Putting on sunscreen and wearing a hat helps prevent sunburn on a sunny day.

Katie Wiley

When I was younger, I played in the sun without worry. Now that I’m 30, I realize how important it is to protect myself. That’s because the same ultraviolet (UV) rays that make us warm and tan also harm the cells in our skin. You can’t see the damage when you’re young, but its effects often show up decades later.

After years of tanning, the skin gets wrinkled, leathery, and, worst of all, prone to skin cancer. The disease is directly linked to UV exposure, says Mandeep Kaur. She’s a dermatologist at Wake Forest University School of Medicine in Winston-Salem, N.C.

As young people flock to beaches and tanning salons, skin cancer is becoming more common and appearing at younger ages, Kaur says.

“We used to see only older and middle-aged people with skin cancer,” she says. “These days, we see people in their 20s or 30s.”

Tanning dangers

Kaur and her colleagues reviewed a large number of studies about skin cancer and UV light. The disease, they found, is the most rapidly growing cause of cancer deaths in the United States.

Even so, doctors rarely warn their young patients about the dangers of tanning.

What your doctor should tell you is that your skin is the largest organ in your body. It keeps your stomach and other organs from spilling out. And it keeps germs from getting in. Skin allows you to feel pain, heat, cold, and other sensations. And through sweat, it rids your body of extra water and salt. Can you imagine life without it?

A desert isn’t the only place where it’s essential to put on sunscreen for protection against the sun’s ultraviolet rays. Even on a cloudy day, ultraviolet rays can still cause sunburn.

Annie Feidt

Although our skin works hard to protect us, few people work to protect it. The sun’s UV rays are the biggest threat because they damage the genetic material DNA in the cells of your skin. Damaged, or mutated, cells are supposed to kill themselves, but sun-damaged skin cells eventually become cancerous and multiply out of control. They produce abnormal growths called tumors.

The tricky thing is that this process can take 30 or more years to become evident.

“It’s surprising how long it takes,” says Meenhard Herlyn, a tumor biologist at the Wistar Institute in Philadelphia. “Even if kids have big, blistering sunburns every summer, they’re fine while they’re kids.”

Skin cancer

There are two categories of skin cancer. Nonmelanoma tumors develop in the outermost layer of skin. They usually appear on the head, neck, and other exposed areas. There are about 1 million new cases of nonmelanoma in the United States each year, according to the American Cancer Society. Doctors can easily remove most of these cancers if they catch them early.

The second type of skin cancer is melanoma. It is less common than nonmelanoma cancer. There are only 60,000 new cases a year in this country. However, melanoma is far more likely to spread to other organs and become deadly. Melanoma affects the cells in your skin that produce pigment, or color, that makes you tan. These cells are most active when you’re young, so getting sunburns during childhood puts you at especially high risk.

Melanoma is a cancer of the skin’s pigment cells. It appears as a new spot or an existing spot that changes color, size, or shape. It usually has an uneven, smudgy outline and appears as an irregular mix of colors.

Department of Dermatology, Uniformed Services University of the Health Sciences

“If you have more than five blistering sunburns while you’re under 15,” Herlyn says, “it increases your risk for getting melanoma three- to fivefold.”

All types of skin cancer occur most often in people who have red or blonde hair, freckles, or pale skin that burns easily. People with naturally dark skin rarely get skin cancer.

Skin cancer treatment usually involves surgery to remove damaged cells, but new approaches are in the works. The most promising leads come from studies of internal signals that cancer cells use to stay alive.

“We’re slowly getting to know what makes melanoma cells tick,” Herlyn says. If researchers can block the important signals with drugs, the bad cells might die.

Herlyn’s coworkers, for example, are working on a melanoma vaccine that would help a patient’s immune system recognize and attack skin cancer cells. Other scientists are creating lotions that could help cells repair themselves.

Sunning safely

The best way by far to fight skin cancer is to not get it in the first place. That doesn’t mean you have to stay inside all the time. You just have to learn how to be sun savvy.

