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Topics - ABM Nazmul Islam

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16
Faculty Sections / Tailored Egyptian dress is the oldest ever found
« on: March 09, 2016, 12:11:36 PM »
It’s the ultimate in retro fashion — an Egyptian woven dress that is now considered the oldest known piece of cut, fitted and tailored clothing. Radiocarbon dating puts the dress, recovered from an ancient Egyptian cemetery called Tarkhan, at between 5,100 and 5,400 years old.

Analysis of a 2-centimeter-long thread from the V-necked, linen dress with pleated sleeves yielded the new radiocarbon age estimate. Examples of similar, floor-length Egyptian dresses date to nearly 5,000 years ago, says archaeologist Alice Stevenson, curator of University College London’s Petrie Museum of Egyptian Archaeology, home to the Tarkhan Dress.

Stevenson and Michael Dee of the University of Oxford report the garment’s age online in the February Antiquity Project Gallery.

Stevenson suspects a socially elite woman wore the Tarkhan Dress shortly before Egypt’s first dynasty of kings appeared around 5,100 years ago. Tailored clothes might have been made even earlier. Tailors and other craft specialists emerged in societies where royals sought prestige goods, Stevenson suggests. Comparably old woven fabric from Jordan and Peru was draped or wrapped around the body, rather than cut to fit, she adds.

17
Faculty Sections / The dodo was no dummy
« on: March 09, 2016, 12:11:01 PM »
A 3-D model of the brain of the long-extinct dodo suggests that the birds may have been fairly intelligent — by bird standards.

Overhunting and habitat loss drove dodos (Raphus cucullatus) extinct about a century after humans invaded their island home, Mauritius, in 1507. The flightless birds appeared unafraid of human explorers, hence their reputation for stupidity.

Researchers at the American Museum of Natural History in New York City and the Natural History Museum of Denmark in Copenhagen performed CT scans on a dodo’s skull and digitally reconstructed its outer brain structure. They did the same for eight other members of the pigeon family.

Dodos, it seems, had unusually large olfactory bulbs, which may have helped them sniff out fresh fruits, tiny mollusks and insects. Overall, the ratio of the dodo’s brain size to its body size — an indirect measure of intelligence — is on par with that of its pigeon relatives, the researchers report February 23 in the Zoological Journal of the Linnaean Society.

18
One of England’s oldest artworks turned up last year on a tiny piece of stone.

An engraved shale pendant unearthed at Star Carr, a site under excavation since 1947, dates to around 11,000 years ago, a time when Britons were transitioning from foragers to farmers, researchers report online February 25 in Internet Archaeology. The pendant, roughly the size and shape of a guitar pick, includes a carefully fashioned hole through which it may have been strung, say archaeologist Nicky Milner of the University of York and her colleagues.

Many of the pendant’s etched lines are now barely visible. Microscopic analyses determined that the engraved pattern — which includes clusters of short lines connected to long lines — resembles etched designs on amber pendants from around the same time and found in Denmark, southern Sweden and northern Germany.

Milner’s group doesn’t know who made or used the ancient pendant, or what meaning the etched pattern had for its makers. One possibility is that the pendant belonged to a shaman. Headdresses made of red deer antlers found in earlier Star Carr excavations may have been worn by shamans, Milner says.

Star Carr has also yielded shale beads, a piece of perforated amber and two perforated animal teeth. Those finds contain no engravings.

Animal engravings and carved reliefs on the walls and ceilings of several British caves date to at least around 13,000 years ago.

19
Faculty Sections / 3.5 billion years ago, oceans were cool, not hot
« on: March 09, 2016, 12:09:41 PM »
About 3.5 billion years ago, Earth’s oceans were cool, not inhospitably hot as previously thought. In fact, the entire planet at the time was probably locked in a cold snap that lasted at least 30 million years, a new study concludes. The findings, published online February 26 in Science Advances, could change the view of Earth’s ancient climate and life’s earliest years.

“This is the first evidence that over the entire [last] 3.5 billion years, Earth has operated within a temperature range that suits life,” says Maarten de Wit, a geologist at Nelson Mandela Metropolitan University in Port Elizabeth, South Africa.

