaded by the NIH, GISAID and the Centers for Disease Control and Prevention has resulted in ready availability of H1N1 sequences for study.

“With what we have so far, we can see the spread of H1N1 out of the United States and all over the world. There is a different dynamic, in that this is a virus carried by humans, who are cosmopolitan and moving both ways,” Janies said. “It’s also a virus that has been transmitted all over the world in a matter of months, and it’s still similar to its ancestors.”

H5N1, on the other hand, has been creeping across Asia and into Europe and Africa for more than a decade and picked up mutations along the way, he noted. While H1N1 has spread more quickly, it is far less deadly to humans than H5N1 – meaning it is still useful for the world to keep an eye on avian flu, Janies said.

His group’s visualizations will help make that possible.

The computing power used in this study was supplied by the Ohio Supercomputer Center and the Ohio State University Medical Center. The research is funded by the U.S. Army Research Laboratory and Office, Ohio State’s Department of Biomedical Informatics and the Mathematical Biosciences Institute (MBI) at Ohio State.

Janies conducted the work with Rasmus Hovmöller, Boyan Alexandrov and Jori Hardman of Ohio State’s Department of Biomedical Informatics. Hovmöller is also an investigator in the MBI.

Written by Emily Caldwell – Ohio State University

Screen shot from TowerMadness, a 3D iPhone game created by UC San Diego computer science students, past and present. (University of California, San Diego)

Three current and former UC San Diego computer science students created TowerMadness, the cheat-resistant 3D game which challenges players to repel alien onslaughts by constructing defensive towers in strategic locations. A multi-touch interface allows TowerMadness players to zoom in and around the visually-detailed 3D action.

The game’s cheat resistance is rooted in a unique online replay feature. In particular, the developers built a proprietary replay verification system that automatically replays high-scoring games and checks that players legitimately scored as many points as their devices are reporting.

“The replays allow us to verify that the games submitted to our servers are genuine, keeping the online global scoring fair and fun for everyone,” said Iman Mostafavi, a computer science Ph.D. student at the UC San Diego Jacobs School of Engineering and one of the game’s three developers.

Each replay is a tamper-resistant, highly compact recording of a player’s actions over the course of a game.

“We’ve already thwarted several attempts at cheating,” said co-developer Volker Schönefeld, a former visiting graduate student to UC San Diego’s computer science department who is completing his doctoral degree at RWTH Aachen University, in Aachen Germany.

The replays are significantly smaller than a video of the same length and can be transmitted over the Internet in seconds.

TowerMadness’ replay features grew out of the technology Schönefeld pioneered in 2003 for Waaagh!TV, his e-Sports broadcasting company. Waaagh!TV develops software that allows thousands of users to simultaneously watch live online matches of the popular computer game Warcraft III.

In addition to cheat resistance, the replay feature allows TowerMadness players to show off their strategies and learn new ones by watching completed games. Anyone with a copy of TowerMadness can watch the replays.

The game includes additional online features supported by Google’s App Engine cloud computing platform. Players can compete globally for high scores, download free additional game content, and share their games on Twitter and Facebook.

Schönefeld and Mostafavi, along with Arash Keshmirian, a UC San Diego computer science BS/MS alumnus, began developing TowerMadness in their spare time shortly after Schönefeld’s first visit to the department in 2008. “With our shared interest in building apps for the platform, combined with many years of experience in developing computer graphics software, I knew we could push the iPhone’s capabilities to a level where only experienced developers could compete. This would be an important differentiator in an already crowded marketplace,” said Keshmirian, who is now an entrepreneur and consultant based in Silicon Valley.

On May 15, 2009, after nearly six months of development, TowerMadness scored a preview feature on the holy grail of iPhone gaming Touch Arcade, which fueled widespread anticipation for the release. The game went live on May 23rd, and news and reviews of the game began appearing on numerous blogs, web sites, and media around the world. Several days later, TowerMadness won an award from the prominent mobile gaming web site Pocket Gamer.

Another big visibility boost came when Apple picked TowerMadness for a prized high-profile spot on the iTunes App Store itself—the Featured Apps section.

“In a sea of over 50,000 apps, visibility is paramount. Being put in the spotlight by Apple early on has been a tremendous boon,” according to the developers. Only a month since its launch, players have submitted well over 150,000 rounds of TowerMadness to the online leaderboards.

Much of the cutting-edge 3D graphics, programming and gaming know-how that is helping to make TowerMadness popular was developed, strengthened or nurtured at UC San Diego. The UCSD Department of Computer Science and Engineering (CSE) and the UC San Diego Division of Calit2 (California Institute of Telecommunications and Information Technology) played particularly important roles.

