Page 1 of 25 123411 ... LastLast
Results 1 to 20 of 496

Thread: Science News

  1. Back To Top | #1

    Science News

    Pe threadul asta sa postati chestii noi si interesante din lumea stiintei (nu exclusiv fizica, ci de toate)

    incep eu :P

    The Theory of Almost Everything by Robert Oerter

    WITH exotic yet unproven physics such as string theory and extra dimensions getting all the hype, the tried and true standard model of particle physics isn't getting the respect it deserves. Physicist Robert Oerter is out to set the record straight, and in this book he reveals the standard model in all its glory. To a physicist, Oerter explains, particles are like the ornaments on a Christmas tree: pretty, but not fundamental. He wants to give readers the tree - the underlying structure. But it's a prickly one: this is an in-depth examination of particle physics, and it can be tough going.

    [ I WANT THAT ]

    The world's 10 biggest ideas

    Certain questions define the way we see the world. How did the universe begin? What is matter made of? What shaped our planet? How did the amazing diversity of life arise? We take many of the answers for granted, but maybe we shouldn't.

    When we asked 10 of the biggest names in science to explain the significance of their discipline we were surprised by their response: who would have thought understanding quantum theory was relevant to the abortion debate? Or that a diamond ring can take you back to Pangaea? Set your mind spinning with our guide to the World's 10 Biggest Ideas...

    Dark-matter basketballs could explain a lot

    THE universe's invisible matter may not be made of exotic unknown particles after all. Instead, "dark" matter could be clumps of the ordinary stuff trapped in a previously unsuspected state of the vacuum of space.

    The dark-matter balls envisaged by Colin Froggatt of the University of Glasgow, UK, and Holger Nielsen of the Niels Bohr Institute in Copenhagen, Denmark, are relics of a vacuum state which theory suggests could have been widespread in the first second after the big bang ( Each ball would not be much bigger than a basketball and atomic nuclei would have formed inside them just as they do everywhere else in the universe, only bound by a stronger nuclear force. The balls would be much denser than ordinary matter, with each one weighing 100 million tonnes.

    To account for the known density of dark matter in the cosmos, there would have to be just one such ball drifting through every volume of space about the size of our solar system.

    The new theory makes one important prediction - that there should be five times as much dark matter as ordinary matter. "That's exactly what is observed," says Froggatt.

    Ben Allanach of CERN, the European centre for particle physics near Geneva, Switzerland, admits the idea is wildly speculative. "But I can't think of anything specifically to rule it out," he says.

    + Later edit: added 404 Not Found @ 02:10 AM pe thread "Teoria Stringurilor"

    ++ Later edit

    MSG - The Slow Poisoning Of America

    MSG Hides Behind 25+ Names, Such As 'Natural Flavouring' MSG Is Also In Your Favorite Coffee Shops And Drive-Ups
    Last edited by SF; 15-09-2005 at 01:11.

  2. Back To Top | #2
    Thyristors go organic

    Physicists in Japan have made a thyristor -- a device that can convert a direct current into an alternating current -- from a single crystal of organic material. In addition to practical applications, the device could be used to explore fundamental aspects of condensed matter systems (Nature 437 522).

    Thyristors are devices that can switch between two different conductance states and they are widely employed to control electric currents in applications such as motors and refrigerators. A conventional thyristor consists of a series of diodes. Ichiro Terasaki of Waseda University and colleagues have now discovered an organic material that exhibits similar behaviour in its bulk state.

    The Japanese team made its device from an organic conducting salt known as θ-(BEDT-TTF)2CsCo(SCN)4, which consists of alternate layers of BEDT-TTF, which is a conductor, and CsCo(SCN)4, which is an insulator. At low temperatures, the conduction electrons in the crystals exhibit a high resistance as a result of "charge ordering".

    When a current is applied to the crystal, the charge order immediately "melts", causing the resistance to decrease rapidly as the current increases. This means that that the crystal has essentially the same characteristics as a conventional thyristor, although the mechanism is different. The Japanese team showed that the device can convert a small applied direct current into an alternating current with a frequency of 40 Hz.

    "The charge-ordered state is a kind of 'ice' of conduction electrons and thus we may say that current melts the ice," explains Terasaki. "On a cold day, water on a pond is frozen but water in a river still flows - our finding is a similar phenomenon in solids."

    The team plans to use the material to explore non-equilibrium phenomena in general. The experiments were all carried out at low temperatures, so Terasaki and co-workers hope to find organic materials that exhibit thyristor-like behaviour at room temperature. They also plan to search for inorganic single crystals with similar properties.

    100 years after E=mc2

    Even a century after Albert Einstein conjured up his world-changing equation, the nature of most of the universe still eludes us

    WHEN physicist Stephen Hawking starting writing his bestseller A Brief History of Time, he was warned that including just a single equation would halve the sales of his book. Despite the financial implications, Hawking felt compelled to include one, E = mc2, underlining the iconic status of Albert Einstein's famous formulation.

    The equation, published exactly 100 years ago this week, has come to symbolise the upheavals of early 20th-century physics. Einstein's theories of relativity, along with quantum physics, changed our ideas of space and time, cause and effect, and spawned theories for everything from the big bang to black holes. For decades, relativity and quantum mechanics have provided the foundation for modern physics.

    Now this foundation is cracking. Enigmatic discoveries of dark matter a few decades ago and of dark energy a few years ago have thrown physics into turmoil. Nearly 96 per cent of the universe is made of ...
    The complete article is 3219 words long.

  3. Back To Top | #3
    Mathematics Unites The Heavens And The Atom
    In recent years, mathematicians have discovered an almost perfect parallel between the motion of spacecraft through the solar system and the motion of atoms in a chemical reaction - a hidden unity that has led to innovative new ways to design space missions.

    Unii sunt de parere ca ar trebui sa...
    Explain physics with the whole instead of particles
    Physicists usually describe the world from the vantage point of its smallest component parts. But quantum theory does not allow itself to be conceptually crammed into such a framework. Instead, in her dissertation at Uppsala University in Sweden, Barbara Piechocinska takes her point of departure in the mathematics of the dynamic whole and finds that time thereby takes on new meaning.

    dar culmea ca totusi....
    Manipulation of single atoms provides fundamental insights
    It seemed like science-fiction just a few years ago, but is now common practice for scientists at the Paul Drude Institute for Solid State Electronics (PDI) in Berlin. The scientists manipulate single atoms resting on surfaces and assemble them into wires or tiny clusters. In the world of nanometric dimensions, fundamental material properties such as magnetism, electrical conductivity or chemical reactivity differ from the conventional behaviour observed in everyday life.

  4. Back To Top | #4
    Quantum information teleported between distant atoms

    New technique can move fragile quantum data between atoms without destroying it

    A qubit walks into a bar, unsure of whether to order drink A or drink B. If the bartender asks the qubit what it wants, the qubit will collapse and be destroyed. But now researchers can instantly teleport the original, intact qubit to another “bar” far away.
    In the Jan. 23 Science, a team is reporting what is the first successful transfer of a qubit — an undecided bit of quantum information — between two widely separated, charged atoms. Because the quantum information instantly hops from one atom to the other without ever crossing the space between the two, scientists call the transfer “teleportation.”
    Being able to teleport such information between atoms could aid the development of ultrafast quantum computers and extremely secure quantum communication, the researchers point out.
    “The catch with quantum information is that you can’t read it without destroying it,” says study coauthor Steven Olmschenk, a physicist at the University of Maryland in College Park. “Somehow you have to send it from one point to another without ever having read it.”
    To read the quantum information contained in an atom or a photon, scientists must measure some property of that particle. But in the quantum world, the act of measuring a particle alters it. Until it’s measured, an atom or photon can remain in an ambiguous state of all possible values simultaneously. Whenever a particle is measured, though, this range of possibilities “collapses” into a single, distinct value. The original, uncommitted state is lost, and it’s this ability to hold multiple values at once that gives qubits such potential for high-performance computing.
    Scientists have previously teleported unmolested qubits between photons of light, and between photons and clouds of atoms. But researchers have long sought to teleport qubits between distant atoms. Light’s high speed of travel makes photons good transporters of information, but for storing quantum information, atoms are a much better choice because they’re easier to hold on to.
    “This is a big deal,” comments Myungshik Kim, a quantum physicist at Queen’s University Belfast in the United Kingdom. “To store information as it is in quantum form, you have to have a teleportation scheme available between two stationary qubits. Then you can store them and manipulate them later on.”
    To teleport the qubit, Olmschenk’s team first linked the fates of two charged atoms of ytterbium, which were suspended in a vacuum chamber by electric fields. Zapping one of the atoms with a microwave pulse excited an electron in that atom, thus putting that electron into a mixture of two possible states. Researchers then zapped each atom with an ultrafast laser that caused each atom to emit a single photon of light. The wavelengths, or colors, of these photons depended on which states the electrons were in. Crossing these photons in a beamsplitter sometimes entwined the states of those electrons, a bizarre quantum phenomenon called entanglement.
    When two particles become entangled, their separate quantum identities get blended so that a single equation represents both. So entangling the two electrons caused the original qubit — the unknown, unresolved mixture of two possible states — to become essentially shared between the two atoms.
    The researchers then measured the first atom, thus destroying the delicate quantum information it contained, and also destroying the entanglement. That left the original qubit intact in only the second, recipient atom, completing the teleportation.
    While the work marks a fundamental achievement in manipulating quantum information, Eugene Polzik, a physicist at the Niels Bohr Institute in Copenhagen, notes that the efficiency of the procedure is still too low to be useful. Currently, only about one out of every 100 million attempts results in a successful entanglement, though Olmschenk says this rate could be significantly improved.
    “This very low efficiency is partly due to technical reasons,” such as a small lens for capturing photons released by the atoms and low detection efficiency for those photons, Polzik comments. “It is nonetheless a spectacular achievement.
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  5. Back To Top | #5
    Possible anticancer power in fasting every other day

    When mice ate as important as what they ate in reducing cell division linked to cancer

