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.

Working overtime increases heart risk, a study finds

Putting in long shifts may put extra strain on the heart, experts believe

People who regularly put in overtime and work 10 or 11-hour days increase their heart disease risk by nearly two-thirds, research suggests.

The findings come from a study of 6,000 British civil servants, published online in the European Heart Journal.

After accounting for known heart risk factors such as smoking, doctors found those who worked three to four hours of overtime a day ran a 60% higher risk.

Experts said the findings highlighted the importance of work-life balance.

Overall, there were 369 cases where people suffered heart disease that caused death, had a heart attack or developed angina.

And the number of hours spent working overtime appeared to be strongly linked in many cases.

The researchers said there could be a number of explanations for this.

People who spend more time at work have less time to exercise, relax and unwind.

They may also be more stressed, anxious, or have depression.

A career-minded person will also tend to be a "Type A" personality who is highly driven, aggressive or irritable, they say.

"Employees who work overtime may also be likely to work while ill - that is, be reluctant to be absent from work despite illness," they add.

Lead researcher Mianna Virtanen, an epidemiologist at the Finnish Institute of Occupational Health in Helsinki and University College London, said: "More research is needed before we can be confident that overtime work would cause coronary heart disease."

Cathy Ross, senior cardiac nurse at the British Heart Foundation, which part-funded the research, said: "This study raises further questions about how our working lives can influence our risk of heart disease.

"Although the researchers showed a link between working more than three hours overtime every day and heart problems, the reasons for the increased risk weren't clear.

"Until researchers understand how our working lives can affect the risk to our heart health, there are simple ways to look after your heart health at work, like taking a brisk walk at lunch, taking the stairs instead of the lift, or by swapping that biscuit for a piece of fruit."

Dr John Challenor, from the Society of Occupational Medicine, said: "In many ways it confirms what we as occupational health doctors already know - that work/life balance plays a vital role in well-being.

"Employers and patients need to be aware of all of the risk factors for coronary heart disease and should consider overtime as one factor that may lead to a number of medical conditions."

Laser could be used to make rain on demand

Being able to create enough droplets is a key challenge

Ultra-fast pulses from a powerful laser can create droplets of water out of thin air, according to a new study. With the right conditions and large enough droplets, the researchers say, the technique could be used to make rain on demand.

Rain forms when water condenses around tiny particles in the atmosphere. Most of the time, dust or pollen do the job, but humans have long attempted to speed the process by seeding clouds with chemicals like silver iodide. Those chemicals provide the so-called "condensation nuclei" that trigger the consolidation of water into raindrops.

Unfortunately, such methods are difficult and could have environmental side effects, said Jérôme Kasparian, an optical physicist at the University of Geneva, Switzerland who was on the team that demonstrated the laser-triggered condensation. The study was published online May 2 in the journal Nature Photonics. 

"The potential advantage of laser is that it can work continuously," Kasparian said. If lasers can trigger rain on a large scale, he said, it would also be more efficient and cheaper than spraying silver iodide out of airplanes or shooting it into the sky from rockets.

Researches have long known that short, strong laser pulses can ionize air molecules, creating pathways of ionized gas called plasma channels. Kasparian and his team wanted to find out whether those plasma channels could be of use to wannabe rainmakers.

"Our idea is to use the laser to ionize the air, and the ions that are produced can then serve as the condensation nuclei," Kasparian said.

To test the idea, the researchers first used an atmospheric cloud chamber, a box that enabled them to vary temperature and humidity. After saturating the air in the chamber, the team flipped on a several-terawatt laser (one terawatt is a trillion watts) and watched with surprise as visible water droplets formed. Three seconds after the laser pulsed, the droplets swelled to diameters of 80 micrometers, smaller than a raindrop but larger than expected.

"What was very amazing was the fact that the cloud was very well visible to the [naked] eye, so the effect was quite strong," Kasparian said.

The next step was to take the laser outside. Using a weaker laser to monitor the formation of foggy air, the team blasted their multiple-terawatt laser into the sky of Berlin in Autumn 2008. Again, they saw heartening evidence: Particles coalescing in the atmosphere.

"This means that the laser can trigger the formation of droplets inside a cloud chamber, [but also] in the real atmosphere," Kasparian said. "Now the challenge is to find conditions that will allow the droplets to grow further into the size where they will fall and get turned into rain."