Evidence for this big chill was found in South Africa’s Barberton Greenstone Belt, which contains some of the oldest, best preserved rocks on Earth. Along with Harald Furnes, a geologist at the University of Bergen in Norway, de Wit spent six years mapping and sampling the Barberton. The researchers studied volcanic rock and a kind of silica called chert that formed deep underwater. They also studied shallower sedimentary and volcanic rocks deposited 30 million years after the deep ocean rocks.

The researchers analyzed hundreds of these rock samples for the concentration of oxygen-18 isotopes, an indicator of what the temperature was like when the rocks formed. They also discovered in the younger rocks diamictite — a clay-rich sedimentary rock typically formed in glacial environments — and in the older rocks gypsum, which 3.5 billion years ago would have formed only in deep, cold seas. These findings suggest that both the shallow environment and deep waters were cool. Ambient ocean temperatures must have been close to 0°Celsius, de Wit says. 

CLAY CLUES Among the evidence that researchers found for a cold environment 3.5 billion years ago were varved sediments. Varves are seasonal bands that form when lakes freeze over each winter, slowing sedimentation.
M. DE WIT AND H. FURNES/SCIENCE ADVANCES 2016

Paleomagnetic data point to a colder-than-expected global environment, too, de Wit and Furnes found. As volcanic rock cools, minerals within the rock capture the prevailing magnetic pole direction, which reverses every few hundred thousand years. The data can be used to reconstruct the latitude at which rocks formed — in this case, a nearly tropical 20° to 30°. “Because there was ice near sea level at low latitudes,” de Wit says, “the oceans and atmosphere were globally likely to be cold.”

What’s more, de Wit and Furnes figured out why previous researchers had interpreted ocean temperatures to be 30° C to 80° C during this time (compared with near 0° C to about 16° C for modern oceans). Two periods of searing-hot hydrothermal activity had cooked both the seafloor cherts and the surface glacial sediments. In the older seafloor sediments from the Barberton, the team discovered hard evidence for hydrothermal vents. Earlier studies had focused mainly on oxygen isotopes from limited samples that happened to have been strongly affected by this hydrothermal activity, and researchers had not recognized that the results revealed local, not ambient, ocean temperatures.

That, says de Wit, was like looking at data from Yellowstone hot springs and extending it to an entire ocean. By sampling a much broader area, he and Furnes determined that the superheating effects of hydrothermal activity had been strictly local. “You really have to map carefully and do a lot of isotope follow-up work to test it all,” he says.

The study has implications for how life may have evolved. While hot oceans would have been largely inhospitable, de Wit says that hydrothermal fields in a cool ocean would have provided a nurturing environment for bacteria, just as scientists see today around deep ocean hydrothermal vents.

“I believe this study is quite significant,” says Yale University geochemist Ruth Blake, who has studied the Barberton, too. The researchers “present compelling new evidence that advances our understanding of one of the most highly-debated periods in Earth's history.”

20
Super Tuesday is nigh, and if you watch TV the old-fashioned way (with commercials), candidate ads are as common as (and mimicked in) pitches for airlines, beer and upcoming films. As tempting as it is to turn the volume down during ad time, I urge you, dear reader, to pay attention to who’s talking. It turns out that a standout in political ad strategery is the use of male versus female narrators.

Several years ago, a team of researchers looked into differences in how male and female Congressional candidates presented themselves in campaign ads — for example, whether the ad cited sources (like newspapers), the ad setting, or thematic differences conveyed by the appearance of, say, children, law enforcement officers or the candidate’s relatives. The team was surprised to find that there really weren’t gender-related idiosyncrasies.

“We thought that maybe men would do this and women would do that,” Patricia Strach, an expert in social and political behavior at the University at Albany, State University of New York, told me. “But there just aren’t differences in the way that men and women run. They all run as candidates.”