    Fasting every other day reduces some hallmarks of cancer in mice, even when the mice voraciously consume high-fat food between fasts, a study in an upcoming Nutrition shows.
    Scientists have known for decades that eating fewer calories — roughly 25 to 50 percent less than recommended — extends life span in animals ranging from worms to dogs. But, “caloric restriction on a daily basis is very hard,” says Eric Ravussin, a physiologist at the Pennington Biomedical Research Center in Baton Rouge, La., who studies caloric restriction.
    Last year, researchers including Krista Varady, then of the University of California, Berkeley, published a study suggesting that a less drastic version of caloric restriction provides a constellation of health benefits in mice. Called alternate-day fasting, the regimen of eating as much food, low-fat in this study, as one wants one day but fasting the next confers some of the same anticancer benefits as just cutting calories at a constant rate, the team found.
    But for people, eating a low-fat diet one day and fasting the next is still challenging. Varady and her colleagues wanted to know whether the diet could be made easier to swallow and still provide similar benefits.
    In the new study, Varady and other researchers compared mice who fasted every other day, both on high-fat and low-fat diets, to mice that didn’t fast but instead ate a low-fat diet every day. The mice on the ultimate yo-yo diet ate high-fat food, in which 45 percent of the calories came from fat — comparable, Varady says, to human diets of fast food and processed food.
    On the fasting days, mice were fed 15 percent of their required calories from either the high- or low-fat food.
    The results were surprising, says Varady. Mice that ate the rodent equivalent of Big Macs every other day showed the same anticancer benefits of fasting as the mice that ate the low-fat diet every other day. High rates of cell division — a key feature of cancer — were lower in the mice who fasted every other day than in mice that had not fasted. Mice who fasted every other day also had reduced levels of IGF-1, a protein that induces cell growth and has been linked to cancer.
    The new study on mice is the “next installment in a systematic and interesting series of studies” from the researchers, comments James Johnson, a doctor affiliated with the Louisiana State University Health Sciences Center and studies alternate-day fasting in humans.
    The option to eat high-fat meals while fasting every other day may make people more likely to stick with the demanding diet regimen, researchers say. To date, only three small studies have examined the effects of alternate-day fasting on people, says Varady, now at the University of Illinois in Chicago.
    She says the next step is to see whether an unrestricted high-fat diet one day and a small amount of food the next will confer the same health benefits in humans as it does in mice. Varady and her colleagues are currently conducting a study to test whether humans are able to stick with such a diet. Preliminary data suggest that they can.
    “The alternate diet has a lot of potential,” comments Valter Longo, a University of Southern California in Los Angeles researcher who studies aging. But, he adds, “I seriously doubt that very many people would adopt it because it is very tough to do regularly.”
    Ravussin knows the difficulty firsthand. When he attempted alternate-day fasting himself, he reported feeling very irritable and hungry. “My wife told me, ‘Don’t do it again.’ ”
    Editare ulterioară
    A honeybee tells two from three

    Dots, lemons, leaves or blobs — honeybees know when they see three

    Honeybees know a thing or two, or three. Even when tricky scientists make those things look different.
    Teach a honeybee to recognize two blue dots and she can then find two star or lemon icons or even a mixed picture of a lemon and a flowerlike purple blob, says a new study.
    Bees can use their visual sense of number to generalize from one kind of image to another, says Shaowu Zhang at the Australian National University in Canberra.
    In picking out the right number of elements, bees aren’t taking any of the numerical shortcuts the researchers tested. For example, the bees aren’t just looking at total area, position or outline shape of the grouping, Zhang and his colleagues report online January 27 in PLoS ONE.
    “This is the first report of visual generalization of number in honeybees,” Zhang says. “I have been studying honeybees since 1980, and I am often surprised by our experimental results. The bee is smart.”
    TESTING NUMBERSTo test a honeybee’s numerical powers, researchers sent the bee down a tunnel and through a hole marked by a reference pattern. When the bee passed through the first hole and into the choice chamber, she had to choose the exit marked with the same number of elements she'd just seen in the reference pattern.Gross et al. 2009. PLoS ONE 4(1): e4263

    What animals can do with numbers has intrigued biologists studying the evolutionary roots of cognition. Experiments based on selecting same-number patterns have shown some kind of numerical ability in birds, primates, dolphins, raccoons and even salamanders.
    Such experiments have tested many more vertebrates than invertebrates though. Honeybees seemed like good candidates for study, the researchers say, because other recent research has found evidence of some fancy bee cognition. Bees can learn sameness and difference, for example. Coauthor Jürgen Tautz of the University of Würzburg in Germany predicts “astonishment of experts and laymen alike” at the sophistication of the tiny honeybee.
    The new test represents a useful extension of earlier work, says bee scientist Lars Chittka of Queen Mary, University of London. His research has shown that bees can count off landmarks to reach a destination and a reward.
    To see whether bees can take what they learn about number from one kind of icon and apply it to different ones, Zhang and Tautz’s labs trained bees to fly through a little tunnel with a choice of exits.
    In the tests, a bee zoomed along a meter of tunnel and then through a hole marked with a reference pattern, such as two blue dots. Once through the hole, the bee had to choose between two exits, each marked with a pattern. If the bee chose the exit marked with the same number of elements as the reference pattern, she ended up in a little chamber with a reward.
    Researchers trained about 20 bees to distinguish between two or three blue dots. Bees plateaued at about 70 percent correct choices. The researchers then presented the bees with increasingly tougher challenges. One reference pattern with three dots led to a choice between different patterns, either two fat dots or three skimpy ones, having the same total areas. Or bees had to choose the right number of elements even when researchers used confusing icons.
    Bees could distinguish between two and three, and could also tell between three and four when matching to a three-element pattern. But presenting a four-element pattern was going a little far. This time bees didn’t distinguish between four and three.
    Before any humans get too smug, the researchers point out that memory studies have suggested that the number of things a person can consciously remember at any one time is typically around — four.
    Zhang and Tautz aren’t saying that the bees count to two or three in the human sense. Even if scientists expected bees and humans to have such similar cognitive processes, demonstrating bee counting would take some remarkable cross-species mind reading.
    Chittka says the strategy of extracting a visual sense of “twoness” or “threeness” from an image and applying it later might actually be a strategy to economize on memory. “It might require less ‘storage space’ to just remember a feature by which you can identify several relevant targets,” he says.
    “So while many researchers still adhere to the view that smaller brains automatically mean ‘less intelligence,’ the opposite might sometimes be the case,” Chittka says. Honeybees might be getting by with less memory capacity because they use clever strategies like categorization.
    Last edited by sirAdrian; 28-01-2009 at 12:32. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  6. Back To Top | #6
    I feel your pain, even though I can't feel mine

    Pain-insensitive people probably rely on emotional regions of the brain for empathy

    In 1985, Monday Night Football fans looked on as Washington Redskins quarterback Joe Theismann was sacked. The collision was so forceful that it snapped Theismann’s leg, breaking like, as one fan put it, a “stale chopstick.” Most audience members likely empathized with Theismann’s pain, including people afflicted with a rare disorder that prevents them from feeling pain themselves, a new study suggests.
    Instead of using past experiences of feeling pain to commiserate, such people likely rely on the ability to imagine the pain of others, suggests the brain-imaging study, published online January 28 in Neuron.
    “This fascinating and well-conducted study” gives new insights into the relationship between pain and empathy, comments Marco Loggia of the Athinoula A. Martinos Center for Biomedical Imaging in Charlestown, Mass.
    The study suggests that multiple brain regions, including regions involved in emotions, can be recruited to feel empathy for others’ pain. In future studies, Loggia says, it would be interesting to examine other cases when people are exposed to someone else’s feelings without ever having felt such feelings firsthand. “How can humans empathize with a dog that hurt its tail? How can a man understand menstrual pain?” Loggia asks. The answers, he proposes, may lie in the same regions of the brain that allow pain-insensitive people to empathize with others’ pain.
    Study coauthor Nicolas Danziger wanted to know whether a person could empathize with an unfamiliar emotional state. Understanding other people’s emotional states, such as pain, is thought to be based on a system in the brain called the mirror system. When someone sees a quarterback break a leg, specific groups of brain cells in the spectator’s brain activate. These nerve cells are the same ones that would activate if the spectator broke his own leg.
    Called mirror neurons, these cells are thought to prompt a kind of knee-jerk reaction in the brain in response to seeing others’ pain, a phenomenon researchers call automatic resonance. Put simply, these mirror brain cells don’t distinguish between monkey see and monkey do.
    The activity of whole groups of interconnected neurons in one person can mirror that of whole groups of interconnected brain cells in another person, a process called “mirror matching.” Now, scientists know that entire mirror neuron systems can respond to others’ emotions, such as disgust. Seeing a disgusted person elicits mirror matching in the brain of the watcher, where the same group of nerve cells activates as if the watcher were disgusted himself.
    Some researchers had proposed that mirror neurons would not exist or not respond correctly when a person witnessed an unfamiliar sensation. To test this idea, Danziger, a neurologist in the Pain Center at the Pitié-Salpêtrière Hospital in Paris, recruited a unique group of subjects.
    Some people are born with rare genetic defects rendering them completely insensitive to physical pain. Danziger’s team used fMRI techniques to study the brain responses of such people as they gazed at physically painful situations.
    Subjects were shown images of a finger caught in a pair of shears and of a man’s face screwed up in a painful expression. The brains of control subjects who feel pain normally showed activation patterns in two pain-sensing brain regions, the anterior mid-cingulate cortex and the anterior insula.
    As it turns out, these pain-sensing regions were similarly activated in the subjects who could not feel pain. “Our first intuition is that we were expecting a huge difference between the two groups. We saw the contrary,” says Danziger.
    The results suggest that these brain responses are not mirror matching systems for pain. However, the similarity of brain activation in these regions doesn’t rule out possible mirror matching in other brain regions, says Danziger.
    Brain regions like the amygdala, important for emotional processing, might harbor a mirror matching system for pain, he says. The researchers couldn’t assess amygdala activation, due to fMRI interference from nearby bone.
    It was in the midline brain structures that the team noticed differences between pain-insensitive subjects and control subjects. When they were able to empathize with others’ pain (as judged by a questionnaire), people insensitive to pain relied heavily on activity in these regions (parts of the prefrontal cortex and the ventral posterior cingulate cortex) involved in formulating emotional perspectives. Only pain-insensitive subjects with high empathy scores had high activity in these brain regions, whereas in control subjects, activity in these regions had little to do with the amount of empathy.
    Pain-insensitive people “can only rely on the emotional regions,” says Danziger. “It’s far from automatic.” These people may be relating the physical pain they witness to emotional pain they have felt themselves.
    Most likely, the midline brain structures, places where Danziger says “emotional work” is done, and the mirror matching systems both play a role in empathy in regular people.
    “I think both mirror neuron areas and midline areas are important for intersubjectivity,” comments Marco Iacoboni, a neuroscientist studying mirror neuron systems at the University of California, Los Angeles.
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  7. Back To Top | #7
    Donating a kidney doesn't hurt long-term health

