What Caused Ancient Upheaval to Australian Landscape?

Between about 45,000 and 50,000 years ago, Australia experienced three radical changes. The continent was once home to a menagerie of giant creatures, or megafauna, such as marsupial versions of lions, rhino-size wombats, giant kangaroos and flightless birds, but about 90 percent of that megafauna disappeared during this time. A major, relatively brief shift in plant life ? from grasses to trees ? occurred during this period as well. And last but not least, humans colonized Australia during this period.

Because the arrival of humans coincided with dramatic changes in the animal and plant life of Australia, many scientists have speculated that humans impacted the continent's flora and fauna. For instance, humans may have burned the land, perhaps accidentally, or to concentrate game animals. This shift in plant life would have driven these plant-dependent herbivores ?as well as the carnivores that preyed on those herbivores ?to extinction.

However, other scientists have suggested different explanations for these changes. For instance, the extinction of many plant-eating megafauna in Australia could have triggered major upsets when it came to which plants dominated the continent.

To shed light on this mystery, a team of investigators have reconstructed past changes in vegetation by looking at ancient sediment from the Murray Canyons Group region offshore southern Australia. This material was deposited by a river system that once covered more than 425,000 square miles (1.1 million square kilometers) of southeastern Australia ?an area that was home to many of the megafauna that became extinct. What they found suggests that fire-wielding humans weren't to blame for the drastic shift in the makeup of the landscape. [Wipe Out: History's Most Mysterious Extinctions]

Carbon signatures

The scientists focused on isotopes of carbon in plant waxes found in ancient soils and sediments. Carbon isotopes differ in how many neutrons they possess in their atomic nuclei ? carbon-12 has six neutrons, while carbon-13 has seven. (Both have six protons.)

The kinds of grasses that dominate northern Australia today have adapted to warmer, dryer conditions and mostly practice a kind of photosynthesis known as C4, which uses both carbon-12 and the heavier carbon-13 isotope. On the other hand, trees and shrubs that have adapted to cooler, wetter conditions depend on a type of photosynthesis known as C3, which also takes up carbon-12 and carbon-13 but prefers carbon-12. By analyzing the ratios of these different carbon isotopes within plant waxes, the researchers could infer what plants dominated the region at different times in the past.

The scientists also looked for an organic compound known as levoglucosan. This molecule is exclusively generated during the burning of land vegetation, so its presence would bolster the idea that humans changed the landscape with fire.

The results of the study showed that about 44,000 to 58,000 years ago, C4 plants apparently dominated the region much as they do today, making up 60 to 70 percent of the vegetation there. However, by 43,000 years ago, C4 plants made up only 40 percent of the vegetation there. There was a matching rise in C3 plants that lasted for about 5,000 years.

Which came first?

This shift in plant life probably came after the megafauna extinction about 44,000 to 49,000 years ago, not before it, the study researchers suggest. This may rule out the human use of fire as the cause of those mass deaths.

Instead, this discovery hints that an extinction of megafauna herbivores that normally browsed on C3 plants, allowing trees and shrubs to rise in dominance. This, in turn, led more fire-prone vegetation to build up in the Australian landscape, the researchers said.

"In 150,000 years of climate change in southeastern Australia, lots of changes in the vegetation took place, but none was so strong and abrupt as the change 43,000 years ago caused by the extinction," researcher Stefan Schouten, a geochemist at the NIOZ Royal Netherlands Institute for Sea Research, told LiveScience.

Scientists still aren't certain what caused the extinction of Australia's megafauna herbivores in the first place. Humans remain one potential culprit for the megafauna extinction ? they did arrive on the continent about 45,000 to 54,000 years ago, before this shift in the region's plant life, which suggests they could have caused the demise of the megafauna that led to the plant upheaval.

The scientists detailed their findings online June 30 in the journal Nature Geoscience.

Follow us @livescience, Facebook & Google+. Original article on LiveScience.com.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Source: http://news.yahoo.com/caused-ancient-upheaval-australian-landscape-121642608.html

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Indexes edge up as Fed slowdown fears ebb

NEW YORK (AP) ? Stocks are ending slightly higher after a report of tepid U.S. economic growth raised expectations that the Federal Reserve will continue its stimulus program.

The government lowered its estimate for growth in the first three months of the year to 2.4 percent from 2.5 percent.

Stocks slid last week on concerns that the Fed might slow its bond purchases.

The Dow Jones industrial average rose 21 points to 15,324 Thursday, or 0.1 percent. The Dow was up 95 points in the afternoon, then faded in the last hour.

The Standard & Poor?s 500 rose six to 1,654, or 0.4 percent. The Nasdaq rose 23 points to 3,491.

