Smart. Sharp. Funny. Fearless.

Monday, December 09, 2019 {{ new Date().getDay() }}

Study: Weekend-Only Drug Use Frequently Slips Into Weekday Drug Use

By Deborah Netburn, Los Angeles Times (TNS)

Beware, weekend ragers: A new study suggests that people who use drugs only on the weekends frequently begin using them on weekdays too.

In a paper published Monday in Annals of Family Medicine, researchers report that 54 percent of people who said they restricted their drug use to Friday night, Saturday or Sunday admitted to using drugs on other days of the week as well, when questioned again in six months.

“The study shows us that patterns change,” said lead author Judith Bernstein, a professor of community health sciences at Boston University School of Public Health. “Only 19 percent of people who originally said ‘I use on weekends’ still used only on weekends.”

Not all the weekend-only drug users went to more frequent drug use over the six-month period, however. According to the paper, 26.9 percent of the original weekend-only drug users said they were abstaining from drugs entirely when asked about their drug use half a year later.

The new study is based on data collected from 483 primary care patients at Boston Medical Center who admitted during a primary care visit to using drugs in the past month. The patients were mostly male and African-American, and the authors describe them as “typical of an inner-city population with recent drug use.” It should be noted, however, they were showing up for regular care, not drug care.

Of the 483 participants in the study, 431 (89 percent) said they used drugs on weekdays and weekends, while just 52 (11 percent) said they used drugs on weekends only.

When the patients were questioned again about their drug use six months later, both groups reported a similar amount of increase in drug use and more than half of the weekend-only group were now using drugs on the weekdays too, Bernstein said.

According to the authors, their research suggests that primary care physicians should follow up on patients’ self-reported drug use even if it seems simply “recreational.”

“When I was working in clinical care I would have patients say, ‘I just use drugs on the weekend’ or ‘I’m just a recreational user’ as if that doesn’t matter so much,” said Bernstein. “I think clinicians need to understand a little more than perhaps they do now how these patterns change over time.”

She added that today, when a patient tells a doctor that he or she is using drugs on the weekend, the doctor usually does not note it as a problem, and is unlikely to ask about changes in drug use in subsequent visits.

Bernstein would like to see that change, especially because changes in drug use can interfere with the effectiveness of medications for blood pressure or diabetes.

“The real message of this paper is a monitoring message,” she said. “Drug use is not static, so drug use is something you might want to monitor on a regular basis.”

(c)2015 Los Angeles Times, Distributed by Tribune Content Agency, LLC.

Photo: Tanjila Ahmed via Flickr

Stable Philae Lander Sends Back First Images From Surface Of Comet

By Deborah Netburn, Los Angeles Times (MCT)

The Philae probe is alive and well a day after the first successful spacecraft landing on a comet, but scientists are still trying to figure out exactly where it is on its new home.

Officials at the European Space Agency mission control in Darmstadt, Germany, confirmed Thursday that the lander, launched from the Rosetta spacecraft circling comet 67P/Guryomov Geraskimenko, is busily sending back data from the surface — including the first images ever taken from the surface of a comet.

While it was touching down, the lander bounced twice — almost as if the comet were a trampoline. The first bounce was major. It lasted almost two hours and took the lander about two-thirds of a mile above the comet’s surface. The second bounce was smaller and lasted just a few minutes, said Stephan Ulamec, the Philae landing manager. The craft’s harpoons failed to attach it to the surface after touchdown Wednesday but it’s now stable, scientists said.

The lander then settled in a shadowy part of the comet near a cliff, where it is only getting 1 hour of sunlight a day. At its planned landing site, Philae would have gotten six or seven hours of sunlight. The difference is crucial because Philae will need to rely on solar power after its batteries run out, and this will affect how much work the probe can do on the surface, mission officials said.

Scientists also said Philae landed with two legs on the ground and one foot in the air during its final touchdown. Ulamec said the lander has the capability to make a little “hop” on the surface, which could help it get into a better position, but the maneuver would be risky and it is not likely ESA will try it.

And because Philae’s harpoons failed to keep it tethered to the comet, ESA officials are also wary of drilling into the comet as planned. Their concern is that the force of the drills on such a low gravity body could cause the lander to move again.

The ESA team conceived the risky Rosetta mission in the late 1980s to learn more about comets that formed from the same mix of gas, dust and other ingredients that would form the sun, Earth and other planets. Spacecrafts have slammed into comets before, but none had ever landed intact before Wednesday.