    In fact, occurrence of end-stage renal disease is lower among donors

    Minnesota native Anthony Thein didn’t hesitate back in 1967 when doctors asked him to donate a kidney to his ailing brother. “If you think it might help somebody survive, you say, ‘Yes, of course,’ ” Thein says.
    But kidney transplants from living donors were still uncommon in the late 1960s, and the operation carried risks for both parties. Doctors didn’t know whether living with just one kidney could entail long-term medical repercussions.
    “Yeah, we really did something crazy 42 years ago,” Thein says today.
    Perhaps not. Researchers report in the Jan. 29 New England Journal of Medicine that people who donate a kidney have about the same probability of survival over several decades as people in the general population. And donors seem to have adequate kidney function and even less risk of severe kidney disease than occurs in the general public, , nephrologist Hassan Ibrahim of the University of Minnesota and his colleagues report.
    To arrive at these findings, the researchers pored over a database of kidney transplants performed at the University of Minnesota between 1963 and 2007 and tried to reach as many of the donors as possible. Using this data and death records from the Social Security Administration, the scientists were able to asses the mortality rate among 3,698 people who gave away a kidney within that time span.
    The survival curves of these donors and the general public are close, even favoring the donors slightly. And the rate of end-stage renal disease, which necessitates dialysis and can put a person on a waiting list for a new kidney, was lower among the donors than in the general population.
    The researchers also randomly selected 255 of the donors to undergo kidney function tests between 2003 and 2007. The team compared those results against tests done on a group of people who had both kidneys and who matched the donors in race, gender, body weight and age.
    An analysis showed the donors had acceptable measures of basic kidney functions and even outperformed the control group on blood pressure measurements, says Ibrahim.
    Self-reported information suggested the donors had a slightly better overall quality of life than people in the general population.
    To be eligible to donate a kidney, a person must pass a physical examination and cannot have diabetes, high blood pressure or other serious ailments.
    With that in mind, it’s not surprising that kidney donors would have good mortality rates and better health-related quality of life than people in the general population, say physicians Jane Tan and Glenn Chertow of Stanford University School of Medicine, writing in the same NEJM issue. ”Nevertheless,” they note, “it is somewhat surprising and quite reassuring that rates of end-stage renal disease were also lower in kidney donors than in the general population.”
    These broader findings have been reflected in a personal way in Anthony Thein’s life. Now 70 and semiretired, Thein says he hasn’t encountered any problems from lacking a kidney, although he does sport a sizable scar across his midsection — a testament to being among the earliest donors. Donors’ scars today are much smaller.
    “Actually, I’m proud of my scar,” he says. “It’s sort of like a badge of honor.”
    Editare ulterioară
    Parenting shapes genetic risk for drug use

    Drugs have a heightened appeal for teens who inherit a certain gene variant, unless the youngsters also have involved, supportive parents

    Good parenting provides a potent buffer against some youngsters’ genetic predisposition to use alcohol, cigarettes and marijuana by age 14, a new study finds. Uninvolved, unsupportive parenting heralds a spike in consumption of these substances among genetically vulnerable teens, reports a team led by psychologist Gene Brody of the University of Georgia in Athens.

    Brody and his colleagues conducted what to their knowledge is the first long-term examination of how parenting practices combine with a child’s genetic makeup to either prompt or prevent early drug use. Their results, based on a three-year study of rural, black youths from working poor families, a population that Brody’s Center for Family Research works with regularly, appear in the February Journal of Consulting and Clinical Psychology.

    “Our study emphasizes that there are protective processes in children’s lives, such as effective parenting, that shield them from a genetic risk for early substance use,” Brody says.

    His team focused on variations in the serotonin transporter gene, or 5HTT. This gene assists in regulating transmission of serotonin, a chemical messenger in the brain. Many people carry two copies of a long version of 5HTT. But approximately 40 percent of people inherit either one or two copies of a short version of the gene. Having at least one short version lessens serotonin transmission, relative to two long versions.

    A growing number of studies suggest that a short version of the 5HTT gene aggravates people’s responses to psychological stress of various kinds, remarks Avshalom Caspi, a psychologist at Duke University in Durham, N.C. Caspi and his Duke colleague Terrie Moffitt directed a 2003 investigation that first implicated a combination of the short 5HTT gene and childhood abuse in the development of adult depression.

    More than 30 studies since then have looked at how the serotonin-transporter gene’s short version and stressful events contribute to later depression. The results have been mixed.

    “Stress reactions in people with this genetic variation can take multiple forms and may include not only depression but, among adolescents, drug use,” Caspi says. The new results support this scenario, he adds.

    In the new study, black experimenters interviewed 253 youngsters in their homes about past drug use and interviewed their mothers about parenting practices. Youngsters were randomly selected from lists of 11-year-old public school students in four counties.

    Follow-up interviews occurred annually until youths reached age 14. DNA was then obtained from samples of each youngster’s saliva.

    About 43 percent of the students carried either one or two copies of the serotonin-transporter gene’s short version.

    Approximately 5 percent of the 11-year-olds, regardless of genetic makeup, reported that they had smoked cigarettes in the past year. Another 12 percent had occasionally drunk alcohol, less than 1 percent had consumed three or more alcoholic drinks at one time and virtually none had smoked marijuana.

    By age 14, 21 percent of teens reported having smoked cigarettes in the past year, 42 percent had occasionally drunk alcohol, 5 percent had consumed three or more alcoholic drinks at one time and 5 percent had smoked marijuana.

    Among youngsters who carried at least one copy of the short serotonin transporter gene and lived with parents identified as highly uninvolved, the rate of overall drug use increased 21 percent from age 11 to 14. That figure reached only a 7 percent increase among genetically vulnerable youths who lived with highly involved, emotionally supportive parents.

    Influences other than parenting quality apparently affected the habits of youths with a low genetic risk for drug taking, Brody says. In that group, substance use increased by a modest 5 percent for teens living with highly involved, supportive parents but stayed relatively stable for those living with uninvolved parents. Kids with and without the genetic risk may be sensitive to different environmental influences on drug use, Brody suggests.
    Last edited by sirAdrian; 30-01-2009 at 10:14. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  8. Back To Top | #8
    Excess blood sugar could harm cognition

    Study links persistently high readings to poor performance in older people who have diabetes

    Chronically elevated blood levels of the simple sugar glucose may contribute to poor cognitive function in elderly people with diabetes, a study in the February Diabetes Care suggests. But whether these levels add to a person’s risk of developing dementia is unclear, the study authors say.
    People with diabetes face a risk of old-age dementia that’s roughly 50 percent greater than those without diabetes, past studies have shown. Research has also hinted that surges in blood sugar might account for some of that added risk. Many previous studies have tested for elevated blood glucose by obtaining a snapshot blood sample taken after a person has fasted for a day.
    In the new study, Tali Cukierman-Yaffe, an endocrinologist at Tel-Aviv University and McMaster University in Hamilton, Canada, teamed with an international group of colleagues to assess blood glucose levels in nearly 3,000 diabetes patients by measuring A1c, shorthand for HbA1c or glycosylated hemoglobin. Since sugar in the blood sticks to the hemoglobin protein in red blood cells, the A1c test reveals an average sugar level over two or three months.
    In addition to collecting these blood glucose readings, the scientists also asked each volunteer to take a 30-minute battery of four standardized tests designed to assess memory, visual motor speed, capacity for learning and managing multiple tasks.
    On average, the participants were 63 years old at the time they entered the study, had blood drawn and took the cognition tests. Advancing age is known to hamper performance on such tests. After accounting for patients’ ages, the researchers found that people with higher A1c levels fared slightly worse on the tests than those who had lower A1c scores and therefore lower blood sugar.
    After further adjusting for several factors that might affect cognitive performance — including heart disease, education level, alcohol use and depression — a high A1c score was still associated with poorer performance on one of the tests, which measured a wide array of cognitive functions.
    Cukierman-Yaffe cautions that this study shows an association between high A1c and poorer scores on cognition tests, but doesn’t prove that reducing A1c levels will slow the rate of cognitive decline in a person with diabetes.
    Even so, says neuropsychologist Adam Brickman of Columbia University, “there is now converging literature that implicates uncontrolled blood glucose levels with poor cognitive aging. While the mechanisms underlying that are still unclear, there have been enough … studies now to really raise our eyebrows.”
    A key problem in assessing blood sugar’s role in cognitive decline is sorting out the multiple other factors that might also affect such decline, says psychologist Lawrence Fisher of the University of California, San Francisco. “Alcohol use, depression and other things are thought to influence cognitive functioning as well,” he says. “It’s really hard to partition out what the exact effect of each is.”
    The good news is that A1c levels can be lowered with exercise, better diet and use of medication. “These are lifestyle factors that can be modified probably more easily earlier in life than after a diagnosis of dementia,” Brickman says.
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  9. Back To Top | #9
    When dreams come true

    People interpret dreams in ways that affect their waking lives, especially when those dreams support pre-existing beliefs

    Dreams don’t just bubble up at night and then evaporate like morning dew once the sun rises. What you dream shapes what you think about your upcoming plans and your closest confidants, especially if nighttime reveries fit with what’s already convenient to believe, a new report finds.
    In an effort to understand whether people take their dreams seriously, Carey Morewedge of Carnegie Mellon University in Pittsburgh and Michael Norton of Harvard University surveyed 149 college students attending universities in India, South Korea or the United States about theories of dream function.
    People across cultures often assume that dreams contain hidden truths, much as Sigmund Freud posited more than a century ago, Morewedge and Norton report in the February Journal of Personality and Social Psychology. In fact, many individuals consider dreams to provide more meaningful information regarding daily affairs than comparable waking thoughts do, the two psychologists conclude.
    Ideas that dreams come from the brain’s random output or are essential for daily problem-solving or for weeding out the routine clutter in one’s mind appeal to a minority of people, the scientists say.
    In a series of experiments, the researchers also probed interpretations of various real and imagined dreams in a national sample of 270 people surveyed online, 656 commuters and pedestrians interviewed in Boston and Cambridge, Mass., and 60 college students.
    “Our results suggest that the dreams most likely to affect our daily lives and relationships are the dreams that accord with our existing beliefs and desires,” Morewedge says.

    In one experiment, participants reported feeling closer to a personal friend after imagining a dream in which their friend defended them, versus imagining a dream in which that friend betrayed them. In considering actual past dreams about friends, volunteers deemed especially meaningful those dreams that had portrayed their friends positively. Dreams of disliked individuals were rated as particularly meaningful if those dreams showed them in a negative light.
    “This is very good evidence that dreamed-of actions can result in a self-fulfilling prophecy,” comments psychologist Mark Blagrove of Swansea University in Wales. So a person who dreams about a loyal friend may then act in ways that encourage the friend to behave as in the dream.
    A further experiment found that imagined dreams about communications from God were regarded as more meaningful by religious believers than agnostics. Still, agnostics said they would see more meaning in a dream of God commanding them to do something enjoyable, such as traveling the world, rather than unpleasant, such as working in a leper colony for a year.
    Highly negative dreams about death and injury also carry a lot of meaning, the researchers note. In one of their experiments, participants reported being equally reluctant to fly after imaging a dream about a plane crash or learning of an actual plane crash. Volunteers who believed that dreams contain hidden truths reported a particularly pronounced aversion to flying after having imagined a dream about a plane crash.
    People regard thoughts that seem to “come from nowhere,” such as dreams and daydreams, as more meaningful than thoughts with a presumed external cause, Morewedge proposes. People tend to think these unbidden thoughts have been generated for some internal reason related to one’s actual intentions or attitudes, in his view.
    Still, the results don’t explain why cultures around the world regard dreams as highly meaningful, remarks psychologist G. William Domhoff of the University of California, Santa Cruz. In his studies, he finds that dreams are experienced as real while they happen because they frequently simulate waking ideas and concerns. In some cases, a dream seems so real to dreamers that they can’t shake the suspicion that it really happened.
    In the late 19th century, anthropologist Edward Tylor argued that the spirit world partly had its origins in such dreams. “For most cultures, dreams are the soul wandering at night, or other souls visiting us,” Domhoff says.
    Further research needs to examine whether people sometimes experience genuine insights into waking life from dreams, thus encouraging a belief that dreams contain hidden meanings, Blagrove adds.
    Editare ulterioară
    Nemo could get lost again in more acidic seawater