Three stocks rose for every two that fell on the New York Stock Exchange. Volume was average at 3.5 billion shares.

Source: http://feeds.salon.com/salon/index

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Samsung Galaxy Mega 6.3 review: one giant smartphone for mankind

Godzilla, Frankenstein's monster and Bigfoot are mythical creatures that don't exist (although you might dispute the latter). But now, an equally beastly smartphone -- one seemingly designed specifically for them -- is available to buy. The Samsung Galaxy Mega is a 6.3-inch woolly mammoth of a handset, and it reigns as the largest of its kind, even if only for a brief period of time; the title will soon be taken over by the Sony Xperia ZU once it hits the market. We were curious to see how a phone of its size would hold out during regular use, so our friends at Negri Electronics -- an online retailer which currently sells the Mega for $570 or $600 (8GB and 16GB, respectively) -- were kind enough to let us take one for a test drive for a few days. Is the phone's magnitude a benefit or hindrance to the user experience? Is it even worth considering if you don't need the largest possible screen? Find out as we dissect it after the break.

Gallery: Samsung Galaxy Mega 6.3 review

Filed under: Cellphones, Tablets, Wireless, Mobile, Samsung, Google

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Source: http://feeds.engadget.com/~r/weblogsinc/engadget/~3/qupfIO-XfWo/

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Caterpillars attracted to plant SOS

July 1, 2013 ? Plants that emit an airborne distress signal in response to herbivory may actually attract more enemies, according to a new study published in the open-access journal Frontiers in Plant Science .

A team of researchers from Switzerland found that the odor released by maize plants under attack by insects attract not only parasitic wasps, which prey on herbivorous insects, but also caterpillars of the Egyptian cotton leafworm moth Spodoptera littoralis, a species that feeds on maize leaves.

When damaged, many plants release hydrocarbons called volatile organic compounds, similar to the compounds that cause the characteristic smell of freshly cut grass. These volatile organic compounds are known to be attractive to parasitoid wasps that lay their eggs inside other insects, killing them. Plants appear to use this strategy to fight back against herbivorous insects by calling for their enemies' enemies. In contrast, herbivorous insects tend to avoid the herbivore-induced volatile organic compounds.

"Adult moths and butterflies avoid food plants that are under attack by conspecifics. This seems adaptive, because it reduces both competition and the risk of predation by parasitoids. But we found that S. littoralis caterpillars are actually attracted to the odor of damaged maize plants, even when this odor is mimicked in the laboratory with a mix of synthetic compounds," said Prof. Ted Turlings, an author of the study and head of the Laboratory for Fundamental and Applied Research in Chemical Ecology Institute of Biology at the University of Neuch?tel, Switzerland.

To determine what kind of odors the caterpillars preferred, the researchers let the caterpillars chose among several odors by placing them in an olfactometer, a device consisting of four tubes connected to a central chamber, with each tube introducing an airflow carrying a different odor. The caterpillars were more than twice as likely to crawl towards the odor from maize plants under attack by conspecifics than towards undamaged plants, especially if the damage was recent and the caterpillars had already fed on maize.

So what might be the advantage to the caterpillars of moving towards plants that are already infested? "When S. littoralis caterpillars drop from a plant they are highly vulnerable to predators and pathogens in the soil, as well as to starvation. The advantage seems to be that fallen caterpillars can quickly rediscover the plant on which they fed. The caterpillars feed less and move more when exposed to high concentrations of the volatiles. By moving away from freshly damaged sites, they can minimize risk of predation and avoid competition," explained Prof. Turling.

Turlings and colleagues propose that hungry S. littoralis caterpillars do the best of a bad job by moving towards volatile organic compounds released by damaged maize plants. On these plants the competition may be more intense, but at least the caterpillars are assured of a suitable plant. Adult moths, on the other hand, are much more mobile and take little risk exploring the environment to discover the best food source -- so they avoid maize that is already under attack.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/705wA7hAnIw/130701135820.htm

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ICYMI podcasts: Photos for Pixels, death to Zigbee, and Google?s 3G balloons

It took months of waiting, but Chromebook Pixel owners received their promised new Photos app this week. On the GigaOM Chrome Show, Kevin Tofel and Chris Albrecht talk about what features it brings, while Chris debates which cloud he should use for photos and data. Meanwhile, Kevin is playing Gameboy games in the browser.

On this week?s Internet of Things podcast, Stacey Higginbotham chats with Qualcomm?s Rob Chandhok, who predicts the death of ZigBee and Z-Wave as connected home protocols. Instead, more open platforms and protocols will rise up and take precedence in this fast growing market of opportunity.

Summing up the news week, Jeff Roberts, Kevin Fitchard, Laura Hazard Owen chime in on the GigaOM Weekly WrapUp podcast. Topics include Pandora vs Pink Floyd, Google?s Project Loon (balloons as a network?!?) and getting pregnant in the digital age: Web searching your way through nine months.

(Download the GigaOM Chrome Show)

(Download the GigaOM Internet of Things podcast)

(Download the GigaOM Weekly Wrapup podcast)

Source: http://gigaom.com/2013/06/30/icymi-podcasts-photos-for-pixels-death-to-zigbee-and-googles-3g-balloons/

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Fake reviews of filibuster shoes are short on humor

The amazing viral rise of Wendy Davis from unknown Texas legislator to established national figure is complete: Her YouTubed 13-hour filibuster last Tuesday begat an Internet sensation; she was all over the Sunday yak shows this weekend; and this morning The New York Times has the obligatory How Technology Is Changing Public Discourse chin-stroking wrap-up.

But before we move on to whatever sensation the Internet will spit out this week, we need to address one troubling subplot here. I?ll leave it to others to determine what the Davis story means for politics; I am concerned about what it all means for goofing off on the Internet.

Like any Web-fueled phenomenon, the serious news of a politician laboring to thwart a piece of legislation she found troubling quickly spawned non-serious reactions. As is often the case, people latched onto an irrelevant detail as a potential source of lulz. This time it was Davis?s pink-and-green sneakers: The Amazon page for Mizuno Women's Wave Rider 16 Running Shoe quickly filled up with hundreds of fake ?reviews,? which various observers pronounced ?awesome,? ?passionate,? and ?trenchant.?

But when I actually read the reviews, I discovered something no one seemed to be mentioning: They are not funny.

Consider these alleged highlights: ?Guaranteed to outrun patriarchy.? ?I tried on a pair at the local mall and suddenly Texas Republicans started telling me what to do with my genitals.? ?If you are looking for a shoe that will never yield to the floor, pressure or good ol? fashioned boy?s club bullying this is the shoe for you.? ?Even if you wear these gems without sox for three days straight, they still smell better than a republican Lt. Governor who tries to push a low through past midnight.?

Whatever your politics may be, I seriously doubt you?re laughing at any of that. And my point here has nothing to do with politics, and everything to do with laughter. I?m a devoted fan of prank reviews on Amazon and other crowd-sourced mischief ? from the legendary Three Wolf Moon phenomenon to more recent instances involving a a strange banana slicer, the Bible, and many others. The best crowd-critique outbursts use comedy to transform the mundane ? even when there?s ideology involved, as in the Amazon review-bombing of Bic For Her pens. Something totally banal becomes a source of creative inspiration and genuine hilarity. Sublime.

The Davis shoe responses do something altogether different ? repurposing Amazon review space into just another medium for the same old party-line cheap shots. They are about as entertaining as status update along the lines of ?there goes [Fox/MSNBC] again, distorting the truth!? or the childish name-calling of any given comment thread.

Do we need more of that? We do not. That?s why I?m hoping these profoundly un-clever Davis shoe reviews are a one-off, not a harbinger. There?s plenty of room on the Internet for partisan bickering ? and even, I?ve heard, actual political debate. So please, keep the politics out of Amazon reviews, and store them where they belong: Internet comments sections, Twitter and your high school friend's Facebook page.

You can follow Rob Walker on Twitter; for all the latest tech news and opinion, you can also follow @YahooTech.

Source: http://news.yahoo.com/wendy-davis-amazon-reviews-not-funny-170335135.html

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Altitude sickness may hinder ethnic integration in the world's highest places

July 1, 2013 ? Ethnic segregation in nations straddling the world's steepest terrains may be reinforced by the biological tolerance different peoples have to altitude, according to one of the first studies to examine the effect of elevation on ethnic demographics.

Research from Princeton University published in the journal Applied Geography suggests that people native to low-lying areas can be naturally barred from regions such as the Tibetan Plateau, the Andes or the Himalayas by altitude sickness, which is caused by low oxygen concentration in the air and can be life-threatening. As a result, the homogeny of the local population can increase with elevation. In nations shared by people of high- and lowland extractions, this separation can potentially increase ethnic tension.

The researchers studied Tibet and found that elevation has heavily influenced the location of the surrounding region's population of Han Chinese, who make up 92 percent of China's population and originate from the country's eastern plains. Tibet has an average elevation of roughly 14,370 feet (4,380 meters) above sea level. The number of settlements with a large Han Chinese population peaks at around 8,900 feet (2,700 meters), while Tibetan settlements only begin to peter out beyond 17,000 feet (5,200 meters), the researchers found. The researchers attribute the sudden drop in the Han Chinese population to altitude sickness, and cite existing research showing that Han Chinese are indeed susceptible to altitude sickness in areas in which Tibetans thrive.