Photo: European robot probe Philae has made the first, historic landing on a comet after descending from its mothership on Tuesday, Nov. 12, 2014. It was designed to shine a light on some of the mysteries of these icy relics from the formation of the Solar System. The landing caps a 6.4 billion-kilometer journey that began a decade ago. (ESA/Rosetta/Zuma Press/MCT)

Study: 5 Days Away From Computer Screens Boosts Preteens’ Social Awareness

By Deborah Netburn, Los Angeles Times

What happens when you take about 50 sixth-graders and send them to a nature camp with no access to computers, tablets, and mobile phones? A new study suggests that after just five days their ability to understand nonverbal social cues improves.

Nonverbal social cues are the emotional information we pick up from people around us that is not communicated through words. It includes facial expressions, eye contact, tone of voice, and body posture.

As children spend more time corresponding with their friends via text rather than talking to them face to face, the researchers wondered whether they were losing the ability to read these important cues.

“The idea for this study came from looking at the way my older child and her friends’ older siblings were communicating,” said Yalda Uhls, who runs the Los Angeles office of the nonprofit Common Sense Media. “I’ve been at parties where the kids are all hanging out, but instead of looking at each other, they are staring at their phones.”

Uhls, who is the lead author of the study published in the journal Computers in Human Behavior, wanted to see what would happen if a group of children had to spend an extended period of time communicating completely device-free.

Uhls and senior author Patricia Greenfield of the University of California, Los Angeles found a public school that sends its sixth-grade class to a wilderness camp near Big Bear, Calif., for five days. At the camp, the students have no access to electronics.

When the class of about 50 children arrived at the camp, they were asked to take two tests to measure their ability to read nonverbal social cues. In the first, the kids were asked to assess the emotions portrayed in 48 photos of people making faces. In the second test, they watched a video with the sound turned off, and then made a judgment about the emotional state of the actor.

At the end of the five-day camp, the students were asked to take the tests again. The researchers report that over the five days the kids went from making an average of 14.02 errors on the face-recognition test at the beginning of their camp stay to 9.41 errors by the end. For the video component, they went from getting an average of 26 percent of the emotional states correct to getting 31 percent correct.

“Honestly, we were pretty surprised that just five days would have that affect,” said Uhls. “But we think this is good news because if indeed lack of face-to-face time is changing people’s ability to understand emotion, our results suggest you can disconnect for five days and get better.”

The researchers gave the same test to a control group of 54 sixth-graders from the same school who had not yet attended the camp. That group had an average of 12.24 mistakes the first time they took the face-recognition test and 9.81 mistakes when they took it again five days later. For the video test, the students’ scores stayed flat, getting an average of 28 percent of the emotions correct both times they were tested.

Though the children who were at the camp showed a larger improvement over the five days than those who did not go to camp, the end results were not that different.

“I noticed that too,” said Uhls, “but even though the kids ended up in the same place, they started at different places, so the change is what we are really looking at.”

Uhls and Greenfield said the results of their study suggest that it is important for kids to spend time away from screens, but it doesn’t necessarily suggest that all screen time is bad.

“The main thing I hope people take away from this is that it is really important for children to have time for face-to-face socializing,” said Uhls. “I love media, my kids are media-savvy, but it is really important to have a balance.”

AFP Photo/Frederic J. Brown

Interested in health news? Sign up for our daily email newsletter!

Study Finds No Link Between Certain Weather Conditions, Lower Back Pain

By Deborah Netburn, Los Angeles Times

Have you ever noticed that your lower back pain flares up during a rainstorm? Or when the temperature suddenly drops? Or when there’s a change in humidity or air pressure?
Well, then you’ve been noticing wrong, according to a study published this week in the journal Arthritis Care & Research.

In a paper titled, “Weather Does Not Affect Back Pain,” researchers from the Sydney Medical School at the University of Sydney in Australia found no connection between changes in temperature, relative humidity, air pressure, wind direction or precipitation, and an increase in lower back pain episodes.

Oddly, however, the researchers found that higher wind speeds and wind gust speed were associated with a small increase in back pain. The correlation reached statistical significance, but the authors say that the magnitude of the increase was not clinically important, and they do not go on to explain what may be responsible for the finding.

