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Wednesday, 1 August 2012
Thursday, 29 March 2012
Scientists often study fruit fly behavior to try to understand how the human brain works. The new fruit fly sleep study may suggest answers to one of the biggest questions among sleep researchers. “That is, ‘What is the core function of sleep?’ ” neuroscientist David Raizen told Science News. Raizen, who did not work on the new experiment, studies the brain and the nervous system at the University of Pennsylvania in Philadelphia.
Genes, chemical features present on chromosomes inside cells, determine many properties of an organism. “Rovers” are fruit flies that can tolerate sleep deprivation, thanks to a change in one of their genes. Among fruit flies, a gene called foraging determines how well the animal can function with little sleep. Scientists refer to another group of fruit flies as “sitters” — insects that need more sleep. The difference in performance of rovers and sitters arises from their hosting different versions of the foraging gene. (Scientists often give fruit fly genes unusual or humorous names; other examples include tinman, maggie, hamlet, hairy and bazooka.)
In the new study, scientists found that rovers could learn new things and keep their memories sharp even after a night without snoozing. The scientists were impressed by the bugs’ abilities. Paul Shaw, a neuroscientist from Washington University in St. Louis who worked on the study, described the insects to Science News as “über-duper super flies.” Sitter flies, on the other hand, had trouble learning if they went a night without sleep.
The tables turned, however, once food entered the picture. When sleep-deprived sitter flies weren’t allowed to eat for 12 hours, their memories improved. Not sleeping made their brains fuzzy — but not eating sharpened their memories. When food was withheld from rovers, the opposite happened: The flies got loopy and were unable to remember. While sitter flies could survive for a few days without food, the rover flies died after 41 hours when deprived of food.
The scientists found that even though rovers could survive sleep deprivation, they had a hard time with food shortages. That balance may explain why both rovers and sitters exist in nature. When food is abundant, rovers may dominate. But in times of shortage, their numbers probably drop off.
Shaw told Science News that there’s a message for people in the fruit fly study. “All of us ‘weak’ people who need eight hours a night might take comfort in the fact that those who claim not to need as much won’t be as resilient to everything,” he said.
Wednesday, 7 March 2012
Inside your body, sugar goes hand-in-hand with a substance called insulin. A type of hormone, insulin regulates the activity of cells and tissues. It calls the shots after you devour that delicious donut, helping organs pluck a type of sugar called glucose from the bloodstream. When insulin is missing or doesn’t do its job, sugar accumulates in the blood instead of getting into and feeding cells. This throws the body’s balance out of whack, causing a disease called diabetes.
An organ called the pancreas, near the beginning of the large intestine, produces insulin. The more glucose that tickles the pancreas, the more insulin it produces to process the sugar. But new studies show that other things can also cause the pancreas to release insulin. In one study, a sugar called fructose boosted insulin levels; in another, a common pollutant called bisphenol A (BPA) caused the same reaction.
Fructose gives fruit, honey and high-fructose corn syrup their sweetness. Nutritionists — backed by scientific studies — say we eat too much high-fructose corn syrup, found in foods from soft drinks to salad dressing. Scientists working on one of the new studies used human cells, mouse cells and live mice to study what happens when fructose meets the pancreas.
The team found that cells in the pancreas can “taste” the fructose, in a process similar to how the tongue tastes sugar. The study, like many other recent discoveries, shows that taste buds can occur — and taste chemicals — far from the tongue. Fructose alone didn’t boost insulin levels. But in the study, when glucose and fructose appeared together, the pancreas produced more insulin than it did when it encountered glucose alone.
“The system seems to be elegantly made to keep a balance,” Björn Tyrberg told Science News. Tyrberg, who led the new work, studies the biology of cells at Sanford-Burnham Medical Research Institute in Orlando, Fla.
The body may have a hard time keeping that balance in the presence of BPA, too. This chemical, commonly found in plastics and cash register receipts, can imitate a hormone called estrogen. One of estrogen’s jobs is to keep track of insulin, telling the pancreas to produce more if it is needed.
In the second new study, scientists found that BPA, like estrogen, can trigger insulin production. But because BPA is a pollutant, it stimulates the pancreas to create insulin when it’s not needed. The researchers also demonstrated that it doesn’t take much BPA to get the pancreas to pump out extra insulin. BPA and fructose may be radically different compounds, but both can throw off the body’s balance in similar ways.
Angel Nadal of Miguel Hernández University in Elche, Spain, led the BPA study. He told Science News that extra insulin in the blood may cause other tissues to start ignoring this important hormone. Called “insulin resistance,” this condition can lead to the buildup of glucose in the blood indicative of type 2 diabetes. In experiments by Nadal and his colleagues, animals exposed to BPA ended up with insulin resistance more often than other animals did. Nadal thinks that BPA in the body may speed up the onset of type 2 diabetes in people with a family history of the disease.
Franck Mauvais-Jarvis of Northwestern University’s Feinberg School of Medicine in Chicago told Science News that he doesn’t think BPA alone can cause diabetes. Lots of different chemicals can throw off the body’s balance. He says, “I suspect it’s a cocktail of these nasties” that can make a person more likely to develop the disease.
pancreas A large gland located behind the stomach. It secretes digestive enzymes (proteins that stimulate or speed up chemical reactions) into the intestines. It also secretes the hormone insulin into the blood.
insulin A hormone produced in the pancreas. It regulates the amount of glucose in the blood. A lack of insulin or a loss in the body’s responsiveness to it can both cause diabetes.
fructose A simple sugar found in honey and fruit and the sugar that makes up half of each molecule of sucrose, or table sugar.
glucose A simple sugar that is an important energy source in living organisms and a component of many carbohydrates. It also makes up half of each molecule of sucrose, or table sugar.
hormone A regulatory substance produced in an organism and transported in tissue fluids such as blood to stimulate the activity of specific cells or tissues.