Putting on sunscreen is essential before surfing and other outdoor activities.

E. Sohn

The American Academy of Dermatology recommends wearing sunscreen (SPF 15 or higher), sunglasses, wide-brimmed hats, long-sleeved shirts, and long pants whenever possible. Avoid direct sunlight when it’s at its strongest—between 10 a.m. and 4 p.m. Be careful near snow, sand, and water, which create strong reflections. And avoid tanning beds.

These steps may seem extreme if you live in a place where tanned skin is considered attractive. But if you want a wrinklefree, cancerfree future, it may be time to think about the cost of “beauty” that doesn’t last.

“If you want to be healthy,” Kaur says, “you have to have good skin.”

Going Deeper:

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Word Find: Skin Cancer

Comments:

I’m very good with sunscreen and all that, but if people don’t want us to get skin cancer then why do they price it so high?—Stephanie, 12

Now, scientists have uncovered a clue to ancient spider life in a piece of fossilized tree resin (called amber) that is 110 million years old. The Spanish amber contains several strands of an ancient spider web, captured insects included.

Strands of silk, which are too small to be seen in this photo, are indicated by dark lines superimposed on the amber. Also caught in the amber are a fly (top center) and a mite (left inset). The other inset (right) shows glue droplets used to capture prey

© Science

The team of researchers found pieces of at least 26 strands of silk in the amber. Most of the strands are either straight or slightly curved.

The longest strand is about 5.7 millimeters (0.2 inch) in length. Most strands are between 0.6 and 1.9 micrometers wide. (A micrometer is one-millionth of a meter.) The amber is about 18 millimeters (0.7 inch) long.

In the webs of modern orb-web spiders, long strands of silk connect at a center point, like the spokes of a bicycle wheel. Sticky, insect-catching threads then connect the long spoke strands, forming rings that spiral out from the center.

An orb web made by a spider from Palo Alto, Calif.

Photo courtesy of Mark Chappell

Some of the amber-preserved strands form a similar pattern, which suggests that the ancient spider belonged to the orb-web family. Further supporting this view, the specimen holds two drops of the “glue” that these spiders use to add stickiness to their webs.

A wasp trapped in an ancient spider web.

© Science

It makes sense that the spider’s web-weaving strategy has remained essentially the same for millions of years. After all, it seems to work. Also caught in the amber were a wasp, a fly, and a mite. Orb-web spiders still eagerly devour these insects today.—E. Sohn

Going Deeper:

Perkins, Sid. 2006. Sticky subjects: Insights into ancient spider diet, kinship. Science News 169(June 24):390. Available at http://www.sciencenews.org/articles/20060624/fob7.asp .

LabZone
Spy on a Spider
http://www.sciencenewsforkids.org/articles/20040519/LZActivity.asp

ScienceFairZone
Tobacco Smoke and Spiders
http://www.sciencenewsforkids.org/articles/20040317/ScienceFairZone.asp

The relationship, however, is not so simple. The fish that do the cleaning actually prefer to dig a little deeper, taking a little nip of the tasty goo covering the skin instead of just skimming off the parasites. New studies now show that coral reef fish pay attention to how the cleaners do their job, preferring to visit those cleaner fish that are less likely to bite.

As small cleaner fish feed on skin parasites of a bigger fish, they may be building their reputations as good workers.

I. Burkhardt

Previous studies had found that, in the wild, cleaner fish seem to react to being watched by taking good care of their customers and biting them less often.

The idea that animals show off their good behavior and earn rewards from those who see it “has been floating around,” says behavioral ecologist Lee Alan Dugatkin of the University of Louisville in Kentucky. “This is the strongest evidence so far that it’s really happening in nature.”

In one set of tests, researchers used an aquarium with separate sections. In the middle section, they placed a type of coral reef fish called a bridled monocle bream. In the section at each end of the tank, the researchers placed a cleaner fish.

