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santosh maharshi writes “On social networks like Facebook, even if you have kept your profile very private, people can just look at your friends list and infer lots of vital information about you. Most of the social networks like Facebook and LinkedIn allow people to see your picture and your friends list as part of the open access for visitors (the article says that only 5% of Facebook users have bothered to hide their friends list). In a study titled You Are Who You Know: Inferring User Profiles in Online Social Networks (PDF), conducted by Alan Mislove of Northeastern University and his colleagues at the Max Planck Institute for Software Systems, an algorithm was tested that can accurately infer the personal attributes of Facebook users simply by looking at their friend lists. ‘At Rice [University], the algorithm accurately predicted the correct dormitory, graduation year, and area of study for the many of the students. In fact, among these undergraduates, researchers found that “with as little as 20 percent of the users providing attributes we can often infer the attributes for the remaining users with over 80 percent accuracy.”‘”

Source: On Social Networks, You Are Who You Know

An extensive study conducted on school children in Western Canada has proved that immunizing kids and adolescents goes a long way towards protecting the entire community from communicable diseases like the flu, thanks to a phenomenon known as “herd immunity.”

The findings come at a time when vaccine phobia is one of our largest public health concerns, with many parents worrying that immunizing kids can lead to adverse side affects. A recent survey revealed that one in four U.S. parents think that vaccines might cause autism, probably due in part to a 1998 paper published in the journal The Lancet that wrongly linked autism to vaccines–that paper has since been refuted, and fully retracted by the journal.

Now, scientists have more evidence that vaccines provide a public health benefit. Researchers studying youngsters in 49 remote Hutterite farming colonies in Canada found that giving flu shots to almost 80 percent of a community’s children created a herd immunity that helped protect unvaccinated older people from illness. As children often transfer viruses to each other first and then pass them along to grown-ups, the study provided solid proof that the best way to contain epidemics like the recent H1N1 outbreak is to first vaccinate all the kids. By immunizing the most germ-friendly part of the herd first, you indirectly protect the rest of the community, scientists say.

This is not the first time that scientists have found evidence that herd immunity can help protect the unvaccinated, but it’s the most definitive study on the subject yet. Researchers say this is the first such study to be conducted in such remote and isolated communities (the Hutterites‘ religious beliefs keep them separate from mainstream society), which reduced the chance that subjects could contract flu from other passing sources. Scientists say the new study provides “incontrovertible proof” that the shots themselves — rather than luck, viral mutations, hand-washing or any other factor — were the crucial protective element [The New York Times].

The study, published in The Journal of American Medical Association, focused on Hutterite farming colonies in Western Canada, where the people live in rural isolation in clusters of about 160 people. Though Hutterites drive cars and tractors, they shun radio and TV and each colony lives like a large joint family–eating together, going to a Hutterite school, and owning everything jointly.

In 25 of the colonies that joined the study, the scientists took school kids aged 3 to 15 years old and gave them flu shots in 2008. In 24 other colonies, the kids got placebo shots. In 2009, the researchers found that more than 10 percent of all the adults and children in colonies that received the placebo had had laboratory-confirmed seasonal flu. Less than 5 percent of those in the colonies that received flu shots had [The New York Times].

The study found that by vaccinating the kids against influenza, almost 60 percent of the larger community was granted “herd immunity” and protected against the illness. Carolyn Bridges, an expert in influenza epidemiology at the Centers for Disease Control and Prevention, says the study implies that giving flu shots only to schoolchildren would protect the elderly just as well as giving flu shots to the elderly themselves. The C.D.C. would never recommend that, she cautioned, “Because you still should vaccinate high-risk people” [New York Times].

The Hutterite study’s findings are in line with a previous study conducted in 1968, in Tecumseh, Michigan. In that study, flu expert Arnold Monto vaccinated almost 85 percent of the town’s schoolchildren during flu season. At the end of season, the town had only a third as many flu cases as nearby Adrian, Mich., which received no shots. There were far fewer cases of flu in all age groups [New York Times].

Image: iStockPhoto

Source: Vaccinating School Kids Can Protect the Whole “Herd” of Community Members

The theory of general relativity: It works. OK, it’s not exactly Earth-shattering news that Albert Einstein’s century-old idea works in real life. That’s been shown over and over. But what had been difficult for researchers to do until now was verify the theory on truly massive scales beyond the solar system, that of whole galaxies and clusters of galaxies. This week in Nature, Reinabelle Reyes and colleagues report that they did it, and that Einstein was proven correct once more.

While the find is a nice coup for Reyes’ team, its importance goes beyond just reaffirming the great scientists of yesteryear with yet another “Einstein was right” story. The existence of dark matter and dark energy is based on the assumption that Einstein’s gravity is affecting galaxies billions of light-years from Earth in the same way that it affects objects in our solar system [National Geographic]. However, if the study had shown that general relativity needed a slight adjustment at vast distances (like the nudge Einstein himself provided to Newton’s physics), that could have altered prevailing ideas about dark matter and energy. This research indicates those pesky ideas may be here to stay [Space.com].