    Finding the right reef to call home might get difficult in future oceans

    Nemo might get lost again as acidifying seawater upsets the way young fish smell their way to a home, according to a new study.
    A little like the animated movie-star clown fish, Nemo’s real-life counterparts go out to sea upon hatching and some 12 days later must find their way back to a reef to settle down in an anemone home. No large-personality pals with celebrity voices advise them, so real fish larvae seem to rely on scents in the water and possibly sounds from reefs when picking a locale.
    In new lab experiments, though, orange clown fish larvae didn’t respond normally to scent when researchers reared them in seawater pushed closer to the acidic side of the scale, says Philip Munday of James Cook University in Townsville, Australia. Ocean chemists predict that the current increase in atmospheric carbon dioxide from human activity is lowering the pH.
    In conditions projected for the end of the century, clown fish larvae might have trouble picking out scents in the water and finding the right habitats, he and his colleagues report online February 2 in Proceedings of the National Academy of Sciences.
    Other marine creatures follow scents and may also face the risk of disorientation with changing ocean chemistry, Munday says. “This is something we should at least be thinking about,” he says.
    Plain seawater today at his lab averages around 8.15 on the pH scale, says Munday, so it isn’t technically acidic (below pH 7 on a scale that goes to 14). Nor is global seawater projected to turn literally acid in the foreseeable future. Yet biologists in recent years have said that relatively small shifts in pH can change life considerably for ocean creatures.
    The seas have picked up around a third of the human-made carbon dioxide released into the air since the industrial revolution began. And ocean water worldwide has dipped by about 0.1 on the pH scale, according to studies cited by Munday’s team. Estimates push the pH down another 0.3 to 0.4 units by 2100 if atmospheric carbon dioxide concentrations reach 1,000 parts per million. That could happen in one of the business-as-usual scenarios for human activity.
    The new research is “the kind of study we need,” says fish ecologist Steve Simpson of the University of Bristol in England.
    To check effects of changing pH, Munday’s lab worked with colleagues from Moscow and Oslo to raise larval clown fish in tanks of seawater lowered to either pH 7.8 or 7.6.
    When raised at 7.8, predicted for the year 2100, clown fish larvae grew what looked like normal sensing organs. And the little fish still had relatively normal attractions to the scents of anemones or adult clown fish that were not their parents
    Yet these larvae reversed some preferences, liking the pungent oils from Melaleuca swamp trees, which they normally avoid. Also, the larvae preferred their parents’ scents to plain seawater. The normal distaste for parental scent may play a role in avoiding inbreeding, Munday suggests.
    When raised in 7.6 pH seawater, projected for around 2200, clown fish didn’t show any scent-following behavior.
    This work fits with other research suggesting fish troubles in a lower-pH ocean, says Simpson. Studies have suggested reduced growth, and unfortunately, changes in formation of fish ear bones, or otoliths. So Nemo may have trouble hearing his new home as well as smelling it.
    Last edited by sirAdrian; 03-02-2009 at 18:07. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  10. Back To Top | #10
    Early whales gave birth on land

    Fossil finds help fill in gaps in the land-to-water transition

    It took early whales a while to fully break free of the land: For at least one species, females came back to shore to give birth, a new study suggests.
    Newly described fossils of ancient whales, which include the unprecedented discovery of a pregnant female, were unearthed in the hinterlands of central Pakistan in 2000 and 2004. The findings are providing scientists with new clues about the life, times and even the possible social structure of these enigmatic creatures.
    The discoveries “are rather spectacular, to say the least,” says Erich Fitzgerald, a vertebrate paleontologist at the Smithsonian Institution in Washington, D.C. “They’re quite incredible.”
    The family tree of today’s cetaceans — the varied group of aquatic mammals that includes whales, dolphins and porpoises — probably sprouted in southern Asia around 55 million years ago, as land-dwelling creatures began their march back to the sea. In that region, paleontologists have discovered many semiaquatic protowhales deemed to be charter members in cetacean diversification, including wolf-sized creatures that delved into streams about 50 million years ago (SN: 9/22/01, p. 180) and small fox-sized mammals that lived about 48 million years ago (SN: 1/5/08, p. 5). Many such creatures, some of them apparently evolutionary dead ends, appeared in southern Asia during this era. By 30 million years ago, the modern groups of toothed and baleen whales had evolved (SN: 5/14/05, p. 314).
    Now, Philip Gingerich, a paleontologist at the University of Michigan in Ann Arbor, and his colleagues add a new twig to the cetacean family tree, a 2.6-meter-long, mostly aquatic mammal that lived along the coast of southern Asia about 47.5 million years ago. Fossils of the species are described online February 3 in PLoS ONE. The researchers dubbed the creature Maiacetus inuusMaiacetus means “mother whale” in Greek, and Inuus was a Roman fertility god — in part because one of the fossils includes what the researchers say is a near-term fetus, a first for ancient whales.
    Those tiny remains, which include the skull, measure about 33 centimeters long and lie within the remains of the larger animal, says Gingerich. A lack of damage to the skull and other bones support the idea that the fossils are those of a fetus and not of a small, unrelated creature that had been eaten by the ancient whale, he notes. Many of the bones were only partially ossified, another clue that the tiny remains are those of a fetus.
    Position and orientation of the fetus within the mother provide important clues about the species, the researchers contend. The head is located near the opening to the birth canal, a sign that the whale would have been born headfirst. That, in turn, is a sign that the species came on land to deliver their young: While all large land mammals are typically delivered headfirst, so they can breathe during their birth, all modern cetaceans are born tail first to ensure they don’t drown during delivery.
    “This is really exciting stuff,” says Mark D. Uhen, a paleontologist at the Alabama Museum of Natural History at the University of Alabama in Tuscaloosa. Fossilization of a pregnant female “is a very rare event, but a very nice one.”
    Because the fetus’s first molars are well-mineralized, Gingerich and his colleagues suggest that Maiacetus young were precocial, or able to supplement their mother’s milk with other food sources soon after birth, as are all of today’s marine mammals.
    “From what we understand of cetacean evolution, you could predict that a fossil like this would be found,” says Fitzgerald. “I’ve been trying to convince myself that there’s a problem with it, but the evidence is there.” These fossils are the remains of a pregnant female, he adds.
    Another fossil of Maiacetus, recovered about a kilometer away from the specimen that includes fetal remains, is the most complete fossil yet found of an ancient whale, says Gingerich. Only a few vertebrae from the tip of the creature’s tail and a few bones from the ends of the digits are missing, he notes. Analyses suggest the animal’s feet were webbed.
    Several aspects of this particular specimen, including its pelvic structure, suggest that the creature was male. For one thing, most of its bones are about 12 percent longer than those of the female Maiacetus. Also, the canine teeth of the fossil are about 20 percent longer than the female’s, a common trait of males in species that display sexual dimorphism, in which the sexes differ in size or appearance.
    The features of this near-complete fossil, especially those of the tail, indicate that Maiacetus didn’t have a fluked tail like modern cetaceans, says Uhen. So, the creature probably dog-paddled its way through the water.
    Maiacetus is “a fantastic example of an early whale with aquatic specializations,” an “early experiment” in evolution that isn’t survived by any known descendants, Fitzgerald notes. The newly described species is quite different from living whales and dolphins, but also quite different from other ancestral species in the cetacean lineage, he says.
    The new fossils are very important, Fitzgerald continues, because those of many previously described species of protowhales include only one creature and are often very fragmentary. “It’s quite rare to have remains of adults as well as young,” he notes.
    In modern semiaquatic mammals such as seals and their relatives, species in which males are more than 16 percent larger than females have a harem-style mating system. During breeding season one male controls a territory and mates with several females. Since Maiacetus doesn’t show such a difference, it probably had a one-to-one, or dispersed, mating structure, Gingerich and his colleagues argue. The environment in which Maiacetus lived — along coasts with plenty of breeding room and plenty of food offshore — bolsters the notion that populations could spread out rather than compete for space and resources.
    The evidence described by Gingerich and his team “is consistent with sexual dimorphism, but not 100 percent conclusive,” Fitzgerald suggests. For one thing, most pelvic bones of this female Maiacetus aren’t preserved, so it’s difficult to ensure that the two adult specimens are indeed of different sexes. However, he notes, “I think they’ve gone about as far as they can go with the evidence that’s available.”
    Although it’s possible that the presumed male and the female are different sizes because they’re different ages or members of two closely related species, it’s probable that they’re the same species, Uhen says. “Sometimes you can only go with the evidence that you’ve got.”
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  11. Back To Top | #11
    Animal ancestors may have survived ‘snowball Earth’

    Chemical fossils push back the date for animal life to at least 635 million years ago

    A new analysis of ancient chemical fossils has rocked the cradle of early animal evolution, bumping back compelling evidence of animal life to at least 635 million years ago.
    The findings, published in the Feb. 5 Nature, suggest that the ancient ancestor of fully formed animals survived a massive glaciation that enshrouded the Earth in ice at the end of the aptly named Cryogenian period. Debate continues over how much of the planet was frozen during two ice ages, each possibly a “snowball Earth” event that flanked this period, which extended from about 790 million to 630 million years ago.
    The new results suggest that even if glaciers reached the equator during the second ice age, it is likely that warm pockets, perhaps created by volcanic activity or hydrothermal vents, may have persisted and harbored life.
    “Evidence of animal life from before the Marinoan,” the severe glaciation of 635 million years ago, “is really something,” says Jochen Brocks of the Australian National University in Canberra. Brocks and Nicholas Butterfield of the University of Cambridge in England coauthored a Nature commentary on the new work.
    There’s evidence of eukaryotic life — organisms with DNA sequestered in a protective nucleus — from roughly 1.9 billion years ago, says Brocks. But proper multicellular animals don’t appear on the scene until much later. The Cambrian explosion is often cited as the inaugural ball of animal evolution, a period of roughly 20 million years that began about 520 million years ago when representatives of many of today’s major animal groups became established.
    But there’s a fair amount of evidence that animals evolved before the Cambrian, including a bizarre assemblage known as the Ediacaran fauna, which flourished during the Ediacaran period that some studies suggest lasted from about 635 million to 542 million years ago. Many scientists believe the multicellular animals of Ediacaran were an early experiment in animal evolution that ended badly and had few survivors.
    Sponges, however, may have come on the scene before the Ediacaran period and lived through it. The new analysis, led by organic geochemist Gordon Love of the University of California, Riverside, documents the molecular remains of a steroid from sedimentary rock deposited 150 meters below the end of the Marinoan ice age. (Researchers debate when this ice age actually started.)
    The steroid fossil, known as 24-isopropylcholestane, or 24-ipc, is the geologically stable form of a steroid known today from the cellular membranes of one of the three classes of sponges, the Demospongiae. A small group of algae also make the molecule, but the ratios of 24-ipc to other algal compounds rules algae out as a source.
    Working with cores from a salt basin in south Oman, Love and his team document the presence of 24-ipc throughout the Ediacaran and in the layers beneath. To ensure that this chemical fingerprint hadn’t migrated from younger rocks, the researchers also analyzed the signal from the tough matrix of organic matter known as kerogen that can’t move through rock.
    The findings can’t say when multicellular animals first appeared but can say that multicellular animals had to be around by at least 635 million years ago and, the researchers report, maybe as early as 751 million years ago.
    “These are the oldest bona fide animal fossils,“ says molecular paleobiologist Kevin Peterson of Dartmouth College. Putative fossil embryos that date to around 580 million years ago were previously the oldest unequivocal fossils considered ancestors of today’s animals.
    “Finding a molecule that was made by an organism, that means the biosynthetic ability to make that molecule must have evolved earlier,” Brocks says.
    The Cryogenian period is marked by an early glaciation — the Sturtian — then a period of warming, and then a second glaciation, the Marinoan. The fossil molecules suggest that the animals that made them had to be around by the end of the Marinoan, and they may have evolved in the warming period between the Sturtian and Marinoan, Love says.
    Even if the glaciations during this snowball Earth period didn’t freeze the seas, as some have suggested, they would have forever altered ocean chemistry, says Love. The environmental upheaval could have opened new niches and presented an opportunity for multicellular sponges to spread throughout the seas.
    The new work fits nicely with molecular clock work dating the evolution of multicellular life, says Peterson. It also ties in well with ideas about ocean and atmospheric chemistry. These early sponges might have helped bring about the oxygenation of the deep oceans, which then paved the way for more life. Sponges are a dominant stationary animal in the Cambrian, but then their presence seems to taper off, perhaps because of the rise of other animals.
    “Sponges are essentially vacuum cleaners; they suck the organic matter out of the world’s oceans,” Peterson says. Amounts of organic matter, the organic form of carbon, are linked to a complex cycle that includes oxygen.
    Brock agrees. “Sponges might have filtered all the crap away, might have been the cleaner of the oceans,” he says. “It’s an interesting idea. In total this is a very nice finding, rigorous work and a good job.”
    Editare ulterioară
    Caterpillar noise tricks ants into service