Data for the study were collected in Sydney from October 2011 to November 2012. The researchers gathered information from 993 people who showed up at their primary care doctor’s office hoping to get treatment for a sudden onset of intense lower back pain.

To be included in the study, the patients had to have gone to see their doctor specifically because of pain between their 12th rib and the “buttock crease.” The pain had to have developed over a period of no more than 24 hours, and none of the patients could have known or suspected serious spinal problems. All patients in the study were 18 years or older.

Participants were asked to give specific information about where they lived and the exact time that their lower back pain started to increase. The researchers cross-referenced that information with meteorological data from the Australian Bureau of Meteorology, which has five weather monitoring stations in Sydney.

The patients did not know that the study had anything to do with weather and lower back pain, nor did the interviewers. At the time they were collecting information from the participants, they were working on a different study that looked at physical and psychological triggers for lower back pain. It is only after they published that research that they decided to see whether there were any links between the back pain data they had collected and historical weather information.

Though they ultimately found no relationship between weather and lower back pain, the researchers are not ruling out that weather can affect pain at all. For example, they note that a previous study found higher temperatures and lower pressures can lead to an increase in headaches.

“Our findings refute previously-held beliefs that certain common weather conditions increase risk of lower back pain,” said Daniel Steffens of the George Institute for Global Health at the University of Sydney, who was the lead author on the study. “Further investigation of the influence of weather parameters on symptoms associated with specific diseases such as fibromyalgia, rheumatoid arthritis, and osteoarthritis are needed.”

AFP Photo/Don Emmert

Interested in health news? Sign up for our daily email newsletter!

Study: Not Enough Exercise Is Likely To Blame For Obesity Epidemic

By Deborah Netburn, Los Angeles Times

LOS ANGELES — A new study suggests that under-exercising, rather than overeating, may be at the heart of America’s obesity epidemic.

Researchers from Stanford University School of Medicine report a strong correlation between the rise in obesity and a striking drop in the amount of time Americans spend exercising when not at work over the last 22 years.

Their analysis uncovered no evidence that American’s have increased their daily calorie count in the same time period.

“We wouldn’t say that calories don’t count, but the main takeaway is that we have to look very carefully at physical activity. The problem is not all in the intake of calories,” said Dr. Uri Ladabaum, a professor of gastroenterology at Stanford Medical School. Ladabaum is also the lead author of the study that will be published in the August issue of the American Journal of Medicine.

The study relies on data collected by the National Health and Nutrition Examination Survey from 1988 to 2010, which Ladabaum and his team used to look for trends in obesity, abdominal obesity, physical activity, and caloric intake in the last two decades.

The most startling finding in the study is the drop in the amount of exercise Americans do in our free time. The researchers found that from 1988 to 2010, the percentage of adults who reported doing no exercise in their free time grew dramatically from 19 percent to 52 percent in women, and from 11 percent to 43 percent in men.

“We suspected there was a trend in that direction, but not that magnitude,” said Ladabaum. “People can get exercise in other ways, but most people don’t walk or bike to work, and most people are not in jobs that require physical activity.”

At the same time, the researchers found that the prevalence of obesity increased from 25 percent to 35 percent in women, and from 20 percent to 35 percent in men. In that time period the proportion of normal weight men and women dropped, while the proportion of overweight men and women remained the same.

But here comes the surprising part: The researchers did not find any evidence that people were ingesting more calories on a daily basis in 2010 than they were in 1988.

“The one caveat here is that the amount of calorie intake was based on self-report, so it is possible people were not recalling correctly what they ate, or not reporting correctly,” Ladabaum said.

Ladabaum notes that the study can tell us only that a major drop in time spent exercising occurred at the same time as a rise in obesity, not that one caused the other.

“The study looks at trends and certain associations, but does not prove any cause and effect between these,” he said.

He also wants to make clear that the fact that the average caloric intake did not change substantially does not mean that caloric intake has been optimal at the population level or at the level of individuals.

“We simply did not detect a substantial increase over time,” he said.

Photo via WikiCommons

Interested in health news? Sign up for our daily email newsletter!

Scientists Come Up With Pass Codes You Can’t Forget

By Deborah Netburn, Los Angeles Times

Imagine a whole new type of password — one that lets you dispense with all those numbers, letters and symbols, but is still impenetrable to attackers.

Researchers at Britain’s University of York and the University of Glasgow have created a new password system that could one day allow users to access their bank accounts, their phones or their favorite websites simply by picking out a familiar face from a grid of nine faces, four times in a row.