Reyes’ approach combined the study of galaxies’ gravitational lensing (how much they bend the light from surrounding galaxies), their velocities, and how and where they formed clusters. All of these measurements combined created a system to test theories of gravity independent of particular parameters in the theories [Space.com]. What they found closely matched what you’d predict under general relativity. They tested two alternative gravitational theories, too. One, called tensor-vector-scalar (TeVeS), gave results beyond the study’s margin of error. Another, called f(R), didn’t work as well as general relativity. But it fell within the margin of error, so the scientists say it will take more research to disprove it.

Meanwhile, as the spirit of general relativity is reaffirmed in the pages of Nature, the pages upon which Einstein formulated the theory are going on display in Jerusalem. Elsa, his wife, gave the pages to Hebrew University, and they are currently part of 50th anniversary festivities at the Israel Academy of Sciences and Humanities. Each of the 46 pages, labored over between November 1915 and their publication in May 1916, has its own case, each lighted dimly in a room that has been darkened to protect the paper. There on Page 1 is the now familiar title in German: “The Foundation of the General Theory of Relativity” [The New York Times].

However, if you need more Einstein and can’t make the trip to Israel, check out his mustachioed mug on the cover of the April DISCOVER issue, on newsstands this week.

Image: Ferdinand Schmutzer

Source: Einstein Proven Right (Again!) by the Movements of Galaxies

Xemu writes “Computer’s don’t make children fat, but watching TV for the same length of time does. This is shown by a recent Swedish study of all school children in Lund’s county conducted by RN Pernilla Garmy. The results were clear: The child’s obesity was directly affected by placing a TV in the child’s room, but placing a computer in the room had no effect at all. One theory is that it’s common to have a snack in front of the TV, while a computer requires a more active user, for example when chatting or playing games.”

Source: Study Shows TV Makes Kids Fat, Computers Don’t

Contagiousness: It’s contagious! Happiness was contagious in 2008, then loneliness last year, and don’t forget being fat. Now it’s generosity that spreads like the flu across social networks, according to James Fowler and Nicholas Christakis (who were both behind the happiness study). Their new study appears in the Proceedings of the National Academy of Sciences.

To test out whether generosity spreads, the scientists devised a game. In groups of four, each person had 20 “credits,” some of which they could decide to toss into a common fund for all the players. The scoring was set up so that giving to the fund was costly unless the other players did it too: If everyone kept their money, they’d have the 20 credits, but if everyone put all they could into the fund, each player would end up with 32. However, the players had no way to know how generous the others were being. The best payoff would come if everyone gave all their money — but without knowing what others were doing, it always made sense to keep one’s money and skim from the generosity of others [Wired.com].

The researchers found that if a person was particularly generous, the people he or she played with were more likely to be generous during the next round, when they were shuffled into groups with different people. Ultimately, the initial person’s contribution was multiplied up to three times—a result in keeping with earlier findings on social contagion suggesting that this sort of ripple effect continues for three degrees of separation [TIME]. However, while kindness and generosity spread through the network of players, selfishness did too.

Certainly, these studies have their doubters. Commenters on one of our last “contagious” posts pointed to a 2008 BMJ study noting that if social networking studies weren’t careful in looking at correlations, one could plausibly find that traits like height, acne, and headaches are similarly contagious. Though Fowler and Christakis designed their experiment to try to see cause-and-effect links, not just correlation, they say the study is a general model for group behavior, and how well it fits the more convoluted real world remains to be seen.

But we talking apes are impressionable social creatures, after all, so perhaps we really do spread behaviors—and not just disgusting infectious diseases—amongst ourselves. Says Fowler, “When people benefit from kindness they ‘pay it forward’ by helping others who were not originally involved, and this creates a cascade of co-operation that influences dozens more in a social network” [The Telegraph].

Image: flickr / Woodleywonderworks

Source: Generosity Is Contagious, Study Shows–But Selfishness Is Too

College students holed up in the library or cramming for an exam have always relied on stimulants like coffee, but recently they’ve been increasingly turning to the off-label use of drugs like Ritalin and Modafinil to help them stay focused. Now scientists have found how Ritalin, a drug normally prescribed for children with attention deficit hyperactivity disorder (ADHD), helps boost learning.

In a new study of rats published online in Nature Neuroscience, scientists found that Ritalin appears to boost both attention and enhance the speed of learning by increasing the activity of the chemical messenger dopamine [Technology Review]. The study also found that one type of dopamine receptor aids the ability to focus, and another type improves the learning itself [DNA].