Then, a couple of years ago, Strach and her colleagues decided to look specifically at voiceovers in campaign ads. They tapped into the thousands of political ads archived at the Wesleyan Media Project, which are tagged with data including the date,time, market, station, and television show during which the ad aired. The Media Project also codes each ad with content-related data, such as the ad’s tone (negative, for example), music, issues discussed and the gender of the narrator in voiceovers. For a subset of the ads, the team also had data from more than 80,000 respondents asked to evaluate various ads’ credibility.

And here the researchers did find gender-related differences. The analysis of political ads from the 2012 and 2010 U.S. Congressional elections, published last year in Political Communication, revealed that the choice of narrator in campaign ads indeed reflect gender stereotypes associated with various issues. (Shocker, I know.) The research also revealed that while a female narrator voiceover is perceived as more credible in certain contexts, campaigns ads overwhelmingly use male voiceovers to convey their message.

“It’s this weird paradox,” says Strach. Their initial look into different campaign styles of men and women candidates had found nothing. “But in the voiceovers there was this overwhelming difference. Men’s voices dominate. Yet there’s no good reason for this. In fact, in certain contexts, a women’s voice is more effective.”

Based on previous scholarship, the researchers had generated some working hypotheses. For example, given stereotypes about men being assertive and women being compassionate, ads addressing traditional “feminine” issues, such as education, child care and reproductive rights, might be seen as more credible if voiced by a women, whereas ads about “masculine” issues such as national defense, the economy and foreign policy should be voiced by men. (Considering the thorniness of assigning gender to an issue, the team used Pew Research Center data in which men and women were asked rank issues in order of importance, to categorize each issue.)

And, in fact, ads discussing feminine issues were more likely to be voiced by women and masculine issues by men. Women’s voices were also more likely to be used for contrast ads (this candidate does x, but I do y) and negative ads, perhaps to soften the attack and avoid backlash, the team speculates.

Contrary to their expectations, the researchers found that Republican candidates were more likely to use a woman’s voice than Democrats. Male candidates were also more likely to use a woman’s voice in ads than female candidates, choices that might reflect a strategic effort to give candidates broader appeal.

The biggest surprise however, was that despite their well-oiled machinery, political campaigns don’t make voiceover choices as effectively as they could. There was an overwhelming use of male narrators: In ads using voiceovers, male voices outnumbered female voices by more than 2 to 1. Yet when the researchers look at effectiveness, respondents were more swayed by ads using female voices when the issue was “feminine” AND when the issue was neutral.

My unofficial survey suggests these trends still hold in the current race: Listen to this Ted Cruz ad bashing Trump’s Planned Parenthood record, or this Jeb Bush ad suggesting it’s manly to stand up to Trump. (It’s harder to apply the metrics to the Democratic ads. The candidates tend to do their own talking and Hillary and Bernie are both n=1 in their own special way: Hilary has serious foreign policy chops, for example, and Bernie has made economic issues the center of his platform.)

So if you’re a campaign strategist choosing a narrator, don’t to be so quick to default to a male voice. If you’re a voter, don’t just scrutinize the imagery in advertising; pay attention to the more subtle ways that campaigns and interest groups might be trying to play you.

And even if you’re a cynic like me, keep in mind that political advertising can be a force for good. There’s a lot of evidence that campaign advertising is crucial in informing the electorate, says study coauthor Erika Franklin-Fowler, who also directs the Wesleyan Media Project. “Advertising that provides information on candidate positions and policies — especially ads that may scare the electorate a little — helps to convey that something important is at stake,” Franklin-Fowler told me. “This may lead citizens to go out and seek more information, which is important.”

21
Most people don’t live close to a coral reef. If we want to visit one, we have to travel far, to the tropical waters that are home to these beautiful and diverse ecosystems. But, it turns out, most coral reefs aren’t that far from people. And it’s those really accessible reefs that we should be worrying about, a new study argues.

Eva Maire of the University of Montpellier in France and colleagues started by breaking up all of the world’s coral reefs into 1-kilometer-square cells. They then calculated how much travel time sat between each of those cells and the nearest human settlement, doing their best to account for whether a person would have to use a boat, a road or a meager track to reach the reef.