First author Christopher Paik, who undertook the study as a postdoctoral research scholar in the Empirical Studies of Conflict Project in Princeton's Woodrow Wilson School of Public and International Affairs, said that the research adds a new dimension to the study of how terrain influences demographic patterns. The field already explores the role of factors such as soil quality and access to the sea. The biological effects of elevation make altitude a particularly objective and reliable measurement for helping determine and understand how populations around the world's highest areas form, he said.

"There is very little research about the effect of altitude on migration patterns," said Paik, who is now an assistant professor of politics at New York University Abu Dhabi. "One of the nice things about using this geographical indicator as an independent variable is that there isn't any human intervention in determining the altitude of the region because it's established by nature.

"Rather than saying there is merely a correlation between settlement patterns and altitude, our research takes it one step further and suggests that altitude can directly determine the settlement patterns we see today. There's a causal story here," Paik said.

The separation that results from these settlement patterns could result in greater ethnic friction, Paik said. He initiated the current study in the wake of the 2008 unrest in Tibet, a series of protests that lead to imprisonment, detainment and clashes with Chinese security forces. Paik noticed that the most violent outbreaks occurred in areas of Tibet with the lowest relative concentrations of Han Chinese -- regions that also have the highest elevations. (Paik is currently working on a paper that correlates lower levels of violence during the 2008 unrest with lower elevation and greater Tibetan/Han integration.)

Paik and co-author Tsering Shawa, who heads the Digital Map and Geospatial Information Center in Princeton's Lewis Library, used 2000 Chinese census data to determine the Han population in settlements within the traditional Tibetan homeland, which includes the Tibetan Autonomous Region as well as portions of the Chinese provinces Qinghai, Gansu, Sichuan and Yunnan. They also gauged past Han Chinese presence through maps and a database developed by Shawa that indicate whether the official name of the 1,960 settlements in this area is Han Chinese, Tibetan or both.

The researchers found a similar distribution pattern of towns where at least one-third of the population are Han Chinese and traditional Han settlements (most of which date as far back as the 13th century) -- the bulk are located lower than 8,900 feet above sea level. No towns with a Chinese name exist above 15,000 feet (4,600 meters). Meanwhile, the greatest number of settlements with a Tibetan name stands at an only slightly lower elevation of 14,760 feet (4,500 meters), an area that the census shows has a minimum of Han Chinese inhabitants.

"What the outcome suggests is that there is a direct effect of altitude now as well as in historical settlement patterns," Paik said. "On the one hand there are settlements where Han Chinese came 1,000 years ago and established roots in that region, which makes it easier for migrants to come in. That provides a channel through which more Chinese live there today because their ancestors lived there as well.

"But if historical settlement is the only channel through which altitude influenced current settlement patterns, then there wouldn't be the direct influence of elevation through altitude sickness that we still see," Paik said. "Han Chinese still suffer from altitude sickness and the influence on settlement seems to persist today."

Paik and Shawa reference at least 10 studies that delve into the genetic adaption of Tibetans' blood cells and lung tissue to the low-oxygen conditions of a life on high -- a tolerance research suggests they share with Andes dwellers in countries such as Bolivia.

Han Chinese do not enjoy this predisposition even in modern times. The researchers cite a 2009 paper in the journal Clinica Chimica Acta that explored the genetic susceptibility of Han Chinese laborers to the pulmonary edema -- potentially fatal fluid buildup in the lungs -- they experienced during construction of the Qinghai-Tibet railway completed in 2005.

"The main contribution of this research is to point out geography does matter in ethnic demographic patterns," said Enze Han, an assistant professor of politics and international studies at the University of London. Han, who had no role in the research but is familiar with it, agrees with the researchers when they write that modern technology and transportation makes migration into high-altitude lands easier.

But, Paik said, the population distributions he and Shawa document show that geography -- via altitude sickness -- continues to play a strong role in regional diversity despite modern trappings such as the Qinghai-Tibet railway and government initiatives such as China's Western Development Program.

"Ethnic integration policy seems to work in the long run, but it will be harder to implement in the higher altitude regions," Paik said. "There seems to be a strong enough influence of altitude on settlement patterns such that even if you try to have integration happening there, nature works against those initiatives."

This work was supported by a grant from the Air Force Office of Scientific Research (AFOSR) award number FA9550-09-1-0314.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_environment/~3/9ZTFe8CoK9Q/130701151830.htm

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