Now, a new study of sleep in sparrows suggests that the link between sleep and the ability to learn may be more complicated than people realized. During migration season, these sparrows do well in learning tests even when they’ve had very little sleep.

White-crowned sparrows fly mostly by night and eat by day as they migrate up to 4,300 kilometers each spring and fall.

Niels C. Rattenborg, University of Wisconsin–Madison

White-crowned sparrows migrate enormous distances. In the spring, they fly 4,300 kilometers from southern California to Alaska. In the fall, they make the trip back. The sparrows fly at night and spend their days looking for food. This means that during migration, they get about one-third as much sleep as they do at other times of the year.

Niels C. Rattenborg of the University of Wisconsin–Madison wanted to find out how the sparrows were able to deal with getting so much less sleep. Also, could the birds get by with less sleep even when they weren’t migrating?

To find out, Rattenborg and his colleagues brought eight wild birds into a lab and monitored them for 1 year. They invented a game to check how well the birds could learn. In the game, the sparrows had to peck three buttons in a certain order to get a food treat.

The scientists discovered that the birds’ ability to learn the right button sequence depended on two things: the time of year and how much sleep the birds had had.

During migration season, the sparrows were restless at night and got much less sleep than usual. Even so, they were able to figure out how to get the food treats just as quickly as if they’d had a regular night of sleep.

Outside migration season, the scientists disturbed the birds at night to make sure they got less sleep than they normally would at that time of year. They found that the sparrows had much more difficulty learning how to get the food treats than birds that had a regular night’s sleep.

The results suggest that the sparrows can get by with much less sleep during the migration season than they can at other times of the year. If scientists can find out why this is, they may be able to learn from sparrows and find ways of helping people cope with lack of sleep.

Still, until scientists fully understand the relationship between sleep and learning, it’s better to play it safe and get plenty of shut-eye when getting ready for that next exam.—S. McDonagh

Going Deeper:

Milius, Susan. 2004. Sparrows cheat on sleep: Migratory birds are up at night but still stay sharp. Science News 166(July 17):38. Available at http://www.sciencenews.org/articles/20040717/fob7.asp .

You can learn more about the white-crowned sparrow at www.mbr-pwrc.usgs.gov/id/framlst/i5540id.html (U.S. Geological Survey) and birds.cornell.edu/BOW/WHCSPA/ (Cornell University).

Now, scientists have figured out how one particular parasite does it—by forcing its host sand fly to spit up.

Female sand flies are bloodsuckers that can carry Leishmania parasites from dogs, foxes, and other animals to humans.

Public Health Image Library

First, the parasite multiplies in a sand fly’s throat, floating in a blob of gel it makes for itself. Then, when the fly bites a person, the fly spits up, depositing the gel and its cargo of parasites into the person’s bloodstream. The infection spreads rapidly.

It sounds gross, but it’s definitely effective. About 12 million people around the world are infected with different species of these parasites, known as leishmania. Some species of these single-celled organisms are lethal. Leishmania mexicana, which the scientists studied, is one of the milder forms. If the infection isn’t treated, the parasite causes skin lesions that can leave severe scars.

Leishmania mexicana takes advantage of how sand flies make a living. These flies must feed on blood, from humans or other mammals, to survive. When a sand fly bites a mammal, the fly coughs up the blob of leishmania gel into the mammal’s bloodstream, sending countless parasites on their way.

Scientists at the University of Liverpool in England wanted to find out how important the gel is for the leishmania parasite to infect its host. If there were no gel, would the parasite still invade the new host successfully? They did some tests with mice to find out.

When they injected the parasite along with the gel, skin lesions appeared quickly. But when they injected the parasite on its own, without the gel, they found that skin lesions took longer to appear.

This result suggested that something in the gel gives the parasite a boost, speeding up the process of infection. The scientists then figured out that a particular type of protein in the gel is the important ingredient. But they’re not sure exactly how this protein does its job. If researchers can work out how the protein works, it may help them design a vaccine that can combat leishmania.

A new vaccine won’t help sand flies, though. Once infected, these little critters are stuck with leishmania—and the accompanying blobs of gel—for life.—S. McDonagh

Going Deeper:

Seppa, Nathan. 2004. Parasite pursuit: Sand fly coughs up leishmania protozoan’s secrets of proliferation. Science News 166(July 24):53. Available at http://www.sciencenews.org/articles/20040724/fob6.asp .