Then, the researchers presented each cleaner fish with a visitor fish to clean. One cleaner got a visitor that was already clean. The other got a visitor that was smeared with delicious prawns.

The monocle bream in the middle could see the cleaner fish, but the cleaners couldn’t see the monocle bream. As expected, the first cleaner mostly ignored its already-clean visitor. The second, on the other hand, munched and munched.

In 28 trials, the researchers found, the monocle bream in the center section tended to hover near the cleaner fish that was hard at work—almost as if it were waiting its turn with that cleaner.

In another study, the scientists wanted to see what would happen when the cleaners had an audience. They stocked two plates with both ho-hum fish-food flakes and delectable prawns. As long as the cleaner nibbled the flakes, the researchers left the second plate nearby—as if it were a waiting customer. If the cleaner fish gulped a prawn, though, the researchers snatched away the second plate.

The fish ate more of the uninspiring flakes when the second plate was nearby than when there was only one plate.

This mimics the situation in the real world, the researchers say. On a reef, a cleaner fish that takes a juicy bite out of a visitor’s skin could cause an upset that would drive away a waiting customer.—E. Sohn

Going Deeper:

Milius, Susan. 2006. Fishy reputations: Undersea watchers choose helpers that do good jobs. Science News 169(June 24):388. Available at http://www.sciencenews.org/articles/20060624/fob3.asp .

You can learn more about cleaner fish at www.amonline.net.au/fishes/fishfacts/fish/ldimidiatus.htm (Australian Museum) or www.soc.soton.ac.uk/GDD/hydro/atmu/ecology/chapter6/3.html (National Oceanography Centre, Southampton).

Kelydra, 17, lives in Parkersburg, W.Va. Nearby, a DuPont chemical plant makes a variety of products, including the nonstick material Teflon. Tiny amounts of an ingredient used to produce Teflon have ended up in the area’s water supply. Lab tests have shown that this chemical, known as APFO, is toxic and may cause cancer in animals.

Kelydra Welcker collects a water sample from the Ohio River.

Courtesy of Kelydra Welcker

The water that comes out of Parkersburg’s faucets looks and tastes fine, but many people worry that drinking it will hurt their health.

Instead of just worrying about the problem, Kelydra took action. She invented a way to detect and help remove APFO from drinking water. And she has applied for a patent on the process.

This science project earned Kelydra a trip to the 2006 Intel International Science and Engineering Fair (ISEF), held last May in Indianapolis. About 1,500 students from around the world competed for prizes at the fair.

Kelydra at the Intel International Science and Engineering Fair in Indianapolis.

V. Miller

“I want to clean the environment,” says Kelydra, a junior at Parkersburg South High School. “I want to make the world a better place for our children.”

Mosquito studies

Kelydra began her research on toxic substances when she was in seventh grade. She wondered how pollution might affect animals in her area’s streams and rivers.

Scientists had already learned that chemicals called steroids can alter fish behavior. As part of her seventh-grade science project, Kelydra looked for similar effects on mosquitoes.

A female mosquito.

Courtesy of Kelydra Welcker

She focused on the effects of estrogen and several other steroids that are known as endocrine disruptors. The body’s endocrine system produces chemical substances called hormones. Hormones regulate growth, the production of eggs in females, and other processes essential for life.

As a result of her early research, Kelydra discovered that endocrine disruptors affect the rates at which mosquitoes hatch and that they also change the buzzing sounds that mosquitoes make when they beat their wings. That discovery earned her a spot as a finalist in the 2002 Discovery Channel Young Scientist Challenge (DCYSC).

At DCYSC, Kelydra learned that scientists have to speak clearly if they want to persuade people that their research is significant.

“It’s important to be able to talk in sound bites, short and sweet,” she says, “so that people can put the message in their heads.”

Kelydra analyzes the sounds of a mosquito’s beating wings.

Courtesy of Kelydra Welcker

Another research effort involving mosquitoes brought Kelydra to the 2005 ISEF in Phoenix, Ariz. At this event, she won a $500 prize for the best use of photography in a science project.

Chemical effects

This year, Kelydra focused on APFO, the chemical that has been worrisome to her neighbors in Parkersburg.

APFO is short for ammonium perfluorooctanoate, which is also sometimes called PFOA or C8. Each molecule of APFO consists of 8 carbon atoms, 15 fluorine atoms, 2 oxygen atoms, 3 hydrogen atoms, and 1 nitrogen atom.

APFO is a building block in the production of Teflon. It’s also used in the manufacture of water- and stain-resistant clothing, fire-fighting foams, and other products. And it can form from substances used to make grease-resistant fast-food packaging, candy wrappers, and pizza-box liners.

The chemical has shown up not only in drinking water but also in the bodies of people and animals, including those living in the Parkersburg area.

To illustrate the potential dangers of APFO, Kelydra turned again to mosquitoes. She bred some 2,400 mosquitoes in her kitchen and timed their life cycles.

Mosquito pupae just after hatching.

Courtesy of Kelydra Welcker

Her results suggested that when APFO is in the environment, mosquitoes hatch sooner than they do normally. So, more generations of mosquitoes end up living and breeding each season. With more mosquitoes around, diseases that they carry, such as West Nile virus, can spread more quickly, Kelydra says.

Water treatment

To help her neighbors and to improve the environment, Kelydra wanted to find a way to detect and measure APFO in water. She sought to create a test that was simple and inexpensive so that people could analyze water coming out of their home taps.

Kelydra knew that when you shake water contaminated with relatively high amounts of APFO, the water gets foamy. The more APFO in the water, the foamier it gets. When APFO gets into drinking water, however, the concentrations are usually too low to create foam.

A higher concentration of APFO in water increases the height of foam created when the sample is shaken.

Courtesy of Kelydra Welcker

To increase the concentration of APFO in a water sample to levels at which it could be detected by foaming, Kelydra used an apparatus called an electrolytic cell. One of the cell’s electrodes worked like an electrically charged wand. It attracted APFO. This meant that the amount of APFO in the water decreased.

At the same time, she could carefully rinse off the wand, creating a new solution with a higher concentration of APFO. When she shook the new solution, foam formed.

This apparatus, consisting of a dry cell and two electrodes, allowed Kelydra to remove much of the chemical APFO from contaminated water.

Courtesy of Kelydra Welcker

“It worked like a dream,” Kelydra says.

The technique can do more than detect APFO in water, she says. It might also help people remove the chemical from their water supply.

Next year, Kelydra plans to create a system that will allow people to purify several gallons of water overnight. She’s enthusiastic about the idea. And, on the basis of her experiences so far, she’s confident that it will work.

Going Deeper:

Additional Information

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Scientist’s Notebook: Mosquito Research

Word Find: APFO

You’d think it would be hard to lose an animal with so many legs, but that’s exactly what happened to this particular millipede. No one had seen one for 79 years until researchers recently spotted the critter in San Benito County, California, which is located several hours south of San Francisco.

A rare California millipede may be the world’s leggiest species, but it moves slowly and grows barely as long as an entomologist’s thumb.

© Paul Marek and Jason Bond, East Carolina University

There are more than 1,000 species of millipedes worldwide. Distantly related to lobsters and shrimp, these animals have four legs per body segment. They don’t bite, sting, or carry diseases. Luckily for many other creatures, they spend a lot of time eating dead leaves and recycling the nutrients into the soil.

In contrast, centipedes have two legs per body segment, and some have a dangerous bite.

I. plenipes was first observed in 1926 by a scientist who was one of the pioneers of millipede studies in North America. Later, when other specialists scoured the same small area in California looking for these millipedes, they came back empty-handed.

Part of the problem is that the leggy creatures are hard to see. Despite their many legs, adults measure less than 3.4 centimeters (1.3 inches) long and about half a millimeter (0.02 inch) wide.

“It’s pretty hard to immediately tell the difference between this tiny threadlike thing and a [plant] root hair,” says millipede expert Paul Marek of East Carolina University in Greenville, N.C.

Last year, Marek and his brother visited the area where I. plenipes had originally been found. They came around Thanksgiving during the rainy season, when millipedes, which like wet conditions, are more likely to crawl from their underground lairs to the surface. After about an hour of searching, they spied a moving squiggle. It was a living I. plenipes.

Marek says he was so excited that he was probably close to hyperventilating.

Over several more visits, the brothers and a colleague collected 12 millipedes (leaving at least as many behind). The adults had between 318 and 666 legs.

The millipede’s legs are tiny. This magnified image shows that four legs are attached to each body segment.

© Paul Marek and Jason Bond, East Carolina University

Females usually have more legs than males do, Marek says, and the millipedes probably grow additional legs as they get older.

The rediscovery of I. plenipes is wonderful news, says millipede expert Robert Mesibov of the Queen Victoria Museum and Art Gallery in Launceston, Tasmania. The island of Tasmania by itself has more than 160 millipede species.

It’s striking that I. plenipes appears to live within just one 0.8-square-kilometer patch of land. “If we’re serious about conserving biodiversity,” Mesibov says, “we need to pay attention to tiny natural areas.”

The only other millipedes that belong to the same family as I. plenipes live in Southeast Asia. That means these millipedes must have an unusual family history. The ones we see today may trace their family tree back to a time before today’s continents had split apart.—E. Sohn

Going Deeper:

Milius, Susan. 2006. Leggiest animal: Champ millipede located after 79-year gap. Science News 169(June 10):357-358. Available at http://www.sciencenews.org/articles/20060610/fob6.asp .

You can learn more about millipedes at www.smm.org/boghopper/Millipede.html (Science Museum of Minnesota) and en.wikipedia.org/wiki/Millipede (Wikipedia).

To compare centipedes, millipedes, and pill bugs, go to www.backyardnature.net/1000legs.htm (Backyard Nature) and www.myriapoda.org/ (East Carolina University).

Science project idea: What types of millipedes are found in your area? Where are they most likely to be found? How would you raise or care for millipedes?

Now, scientists have figured out how a tree frog manages to keep its grip.

A tree frog’s toes can grip both wet and dry surfaces.

Thomas Endlein

A tree frog’s foot is covered with a wet film. This layer of fluid led scientists to think that the frog’s wet toe pads cling to a surface by the same force that makes a damp piece of paper stick to a window. But this didn’t explain how a frog could walk on something wet, such as a rock in a stream or a branch in the rain.

To answer this question, Walter Federle of the University of Cambridge in England and a team of scientists took pictures of tree frogs walking on glass. By magnifying the pictures and making measurements, the researchers found that the wet layer on a frog’s foot is very thin. In some places, there’s no film at all.

It turns out that a tree frog has tiny bumps on the bottom of its feet, almost like soccer cleats. Because the wet film is so thin, these bumps poke through and stay dry, giving a tree frog better traction when climbing slippery surfaces.

A tree frog’s toe pads also have little channels along which fluid can flow. On wet surfaces, the channels funnel away extra fluid. On dry or uneven surfaces, they bring additional fluid to the pads, allowing the frog to cling more tightly or even hang upside down.

A tree frog’s toe pad (upper inset) consists of six-sided skin cells (lower inset) that are covered with cleat-like bumps (bottom).

Thomas Endlein

A gecko’s feet have inspired a new type of adhesive tape (see “Sticking Around with Gecko Tape”). If engineers can figure out how to imitate a tree frog’s foot, we might someday have car tires that stick to the road even when the road’s wet.—E. Jaffe

Comments:

I think this article includes a safety issue. If engineers
could find a way to make tires stick to the road on wet, rainy days, then
more cars could stay on the road and there would be fewer accidents. I hope
it happens soon, because there was just a huge accident in my area. Hope it
helps!—Emily, 11

Going Deeper:

Jaffe, Eric. 2006. Walking on water: Tree frog’s foot uses dual method to stick. Science News 169(June 10):356. Available at http://www.sciencenews.org/articles/20060610/fob3.asp .

McDonagh, Sorcha. 2004. Gooey secrets of mussel power. Science News for Kids (Jan. 21). Available at http://www.sciencenewsforkids.org/articles/20040121/Note2.asp .

______. 2003. Sticking around with gecko tape. Science News for Kids (June 11). Available at http://www.sciencenewsforkids.org/articles/20030611/Note2.asp .

Sohn, Emily. 2006. Microbe superglue. Science News for Kids (May 3). Available at http://www.sciencenewsforkids.org/articles/20060503/Note2.asp .

______. 2005. Geckos’ sticky feet clean themselves. Science News for Kids (Jan. 12). Available at http://www.sciencenewsforkids.org/articles/20050112/Note3.asp .

______. 2003. How a gecko defies gravity. Science News for Kids (Nov. 19). Available at http://www.sciencenewsforkids.org/articles/20031119/Feature1.asp .

Science project idea: Compare the adhesive strength of different kinds of tape (see http://www.sciencenewsforkids.org/articles/20060426/LZActivity.asp ).

In my fascination with fireflies, I’m not alone.

A firefly rests on white clover.

iStockphoto.com

“When kids see fireflies, they commonly ask one question: ‘Why do they light up?’” says entomologist Marc Branham of the University of Florida in Gainesville. “It’s the parents who ask: ‘How can fireflies actually produce light?’”

Scientists are shedding light on both questions.

And they have plenty of material to work with. Fireflies live on every continent except Antarctica. About 2,000 species are known to scientists, and many more probably remain to be discovered.

Different types of fireflies vary in how quickly they flash, how long the flashes last, and what color the flashes are.

“We’ve known for a long time that fireflies use different signals,” says Sara Lewis, an evolutionary ecologist at Tufts University in Medford, Mass. “Only in the past few years have we been able to decode some of the details of those flashes.”

Chemical light

Fireflies, deep-water fish, bacteria, and other organisms that produce their own light are said to be bioluminescent.

A firefly’s light is produced by a chemical reaction involving a special protein, a pigment called luciferin, and oxygen. The protein, named luciferase, acts as an enzyme, starting the chemical reaction that generates light.

Light-producing chemical reactions in a firefly’s abdomen cause certain cells on its underside to glow (right). The species shown in this illustration is Say’s firefly, one of about 175 known species of fireflies in the United States.

Scientific illustration by Arwin Provonsha, Purdue Department of Entomology

Most bioluminescent creatures simply glow. The flash of the firefly sets it apart. “The ability to turn light on and off with precise timing is much more rare,” Lewis says.

To make light, she says, a firefly’s brain sends a signal to the light organ in its abdomen, where the light-producing chemical reactions occur. A few years ago, Lewis and her colleagues discovered that the process also involves a gas called nitric oxide. It’s this gas that operates the insect’s on-off switch.

Scientists have also uncovered the genetic information, contained in a firefly’s DNA, responsible for producing luciferase.

Such discoveries about firefly biology have been especially exciting to medical researchers. They can implant the firefly’s light-producing gene into cells inside other animals. Then, by monitoring the glow, they can track those cells in the animals’ bodies.

These fruit flies contain some firefly DNA, which enables them to glow in the dark.

Steve A. Kay, Scripps Research Institute

By making cancer cells glow, for example, researchers can trace the effectiveness of a treatment. If all the glowing cells disappear, it’s a sign that the treatment may be working.

Mating signals

Other scientists are examining why fireflies flash. So far, it appears that fireflies flash for two reasons: to attract mates and to attract prey.

But not just any type of flash will do. One recent study found that in some firefly species, females prefer to mate with males whose flashes last the longest. In other species, females prefer males who flash the fastest.

Individual differences in flash length and speed are so slight that our eyes can’t detect them. But special instruments can detect the differences—and so can fireflies. Scientists can test this by flashing precise light patterns of their own and observing which ones female flies respond to by flashing in turn.

The firefly is a type of beetle. Found in New York State, this example is one of about 2,000 firefly species known worldwide.

© 2004 Joyce Gross

A closer look suggests why the ladies care how their men flash. Often, males that have the best chance of fathering lots of young also flash fastest or longest, Lewis’ group has found. So, it makes sense for females to pick the “flashiest” males.

Such studies give insights into the process of sexual selection, which describes how choosing mates helps drive evolution.

A firefly’s flash is similar to a cricket’s chirps and other types of animal mating signals. “It’s helpful to compare multiple types of signals across a lot of organisms to see if they evolved the same way because they’re obviously not produced the same way,” Branham says.

“We’ve found time and time again that lots of organisms arrive at the same answer by different routes,” he adds. “When we compare these patterns, it can tell us a lot about how life converges on the same solutions to the same problems.”

Declining numbers

Studying fireflies could also help protect them. No one has counted fireflies from year to year, but some experts worry that their numbers are declining.

A boy traps fireflies at twilight.

iStockphoto.com

“Every summer, a lot of people ask me why there are fewer fireflies out there than when they were kids,” Branham says. “I think when people realize there’s stuff to learn about fireflies in addition to the fact that they’re fun to watch and catch, maybe conservation will take a higher profile.”

You’d have to get over any fear of the dark that you might have if you want to be a firefly scientist. To observe them, you need to spend time outside at night. And if you turn on your flashlight, the fireflies shut off theirs.

Branham does much of his research in rain forests, and the work can be creepy.

“In tropical areas, there are a lot of poisonous snakes that are nocturnal,” he says. “Combine that with the necessity of not turning on your flashlight, and it’s a pretty intense experience.”

Still, the more you study fireflies, the more amazing they get, Lewis says.

“Learning about them enhances the mystery,” she says. “I’m still completely blown away by the fact that they’re doing this.”

Going Deeper:

Additional Information

Questions about the Article

Word Find: Fireflies

The tritare, a new type of musical instrument, uses a Y-shaped string anchored at three endpoints.

Samuel Gaudet, University of Moncton

Instead of having strings that stretch between two points, the tritare has strings that are attached to the instrument at more than two points. Picture, for example, a Y-shaped string, anchored at its three endpoints.

When played, the instrument produces an eerie sound that challenges the ears with complicated echoes and vibrations.

The tritare looks like a guitar with two extra necks. One of the necks has thin crossbars, or frets, that mark places where pushing on strings creates desired pitches. The other two necks are unfretted.

The tritare uses three string segments that form a Y shape (left). The instrument’s inventors are exploring sounds generated by other string networks as well (right).

Samuel Gaudet, University of Moncton

Plucking, strumming, or bowing a normal guitar string creates mathematically related sounds called harmonic overtones. For the most part, a string vibrates at a specific, standard rate (or frequency), say 440 times per second, which is the note A. But it also vibrates at twice that rate, creating a sound called the second harmonic. The string’s vibration at three times the basic rate is called the third harmonic, and so on.

Playing the tritare generates harmonic overtones, but it also creates sounds that are nonharmonic. Nonharmonic frequencies fit in between the harmonic frequencies.

Harmonics sound simple, familiar, and pleasant to our ears. Nonharmonics, which are often produced by gongs, bells, and other percussion instruments, sound more complicated. If played correctly, the tritare can produce many nonharmonics at once.

The researchers, who are at the University of Moncton in New Brunswick, say that the tritare’s sound is beautiful and has lots of potential for musical expression.

“Sounds which are richer and less safe harmonically . . . provide inspiration and ways to musically express different things,” says Samuel Gaudet, one of the inventors.

