A Blog Around The Clock

Teens Who Do Use Condoms Often Don’t Use Them Properly:

A worrying number of young people who do use condoms don’t use them correctly, so risking unwanted pregnancy or infections, reveals research published ahead of print in the journal Sexually Transmitted Infections. But a good relationship with their mothers seemed to be associated with correct condom use, the research showed.

Paleontologist Discovers South American Mammal Fossils:

Fossils of a new hoofed mammal that resembles a cross between a dog and a hare which once roamed the Andes Mountains in southern Bolivia around 13 million years ago was discovered by Darin A. Croft, assistant professor of anatomy at the Case Western Reserve University School of Medicine and a research associate at the Cleveland Museum of Natural History.

Pressure To Be More Muscular May Lead Men To Unhealthy Behaviors:

New research suggests that men feel pressure to have muscular bodies, and that influence can lead some to symptoms of eating disorders, pressure to use steroids, and an unhealthy preoccupation with weightlifting.
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“Instead of seeing a decrease in objectification of women in society, there has just been an increase in the objectification of men. And you can see that in the media today,” she said.

Light Guides Flight Of Migratory Birds:

Songbirds use multiple sources of directional cues to guide their seasonal migrations, including the Sun, star patterns, the earth’s magnetic field, and sky polarized light patterns. To avoid navigational errors as cue availability changes with time of day and weather conditions, these “compass” systems must be calibrated to a common reference. Experiments over the last 30 years have failed to resolve the fundamental question of how migratory birds integrate multiple sources of directional information into a coherent navigational system.
Last autumn, Rachel Muheim, a postdoctoral associate in biology professor John Phillips’ lab at Virginia Tech, captured Savannah sparrows in the Yukon before they headed south. She was able to demonstrate that the birds calibrate their magnetic compass based on polarized light patterns at sunset and sunrise.
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Polarized light is light that oscillates in one plane relative to the direction of propagation. At sunrise and sunset, there is a band of intense polarized light 90 degrees from the sun that passes directly overhead through the zenith and intersects the horizon 90 degrees to the right and left of the sun. Just as the sun location changes with latitude and the time of year, so does the alignment of the band of polarized light.
Muheim and Phillips argue that migratory songbirds average the sunrise and sunset intersections of the polarization band with the horizon to find the north-south meridian (geographic north-south axis), providing a reference that is independent of time of year and latitude. The birds then use this geographic reference to calibrate their other compass systems.
In other words, polarized light, the Sun and stars, and the geomagnetic field are all directional cues for migration, but polarized light appears to provide the primary reference system used to calibrate the other compass systems, said Phillips.
However, previous research had suggested a much more confusing picture.
Migratory birds are born with an innate magnetic compass preference that coincides with their species’ migratory direction. Previous research suggested that before the migration period, songbirds are able to recalibrate the magnetic compass when exposed to a “conflict” between magnetic and celestial (including polarized light) cues, but during migration it appeared that the reverse was true, — the magnetic field was used as the primary reference for calibrating the birds’ other compass systems. But in a few experiments with birds during migration, the birds did recalibrate the magnetic compass.
When Muheim and Phillips did a literature review, they noticed a difference between the experiments of the few scientists who saw migratory birds recalibrate their compass and of those whose birds failed to recalibrate.
“It is important how you do the experiments. It turns out that the part of the sky that matters is just above the horizon,” said Phillips. “In cue conflict experiments carried out before migration, birds were usually housed in outdoor aviaries in a rotated magnetic field, where they had a view of the whole sky, including the horizon. Once migration starts, however, scientists usually exposed birds in “funnel cages”. This is so, after exposure to the cue conflict, the birds’ directional preferences could be recorded; songbirds in migratory condition leave tracks or scratches on the sides of the funnel as they attempt to take flight in the migratory direction. A problem arises, however, because funnels block the lower 20 degrees of the sky. In the only two experiments (out of 30 or so) carried out during migration where birds were exposed to the cue conflict with a view of the horizon, they did recalibrate their magnetic compass — just as was previously observed only in experiments carried out prior to migration.”
Muheim’s experiments proved that seeing polarized light cues near the horizon was the critical factor. “Once the right hypothesis came along, it all fit,” said Phillips.