You can get information about Leishmania and the infections this parasite causes at www.cdc.gov/ncidod/dpd/parasites/leishmania/factsht_leishmania.htm and www.dpd.cdc.gov/dpdx/HTML/Leishmaniasis.htm (Centers for Disease Control and Prevention).

The Hyper-X recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound. That’s about 5,000 miles per hour. At this speed, you’d get around the world—flying along the equator—in less than 5 hours.

Powered by its scramjet engines (shown in gold), the black, unmanned X-43A flew at a record speed for an air-breathing jet plane. The experimental plane is only 12 feet long.

NASA

The Hyper-X is an unmanned, experimental aircraft just 12 feet long. It achieves hypersonic speed using a special sort of engine known as a scramjet. It may sound like something from a comic book, but engineers have been experimenting with scramjets since the 1960s.

For an engine to burn fuel and produce energy, it needs oxygen. A jet engine, like those on passenger airplanes, gets oxygen from the air. A rocket engine typically goes faster but has to carry its own supply of oxygen. A scramjet engine goes as fast as a rocket, but it doesn’t have to carry its own oxygen supply.

A scramjet’s special design allows it to extract oxygen from the air that flows through the engine. And it does so without letting the fast-moving air put out the combustion flames. However, a scramjet engine works properly only at speeds greater than five times the speed of sound.

A booster rocket carried the Hyper-X to an altitude of about 100,000 feet for its test flight. The aircraft’s record-beating flight lasted just 11 seconds.

In the future, engineers predict, airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Hypersonic airliners could carry passengers anywhere in the world in just a few hours.

Out of the three experimental Hyper-X aircraft built for NASA, only one is now left. The agency has plans for another, 11-second hypersonic flight, this time at 10 times the speed of sound.

Hang on tight!—S. McDonagh

Going Deeper:

Weiss, Peter. 2004. Soaring at hyperspeed: Long-sought technology finally propels a plane. Science News 165(April 3):213-214. Available at http://www.sciencenews.org/articles/20040403/fob6.asp .

You can learn more about NASA’s Hyper-X plane at oea.larc.nasa.gov/PAIS/FS-2003-07-77-LaRC.html and www.nasa.gov/missions/research/x43-main.html (NASA).

About 20 years ago, chemists discovered that carbon can form into molecules with the same shape. They nicknamed them buckyballs. These strong, hollow particles may someday be used to carry medicine or even block the action of certain viruses.

Scientists have now found that buckyballs can harm living cells. Research by Eva Oberdörster, a biologist at Southern Methodist University in Dallas, and her team shows that these molecules damage brain cells in fish.

A buckyball molecule (right) made up of 60 carbon atoms (blue spheres) has the same geometry as a soccer ball (left).

U.S. Department of Energy

Buckyballs belong to a group of materials known as nanomaterials. The prefix “nano” means one-billionth. A nanometer is one-billionth of a meter—roughly the width of just five carbon atoms lined up in a row. So, a buckyball is an extremely tiny particle—only a few ten-thousandths of the width of a human hair.

To make a nanomaterial, scientists manipulate individual atoms to build molecules of different shapes. Groups of these molecules form materials with particular characteristics, making them suitable for different jobs. For example, some nanomaterials are already being used in makeup and sunscreens.

Because buckyballs may someday be used in industry, Oberdörster and her team conducted experiments to find out if the molecules are toxic.

The researchers added different quantities of buckyballs to water in a fish tank. After 48 hours, they removed the fish from the tank and checked different parts of the fishes’ bodies for damage. Although none of them died, the exposed fish showed 17 times as much damage to brain cells as did fish not exposed to buckyballs.

In a separate experiment, Vicki Colvin of Rice University in Houston found that buckyballs damage human cells growing in a lab. But she also found a possible solution to the problem. Coating buckyballs with other kinds of simple molecules appears to make buckyballs safer.

Nanomaterial particles come in all sorts of sizes and shapes, so it’s not yet known whether they all have the same harmful effects that buckyballs do. It’s going to take a lot more experiments to sort out all the possible health effects of these amazing, new materials.—S. McDonagh

Going Deeper:

Goho, Alexandra. 2004. Tiny trouble: Nanoscale materials damage fish brains. Science News 165(April 3):211. Available at http://www.sciencenews.org/articles/20040403/fob1.asp .

Learn more about buckyballs by following the links at mathforum.org/alejandre/workshops/buckyball.html (Math Forum).

You can find images of some nanomaterials at www.zyvex.com/nanotech/visuals.html (Zyvex).

Instructions for building a buckyball are available at www.seed.slb.com/en/scictr/lab/buckyball/index.htm (Schlumberger).

Now, scientists have found a way to make diamonds even harder by cooking them under pressure with lots of heat. Using the new technique, Russell J. Hemley of the Carnegie Institution of Washington and his colleagues claim that they have made the hardest diamond crystal ever tested.

When exposed to high heat and pressure, diamonds become extremely hard.

Carnegie Institution

All diamonds are made up of carbon atoms arranged in a regular pattern. Some diamonds come directly out of the ground. Some are made in the lab.

To make the gems even harder, Hemley and his group first used a process called chemical-vapor deposition to add more carbon atoms to previously created artificial diamonds. They then cooked these new diamonds with lots of heat and pressure.

Temperatures in the cooker reached 2,000 degrees Celsius. The pressure equaled that experienced 150 kilometers below Earth’s surface. Under these conditions, the newly deposited diamonds became superhard.

The new diamonds were so hard, the researchers say, that they broke equipment worth about $10,000 while testing them. The testing machines couldn’t even dent or scratch some of the diamonds.

The scientists say that they can adjust the cooking conditions to make their diamonds not only superhard but also supertough, so the gems won’t crack or fracture easily.

Superhard diamond would be ideal as a coating for industrial tools and medical implants and as the stuff from which to make electronic devices that work under extreme conditions. Individual gems would also make gorgeous, durable jewelry.

The discovery of superhard and supertough diamonds could give new meaning to the old saying: Diamonds are forever.—E. Sohn

Going Deeper:

Weiss, Peter. 2004. Hard stuff: Cooked diamonds don’t dent. Science News 165(Feb. 28):131. Available at http://www.sciencenews.org/articles/20040228/fob1.asp .

You can learn more about diamonds at www.amnh.org/exhibitions/diamonds/ (American Museum of Natural History).

Now, scientists have found that the same part of your brain that gets busy when you’re actually dancing, skipping, jumping, or licking is also active when you silently read these action words.

The tissue in question is a strip that runs along the surface of your brain from one ear to the other. This strip is known as the motor cortex.

Scientists have long known that the motor cortex is responsible for controlling voluntary movement—any action you decide to do, such as kick, wave, or run. An involuntary movement is one you can’t control, such as the beating of your heart.

A new set of brain scans, obtained by scientists at the Medical Research Council in England, shows that the motor cortex becomes active even when people just read action words.

In the experiment, when a person read the word “lick,” the part of the motor cortex associated with movements of the tongue and mouth became active. An increased blood flow to that part of the brain signaled the activity. In another example, when a person read the word “jump,” blood flow increased in the part of the motor cortex connected with leg movements.

The results suggest that the motor cortex is involved not just in performing an action but also in helping people understand the meaning of the word for a given action.

It’s an unexpected finding because scientists had thought that a separate part of the brain processed language. It now appears that the brain has a more complicated way of interpreting words.

Whether you’re dancing or just reading about dancing, your motor cortex puts on its dancing shoes!—S. McDonagh

Going Deeper:

Bower, Bruce. 2004. The brain’s word act: Reading verbs revs up motor cortex areas. Science News 165(Feb. 7):83-84. Available at http://www.sciencenews.org/20040207/fob2.asp .

You can learn more about the brain’s motor cortex at faculty.washington.edu/chudler/functional.html (Neuroscience for Kids) and www.pbs.org/wgbh/aso/tryit/brain/ (PBS).

How did life forms get so complicated? Scientists at Pennsylvania State University may now have part of the answer. The secret ingredient could be the oxygen in Earth’s atmosphere.

Example of a plant cell, stained and viewed under a microscope.

The researchers found a relationship between the number of cell types in organisms and the quantity of oxygen in Earth’s atmosphere. The more oxygen there was, the more complex the organisms could become.

Early in Earth’s history, there was very little oxygen in the atmosphere. Only simple, single-celled organisms such as bacteria were around. Then, about halfway through Earth’s history (2.3 billion years ago), oxygen began to accumulate in the planet’s atmosphere. Around the same time, organisms with several types of cells appeared.

Researcher S. Blair Hedges says this happened because of an important change in the structure of cells. Some cells developed features called “mitochondria.” These are the little power plants inside cells. They use oxygen to generate energy.

Mitochondria were essential for organisms to become more complex. “It makes a lot of sense,” Hedges says, “because to have complex organisms, you need energy.”

Later, about 1.5 billion years ago, there was another change in cells that enabled organisms to become even more complex. Some cells developed features known as plastids. These are the parts of cells that enable plants to produce oxygen through photosynthesis.

The plastids boosted the amount of oxygen in Earth’s atmosphere. With more oxygen available, mitochondria could generate more energy.

Hedges and his colleagues estimate that organisms with up to 10 cell types emerged with the help of plastids. And the numbers kept growing. By 1 billion years ago, organisms with up to 50 cell types had appeared, the researches say.

Fossils had suggested that a big jump in the complexity of organisms took place 600 million years ago. If the estimates by Hedges and his colleagues are correct, life actually started on the road to complexity a lot earlier.—S. McDonagh

Going Deeper:

Travis, John. 2004. Gassing up: Oxygen’s rise may have promoted complex life. Science News 165(Feb. 7):85. Available at http://www.sciencenews.org/20040207/fob5.asp .

You can learn more about animal and plant cells at www.enchantedlearning.com/subjects/plants/cell/ (Enchanted Learning) and www.cellsalive.com/toc.htm (Cells Alive!).

Now, researchers at the companies Philips and E Ink have taken another step toward greater convenience. It’s a new type of electronic paper that displays words and pictures, just like your computer monitor. But it’s as thin as a sheet of regular paper. You can roll it up, fold it, or bend it. If you drop it, don’t worry. It won’t break.

Future electronic displays could look and feel more like paper.

Polymer Vision/Philips

The electronic paper has two main layers. The top layer is a plastic film that has tiny bubbles containing two types of ink, black and white. The bottom layer contains a network of tiny electronic circuits. These circuits are made out of a special type of plastic that conducts electricity.

How do these two layers work together to display a picture or words? First, the black and white inks have opposite electrical charges. When a particular voltage is applied to a bubble, the white ink rises to the top and the black ink sinks to the bottom, where you can’t see it. And if a different voltage is applied, the opposite happens. The black ink rises while the white ink lays low.

Applying different voltages by way of the circuitry below the ink layer organizes the ink into various patterns, such as words and pictures. By switching the voltage pattern, the electronic-paper display can change a few times per second.

The scientists who developed the electronic paper claim that their version is the thinnest, most flexible yet. Previous versions of electronic paper were made with a thin sheet of glass, which was fragile and rigid.

Bas Van Rens at Philips in the Netherlands says that, within a couple of years, you could be using electronic paper to check your e-mail or to surf the Internet. When you’re finished, you’d roll up your sheet of e-paper and tuck it away in your back pocket.—S. McDonagh

Going Deeper:

Goho, Alexandra. 2004. Flexible e-paper: Plastic circuits drive paperlike displays. Science News 165(Jan. 31):67. Available at http://www.sciencenews.org/20040131/fob1.asp .

Sohn, Emily. 2003. Electronic paper turns a page. Science News for Kids (Dec. 3). Available at http://www.sciencenewsforkids.org/articles/20031203/Feature1.asp .

Sohn, Emily. 2003. Opening a window on video paper. Science News for Kids (Oct. 1). Available at http://www.sciencenewsforkids.org/articles/20031001/Note2.asp .

You can learn more about electronic paper and ink at computer.howstuffworks.com/e-ink.htm (How Stuff Works) and www.media.mit.edu/micromedia/elecpaper.html (MIT Media Laboratory).

Scientists have just discovered that these deaths occur because the vultures are getting an accidental dose of medicine from the cattle meat. Farmers had given a drug to their livestock to heal the animals. To vultures, however, the drug turned out to be poisonous.

Oriental white-backed vultures make short work out of an animal carcass.

M. Virani

Finding the cause of the vultures’ deaths was like solving a mystery. At first, researchers thought the birds might have been dying of some mysterious plague.

Veterinarian J. Lindsay Oaks at Washington State University examined the internal organs of some dead birds to check for signs of disease. No disease. Instead, Oaks discovered that the birds’ kidneys had failed—not due to disease but due to poisoning.

Scientists already know that certain chemicals, such as the metal cadmium, are harmful to birds’ kidneys. But in their tests on the vultures, Oaks and his colleagues found no traces of cadmium or other familiar, harmful substances.

Next on the scientists’ list of suspects were any drugs used to treat livestock. The researchers checked to see what drugs farmers in the area used. They noticed one drug on the list known to hurt birds’ kidneys if the birds eat something with the drug in it. The culprit is called “diclofenac,” a veterinary medicine used by farmers in Pakistan and India to shrink swellings.

Losing the vultures could have all sorts of unwanted side-effects. With fewer vultures around to devour animal carcasses, there’s less competition for food—allowing the number of foxes to increase. The increase in the fox population has led to the spread of rabies. It’s an example of the complex chain of unexpected effects that can occur in nature.

The vultures are useful to farmers, too. When an animal dies, a farmer can leave the carcass out in the open for vultures to dispose of. Without vultures, farmers would have to find new ways of dealing with waste carcasses.

The researchers say the vultures might recover if the farmers stopped using the drug. But that might not be so easy for the farmers.

The vultures don’t have much time, though. Rick Watson of the Peregrine Fund in Idaho claims that if farmers don’t do something, three species of vulture will die out within 5 years.—S. McDonagh

Going Deeper:

Milius, Susan. 2004. Vanishing vultures: Bird deaths linked to vet-drug residues. Science News 165(Jan. 31):69-70. Available at http://www.sciencenews.org/20040131/fob6.asp .

You can learn more about vultures in Pakistan at edu.iucnp.org/newbirds/pstory2.htm (World Conservation Union/IUCN).

It can take much longer for debris to settle when an avalanche happens beneath the ocean. Underwater landslides can keep going and going—even along surfaces that are nearly flat. These huge, rolling masses of clay and silt sometimes wipe out plant and animal life over vast areas of the seafloor.

What keeps ocean avalanches on the move?

In 1995, a large part of this bluff in the Sleeping Bear Dunes National Lakeshore suddenly disappeared beneath the waters of Lake Michigan in a huge landslide. U.S. Geological Survey scientists found a thick blanket of debris from the slide extending more

USGS

Norwegian scientists have used computers to help solve the puzzle. They figure that undersea avalanches travel far and fast because the moving sediment rides on a thin layer of water trapped between the sediment and the seafloor. This water layer cuts down the friction, letting the sediment keep sliding for long distances, sometimes at high speed.

Anders Elverhøi of the University of Oslo and his coworkers described their results in this month’s Journal of Geophysical Research—Oceans.

Something similar can happen to cars and trucks in wet weather. When traveling along a wet road, a car can lose its grip on the asphalt—making the car go into an uncontrollable slide. This loss of traction is known as “hydroplaning.” It’s caused by a layer of water between the tire and the road.

Hydroplaning might explain the size and reach of a massive avalanche known as the Storegga slide. It took place in the Norwegian Sea about 8,000 years ago. Enough sediment to make up several mountains broke free in that avalanche, and some of slid nearly 500 kilometers.

And, in a 1929 slide just south of Newfoundland, 300 to 700 cubic kilometers of sediment sped across the seafloor at nearly 80 kilometers per hour, snapping several transatlantic communication cables.

Crabs, shrimp, and Nemo, get out of the way! Once an underwater landslide gets going, there’s no stopping it until it’s moved a long, long way.—S. McDonagh

Going Deeper:

Perkins, Sid. 2004. Scooting on a wet bottom: Some undersea landslides ride a nearly frictionless slick of water. Science News 165(Jan. 23):84. Available at http://www.sciencenews.org/20040124/fob7.asp .

You can learn more about the coastal landslide at Sleeping Bear Dunes, Michigan, at wrgis.wr.usgs.gov/fact-sheet/fs020-98/ (U.S. Geological Survey).

Additional information about landslides is available at interactive2.usgs.gov/learningweb/
explorer/topic_hazards_landslides.asp (U.S. Geological Survey).