Other researchers are more skeptical.

“To my ears [the tritare] just sounded like a badly out-of-tune instrument,” says acoustics specialist Bernard Richardson of Cardiff University in Wales.

Someday, more complicated string instruments might challenge your sense of music even more. Will you be a fan? Check the following Web page, where you’ll find some samples of such sounds to help you decide: www.acoustics.org/press/151st/Leger.html.—E. Sohn

Going Deeper:

Weiss, Peter. 2006. String trio: Novel instrument strums like guitar, rings like bell. Science News 169(June 3):342. Available at http://www.sciencenews.org/articles/20060603/fob7.asp .

For additional information about the tritare, go to www.acoustics.org/press/151st/Leger.html (Acoustical Society of America).

Science project idea: Instead of Y-shaped strings, try other patterns. How does the string geometry affect the sounds created by a musical instrument?

The potential for misery might get even worse. A new study suggests that rising levels of the gas carbon dioxide in the atmosphere could make poison ivy grow faster and become more toxic.

Poison ivy grows unusually fast when carbon dioxide in the atmosphere reaches levels expected in forests by about the year 2050.

J. Blanchard

“Rising carbon dioxide can favor pests and weeds, those plants we’d least like to see succeed,” says climate-change ecologist Bruce Hungate of Northern Arizona University in Flagstaff.

Large doses of carbon dioxide (CO₂) get into the air when people burn coal, oil, natural gas, and other fossil fuels. Carbon dioxide is a greenhouse gas. As it accumulates, the atmosphere traps more heat, and Earth’s climate warms up.

Plants need CO₂ to grow. To test whether extra CO₂ in the environment leads to extra plant growth, scientists have set up circles of pipes as high as treetops around the world. These pipes spit out either regular air or extra CO₂ over a patch of ground. As a result, researchers can compare how plants respond to different atmospheric conditions.

For 6 years, scientists monitored plants that grew near some of these pipes in a Duke University pine forest. They found that, with about 50 percent more CO₂ around, poison ivy plants were able to make more food and use water with greater efficiency.

Poison ivy plants that got the CO₂ boost produced the same amount of toxic oil, called urushiol, as regular air-bathed plants. With extra CO₂, however, more of the urushiol was in a particularly toxic form and more likely to cause rashes.

Poison ivy’s success in the presence of extra CO₂ is just one example of how climate change might alter the dynamics of forest ecosystems, scientists say.

With more poison ivy around, it might also become harder to enjoy being in the woods. Lead researcher Jacqueline E. Mohan, for example, had never developed a rash from poison ivy before she started the study. “I get it now,” she says.—E. Sohn

Going Deeper:

Milius, Susan. 2006. Pumped-up poison ivy: Carbon dioxide boosts plant’s size, toxicity. Science News 169(June 3):339. Available at http://www.sciencenews.org/articles/20060603/fob1.asp .

Additional information about research in the Duke Forest can be found at www.env.duke.edu/forest/ (Duke University).

To learn more about the effects of poison ivy, go to kidshealth.org/kid/health_problems/skin/poison_ivy.html (KidsHealth for Kids).

Sohn, Emily. 2006. Plant gas. Science News for Kids (Jan. 18). Available at http://www.sciencenewsforkids.org/articles/20060118/Note2.asp .

______. 2005. Arctic algae show climate change. Science News for Kids (March 9). Available at http://www.sciencenewsforkids.org/articles/20050309/Note2.asp .

______. 2004. A change in climate. Science News for Kids (Dec. 8). Available at http://www.sciencenewsforkids.org/articles/20041208/Feature1.asp .

______. 2003. Slower growth, greater warmth. Science News for Kids (April 30). Available at http://www.sciencenewsforkids.org/articles/20030430/Note2.asp .

Science project idea: Grow different plants in chambers with higher-than-normal levels of carbon dioxide. What effect do elevated levels of carbon dioxide have on how different plants grow?