Dominant Meerkats Render Rivals Infertile:

When pregnant, dominant female meerkats subject their subordinates to escalating aggression and temporary eviction causing them to become overly stressed and as a result infertile, a new study finds.

Does Environment Influence Genes? Researcher Gives Hard Thoughts On Soft Inheritance:

Organisms, including humans, all inherit DNA from generation to generation, what biologists call hard inheritance, because the nucleotide sequence of DNA is constant and only changes by rare random mutation as it is passed down the generations.
But there also is evidence, especially in plants, that non-genetic factors modifying the DNA can also be inherited. The modifications of the genetic material take the form of small chemical additions to one of the DNA bases and the alternative packaging of the DNA. These so-called epigenetic modifications are known to be important for turning genes on and off during the course of an organism’s life, but their importance in controlling inheritance has been debated. Many biologists are skeptical of any form of soft inheritance, where the genetic material is not constant, believing that it is only genetic information – DNA — that can be passed onto generations.
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“To get to the issue of the more extreme variations of soft inheritance, it has to be determined whether the environment can induce an epigenetic change in an organism that can be inherited in subsequent generations. Certainly, nobody has shown that an epigenetically induced beneficial or adaptive change has been inherited. Mechanistically, there is no reason to discount epigenetic inheritance. The biochemical nuts and bolts are there to support it. The big questions to resolve are how many epigenetic changes are induced by the environment, what types of phenotypes result from these changes, and how many of these epigenetic changes are inherited.”

Kids Need More Time Than Adults Give Them, Study Finds:

Further proof that children require more time comes via a study to be published today in Developmental Science asserting that the fast pace expected by adults–both parents and educators–can be beyond chindren’s perceptual abilities.
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“We expect children to be adult-like, because of their proficiency on computers or because they display adult-like speech,” he says, “so we give them instructions and get impatient when they can’t understand what we tell them the first time. Children learn through repetition, at a pace suitable to the child, not to the curriculum. Once upon a time, kids controlled their own pace; now that pace is controlled by adults.”

Scientists Learn How The Brain ‘Boots Up’ To Process Information From The Senses:

The same chemical in the body that is targeted by the drug Viagra® also helps our brains “boot up” in the morning so we can process sights, sound, touch and other sensory information. The discovery could lead to a better understanding of major brain disorders, according to researchers from Wake Forest University School of Medicine.
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“We expected to find that signals from the eye would be boosted by nitric oxide,” said Godwin. “Instead, we found that nitric oxide reduced signals from the eyes, and enhanced the feedback from the cortex. The tiny molecule appears to allow the cortex to exert more control on how much information it receives from the thalamus.”

Infants, As Early As Six Months, Do See Errors In Arithmetic:

Using advanced brain sensor technology developed at the University of Oregon, researchers have confirmed often-debated findings from 1992 that showed infants as young as six months know when an arithmetic solution is wrong.

Imaging Study May Help Point Toward More Effective Smoking Cessation Treatments:

Results of a new imaging study, supported in part by the National Institute on Drug Abuse (NIDA), National Institutes of Health, show that the nicotine received in just a few puffs of a cigarette can exert a force powerful enough to drive an individual to continue smoking. Researchers found that the amount of nicotine contained in just one puff of a cigarette can occupy about 30 percent of the brain’s most common type of nicotine receptors, while three puffs of a cigarette can occupy about 70 percent of these receptors. When nearly all of the receptors are occupied (as a result of smoking at least 2 and one-half cigarettes), the smoker becomes satiated, or satisfied, for a time. Soon, however, this level of satiation wears off, driving the smoker to continue smoking throughout the day to satisfy cigarette cravings.