Fifty-eight percent of the cells are less than 30 minutes from people, the group reports February 15 in Ecology Letters. Most of those reefs can be found in the Caribbean, the Coral Triangle off Southeast Asia, the Western Indian Ocean and around islands in the Pacific. Others, such as those in the Coral Sea or the northwest Hawaiian Islands, are largely inaccessible, requiring 12 hours or more to reach — too far for a quick fishing jaunt. 

Being close to people means that a reef and its resources can be more easily accessed and exploited. Proximity to a market — a source of income for fishermen with easy access to a rich catch — may make that even easier. The researchers found that a quarter of the reefs were within four hours of a major market, and nearly a third were more than 12 hours away. And how close a reef sat to a market appears to matter when it comes to the amount of fish swimming on the reef — those that are closer have lower amounts of fish, the team calculated.

Then the group looked at the pattern of protection for reefs. Many reefs are in marine protected areas that have been set up to limit exploitation. But the reefs most likely to be in a protected area are those that are far from people. An isolated coral reef is more than twice as likely to be protected than average.

The pattern is easy to explain. To set up a protected area, a government has to get everyone who is using that swath of ocean — for fishing, recreation, tourism or anything else — on board with the restrictions that will be placed on usage. And it’s a lot easier to do that with remote patches that not many people are using.

The problem with this, Maire and her colleagues note, is that it means that we may be protecting areas of the ocean that don’t really need protection. And it’s possible that the global goal of protecting 10 percent of the ocean by 2020 “can be met without actually reducing human impacts on the seascape,” they write.

There needs to be more work analyzing the pattern of marine protected areas before any such conclusion can be drawn. And there’s also something to be said for protecting coral reefs now, before they’re totally exploited. Corals already face an uphill battle for survival, given the threats of climate change and ocean acidification. Setting some reefs aside before fishermen and others can do damage doesn’t seem like a bad idea.

22
Faculty Sections / Bubble blowing gets scientific scrutiny
« on: March 09, 2016, 12:07:28 PM »
There’s a science behind the art of blowing soap bubbles.

It’s not the thickness of the soapy film but rather the speed of the blowing gust of air that determines whether bubbles will emerge, scientists in France report in the Feb. 19 Physical Review Letters.

“We have all blown soap bubbles,” says study coauthor Laurent Courbin, a physicist at the University of Rennes in France. “It’s nice to be able to explain simple experiments that we have all experienced in our lives.”

Courbin and his colleagues looked through centuries of studies, but they couldn’t find any explanation of the physics behind bubble blowing. So the team built a device that pumps a controlled, uniform layer of bubble liquid over a roughly 1-meter-high opening of adjustable width. The scientists peppered this large, precise cousin of a bubble wand with pressurized jets of air, light helium or heavy sulfur hexafluoride gas. Quick gusts pushed out bubbles, but slow-moving jets only dimpled the film. 

The scientists came up with a set of equations that predict this minimum speed cutoff under different conditions — for example, when a gas-pumping nozzle is placed right against the bubble layer or when a gust is wider than the film itself (testing that required the use of smaller circular bubble wands).


Factors including the density of the gas, the width of the soapy film and how far a gas-blowing nozzle was from the film determined how fast a gas jet had to travel to make a bubble, the team found. So did nozzle size: The researchers blew bubbles of increasing size starting with tubes smaller than a millimeter across and going up to wind tunnels as big as 20 centimeters wide. For most experiments, the minimum speed that it took to blow a bubble ranged from 10 meters per second to 100 meters per second. 

23
High-voltage electricity surging through undersea power cables doesn’t bother local sea life, three new studies suggest. The work eases concerns that planned offshore power production from wind turbines and tidal generators would disrupt marine communities.

Tracking the movements of fish and crabs around underwater power cables, the new studies reveal that marine critters don’t shy away from the magnetic fields put off by the cables. One study even found that the thick cables can serve as artificial habitats and host undersea communities.

“There’s much less of a concern now,” said Ann Bull, a marine biologist at the Bureau of Ocean Energy Management in Camarillo, Calif., who presented two of the studies February 26 at the American Geophysical Union’s Ocean Sciences Meeting.