They call the system Facelock, and according to a new study published in the journal Peer J, it is teeming with benefits. Most impressively, users were able to log into a test system using Facelock after not using it for an entire year.

Facelock is not the first password system to experiment with graphical elements. A system called Passfaces requires a user to pick out a photo of someone they know from a grid of faces. But Facelock has an important difference. The images in the Facelock system are always changing — even the image of the familiar face.

The research team explains that people do not recognize all faces equally. We have no trouble identifying a familiar face across a series of different images that range in quality. On the other hand, when a face is not familiar to us, we are likely to think that different images of the same person are actually images of different people.

This well-studied psychological phenomenon can be frustrating to police when they ask a witness to identify a person caught in a fuzzy security camera tape, but in the case of Facelock, the researchers were able to exploit it for the good of frustrated password users. They proposed that even a nefarious “shoulder surfer,” who was spying over a user’s shoulder when that user selected a familiar face, would have trouble picking out the same person in a different image.

To test this hypothesis, they asked 120 volunteers to come up with between four and 10 different people whose faces would be familiar to them, but not to most people. Specifically, the researchers asked participants to come up with a “Z-list celebrity” — someone for whom there would definitely be pictures on Google Images, but who was only known to a narrow group of people. Perhaps a famous skier, or a well-regarded cello player.

After the Z-list celebrity had been selected, the volunteers were asked to log into a website using the Facelock system. The idea was that one face in each of four grids would be familiar to the volunteer, but none of the faces would be familiar to an attacker. One week after having selected their familiar faces, 97.5 percent of participants had no problem logging on. One year later, 86.1 percent of participants were still able to choose their Z-list celebrity’s face, no problem.

“I didn’t think I could log in because I couldn’t remember any of the people I chose — but I did!” wrote one participant who is quoted in the study.

Another said: “I got them all right. Did you use the same images of the people or different ones? I got the impression I did not recognize the image but the person.”

The researchers also looked at how vulnerable the Facelock system is to attack by strangers, as well as people who are close to the users, such as a spouse or other family member, and those “shoulder surfers” mentioned above.

Facelock was found to be essentially impermeable to people who don’t know the users. Even people who were very close to the users were only able to get through all four grids successfully 6.6 percent of the time.

“Taken together the success rates of account holders (97.5 percent), random zero-acquaintance attackers (<1 percent), and nominated high-acquaintance attackers (6.6 percent) strike us as a promising starting point,” the researchers write in the paper.

To test how permeable the system was to shoulder surfers, the researchers gathered 32 undergraduate students in a room and used a projector to show them an authentication code. (A green box highlighted the familiar faces chosen by one of the original volunteers in the grid.)

Then, the students were asked to pick out those same faces from another grid that had different images of the same person. Even in these beyond-ideal shoulder-lurking circumstances, the graduate students were successful only 1.9 percent of the time.

It may sound good, but you shouldn’t expect to see Facelock coming on the market anytime soon. The researchers say the aim of their work is not to create a new password system, but rather to “raise awareness of the important psychological contrast between familiar and unfamiliar face processing, and to explore the potential for exploiting this contrast in the context of authentication,” they write.

Still, those of us who loathe the direction pass codes have gone — more numbers, more symbols, longer — can dream of a day when all it requires to check your banking statements is to pick out an image of your favorite Z-list celebrity.

Ron Bennetts via Flickr

Lab Mice Get Addicted To Sun Exposure

By Deborah Netburn, Los Angeles Times

LOS ANGELES — Does basking in the sun make you feel relaxed and happy, like nothing can bother you? There may be a biological reason for that.

Researchers found that mice who were regularly exposed to UV light had a higher pain tolerance than mice that were not exposed to UV light. They also experienced withdrawal symptoms when the UV light was taken away.

In other words, the mice’s response to the UV radiation was similar to what would happen if the scientists had given them low doses of heroin.

“I know people are thinking, heroin and UV radiation, give me a break,” said David Fisher, professor of dermatology at Harvard Medical School and Massachusetts General Hospital, who led the study. “But we think there could be evolutionary reasons for it.”

Previous studies had already established that people who obsessively frequent tanning salons can exhibit addictive behaviors, but nobody knew exactly what was triggering that response.

“What our study added is the mechanism,” Fisher said. “How does it happen.”