In their study, scientists observed that rats on Ritalin learned faster than those not given the drug; the Ritalin-drugged rats understood more quickly that a flash of light and sound meant sugary treats for them. However, when the researchers used drugs to block the dopamine D1 receptors in the rats’ brains, they found Ritalin did not aid learning speed. When another dopamine receptor, D2, was blocked, the drug failed to improve focus. The scientists concluded that both receptors play a distinct role in helping Ritalin improve cognitive performance. Said lead researcher Antonello Bonci: “Since we now know that Ritalin improves behavior through two specific types of neurotransmitter receptors, the finding could help in the development of better targeted drugs, with fewer side effects, to increase focus and learning” [Technology Review].

The researchers also observed that the drug strengthened the connections between nerve cells in the brain region called the amygdala, which plays an important role in learning and emotional memory. Strengthened connections increase the efficiency of neural transmissions, which allows for faster learning.

The findings come at a time when doctors are paying more attention to the trend of using pharmaceuticals as “smart pills.” Some doctors have warned that drugs like Ritalin and Modafinil shouldn’t be abused to get a “brain boost” ahead of exams or in stressful situations, while other scientists have provocatively suggested that such medications should be available to anyone who wants a cognitive pick-me-up.

Image: iStockphoto

Source: How Ritalin Works in the Brain: With a One-Two Dopamine Punch

You are what you eat, and perhaps in some ways, what your mother ate. Back in 2003, Cheryl Rosenfeld’s team found that the diet they fed to pregnant mice caused a “striking variation” in the sex ratios of the offspring: High fat favored males, low fat favored females. Now Rosenfeld has a new study in the Proceedings of the National Academy of Sciences that says the mother’s diet can also affect the very way genes are expressed in the placenta.

To figure this out, Rosenfeld’s team studied the placentas attached to fetal mice 12 and a half days after conception, when the mice were midway through gestation but had yet to produce sex hormones like estrogen or testosterone (those can also alter gene expression, which would have confounded the study). They found that gene activity in the placentas differed significantly depending on whether the mom was fed a high- or low-fat diet. The biggest differences were found when comparing the high- and low-fat placentas linked to female fetal mice, suggesting that placentas nourishing females do a better job of responding to diet—and potentially protecting the fetus from harmful ingredients—than do those connected to males [ScienceNOW]. Specifically, of the 700 genes that they saw behave differently between the sexes, 651 were expressed more in females than males. In all, their study saw changes in the expression of nearly 2,000 genes.

The team can’t say for sure why diet affects either sex ratio or gene expression. Indeed, the analysis turned up changes in genes that affect things like kidney function and smell, which the scientists were not expecting to see. Whatever the reason these changes happen, they say, diet during pregnancy could have long-term health effects on children. Sons and daughters are also at different risk for conditions such as obesity or diabetes later in life, apparently related to either the mother’s diet or body condition while pregnant [The Times].

Biologist Jared Friedman, who didn’t work on the current study, says this will be an interesting area for future studies, but he’s not totally sold on the conclusion of Rosenfeld’s team yet. Males, he says, seem to lag behind females in all stages of development. Maybe those olfactory genes become more active in the male placenta as the pregnancy continues, he says. “Instead of 12.5 days, go to 19.5 and see if the differences are magnified or if the males catch up” [ScienceNOW].

Image: flickr / dizznbonn

Source: Can Mom’s Diet Shape Baby’s Genes? Study of Pregnant Mice Suggests So

When researchers rack up the carbon emitted across the world, the standard trends emerge: Europeans put less CO2 into the atmosphere than Americans, but China’s rapid ascent is sending its emissions shooting past those of the United States. However, this week in the Proceedings of the National Academy of Sciences, Stanford University researchers attempt to rejigger the numbers to reflect not just where the emissions are produced, but who is responsible for them—who’s buying and consuming the products that cause those emissions.

After study global trade databases, Steven Davis and Ken Caldiera say that in 2004, 23 per cent of global CO2 emissions – some 6.2 gigatonnes – went in making products that were traded internationally. Most of these products were exported from China and other relatively poor countries to consumers in richer countries [New Scientist]. The researchers say that developed countries outsource about a third of the carbon dioxide emissions connected to their consumption.

When you look at the numbers this way, the per capita emissions in Europe don’t look quite as good: If those emissions were tallied on the other side of the balance sheet, it would add more than four tons of CO2 per person in several European nations [TIME]. The United States saw a lesser increase of 2.4 tons per person, though that’s not really a cause for celebration. Part of the reason is that the country has more carbon-intensive exports than Europe, the study says, and under the new accounting those emissions are going on somebody else’s books. The United States also takes in the lion’s share of China’s: 22.5% of China’s emissions are generated during production of goods and services consumed overseas, and 7.8% are embodied in exports to the US alone [BBC News].

This isn’t the first time that climate change experts have raised the question of how much responsibility consumers bear for carbon emissions produced on the other side of the globe. Other studies are trying to crack this same problem, tracking “consumption” emissions rather than just the “territorial” emissions produced inside a country’s borders. What they find could shake up how the world goes about trying to reduce emissions. The U.N. system is built around the idea of capping carbon emissions from individual nations. But which country is responsible for the carbon emitted in global trade? The buyer or the seller? [TIME]

Image: iStockphoto

Source: When China Makes Goods for the US, Who’s Responsible for the Emissions?

Behind the ongoing back-and-forth fights over climate change that usually focus on carbon, there has lingered the threat of the powerful greenhouse gas methane being released into the atmosphere and causing even worse trouble. In August we reported on a study that noted methane bubbling up from the seafloor near islands north of Norway, giving scientists a scare. This week in Science, another team reports seeing the same thing during thousands of observations of the East Siberian Arctic Shelf on Russia’s north coast, which is even more worrisome because it’s a huge methane deposit.

The shelf, which covers about 800,00 square miles, was exposed during the last ice age. When the region was above sea level, tundra vegetation pulled carbon dioxide from the air as plants grew. That organic material, much of which didn’t decompose in the frigid Arctic, accumulated in the soil and is the source of modern methane [Science News]. Now underwater, it’s covered by a layer of permafrost. But that permafrost seems to be becoming unstable, thanks to the fact that the water on top of it is warmer than the air it was exposed to back when it was on dry land.

The study said about 8 million tonnes of methane a year, equivalent to the annual total previously estimated from all of the world’s oceans, were seeping from vast stores long trapped under permafrost [Reuters]. Study leader Natalia Shakhova says methane levels in the Arctic haven’t been this high in 400,000 years. While we’re not about to teeter off a cliff—that 8 million tons is a small portion of the global emissions of 440 million tons—we should be concerned, the scientists say. Methane is a far more powerful greenhouse gas than carbon dioxide, absorbing at least 25 times more heat, NOAA says.

It is possible that climate change could be contributing to the release, with warmer seas causing more methane to come out, creating a feedback loop. But methane has long been leaking, and there’s no record of the previous levels with which to verify how much methane emissions are increasing, or whether people are playing a part. While Shakhova says the warmer runoff into the Arctic ocean is probably contributing, the team can’t say that for sure.

What they can say for sure is that the methane levels there are extremely high. Most undersea methane oxidizes into CO2 as it enters the atmosphere, but Shakhova says the East Siberian Ice Shelf methane is too close to the surface for that to happen. As a result, she said, atmospheric levels of methane over the Arctic are 1.85 parts per million, almost three times as high as the global average of 0.6 or 0.7 parts per million. Concentrations over the shelf are 2 parts per million or higher [The New York Times].

Image: University of Alaska Fairbanks

Source: Globe-Warning Methane Is Gushing From a Russian Ice Shelf

The human genome may have been sequenced back in 2004, but that was a far cry from documenting all the genes inside us. Our bodies are home to a dizzying number and variety of bacteria, and in a study published in this week’s Nature, researchers have used metagenomic sequencing to catalog the genes that belong to the microbes living in our guts.

The project, which sampled 124 European people, found that each individual had at least 160 species of bacteria living in his or her digestive tract, and there’s a lot of overlap between our guts. At least 57 species of bacteria were present in just about everybody. Overall, the researchers cataloged about 1,000 different bacteria species and figure there’s another 150 or so they haven’t found [AP].

Researcher Jeroen Raes reminds us that no matter if we’re grossed out by the fact that bacteria infest our body, we depend on them. “The bacteria help digest food, provide vitamins, protect us from invading pathogens. If there’s a disturbance, people get all sorts of diseases such as Crohn’s disease, Ulcerative colitis, and a link has also been made to obesity” [BBC News]. In addition, he says, we have 10 times the number of bacterial cells in our bodies than human cells, and 100 times bacterial genes than our own. So we’re pretty much walking bacteria farms.

It’ll take time to sort out the tangled web of data from all those microbial species. Study coauthor Wang Jun says one of the ultimate goals is to pin down relationships between bacteria and diseases like those that Raes listed. “If you just tackle these bacteria, it is easier than treating the human body itself. If you find that a certain bug is responsible for a certain disease and you kill it, then you kill the disease,” Wang said [Reuters]. Wang is currently working on a similar study in China.

In the meantime, some, like outside researcher Elaine Holmes, were just impressed that this feat could be achieved. “It uses a large number of participants and therefore one assumes it is more representative of the ‘real’ microbial composition than previous studies. Also, it is an amazing feat of data processing” [BBC News].

Image: iStockphoto

Source: Scientists Sequence DNA From the Teeming Bacterial Universe in Your Guts