    Worker ants know a royal command, whatever the source

    That regal tone works even on ants.
    A kind of European caterpillar can garner royal treatment from ants by mimicking the ch-ch-ch-ch of their queen, says an international research team.
    Ants of the species Myrmica schencki can be fooled into carrying certain caterpillars into the colony nurseries where the fakers enjoy full care and five-star dining, explains Jeremy Thomas of the University of Oxford in England. An interloper caterpillar gains most of its body mass while luxuriating in ant care, and then turns into a Maculinea rebeli butterfly.
    Chemical camouflage alone will let the caterpillars game their way into the ant colony. Now experiments show that the noises the caterpillars make get them the premium treatment, Thomas says. The rhythmic caterpillar purring has the effect of the queen ant’s noises, not those of a worker, Thomas and his colleagues report in the Feb. 6 Science.
    It’s news that a queen sounds different from workers in an ant colony, Thomas says. Ants have such remarkable chemical messaging systems that their noises haven’t received much scientific attention.
    “I haven’t been this excited about a paper in a long time,” says tropical butterfly ecologist Phil DeVries of the University of New Orleans. He made the first recordings of caterpillar noises, which he says occur only in groups that have some kind of relationship with ants.
    M. rebeli caterpillars make a mini version of the brrrrrr of a woodcock or snipe, Thomas says. Recent work has suggested that caterpillar noises may come from repeated muscle spasms. And when caterpillars become enclosed pupae, they make noises by rubbing a scraper, or plectrum, on their abdomen against a patch of fine grooves called a file. “Actually they can wriggle their abdomen quite a bit,” Thomas says.
    Adults of four of the 11 ant subfamilies also make noises by rubbing plectrum and file, Thomas says. “It’s rather like strumming a guitar.” In a quiet room of ants, he can just manage to hear “quite a scratchy sound,” he says.
    Advances in miniature electronics made the new study possible. Specially built ant-scale microphones and speakers allowed researchers to record both queen and worker ants under normal conditions and then play back the noises and observe ant behavior.
    To a human ear, queens and caterpillars don’t sound at all similar, Thomas warns. Yet ants perceive noises differently, picking up vibrations with sensors in the legs. “There is a debate about how well, if at all, they perceive airborne sounds,” he says.
    When he and his colleagues played the caterpillar recordings to an ant colony, workers reacted as they do to queen scratchings. Most distinctive was what Thomas describes as on-guard attendance. Clustering around the speaker, worker ants stay motionless in a hunched-over posture with antennae out and jaws slightly open. Like an honor guard around a human queen, worker ants will maintain that pose for hours.
    Queen-mimicry could explain the VIP treatment caterpillars receive in the ant colony. “Quite often they’re treated as superior beings,” Thomas says. In a crisis, worker ants rescue caterpillars before a regular ant brood. And in famine, workers will kill their own brood and feed it to the caterpillar.
    The “voice” works.
    Last edited by sirAdrian; 06-02-2009 at 13:30. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  12. Back To Top | #12
    Women have hormonal cues for baby cuteness

    Premenopausal women, especially those taking oral contraceptives, have an advantage in picking out the cutest babies

    Everyone oohs and ahs over babies. Ironically, new research suggests that young women taking oral contraceptives are especially good at picking out babies with the most adorable little mugs.
    Female sex hormones sensitize women to differences in babies’ cuteness, propose psychologist Reiner Sprengelmeyer of the University of St. Andrews in Scotland and his colleagues. When given choices between computer-manipulated images of a baby’s face, premenopausal women discern gradations in the cuteness of the face better than either postmenopausal women or men of all ages, Sprengelmeyer’s group reports in the February Psychological Science.
    In the new study, young women taking hormone-boosting contraceptive pills outdid those not taking contraceptives, as well as premenopausal women in general, at detecting babies’ cuteness.
    Women of all ages identified subtle size differences between pairs of squares with comparable skill, indicating that hormone levels had no effects on basic visual faculties, the researchers assert. Instead, relatively high reproductive hormone levels in premenopausal women make them more emotionally responsive to cute babies, the team suggests.
    “Cuteness is one of the factors that determine how strongly a mother interacts with her infant,” Sprengelmeyer says. A 1995 investigation found that mothers of babies independently rated as more attractive were particularly affectionate and playful with their children, whereas mothers of less-attractive babies provided routine care without much overt affection.
    A hormone-linked sensitivity to facial cuteness may prompt mothers to bond emotionally with their babies, Sprengelmeyer speculates.
    “It’s tough to know what to make of these findings without knowing the ways in which cute babies differ from uncute babies,” remarks psychologist Steven Gangestad of the University of New Mexico in Albuquerque. It’s not known whether a cute face signals a baby’s physical vigor or other advantageous characteristics to a mother, Gangestad notes, or whether mothers who invest special effort in raising cute babies reap big dividends later.
    Sprengelmeyer’s team asked independent raters to classify a series of babies’ faces on a 7-point scale. Then the researchers picked 40 faces, half boys and half girls, that the independent raters had agreed were cute or less cute. Using a computer program that incorporated data from 174 facial landmarks, the team defined the average shape of cute and less cute faces. Those average faces provided baseline data so the researchers could create faces with varying cuteness from five new male and five new female babies’ faces.
    Adult volunteers viewed pairs of faces of the same baby and tried to identify the cuter face. On some trials, faces differed greatly in cuteness. On others, cuteness differed slightly.
    An initial experiment included 24 young women and 24 young men, ages 19 to 26, as well as 24 older women and 11 older men, ages 45 to 60. A second experiment consisted of 10 premenopausal and 10 postmenopausal women, none of whom took hormone replacement therapy or had undergone a hysterectomy. A final experiment involved 24 young women, half of whom took oral contraceptives.
    Sprengelmeyer’s group plans to examine whether sensitivity to babies’ cuteness rises and falls in concert with changing progesterone and estrogen levels during women’s menstrual cycles.
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  13. Back To Top | #13
    Access : French electionIs French science in decline... : Nature


    [ame=""]YouTube - Sarkozy and the french Research[/ame]
    Aici e varianta in engleza. (tot discursul il gasiti pe pagina presedintelui Frantei in franceza evident, si care e mult mai lung). Asta e varianta scurtata la 5 minute, si un pic umoristica a discursului.
    Traducerea sufera un pic pe alocuri (cei care stiu franceza ar face mai bine sa asculte varianta in franceza, si sa ignore traducerea)

    Sa-l vad pe Extra3OO si ai lui colegi capitalisti cum vin sa-mi explice mie cat de mult apreciaza el sistemul.

    Daca-l prind pe Sarkozy pe strada, ii rup picioarele.
    Last edited by Lord Raptor; 10-02-2009 at 16:40.
    Americans have no capacity for abstract thought, and make bad coffee.

  14. Back To Top | #14
    Postpartum psychosis most likely in month after childbirth

    Problem plagues about one in 1,000. Study of first-time mothers suggests reduction in hormone levels could be a trigger

    Mothers with no previous history of mental illness face the greatest risk for postpartum psychosis during the first month after childbirth, a new study suggests.
    Postpartum depression is a common problem for many women in the days following delivery. But about one in 1,000 new mothers develops postpartum psychosis, a serious mental illness involving delusional thoughts, hallucinations and the inability to distinguish between reality and imagination.
    The new study found that first-time mothers who suffer postpartum psychosis faced the highest risk in the first month after delivery, and that the problem can strike women who had no previous history of mental illness.
    In the study, published online February 9 in PLoS Medicine, epidemiologist Unnur Valdimarsdóttir of the Karolinska Institute in Stockholm and colleagues used hospital records to track first-time mothers during the 90 days following childbirth. Of the almost 750,000 women in the study, 892 developed postpartum psychosis, with most cases reported within a month of childbirth. The rapid reduction in hormone levels after childbirth could trigger the psychosis in some women, the authors suggest.
    Earlier studies show that schizophrenic women face the greatest risk of psychosis when hormone levels are low. Trauma associated with the pregnancy and birth itself could also contribute to postpartum psychosis, Valdimarsdóttir says.
    The study found that about half of the women who developed postpartum psychosis had no previous history of hospitalization for mental illness. “Postpartum psychosis could be the only psychotic episode a woman ever experiences,” says Valdimarsdóttir. “But for a significant number of women, childbirth can set off a recurring psychotic disorder.”
    Genetics can also play a role. “Perhaps the hormonal fluctuations trigger psychosis in women who already have a genetic predisposition for developing mental illness,” comments Donna Stewart, a psychiatrist at the University of Toronto. “Even women who had never been hospitalized for mental illness could have received outpatient care, or had a family history of psychiatric problems.”
    The researchers found that the risk of developing psychosis increased for mothers over the age of 35. “This could be because older first-time mothers are more likely to have a problematic pregnancy,” Valdimarsdóttir says. Other factors, such as higher infant birth weight and maternal diabetes, lessened the risk. Mothers with diabetes tend to have larger babies, says Valdimardóttir, but why maternal diabetes would lessen the risk of postpartum psychosis is not known. “Perhaps it’s because these mothers are more closely monitored throughout their pregnancy,” Valdimarsdóttir suggests.
    Editare ulterioară
    Winter birds shift north
    New Audubon report suggests climate change is the culprit

    North could be the new south for wintering birds.
    More than half of 305 widespread bird species across North America are spending their winters farther north than they did 40 years ago, says a report released February 10 by the National Audubon Society.
    Those shifts dovetail with warming trends in winter temperatures recorded by state during that time, says Audubon scientist Greg Butcher, coauthor of the report. Overall the wintering grounds of the birds have shifted an average of 56 kilometers (35 miles) north in cold months during the past four decades.
    Some have moved much more, including red-breasted mergansers (510 kilometers or 317 miles) and purple finches (504 kilometers or 313 miles).
    Details of the movement pattern, such as greater shifts in places having more marked temperature changes, suggest climate change is driving the shifts, Butcher says. “We’re showing that global warming isn’t something that’s going to happen far away, say in the Arctic and Antarctic, and it’s not something that might happen in the future,” he says. “It’s something that’s already happened and has been occurring over the last 40 years.”
    Woodland birds in the study moved the most, averaging more than a 113-kilometer (70-mile) northward shift in range, more than twice the average change in any other bird group in the study. Not all the species went north. For example, nine of the grassland species moved south, a change that may be attributed to factors beyond temperature.
    Butcher and his colleagues drew on data from the Christmas Bird Counts, a 109-year-old tradition in which birders brave whatever winter throws at them to visit predetermined sites where they record all the species they can find during a 24-hour period. In recent years, more than 50,000 volunteers have turned out for the count at some 2,000 locations across the continent.
    Such citizen science efforts offer a way to grasp broad trends, says conservation biologist Stuart Butchart of BirdLife International, headquartered in Cambridge, England.
    “The strength of this study is that it’s looking at a broad range of species across a large geographic area,” he says. “It’s the overall pattern that’s important and should be raising alarm bells.”
    Species that have large ranges may be a good indicator but may not be the birds most at risk from climate change, Butcher says. Species with small, specialized ranges may not have anywhere safe to go. “We’re terribly worried about Hawaiian forest birds,” he says. Warming temperatures allow mosquitoes to rise higher up mountain slopes, carrying avian malaria that has devastated lowland populations.
    And even though birds offer a good source of data, other kinds of creatures with even less mobility may be more affected. “Start with trees,” Butcher says. “Trees are big sedentary organisms.” There could be plenty more impacts that don’t get counted every Christmas.
    Last edited by sirAdrian; 11-02-2009 at 11:48. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  15. Back To Top | #15
    Registered User
    Join Date
    Jul 2007
    Matrix Style: "IBM Patents Bionic Armor That Gives Humans Ability To Dodge Bullets"
    Bionic Body Armor: IBM Patents Bionic Armor That Gives Humans Ability To Dodge Bullets

  16. Back To Top | #16
    Obama's budget would boost science

    In his not-exactly-State-of-the-Union address to Congress Tuesday night, the President Obama promised that his administration would boost support for science. This morning, we got an inkling of what he was referring to. The official “outline” of the first Obama budget was released at 11 a.m. And this broad-brush blueprint asks Congress to fatten the National Science Foundation, for example, with an extra $7 billion — a hefty 16 percent increase over last year’s funding.
    The new budget document argues that “investments in science and technology foster economic growth, create millions of high-tech, high-wage jobs that allow American workers to lead the global economy” and more. For that reason, the budget document says, the president’s proposed budget for fiscal year 2010 is aimed at beginning to move toward a doubling of federal funding for basic research over the next 10 years. The actual increase in the coming year would be $950 million, it says.
    The Energy Department would see lots of boosts. Most of the dollar figures mentioned in today’s budget document reflect money already targeted to be spent from the stimulus. This includes $3.4 billion for low-carbon coal technologies, including the carbon sequestration. But in addition to the $1.6 billion in the recently passed economic stimulus package for basic energy research at DOE, the new budget would provide “substantially increased support for the [DOE] Office of Science.” What does that mean? We’ll have to wait a month or so for the actual line-item budget blueprint to see. But we already know that Energy Secretary Steven Chu has been a big booster for this, something he views as his agency’s crown jewel.
    Words you wouldn’t have seen in George W. Bush’s budget documents: statements like the president’s intention to make “climate change research and education a priority.” Yep, that’s what it says in today’s document. Toward that end, there’s not only money in the NSF budget for climate science, but also the call for spending $1.3 billion for development and lofting of “vital weather satellites and climate sensors.” (I guess some of that will have to go toward replacing the carbon-monitoring satellite that crashed shortly after takeoff a couple days ago.)
    There is a curious and fairly long section of text under the Environmental Protection Agency heading that describes plans to begin “a comprehensive approach to transform our energy supply and slow global warming.” Global warming has never been a big EPA issue. Most efforts to limit our carbon footprint are managed through programs at Commerce and Energy. But in today’s outline, the administration describes its hope to jump-start an ambitious cap-and-trade program for greenhouse-gas emissions. This program would look to cut greenhouse emissions 14 percent below 2005 levels by 2020 and approximately 83 percent below 2005 levels by 2050. Talks of cap-and-trade proposals have been floating around for years. It looks like this president is committed to finally making something happen.
    In his Tuesday night address, the president hinted at big boosts for biomedical research. Today’s outline calls for investing more than $6 billion in research at the National Institutes of Health “as part of the administration’s multi-year commitment to double cancer research funding.” Today’s budget outline explains that this influx of funds would “build upon the unprecedented $10 billion” for NIH research in the economic stimulus.
    The president’s new budget also advocates expanding research that compares the effectiveness of competing medical treatments — something you can read more about in the upcoming March 14 print Science News, set to be available online Friday.
    The EPA would get a boost in funding, but largely for infrastructure improvements and things like a new Great Lakes restoration program.
    The National Institute of Standards and Technology (once called the National Bureau of Standards) is a small but important Commerce Department agency charged with making sure new “yardsticks” exist for helping develop new technologies — ones that will keep the nation competitive with other economic powerhouses. In recent years, NIST has been marginalized, with large sections of it targeted for elimination (but usually rescued by Congress, sometimes at the 11th hour). In a turnabout, the Obama administration acknowledges that NIST’s health is important to the nation’s technology infrastructure — infrastructure being a priority in the stimulus. Under the president’s budget plan, NIST would get money to keep important programs alive and would be designated the headquarters for administering $4.7 billion in stimulus money “to expand broadband deployment, adoption, and data collection.”
    Something you don’t see in today’s budget outline is any mention of beefing up research programs at the Department of Agriculture. USDA’s research service has been hurting in recent years. And a failure to boast about turning that around suggests that the president won’t be trying to turn that around — at least not in the coming year.
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  17. Back To Top | #17
    Modern feet step back 1.5 million years

    Footprints preserved at an African site suggest that the feet of a 1.5 million-year-old human ancestor looked much like those of people today
    Human ancestors created some remarkably lasting impressions on the eastern African landscape around 1.5 million years ago. Walking across a muddy patch of terrain near what’s now Ileret, Kenya, these ancient individuals left footprints that hardened and have now been excavated by a team of scientists.
    On close inspection, the preserved footprints provide the oldest evidence for a virtually modern-human foot and walking style in a human ancestor, report geologist Matthew Bennett of Bournemouth University in Poole, England, and his colleagues in the Feb. 27 Science. Finding what amounts to the fossilized behavior of these creatures provides new clues to the evolution of upright stance and walking in modern humans.
    Bennett’s team identifies the ancestor as an early Africa-based Homo erectus, or Homo ergaster as some scientists call it.
    Measures of the size, spacing and depth of the Ileret impressions allowed the researchers to estimate individuals’ heights, weights and stride lengths, all of which fell within the range of modern humans. Digitized images of the newly discovered footprints show a big toe in line with the other toes, an arrangement that contrasts with the angled, grasping big toes of apes. Other humanlike features of the prints include a pronounced arch and short toes.
    Ancient foot impressions at Ileret complement earlier fossil leg and pelvis finds in Africa indicating that, by about 2 million years ago, early H. erectus displayed much the same body size and proportions as modern humans, the researchers say.
    “The Ileret footprints add to evidence that early Homo erectus had a body adapted to traveling long distances, at a time when food sources were patchily distributed across the landscape,” says anthropologist and excavation director John Harris of Rutgers University in New Brunswick, N.J.
    Harvard University anthropologist Daniel Lieberman says the African footprints support his 2004 proposal that around 2 million years ago the Homo genus evolved bodies capable of running long distances. Springlike arches and short toes observed on the Ileret footprints would have enabled endurance running, Lieberman remarks.
    “How could H. erectus have hunted more than a million years before the invention of tipped spears, as we know it did, without the ability to run well?” he asks.
    That’s a plausible hypothesis, comments anthropologist Susan Antón of New York University, but she says the Ileret footprints might instead come from either of two other species in the human evolutionary family, Homo habilis or Paranthropus boisei. Scientists know little about the size variation in H. erectus (SN: 12/6/08, p. 14) and the other two species. Some individuals in any of these species may have had feet as big as those that made the Ileret impressions, Antón says.
    Other footprints from members of the human evolutionary family, dating to 3.5 million years ago, were discovered by Mary Leakey between 1977 and 1979 at Laetoli, Tanzania. Researchers disagree about whether these finds — often attributed to Australopithecus afarensis, a fossil species that includes the partial skeleton of Lucy — reflect an apelike or humanlike foot anatomy.
    Bennett’s team argues that the Laetoli prints, which are smaller than those at Ileret, show signs of an upright gait combined with a shallower arch and more angled big toe than seen at Ileret.
    Anthropologist Bernard Wood of George Washington University in Washington, D.C., agrees. The Ileret footprints underscore skeletal evidence for a radical shift in anatomy that occurred sometime between the demise of A. afarensis around 3 million years ago and the appearance of H. erectus nearly 1 million years later, Wood holds.
    The Ileret finds are “a treasure” that strongly supports a modern-humanlike stance by 1.5 million years ago, says anthropologist Russell Tuttle of the University of Chicago. But the nature of the Laetoli individuals’ feet and gait, as well as their evolutionary identity, remains unresolved, in Tuttle’s view.
    Digitized analyses of the Laetoli footprints have not been conducted, he notes. Weathering of the Tanzanian impressions after excavation, followed by reburial of the finds because of ground movement and vegetation growth, will obstruct further study, adds Tuttle, who studied the Laetoli footprints shortly after their discovery.
    Scientific prospects appear brighter at Ileret. From 2005 to 2008, excavations there revealed footprints in two sediment layers, one about five meters above the other. Earlier research had dated both layers to about 1.5 million years ago, separated by 10,000 to 20,000 years.
    Three footprint trails appear on the upper sediment layer — two trails of two prints each and one of seven prints. Another six isolated prints dot the surface. On the lower layer, the researchers found one trail of two prints and a single, relatively small print that was probably made by a young individual. A variety of four-legged animals also left footprints on this layer.
    “I have no doubt that we’ll find more footprints at this site,” Harris says.
    Editare ulterioară
    Playing for real in a virtual world

    Gender still influences how preteen boys and girls play when they assume new identities online