The trio’s company, Limbic Software, plans to continue releasing downloadable content and updates for TowerMadness. Hoping to bring the excitement of competitive gaming to mobile gamers, the game will soon allow players to compete for real prizes. The team is also working hard towards the release of their upcoming second game.

The TowerMadness web site http://www.towermadness.com features more information, screenshots, and videos.

Before developing TowerMadness, Iman Mostafavi worked on various visualization projects at Calit2, including some that matured into StarCAVE, a five-sided virtual reality room where scientific models and animations are projected in stereo on 360-degree screens surrounding the viewer, and onto the floor.

Mostafavi also develops algorithms for improving the quality and utility of 3D models that represent biological data gleaned from biological images taken by electron microscopes. Mostafavi performs this work at the National Center for Microscopy and Imaging Research (NCMIR) at UC San Diego, which develops state-of-the-art 3D imaging and analysis technologies to help biomedical researchers understand biological structure and function relationships in cells and tissues.

Mostafavi also collaborated on UC San Diego interactive artwork, shown at SIGGRAPH 2007, that explored new ways of representing nature in the era of metagenomics.

At UC San Diego, Keshmirian developed physically-based simulations of light transport to produce realistic images of various phenomena, such as light passing through plant leaves. Keshmirian’s 2008 thesis, with advisor, computer science professor Henrik Wan Jensen, describes a new, and significantly more complete model for the simulation of light within camera lenses. The techniques can be used to artificially produce many of the effects observed when taking photographic pictures in the real world, thereby enhancing simulated images. Keshmirian was also the editor of the photography department at the UCSD Guardian, the university’s official student-run newspaper.

“Having the opportunity to take two completely different perspectives on photography: scientific and artistic, was a real boon for both my research and my art,” remarks Keshmirian. Keshmirian’s creative eye helped him develop the quirky-cute visual style for TowerMadness.

During his six month stay at the computer science department at UC San Diego, Schönefeld worked on his Master’s thesis, the topic of which is the mathematical analysis of physically-based simulation of light as it travels through a virtual scene. Schönefeld performed this research under the supervision of computer science professor Henrik Wann Jensen.

TowerMadness Gameplay: Tutorial and Easy Map

By Daniel Kane – University of California, San Diego

An illustration of two proteins involved in DNA repair by artist Amy VanDonsel

Using yeast cells, the scientists studied protein molecules that have an important role in homologous recombination, which is one way that cells repair breaks in the DNA double helix. The process in yeast is similar to that in humans and other organisms.

Earlier research had established that a protein molecule named Srs2 regulates homologous recombination by counteracting the work of another protein, Rad51. Reporting in the July 10 issue of the journal Molecular Cell, the research team reveals the mechanism of how Srs2 removes Rad51 from DNA and thereby prevents it from making repairs to broken strands.

“Our findings may make it possible to uncover ways to augment the effect of DNA-damaging agents that are used for cancer chemotherapy,” says senior author Tom Ellenberger, D.V.M, Ph.D., the Raymond H. Wittcoff Professor and head of the Department of Biochemistry and Molecular Biophysics. “Many chemotherapeutic agents work by causing DNA damage in cancer cells, leading to their death, and tumors can become resistant to chemotherapy by using DNA repair mechanisms to keep the cells alive. Drugs that inhibit the DNA repair process could help increase the efficiency of chemotherapeutic agents.”

Ellenberger is also co-director of the Pharmacology Core at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University. The facility aids in the development of anti-cancer agents.

Srs2 is a helicase molecule — a motor protein that’s able to walk or slide along a strand of DNA and remove other proteins from DNA or separate the two strands of the twisted double helix. For studies of Srs2, Ellenberger’s laboratory collaborated with Timothy Lohman, Ph.D., the Marvin A. Brennecke Professor of Biochemistry and Molecular Biophysics, a prominent expert in the biochemistry of motor proteins like Srs2.

Rad51’s job in the cell is to promote the exchange of sequences between two related DNA molecules, which can be used to repair breaks in DNA where both strands of the double helix are compromised. As a DNA matchmaker, Rad51 forms long filaments on DNA. Srs2 can remove these to prevent unwanted exchanges of DNA sequences. Without Srs2, cells lose their ability to maintain the normal structure of chromosomes, and DNA sequences become shuffled.

The biochemists found that Srs2 possesses a small arm that interacts with Rad51 and triggers a chemical reaction within the Rad51 protein causing it to fall off the DNA.