In the 1980s, the first underwater telecommunications cables clashed with marine life: Sharks intrigued by electric fields put off by the wires would gnaw on the cables, often leaving teeth behind. Wrapping the cables in insulating material blocked the electric fields and stemmed shark attacks, but magnetic fields generated by the cables remained. Laboratory experiments show that many marine creatures can sense even relatively weak magnetism, sparking fears that the cables serve as “electric fences” that disrupt sea life.


Commercial fishers particularly worried that crabs wouldn’t cross undersea cables to find bait in crab traps. To test this, Bull and her colleagues built cages with two baited traps, one of which required crabs to pass over an active power line. Both Dungeness crabs (Metacarcinus magister) and rock crabs (Romaleon antennarium) had no problem crossing the line: In hundreds of trials, the crabs chose each trap around half the time.

24
The fossilized remains of an about 520-million-year-old creepy-crawly provides a portrait of an ancient arthropod’s nervous system.

Researchers first described Chengjiangocaris kunmingensis — an ancient relative of spiders, insects and crustaceans unearthed from a fossil bed in southern China — in 2013. Further imaging and investigation of five new fossilized specimens reveal exceptionally well-preserved soft tissue and a ropelike structure running down the animal’s belly. That structure is the remains of a ventral nerve cord, Xi-guang Zhang of Yunnan University in Kunming, China, and colleagues explain February 29 in the Proceedings of the National Academy of Sciences.

In invertebrates, a nerve cord serves the same function as our spinal cord. In C. kunmingensis, bundles of ganglia and connective tissue form the cord just like in today’s tardigrades. Each bundle probably controlled a pair of itty-bitty legs, the researchers write. What appear to be individual peripheral nerves shoot off from the nerve cord, resembling the segmented nerve roots seen in penis worms and velvet worms.

The ancient critter’s nervous system adds to our understanding of the broader evolution of nervous systems in modern invertebrates, the researchers write.

25
A couple of years ago, biologists from Washington State University found that killing a wolf to rid a threat to livestock actually increased the chances that cattle or sheep would be killed in the following year. Only eliminating a quarter or more of the wolves in a state resulted in declines in wolves killing livestock.

Ranchers have long killed wolves to protect their animals, but the study’s results seemed to show that the practice might not be as productive as they’d like. Now a new study of wolves in the Italian Alps shows why keeping packs together could be a good move for ranchers.

Camille Imbert of the University of Pavia in Italy and colleagues wanted to know why wolves kill livestock instead of wild prey. Sheep or cattle might look like an easy meal to us, but that may not be true for wolves. And even if a goat was easy to catch, that might not be a wolf’s sole consideration when looking for something to eat.

The researchers studied a population of wolves in Liguria, in northwest Italy, one of the few European wolf populations that has managed to survive into the 21st century and is now starting to expand its range due to new laws and efforts to restore its habitat. From 2008 to 2013, the team collected 1,457 samples of wolf scat and determined which wolf had left the poop behind and what it had eaten. The scientists also figured out whether or not the wolf had belonged to a pack, which consist of a pair of adults and their offspring.

Wolves that belonged to packs tended to eat more wild boar and roe deer and less goat and other livestock than did single wolves, the researchers report in the March Biological Conservation. Lone wolves — either young wolves that are moving to new territory or the former members of a pack that has been broken up (say, when the leaders were killed) — may not know as well what prey is available in an area as the resident pack and may therefore hunt whatever is available, Imbert and her colleagues write. Packs, it seems, can be pickier and go for wild prey when it’s available.

Not that a pack of wolves won’t hunt livestock. Pack wolves did eat goats and other domestic animals. But it seems at least a little blame can be put on Italian herders, who let goats roam unguarded and free in the mountains. And wolves will readily eat young calves born in open pastures; when birthing is done closer to home, cows tend to be safe from wolves.

To keep livestock from being eaten by wolves, the researchers make a few recommendations: Institute a few more protections for domestic animals. Promote a rich community of wild animals that the wolves can eat. And don’t kill wolves and break up packs. “Removal measures do not solve the problem in the long run,” they write.

26
Fast radio bursts from deep space have never been seen to repeat — until now. 

Ten blasts of radio waves recorded last May and June all come from the same direction, researchers report online March 2 in Nature. So did a signal detected in 2012, say Laura Spitler, an astrophysicist at the Max Planck Institute for Radio Astronomy in Bonn, Germany, and colleagues. All 11 signals were detected at the Arecibo Observatory in Puerto Rico.

Fast radio bursts, or FRBs, last a few milliseconds and, except for one, all appear to originate in other galaxies (SN: 8/9/14, p. 22). For the repeater, each of the signals encountered the same amount of intergalactic plasma, meaning they traveled the same distance. That shared feature makes an ironclad case for a common source, says Duncan Lorimer, an astrophysicist at West Virginia University in Morgantown and co-discoverer of the first FRB, reported in 2007. The question now is what fraction of sources repeat, he says. There may be multiple classes of FRBs, with some recurring and some not, each triggered by something different.

Explanations for what causes FRBs include colliding stellar cores, overzealous pulsars and the collapse of obese neutron stars. A repeating signal rules out one-off scenarios such as collisions. More likely sources are radio eruptions from various types of neutron stars, such as pulsars and magnetars. Pulsars emit a steady beat of radio waves, but some young pulsars, such as the nearby Crab pulsar, occasionally blast out vigorous pulses. Radio telescopes could detect such large blasts from another galaxy, Spitler says.

With a known repeater, a facility like the Very Large Array near Socorro, N.M., could stare at the same patch of sky, wait for the next eruption and identify the host galaxy (SN Online: 2/26/16). “It’s a wake-up call that there’s a lot we can do with existing FRBs,” Lorimer says.

27
A recently claimed home for an elusive cosmic radio burst might not be the host galaxy after all. What appeared to be an afterglow from the eruption might instead have been a run-of-the-mill radio emission from an unrelated galaxy, researchers claim online February 28 at arXiv.org.

Fast radio bursts, ephemeral blasts of radio waves that appear to originate in other galaxies, have been stumping astronomers since 2007 (SN: 8/9/14, p. 22). Identifying a host galaxy for an FRB could provide a clue to its cause. A recent FRB seemed to finally leave a return address (SN Online: 2/24/16). Two hours after the initial detection, astronomers caught a fading radio signal coming from the same direction. That signal led a team headed by Evan Keane, an astronomer with the Square Kilometer Array Organization in Macclesfield, England, to a galaxy about 6 billion light-years away.

But the claimed afterglow might have nothing to do with the FRB, Harvard University astronomers Peter Williams and Edo Berger suggest. A supermassive black hole appears to live in that galaxy, and it is actively feeding off a swirling disk of interstellar detritus. Such cosmic snacks routinely belch out radio waves. Observations of the galaxy obtained on February 26 and 27 at the Very Large Array in New Mexico show that not only has the “afterglow” returned, but it is brighter than what researchers saw in the hours after the FRB detection.

Williams and Berger argue that the galaxy is not the home of the FRB. But Duncan Lorimer, an astrophysicist at West Virginia University in Morgantown, says “I would be cautious about dismissing the result.” Astronomers don’t know what causes FRBs and many mysteries remain. One burst detected in 2012, for example, recently became the first FRB known to repeat itself after erupting 10 more times last year (SN Online: 3/2/16). It’s possible that this one repeats as well, Lorimer says. “It tells us how little we still know.”

Keane and colleagues are performing additional studies to better understand what’s going on. “When we've completed and fully considered those, we will certainly report our findings,” he says. “I know that FRBs are exciting, and appreciate that there is a lot interest, but we really can't rush the scientific process.”

28
Faculty Sections / Psychology’s replication crisis sparks new debate
« on: March 09, 2016, 12:03:56 PM »
Psychology got rocked last year by a report that many of the field’s published results vanish in repeat experiments. But that disturbing study sounded a false alarm, a controversial analysis finds.

The original investigation of 100 studies contained key errors, contend Harvard University psychologist Daniel Gilbert and his colleagues. After correcting for those errors, the effects reported in 85 of those studies appeared in replications conducted by different researchers. So an initial conclusion that only 35 studies generated repeatable findings was a gross underestimate, Gilbert’s team reports in the March 4 Science.

“There’s no evidence for a replication crisis in psychology,” Gilbert says.

Psychologist Brian Nosek of the University of Virginia in Charlottesville and other members of the group who conducted the original replication study (SN: 10/3/15, p. 8) reject Gilbert’s analysis. The 2015 report provides “initial, not definitive evidence” that psychology has a reproducibility problem, they write in a response published in the same issue of Science.

Strikingly, “the very best scientists cannot really agree on what the results of the most important paper in the recent history of psychology mean,” says Stanford University epidemiologist John Ioannidis. Researchers’ assumptions and expectations can influence their take on any results, “no matter how clear and strong they are.”

Many repeat studies in the 2015 paper differed dramatically from initial studies, stacking the deck against achieving successful replications, Gilbert says. Replications often sampled different populations, such as substituting native Italians for Americans in a study of attitudes toward black Americans. Many altered procedures. One replication effort gave older children the relatively easy task of locating items on a small computer screen, whereas the original study gave younger children a harder task of locating items on a large computer screen.

Repeat studies also generally included too few volunteers to make a statistically compelling case that a replication had succeeded or failed, Gilbert says. Another problem was that each original study was replicated only once. Multiple repeats of a study balance out differences in study procedures and increase the number of successful replications, the scientists argue.

In a replication study that often amounted to a comparison of apples and oranges, at least 34 replication studies should have failed by chance, assuming all 100 original studies described true effects, Gilbert and his colleagues estimate. That makes the new estimate of 85 successful replications even more impressive, they say.

Nosek’s group calculates that only about 22 replication attempts in the 2015 study should have failed by chance. Tellingly, Nosek says, even successful replications found weaker statistical effects than the original studies had. Published studies make statistically significant findings look unduly strong, he says. Journals usually don’t publish replication failures and many researchers simply file them away.

Another new analysis of Nosek’s group’s work suggests that replication study samples need to be beefed up before any conclusions can be made about the durability of psychology results. Failures to replicate in the 2015 investigation largely occurred because many original studies contained only enough participants to generate weak but statistically significant effects, two psychologists assert February 26 in PLOS ONE. Journals’ bias for publishing only positive results also contributed to replication failures, add  Alexander Etz, at the University of Amsterdam at the time of the study, and Joachim Vandekerckhove of the University of California, Irvine.

The pair statistically analyzed 72 papers and replication attempts from Nosek’s project. Only 19 original studies contained enough volunteers to yield a strong, statistically significant effect. Nosek’s team needed many more studies with comparably large sample sizes to generalize about the state of replication in psychology, the researchers say.

Researchers in psychology and other fields need to worry less about reproducing statistically significant results and more about developing theories that can be tested with a variety of statistical approaches, argues psychologist Gerd Gigerenzer of the Max Planck Institute for Human Development in Berlin. Statistical significance expresses the probability of observing a relationship between two variables — say, a link between a change in the wording of a charitable appeal and an increase in donations — assuming from the start that no such relationship actually exists. But researchers rarely test any proposed explanations for statistically significant results.

Pressures to publish encourage researchers to tweak what they’re studying and how they measure it to ensure statistically significant results, Gigerenzer adds. Journals need to review study proposals before any experiments are run, in order to discourage such “borderline cheating,” he recommends.

29
Faculty Sections / Missing genes not always a problem for people
« on: March 09, 2016, 12:03:20 PM »
Many genes may be dispensable.

Each of 3,222 British people with Pakistani heritage carries, on average, mutations in 140 genes that stop those genes from working, researchers report online March 3 in Science. Examination of those people’s exomes, the small portion of the genome that encodes proteins, revealed that among a subset of 821 participants, a total of 781 genes were rendered obsolete by “loss-of-function” mutations. Those genes include 422 that scientists didn’t know people could live without and still be healthy.

Previous studies had indicated that some genes are commonly missing in healthy people. The new study suggests that even rare mutations that disable both copies of a gene, which scientists thought would be associated with diseases, aren’t necessarily a problem.

