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By Juli Berwald. ISNS Contributor

(ISNS)—There are ecologists who study land, and ecologists who study the ocean — but who looks up and studies the air that circles the entire planet? Until recently, not many.

Formally established just three years ago, aeroecology is the study of flying and floating organisms in the air they inhabit.

Biologist Thomas Kunz from Boston University is pioneering this new field. He notes that that the air is the only environment that moves freely, and quickly, around the entire planet.

"Aquatic environments are interrupted by land, and terrestrial environments are interrupted by water," said Kunz.

Kunz cautions that the air is an environment, not an ecosystem. Except for a few bacteria that might spend their lives in clouds, the airborne creatures require the energy from photosynthesis that occurs on land or in water.

For the first time last week, the Ecological Society of America included a session on this buoyant new discipline at its annual meeting.

Ecology On The Radar

Radars played a key role in launching the field of aeroecology. Meteorologists have long recognized that creatures flying through the radio waves scatter the signal. So, they routinely filtered out that noise to get a clearer picture of the weather.

But according to biologist Winifred Frick of the University of California, Santa Cruz, that discarded "biogunk" is just the information scientists need to observe flying animals at the scales that matter most.

Radar signals, with centimeter-long wavelengths, are the right size to reflect off creatures the size of birds, bats, and even moths. The maximum range of a radar is 288 miles, an area large enough to potentially track a foraging bat.

In the United States, a network of 159 next generation weather radars known as NEXRAD has been scanning the air every 5 minutes for the last 20 years.

Meteorologist Phillip Chilson from the University of Oklahoma has been instrumental in recovering the biological backscatter from NEXRAD archives.

"This could be one of the largest biological repositories in existence," said Chilson.

When scientists piece together a time series of NEXRAD backscatter images, they see patterns in the air on a spatial and temporal scale never before possible. Armed with the ability to visualize flying creatures, researchers are starting to look for larger ecological patterns in the air.

During the Ecological Society meeting, Frick played a movie of backscatter images in which a weather front corralled insects along its leading edge. Bats, which have a higher reflectivity and are represented by warmer colors in the images, suddenly emerge from their cave, zero in on the insect buffet, and attack along its length.

Frick analyzed the timing of bats emergence from caves and related it to climate. In a drought year bats emerge earlier in the evening than in a wet year. She suggests populations of insects increase in wet years so foraging requires less time.  

Entomologist Jason Chapman used radar and wind data to show that silver Y moths, thought to be passive passengers in wind currents, actively select favorable conditions for migration. In the springtime they wait for winds that push them northward. In the fall, they choose winds that carry them back to the south. Just how such clever decision-making by an insect is achieved, is unknown.

Beyond Radar

Aeroecologists presented an array of technologies unraveling connections between fliers and their airspace at the meeting.

Thermal imaging lets scientists track bats in the nighttime skies, a previously unfeasible task. Biologists from Israel use small GPS sensors to track the movements of Egyptian fruit bats. Bats wearing radio trackers teach researchers more about patterns of flight.

Genetic analysis of feathers helps identify the breeding and wintering grounds of songbirds. Complex mathematical models predict the movement of seeds across heterogeneous terrain.

Despite advances, questions fundamental to aeroecology remain.

"We’d like to know the biomass of what’s in the air," said Kunz.

Considering the scientific and technological effort now aimed upward, Kunz added, "I think we’ll ultimately get there."

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If you’ve ever spilled a drop of coffee on a surface, you might have noticed the curious way the color concentrates at the edges when the coffee dries. This is known as the "coffee ring effect," and recently, researchers have determined that the shape of the particles in the liquid is an important factor in creating this pattern. The research results could eventually translate into new techniques or formulations for product coatings, or better inks and paints.

This work, published in the August 18 issue of the journal Nature was performed by Arjun Yodh and colleagues at the University of Pennsylvania.

"We found that if you change the shape of the particles in the solution, the coffee ring effect goes away, and you end up with a uniform coating," said Peter Yunker, a graduate student in Yodh’s lab.

