Tag: field (page 6 of 42)

Did natural selection make the Dutch the tallest people on the planet?

Dutch national women's field hockey team



Excerpt from news.sciencemag.org
ByMartin Enserink

AMSTERDAM—Insecure about your height? You may want to avoid this tiny country by the North Sea, whose population has gained an impressive 20 centimeters in the past 150 years and is now officially the tallest on the planet. Scientists chalk up most of that increase to rising wealth, a rich diet, and good health care, but a new study suggests something else is going on as well: The Dutch growth spurt may be an example of human evolution in action.
The study, published online today in the Proceedings of the Royal Society B, shows that tall Dutch men on average have more children than their shorter counterparts, and that more of their children survive. That suggests genes that help make people tall are becoming more frequent among the Dutch, says behavioral biologist and lead author Gert Stulp of the London School of Hygiene & Tropical Medicine.

"This study drives home the message that the human population is still subject to natural selection," says Stephen Stearns, an evolutionary biologist at Yale University who wasn't involved in the study. "It strikes at the core of our understanding of human nature, and how malleable it is." It also confirms what Stearns knows from personal experience about the population in the northern Netherlands, where the study took place: "Boy, they are tall."

For many years, the U.S. population was the tallest in the world. In the 18th century, American men were 5 to 8 centimeters taller than those in the Netherlands. Today, Americans are the fattest, but they lost the race for height to northern Europeans—including Danes, Norwegians, Swedes, and Estonians—sometime in the 20th century.

Just how these peoples became so tall isn't clear, however. Genetics has an important effect on body height: Scientists have found at least 180 genes that influence how tall you become. Each one has only a small effect, but together, they may explain up to 80% of the variation in height within a population. Yet environmental factors play a huge role as well. The children of Japanese immigrants to Hawaii, for instance, grew much taller than their parents. Scientists assume that a diet rich in milk and meat played a major role.

The Dutch have become so much taller in such a short period that scientists chalk most of it up to their changing environment. As the Netherlands developed, it became one of the world's largest producers and consumers of cheese and milk. An increasingly egalitarian distribution of wealth and universal access to health care may also have helped.

Still, scientists wonder whether natural selection has played a role as well. For men, being tall is associated with better health, attractiveness to the opposite sex, a better education, and higher income—all of which could lead to more reproductive success, Stulp says.
Yet studies in the United States don't show this. Stulp's own research among Wisconsinites born between 1937 and 1940, for instance, showed that average-sized men had more children than shorter and taller men, and shorter women had more children than those of average height. Taken together, Stulp says, this suggests natural selection in the United States pulls in the opposite direction of environmental factors like diet, making people shorter instead of taller. That may explain why the growth in average American height has leveled off.

Stulp—who says his towering 2-meter frame did not influence his research interest—wondered if the same was true in his native country. To find out, he and his colleagues turned to a database tracking key life data for almost 100,000 people in the country's three northern provinces. The researchers included only people over 45 who were born in the Netherlands to Dutch-born parents. This way, they had a relatively accurate number of total children per subject (most people stop having children after 45) and they also avoided the effects of immigration.

In the remaining sample of 42,616 people, taller men had more children on average, despite the fact that they had their first child at a higher age. The effect was small—an extra 0.24 children at most for taller men—but highly significant. (Taller men also had a smaller chance of remaining childless, and a higher chance of having a partner.)  The same effect wasn't seen in women, who had the highest reproductive success when they were of average height.  The study suggests this may be because taller women had a smaller chance of finding a mate, while shorter women were at higher risk of losing a child.

Because tall men are likely to pass on the genes that made them tall, the outcome suggests that—in contrast to Americans—the Dutch population is evolving to become taller, Stulp says. "This is not what we've seen in other studies—that's what makes it exciting," says evolutionary biologist Simon Verhulst of the University of Groningen in the Netherlands, who was Stulp's Ph.D. adviser but wasn't involved in the current study. Verhulst points out that the team can't be certain that genes involved in height are actually becoming more frequent, however, as the authors acknowledge.

The study suggests that sexual selection is at work in the Dutch population, Stearns says: Dutch women may prefer taller men because they expect them to have more resources to invest in their children. But there are also other possibilities. It could be that taller men are more resistant to disease, Stearns says, or that they are more likely to divorce and start a second family. "It will be a difficult question to answer.”

Another question is why tall men in Holland are at a reproductive advantage but those in the United States are not. Stulp says he can only speculate. One reason may be that humans often choose a partner who's not much shorter or taller than they are themselves. Because shorter women in the United States have more children, tall men may do worse than those of average height because they're less likely to partner with a short woman.

In the end, Stearns says, the advantage of tall Dutchmen may be only temporary. Often in evolution, natural selection will favor one trend for a number of generations, followed by a stabilization or even a return to the opposite trend. In the United States, selection for height appears to have occurred several centuries ago, leading to taller men, and then it stopped. "Perhaps the Dutch caught up and actually overshot the American men," he says.

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DEEPLY AWAKE By Kathy Vik Field Report 4 April 2015

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Radio bursts from space reveal strange mathematical pattern





Excerpt from foxnews.com

Eleven fast radio bursts from space seem to follow a strange mathematical pattern, according to a new study – and it has researchers scratching their heads. 