“Scientists had assumed that as Srs2 moved along the DNA strand, it just pushed off everything in its path,” says lead author Edwin Antony, Ph.D., a postdoctoral research associate in biochemistry and molecular biophysics. “This isn’t the case — we showed that Srs2 has a specialized structure that allows it to interact specifically with Rad51.”

This finding shows how a motor protein like Srs2 can perform the specialized task of remodeling a protein-DNA complex without interference by other similar helicases, he adds.

Because they now know more precisely the nature of this interaction between Srs2 and Rad51, the researchers can narrow their search for drugs that will block DNA repair by Rad51. This type of drug could make a lower dose of a DNA-damaging drug effective in treating cancer.

The research team is now trying to identify the Srs2 homologue in human cells and will study its structure in combination with Rad51. That will allow a more rational approach to understanding how cells cope with DNA damage and how some tumors evade cancer therapeutics, they say.

“In the long-term, my laboratory will look for drug-like molecules that influence this interaction,” Ellenberger says. “We are using the Chemical Genetics Screening Center here at the University (http://htc.wustl.edu). It has vast libraries of molecules that may have the activity we want. Edwin’s work on Srs2 and Rad51 will allow us to develop an assay to screen for agents that augment or supersede Srs2’s interference with DNA repair.”

Antony E, Tomko EJ, Xiao Q, Krejci L, Lohman TM, Ellenberger T. Srs2 disassembles Rad51 filaments by a protein-protein interaction triggering ATP turnover and dissociation of Rad51 from DNA. Molecular Cell. 2009;35(1):105-115.

Funding from the National Institutes of Health and the Young Scientist Program at Washington University supported this research.

Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Siteman Cancer Center is the only federally designated Comprehensive Cancer Center within a 240-mile radius of St. Louis. Siteman Cancer Center is composed of the combined cancer research and treatment programs of Barnes-Jewish Hospital and Washington University School of Medicine. Siteman has satellite locations in West County and St. Peters, in addition to its full-service facility at Washington University Medical Center on South Kingshighway.

By Gwen Ericson – Washington University in St. Louis, School of Medicine

Atlanta —Tropical Cyclone Nargis made landfall in the Asian nation of Myanmar on May 2, 2008, causing the worst natural disaster in the country’s recorded history—with a death toll that may have exceeded 138,000. In the July 2009 issue of the journal Nature Geoscience, researchers report on a field survey done three months after the disaster to document the extent of the flooding and resulting damage.

Cyclone Nargis caused significant coastal erosion and land loss, shown here at Aya near the Ayeyarwady estuary in Myanmar. At top left is the golden Buddhist stupa, which was originally built on dry land. (Photo: Hermann Fritz)

The information—which may be the first reliable measurements of cyclone damage in the area—could lead to development of computer models for predicting how future storms may impact the geologically complex Ayeyarwady River delta. Those models could be the basis for planning, construction and education that would dramatically reduce future loss of life.

Among the findings of the study: the cyclone created a storm surge as much as five meters high—topped by two-meter storm waves—that together inundated areas as much as 50 kilometers inland. Fatality rates reached 80 percent in the hardest-hit villages, and an estimated 2.5 million people in the area lived in flood-prone homes less than 10 feet above sea level.

“The recorded high water marks serve as benchmarking for numerical models for the complex hydraulic response of the giant Ayeyarwady delta,” noted Hermann M. Fritz, an associate professor in the School of Civil and Environmental Engineering at the Georgia Institute of Technology. “Ongoing numerical simulations will allow us to determine flood zones and vulnerabilities for future cyclone scenarios. Based on those, evacuation scenarios and evaluation plans will be derived in collaboration with international partners and the Myanmar government.”

Already, a local non-governmental organization in the nation has developed a cyclone education program to raise awareness among residents, said Fritz, who was the only international scientist leading a team that surveyed 150 kilometers of the country’s coastline during a two-week period August 9-23, 2008.

“The aim of our project was to document the extent of the flooding and associated damage in the delta,” Fritz explained. “Field surveys in the immediate aftermath of major disasters focus on perishable data, which would otherwise be lost forever—such as infrastructure damage prior to repair and reconstruction.”

In the flood zone, for instance, the researchers searched for evidence of water marks on buildings, scars on trees and rafted debris as indicators of the maximum water height.

“Nargis washed away entire settlements, often without leaving a single structure standing, which forced us to focus on evidence left on large trees,” added Fritz, who has studied other natural disasters in Asia, Africa and the United States. “High water marks were photographed and located using global positioning system instruments. Transects from the nearest beach or waterway to the high water marks were recorded with a laser range finder.”