    In a virtual setting where fifth-graders become wizards and athletes, and even change sexes, preteens stay true to their real-world selves. Classic sex differences in play preferences, characterized by rough-and-tumble games among boys and intimate conversations among girls, still exist after youngsters adopt a range of personas for virtual encounters, investigators find.
    Boys who create girl avatars — or computerized altar egos — and girls who create boy avatars still behave consistently with their biological sex, say psychologist Sandra Calvert of Georgetown University in Washington, D.C., and her colleagues.
    In their new study, published online February 20 in the Journal of Applied Developmental Psychology, about 13 percent of fifth-graders chose opposite-sex avatars, a practice the researchers call gender-bending. Pairs of kids — all of whom knew each other — experimented more with avatar identities than pairs of unfamiliar children did in a similar, 2003 study led by Calvert. Same-sex pairs showed this pattern most strongly.
    As fifth-graders learned to construct avatars and use these characters to interact with others in a multi-user domain, or MUD, experimentation with avatar costumes, sexes and names increased sharply. But as in real-world play, MUD play centered on self-exploration rather than self-alteration, Calvert asserts.
    Boys and girls who knew each other often had difficulty playing together as avatars, she adds. Many boys wanted to play action-oriented games, while girls pressed for written conversations. That pattern reflects preteens’ preferences for playing in same-sex groups.
    “MUDs can provide a virtual play space for preadolescent children to discover who they are, as well as a 21st century place to interact with friends,” she says.
    Boys and girls in all cultures tend to differ in their play styles, remarks psychologist David Bjorklund of Florida Atlantic University in Boca Raton. “What’s impressive is that these behavioral styles extend to the virtual world,” he says.
    Infrequent gender-bending observed in the new study supports the idea that young people typically view online worlds, from MUDS to blogs, as places to deal with real-life concerns, comments psychologist Kaveri Subrahmanyam of California State University, Los Angeles.
    “People don’t go online to leave their bodies behind and find new selves, but instead seem to be taking their offline selves, including their biological selves, with them,” she says.
    Calvert’s team studied 126 fifth-graders, most ages 10 and 11, randomly selected from five schools and a boys and girls club in the Washington, D.C., area. Participants included 61 boys and 65 girls. Pairs of children who knew each other entered a room where they used laptop computers to play in a MUD.
    Each child first chose a name, a sex and a costume — wizard, firefighter, soccer player, regular kid in a T-shirt and jeans or punk kid in a leather jacket — for his or her avatar. Pairs then interacted using avatars for two 10-minute sessions, separated by a brief rest period.
    Children used a computer mouse to move their avatars, alter avatars’ facial expressions and body postures and switch among six background scenes. Kids typed messages to each other that appeared in speech bubbles above avatars’ heads.
    In her 2003 study of 84 preteens who didn’t know one another, Calvert found that only two boys created girl avatars and no girls chose boy avatars. In the new study, 21 girls and 11 boys engaged in gender-bending.
    Last edited by sirAdrian; 03-03-2009 at 11:19. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  18. Back To Top | #18
    Gene links autism, bellyaches

    Whether dietary changes can improve brain functioning is still unclear

    Parents often report that tummy troubles and autism go hand in hand. Some have even suggested that special diets can reduce autism symptoms. But many experts have dismissed the connection as mere coincidence or have attributed the overlapping conditions to different genetic or environmental factors.
    Now new research, published in the March Pediatrics, shows that there is a genetic link between autism and gastrointestinal disorders. It’s unclear whether this genetic link means that an environmental therapy such as diet could boost brain function or if just feeling better could be responsible for improved behavior.
    Researchers from Vanderbilt University had previously linked a genetic variant in the control panel of the MET gene to autism. In the general population, some people have the DNA letter G in a particular position in the control panel, which determines whether the MET gene is active. Other people have a C in that position. That variant of the gene, known as the MET C allele, turns down production of MET, a protein involved in brain development, gut repair and other body functions. Children who inherit copies of MET C from both parents have more than twice the risk of developing autism as children who get the G variety from both parents.
    In the new study, the Vanderbilt team and additional colleagues found that children with autism who have two copies of MET C are also more likely to have gastrointestinal problems than people who have two copies of the G variant or a combination of G and C. The study is the first to demonstrate a possible genetic cause for the co-occurrence of autism and digestive tract problems.
    Some people sampled in the study also have a double dose of the MET C allele but have neither autism nor reported gastrointestinal problems. There are also children with two C versions who have autism but not stomach problems.
    Identifying such variants will help doctors subdivide autism into different categories and aid in tailoring treatments for the disorder, says Daniel Campbell, a geneticist at Vanderbilt School of Medicine in Nashville, Tenn., who led the study. But finding a common cause for the two conditions doesn’t mean that autism is caused by stomach problems, he says. And changing the diet of a child with autism may improve their mood and behavior, but won’t alter the underlying brain problems that cause autism.
    “The change in diet is not changing brain structure, it’s just making the kid feel less sick,” he says.
    Martha Herbert, a pediatric neurologist at Massachusetts General Hospital’s Center for Morphometric Analysis in Charlestown, and Harvard University Medical School applauds the discovery. “What they’ve shown is that [autism and gastrointestinal disorders] are co-occurring,” Herbert says. “That’s a very welcome development, and these people should be commended for recognizing that autism doesn’t just affect the brain, it affects the whole person.”
    Herbert says though she is in the minority, she thinks that autism may result not from subtle differences in brain structure but from bodywide dysfunction in cells. The MET gene may be one example; when the gene’s activity is disrupted, multiple body functions go wrong, including brain activity and digestive system function. Treatments that alter MET’s activity or affect a network of which MET is a part may improve both bellyaches and autism symptoms, she says.
    Editare ulterioară
    Out-of-sync days throw heart and metabolism out of whack

    Study shows sleep/wake cycle is more important than number of hours slept

    Sleeping during the day and staying awake at night can lead to heart and metabolic problems, even after just a few days of the out-of-sync schedule, a new study reports. The results, published online March 2 in Proceedings of the National Academy of Sciences, may help explain the high rates of heart disease, diabetes and obesity among people who work the graveyard shift.
    “The problems of shift work affect so many people, but there are very few studies that address the underlying mechanisms,” comments Eve Van Cauter, a sleep researcher at the University of Chicago. “This is what [the researchers] have done, and elegantly so.”
    Based on Bureau of Labor Statistics data, the researchers estimate that 8.6 million people in the United States are shift workers.

    To figure out what happens when people are moved from their normal sleep/wake cycle, Frank Scheer of Brigham and Women’s Hospital in Boston and his colleagues imposed a 28-hour day on study participants. “The biological clock ticks along at its own rate,” Scheer says, and that rate, not so coincidentally, is right around 24 hours for most people.
    Some people can adjust to day periods that are slightly longer or shorter than 24 hours and, with the right light cues, can also adjust to a shifted 24-hour sleep/wake cycle. But studies have shown that people cannot acclimate to a 28-hour cycle.
    For this study, five men and five women lived out 28-hour cycles in dimly lit, private rooms with no windows to clue the volunteers in to the real time. Over the course of the 10-day experiment, the total amount of shut-eye did not vary: Participants slept nine hours and 20 minutes each 28-hour day (instead of eight hours every 24-hour day). But the times of sleep varied. Each “day,” volunteers went to bed four hours later, in real-world time, than they had the previous “day.”
    When the volunteers were awake and active in the middle of the night — when their bedtime had shifted by 12 hours — researchers noted a significant spike in blood pressure, a decrease in the appetite-regulating hormone leptin and higher–than-normal blood sugar levels. Three of the 10 subjects, who were all previously healthy, had blood sugar that reached prediabetic levels.
    “Even after just a few days, they showed striking changes in glucose metabolism,” Scheer says. "The rapid onset within just a few days shows that this may even temporarily affect the millions of people experiencing jet lag every year."
    Because the total amount of sleep time did not change, researchers concluded that these harmful effects stem from an off-kilter sleep cycle, and not from simply too little sleep.
    “This experiment demonstrates that misalignment in and of itself is critical,” comments Charles Czeisler, a sleep expert at Harvard Medical School.
    The new research didn’t measure the quality of sleep, which may be responsible for some of the harmful effects of shift work, Van Cauter says. “Shallow, fragmented sleep could be the mediator.”
    Last edited by sirAdrian; 03-03-2009 at 11:21. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  19. Back To Top | #19
    Autism immerses 2-year-olds in a synchronized world

    Toddlers with autism may closely monitor co-occurring sights and sounds, resulting in a neglect of social signals

    When 2-year-olds with autism look at someone’s face, they may crave synchronized detection rather than social connection. Toddlers with this developmental condition track sounds and sights that occur together, such as a mother’s lips moving in time with sounds coming out of her mouth, rather than social cues, such as the gleam in that same mother’s eyes, a new study suggests.
    Locked in a world of co-occurring sound and motion, youngsters with autism neglect social signals that critically contribute to mental and brain development, propose psychologist Ami Klin of Yale University’s Child Study Center and his colleagues.
    “Our findings lead us to the rather sad hypothesis that a toddler with autism might watch a face but not necessarily experience a person, since so much of that experience involves mutual eye gaze,” Klin says.
    The new study, published online March 29 in Nature, indicates that by age 2, kids with autism don’t notice the array of cues indicating that a body is moving. Non-autistic children do so within days of birth. Young animals in many species, from humans to birds, monitor signs of movement by others as cues to initiate social contact.
    While earlier studies have suggested that children with autism often don’t look at other people’s eyes, it’s been unclear why this behavior occurs. Few studies have included toddlers or infants with autism, who are difficult to diagnose.
    “For the first time, this study has pinpointed what grabs the attention of toddlers with autism spectrum disorders,” remarks psychiatrist Thomas Insel, director of the National Institute of Mental Health in Bethesda, Md.
    Klin’s study employed point-light cartoons created with data from actors playing five children’s games. Each animation, consisting only of bright dots positioned at body joints, played normally on one side of a computer screen. On the other side, it played upside-down and in reverse. Children with no developmental problems have difficulty discerning movement by inverted figures.
    A soundtrack of the actor’s voice and accompanying sound effects was played with each pair of cartoons.
    Eye-tracking devices determined that 39 typically developing toddlers and 16 toddlers with non-autistic developmental delays preferred to look at upright animations, tracking biological motion. In contrast, 21 toddlers with autism generally tended to look back and forth at upright and reversed animated figures, suggesting that these children paid no attention to the moving bodies.
    But toddlers with autism made an exception for a video with a cartoon that featured a game of patty-cake, where colliding dots that represented two hands repeatedly produced a clapping sound. This physical synchrony existed only for the upright figure because the inverted figure played in reverse so its motions didn’t match the soundtrack.
    A closer analysis of other synchronized sounds and motions in the five cartoons indicated that sensory pairings almost always drew the attention of toddlers with autism.
    It’s too early to say for sure whether autism really involves a focus on audio-visual synchronies, since a broader mental trait could explain Klin’s new findings, cautions psychologist and autism researcher Mark Strauss of the University of Pittsburgh. An intense focus on details may partly explain a tendency of kids with autism to ignore moving bodies while focusing on synchronized physical events (SN: 7/7/07, p. 4), Strauss suggests. Greater difficulty in detecting subtle eye movements versus larger mouth movements may also contribute to this pattern, he notes.
    Questions remain about the extent to which kids with autism make eye contact. Klin’s team reported last year that 2-year-olds with autism mainly look at people’s mouths. But in an upcoming study, Strauss’ group finds that 8- to 12-year-olds with autism look others in the eyes as much as their non-autistic peers.
    Klin's group now plans to see whether children with autism become more social after receiving training that directs attention away from synchronized sights and sounds and toward signs of biological motion.
    Editare ulterioară
    Parasites hinder immunity against cholera

    Intestinal hitchhikers may render people more vulnerable to the microbe and might lessen vaccines’ effectiveness

    Harboring intestinal parasites seems to limit a person’s ability to fend off cholera, a study conducted in Bangladesh shows. The finding might explain why vaccines against cholera have shown only spotty effectiveness and also suggests that vaccination campaigns should be preceded by programs to wipe out parasites, particularly intestinal worms. The study appears in the March PLoS Neglected Tropical Diseases.
    The bacterium Vibrio cholerae causes cholera and is spread in unsanitary food or drinking water. In the past, scientists had been puzzled when experimental cholera vaccines that induced a strong response in Western volunteers failed to generate consistent immunity when given to people in the tropics. Researchers initially suspected poor nutrition or genetic differences, says pediatrician Jason Harris of Harvard Medical School and Massachusetts General Hospital in Boston. But in recent years, some came to wonder whether other infections, including those caused by parasites that are prevalent in poor tropical countries, might be hindering the immune response and therefore a vaccine’s effect.
    Harris and his U.S. colleagues teamed with researchers at the International Centre for Diarrhoeal Disease Research in Dhaka to collect and analyze blood and feces samples from 361 people who were brought to hospitals with severe cholera from 2001 to 2006. The scientists found that 53 of the patients also had parasitic infections.
    Those with intestinal worms had markedly poorer antibody production against the toxin made by the cholera microbe than did those without worms, the researchers report. These responses against the actual microbe would suggest a similar effect in people getting vaccinated.
    The Vibrio cholerae toxin causes severe diarrhea when it comes into contact with the intestinal lining, and hospitalized cholera patients receive fluids to prevent life-threatening dehydration. People naturally develop antibodies against the toxin and against the microbe itself to the point that adults in endemic countries such as Bangladesh become largely immune to cholera after repeated exposures. Children initially exposed are most vulnerable.
    The precise mode of action by which intestinal worms lessen antibody production against the toxin is poorly understood, the researchers say.
    “Intestinal parasites do seem to have influences beyond their own little niche,” says Thomas Nutman, an immunologist at the National Institute of Allergy and Infectious Diseases in Bethesda, Md. “This is among a growing list of studies that have addressed the bystander effect — a spillover effect, if you will – of these [worm] parasites,” he says.
    Medication can clear intestinal worms from the body, including roundworms, the parasites most frequently detected in this study. Campaigns using drugs to de-worm large numbers of people are under way in many parts of the tropics as health officials seek to improve school-age children’s growth and cognitive development, Nutman says.
    The new findings suggest that these de-worming programs could have “an unexpected benefit” in communities with endemic cholera by improving the effectiveness of cholera vaccination, Harris says.
    Cholera infects roughly 5 million people worldwide each year and causes about 100,000 deaths.
    Last edited by sirAdrian; 02-04-2009 at 19:55. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

  20. Back To Top | #20
    Chicks do arithmetic

    Recently hatched fowls appear to add and subtract

    Count your chickens after they hatch, and they may do a little arithmetic themselves.
    Chicks only 3 or 4 days old manage an animal version of adding and subtracting, says Rosa Rugani of the University of Trento Center for Mind/Brain Sciences in Rovereto, Italy.
    Inspired by experiments with human babies, Rugani and her colleagues worked out tests based on adding objects to and taking them away from little piles behind screens. With no special math coaching, the chicks did a decent job of keeping track of object shifts representing such problems as 4 – 2 = 2 and 1 + 2 = 3, she and her colleagues report online March 31 in Proceedings of the Royal Society B.
    “This is the first demonstration of adding and subtracting in young animals” other than humans, Rugani says. Other animals, including some primates and dogs, have demonstrated numerical powers as adults.
    Karen Wynn of Yale University, who has reported evidence of numerical skills in human babies, points out that the chicks haven’t had a chance to learn or develop much. “This work, then, is a compelling existence proof that numerical understanding comprises a built-in system of unlearned knowledge,” Wynn says.
    To invent math tests for young chickens, the researchers took advantage of the chicks’ tendency to cluster. Solo chicks typically rush over to join the largest group of their companions in the neighborhood. Researchers put sets of little plastic balls or bits of colored paper into the cage with a recently hatched chick. “They treat the balls as companions,” Rugani says. At test time, chicks scurry over to the larger group of their ball or paper pals.
    In early, simple tests, researchers found that chicks discriminate between sets of two and three objects. It’s the number three that lures them, not the outline or the total bulk, Rugani says. For example, when researchers let chicks choose between three little pieces of red paper or the same area of paper divided into just two parts, chicks mostly preferred three pieces.
    For the toughest set of tests, each chick watched as a researcher first hid objects behind each of two screens. Then the tester let the chick see some of the objects being moved from behind one screen to the other. To go to the screen with the larger number, the chick had to keep track of addition and subtraction.
    About 75 percent of the time, chicks did it right. For example, researchers put four balls behind one screen and two behind another, and then shifted two of the original four to the pile behind the second screen. Most of the chicks weren’t fooled by that original big flock of four balls. When released to make their choice, most chicks scuttled over to the second screen, which had started with a puny two and now had four.
    “The chick study is powerful because it shows that an animal can use a sense of numbers and basic math with almost no experience on Earth,” says Jessica Cantlon of Duke University in Durham, N.C., who studies numerical powers in primates. The study, she says, “shows that animals might be evolutionarily endowed with an ability to track and manipulate numbers, rather than picking up their numerical abilities gradually over development.”
    Editare ulterioară
    Heavyweight galaxies in the young universe

    Newfound massive galaxies may force theorists to revisit formation models

    Peering into the center of five of the youngest clusters of galaxies known in the universe, astronomers recently found several full-grown, cigar-chomping adults among the myriad of toddlers. The remote galaxies hail from a time when the 13.7-billion-year-old cosmos was less than 5 billion years old. Yet measurements reveal that the bodies are just as massive as galaxies like the modern-day Milky Way, which took at least 10 billions years to mature.
    The findings appear to call into question the leading theory of galaxy formation, known as the dark matter model — at least as it applies to the dense regions where galaxies congregate into clusters, says Chris Collins, an astronomer at the Liverpool John Moores University in England. He and his colleagues used the infrared Subaru telescope atop Hawaii’s Mauna Kea to observe the galaxies, and the team describes the findings in the April 2 Nature.
    “No doubt the theorists will want to say that tweaking [the model] in very dense regions will suffice, but I think the problem could be more general than that,” Collins says.
    The highly successful model holds that the gravity of a proposed, invisible material known as cold dark matter draws together gas and stars to form galaxies. Due to the properties of dark matter, the model always builds tiny, lightweight galaxies first, merging these small-fry to make bigger bodies. Indeed, dark matter simulations suggest that at such a young age, the galaxies the team examined should have attained only 20 percent of the weight that the astronomers observed.
    In the dense environment of a cluster galaxy formation is predicted to occur more quickly. Nonetheless, there doesn’t seem to have been enough time, some 4 billion to 5 billion years after the Big Bang, for the five massive galaxies to have formed by the merging of smaller galaxies, according to the model. The findings suggest that some massive galaxies formed wholesale, rather than building up stars and gas little by little as they cannibalized their neighbors.
    “These observations are certainly surprising,” comments theorist Gus Evrard of the University of Michigan in Ann Arbor. Although more data and even larger-scale simulations are needed to determine whether the observations and theory are truly inconsistent, “the difference between nature’s brightest cluster galaxies and the simulated sample is quite striking,” he adds.
    Evrard is a collaborator on the Millennium Simulation, an international effort that combines the largest supercomputer simulation of the growth of dark matter ever attempted with new techniques for tracking the evolution of the visible universe. Collins’ team directly compared its observations with the masses of galaxies predicted by this simulation when the universe was about one-third its current age.
    “Our result is strong evidence that, for reasons we as yet do not understand, the process of galaxy assembly at early times was much more rapid and efficient than the [dark matter model] in the simulations would have us believe,” Collins says. Although the dark matter scenario for galaxy formation accurately predicts many features over a wide range of cosmic history, “it seems that in these extreme cluster environments, something else is needed.”
    In the dense regions examined by Collins’ team the simulations predict extremely rapid growth. But even in these regions the masses of the galaxies were much heavier than the model allowed.
    Over the past few years, other astronomers have peered even further back in time and also found some monster galaxies among the newborns (SN: 10/8/05, p. 235). These heavyweights, although less massive than the ones found by Collins and his colleagues, would have had much less time to bulk up and could have put even tighter limits on models of galaxy formation. However, theorists argue that dark matter models allow a few statistical oddballs. Modelers explain away the handful of early massive galaxies as extremely rare objects that happened to be in the densest dark matter regions, Collins says.
    In contrast, galaxy clusters aren’t rare. Moreover, the rapid growth rate of galaxies in clusters is already included in the Millennium Simulation.
    One reason that the dark matter model may fail to produce massive galaxies rapidly is that at high densities, nearby gas gravitationally snared by a young galaxy would be compressed quickly and heated. Hot gas cannot form stars and in addition would likely loiter in the halo of the young galaxy rather than sinking toward the center to add to the system’s mass.
    A report in the Jan. 22 Nature by Avishai Dekel of the Hebrew University of Jerusalem and his colleagues offers a possible solution to this cosmic conundrum (SN: 3/22/08, p. 186). His team’s high-resolution simulations show that some gas funnels toward the center of the galaxy before the gas heats up and can therefore make stars. That would mean that galaxies could bulk up more efficiently in the past.
    “Dekel’s stuff points to the underlying difficulties of forming large galaxies quickly and suggests a nice possible way out, but even here it may not be the last word,” Collins says. “I think our data will stimulate more theoretical work.”
    In their models, theorists could also attempt to ramp up the rate at which gas turns into stars in the brightest members of galaxy clusters, Evrard suggests. However, he cautions that it could be difficult to fatten up only the brightest members while leaving neighboring galaxies svelte. “The unintended consequence could be gigantic galaxies in today’s universe that aren’t seen and they certainly would be easy to see,” he says.
    Speaking of the distance to the observed galaxies, Evrard says, “The observers have laid out a 10 billion light-year tightrope and challenged the theorists to balance on it. It may not be easy.”
    Last edited by sirAdrian; 02-04-2009 at 19:56. Reason: Automerged Doublepost
    Am căutat răspunsuri şi-am găsit alte întrebări, cele mai mari secrete ascunse într-o zi de ieri, nu vreau păreri vreau certitudini, capul pe umeri, nimeni nu-nvaţă din greşeli învaţă să le numeri.

Page 1 of 25 123411 ... LastLast



Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts