Bioluminescence lights up the oceans

Mysteries still surround glow-in-the-dark creatures

The definition of bioluminescence "is easier than the pronunciation and spelling of the word: It is just visible light made by living animals," says Edith Widder, president of the Ocean Research and Conservation Association in Fort Pierce, Fla.
 
The word may be easy to define, but the chemical process is still poorly understood. Bioluminescence has apparently evolved independently at least 40 times in species belonging to more than 700 genera, or classifications of organisms. Widder notes in the journal Science that about 80 percent of those genera are found in the open ocean.
 

Examples of bioluminescent organisms include yellow-glowing Tompteris worms (upper left). Also pictured (clockwise) are the squid Abralia veranyi; northern krill, known by the scientific name Meganyctiphanes norvegica; the scaleless black dragon fish (Melanstomias bartonbeani); and deep-sea jellyfish (Atolla wyvillei).  

 

Spiders devour ants front-end first

Animal eating patterns involve complicated balancing of quantity vs. quality

A spider that only eats ants is choosy about which body parts of its prey it devours based on their nutritional value.

These new findings are the first to demonstrate that "specialist" predators relying on a single food source might have evolved feeding behaviors to maximize what they get out of meal time, the researchers say.

"We found that these spiders do have to balance their nutrient intake by choosing different body parts of their exclusive ant prey," said Stano Pekár, an assistant professor of ecology and zoology at Masaryk University in the Czech Republic and lead author of the research published in the April 15 issue of the journal Animal Behaviour. 

When chowing down on ants, the spiders consistently began with the protein-packed front parts before getting to the fattier hind segment, called a gaster or abdomen. The picky eating seemed to pay off: Spiders reared on just front-end ant pieces grew faster, bigger and lived longer than those served only gasters or even whole ants.

Yet when given the option, spiders still gobbled on the gaster rather than shunning it entirely for the front parts, hinting that the gaster contains vital nutrients not found elsewhere in the ant's body.

Feasting on ants
For the experiments, the researchers collected dozens of Zodarion rubidum, an ant-eating spider species found in Europe and the United States that has a light orange head and legs.

These spiders attack ants and inject them with powerful venom that paralyzes the prey in mere minutes.

When settling in for an ant banquet, Zodarion spiders puncture the insects' hard exoskeletons with fangs and inject enzymes that "liquefy the inner tissues," Pekár said. The spiders slurp out this mush before moving to different areas of the carcass. These spider eating sessions last from two to four hours.

To see how well the spiders lived on particular pieces of an ant, the researchers divided 60 of the arachnids into three dining clubs that were given the ants' front end (head, legs and thorax or mid-body), gasters or whole ants. Each group received a similar portion of fresh ant flesh by weight.

The spiders given only gasters fared poorly: All 20 died within six weeks of the start of the experiment, whereas eight of the spiders dining on front parts and three on whole ants were still alive and kicking at the experiment's end three months later.

When alive, the spiders kept on the gaster-only diet initially grew but then shriveled, while those eating the head, legs and thoraces thrived, with some tripling their weight. The spiders devouring entire ants also did well, but did not develop as fast or get as big as the front-end eaters.

The choicer parts of an ant To find out whether the spiders had ant-part preferences, the researchers gave 48 spiders small, medium or large whole ants. 

"When we provided [spiders] access to the entire prey, they responded by consistently choosing to feed first and mostly on the head and thorax," Pekár and his co-authors wrote.

Even when given gigantic ants that provided more than enough sustenance in the front-end parts alone, nearly all of the spiders spent at least an hour munching on the fatty ant derrieres.

"We thought maybe the spiders could live only on the protein" found up front, Pekár said, but after working over the thoraces and legs, the hungry spiders "always went for the gaster." This behavior implies that the gaster contains some essential nutrients not found elsewhere in the ant, but that protein is the priority.

While spiders given the protein-rich regimen fared best in the experiment, Pekár suspects those with a more well-rounded diet would ultimately do better. Having sucked out all they could from the front parts, the spiders with a whole ant might have over-gorged on the leftover gasters and done themselves a nutritional disservice during the short experiment, Pekár said.

Eating right also a hunters' burden
The findings jibe with the emerging view that for predators, achieving proper nutrition is trickier than simply finding enough prey to eat.

And what's true for persnickety spiders might also apply to nature's big, "generalist" carnivores.

As for why cheetahs eat particular portions of a gazelle, for example, the thinking had been that the "cheetah did not consume the entire gazelle, because he was stuffed by half of it," Pekár told LiveScience. "But now we see that this is not the full truth. The cheetah did not consume some muscles of the gazelle because he was [already] stuffed with proteins, for example."

Overall, animals' eating patterns involve a complicated balancing of quantity versus quality.

"Nutrition is one of the most important things that animals do," said David Raubenheimer, a professor of nutritional ecology at Massey University in Auckland, New Zealand who has not involved in the study. "I would expect them to evolve the ability to capitalize on any opportunity they have for getting the best they can."

 

First birds were poor fliers

Experts say feathers weren’t strong enough to flap

The earliest birds did not have strong enough feathers to take to the air by flapping their wings and were gliders at best, researchers said Thursday.

While modern birds have feathers with a strong central shaft that is hollow to reduce weight, the earliest-known bird Archaeopteryx and another ancient ancestor had feathers that were much thinner and weaker.

Robert Nudds of the University of Manchester and Gareth Dykearchaeoptery of University College Dublin calculated in a report in the Friday issue ofl Science that even if their feather shafts were solid, they would still have been barely strong enough to allow gliding.

Archaeopteryx lived in the late Jurassic period, about 140 million years ago, and Confuciusornis in the early Cretaceous, around 100 million years ago.

It is widely believed among paleontologists that the first birds arose from small, feathered dinosaurs.

One theory is that birds evolved from small dinosaurs living in trees that initially used feathers to control their descent like a parachute, then glided through the forest canopy and eventually flapped their wings to achieve true flight.

"Some thrust generation by these fossil birds cannot be discounted, but the vigorous flapping flight of modern birds is highly unlikely," the researchers concluded.

Nudds said poor flight ability suggests that the early birds lived in trees and would launch in order to glide to another tree. If they landed on the ground they could clamber back up to gain height for their next glide.

"If Archaeopteryx and Confuciusornis were arboreal dwellers, which is suggested by my data, then it also suggests that avian flight originated in the trees and not on the ground," he said.

"Fossil wings that superficially resemble those of existing birds don't necessarily indicate flapping flight ability," concluded Nudds, who added that the origin of avian flapping flight is likely to be more recent than previously thought.

 

5 minutes in the green can boost mood

Outdoor exercise improves mental health, study finds

Just five minutes of exercise a day in the great outdoors can improve mental health, according to a study released on Saturday, and policymakers should encourage more people to spend time in parks and gardens.

Researchers from the University of Essex found that as little as five minutes of a "green activity" such as walking, gardening, cycling or farming can boost mood and self esteem.

"We believe that there would be a large potential benefit to individuals, society and to the costs of the health service if all groups of people were to self-medicate more with green exercise," Barton said in a statement about the study, which was published in the journal Environmental Science & Technology.

Many studies have shown that outdoor exercise can reduce the risk of mental illness and improve a sense of well-being, but Jules Pretty and Jo Barton, who led this study, said that until now no one knew how much time needed to be spent on green exercise for the benefits to show.

Barton and Pretty looked at data from 1,252 people of different ages, genders and mental health status taken from 10 existing studies in Britain.

They analyzed activities such as walking, gardening, cycling, fishing, boating, horse-riding and farming.

They found that the greatest health changes occurred in the young and the mentally ill, although people of all ages and social groups benefited. The largest positive effect on self-esteem came from a five-minute dose of "green exercise."

All natural environments were beneficial, including parks in towns or cities, they said, but green areas with water appeared to have a more positive effect.

 

Chicken nuggets put to the test: taste vs. health

Consumer Reports warns kiddie favorite is loaded with salt, fat

Consumer Reports put chicken nuggets to the test and found many brands are loaded with salt and fat.

After evaluating 14 supermarket brands of refrigerated and frozen chicken nuggets — including two chicken-like nuggets made from soy — Consumer Reports Health said that choosing a healthier nugget will mean sacrificing flavor.

While none of the 14 brands received a "poor" nutritional rating from the health website, which is associated with Consumer Reports magazine, the only brand to get a "very good" nutrition rating — Health is Wealth — didn't get high marks in taste.

The site also urged consumers not to be misled by brands that are advertised as natural or organic, terms that aren't necessarily indicators of nutritious foods.

For instance, Consumer Reports said that while Tyson accurately claims its chicken nuggets are "100 percent all natural," one serving (about 3 to 4 ounces) of its nuggets has 270 calories, 17 grams of fat and 470 milligrams of sodium.

It's generally recommended that people consume fewer than 65 grams of fat and 2,300 milligrams a sodium a day.

Consumer Reports gave Tyson's nuggets a "fair" rating for nutrition.

"Whatever the claims that are being made, you definitely want to turn to the nutritional panel on the product and see if it matches what you're looking for," said Gayle Williams, deputy editor of Consumer Reports Health.Oliver pushed nuggets into the news recently when he made them on his ABC reality program, "Jamie Oliver's Food Revolution." He thought the process of grinding up the chicken parts would gross out the children he made them for, but they ate them eagerly.

Of the 14 items tested, only Health is Wealth received a "very good" nutritional rating, with 130 calories, 4 grams of fat and 230 milligrams of sodium. Testers, however, didn't care for the taste.

"There's the rub. The brand may be more nutritious than others, but if your kids won't eat it, what good is it?" said Williams.

On taste, three brands earned a "very good" rating: Market Pantry (from Target, which told the magazine it was changing its formulation), Bell & Evans Breaded and Kirkland Signature Disney (Costco). Each received a "good" nutritional rating.

And McDonald's nuggets? The site asked children to compare them against the others. McDonald's came out on top, but earned only a "fair" nutrition rating.

 

Folic acid doesn’t cut risk of stroke, study finds

In the U.S., any health benefits already achieved via food fortification 

Studies have linked low blood levels of a chemical lowered by folic acid to reduced rates of stroke. However, folic acid supplements don't seem to prevent strokes, according to a review of clinical trials involving more than 39,000 participants.

"We do not have evidence that would warrant boosting folic acid supplementation for stroke reduction," researcher Dr. Jeffrey Saver told Reuters Health.

Saver and colleagues at the UCLA Stroke Center in Los Angeles identified 13 well-designed clinical trials of folic acid and stroke. Participants in all the trials had been diagnosed with conditions such as kidney and heart disease, as well as stroke.

There were 784 strokes among 20,415 participants taking folic acid, compared to 791 strokes reported among 18,590 people who did not take the supplements.

The analysis, in the American Heart Association's journal Stroke, settles the question about whether folic acid supplementation leads to a major reduction in stroke, Saver said.

"The answer is 'no,'" Saver said.

Still, the researchers suggest more research into folic acid and stroke, particularly for men and those in the earliest stages of heart disease. Data from both of those groups suggested there might be an effect, although researchers could not determine whether or not that was due to chance.

Those potential benefits appeared in trials carried out in countries whose food supplies were not fortified with folic acid. In the U.S., the benefits of folic acid supplementation may have already been achieved through food fortification, Saver noted. In an effort to reduce the birth defect spina bifida, the U.S. Food and Drug Administration required the addition of folic acid to all enriched cereal-grain foods starting in 1998.

"Extra pills don't make that much additional difference," Saver said.

 

More kids eat dinner from Uncle Sam

13 states, plus D.C., provide after-school supper programs

BRATTLEBORO, Vt. - While the other preschoolers were warming up to the vegetable pesto lasagna, 3-year-old Avery Bennett dove in with no hesitation.

"Can I have some more lasagna?" Bennett said from her booster seat. "I love it."

She moved on to her seconds, and the other kids at the evening care program in Brattleboro were also chomping down the dish made of spinach, peppers, carrots, tomato, fresh basil and cheese.

More low-income school kids could soon have access to free nutritious dinners like the lasagna that Avery loved. A U.S. Department of Agriculture program in Vermont, 12 other states and the District of Columbia provides reimbursements for the suppers, served at after-school programs for at-risk kids in communities where at least 50 percent of households fall below the poverty level.

"What it allows us to do is provide those kids with an extra nutritious meal before they go home because some kids go home to nothing," said Susan Eckes, director of child nutrition programs for the Food Bank of Northern Nevada in McCarran, Nev.

Around the country, about 49,000 children benefit from the after-school meals each day. The program is expected to cost a total of $8 million from 2009 to 2013, the USDA said.

With more families losing jobs and homes, the need is growing, officials said.

The number of Americans who live in food-insecure households — which at times don't have enough nutritious food — rose from 36 million people in 2007 to 49 million in 2008, according to the most recent report from USDA's Economic Research Service.

Among those, 16.7 million were children, up from 12.4 million in 2007.

Nearly one in four children in the U.S. are food insecure and about one in five live in poverty, according to a report from Feeding America, a network of 200 food banks around the country.

"As the economy gets worse, we're seeing more and more kids," said Beth Baldwin-Page, executive director of the Boys & Girls Club of Brattleboro.

In East Prairie, Mo., kids who may have skipped the meal from time to time are coming every day, said Lester Gillespie, youth program director at the Susanna Wesley Family Learning Center, which serves 150 meals a day at two sites to kids age 5 to 18.

A lack of nutritious food, especially in the first three to five years, can have lasting effects on the health and development of children. Filling their stomachs with nutritional meals helps them learn and concentrate, officials have said.

"What we've noticed is that when kids are eating nutritional meals, they tend not to get involved in negative activities such as doing graffiti or committing delinquent acts because when their stomach is full they make good decisions," said Gillespie.

Programs in Connecticut, Delaware, Illinois, Maryland, Michigan, Missouri, Nevada, New York, Oregon, Pennsylvania, West Virginia, Wisconsin, the District of Columbia and now in Vermont are eligible for reimbursement for suppers.

The USDA requires the sites to offer nutritionally balanced suppers with milk, a protein, fruit, vegetables and bread or a grain item.

Delaware, where the supper program is one of the fastest-growing child nutrition programs in the state, has gone a step further, prohibiting the use of any grain product that contains more than 6 grams of sugar or any product where more than 35 percent of calories are derived from fat.

The Brattleboro Boys & Girls Club started offering dinners on its own two and a half years ago. When it learned the supper program was being expanded to Vermont, it applied for and just starting getting the federal reimbursement of $2.68 per meal.

Three days a week, the club offers dinners feeding 40 to 60 kids on a Thursday night to up to 100 on Friday.

"It's popular. Unfortunately, it's necessary," said Ricky Davidson, unit director.

"We see families getting evicted left and right. They don't have a place to live, let alone cook food," Baldwin-Page said.

Bernie Parent, 18, of Brattleboro has relied on the meals since he and his mother became homeless last year.

Now living on his own in an apartment, going to high school, and working at the Boys & Girls Club, he still relies on the three free dinners each week.

"It helps out a lot," he said.

 

Being a supertaster is no piece of cake

Being a “supertaster” may sound like a foodie’s dream come true, but in reality, it’s no picnic.

Coffee and alcohol are unpalatable – along with tomatoes, Parmesan cheese, strawberries, condiments and most sweets.

“I can’t stand cake,” says Michelle Triplett, a 31-year-old stay-at-home mom and supertaster from Olympia, Wash., who spoke, coincidentally, on her birthday.  “It’s too sweet for me. And when I drink beer, I gag. It’s like drinking urine.”

Supertasters detect components – like salt or bitterness -- in food that others can’t, says Dr. Alan Hirsch, founder and neurological director of the Smell & Taste Treatment and Research Foundation in Chicago.

“[Supertasters] have densities of taste buds that are 10 to 100 times greater than the normal population,” he says. “As a result, supertasters are much more sensitive to spicy foods and they can taste … very mild flavors.”

Triplett, whose favorite meals are turkey sandwiches and macaroni and cheese, says the blander the better, since most everything else is, as They Might Be Giants put it in their song “John Lee Supertaster,” simply “too much.” 

The condition is genetic, tends to affect women more than men and affects 25 percent of the U.S. population; non-tasters (people with a reduced ability to taste) make up another 25 percent with the rest of the population described as medium or normal tasters.

While there are some benefits -- supertasters tend to avoid sugars, salts and fats, so they suffer less from obesity and cardiovascular disease – there’s a potential downside. Supertasters often avoid green vegetables because of their bitter taste, so they miss out on cancer-fighting flavanoids and other nutrients.

 “Many vegetables have bitterness in them -- like green pepper – so a supertaster may avoid [them],” says Hirsch.  Other problem veggies include broccoli, Brussels sprouts, cabbage, kale, olives and spinach.

 “When I get Brussels sprouts on my tongue, I immediately want to pull that whole patch of tongue off,” says Triplett. Tomato-based foods, apples and blueberries are also too potent for her.

Supertasters are also more prone to burning mouth syndrome, a condition in which a person’s tongue or mouth feels like it’s on fire.

“It’s horribly disabling,” says Hirsch. “You can’t eat food, you can only drink water and it can be quite painful.

If you think you’re a supertaster, a five-minute survey developed by Cornell University can help. There’s also a home test involving blue food coloring. Or a simple taste test – available for a small fee -- that uses a filter paper impregnated with a chemical known 6-n-propylthiouracil (PROP).  Non-tasters won’t taste anything on the paper; medium tasters will taste a small amount of bitterness. Supertasters, however, will find the chemical “stomach-wrenchingly bitter.”  

Fisherman's find: rare, 12-foot-long creature

Giant Oarfish was last seen 130 years ago off Swedish coast

STOCKHOLM - First he thought it was a piece of plastic floating near the shoreline. When he got closer, 73-year-old Kurt Ove Eriksson realized the 12-foot serpent-like object was a rare creature from the depths of the ocean.

Marine biologists later determined Eriksson had found a Giant Oarfish — the world's largest bony fish — last seen in Swedish waters about 130 years ago.

"It was very long and shiny," Eriksson told The Associated Press on Wednesday. "It also had whiskers, even though it looked like they had been broken off. And a strange light-pink dorsal fin."

A retired engineer and avid fisherman, Eriksson made the unusual discovery Saturday on his way to his boathouse in Bovallstrand, on Sweden's west coast.

"I've been fishing around here since 1957 and I've never seen anything like it," he said. "But I've seen enough fish to know that it was a deep-water fish."

Eriksson handed over the dead fish to The House of the Sea, an aquarium in the nearby town of Lysekil, where marine expert Roger Jansson said it's being kept pending a decision on what to do with it.

Jansson said the Giant Oarfish can grow up to 36 feet, and is believed to live in deep waters. He said the last recorded discovery in Sweden was in 1879.

Sightings of the fish are believed to have inspired tales of sea serpents.

 

Whoa! Eating tomatoes helps prevent sunburn?

Prevention magazine identifies myths and facts about skin care, treatments

With such an abundance of health-related information and oft-repeated advice out there, which tidbits are mere myths and which are actual facts? Here, Prevention magazine provides clarity about common questions related to skin and skin care.

Myth or fact? The way your skin ages is largely determined by your genetics.
MYTH. A recent study that analyzed identical twins found that your lifestyle significantly trumps your DNA when it comes to facial aging. Experts estimate that daily habits account for up to 80 percent of the changes in appearance that occur over time. The good news is that with a few precautions, like wearing an SPF 30 sunscreen every day, you can look vibrant and youthful no matter how many candles are on your birthday cake.

Myth or fact? High stress levels can cause your skin to age more quickly.
FACT. Emotional upheavals can make your skin look five years older than your chronological age. Constant anxiety increases the stress hormone cortisol, which causes inflammation that breaks down collagen. It also triggers a chain of responses that can lead to facial redness and acne flare-ups. Try to exercise and meditate a little every day, which have been shown to lower stress-hormone levels. To quell inflammation, eat antioxidant-rich foods such as berries, oranges and asparagus. 

Myth or fact? All babies are born without freckles.
FACT. Babies, of course, can be born with birthmarks and "beauty marks," but it's true that upon entering the world they have no freckles, which the skin produces (using excess pigment) in response to sun exposure. As babies get out in the sun, those with fair complexions and light eyes will be especially prone to developing freckles (and will have a higher likelihood of skin cancer and melanoma later in life). Those freckles on the redheaded kid's cheeks aren't cute — they're sun damage! And freckles probably also indicate damage to the DNA in your skin cells. Children and adults alike should have their freckles monitored regularly by a dermatologist and vigilantly use sunscreen of SPF 30 or higher.

Myth or fact? The most important time to wash your face is when you first wake up in the morning.
MYTH. The most important time to wash your face is before you head to bed. Dirt, bacteria and makeup left on overnight can irritate skin, clog pores and trigger breakouts. Remove this top layer of grime with a gentle face wash (skin should feel pleasantly tight for 10 to 15 minutes post-cleansing), which also allows anti-agers to penetrate deeper for better results. Because oil production dips with hormonal changes in your 40s, cleansing twice daily can dry out your complexion and make wrinkles look more pronounced. To refresh skin in the morning, splash with lukewarm water.

Myth or fact? Drink more water if you have dry skin.
MYTH. Unless you're severely dehydrated, the amount of water you consume has no effect on how dry your skin is. Overhydrating may even take a toll on skin by flushing electrolytes out of your bloodstream. Aim to meet the Institute of Medicine of the National Academies recommendation to consume 91 ounces of fluid a day (around 11 cups). Remember, choosing food (like fruits and veggies) with a high water content helps you meet your quota. 

Myth or fact? Your ears are still growing.
FACT. Your outer ears are. Starting at birth, the ears are, proportionally, the body's largest feature, with a Spock-like prominence. They grow rapidly until about age 10, then slow to the languid pace of about 0.22 millimeter per year, according to a study by Britain's Royal College of General Practitioners. Other studies show that the earlobe itself also lengthens throughout life (men have longer lobes than women). However, the size of the ear canal, which is formed by bone and cartilage, does not increase into old age.

Myth or fact? Eating tomatoes can help prevent sunburn.
FACT. This is true, thanks to tomatoes' high lycopene content. Volunteers in one study who consumed 5 tablespoons of tomato paste daily for three months had 25 percent more protection against sunburn. Even better, skin had more collagen, which prevents sagging. German scientists also report that higher skin levels of this antioxidant correlate to fewer fine lines and furrows. Toss some on top of some romaine lettuce for the perfect skin-health salad: six leaves of romaine lettuce provide more than 100 percent of your daily value of vitamin A, which revitalizes skin by increasing cell turnover.

Myth or fact? When it comes to beauty products, expensive brands work better than mass-market products.
MYTH. Mass lines make more money, so they can afford more research and development. Among the best: Unilever (which does Dove and Ponds), L'Oréal (Vichy and La Roche-Posay), and Johnson & Johnson (maker of Neutrogena and Aveeno, which has its own research institute). A recent study found that 80 percent of women who followed a skin care regimen with mass-market products showed fewer wrinkles and healthier skin than when they used pricier lines.

