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چهارشنبه 13 اردیبهشت 1391

Killer whales are expert vocal mimics

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Killer whales are expert vocal mimics

 

VANCOUVER, British Columbia (UPI) -- Killer whales in Canadian waters are vocal expert mimics and can impersonate calls from another whale clan or group with a different dialect, researchers say

Wild orcas near Vancouver Island in British Columbia have been found to mimic calls from other groups even when members of that group aren't around, AAAS ScienceMag.org reported

Behavioral biologist Brigitte Weiss of the University of Vienna says the calls seem to resemble the calls of foreign groups that the original group may have mingled with to mate or cement alliances

The whales could have multiple uses for the imitation, such as labeling outsiders or keeping tabs on their location, she says

"Mimicking another group's calls could be a way of referring to that group ... or of communicating something about that group to one's own family members," she says

Or, Weiss acknowledges, it's equally possible the mimicry has no function at all

 

ArcaMax Science & Technology Ezine


چهارشنبه 13 اردیبهشت 1391

Sounds may predict avalanches

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Sounds may predict avalanches

 

GENEVA, Switzerland (UPI) -- Forecasting avalanches may be possible by listening for increases of icequakes and their distinctive sounds, Swiss researchers say

Geologists listening in on the groan and creak of icequakes -- cracking inside frozen soil or rock containing water or ice -- have developed a model that can predict a collapse up to 15 days before it happens, ScienceNews.org reported Friday

To find early warning signs of an avalanche, scientists in Switzerland placed seismic instruments on a glacier on the northeast face of the Weisshorn, a mountain in the Swiss Alps that towers over the village of Randa, 8,200 feet below. Avalanches on the Weisshorn have claimed 51 lives since the 17th century

In 2003 researchers froze a special microphone called a geophone into the glacier to pick up seismic vibrations

Two weeks before the glacier split in 2005, researchers detected changes in the sounds picked up by the microphone

"As you approach rupture, you hear more sounds," geologist Jerome Faillettaz says. "It's just like if you break a pen or a cracker. You hear some small noise before it breaks"

By combining observations of a glacier's slow movement with the sounds of the icequakes, the researchers say they can detect a rupture 15 days in advance

ArcaMax Science & Technology Ezine


چهارشنبه 13 اردیبهشت 1391

World running out of fishing room

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World running out of fishing room

 

VANCOUVER, British Columbia (UPI) -- Earth has run out of room to expand world fisheries and maintaining the present supply of wild fish is unsustainable, a Canadian study says

University of British Columbia researchers say fisheries expanded at a rate of almost 400,000 square miles per year from the 1950s to the end of the 1970s, and then the rate of expansion more than tripled in the 1980s and early 1990s before experiencing a decline, ScienceDaily.com reported Friday

"The decline of spatial expansion since the mid-1990s is not a reflection of successful conservation efforts but rather an indication that we've simply run out of room to expand fisheries," study author Wilf Swartz of the UBC Fisheries Center says

A peak catch of 90 million tons in the late 1980s dropped to 87 million tons in 2005, the study says

"If people in Japan, Europe, and North America find themselves wondering how the markets are still filled with seafood, it's in part because spatial expansion and trade makes up for overfishing and 'fishing down the food chain' in local waters," Swartz says

But it's a situation that cannot continue, another researcher says

"The era of great expansion has come to an end, and maintaining the current supply of wild fish sustainably is not possible," study co-author Enric Sala says. "The sooner we come to grips with it -- similar to how society has recognized the effects of climate change -- the sooner we can stop the downward spiral by creating stricter fisheries regulations and more marine reserves

 

ArcaMax Science & Technology Ezine 


چهارشنبه 13 اردیبهشت 1391

Hummingbirds all 'a-flutter' in mating

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Hummingbirds all 'a-flutter' in mating

 

 

NEW HAVEN, Conn. (UPI) -- Males of some hummingbird species create loud sounds during mating displays by using their tail feathers as they "dive-bomb" past females, U.S. researchers say

Scientists at Yale University discovered males produce the loud sounds as the air flows past the tail feathers in the dive, causing them to flutter, a National Science Foundation release said Thursday

When the courting male bird reaches the lowest point of his dive, which can begin anywhere from 5 to 40 yards above a perched female, he rapidly spreads and then closes his tail feathers, causing them to flutter and generate sound

Yale researcher Christopher Clark says males of different hummingbird species all have their own signature sound. The size, shape, mass and stiffness of the hummingbird's feathers create the tone of each species' particular sound, he said

"The sounds that hummingbird feathers can make are more varied than I expected
 
 


چهارشنبه 13 اردیبهشت 1391

Study finds men inclined to be fathers

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Study finds men inclined to be fathers

 

EVANSTON, Ill. (UPI) -- A Northwestern University study shows that fathers, like mothers, are naturally inclined to take care of their children

The study, to be published Monday, found testosterone levels in men sharply decline when they become fathers, the Chicago Sun-Times reported

The reduction of testosterone can steer males away from competing for a mate and towards spending more time on the responsibilities of fatherhood, the study says

"Raising human offspring is such an effort that it is cooperative by necessity, and our study shows that human fathers are biologically wired to help with the job," said Christopher Kuzawa, who co-authored the study with Ph.D. student Lee Gettler

The study followed 624 childless men in the Philippines in their early 20s into fatherhood

Gettler said he and Kuzawa found "the men who started with high testosterone were more likely to become fathers." Then, after their children were born, "their testosterone went down substantially"

 

Science & Technology by ArcaMax



شنبه 26 فروردین 1391

New pump made for infant heart surgery

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New pump made for infant heart surgery

 

WEST LAFAYETTE, Ind. (UPI) -- U.S. researchers say they've developed a new heart pump that could help infants born with congenital heart defects survive necessary surgeries

Scientists at Purdue University have created a "viscous impeller pump" for children born with univentricular circulation, a congenital heart disease that is the leading cause of death from birth defects in the first year of a child's life, a university release said Tuesday

The normal human heart contains two pumping chambers, called ventricles

One circulates oxygenated blood throughout the body, while the other less-powerful ventricle circulates deoxygenated blood to the lungs

Children born with univentricular circulation have only one functioning ventricle but can survive if blood vessels in the heart are restructured in a series of open-heart surgeries

At least 30 percent of babies do not survive the surgeries, called the Fontan procedures

To improve the survival rate, Purdue engineers and researchers developed the new mechanical pump to assist the heart during surgeries

"A big advantage of this pump is that it gets delivered through the skin with a catheter without open heart surgery," Steven Frankel, a Purdue University professor of mechanical engineering, said

"It is designed to be in the body for two weeks at most, almost like a disposable item," Frankel said

The researchers have received a $2.1 million, four-year grant from the National Institutes of Health's National Heart, Lung and Blood Institute to continue developing the heart pump, Purdue said

 

ArcaMax Science & Technology Ezine


 


شنبه 26 فروردین 1391

Study: Jet lag may mean brain lag

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Study: Jet lag may mean brain lag

 

BERKELEY, Calif. (UPI) -- Jet lag might make you more than just groggy and dazed, U.S. researchers say -- it might even make you stupid

Researchers at the University of California, Berkeley, said hamsters suffering extreme, chronic jet lag had about half the normal rate of new neuron birth in one part of the brain and showed deficits in learning and memory,
ScienceNews.org reported Tuesday

The scientists subjected hamsters to simulated jet lag by advancing their day and night schedule by 6 hours every three days for nearly a month, "like a flight from New York to Paris every three days," study coauthor Erin Gibson said

Jet lag decreases the numbers of new neurons being created in the hippocampus by about 50 percent, the team found, as mental function suffred

Even after 28 days of a back-to-normal schedule, the formerly jet-lagged hamsters still showed learning and memory problems, Gibson said

The mismatch between the internal body clock and the external environment "is having a long-term effect on learning and memory," Gibson said

While it's not certain exactly how these cognitive problems are induced by jet lag, the sleep hormone melatonin, stress and increased cell death are all possible culprits that need to be explored, she said

 

ArcaMax Science & Technology Ezine



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