Researcher Studies Sleep Deprivation’s Effect On Decisions:

Everyone needs sleep, but temporary periods with no sleep can be a reality of military operations. To get answers on sleep questions for the military as well as civilians, for nearly four years Dr. Sean Drummond, a Department of Defense-funded researcher, has studied the effects of sleep deprivation on the brain, namely in decision making, as well as how long it takes to recover from periods of no sleep.

Early Exposure To Synthetic Estrogen Puts ‘DES Daughters’ At Higher Risk For Breast Cancer:

So-called “DES daughters,” born to mothers who used the anti-miscarriage drug diethylstilbestrol during pregnancy, are at a substantially greater risk of developing breast cancer compared to women who were not exposed to the drug in utero.

Scientists Solve Sour Taste Proteins:

A team led by Duke University Medical Center researchers has discovered two proteins in the taste buds on the surface of the tongue that are responsible for detecting sour tastes.

Scientists Reverse Evolution: Ancient Gene Reconstructed From Descendants:

University of Utah scientists have shown how evolution works by reversing the process, reconstructing a 530-million-year-old gene by combining key portions of two modern mouse genes that descended from the archaic gene.

I am not sure if “reversing evolution” is the correct term to be applied here, except in making an eye-catching title for this article…
Update: PZ Myers explains the study in detail (and agrees that this is not “evolution in reverse”).
Researchers Find New Learning Strategy:

Central to being human is the ability to adapt: We learn from our mistakes. Previous theories of learning have assumed that the size of learning naturally scales with the size of the mistake. But now biomedical engineers at Washington University in St. Louis have shown that people can use alternative strategies: Learning does not necessarily scale proportionally with error.

Nicotine Found To Protect Against Parkinson’s-like Brain Damage:

New research suggests that nicotine treatment protects against the same type of brain damage that occurs in Parkinson’s disease. The research was conducted in laboratory animals treated with MPTP, an agent that produces a gradual loss of brain function characteristic of Parkinson’s. Experimental animals receiving chronic administration of nicotine over a period of six months had 25 percent less damage from the MPTP treatment than those not receiving nicotine.

Dunno….did smoking help my Dad live a little longer?
http://www.sciencedaily.com/releases/2006/08/060807154944.htm:

No matter how you slice it, the freshwater planarian possesses an amazing ability to regenerate lost body parts. Chop one into pieces, and each piece can grow into a complete planarian. The flatworm relies upon a population of stem cells to accomplish this remarkable feat; recent work sheds light on how planarians maintain these stem cells throughout their lives.

Brain Stimulation That May Boost Vision From The Corner Of Your Eye:

By using simultaneous brain stimulation and activity recording to track the influence of one brain region on another, researchers have developed a new method for boosting brain function that may have implications for treatments of brain disorders and for improving vision. The findings are reported by Christian Ruff, Jon Driver, and their colleagues at University College London and appear in the August 8th issue of Current Biology, published by Cell Press.

Ancient Bison Teeth Provide Window On Past Great Plains Climate, Vegetation:

A University of Washington researcher has devised a way to use the fossil teeth of ancient bison as a tool to reconstruct historic climate and vegetation changes in America’s breadbasket, the Great Plains.

The Shape Of Life: Research Sheds Light On How Cells Take Shape:

How life takes shape is a mystery. Butterfly or baby, cells organize themselves into tissues, tissues form organs, organs become organisms. Over and over, patterns emerge in all living creatures. Spiders get eight legs. Leopards get spots. Every nautilus is encased in an elegant spiral shell.
This phenomenon of pattern formation is critical in developmental biology. But the forces that govern it are far from clear. Alan Turing, father of modern computer science, suggested that the basis for pattern formation was chemical. New research conducted at Brown University and published in the Proceedings of the National Academy of Sciences supplies another surprising answer: Physical, as well as chemical, forces can dictate pattern formation.

Surprising? Since when? D’Arcy Thomspon?