First, a little fluid dynamics: As the liquid in a droplet evaporates, the edges remain fixed, so as the volume decreases, fluid flows outward from the middle of the droplet to its edges. This flow carries particles to the edges, and round particles at the edge will pack closely. By the time all of the liquid in the droplet evaporates, most of the particles will be at the edge, producing the coffee ring effect.

Both the shape that liquid droplets take, and the way the shape changes as the droplets evaporate, is greatly influenced by surface tension at the air-liquid interface. This tension is a property of the interface, based on how the molecules in the liquid interact with one another versus the air. For example, liquids with a high surface tension, like water, may form a raised droplet, because the molecules are very attracted to one another and not so attracted to the air. In contrast, liquids with lower surface tension, like alcohols, are more likely to form flat spots instead of curved droplets.

The Yodh group found that elongated particles in a liquid behave differently than round ones because of the way they are affected by the surface tension of the air-liquid interface. The forces at work are even observable in a common breakfast cereal.

"If you make the particles elongated or ellipsoidal, they deform the air-water interface, which causes the particles to strongly attract one another. You can observe this effect in a bowl of cheerios-if there are only a few left they clump together in the middle of the bowl, due to the surface tension of the milk," explained Yunker.

This clumping changes the way the particles distribute themselves within the droplet. Even if the clumped ellipsoidal particles reach the edge of the droplet, they do not pack as closely as round particles. The loosely packed clumps eventually spread to cover the entire surface, filling it so an even coating of particles is deposited when evaporation is complete.

"This work gives us a new idea about how to make a uniform coating, relatively simply. If you change the particle shape, you can change the way a particle is deposited. You can also make mixtures. In some cases, even just a small amount of ellipsoids can change the way the particles deposit when they dry," said Yodh.

In future studies, the research team will explore drying and deposition of different types of fluids. They will also investigate different particle sizes and shapes, and the interplay of particle mixtures.

"This is an exciting scientific result with potential commercial applications, which was in part enabled by support of the Materials Research Science and Engineering Center at the University of Pennsylvania," said Mary Galvin, program director for the division of materials research at the National Science Foundation, which partially funded the research. The centers program, recently renamed Materials Research Centers and Teams, provides support for interdisciplinary materials research and education while addressing fundamental problems in science and engineering.

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By Judy Holmes, Syracuse University

Ancient fossilized clams that lived off the coast of Antarctica some 50 million years ago have a story to tell about El Niño, according to Syracuse University researcher Linda Ivany. Their story calls into question contemporary theories that predict global warming could result in a permanent El Niño state of affairs.

“The clams lived during the early Eocene, a period of time when the planet was as warm as it’s been over the last 65 million years,” says Ivany, a researcher in the Department of Earth Sciences in SU’s College of Arts and Sciences. “We used growth rings in their shells to analyze changes in year-to-year growth rate, and linked that to changes in climate that are characteristic of El Niño today.”

The research, “El Niño in the Eocene Greenhouse Recorded by Fossil Bivalves and Wood from Antarctica,” is published online in Geophysical Research Letters and is forthcoming in print.  Ivany’s research team included Thomas Brey of the Alfred Wegener Institute for Polar and Marine Research in Germany as well as researchers from Purdue University, the University of Hawai’i, and the University of Mainz, Germany. The study was funded in part by the National Science Foundation.

The El Niño phenomenon, which occurs every two to seven years, is characterized by unusually warm ocean temperatures in the eastern Equatorial Pacific. El Niño can cause torrential rainfall in Peru, devastating drought in Australia, and generally wreak havoc on global weather. El Niño is the warm phase of a large oscillation in which the surface temperature of the tropical Pacific varies, causing changes in the winds and rainfall patterns. The complete phenomenon is known as the El Niño Southern Oscillation (ENSO).  The prevailing theory predicts that rising global temperatures could cause the ENSO to collapse, resulting in permanent El Niño conditions, which could have a major impact on socioeconomic and ecological systems worldwide. 