Researchers in England and the United States compared health records of 638 people in the study who have rare mutations that abolish both copies of one or more genes with records from 1,524 people without the rare mutations. Those with rare mutations were no more likely to have health issues than those without, the researchers found.

Even really important genes may go missing with no harm. One woman had mutations in the PRDM9 gene, which is important during the formation of eggs and sperm. Without the mouse version of the gene, mice are sterile. Dogs have a fallback mechanism to compensate for losing the gene. The woman had a child, indicating that she is fertile, so humans must have a way to compensate for the missing gene, too — though it appears to be different than dogs’.

Compensatory mechanisms could complicate the search for genes responsible for rare genetic diseases, the researchers say.

30
At last Science News is able — thanks to novelist Amy Tan — to illuminate a question nagging readers (and often writers) of stories about new species named in honor of celebrities. When someone names a slime-mold beetle or a leech after you and you say you’re honored — really?

Tan (whose novels include The Joy Luck Club and The Valley of Amazement) swiftly supplied a vivid answer to our question about whether “thrilled” was the word to describe her feelings about a January Zoologica Scripta paper naming a small, blood-sucking leech in her honor.

She felt a connection with that particular leech, she writes in an e-mail. Before she knew it would bear her name, she had happened upon the blog written about 10 years ago by researchers looking for leeches, preferably new species, in the rainforests of Australia. “Blood Lust II” was the expedition name used by Mark Siddall, a curator at the American Museum of Natural History and his fellow leech-seekers.

“They described conditions of sweat, mosquitoes, humidity and unwashed clothing,” Tan reminisces. She shared the blog entry for the expedition’s second-to-last day, when the scientists reached an area devastated by Cyclone Larry:

 “We're speechless.

There's so little left.

Like a bomb went off.

…Trees, regardless of size, lie twisted and snapped like matchsticks... Worse, the canopy is gone. …Gone. Like a lawnmower came by and simply hacked off the upper layer of the rainforest.

…On the positive side, we're sure we have a new species.”

Tan comments: “That’s how you do science — by mucking about in a vast rainforest with both beautiful and unpleasant conditions, all the while being attuned to the smallest details that make up what we mean by uniqueness.”


Novelist Amy Tan was quoted in a press release as saying she was "thrilled" about having a leech as a namesake. In an e-mail to Science News, she elaborates.
© WENN LTD/ALAMY STOCK PHOTO
The leech, Tan writes, was a “consolation prize,” and she remembered it when she heard years later that the forest-dwelling species would be named Chtonobdella tanae. She knows the explorers and has let one of their lab leeches stroll on her skin (which it did not bite).  In the scientific paper officially christening Tan’s namesake, Siddall and his coauthors thank Tan for her support and her companionship on nature explorations and note that her book Saving Fish from Drowning mentions terrestrial leeches three times.

“I spent quite a bit of time reading the paper, and in doing so, I learned a few useful words, like annulate, epididymal, gonopore, and nephridial,” Tan writes. “I already knew the words “seminal” and “receptacle” but until then, I had not had the occasion to use them together during dinner conversations. I have since then.”

Tan went further, out-sciencing by far most news accounts of her namesake leech by actually describing its features (though without using epididymal or nephridial even once).

The first clue to its uniqueness, she notes, were the four rings on each body segment instead of the five normal for the known leeches of the area. It’s a hermaphrodite like other leeches but with some uniquely placed male organs. “I know that its jaw is positioned differently, as are its five pairs of eyes, and that the digestive tract has some neat features as well.” (As paper coauthor Michael Tessler explains, the end of the digestive tract “is twisty and turny and doubles back on itself,” unsurprising for humans, but startling in a leech.)

Tan adds, “I do know that it is not simply the leech that is special in its own right; it is also the way in which it was thoroughly identified.” C. tanae, only a few squishy millimeters wide, would have been a challenge to dissect without distorting internal organs, so the scientists developed ways to prepare a specimen so CT scans highlighted subtleties of its innards. “It's a method that will be used with many specimens, maybe even those from a hundred years ago,” Tan writes.


She signs off by adding, “That's the long answer to: Am I thrilled that this leech bears my name?

“You bet.”

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