The survey team documented soil erosion of as much as one meter vertically and more than 100 meters horizontally. Highlighting the loss of land was a golden Buddhist stupa—originally constructed on dry land—that was left 150 meters offshore following the storm. Cyclone Nargis also scoured several drinking water wells, leaving them in the beach surf zone—and depriving survivors of safe water supplies.

While the storm surge and waves weren’t unusually high, the impact may have been worsened by the lack of nearby high ground for evacuation and loss of coastal mangrove forests that could have slowed the storm waves, Fritz said. Structures in the area were not built to survive cyclones, and there was no evacuation plan for the area—where people had no previous experience with such storms.

Rafted debris in trees showed how high the flood waters reached during Cyclone Nargis in Myanmar. (Photo: Hermann Fritz)

Those finding point to recommendations, including implementation of a cyclone education program, development of flood and vulnerability maps, construction of cyclone-safe buildings to serve as shelters, implementation of an improved warning system, and planning for evacuation, Fritz said. Partial reconstruction of the mangroves that had been removed for agriculture and fuel could also help protect the coastline.

The expedition’s itinerary was planned based on unofficial damage reports, physical storm and cyclone track data, satellite imagery, numerical model benchmark requirements and experience gained in surveying other disasters. The group traveled to the country by cargo boat and did most surveying from the vessel.

The research was in part supported by the Pyoe Pin Programme of the Department for International Development in the United Kingdom. The program is also sponsoring detailed modeling and a follow up study being done at Georgia Tech by Fritz and Christopher Blount, one of his doctoral students.

A Category 4 storm, Nargis was the eighth deadliest cyclone recorded worldwide. It is one of seven tropical cyclones generated in the Bay of Bengal that had death tolls in excess of 100,000. With damage estimated at more than $10 billion, the storm is the most destructive ever recorded in the Indian Ocean.

Fritz hopes the work done by the survey team—which also included Swe Thwin of the Myanmar Coastal Conservation Society and Moe Kyaw and Nyein Chan of the Mingalar Myanmar NGO—will ultimately help reduce the human cost of major cyclones.

“In the 21st century with modern communication and all that has been learned about cyclones in the Bay of Bengal, there is no need for 138,000 people to be killed by a storm like this,” Fritz said. “With adequate planning, education and shelters, it should be possible to reduce fatality rates from future cyclones by at least one order of magnitude.”

Related Links

• School of Civil and Environmental Engineering
• Hermann Fritz

By John Toon- Georgia Institute of Technology – Georgia Tech

Pioneer-Venus visible-light image, and Magellan radar view of Venus. Credit: NASA/JPL/RPIF/DLR.

“Carrying out these observations was a great challenge, as SCIAMACHY was not actually designed for such measurements,” Dr. Manfred Gottwald, responsible for SCIAMACHY at the DLR Remote Sensing Technology Institute (Institut für Methodik der Fernerkundung; IMF), said. “We were surprised how excellently everything worked despite that,” his colleague at the institute, Dr. Sanders Slijkhuis, the specialist responsible for calibrating the instrument, added.

SCIAMACHY on Envisat, Venus Express and COROT complement one another

The Venus observations by SCIAMACHY are useful in two respects. On the one hand, they support the in-situ measurements by the Venus Express space probe of the European Space Agency (ESA), which has been orbiting our neighbouring planet since 2006. Venus Express is studying the dense atmosphere of Venus with great precision using the SPICAV and VIRTIS spectrometers. SCIAMACHY and Venus Express are observing Venus under different viewing geometries and lighting conditions, so that their results complement one another well. In addition, SCIAMACHY’s Venus observations are a further test of the way that an Earth-like planet presents itself spectrally when observed from a great distance.

Since the first extra-solar planets – that is, planets orbiting stars other than our Sun – were discovered in the mid-1990s, the search for Earth-like companions of stars similar to the Sun, in other words a ’second Earth’, has been one of the great challenges in astronomy. Currently, however, most of the so-called exoplanets that have been found are giant gas planets rather like Jupiter. In 2008, researchers succeeded for the first time in discovering a possible Earth-like exoplanet using the CoRoT (Convection, Rotation and Planetary Transits) space telescope, a project in which the DLR is also involved (see article CoRoT discovers extrasolar rocky planets in the right column). But in the near future, small Earth-like planets could also come within reach using improved telescopes. However, they will always appear as small dots due to the enormous distances involved. The spectral analysis of the central star’s light when scattered by the exoplanets and their own thermal radiation emissions could provide information as to whether they might be suitable for harbouring life. Hence, observations of the known planets in our solar system provide an excellent experimental environment for gaining experience with regard to the interpretation of spectral signatures of Earth-like bodies.