 

Poorer heavy kids may suffer more heart woes

Study suggests children in affluent areas may be fat, but not unhealthy

Overweight children from lower- and middle-income neighborhoods may fall short of their thinner peers in one measure of cardiovascular fitness — but the same may not be true of those from more affluent areas, a new study suggests.

Researchers found that among 480 children and teenagers who underwent treadmill exercise tests, those with a high body mass index tended to have a slower heart rate recovery after their workout — but only if they were from lower- or middle-income neighborhoods.

Extra pounds did not generally seem to affect heart rate recovery among kids from the highest-income areas, the study found.

Heart rate recovery refers to the amount of time it takes a person's heart rate to return to its resting rate after a bout of exercise. It is one measure of cardiovascular fitness.

It's not certain why a high BMI would affect kids' heart rate recovery differently based on income, but there are a couple potential explanations, according to lead researcher Dr. Tajinder P. Singh, of Children's Hospital Boston.

One has to do with how BMI is calculated, he told Reuters Health in an e-mail.

BMI is a measure of weight in relation to height, but it does not differentiate between weight from body fat and weight from muscle. It's possible, Singh said, that children and teens from more advantaged families were more likely than their peers to have a high BMI because of muscle mass.

Another potential explanation, Singh speculated, is that kids from affluent neighborhoods have healthier lifestyles — better diets, more opportunities for exercise — so that even if they are overweight, they may be in good health.

Whatever the reasons for the findings, Singh said they suggest that lower- to middle-income children stand to gain the most from losing excess weight.

The findings, published in the Archives of Pediatrics & Adolescent Medicine, are based on the records of 480 children who underwent exercise testing at Children's Hospital Boston because of symptoms such as breathlessness and heart palpitations during physical activity. The tests were done to rule out heart disease, and all of the children had normal results.

Singh's team divided the children into three groups based on the socioeconomics of their neighborhoods. In the most affluent neighborhoods, the median household income was just over $100,000, and two-thirds of residents older than 25 had a college degree. In the least advantaged neighborhoods, the median income was $40,000, and 19 percent of residents older than 25 had a college degree.

Of all 480 children and teens, 70 percent had a normal BMI while the rest had a high BMI — with 17 percent falling into the "overweight" BMI category and 13 percent into the obese category.

Heart rate recovery was measured one minute after the children completed their exercise tests. Overall, Singh's team found that in the lower- and middle-income groups, overweight kids were slower to return to their pre-exercise heart rate than their normal-BMI counterparts.

On the other hand, normal-weight kids had similar heart rate recovery results regardless of socioeconomics.

One implication of the findings, Singh said, is that "children who have normal weight are likely to have good cardiovascular health irrespective of their socioeconomic position."

Another, he added, is that while weight loss is important for all kids who are overweight or obese, it may be "most immediately beneficial" for those from lower- to middle-income families.

Studies in adults have linked slower heart rate recovery to a higher risk of heart disease. But there are no studies on whether slower recovery in children predicts an increased risk of heart problems later in life.

 

Lasers scan future possibilities

Lasers have already had a profound impact on our daily lives but the potential of the technology has only just been tapped, scientists believe.

Sunday marks the 50th anniversary of the first demonstration of a ruby laser at the Hughes Research Labs in the US.

The light beams have since found myriad uses, from scanning shop prices to trying to sense the ripples in space-time made by colliding black holes.

Researchers say the coming decades will see even more remarkable progress.

"The laser gave a capability over previous light sources that was just so immense that you simply can't digest and exhaust all that in the matter of a few decades," said David Hanna, emeritus professor at the Optoelectronics Research Centre, University of Southampton, UK.

People have to use their imagination about what amazing and crazy things can be done with all that capability," he told BBC News.

There is debate over which key technological step made the laser possible, but Theodore Maiman's success in stimulating a ruby rod to produce an intense narrow beam of light by shining a flash lamp on it was an undoubted landmark.

There had been a race to demonstrate "light amplification by stimulated emission of radiation" (Laser), and Maiman beat everyone to it on 16 May, 1960.

At the time, the technology was said to be the classic "solution looking for a problem", but its ability to direct a powerful stream of energy from one location to another soon opened up a world of possibilities.

Anyone who scans a tin of beans at the checkout is using a laser. Anyone who listens to music on a CD is using a laser to read data stored on a disc. Anyone who sends an e-mail is reliant on the lasers that drive the world's fibre optic communications networks. Anyone who gets into a car is sitting in a box that owes its construction to lasers.

"There is a phenomenal amount of laser processing on a car; you wouldn't believe how much - laser cutting, marking, measurement, drilling, hardening, laser brazing, laser deposition, and laser welding," explained Tim Holt, the chief executive of the Institute of Photonics, University of Strathclyde.

"Modern cars today would not be possible without lasers."

THEODORE MAIMAN'S LASER (1) A powerful lamp is wrapped around a ruby rod, depositing energy in the form of undirected light of many colours, or wavelengths (2) Atoms in the rod absorb and store energy from the light (3) Reflecting mirrors then allow a small amount of light to bounce back and forth in the rod, collecting some of the atoms' stored energy on each pass (4) Some of the light escapes through one of the mirrors; it is a directed, intense beam of synchronised light waves of a specific colour

The worldwide market in lasers is worth some $5-7bn annually. Most of that value is in lasers sold to manufacturing outlets for use in material processing, but the two other key markets are lasers for use in communications systems and in data storage.

But as much as lasers have infiltrated our everyday world, there is still much more they could do, scientists believe.

There is hope lasers could provide us with a near-limitless supply of clean power.

Laser cutters deliver a lot of energy to a very specific spot

In the US, the National Ignition Facility will soon train 192 giant laser beams on a tiny pellet of hydrogen fuel in an attempt to fuse the element to make helium, and so release a colossal amount of energy - much like the Sun does at its core.

In Europe, researchers want to take this approach forward in a project known as HiPER that would be the prototype power station of the future.

"It's possible to use lasers to crush and heat material to temperatures that are 10 times hotter than at the centre of the Sun," says Dr Kate Lancaster from the UK's Central Laser Facility in Didcot.

"A standard laser pointer is about a milliwatt; we'll be approaching a petawatt - 10 million million times more powerful than a standard lightbulb.

"Fusion would be immensely efficient but it's extremely hard to do. Ever since Maiman demonstrated his laser, however, people have realised that this technique should be possible."

In astronomy, lasers are already used to sharpen the images of the world's very best telescopes. By projecting a "reference star" on the sky, scientists can work out how to correct their observations for the distortions introduced by atmospheric turbulence.

Fibre lasers allow far more data to be transferred much faster

But lasers are also pioneering a completely new form of astronomy, one that attempts to probe the Universe without the need to detect light. These laser interferometers would measure the disturbances in the very fabric of space-time generated every time massive stars imploded.

Such gravitational waves are extremely weak, however, and only lasers have the precision to measure their passing. If the technique works, it should be possible to see remnant gravitational radiation from the very moment of creation itself.

And in medicine, too, the possibilities seem boundless. Lasers can be used to manipulate atoms and molecules, "to unfold proteins and tickle DNA", says Dr Lancaster.

"Lasers can accelerate particles to high energy and we can use that to treat cancer," she adds.

"At the moment, with the way we treat cancer with radiation, photons travel into the body and they deposit energy in healthy tissue as well as at the cancer site.

"Whereas when protons and ions travel into the body, they will deposit most of their energy only at the very end of their range. So we can use lasers to tune protons to deposit their energy just within the tumour site."

The world's biggest telescopes use lasers to sharpen their images

As lasers have got ever more powerful, their pulse rate has also pushed new boundaries.

We already have lasers that trace time at the femtosecond level - a thousandth of a millionth of a millionth of a second. Researchers now are also working on attosecond lasers, which count time in divisions of a millionth of a millionth of a millionth of a second.

Working at these scales, it is possible to see how matter works, to record for example the moment chemical reactions occur.

"On the femtosecond timescale, the atoms in a molecule will vibrate. So that is the relevant timescale for taking a detailed look at what is going on - as it happens - in a molecule," Professor Hanna told BBC News.

Divide that tiny time by 10 - a reduction of an "order of magnitude", as it is known - three times over, and science can now speak of what happens in attoseconds. This, Professor Hanna explained, is the timescale of processes inside the very atoms that make up molecules.

"Every time we pick up an extra order of magnitude - and there are many more to be got - we need to go back to the drawing board and think 'what on Earth do we do with that?'."

Bees make nests out of colorful petals

Flowery walls line a waterproof home for larvae

Not all bees toil in wax beehives — some live in the lap of luxury, building nests lined with colorful flower petals, a new study finds.

The Middle Eastern bee in question, Osmia avoseta, is a solitary species, as nearly 75 percent of the some 20,000 bee species are, meaning that each individual bee lives by itself.

In nests that are 0.5 to 2 inches (1.5 to 5 centimeters) beneath the ground, the females of this species line the one or two chambers of each nest with overlapping pink, yellow, blue and purple petals, starting from the bottom. 

The female then plasters a layer of claylike mud onto the petals just a half-millimeter wide — less than half the thickness of a dime — and finishes the lining with another layer of petals, essentially creating a petal sandwich.

The bees then deposit a sticky, nutritious mix of nectar and pollen on the chamber floor, lay an egg, and seal the chamber up by carefully folding the petals at the top and plugging it with mud.

This nursery then hardens, like the shell of a nut, to protect the insides against predators. As such, the offspring remain safe after they hatch, devour their rations, spin cocoons and fall into a 10-month sleep within their plush digs until they emerge mature in the spring.

"Unfortunately, her larvae never enjoy the brilliant colors of the nest's walls because they have no eyes," said researcher Jerome Rozen, curator in the division of invertebrate zoology at the American Museum of Natural History in New York. "And, anyhow, they would need a flashlight."

A closed brood cell of the bee species known as Osmia avoseta is lined with colorful flower petals.

These petal sandwiches likely help keep water both in and out of the nests. By keeping humid air in, the food the mother leaves behind remains moist and soft enough to eat.

By shutting water out, the nests don't get flooded during storms and could even float like bubbles if they got washed out from the ground.

"The architecture of the way these whole things are constructed is quite remarkable," Rozen told LiveScience.

In a rare coincidence, as Rozen and colleagues made their discovery while working near Turkey's Antalya province, another group of researchers made the same find the same day in a field in Iran's Fars province.

"It was absolute synchronicity that we all discovered this uncommon behavior on the same day," Rozen said.

 

Bat studies to aid roving robots

Detailed studies of the ways bats and dolphins use sound to echo-locate could soon help people with cochlear implants listen in stereo.

The research could also help robots improve how they find their way around hazardous environments.

The studies have revealed some of the tricks echo-locating animals use when catching prey.

Adapting the tricks should produce artificial systems that do a better job of locating static and moving objects.

Sound lesson

Bats and dolphins are well-known for their use of sound but relatively little is known about all the mechanisms that underlie this ability, said Professor Robert Allen from the University of Southampton who has co-ordinated the investigation into echo-location.

The research project, called Biologically Inspired Acoustic Systems (BIAS), has looked at the physiology of echo-locators, particularly bats, and how they structure the sounds they emit to help them navigate and catch prey.

"Colleagues at Leeds University have produced casts of bat heads and we're able to bounce sound off them to see what happens and to try to understand how the head shape affects the echoes received at the ears," said Professor Allen. "These are fundamental studies."

In parallel with these laboratory studies, a small, lightweight backpack has been developed that can be strapped to adult Egyptian fruit bats to listen to the sounds they emit while flying.

It was important to be close to the origin of a signal, said Professor Allen, because some of the subtleties of emitted sounds and their echoes will be lost with a microphone that records bats as they fly past.

The recordings have revealed the complexity of the sounds that some bats emit. The creatures being studied by researchers from the University of Leeds and Stratchclyde emit pulses of sound at fixed and fluctuating frequencies and many typically last only a quarter of a millisecond.

The fixed frequency pulses seem to help work out, via doppler shift, how prey, for example, is moving relative to the bat.

The joint Leeds and Strathclyde work is looking at developing ultrasonic transducers that can be used in small robotic vehicles that can go to places that are too dangerous or small for humans to get at.

"We're currently looking to apply these methods to positioning of robotic vehicles, which are used for structural testing," said Simon Whiteley from the centre for ultrasonic engineering at Strathclyde.

The robots might be able to use the echo-locating techniques to spot cracks in the walls of reactors or containment vessels.

Dr Whiteley and colleagues published their results in the journal Bioinspiration & Biomimetics.

Other pulses are used to help the bat focus on an object, spot very small objects and time their attack.

Chirps, sounds that start at one frequency and slide up or down to another over a short interval, help the bat spot where an insect is. The frequencies a bat uses are related to the size of its prey and the size of the bat.

The researchers also found that overlapping signals let bats spot objects that are smaller than the wavelengths of the sounds they emit. Researchers are pursuing this insight to see how it can help improve the resolution of sound-based imaging systems.

Hearing textures The researchers also looked at the way that dolphins echolocate

"Some bats have a very sensitive region of the cochlear around their call frequency so they can use doppler shift to get information as to whether an insect is flying towards or away from them," said Professor Allen.

For instance, he said, the sophisticated sound signals give a bat clues about the texture of an object. Adapting this could make medical ultrasound systems more sensitive and able to pick out different tissue types beneath the skin.

Research partners are also looking at using this technique to help in probing the ground for oil or other mineral deposits. Work is now going on to bounce the signals off different types of geological materials to determine the signals they reflect.

One application being pursued is adapting the way that bats process sound to improve the location-finding abilities of hearing-impaired people with a hearing aid or a cochlear implant.