Sunday, 22 January 2012
This story is being written by a person sitting in a bathtub. It doesn’t have water in it, because the person is fully dressed and typing on a laptop computer. This isn’t the most convenient place to work, with a file folder of notes propped on a soap dish and awkward conversations when someone else in the house thumps on the door and asks what’s taking so long.
Bathtubs, however, are very comforting for people writing about tiny, crawling bugs that suck blood. After reading about bugs with needlelike mouthparts that stick into a person’s arm unnoticed (at first, before the itching starts), it’s easy to wonder if that little tickle was a bug tiptoeing on your neck. Or just over and under your sock. A bathtub doesn’t have a lot of places for bugs to hide. A person starting to scratch and twitch can just stand up and look at all the smooth white surfaces to check for anything dark and crawling. That’s why I’ve chosen a bathtub as a place to write about bedbugs, also known as Cimex lectularius.
These insects had become rare in many parts of the world starting in the middle of the last century. That’s when powerful pesticides — or chemicals for killing pests — first came into widespread use. But bedbugs in just a few years developed ways to resist being killed by one of the more widely used early pesticides, DDT. Over more generations, the bugs developed ways to resist other pesticides. And so in the 1990s, bedbugs began to reemerge as a major scourge, and not just in the United States. They also began busting out as a big problem in Europe, Australia and parts of Asia.
Bedbugs don’t kill people or — as far as we know — directly transmit diseases. In 2011, a scientific paper raised questions about whether bedbugs might transmit infections. Tests in Vancouver, Canada, found the bugs carry two kinds of harmful bacteria, nicknamed MRSA and VRE. These germs can cause deep, oozing sores and other infections that very few drugs will treat.A grown-up bedbug (shown close up, thankfully) draws blood through its tubelike mouth. Still only about the size of an apple seed, adults are easy to overlook when they hide in mattress seams or slip into electrical outlets. Credit: Piotr Naskrecki
But a lot of people already have those bacteria on their skin. So it’s not clear whether bedbugs increase human infections with MRSA and VRE, points out Jody Gangloff-Kaufmann of Cornell University. She works on Long Island in New York.
Tiny bugs, big problems
Gangloff-Kaufmann specializes in insects common in towns and cities. Because bedbugs were rare when she was a kid, she had no experience with them. So to prepare for working with the returning menace, she found bedbugs and intentionally let them bite her.
Even if bedbugs don’t increase infections, their bites are not fun, she notes. The insects spend the day clustered in small, dark crevices, such as the seams in a mattress or grooves in a bed’s wooden headboard. In the dark, they hike out, covering perhaps the length of a room, to stick those needlelike mouthparts into flesh for a good, warm drink. The bite doesn’t sting like a bee’s. Quite the opposite. A sleeping person usually keeps on sleeping while the bug slurps.
The trouble comes from the bedbug’s spit. While feeding, some of the bug’s spit enters the little hole pierced into a person’s skin. Many people are allergic to several substances in the spit. So bites can swell into red bumps, often in clusters that can look like a spotty rash, and itch insanely.
The problems don’t end there. Bites themselves may become infected, especially if the sufferer scratches the bump open. People can lose sleep and grow miserable and anxious in their own homes. Also, friends and family may avoid visiting the homes of bedbug sufferers for fear of picking up the bugs. And like many allergies, somebody’s response to bedbug bites tends to grow stronger with repeated bites. Gangloff-Kaufmann, for example, says that her first bite took days to swell into a slight bump. People who have been bitten often may start itching within hours.The long sharp tube (colored purple in the magnified photo) on a bedbug’s mouth can stab sleeping people without waking them up. By the time people start to feel the itching caused by a bite, the bedbug has usually crawled away. Credit: Janice Haney Carr
“Bedbugs are not everywhere, but they can be anywhere,” Gangloff-Kaufmann says. The bugs can squeeze through very tiny cracks, which explains why pest control workers have discovered them in such places as a stereo, TV remote, clock radio — even in the chink in the bricks of a fireplace. In the past few years, reports have emerged of bedbugs having moved into hotels, movie theaters, ambulances, hospitals, college dormitories, airport lounges, clothing stores, government office buildings and lots of other places.
A blood-only diet
Bedbugs feed on more than just humans. On chicken farms, bedbugs attack chickens. Special species of the insects lurk where bats sleep. Other bedbugs thrive in the bird cities that cliff swallows build. Bedbugs don’t need beds. They just need blood.A close-up of the frame of a lounge chair shows bedbugs of various ages and their dark poop spots and cast-off exoskeletons. The straight bars are staples. Credit: louento.pix/flickr
Not all blood-eating insects need all blood, all the time. Among mosquitoes, for example, blood is for females only. Males don’t touch the stuff, relying on other classic insect foods, such as nectar sipped from flowers. Bedbugs, however, really do live the vampire lifestyle. For them it’s blood and nothing else.
A bedbug hatchling right out of the egg needs at least one hearty, warm, red meal to make it to the next stage of growth. As bedbugs reach adulthood and become about the size and color of an apple seed, they still need blood. A blood meal allows a bedbug to graduate to its next phase of life. For example, before mating, both males and females feed on blood to build up their strength.
But these insects can survive a long time between meals. Just how long depends on the conditions. A study from the 1940s found that bedbugs lived up to 18 months with no blood in a cool (45 degrees Fahrenheit), humid place, but only about six months at 73º F. Experiments with modern bedbugs suggest they may not be as tough.
The need for blood presents a puzzle for scientists who keep bedbugs in the lab to study. Stephen Kells, from the University of Minnesota in St. Paul, says that it took about a year for his lab to figure out how to get the insects to eat reliably. During one tough period when progress seemed to have stalled, one of Kells’ collaborators kept hope and the bugs alive by letting them bite him. Fortunately, the researchers worked out a less-painful system: feeding the insects human blood from blood banks.
Harold Harlan, a retired military expert on the pests, kept his bugs alive by letting them bite him regularly for decades. He explains that he couldn’t find other volunteers, and his wife would have been too upset if he’d used their dog.
Battling the bloodsuckers
Researchers are starting to look at the tough problem of how to control bedbugs — both inside labs and homes. Pyrethroids, the main group of pesticides considered okay to use against bedbugs in people’s houses, no longer reliably kill these pests. Researchers at Ohio State University and elsewhere are now studying bedbugs’ DNA, a long molecule that carries genetic information and is found in nearly every cell of every living organism. The scientists are looking for genetic changes that have allowed the bugs to become immune to these poisons.
With pesticides looking like an iffy solution, other researchers are trying to understand the world as bedbugs smell and taste it. This work, the scientists hope, might someday pinpoint chemicals that could improve bug traps or suggest other tricks for fighting back.A pair of bedbugs in the act of mating has been flipped upside down to show the male’s position. He does not bother finding the opening to the tube in the female’s body that leads to her reproductive parts. Instead he just punches through her outer body covering. In bedbugs this method actually works. Credit: Rickard Ignell/Swedish University of Agricultural Sciences
Bedbugs find people in part by sniffing them — and the carbon dioxide that people breathe out appears to strongly attract the bugs. The insects also respond to human skin scents detected from more than twice a human arm’s length away. Whiffs of skin oils or earwax seem to be bug versions of “Mmm, what’s for dinner?” scents. The smell of human perspiration doesn’t appeal, though. Nor, oddly enough, does the smell of plain human blood, either fresh or dried.
Bedbugs make their own chemicals, including some that draw the bugs together in their daytime hideaways. Researchers have also found a compound that males release if another male grabs them and tries to mate. It’s sort of a “Whoa, there, I’m a guy too” signal. It comes in handy, as male bedbugs do seem to grab anything that’s the right size and moving.
Being grabbed by a male bedbug in a hopeful frame of mind looks like something not to take lightly. Males don’t look for a natural opening in the female’s body to insert sperm, their reproductive cells. Instead, males just use a sharp structure to punch a new hole through the female’s body wall. Luckily for bedbugs, the sperm do eventually manage to find their way to a female’s eggs.
For now, ridding one’s home of bedbugs is quite challenging. Treatments can involve heating all belongings, throwing away possessions that can’t be treated, steaming fabric surfaces and even heating whole rooms. So the best way to protect your own bed (or alarm clock or TV remote) is to learn what the bugs look like and check mattresses, sofas and fabric-covered chairs in homes, hotels and dormitories where you stay. Sometimes the easiest signs of these invaders are blood smears on sheets or the tiny black stains left by their poop.
And bedbug specialists cringe at the idea of even thinking about adopting furniture or electronics left out on curbs for free. Gangloff-Kaufmann has taught her young son to shout “bedbugs” whenever they drive by any such temptation. True, it’s creepy to think about bedbugs so much, but watching for them is the best defense.
And if that starts to creep you out, consider a nice sit in a dry tub to calm your nerves.
Pesticide: A poison for killing some kind of pest, such as bedbugs or disease-carrying mosquitoes.
Pesticide resistance: The power to live through being sprayed or treated with pesticides.
Pheromone: A chemical made by an animal. Pheromones drift through the air and send messages to other animals, saying such things as “danger” or “I’m looking for a mate.”
Carbon dioxide: A colorless, odorless gas produced by burning carbon and organic compounds and by breathing. It is naturally present in air and is absorbed by plants in photosynthesis.
Scourge: Something that causes pain or unhappiness.
DNA, or deoxyribonucleic acid: A long molecule in nearly all living organisms that carries genetic information. Each molecule of DNA consists of two strands coiled around each other to form a double helix, a structure like a twisted ladder.
On December 5, astronomers introduced a newly discovered planet that seemed habitable for extraterrestrial life. The faraway world is an exoplanet, or planet outside our solar system, called Kepler-22b. It looks E.T.-friendly because its temperature is neither too hot nor too cold for liquid water, which is essential to life as we know it. The planet orbits its star at just the right distance, sometimes called the “Goldilocks” zone.
Early studies suggested that the average temperature on the new planet hovers around 72 degrees Fahrenheit, room temperature for many places on Earth. Kepler-22b’s host star is a bit cooler than the sun, and the planet’s 290-day year is a bit shorter than Earth’s. This news left the scientific world abuzz.
“It’s a great gift,” space scientist Bill Borucki said at the conference introducing the planet. “We consider this sort of our Christmas planet.” Borucki works at NASA’s Ames Research Center, where he leads a team of scientists who look for planets using the Kepler Space Telescope.
Using this telescope’s data, scientists found that the planet’s radius is about 2.4 times Earth’s. (Radius is the distance from a sphere’s surface to its center.) That means Kepler-22b is larger than our planet but much smaller than giants like Jupiter and Saturn. Scientists don’t yet know if the planet is rocky, like Earth and Mars, or gassy, like Neptune and Uranus.
It didn’t take long after the discovery for other scientists to weigh in with doubts about the planet’s ability to support life. Planetary scientist Abel Mendez at the University of Puerto Rico in Arecibo studies and keeps track of possibly habitable planets. He told Science News that Kepler-22b doesn’t look promising.
Using data relayed from the space telescope, Mendez and his colleagues tested different possible combinations of size and mass for the planet. Mass is a measure of how much stuff is in an object. On Earth, objects with more mass weigh more. The scientists hoped to use mass as an indication of whether Kepler-22b might be even remotely Earthlike, and therefore able to support life.
Mendez thinks the new planet might support life if it were covered with water on its surface, like a giant ocean planet. But even then the chance of life is low, based on his team’s findings. “I’m not optimistic,” he said. “But I would love to be wrong.”
Sara Seager is a planet-hunting astronomer at the Massachusetts Institute of Technology in Cambridge. She told Science News that if the planet has an atmosphere, it should be hot and steamy and “too hot at the surface for life to survive.” Seager suspects the planet is gassy, like a miniature version of Neptune.
It’s still possible that the planet is rocky and surrounded by a thin atmosphere — or somewhat Earthlike. Scientists can’t know that, however, without further observations. But if Kepler-22b isn’t hospitable for E.T. or other life forms, that would be all right, too. Scientists have identified more than 2,000 possible planets using the new telescope’s data. Each planet has to be confirmed by follow-up studies, and 22b has already passed that second test. Perhaps another, more Earthlike planet is just waiting in the data.
Scientist Natalie Batalha from San Jose State University in California works on the Kepler telescope mission. She told Science News that of the thousands of potential planets just identified, hundreds might be small. “Not only do we have Earth-size planets, we have planets that are significantly smaller than Earth.
POWER WORDS (adapted from the New Oxford American Dictionary)
exoplanet A planet that orbits a star outside the solar system.
mass The quantity of matter that a body contains.
radius A straight line from the center to the circumference of a circle or sphere.
atmosphere The envelope of gases surrounding a planet.
James Bond and his enemies would be interested in the goings-on at the laboratory of John Rogers. So would Batman, the Spy Kids, Darth Vader and their enemies. That’s because Rogers, a materials scientist at the University of Illinois at Urbana-Champaign, mixes electronics with the human body to create new devices not found even in science fiction.
Make room, Lord Vader. There’s a new kind of cyborg in town.
Rogers and his collaborators have built an electronic device that’s smaller than a postage stamp and sticks to the skin like a temporary tattoo. The device’s possible users — patients, athletes, doctors, secret agents, you — are limited only by their imaginations.
Placed on a forehead, the device can record brainwaves; on the wrist, blood flow and muscle movement. On the skin of sick patients, it can track vital signs and watch for problems, replacing the bulky equipment usually found in hospitals. And stuck to the throat, it can function as a secret cell phone, activated by the movements of a person’s voice box.
The scientists designed the device, about half as thick as an ordinary sheet of paper, with skin in mind. Like skin, the electronic material can be stretched and squashed in many ways but keep on working.These skin-stuck devices mimic the properties of skin, which means they can stand up to poking, stretching and squeezing. Credit: Image courtesy John A. Rogers
Scientists who design devices for the body have to study how it functions, down to a tiny, cellular level. The body and the machine have to speak the same language. “We wanted to build devices that interact with the body,” Rogers says.
Last fall, Rogers and his colleagues demonstrated how their new device measures the body in different ways. The invention can record temperature, muscle motion or the electrical activity on a person’s skin. It may be outfitted with lights and a tiny power source, which means it can wirelessly transmit data to a nearby computer. This device may even change the way we think about medical tools and how doctors help their patients, inside and out.
Tattoos you can use
Rogers doesn’t have any permanent tattoos. But he says he’s been wearing “more and more” of the temporary kind to hide the stuck-on electronic circuits. (He even concealed one device behind a blue pirate tattoo.) Temporary tattoos use a simple and inexpensive way to adhere, or stick, to skin: a good sticky backing that stretches and flexes with skin’s natural motion.
Rogers and his colleagues have been experimenting with their new devices in the lab, taking various measurements of and from different parts of the body.Skin-based, or epidermal, electronic systems stick to the skin like temporary tattoos. Attached to the head, they can pick up electrical signals from the brain. Credit: Image courtesy John A. Rogers
“We’ve done extensive testing,” says Todd Coleman, an engineer who tackles the problem of getting the device, the body and the mind to “talk” to each other. “I put one [device] near my forearm and clenched my fist to see how it monitored my muscle signals and movements. If you put it on the surface of the head, it records brain waves. Near the heart, it picks up heartbeat information. It’s the same device, just in different places.”
The device is so light that a wearer may forget it’s there, says Coleman, now at the University of California San Diego. “We were trying to develop a piece of electronic material that is also basically completely invisible to the user. You barely even feel that the device is on your body,” he says.
More than skin deep
The scientists have found a way to extend the technology deeper than the body’s surface. In 2010, they introduced an electrical plastic wrap that can be attached to a person’s heart during open-heart surgery. Electronic circuits and instruments record blood flow and electric current, which means the material can alert doctors to hidden problems with a patient’s ticker. The team has already shown that a device attached to the surface of the brain can capture the electrical signals of an epileptic seizure.
Rogers, who says he’s always been drawn to science, regularly participated in science fairs as a kid. But as he got older, he realized that scientists’ work can create positive changes in the world.
“Making devices that have real benefits to society has been a real focus of our team, especially in recent years,” he says. “We are aiming to create devices that bring new ways to address health problems and other grand challenges in society.”An electroencephalograph, or EEG, detects and measures electrical signals from the brain. But the device, which requires a lot of wires and time, is ready for an upgrade. Credit: istockphoto
Spies and deep-sea divers might also take note of the new “skintronics”: Attached to the neck, for example, the devices could detect the throat movements of speaking. That means a person can mouth words — without making a peep — and the device would record the movements and relay the silent message. It would be perfect for covert operations.
“It’s unbelievable how much fun we’ve had having conversations with others about the device,” Coleman says.
Silicon: The problem and the answer
Scientists have been attaching electrical gadgets to skin for more than 80 years. In 1929, a German doctor named Hans Berger invented a device that attaches to the scalp and measures the brain’s electrical activity. His invention, called an electroencephalograph (EEG), lets doctors “read” brain activity. An EEG can help doctors diagnose diseases like epilepsy or detect when a patient slips into a coma.
But the EEG has a major drawback: It’s clunky. Technicians tape a complex web of small nodes and wires to the head to get a good read. And EEG’s need power, delivered through wires, which adds to the mess. That’s not just a problem for EEG’s; it’s a problem for almost every electrical device, even fictional bits of gadgetry used by Batman or James Bond.
A lighter, bendable device would provide the same information as an EEG, but without the heft. That idea started to seem like a reality in the early 1990s, when scientists around the world were racing to create flexible electronics. Computers became popular during this time, but most looked like clunky boxes attached to a nest of wires. Researchers envisioned flexible screens and computing devices that would bend and fold like paper.
Rogers wanted to go even further.
“I thought a more challenging goal might be to make an electronic device that bends like a sheet of paper but stretches like a rubber band,” he says.
A problem loomed. Computers depend on an element called silicon. In nature, silicon appears as a dark-gray crystal. Thin wafers of the material conduct electricity, and for decades silicon has been used to make computer chips and other electronic parts. Silicon is important, useful stuff. But silicon wafers are brittle, which means they break easily.
Rogers and his colleagues thought silicon perhaps could be made to bend like skin and not shatter. There wasn’t much they could do to the silicon material itself. But they thought arranging silicon wires into just the right shape might give the material more flexibility.An accordion player widens and narrows the instrument’s bellows (red in photo) to control the flow of air. Like bellows, electronic skin devices have a shape that allows material to compress and expand without breaking. Credit: Palmkvist Knudsen/Wikimedia
The scientists wanted silicon to expand like an accordion’s bellows, the part of the instrument that looks like a folded rubber sheet. When a person plays the accordion, the bellows unfold and move farther apart from each other without the material itself stretching. Rogers wanted to take a similar approach, designing the device so its wires could “unfold” — letting the silicon strands move — without shattering.
After three years of building and experimenting, Coleman says, the researchers produced a working device. Up close, the silicon looks like tiny, twisty snakes that wind through the material in complicated patterns. These winding silicon shapes form the different parts of the device — the sensors, antennae and power supply — and they can withstand stretching, poking and squeezing.
Mixing bodies and machines
In the not-so-distant future, surgery patients may find themselves wearing smart temporary tattoos, rather than bulky devices covered with wires. Rogers’ work is part of the growing field of “biointegrated technology,” devices built with the body in mind. They bring together machines and living things to improve lives. In the future, Rogers wants to extend the technology to create tiny devices that may even be able to operate independently within the body, improving, for example, the health of the human heart.
“The most immediate opportunity for biointegrated technology is to redefine what a surgical tool is,” he says. “My hope is that [the devices] will really have a large impact on the way that people think about surgical operations.” The ultimate goal, he says, is for the devices to track body and brain activity and “eliminate the need for surgical interventions in the first place.”
With his research group in San Diego, Coleman wants to create new ways for people to use their brains to talk to machines — or even each other. He imagines a world in which people can work together, or even think together, using the devices to transmit information directly from their minds. “You could interact with a friend in both the natural and virtual world, using not only your behavior but also your thoughts,” he says.Tiny snakelike strands of silicon are key to electronic skin devices’ success, allowing them to be flexible like skin. Credit: Image courtesy of John A. Rogers
The idea of connecting brains with the devices has implications in the classroom, too. “If we can monitor the brain signals between teachers and students who are interacting, then maybe we can learn the extent to which they understand each other,” Coleman says. “That could revolutionize education and training. It’s easy to imagine the possibilities. And if we don’t imagine, then what are we doing?”
POWER WORDS (adapted from the New Oxford American Dictionary and acs.org)
materials science The study of how a material’s structure is related to its properties.
electroencephalography The measurement of electrical activity in different parts of the brain and the recording of such activity as a visual trace.
epidermis The outer layer of skin.
silicon A nonmetal, semiconducting element used in making electronic circuits. Pure silicon exists in a shiny dark-gray crystalline form and as a shapeless powder.
You may not be familiar with the word tetrapod, but you know one when you see it. All tetrapods are vertebrates — animals with backbones — and most move on land. They also have four limbs — or their ancestors did, as in the case of snakes and whales, for example. Reptiles, birds and amphibians all count as tetrapods, as do mammals. You’re a tetrapod.
By studying fossils, scientists know that tetrapods haven’t always roamed Earth. They evolved from animals called lobe-finned fishes, which are named for their thick, strong fins. That means that over many generations, the fishes grew features that helped them move onto land. These features, which included longer limbs and digits, began appearing in the animals about 400 million years ago. (Digits are structures like fingers and toes at the end of a limb.)
While fossils provide evidence that tetrapods evolved from lobe-finned fishes, they don’t show how the animals learned to walk (or hop, or scuttle or fly). Now, a team of biologists has found evidence that animals were preparing to walk while still living underwater. In a new study, the researchers suggest that lobe-finned fishes pushed themselves around with fleshy fins long before they moved onto land and grew longer limbs and digits.
In the new work, the scientists didn’t scrutinize the fossil record. Instead, they pointed video cameras at living lobe-finned fishes called African lungfish and watched the animals scoot around the floor of an aquarium. Because lungfish are so closely related to tetrapods, scientists study the creatures to learn more about how ancient aquatic animals made a transition to living on land.
“The cool thing about the lungfish is that it’s walking underwater,” biologist Heather King told Science News. “And if lots of tetrapods were also doing this it could mean that the first step in the evolution of vertebrate walking took place underwater.”
King, from the University of Chicago, worked on the new study. Using cameras aimed at different angles, she and her colleagues recorded video footage of individual lungfish. The cameras showed that the animals push themselves along using alternating fins, just as animals use alternate legs to walk or crawl.
Neil Shubin, another University of Chicago biologist who worked on the study, said the recordings clearly show the animals’ motions. “If you asked me to tell you what those fins do just by looking at them, I’d give you a thousand functions, and walking wouldn’t be one of them,” he told Science News. “But that’s what they do.”
POWER WORDS (adapted from the New Oxford American Dictionary)
evolve To develop gradually over successive generations.
tetrapod A four-limbed animal, including amphibians, reptiles, birds and mammals.
digit A structure, like a finger or toe, at the end of the limbs of many vertebrates.
lobe A rounded and somewhat flat projection.
Saturday, 21 January 2012
To hungry humans, glow-in-the-dark food may seem suspicious and unappetizing. To creatures that swim, slither and crawl in the darkest depths of the ocean, however, a glowing bug may be a welcome and easy snack.
Scientists have come up with many ideas about why organisms light up. New experiments on tiny, glow-in-the-dark bacteria that live in the sea support the idea that a microbe’s glow isn’t just for show. Hungry animals are attracted to the light and eat the microbes, which then cruise around the ocean inside the animal’s guts. The idea is more than 30 years old, but new research from scientists in Israel and Germany boosts confidence in the theory.
“It’s terrific to see this experiment,” J. Woodland Hastings told Science News. Hastings, a biologist at Harvard University who specializes in studying critters that glow, was not involved in the study. “It’s nice to see these ideas confirmed.”
Lots of animals, from squid to fish, light up in the deep ocean. Inside their bodies, chemical reactions cause the glow, which is called bioluminescence.
To test the idea that the light helps bacteria attract the attention of animals and hitch a ride, Margarita Zarubin studied bacteria from 2,000 feet beneath the surface of the Red Sea. Zarubin, who is now finishing her doctorate at the Interuniversity Institute for Marine Sciences in Eilat, Israel, conducted the experiments while a student at the University of Germany in Oldenburg.
She began by placing brine shrimp in a tank with two kinds of deep-sea bacteria. One type glowed, the other didn’t. Hungry shrimp devoured the lighted bugs, but left the others alone. After eating the glowing bacteria, the shrimp also lit up — the bacteria glowed through the animals’ bodies.
“We could see the luminescence from inside their guts,” Zarubin told Science News.
Next, Zarubin and her colleagues took a step up the food chain. The team offered hungry fish glowing shrimp and nonglowing shrimp. Fish gobbled only the glowing shrimp; the other shrimp swam by in safety.
Finally, Zarubin and her team studied poop from the fish. The scientists found the bacteria alive and well, which meant they had survived the journey through shrimp and fish guts. Zarubin told Science News that this unusual mode of transport, hitching rides in intestines, spreads bacteria faster than natural movements of the ocean will.
Marine biologist Michael Latz of the Scripps Institution of Oceanography in La Jolla, Calif., told Science News that studying the gutsy journey of these bacteria may also help researchers understand how other germs spread through the sea.
POWER WORDS (adapted from the New Oxford American Dictionary)
bioluminescence The emission of light by living organisms such as fireflies and deep-sea fishes.
marine From or of the sea.
bacteria Members of a large group of single-celled microorganisms, including some that can cause disease.
food chain A series of organisms where each depends on the next as a source of food.
The viruses that cause “bird flu” spread easily among chickens, ducks and turkeys, often causing serious illness and sometimes death. These viruses don’t usually spread to humans, but it happens. And when it does, the results can be deadly. According to the Centers for Disease Control and Prevention, based in Atlanta, about 6 of every 10 people infected with the bird flu virus called H5N1 have died. If the virus ever did pass easily between people, it would cause widespread harm around the world.
Understandably, scientists want to know more about the virus and how it spreads to try to prevent a disaster. In two recent studies, scientists demonstrated how the virus could be changed to pass more easily between mammals, making it more infectious. (In the experiments, the scientists tested the virus on ferrets.)
In the hands of a bioterrorist who wants to cause harm on a large scale, such studies might be dangerous. They show how to turn H5N1 into a deadly biological weapon. That’s the concern of a committee organized by the National Institutes of Health (NIH), which is part of the U.S. government and the world’s largest medical research agency. The committee studied the new H5N1 papers and concluded that the virus could be made very dangerous, and that the new papers show how to do it.
An NIH statement from December 20, 2011, acknowledges that this kind of research can benefit the public. On the other hand, according to the statement, “Certain information obtained through such studies has the potential to be misused for harmful purposes.” The NIH argues that some of the information in the studies should be kept under lock and key — and only shared with certain scientists on a demonstrated need-to-know basis. If terrorists created an H5N1 virus that spreads easily, they could start a global health threat. The NIH panel has therefore recommended that the scientists and scientific journals publishing the studies release the conclusions of the experiments — but withhold the methods used to make the germ more infectious.
The U.S. government agrees with the panel’s recommendation. The government has formally requested, but not demanded, that scientists and journals hold back some of their new bird flu data. The editors of the journals are considering the request.
The U.S. government already has rules in place that permit only some people to know secrets about nuclear weapons. Scientists need access to information, but the same information should be kept away from people with the intent to harm. The question is: Who gets to decide which people can see the science, and how much of it?
The tricky part of this decision-making process is “drawing the line at which aspects of science are too risky to share,” Janet Raloff wrote in an article for Science News. Shrouding too much scientific research in secrecy may slow the advance of important scientific fields. But if studies like the recent H5N1 experiments always become public knowledge, they could offer terrorists easy access to dangerous new weapons.
This back-and-forth between the government and the scientific community over bird-flu data shows that both sides are struggling to find the right answer. It also shows that medical research has moved into sensitive terrain, where there are no easy answers.
POWER WORDS (adapted from the New Oxford American Dictionary)
flu, or influenza A highly contagious viral infection of the respiratory passages that causes fever, swelling and severe aching.
virus An infection-causing agent that typically has genetic material surrounded by a protein coat. A virus is too small to be seen under the microscope and is able to multiply only within the living cells of a host organism.
infectious Likely to be transmitted to people, organisms, etc., through the environment.
bioterrorism Terrorism involving the release of toxic biological agents.
Cleaning clothes usually requires soap and water to remove stains and smells, and a tumble in the dryer or an afternoon on the clothesline to dry. The time and energy needed to turn a heap of dirty laundry into a pile of clean clothes might make people wish for clothes that just clean themselves.
That wish is a step closer to coming true. Recent experiments show that cotton fabric coated with the right mixture of chemicals can dissolve stains and remove odors after only a few hours in the sun.
“The technology can be applied to all kinds of fabrics and their related products,” says materials scientist Mingce Long. He helped develop the treated cotton with his colleague Deyong Wu, both of China’s Shanghai Jiao Tong University.
The handy fabric gets its self-cleaning abilities from a chemical mixture that coats the cotton threads. The coating includes substances known as photocatalysts, which trigger chemical reactions in light. One of those photocatalysts, called titanium dioxide, helps sunscreen block the sun and is used as tattoo ink. Another, called silver iodide, is used for developing photographs.
Researchers have previously shown that titanium dioxide mixtures could remove stains in clothes — but with exposure to ultraviolet, not visible, light. (The waves of ultraviolet light are more energetic and shorter than those of visible light.) Other studies have demonstrated that silver iodide can speed up chemical reactions in sunlight.
“We knew that self-cleaning cotton fabrics with titanium dioxide coating had already been developed, but they cannot work, or they work weakly, under sunlight,” Long says. “If we want to use the fabrics in daily life, we must develop cotton that cleans itself under daylight.”
Long and Wu created just such a fabric, working for years to perfect the recipe for a liquid dip that left cotton coated with the titanium dioxide mixture. Then they added particles of silver iodide, which boosted the fabric’s self-cleaning ability in the sun. In laboratory tests, their creation was nearly seven times better at removing stains (and killing bacteria lurking in the clothing) than titanium dioxide alone.
The scientists can’t start selling their self-cleaning cotton just yet; scientists still need to make sure the coated cotton won’t harm those who wear it. Although titanium dioxide is used in some foods, recent experiments have shown that it can cause health problems if it gets in the lungs. So before the material can be worn, scientists need to find a way to make it safe.
Still, Long says that he hopes to wear self-cleaning clothes one day — and avoid having to do laundry. “Someday in the future, when I walk on the street,” he says, “I hope people are wearing self-cleaning clothes that originated from my technology.”
POWER WORDS (adapted from the New Oxford American Dictionary)
photocatalyst A substance that starts a chemical reaction when exposed to light.
chemical reaction A process that involves rearrangement of the molecules or structure of a substance, as opposed to a change in physical form.
titanium dioxide A white, unreactive, solid material that occurs naturally as a mineral and is used extensively as a white pigment.
silver iodide A yellow powder that darkens with exposure to light. It is used in photography and artificial rainmaking.
With March Madness right around the corner, basketball-watching season is in full swing. People who play or watch the sport know that the right shot can make or break a game. A swoosh through the hoops may bring the thrill of victory; a backboard bounce may give a team another chance.
Devoted fans aren’t the only ones watching pro basketball players and other athletes. Though top jocks may be well known for using their bodies, scientists have found that athletes’ brains also work hard while playing. Researchers are finding that during critical moments of the game, a player’s brain uses information differently than a fan’s, coach’s or other onlooker’s. These differences can help athletes make crucial decisions at breakneck speeds.
Salvatore Aglioti, a neuroscientist at Sapienza University of Rome, studies how the human brain processes images of the body. He’s interested in the differences and similarities between the real, physical world and the virtual one created and used by the brain to help a person understand his or her surroundings. Aglioti thinks that brain cells called mirror neurons might be particularly important among athletes.