Earth observation satellite ENVISAT. Credit: ESA.

DLR planetary researchers pleased about interdisciplinary approach

The observations of Venus, with its hot and hostile environment – surrounded by a dense carbon dioxide atmosphere – can provide outstanding comparative data in our immediate cosmic neighbourhood for the analysis of the atmosphere of exoplanets. “As planetary researchers, we are of course very pleased about these additional measurements from a mission whose aim is actually Earth observation,” Prof. Tilman Spohn, Director of the DLR Institute of Planetary Research (Institut für Planetenforschung) in Berlin-Adlershof, says. He adds: “It is excellent that these data from SCIAMACHY were picked up. They help us to evaluate the data supplied by our experiments on the planetary missions.”

“We are very impressed by the SCIAMACHY observations,” Prof. Heike Rauer, also from the DLR Institute of Planetary Research and the leader of the project through which DLR is involved in the search for exoplanets with CoRoT, said happily. “The new results illustrate excellently what atmospheric signatures would be expected if a Venus-like exoplanet were discovered.” Future satellites could then search for signs of a biosphere, the zone where organisms can live, on such planets. Scientists from the DLR Remote Sensing Technology Institute in Oberpfaffenhofen have been working with the researchers from the DLR Institute of Planetary Research in Berlin-Adlershof for some time in the search for what are known as ‘biomarkers’ – components in the atmosphere or on the surface of planets that have been created through the metabolic activity of life forms.

The intention is to make further use of the SCIAMACHY measurements in the ‘Planetary Evolution and Life’ Helmholtz Alliance. This international research network is investigating the question, among other things, as to what conditions must prevail on a planet in order for life to develop. Here, the data offer a realistic background for modelling the radiation transport in the atmospheres of Earth-like planets.

Additional measurements of spectra in various phases of Venus are planned with SCIAMACHY. In addition, studies are underway as to how the other bright planets of our solar system, Mars, Jupiter and Saturn, can also be used as extraterrestrial objects of investigation.

Venus – bright, small and “difficult to measure”

Relative positions of Earth and Venus, March and June 2009. Credit: DLR/NASA-JPL Solar System Simulator.

Venus, with its 12 100-kilometre diameter, is almost as large as our home planet.  Seen from Earth, it appears as the brightest celestial body after the Sun and Moon – but with a subtended angle of less than one minute of arc (one sixtieth of a degree) it looks relatively small. As a consequence, in order to keep this small ‘Venusian disc’ in SCIAMACHY’s field of view long enough to perform the observations, the instrument configuration had to be changed substantially. Due to the arrangement of SCIAMACHY’s observation windows, Venus only appears above Earth’s horizon briefly after rising – a process which is repeated 14 to 15 times per day as a result of Envisat’s orbit of the Earth. Precise planning as well as chronologically exact measurements finally enabled the derivation of Venus spectra on the basis of the solar radiation reflected and scattered by the planet’s atmosphere. Both in March and in June 2009 SCIAMACHY recorded Venus spectra during several orbits of Earth (see PDF download ‘SCIAMACHY spectra of Venus’ in the right column).

As an inner planet, Venus moves faster around the Sun than Earth. Therefore, the relative positions of Earth, Venus and Sun changed significantly between March and June 2009 (see image). In March 2009, Venus was close to what is known as its ‘inferior conjunction’, directly between Earth and the Sun. Seen from Earth, it presented mainly its dark side and only a thin crescent of the sunlit planetary disc was visible. At this time, the distance of Venus from Earth was only 43 million kilometres. In June 2009, by contrast, the Sun, Venus and Earth formed an almost right-angled triangle. Although the distance between Venus and Earth had grown to 127 million kilometres, more than 50 percent of Venus’ disc now lay in sunlight when seen from Earth.

SCIAMACHY on Envisat

ESA’s Envisat Earth observation satellite has been orbiting Earth since 2002 and supplies valuable information about the state of Earth. The SCIAMACHY atmospheric instrument on board Envisat, designed under the lead management of  DLR together with Dutch and Belgian partners, measures the solar radiation scattered back from Earth’s surface and atmosphere from the ultraviolet to the near-infrared parts of the spectrum. These measurements can be used to determine the atmospheric concentration of many different trace gases, which are important with regard to air quality, the greenhouse effect and ozone chemistry. SCIAMACHY is the first and currently the only satellite instrument in the world to carry out measurements of such complexity. The project is managed by DLR and the Netherlands Space Office (NSO). The Institute of Remote Sensing and Environmental Physics (IFE/IUP) of the University of Bremen is responsible for the scientific management the project.

German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR)