Saturday, 27 February 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

No Lie! Your Facebook Profile Is the Real You

Posted: 26 Feb 2010 03:41 PM PST


"On the Internet," one dog tells another in a classic New Yorker cartoon, "nobody knows you're a dog."

sciencenewsThe internet is notorious for its digital dens of deception. But on Facebook, what you see tends to be what you get — at least in one study of tailless, two-legged young adults.

College-age users of Facebook in the United States and a similar social networking site in Germany typically present accurate versions of their personalities in online profiles, says psychologist Mitja Back of Johannes Gutenberg University in Mainz, Germany. People use online social networking sites to express who they really are rather than idealized versions of themselves, Back and his colleagues conclude in an upcoming Psychological Science.

"Online social networks are so popular and so likely to reveal people's actual personalities because they allow for social interactions that feel real in many ways," Back says.

Back's team administered personality inventories that evaluated 133 U.S. Facebook users and 103 Germans who used a comparable social-networking site. Inventories focused on the extent to which volunteers endorsed ratings of extraversion, agreeableness, conscientiousness, emotional instability and openness to new experiences.

The subjects — who ranged in age from 17 to 22 — took the inventory twice, first with instructions to describe their actual personalities and then to portray idealized versions of themselves.

Then, undergraduate research assistants — nine in the United States and 10 in Germany — rated volunteers' personalities after looking at their online profiles. Those ratings matched volunteers' actual personality descriptions better than their idealized ones, especially for extraversion and openness.

Facebook is so true to life, Back claims, that encountering a person there for the first time generally results in a more accurate personality appraisal than meeting face to face, going by the results of previous studies.

Adriana Manago, a psychology graduate student at UCLA, calls the new findings "compelling" but incomplete. College students on Facebook and other online social networks often augment what they regard as their best personal qualities, Manago holds. In her view, these characteristics aren't plumbed by broad personality measures like the ones measured in Back's study. And students' actual personality descriptions may have included enhancements of their real characteristics, thus inflating the correlation between observers' ratings and students' real personalities, Manago notes.

"Online profiles showcase an enhanced reflection of who the user really is," Manago proposes. In a 2008 study, she and her colleagues found that 23 college students sometimes used another online social networking site, MySpace, to enhance their images, say by Photoshopping acne out of a picture or posting a video of themselves driving a sports car at high speeds.

Still, the new findings make sense, remarks psychologist Sandra Calvert of Georgetown University in Washington, D.C. She emphasizes that social-networking sites have fostered a new type of communication among teens and young adults, in which one person can create personal content that gets broadcast to a multitude of friends.

In a 2009 study of Facebook use among 92 college students, Calvert's team found that young women reported a whopping average of 401 online friends, while young men reported an average of 269.

Image: escapedtowisconsin/Flickr

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Flash-Freezing Technique May Boost Egg Survival Rates

Posted: 26 Feb 2010 03:14 PM PST


A new study has identified the best way to flash freeze living tissue, which could lead to better human egg and stem cell storage.

The technique could dramatically improve the odds that frozen, unfertilized eggs could be thawed out and still be healthy enough to be fertilized. That would reduce how many eggs must be harvested, raising success rates and lowering the number of costly, painful procedures women must endure to get pregnant.

Freezing tissue is so difficult because the water in cells expands as it freezes. "That will mean the cell membrane is ruptured, like the coke you forgot in the freezer that explodes," said bioengineer Utkan Demirci of Harvard Medical School Brigham and Women's Hospital, lead author of the study Feb. 23 in the Proceedings of the National Academy of Sciences.

While oocyte, or egg, freezing is commercially available, the success rate is low, Demirci said.

"With 20 eggs from a female, you pick only two and one of them gets to be fertilized, so it's really important to have the technologies that are going to further the success rate in oocyte preservation," he said.

Preventing frost damage requires surrounding the cells with cryoprotectants, or toxic chemicals like antifreeze, said biomedical engineer Xiaoming He of the University of South Carolina, who was not involved in the study. For sperm cells, which contain very little water, scientists can use smaller amounts of the chemicals. But delicate embryonic stem cells, or large, water-filled cells like eggs require much more protection and are usually damaged during freezing. Using less of the chemicals could help these sensitive cells fare better while frozen in storage.

In previous work, scientists developed a technique to halt ice crystal formation and make the cells glassy instead, a process called vitrification.

"To vitrify a liquid, you have to pull the heat out of a liquid as fast as possible so it doesn't have time to crystallize," Demirci said.

In the technique, droplets of eggs encapsulated in a protectant shoot out into a bath of ultracold liquid nitrogen, at a temperature of -321 F. The relatively hot droplet evaporates nearby nitrogen. The vapor pushes the droplet up, levitating it above the surface for several seconds (see video below). The nitrogen vapor layer also forms a barrier that shields the droplet from the surrounding cold.

Until now, no one had figured out a good way to vitrify cells with low levels of protectants. Hoping to find an answer, Demirci's group analyzed what happened to different sizes of droplets once they were vitrified. After droplets froze and sank back into the nitrogen, they measured the droplets and used a microscope to determine how crystallized they were.

They found smaller droplets were almost completely vitrified, while larger droplets formed damaging ice crystals. That was because the larger droplets had more surface area to prevent heat from escaping, so they froze more slowly, Demirci said. Using smaller droplets of about the width of a human hair prevents the cells from crystallizing, which means they are more likely to survive the process.

The technique raises the chances of eggs making it through the freezing process alive. It can also be automated to freeze millions of cells per second, making it cost-effective, Demirci said.

The team is currently freezing mouse eggs. "Once we can generate some baby mice with this platform, then we are moving forward to use some discarded human eggs," Demirci said.

"It's one of the important breakthroughs in vitrification procedures," said veterinarian and cryobiologist Yuksel Agca of the Unviersity of Missouri-Columbia, who was not involved in the study.

"The downside is that the procedure uses direct injection into the liquid nitrogen," which can sometimes be contaminated. "But there are ways to sterilize liquid nitrogen."

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Image: Human egg/ euthman/Flickr
Video: Droplet levitating on liquid nitrogen/PNAS

Citation: "Vitrification and levitation of a liquid droplet on liquid nitrogen," Young S. Song, Douglas Adler, Feng Xu, Emre Kayaalp, Aida Nureddin, Raymond M. Anchan, Richard L. Maas, Utkan Demirci, Proceedings of the National Academy of Sciences, 22 Feb. 2010.

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Blood-Chilling Device Could Save Stroke Victims From Brain Damage

Posted: 26 Feb 2010 10:19 AM PST


SAN ANTONIO — Cool runnings, indeed. A tiny device placed inside a central vein can safely refrigerate blood as it flows through stroke patients, lowering their temperature and raising the possibility that they might gain brain protection from hypothermia without having to be packed in ice.

sciencenewsAlthough the trial didn't find that stroke patients getting their blood cooled fared any better or worse than a comparison group of patients who weren't cooled, the technology proved safe enough to clear the way for testing the device in a much larger group, said Thomas Hemmen, a neurologist at the University of California, San Diego Medical Center who presented the data Feb. 25 at the International Stroke Conference.

The new results also demonstrate that stroke patients can be cooled down to 91.4 degrees Fahrenheit safely while they are receiving a powerful clot-busting drug called tPA, the standard treatment given to patients during the first few hours of a clot-induced stroke.

"Cool temperatures have been associated with better outcomes," said Daniel Lackland, an epidemiologist at the Medical University of South Carolina in Charleston. "We're seeing some excitement about an intervention with this device." If further trials support use of this kind of cooling therapy, he said, "that would be a great finding — it's a relatively easy thing to do."

Induced hypothermia is mainly used for cardiac arrest patients who have had their hearts restarted but are comatose and risk delivering a shortage of blood to the brain. Because they are unconscious, those patients can be packed in ice.

But stroke patients are awake during treatment, which makes being packed in ice extremely uncomfortable. In the new study, Hemmen and his colleagues teamed with a company called InnerCool Therapies to test a device only a half-centimeter in diameter that causes less discomfort by chilling the blood as it flows through the vena cava, a huge vein that carries blood into the heart from the upper part of the body.

The study included 58 stroke patients who were an average of 66 years old and had been referred to university hospitals around the United States. All of the patients received tPA, and 28 of them were also randomly chosen to get blood cooling. At a checkup 90 days later, seven controls and five of the hypothermia group were judged as having little or no disability — not a substantial difference.

Hemmen said this recovery rate for both groups is worse than the average seen in stroke patients nationwide, because many of the patients referred to this study by physicians had severe strokes and previous medical problems. Patients undergoing cooling were more likely to develop pneumonia during recovery, but this didn't affect their status on average when assessed 90 days after treatment.

Regulators overseeing the study required a one-hour delay from the point at which tPA was given before cooling could be started, which might have limited the benefits of the treatment, Hemmen said.

These preliminary results might rejuvenate the idea of cooling stroke patients. "I kind of thought that hypothermia for stroke had actually gone by the wayside. I'm really pleased it's come back," said neurologist Cheryl Bushnell of Wake Forest University Health Sciences in Winston-Salem, North Carolina. "Overcoming the technological issues of cooling is a major benefit."

The protective effects of cooling are well-documented in incidents of drowned people being revived with little brain damage after falling though the ice on frozen lakes. But the precise biological mechanism responsible for this benefit is poorly understood. Slowing metabolism may limit cell death, Bushnell said.

Hemmen said a randomized trial of 400 first-time stroke patients is being planned that will start cooling and administration of tPA simultaneously.

Image: Seattle Municipal Archives/Flickr

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