Fisher and his team started their series of experiments by shaving the backs of mice and exposing them to UV radiation five days a week for six weeks. Each exposure was designed to be similar to what fair-skinned people in Florida would experience if they spent 20 to 30 minutes in mid-day summer sun.

Within the first week, the researchers found that the UV-exposed mice had elevated levels of beta-endorphins — a naturally occurring opioid — circulating throughout their bodies.

This wasn’t a huge surprise for the scientists. They already knew that beta-endorphins were produced in the skin in response to UV radiation. What they didn’t know was whether it was possible for beta-endorphins produced in the skin to affect the mice’s behavior.

To find out, they put the mice through a series of tests. They discovered that mice that had been exposed to UV radiation were less sensitive to heat and pain than their non-UV exposed counterparts. When they treated the UV-exposed mice with naloxone, a drug that inhibits opioids in the body, the same mice responded totally normally to these tests of pain.

The researchers also found that the UV-exposed mice became addicted to the elevated levels of beta-endorphins. Mice that received naloxone after days of UV exposure showed classic signs of opioid withdrawal like paw tremor, teeth chatter, and wet dog shake.

Fisher said there are two reasons it made sense to do this study on mice. “It happens that the response of skin to UV radiation is remarkably similar in mice and humans,” he said. “Mice tan, and the same gene regulates pigment in mice and in people.”

He added that using a mouse model also allowed the team to ask very specific questions about the mechanisms that make sun exposure addictive. For example, they ran the same tests described above on mice that were missing the beta-endorphin gene. These mice did not exhibit any change in their pain threshold when they were exposed to UV light, nor did they show any withdrawal symptoms when given naloxone.

“That is enormous,” Fisher said. “Now we know that UV light and increased beta-endorphins don’t just correlate, but that the endorphin is mediating behavior.”

The researchers hypothesize that this feel-good feeling we get from the sun may have once been physically beneficial for humans who were perhaps not getting enough vitamin D.

Fisher said he hopes that the study, published in the journal Cell, will help people better understand why sunbathing continues to be so seductive, in spite of all the ways we now know it harms our skin.

“There is real damage that comes from frequent UV exposure,” said Fisher. “If people recognize that their behavior of going out and tanning may go beyond a conscious decision, maybe they will be better able to avoid it.”

Asteroid Impact That Killed The Dinosaurs Also Cooled The Earth

By Deborah Netburn, Los Angeles Times

LOS ANGELES — The asteroid that wiped out the dinosaurs also caused a temporary but devastating “impact winter” — darkening the sky, cooling the Earth and inhibiting photosynthesis, new research suggests.

Sixty-six million years ago, a 6.2-mile-wide asteroid known as Chicxulub struck the Earth off the Yucatan coast, setting off a series of catastrophic events that led to one of the world’s worst mass extinctions.

Computer simulations suggest that in the hours immediately after the impact, life on Earth was rattled by massive earthquakes and tsunamis, as well as global wildfires.

Then, dust and soot rose into the atmosphere, absorbing sunlight and keeping it from reaching the Earth’s surface. Plants had trouble getting enough light to photosynthesize, causing a wide-scale collapse of the food web. At the same time, the surface of the planet began to cool.

Because water holds onto heat longer than land or air, there were initially significant temperature differences between the atmosphere and the oceans that led to large storms and hurricanes.

The impact winter did not last long, however. Over a few months or possibly a few decades, the dust and soot fell out of the atmosphere and rained down onto the land and oceans, allowing sunlight to warm the planet once again.

It’s a compelling story, but one that has been difficult to prove — until now. Writing in the Proceedings of the National Academy of Sciences, a team of scientists from the Netherlands say they have found the first hard evidence of the hypothesized impact winter, buried deep in the geological record.

To take the temperature of the Earth 66 million years ago, the researchers looked at lipids produced by an ocean-dwelling microorganism called Thaumarchaeota, preserved in sediment rocks near the Brazos River in Texas.

Thaumarchaeota adjust the composition of the lipids in their cell membranes to the temperature of the sea water. When the organism dies, it sinks to the sea floor, and the lipids in its membrane are preserved in sandy ocean sediments.

Because the impact winter didn’t last long, it was difficult for the researchers to find a place where there was a thick enough sediment layer to look for the tell-tale lipid composition that would imply a short but severe cool spell.

But at the Brazos River site they got lucky. Back in the Cretaceous period this site was covered by a warm sea, said Johan Vellekoop of Utrecht University in the Netherlands and the lead author of the paper. When the giant asteroid hit, a tsunami rolled over the site and covered it with a series of sandy layers. On top of that, the researchers found a thin layer of sediment that is more fine at the top than at the bottom, and it is in this layer that they found lipid evidence of a major cooling.

According to Vellekoop, the story embedded in the rocks goes like this: Initially, the lipids tell us there is a warm climate. Then, the asteroid hits, and a wash of sandy layers from a resulting tsunami arrives. Next, storms and hurricanes churn the ocean waters stirring up sediments in the ocean. Finally, the storms subside. As the seas settle, bigger sediments fall to the seabed first, and the finest sediments fall last. Embedded in this layer are the lipid evidence of cooler temperatures.

In other words, it seems the computer models were right — and evidence of the impact winter has been found at last.

Flickr via Rupert Taylor-Price

Small Microbes Almost Killed All Life On Earth, Study Suggests

By Deborah Netburn, Los Angeles Times

LOS ANGELES — Tiny microbes on the bottom of the ocean floor may have been responsible for the largest extinction event our planet has ever seen, according to a new study.

These microbes of death were so small, that one billion of them could fit in a thimble-full of ocean sediment, and yet, they were almost responsible for killing off all the life on our planet, the scientists suggest.

The end-Permian extinction was the most catastrophic mass extinction the Earth has ever seen. It started roughly 252 million years ago — long before the dinosaurs — and it continued for 20,000 years. By the time it was over, nearly 90 percent of all life on Earth had been destroyed, the scientists say.

“It was not as dramatic as the impact that probably killed the dinosaurs, but it was worse,” said Gregory Fournier, an evolutionary biologist at MIT. “Things were very close to being over for good.”

Scientists have struggled to understand exactly what caused the long, slow, mass die-off in this dark era of our planet’s history. The geologic record tells us there was a sharp uptick of C02 levels at the time. That would have caused the oceans to acidify and the Earth to heat up, making the environment inhospitable for most forms of life. But what actually caused the C02 levels to rise has remained a mystery.

Some scientists have suggested an asteroid impact could be to blame; others have proposed that volcanic activity or coal fires might be the culprit.

Now, in a paper published this week in PNAS, researchers from the Massachusetts Institute of Technology and the Chinese Academy of Sciences in Nanjing, China, have fingered a new and unlikely suspect — a tiny methane-spewing microbe known as Methanosarcina.

The first clue that microscopic microbes could be involved in the greatest die-off the Earth has ever known came when MIT geophysicist Dan Rothman was looking at how carbon levels grew during this time. What he saw was not a straight line, but rather a rapid upward curve.

“The growth was like what you might see in a real estate bubble, or a financial bubble,” he explained. “If the C02 came from the sudden combustion of a coal field in Siberia it wouldn’t behave this way. It has this special character that is consistent with microbial processes.”

It was the first time anyone had suggested microbes might be involved with the end-Permian extinction, but far from the first time that microbes have been accused of changing the chemistry of our planet. For example, photosynthetic microbes are responsible for creating the first oxygen in the Earth’s atmosphere.

“It is absolutely normal that microbes are mediating the great elemental cycles,” said Rothman. “What they do is crucial. And if they do better or worse, things change.”

Fournier put it this way: “Microbiologists like to say, ‘Microbes rule the Earth, and we just live on it.’”

To figure out which specific microbe might have a hand in this ancient catastrophe, Rothman took his research to Fournier, who had published a paper about Methanosarcina in 2008. The paper showed that sometime in the last 400 million years, Methanosarcina was the recipient of a gene transfer that allowed it to produce methane more efficiently than ever before.

After seeing Rothman’s analysis, Fournier worked to date the time of the gene transfer more specifically and found it most likely occurred about 250 million years ago.

Although the researchers cannot say for certain that the microbe and the vast quantities of methane it produced were responsible for the end-Permian extinction, they do have one more line of evidence to support their hypothesis. In order to turn acetate into methane, Methanosarcina needs nickel.

“Even if they had all the food in the world they would be limited if they were starved for nickel,” Fournier said.

But if there was a lot of nickel around, the microbes would be unhindered. And, wouldn’t you know, much of the volcanic activity at the time occurred around the Siberian traps, which has some of the world’s largest deposits of nickel. Further more, the researchers found an increase in nickel in sediments from that time.

“Our proposal is unusual, but it does bring together many observations, and ties a lot of stuff together,” Rothman said. “That doesn’t make it right, but it is consistent, and that’s what is necessary to move forward and provide further tests.”

 

Women Can Get HIV From Other Women During Sex, CDC Reports

By Deborah Netburn, Los Angeles Times

The first confirmed case of a woman contracting  HIV from another woman during sex was reported by the Centers for Disease Control and Prevention this week.

Although there have been reports of women transmitting the human immunodeficiency virus to other women through sexual activity, they have been difficult to prove. For nearly all the cases, other risk factors were present — including recent sexual contact with men, intravenous drug use, tattooing, piercing or other, potentially risky, behaviors.

This time, the case seems pretty iron-clad.

As outlined in a paper published by the CDC this week, the two women involved were in a monogamous relationship for six months. At the start of their relationship one of the women was HIV-positive, the other was not. The woman who began the relationship HIV negative said it had been 10 years since she had had sex with a man. She did not use intravenous drugs, or get tattoos or acupuncture or transfusions or transplants.

She did, however, occasionally sell her blood plasma, and had tested negative for HIV after donating plasma in March 2012.

Ten days later, she went to the emergency room with an symptoms including sore throat, fever, muscle aches, dry cough, vomiting and frequent diarrhea. She was tested for HIV then, but the results were negative. Two and a half weeks later she went to sell her plasma again. That time she tested positive.

The two women said they had unprotected sex frequently, shared sex toys, and had sex when one of them was menstruating. Their sex also occasionally caused one or the other of them to bleed.

So the CDC concluded that it is rare but possible for a woman to get HIV from a female sexual partner.

The agency recommends that all couples in which one person is HIV-negative and one person is HIV-positive should receive counseling regarding safer sex practices — even if both parties are female.

AFP Photo/Manjunath Kiran

Scientists Identify Oldest Crystal On Earth — 4.4 Billion Years Old

By Deborah Netburn, Los Angeles Times

The oldest known material on Earth is a tiny bit of zircon crystal that has remained intact for an incredible 4.4 billion years, a study confirms.

The ancient remnant of the early Earth may change the way we think about how our planet first formed.

The crystal is the size of a small grain of sand, just barely visible to the human eye. It was discovered on a remote sheep farm in western Australia, which happens to sit on one of the most stable parts of our planet.

“The Earth’s tectonic processes are constantly destroying rocks,” said John Valley, a professor of geoscience at the University of Wisconsin-Madison, who discovered and dated the crystal. “This may be the one place where the oldest material has been preserved.”

The crystal is so much older than anyone expected that Valley and his team have had to date it twice. They published their first paper about this grain of zircon in 2001. At that time they determined it was 4.4 billion years old by measuring how many of the uranium atoms in the rock had decayed into lead.

Geologists have used this technique, known as the uranium lead system, for decades to date rocks on Earth and from space, but because nobody had ever found anything on Earth that was this old, the initial findings were questioned. Maybe, some said, the lead atoms had moved around in the zircon, making it seem like there was more lead and giving the scientists an inaccurate date.

On Sunday, Valley and his colleagues published a paper in Nature Geoscience that proves the zircon is as old as they say. This time around, they used a new method called atom-probe tomography that let them see individual atoms of lead in the sample and see whether they had moved. They found that the lead atoms do indeed move around over time, but on such a small scale that the movement would not interfere with the overall dating process.

“We have a zircon that is 4.4 billion years old,” Valley said.

And now the fun begins, because this small piece of ancient rock has big implications for how and when the Earth’s crust started to form.

Like the rest of the solar system, scientists say, Earth formed about 4.567 billion years ago.

One theory suggests that in the frenzy of those early days 4.5 billion to 4.4 billion years ago, Earth was struck by an object the size of Mars. The impact altered Earth’s tilt and caused a chunk of the planet to vaporize into space; some of that dust later became the moon.

The blow also caused the rest of Earth to be covered in a hot magma ocean. This is called the Hadean period.

Scientists were not sure how long the Hadean period lasted, but this ancient piece of zircon suggests the Earth’s crust had started to cool and form by 4.4 billion years ago.

“What we can say is that 4.4 billion years ago, the continental crust had started for form,” Valley said, “and that the real Hadean period only lasted for a very short time. By 4.4 billion years, it was over.”

Photo: cobalt123 via Flickr