One way to predict the future is to examine past geologic records. The species of clams Ivany’s team studied lived to be more than 100 years old during a time when the Antarctic was as warm as modern-day Virginia. Their shells provide a long, continuous record of climate during their lifespan. "Clams, like trees, respond to changes in climate by growing faster or slower,” Ivany says. “Therefore, the width of the annual growth rings correlates with environmental variables like temperature or precipitation.  We measured the distances between consecutive bands and found two-to-seven-year periodicity in them, which is typically described for El Niño."

The researchers compared the results they obtained from the clams to a similar analysis they did of tree rings from fossilized driftwood they found buried in the same sediments as the clams. “We found the same pattern,” Ivany says. “While it might sound counterintuitive, it turns out that the inter-annual climate variations seen in the tropical Pacific today are strongly teleconnected to the Antarctic.  This seems to have also been the case 50 million years ago. The good news is that despite the very warm temperatures during the Eocene, the evidence from the clams and tree rings shows that the ENSO system was still active, oscillating between normal and El Niño years. That suggests that the same will be true in our future as the planet warms up again.”

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The research identifies the sugar molecule that makes the outer coat of the egg ‘sticky’, which is vital for enabling the sperm and egg to bind together. Researchers across the world have been trying to understand what performs this task for over thirty years.

The scientists behind this study believe their work could help address some of the previously unexplained causes of human infertility and sub-fertility and be very useful for diagnosing this problem in couples who are unable to have children. It could also provide a new target for the development of natural contraceptive agents.

The international team, from the University of Missouri, the University of Hong Kong, Academia Sinica in Taiwan and Imperial College London, discovered that the sugar chain known as the sialyl-lewis-x sequence (SLeX) is highly abundant on the surface of the human egg. After experimenting with a range of synthesised sugars in the laboratory they went on to show that SLeX specifically binds sperm to an egg, and tested their findings using the outer coats of unfertilised ‘non-living’ human eggs.

"This exciting research is providing the first insights into the molecular events occurring at the very beginning of human life. The details we’ve discovered here fill in a huge gap in our knowledge of fertility and we hope they will ultimately help many of those people who currently cannot conceive," said Professor Anne Dell CBE FRS FMedSci from the Department of Life Sciences at Imperial College London, who led the team that discovered the SLeX sugars on the egg surface.

"Unravelling the composition of the sugar coat that shrouds the human egg is the culmination of many years of painstaking research by my mass spectrometry colleagues at Imperial. This endeavour was an enormously difficult task because human eggs are very tiny – about the size of a full stop – so we didn’t have much material to work with."

The World Health Organization estimates that infertility affects up to 15 percent of reproductive-aged couples worldwide and almost one in every seven couples in the UK have problems conceiving a child for various clinical reasons, many of which are still unexplained by medical science.

Lead author, Dr Poh-Choo Pang, also from the Department of Life Sciences at Imperial College London, said: "We hope that our study will open up new possibilities for understanding and addressing the fertility problems that many couples face. Although clinical treatments are still a way off, we are very excited about the new research into fertility that we hope will now be possible, building on our work."

"We first proposed a model of human sperm-binding involving SLeX-like molecules on the outer covering of the human egg in 1992. Our recent studies have now confirmed that this longstanding model is correct," said corresponding author and associate professor Gary Clark, from the University of Missouri School of Medicine. "Defining how the sperm initially recognises and then penetrates the egg’s sugar coat is important for the design of natural contraceptive agents and for unravelling  causes of previously unexplained human infertility or sub-fertility."

A sperm ‘recognises’ an egg when proteins on the head of the sperm meet and match a series of specific sugars in the egg’s outer coat. Once a successful match has been made, the outside surfaces of the sperm and egg bind together before they merge and the sperm delivers its DNA to the inside, fertilising the egg.

The authors of this new study used ultra-sensitive mass-spectrometric imaging technology to assess which molecules were most likely to be key in the binding process. They discovered that SLeX is abundantly found on the egg’s outer coat and that it is expressed at a much higher concentration than any of the other sugars that can be found on the thick transparent shell. From these results, they deduced that SLeX was most likely to be responsible for binding with proteins on the head of the sperm.