 

New bone marrow transplant method eases risk

Experimental technique just tamps down, not destroys, immune system

Bone marrow transplants are undergoing a quiet revolution: No longer just for cancer, research is under way to ease the risks so they can target more people with diseases from sickle cell to deadly metabolic disorders.

The old way: High doses of radiation and chemotherapy wipe out a patient's own bone marrow before someone else's is infused to replace it, hopefully before infection strikes.

The new way: Rather than destroying the patient's bone marrow, just tamp it down enough to make space for the donated marrow to squeeze in alongside and a sort of twin immune system takes root. It's what doctors taking a page from mythology call "mixed-cell chimerism" — patient and donor blood and immune cells living together to improve health.

To find the best methods for these less intense transplants, different mixes of low-dose radiation and immune-suppressing drugs are under study at hospitals around the country.

But the ultimate quest is to allow transplants even when donors aren't a good genetic match, says Dr. Suzanne Ildstad of the University of Louisville — whose technique involves an experimental tweaking of donated cells to help them grow better.

"It makes it possible for anyone who has a mom or dad willing to donate marrow to them to have a transplant," says Ildstad, who has families with sickle cell and other childhood genetic illnesses lining up to try.

Separately, several hospitals are testing how to combine kidney transplants with bone marrow transplants from the same donor, in hopes that a hybrid immune system lessens the need for lifelong anti-rejection drugs.

"People are watching with eager expectation," says Dr. Lakshmanan Krishnamurti of Children's Hospital of Pittsburgh, who is helping to plan a multi-hospital study of some of the new methods for hard-to-treat adults with sickle cell disease.

Doctors have long known that a traditional bone marrow transplant can cure young children of sickle cell — if they have a well-matched donor. New marrow produces healthy red blood cells to replace the sickle-shaped ones that can't squeeze through small blood vessels, the cause of the disease's pain, infections and life-threatening organ damage.

But only about 17 percent of children have a suitable donor, usually a healthy sibling. Attempts to transplant adults have failed, their bodies too ravaged from years of the disease. Another hurdle: Certain immune cells in donated marrow sometimes become too aggressive and attack the recipient, called graft-versus-host disease or GVHD.

Enter the new research.

First came a tantalizing success in severely ill adults. Nine of 10 patients who underwent a less intense transplant — using low-dose radiation and two drugs to inhibit problem immune reactions — had their sickle cell apparently eliminated, Dr. John Tisdale and colleagues at the National Institutes of Health reported in December. They developed a hybrid immunity that produces normal red blood cells with no GVHD.

But those people had perfectly matched donor cells provided by healthy siblings. Few patients do.

Back in Louisville, Ildstad gives donated marrow a boost to try to overcome that problem while avoiding GVHD, a risk that worsens with mismatched donors. She removes troublesome immune cells from the donated infusion, leaving concentrated amounts of the blood-producing stem cells patients need plus "facilitating cells" that she discovered seem to help them take root.

In an NIH-funded experiment at Louisville and Duke University, the method so far worked in two children with sickle cell who had well-matched donors and one of four with a half-match.

Dr. Joseph Leventhal of Northwestern University gave an Ildstad-treated stem cell infusion to a handful of kidney transplant recipients who developed hybrid immune systems that seem to be holding nearly a year later. The first three treated are using one anti-rejection drug instead of the usual cocktail, and one soon will attempt full weaning.

"We're doing this in patients where it could have potentially the biggest impact," those with unrelated donors, says Leventhal, who anticipates giving one patient a month the dual transplant as the study continues at Northwestern Memorial Hospital.

The attraction to families: "You don't die from the new way," is how Bob Evanosky of Aurora, Ill., puts it.

His three sons have a devastating metabolic disease called metachromatic leukodystrophy, or MLD. Last summer, son John got an experimental outpatient transplant at Duke — a far cry from the months his brother Jack had to spend in intensive care after a well-matched transplant the old-fashioned way.

Dad was John's donor even though he's only a half-match — and the new cells are making the enzyme his body had lacked, too late to reverse the brain damage that has paralyzed the 8-year-old but perhaps able to ease some complications, says Evanosky, who plans to donate to his John's twin Christopher this fall.