Mirror neurons become active when a person does an action or when a person watches someone else do an action. These neurons behave the same whether you’re brushing your teeth or watching your friend brush her teeth. A basketball player’s mirror neurons fire when he’s playing and when he’s watching someone else play.
Mirror neurons may help a player predict what’s going to happen in a game. When a player’s brain uses mirror neurons to track the actions of an opponent, the player might be able to anticipate his opponent’s next move and quickly respond in the best way.
Aglioti designed a test to see if pro players were better than novices and spectators at anticipating another player’s moves. He showed each group time-lapse photographs of a player shooting, including the ball leaving the player’s hands. He compared the groups’ abilities to predict the success or failure of the shot.
“Compared to novices and scouts, elite athletes were better at predicting the outcome of a shot after watching the body motion of basketball players,” Aglioti told Science News.
A recent study of cricket athletes also showed that expert players take cues from body language to predict how the game will play out. And expert cricket players could better guess where a ball was headed if they were allowed to swing a bat while making their prediction — suggesting that imitating the action helps with anticipation.
Novice cricket players’ predictions did not get better with a bat in hand. The study suggests that an athlete’s ability may rely on a strong connection between the real world and the virtual one conjured in his or her brain.
Basketball fans waiting on the edges of their seats for the swoosh! or thwack! may not be thinking about mirror neurons and the science of imitation. But on the courts, imitating the moves of favorite players may put fans one step closer to their own three-pointers.
POWER WORDS (adapted from the New Oxford American Dictionary)
neuroscience Any of the sciences that deal with the structure or function of the nervous system and brain.
neuron A specialized cell transmitting nerve impulses; a nerve cell.
cricket An open-air game played on a large grass field with a ball, bats and two wickets, between teams of eleven players. The object of the game is to score more runs than the opposition.
Keeping track of water makes for tricky science. It drains through soil, slips through cracks in rocks and refills underwater reserves. It bubbles up through springs and runs in rivers. Water evaporates and forms clouds; rain brings it back to earth, where it keeps plants alive and drains into the soil again.
Scientists who study water’s movements recently reported that levels of groundwater — water found in soil or pooled in underground reservoirs — have been dropping for the last nine years in many places. Part of that decrease is probably due to human activities. People drill wells and pump water from deep underground pools, especially in dry areas, to grow crops and supply drinking water. The new study suggests we’re pumping out too much.
“People are using groundwater faster than it can be naturally recharged,” hydrologist Matthew Rodell told Science News. By recharged, he means faster than rains and snowmelt can replace withdrawn groundwater. When a resource is used faster than it’s replaced, its use is said to be unsustainable. Hydrologists like Rodell, from NASA’s Goddard Space Flight Center in Greenbelt, Md., study the ways water moves around Earth. Sooner or later, at the rates measured by Rodell and his colleagues, the resource could run dry.
The unsustainable groundwater-pumping pattern shows up all around the world, especially in places where agriculture has increased. Scientists detected declining water under the ground in India, southern Argentina, western Australia and some parts of the United States. Hydrologist Jay Famiglietti told Science News that underground water reserves in the world’s driest areas have been severely affected. Famiglietti, who also participated in the new study, works at the University of California Center for Hydrologic Modeling in Irvine.
The scientists’ measurements came from a surprising source: two satellites orbiting Earth. Nicknamed Tom and Jerry after the cartoon cat and mouse, they constantly chase each other around the planet. Instead of teasing and tormenting each other, though, the twin satellites track changes in groundwater by measuring gravity.
Gravity attracts anything with mass — the amount of stuff in something — to anything else with mass. It keeps Earth in orbit around the sun, and the moon in orbit around Earth. Thanks to gravity, people can walk on the ground instead of drifting off into space. Objects with more mass have a stronger gravitational pull on objects around them. The gravitational pull of a solid rock mountain on a satellite flying over it may be different from the ocean’s pull on the spacecraft.
Because of these changes in gravity, Tom and Jerry move farther apart or closer together as they fly over different parts of Earth. The two satellites constantly send signals to each other, keeping track of the distance between them. Like other masses, groundwater’s gravity tugs on the satellites. But as water flows, its mass moves around, changing its gravitational pull.
Tom and Jerry recorded these changes every month for nine years. The satellites, part of a mission called GRACE, began taking measurements in 2002. GRACE stands for Gravity Recovery and Climate Experiment, a collaboration between NASA and the German Aerospace Center.
Recent droughts may explain the drop in groundwater in some places, like Argentina and the southeastern United States. The main reason, however, is farming. To grow crops in places like northern India and the western United States, farmers pump enormous quantities of water from the ground. In the Middle East, farmers use groundwater that probably came from rain that fell thousands of years ago. In this dry area, groundwater isn’t likely to be replaced by more rain any time soon.
Scientists don’t know how serious the falling groundwater levels are. While Tom and Jerry show changes in the amount of water, they don’t show how much total water remains. Some of the reserves may meet water demand for hundreds of years; others might not. Some scientists, like hydrologist Leonard Konikow at the U.S. Geological Survey in Reston, Va., say people need to find ways to manage groundwater more responsibly.
“There are too many areas in the world where groundwater development far exceeds a sustainable level,” he told Science News. “Something will have to change.”
POWER WORDS (adapted from the New Oxford American Dictionary)
hydrology The science concerned with the properties of Earth’s water, especially its movement in relation to land.
gravity The natural force of attraction between any two massive bodies. The greater the mass and the smaller the distance between two objects, the greater the gravitational attraction.
satellite An artificial body placed in orbit around the moon, Earth or another planet in order to collect information or for communication.
mass The amount of matter, or stuff, that something contains.