The research team in Hong Kong tested whether SLeX was the key binding sugar using the outer coats of unfertilised and non-living human eggs, obtained by informed consent from in vitro-fertilisation patients. They carefully bisected the empty coat in a delicate procedure using a tiny knife, carried out under a powerful microscope. The scientists treated one half with a chemical that prevented the SLeX sugar from binding, to see what effect this would have on a sperm’s ability to bind to the egg. When they released sperm around the bisected egg, they found that significantly fewer bound to the treated half of the egg coat than the untreated half.

Boulder, Colo.—Using data collected by NASA’s STEREO spacecraft, researchers at Southwest Research Institute and the National Solar Observatory have developed the first detailed images of solar wind structures as plasma and other particles from a coronal mass ejection (CME) traveled 93 million miles and impacted Earth.

The images from a December 2008 CME event reveal an array of dynamic interactions as the solar wind, traveling at speeds up to a million miles per hour, shifts and changes on its three-day journey to Earth, guided by the magnetic field lines that spiral out from the Sun’s surface. Observed structures include the solar wind piling up at the leading edge of a CME, voids in the interior, long thread-like structures, and rear cusps. Quiet periods show a magnetic disconnection phenomenon called a plasmoid, "puffs" that correlate with in-situ density fluctuations, and V-shaped structures centered on the current sheet—a heliospheric structure in which the polarity of the Sun’s magnetic field changes from north to south.

"For the first time, we can see directly the larger scale structures that cause blips in the solar wind impacting our spacecraft and Earth," said SwRI’s Dr. Craig DeForest, lead author of an Astrophysical Journal article released online yesterday. "There is still a great deal to be learned from these data, but they are already changing the way we think about the solar wind."

"For 30 years," said co-author Dr. Tim Howard, also of SwRI, "we have been trying to understand basic anatomy of CMEs and magnetic clouds, and how they correspond to their source structures in the solar corona. By tracking these features through the image data we can establish what parts of a space weather storm came from which parts of the solar corona, and why."

The team used a combination of image processing techniques to generate the images over a distance of more than 1 AU (astronomical unit), overcoming the greatest challenge in heliospheric imaging, that of extracting faint signals amid far brighter foreground and background signals. Small "blobs" of solar wind tracked by the team were more than 10 billion times fainter than the surface of the full Moon and 10 thousand times fainter than the starfield behind them.

"These data are like the first demonstration weather satellite images that revolutionized meteorology on Earth," said DeForest. "At a glance it is possible to see things from a satellite that cannot be extracted from the very best weather stations on the ground. But both types of data are required to understand how storms develop."

In particular, the new images reveal the shape and density of Jupiter-sized clouds of material in the so-called empty space between planets; in contrast, in-situ probes such as the WIND and ACE spacecraft reveal immense detail about the solar wind, at a single point in space.

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The world’s first view of Earth taken by a spacecraft from the vicinity of the moon. The photo was transmitted to Earth by the United States Lunar Orbiter I and received at the NASA tracking station near Madrid. This crescent of the Earth was photographed August 23, 1966 when the spacecraft was on its 16th orbit and just about to pass behind the moon.

By Ben P. Stein, Inside Science News Service

(ISNS)—You think your vacation pictures are impressive? Try to imagine what it was like 45 years ago as scientists and engineers produced the very first images of our planet from deep space.

On August 23, 1966, NASA’s Lunar Orbiter 1 took the first photo of Earth from the moon’s orbit, and it forever changed how we see our home planet.

"You’re looking at your home from this really foreign kind of desolate landscape," said Jay Friedlander, who started his NASA career 20 years ago as a photographic technician working on images including those from the Lunar Orbiter at NASA’s Goddard Space Flight Center. "It’s the first time you’re actually looking at Earth as a different kind of place," said Friedlander, currently a multimedia specialist at Goddard. 

Pictures of Earth from space had been taken before, by rockets in the 1940s, and satellites in the 1950s and 1960s. However, those pictures captured just parts of Earth, as opposed to a full-on view of the planet. But that was about to change.

In the summer of 1966, the Beatles were performing their last string of public concerts, the Baltimore Orioles were on the way to their first World Series championship, the National Organization for Women was founded, and the United States was preparing to send the first humans to the moon. But before NASA could send astronauts to our lunar neighbor, they needed to find a safe place to land. So from 1966-67, the Lunar Orbiter program dispatched unmanned reconnaissance spacecraft to orbit the moon.

"The basic idea was preparing to go to the moon for the Apollo missions," said Dave Williams, a planetary curation scientist at Goddard. According to Williams, NASA "needed high resolution pictures of the surface to make sure this is something they could land on and pick out landing sites."

NASA needed to map the moon quickly. As it turned out, they could call upon off-the-shelf technology: Boeing and Eastman Kodak had previously developed a spacecraft with an onboard camera system for the Department of Defense.

The first spacecraft, Lunar Orbiter 1, left Earth on August 10, 1966—92 hours later it was orbiting the moon.

It was like a flying photography lab, according to Friedlander.

"The camera system itself took up at least a third of the spacecraft," said Friedlander. Just about everything else, he said, "was power and propulsion."

The Lunar Orbiter camera contained dual lenses, taking photos at the same time. One lens took wide-angle images of the moon at medium resolution. A second telephoto lens took high-resolution images yielding details as small as 5 meters in size. For every swath of real estate on the moon that the medium resolution lens imaged, the high resolution lens would take three snapshots of smaller areas within that swath.

The entire camera contraption would have made Rube Goldberg proud, exposing, developing, and processing photographic film onboard a moving spacecraft, traveling around the moon constantly between hot and cold temperature extremes anywhere from approximately 27 to 3,700 miles above the lunar surface.

"This thing is going around the moon in zero gravity and developing film," said Williams. "It was an amazing achievement that they could do this."

Williams said that the camera had "these big honking reels" of 70 mm film. The film would roll through, the camera would take pictures, and then move the exposed film to an automated developer. The automated film developer contained a mix of chemicals that would develop the film using a process similar to the method used by Polaroid cameras. An electron beam would then scan each developed image before transmitting the photos back to Earth using radio signals—the same way television satellites would analog signals to TV stations.

Deployed one after the other, five Lunar Orbiter spacecraft produced a medium-detail map of 99 percent of the moon. Only in the last two years has NASA’s Lunar Reconnaissance Orbiter—still actively circling the moon—generated higher-resolution maps of the entire lunar surface.

The team, led by Dr David Wacey of the University of Western Australia and including Professor Martin Brasier of Oxford University, report the finding in the journal Nature Geoscience.

“At last we have good solid evidence for life over 3.4 billion years ago. It confirms there were bacteria at this time, living without oxygen,” says Professor Brasier of the Department of Earth Sciences at Oxford.

The Earth was still a hot, violent place at this time, with volcanic activity dominating the early Earth. The sky was cloudy and gray, keeping the heat in despite the sun being weaker than today. The water temperature of the oceans was much higher at 40-50 degrees—the temperature of a hot bath—and circulating currents were very strong. Any land masses were small, or about the size of Caribbean islands, and the tidal range was huge.

Significantly, there was very little oxygen present as there were no plants or algae yet to photosynthesize and produce oxygen. The new evidence points to early life being sulfur-based, living off and metabolizing compounds containing sulfur rather than oxygen for energy and growth.

“Such bacteria are still common today. Sulfur bacteria are found in smelly ditches, soil, hot springs, hydrothermal vents—anywhere where there’s little free oxygen and they can live off organic matter,” explains Professor Brasier.

The microfossils were found in a remote part of Western Australia called Strelley Pool. They are very well preserved between the quartz sand grains of the oldest beach or shoreline known on Earth, in some of the oldest sedimentary rocks that can be found anywhere.

“We can be very sure about the age as the rocks were formed between two volcanic successions that narrow the possible age down to a few tens of millions of years,” says Professor Brasier. “That”s very accurate indeed when the rocks are 3.4 billion years old.”

The microfossils satisfy three crucial tests that the forms seen in the rocks are biological and have not occurred through some mineralization process.

The fossils are very clearly preserved showing precise cell-like structures all of a similar size. They look like well known but much newer microfossils from 2 billion years ago, and are not odd or strained in shape.

The fossils suggest biological-like behavior. The cells are clustered in groups, are only present in appropriate habitats and are found attached to sand grains.

And crucially, they show biological metabolisms. The chemical make-up of the tiny fossilized structures is right, and crystals of pyrite (fool’s gold) associated with the microfossils are very likely to be by-products of the sulfur metabolism of these ancient cells and bacteria.

Early fossils of life on Earth has been a controversial area. In the past decade, the barriers that need to be overcome before claiming such evidence have been raised significantly, aided by new techniques for mapping the chemistry of rocks at fine scales.

In 2002, the same Oxford group suggested well-known microfossils from the Apex chert in Australia were not the preserved forms of ancient bacteria after all. They argued that the context, shape and mineralogy of the forms were all wrong for them to be of biological origin.

They believe the current fossils, found just 20 miles away, satisfy all criteria for judging such finds.

The researchers are now using the techniques and approaches they used in this study to re-examine other fossil finds that have been proposed to contain evidence for life on Earth at these extremely early times.

“We”re now making detailed comparisons with all other early microfossils, and we”re very optimistic for future finds,” says Professor Brasier.

The work also has implications for looking for life on other planets, giving an indication of what evidence for such life might look like.

Should there be life elsewhere in our solar system—on Mars or on the moons of Titan or Europa—it is likely to be similar sorts of bacteria and cells living in similar environments. So any fossils in rocks from these planets and moons ought to look like these Australian microfossils and pass the same evidence tests.

“Could these sorts of things exist on Mars? It”s just about conceivable,” says Professor Brasier. “But it would need these approaches—mapping the chemistry of any microfossils in fine detail and convincing three-dimensional images—to support any evidence for life on Mars.”

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By: Alicia Chang, AP Science Writers

WASHINGTON (AP)—The East Coast doesn’t get earthquakes often but when they do strike, there’s a whole lot more shaking going on.

The ground in the East is older, colder and more intact than the West Coast or the famous Pacific Ring of Fire. So East Coast quakes rattle an area up to 10 times larger than a similar-sized West Coast temblor.

"They tend to be more bang for the buck as far as shaking goes," said Virginia Tech geology professor James Spotila.

Tuesday’s 5.8-magnitude quake was centered in Virginia and was felt up and down the Eastern seaboard for more than 1,000 miles. There hasn’t been a quake that large on the East Coast since 1944 in New York.

While this was a rarity for the East, a 5.8 quake isn’t unusual for California, Oregon, Washington and Alaska, where one occurs about once a year. Those states have had 103 quakes 5.8 or bigger since 1900, compared to now two in the East.

The tiny island of Trinidad is more quake-prone than the East Coast, said U.S. Geological Survey seismologist Paul Earle.

"In all the years I was at FEMA, there didn’t seem to be a concern for earthquakes on the East Coast," former Federal Emergency Management Agency chief James Lee Witt said.

Because of geology, earthquakes on the coasts have different triggers and act differently in some ways. And they definitely are felt differently.

One glaring East versus West disparity: When a quake happens in California, geologists usually know what fault ruptured. Tuesday’s quake happened on an unknown fault, and it is likely to remain a mystery.

Because the quake didn’t break the surface "we may never actually map this fault from this earthquake," Earle said.

The only thing that will help scientists figure out where the break truly occurred are the aftershocks which could help highlight or outline the fault line, said Cornell University seismologist Rowena Lohman.

Most of the times, quakes occur when Earth’s floating giant plates shift, rub against or slip past each other. That’s what happens along California’s San Andreas fault when quakes happen there.

Tuesday’s thrust earthquake was far from the edge of a plate—the nearest are thousands of miles away in the mid-Atlantic or California, said seismologist David Applegate, associate director of natural hazards for the USGS in Reston, Va.

The stresses that cause these kinds of quakes come from far away and mount ever so slowly over time, even building up from the retreat of glaciers at the end of the Ice Age, he said.

Another East versus West contrast: The ground is different in the East in a way that makes the shaking travel much further, allowing people to feel the quake several states and hundreds of miles away.

The rocks in the Earth’s crust in the East are colder, older and harder, which means seismic waves travel more efficiently and over greater distances. Rocks on the West Coast are relatively young and broken up by faults.

"An intact bell rings more loudly than a cracked bell and that’s essentially what the crust is on the East Coast," USGS seismologist Lucy Jones told a news conference in Pasadena, Calif.

In the East, hurricanes are the worry far more than quakes. Former FEMA chief Witt said people on the West Coast know what to do in an earthquake: drop to the floor, cover their heads and hold on to something sturdy until the shaking stops.

That’s what USGS’s Applegate did in Virginia.

"It’s seared in our heads," said USGS seismologist Susan Hough in Pasadena. "People back East don’t get that kind of preparedness message."

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Alicia Chang contributed from Los Angeles.

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By: Bob Lewis, Associated Press

MINERAL, Va. (AP) — Tens of millions of people from Georgia to Canada were jolted Tuesday by the strongest earthquake to strike the East Coast since World War II. Three weeks before the 10th anniversary of Sept. 11, office workers poured out of New York skyscrapers and the Pentagon, relieved it was nothing more sinister than an act of nature.

There were no known deaths or serious injuries, but cracks appeared in the National Cathedral, and three capstones broke off its tower. Windows shattered and grocery stores were wrecked in Virginia, where the quake was centered. The White House and Capitol were partly evacuated.

The U.S. Geological Survey said the quake registered magnitude 5.8. By West Coast standards, that is mild. But the East Coast is not accustomed to earthquakes at all, and this one unsettled some of the nation’s biggest population centers.

In New York and Washington, people said their thoughts were of an explosion or terrorist attack. In some cases, workers in Washington mentioned the tremors in phone calls to colleagues in New York, and seconds later, the shaking reached there, too.

"We thought it was a bomb at first because everyone has 9/11 on the brain and that it’s so close to September and the 10th anniversary," said Cathy McDonald, who works in an IRS office in downtown Washington.

Hundreds of people spilled out of the federal courthouse blocks from ground zero, workers in the Empire State Building rushed into the streets, some having descended dozens of flights of stairs.

"I thought we’d been hit by an airplane," said one worker, Marty Wiesner.

Adrian Ollivierre, an accountant who was in his office on the 60th floor when the shaking began, said: "I thought I was having maybe a heart attack, and I saw everybody running. I think what it is, is the paranoia that happens from 9/11, and that’s why I’m still out here — because, I’m sorry, I’m not playing with my life."

The quake was felt as far north as Toronto, as far west as Indiana and Kentucky and as far south as Atlanta and Savannah, Ga. It was also felt on Martha’s Vineyard of Massachusetts, where President Barack Obama, who is vacationing there, was getting ready to tee off in a round of golf.

The White House said there were no reports of major damage to the nation’s infrastructure, including airports and nuclear facilities. Two nuclear reactors at the North Anna Power Station in Virginia were automatically taken off line by safety systems, said Roger Hannah, a spokesman for the U.S. Nuclear Regulatory Commission. The plant is in the same county as the quake’s epicenter, about 80 miles southwest of Washington and 40 miles northwest of Richmond, Va.

The Park Service closed all monuments and memorials on the National Mall, and ceiling tiles fell at Reagan National Airport outside Washington. Many nonessential workers in Washington were sent home for the day. The Capitol was reopened by late afternoon for people to retrieve their things.

At the Pentagon, a low rumbling built until the building itself was shaking, and people ran into the corridors of the complex. The shaking continued, to shouts of "Evacuate! Evacuate!" The main damage to the building, the largest single workspace for the federal government, came from a broken water pipe.

The National Cathedral said it had sustained "significant damage," with three capstones, each shaped like a fleur-de-lis, breaking off the main tower. Cracks appeared in the flying buttresses around the apse at the cathedral’s east end, the oldest part of the building.

"Everyone here is safe," the cathedral said on its official Twitter feed. "Please pray for the Cathedral as there has been some damage."

Around Mineral, Va., a small town close to the epicenter, people milled around in their lawns, on sidewalks and parking lots, still rattled and leery of re-entering buildings. All over town, masonry was crumpled, and there were stores with shelf contents strewn on the floor. Several display windows at businesses in the tiny heart of downtown were broken and lay in jagged shards.

Carmen Bonano, who has a 1-year-old granddaughter, sat on the porch of her family’s white-frame house, its twin brick chimneys destroyed. Her voice still quavered with fear.

By Larry O’Hanlon, ISNS Contributor

(ISNS)—Mariners may have been traveling the Aegean Sea even before the end of the last ice age, according to new evidence from researchers, in order to extract coveted volcanic rocks for pre-Bronze Age tools and weapons.

A new technique which dates obsidian—volcanic glass which can be fashioned into tools—suggests that people were mining for obsidian in Mediterranean waters and shipping the once valuable rocks from the island of Melos in modern day Greece as far back as  15,000 years ago.

"Obsidian was a precious natural rock-glass found only in Melos, some in [the modern-day Greek areas of] Antiparos and Yali," explained Nicolaos Laskaris of the University of the Aegean in Greece. "From there it was spread all over the Aegean and in the continent too through contacts of trade."

If you wanted to have sharp tools and weapons in the days before bronze, you needed places like Melos. But you also needed a boat to get there. The evidence that people were crossing over to Melos even before the end of the last ice age comes from obsidian artifacts found in the Franchthi cave on the Peloponnese peninsula in southern mainland Greece—far from the island of Melos. Previous geochemical work had already established the artifacts were from Melos, but figuring out when they were brought from the island is a trickier problem.

"They were sailors, certainly, especially in the Aegean region they followed little islands jumping like a frog reaching also Asia Minor and the Greek mainland," said Laskaris, who with his colleagues has published a paper about the discovery  in the Sept. 2011 issue of Journal of Archaeological Science. "Until now only in Franchthi cave obsidians had been found at circa 8,500 B.C. Now we prove earlier contact with coastal sites was a fact."

Laskaris and his colleagues turned to a method called obsidian hydration dating (OHD) combined with a newer technique known as secondary ion mass spectrometry of surface saturation (SIMS-SS) to determine how much water had penetrated the obsidian surfaces that were exposed to the air by prehistoric humans who were chipping the rocks to make tools and weapons.

"A freshly exposed obsidian surface contains microscopic cracks, into which water absorbs over time," explained researcher Ellery Frahm, of the University of Minnesota Twin Cities, and president-elect of the International Association for Obsidian Studies. The OHD method alone is not very reliable at dating the fractures on the rocks, because it has a couple of serious limitations, she said.

The first is the fact that it’s difficult, when looking at the rock surface through a microscope, to see and measure how deep the fuzzy water diffusion zone penetrates into a rock.

"Where do you measure along this fuzzy line? Second, the diffusion front isn’t really where it looks to be. A straw appears to bend in a glass of water due to the difference in refraction index of air and water, so the diffusion front in obsidian isn’t really where it appears to be either for the same reason," Frahm explained.

But when SIMS-SS, the new mass spectrometry technique, is added to the picture, scientists can actually quantify the water that penetrates a rock.

"SIMS can directly measure the water in obsidian over a depth," Frahm said. "A particle beam removes ions from the obsidian in extremely thin layers, it is like individually measuring the composition of each onion peel layer." That way the change in water content can be plotted with depth, revealing exactly how it changes.

Using the new SIM-SS method, Laskaris and his colleagues were able to determine that Melos obsidian artifacts were making it to the mainland earlier than previously believed. That naturally implies that people were crossing between islands very early in some unknown types of boats.

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