Tabla de contenidos para Mar-Apr-10 en Science Illustrated

BIOLOGYScientists have long been aware that snakes push off laterally against objects like rocks and branches to help them move. Their movement over surfaces such as sand and paved roads with no helpful objects has been more of a mystery. Now research from New York University and Georgia Tech is explaining how friction generated by a snake's scales, combined with almost imperceptible shifts in its body weight, helps the reptile move forward on flat ground, and possibly on any terrain. Researchers anesthetized snakes and then measured the resistance created by sliding them in different orientations on a tilted board. When the board was covered with a piece of fabric, sideways movement resulted in twice as much friction compared with forward sliding (friction was calculated based on the angle of the…

1 How do the brain's connections form? Developmental neurobiologist Jeff Lichtman tracks how the brain's wiring changes during development. 2 What do the brain's circuits look like? Neurobiologist Winfried Denk maps the activity and structure of the brain's neuronal circuits. 3 How are the different regions of the brain networked? Imaging scientist Van Wedeen tracks the connections between different areas of the brain. Ever since individual nerve cells were first imaged in the late 1800s, biologists have tried to understand how these cells give the brain its incredible abilities. We now know quite a bit about nerve cells, or neurons, and how they generate and transmit signals. We can also pinpoint the roles played by many regions of the brain. But the more we learn, the clearer it becomes that…

A factory in the southeastern Mexican city of Tuxtla Gutierrez is hard at work churning out an unusual product: bugs. Sterile screwworm flies (Cochliomyia hominivorax) have been bred here since 1976 as part of a U.S. Department of Agriculture eradication program. In the wild, female screwworm flies lay as many as 400 eggs near open wounds on animals. The maggots that develop use two needle-sharp, hook-shaped mouthparts to burrow deep into the animal's flesh. The swarm of screwworms can consume so much tissue that the victim is virtually eaten alive from within. Screwworm flies, which are found in most tropical regions around the world, were first documented on Devil's Island off the coast of French Guiana in 1858. From there they spread throughout the warmer regions of the Americas, and…

The Amazon and its tributaries begin in the Andes mountains, and some of them are white-water rivers, which are full of nutrients. In the rainy season, these rivers overflow their banks and deposit their minerals on the floodplains, fertilizing the soil and making it suitable for agriculture. Every year during high water, 3 to 4 percent of the Amazon basin lies underwater. This is an area almost twice the size of England. After the rainy season, during the six months until the next floods would submerge their fields, the natives used the land that was covered with silt to raise crops like corn, rice and cassava. During the approximately six months of high water each year, fishing became more difficult because the area of distribution of the fish became wider.…

Geography: Canada Botany: Fern Sports: Bobsled Zoology: Penguin Beverages: Tea History: 1962 1. 3 × 4 − 9 + 7/5 = 2 2. See diagram. The marked tiles are colored dark blue. 3. Seven bees. See the diagram for one of a few possible solutions. 4. 10 paths to E. The diagram shows the number of paths to each circle. Each number is the sum of the numbers in the circles that lead to it. 6 + 4 = 10, so there are 10 paths to E. 5. 12. The numbers in the second column can be obtained from the numbers in the first column by rearranging them and changing one “b” to a “c.” It follows that “c” must be 4 less than “b.” Similarly, the numbers in the…

Two recent studies are adding weight to a decade-old theory that global cooling played a big part in the evolution of our large brains. Human brain activity generates a tremendous amount of heat, which the body must release to prevent overheating. Ten years ago, biologists David Schwartzman and George Middendorf of Howard University hypothesized that prehistoric brain size was constrained by a hot climate. Humans probably weren't able to develop big brains until the environment was cool enough. The researchers posited that a cooling trend over the past 50 million years allowed for increases in human brain size. Recent work by climate researcher Axel Kleidon of the Max Planck Institute for Biogeochemistry in Germany supports a theory of temperature-restricted development. According to his climate models, both temperature and carbon dioxide…

At the bottom of the Mediterranean Sea off the coast of the French port of Toulon, at a depth of just over 1.5 miles, sits a most unusual telescope. It is impossible to see daylight there, let alone anything in the night sky. Yet this is the home of a powerful optical device. Called ANTARES (Astronomy with a Neutrino Telescope and Abyss environmental RESearch), it studies the cosmos by staring down, not up. Its detectors face the center of the planet and scan for traces of some incredibly small and mysterious particles called neutrinos. Studying the data from these elusive cosmic visitors could give astronomers a new perspective on some of the most violent events in the universe. Neutrinos are tiny juggernauts, barreling through walls, mountains, planets and stars as…

Although we live inside it, astronomers know less about the Milky Way than they do about galaxies that are many more light-years away. In the midst of our galaxy's collection of roughly 400 billion stars, we aren't able to get a clear view of its structures. The Spitzer Space Telescope, launched in 2003, is changing that. In other galaxies, seeing overall shape is the easy part, says Robert Benjamin, a physicist at the University of Wisconsin and a member of the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) project. “In the Milky Way, we can see the individual trees but it's hard to make out the forest.” GLIMPSE, a Spitzer project, has mapped more than 100 million stars throughout a 130-degree swath of the Milky Way. An extension of the…

age: 4.6 billion years mass: 13,000,000,000,000,000,000,000,000 pounds polar circumference: 24,818 miles equatorial circumference: 24,901 miles The first life—single-celled organisms—probably arose on Earth 3.8 billion years ago. Fossils of primitive animals, such as jellyfish-like creatures, date back only as far as 600 million years. 1 million billion The lower estimate for the number of ants on Earth Current upper estimates predict that there may be more than 100 million types of multicellular species on Earth. 12,600°f The highest temperature that may exist in Earth's interior—hotter than the surface of the sun It takes 1 hour for the Earth to receive more solar energy than the amount of energy consumed from fossil fuels globally in a year. 40,226 feet The depth of the deepest hole ever bored on Earth, on Russia's Kola…

Geography: Canada Botany: Fern Sports: Bobsled Zoology: Penguin Beverages: Tea History: 1962 1. 3 × 4 − 9 + 7/5 = 2 2. See diagram. The marked tiles are colored dark blue. 3. Seven bees. See the diagram for one of a few possible solutions. 4. 10 paths to E. The diagram shows the number of paths to each circle. Each number is the sum of the numbers in the circles that lead to it. 6 + 4 = 10, so there are 10 paths to E. 5. 12. The numbers in the second column can be obtained from the numbers in the first column by rearranging them and changing one “b” to a “c.” It follows that “c” must be 4 less than “b.” Similarly, the numbers in the…

Oxygen was first discovered in around 1772 by the Swedish chemist Carl Wilhelm Scheele, although Joseph Priestly, an English chemist, independently discovered it in 1774 and published his findings before Scheele. Soon after, the French chemist Antoine-Laurent Lavoisier identified oxygen's role in respiration and combustion. The Chinese concocted the recipe for early gunpowder in the 9th century and used it in the first crude cannons. By the late 14th century, Europeans were using powerful modern cannons, initially called bombards, as weapons.…

Genes are the instructions to make proteins, which are responsible for almost all of the processes that keep organisms alive. In 1973, biochemists Stanley Cohen of Stanford University and Herbert Boyer of the University of California at San Francisco first transferred genes for antibiotic resistance into E. coli bacteria. These early pioneers of genetic engineering may not have imagined how influential their work would become. These days, genetic engineering techniques are used, for example, to insert genes from other organisms into bacteria, which then churn out proteins that produce hepatitis-B vaccine and insulin for diabetics. Botanists genetically modify crops to boost hardiness and nutritional value. Yet geneticists do more than bestow organisms with new characteristics. They also manipulate DNA to study the role of individual genes. Scientists add, delete, or…

The lush jungles of the Brazilian Amazon were once considered uninhabitable. But now researchers have found the remains of dozens of communities in the rainforest, along with traces of a man-made miracle soil that may have provided food for tens of thousands of inhabitants In a letter to his wife sent on May 29, 1925, Percy Fawcett, an English adventurer, reported that he was about to depart on an expedition into previously unexplored areas of the Amazon jungle in central Brazil. His goal was to find a hidden city that he referred to as “Z.” It was I Fawcett's last contact with the outside world—he disappeared without a trace—and whether he succumbed to disease, human violence or animal attack is still unknown. Now, more than 80 years later, anthropologist Michael…

age: 4.6 billion years mass: 13,000,000,000,000,000,000,000,000 pounds polar circumference: 24,818 miles equatorial circumference: 24,901 miles The first life—single-celled organisms—probably arose on Earth 3.8 billion years ago. Fossils of primitive animals, such as jellyfish-like creatures, date back only as far as 600 million years. 1 million billion The lower estimate for the number of ants on Earth Current upper estimates predict that there may be more than 100 million types of multicellular species on Earth. 12,600°f The highest temperature that may exist in Earth's interior—hotter than the surface of the sun It takes 1 hour for the Earth to receive more solar energy than the amount of energy consumed from fossil fuels globally in a year. 40,226 feet The depth of the deepest hole ever bored on Earth, on Russia's Kola…