According to study co–authors Michael Hippke of the Institute of Data Analysis in Neukirchen-Vluyn,  Germany, and John Learned of the University of Hawaii in Manoa, the bursts– which were first detected in 2001 – all had dispersion measures that were integer multiples of the same number: 187.5. “The astronomers that found [the bursts] have not seen such things before and do not understand them,” Learned told FoxNews.com.

Nobody knows what causes fast radio bursts, known as FRBs. They only last a few milliseconds, and only one so far has been captured live (by the Parkes Telescope in Australia last year). Though the bursts release just as much energy in a few milliseconds as the sun does in a month, their brevity indicates that the source must be small, with estimates being several hundred miles across at most.

Researchers use dispersion measures, which records how much “space gunk” the burst has passed through, to estimate the distance an FRB has travelled. For instance, a low frequency FRB will have more gunk on it, indicating a longer trip, whereas a high frequency FRB will be cleaner, indicating it came from closer to Earth.
The fact that all of the FRBs’ dispersion measures are integer multiples of 187.5 has, according to Hippke and Learned’s team’s calculations, a 5 in 10,000 chance of being coincidental. The dispersion measures also indicate that their origin is relatively close to Earth, but unlikely from within our own galaxy.

There are numerous theories on where these bursts came from, including speculation that the messages are from extraterrestrial intelligence. To the scientific community, however, this theory doesn’t really hold water, and is seen as more of a last resort only after all other avenues have been exhausted.

“We think these are likely from some very energetic process, like a burst from a high magnetic field neutron star or energy released [when] two neutron stars merge,” Professor Maura McLaughlin of the West Virginia University Center for Astrophysics explained. “The thing that made people think they were possibly from ETs was a recent paper that showed that one fundamental property is quantized in a way that wouldn't be expected if the signals were naturally occurring. However, I imagine that correlation will totally go away once more are discovered.”

Learned himself is dubious of an alien source as well, noting that he and Hippke only noted the dispersion measures’ “peculiar” pattern, and that they may even be coming from Earth. “We are now leaning more towards a terrestrial, anthropogenic interpretation,” he said. “At this point I would place my money on some sort of governmental satellite, not a natural phenomena, but I would not bet much.  More data, which reportedly [is] being analyzed but which we have no insider information about yet, will be most interesting and refute or confirm our hypotheses.” He also noted that he’d only look to an ETI interpretation once all other possibilities have been eliminated.

As for McLaughlin, she believes there’s no way the FRBs could be messages from aliens, as the signals are very broadband and emitted over a wide range of radio frequencies. “It would take a LOT of energy for an alien civilization to produce these bursts - they'd need to harness the energy of many, many suns - and there's no real advantage for communication to send a signal over such a large bandwidth.”

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Frustrated magnets showing features of Hall Effect stun Princeton University researchers


Frustrated-Magnets



Excerpt from worldtechtoday.com

A group of researchers at the Princeton University has found that frustrated magnets, inspite of not possessing any magnetic feature at low temperatures, do exhibit features of Hall Effect. ‘Frustrated’ magnets are so called because of their inability of getting a long range magnetic order inspite of a huge exchange between the spins of their elementary particles.

The Hall Effect suggests that when magnetic field is applied to electric current carried by charged particles present in a conductor, it causes magnet to bend to the other side of semi-conductor. They are of great interest in physics and material science. Appreciating that frustrated magnets are capable of producing Hall Effect could hold the key to future advances in computing and the creation of devices such as quantum computers.

“To talk about the Hall Effect for neutral particles is an oxymoron, a crazy idea,” said N. Phuan Ong, one of the authors of the study and Eugene Higgins Professor of Physics at Princeton.

Inspite of that, he together with his colleague, Princeton’s Russell Wellman Moore Professor of Chemistry as well as their graduate students Max Hirschberger and Jason Krizan witnessed this unusual behavior in frustrated magnets.

“All of us were very surprised because we work and play in the classical, non-quantum world. Quantum behavior can seem very strange, and this is one example where something that shouldn’t happen is in reality there. It really exists,” said Ong in a statement.
The researchers wanted to find out the reason underlying “discontent” nature of Hall Effect.

In this particular case, the team led by Ong and Moore studied pyrochlores, a class of magnets ‘which should have orderly “spins” at very low temperature, but have been found to have spins that point in random directions, thus rendering them with magnetic frustration properties.’ They attached small electrodes to both sides of crystals and later passed heat through them using microheaters at extremely low temperatures.

The outcome of the experiment, states Ong, stunned the entire team.

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Science of frustrated magnets: Hall Effect experiment reveals clues to their discontent

Excerpt from thewestsidestory.netA scientific study carried out in Princeton has brought about the discovery of unlikely properties in materials called frustrated magnets using the Hall Effect.Hall Effect is the property of magnetic fields having inf...

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Galactic Federation of Light SaLuSa March 29 2015

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Boeing to Create a Star Wars-like Forcefield (Yes, an actual forcefield) ~ Video

Excerpt from usatoday.comStar Wars jokes aside, Boeing actually just patented a force field that would use energy to deflect explosions. For real; it's called, "method and system for shockwave attenuation via electromagnetic arc."According to the pat...

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New spin on Saturn’s peculiar, err, spin

 Excerpt from spacedaily.comAccording to the new method, Saturn's day is 10 hours, 32 minutes and 44 seconds long. Tracking the rotation speed of solid planets, like the Earth and Mars, is a relatively simple task: Just measure the time it tak...

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