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BPA and other estrogenic compounds hamper development of the stem cells responsible for producing sperm in mice, which suggests such exposure could contribute to declining sperm counts in men, according to a new study. The study, published online today in PLoS Genetics, is the first to suggest that low, brief exposures to bisphenol-A, or other estrogens such as those used in birth control but found as water contaminants, early in life can alter the stem cells responsible for producing sperm later in life....

Key concepts Physics Sound Vibrations Material science Introduction Have you ever thought about the sheer number of words that exist in the English language to describe sounds? A noise can be a thud, a clang, a bang, a pop, a crash, a splash, a clatter, a buzz, a tinkle and many more! You can probably think of an example for each of these—but if you heard the sound, could you say what produced it?...

PARIS—On April 7, 2013, Kenya’s Peter Some won the 37th Paris Marathon with a time of 2:05:38. A surprise winner, Some missed the event record by only 27 seconds, thus depriving him of a place in running history. He need not have worried; unknown to him and thousands of fellow marathoners, they were all nonetheless part of a historic event. As they ran across the Avenue des Champs Élysées and thumped their feet on 176 special tiles laid on a 25-meter stretch, the athletes generated electricity....

C’mon, docs. Give it to us straight. That’s the message one researcher has for the planet’s physicians, the climate scientists who are diagnosing whether a new international agreement can keep us from busting the boundary of dangerous global warming. Oliver Geden, a senior research fellow at the German Institute for International and Security Affairs in Berlin, makes the case that the accord expected to be signed in Paris in December won’t even put the world within reach of keeping global temperatures from rising more than 2 degrees Celsius above preindustrial levels....

Treatment: Stimuvax Maker: Biomira/Merck KGaA Stage: Phase III expected to begin December 2006. Why It Matters Lung cancer is the leading cause of cancer-related death in the United States for both men and women. It is more lethal than the next three most common cancers combined (colon, breast and prostate) and will kill 160,000 people in the United States in this year alone. How It Works Stimuvax is designed to vaccinate the body against Nonsmall cell lung cancer (NSCLC), which accounts for about 80 percent of all cases....

Mexico’s Senate unanimously approved landmark climate change legislation yesterday that sets the country on a pioneering path to drastically reduce its domestic greenhouse gas emissions. The measure calls for Mexico to cut carbon 30 percent below business-as-usual growth by 2030 and 50 percent by midcentury. It now goes to President Felipe Calderón, who has championed action to control climate change and is expected to sign it. Once the legislation is finalized, Mexico will be only the second country after the United Kingdom to have domestic global warming legislation in place, activists said....

NASA’s latest Earth-observation satellite blasted off today (Feb. 11), continuing a storied four-decade effort to track environmental change and resource use across the planet. The Landsat Data Continuity Mission launched today at 1:02 p.m. EST (1802 GMT/10:02 a.m. PST) from Vandenberg Air Force Base in California, riding a United Launch Alliance Atlas 5 rocket into space without any apparent hitches. The $855 million LDCM spacecraft is the eighth satellite in the history of the Landsat program, a joint NASA/United States Geological Survey (USGS) project that has been monitoring forest loss, glacial retreat, urban sprawl and other phenomena continuously since Landsat 1 lifted off in July 1972....

Mosquitoes are not just a nuisance—they spread devastating diseases, including malaria and Zika virus, which have triggered global health crises. In 2015 alone, malaria struck about 212 million people and killed an estimated 429,000, most of them in sub-Saharan Africa. Wealthy nations such as the U.S. have effective mosquito-control measures in place, but many developing countries cannot afford them. “Right now we’re limited in the number of ways we have to control mosquitoes,” says Edmund Norris, an entomologist at Iowa State University....

Researchers have discovered that the same nerve cells involved in forming memories also are involved in replaying them. The finding, published today in the online edition of Science, provides new insight into how complex memories are laid down in a single neuron (nerve cell) and how neural firing, or communication, patterns created during memory formation are maintained during recall. Scientists at the University of California, Los Angeles, (U.C.L.A.) showed 13 volunteers—epilepsy patients with therapeutic electrodes implanted in their brains—several five- to 10-second clips from videos such as The Simpsons....

A long, long time ago I dropped an American history course after the professor answered a student’s question with, “In some cases, people were as much a part of the problem as anyone else.” At the time, I doubted this guy had much to teach me. But recent events have made me reconsider his pedagogical prowess. I now believe people may indeed be as much a part of the problem as anyone else....

By Will Dunham WASHINGTON, April 28 (Reuters) - Research in a German laboratory involving five lizards called Australian bearded dragons indicates that these reptiles may dream and could prompt a fundamental reassessment of the evolution of sleep. Scientists said on Thursday they have documented for the first time that reptiles, like people, experience rapid eye movement, or REM, sleep and another sleep stage called slow-wave sleep. Until now, only mammals and birds were known to experience these....

Scientists have teamed up two materials to soak up more sunlight in a new solar cell. The dynamic duo in this case was silicon, the workhorse of conventional photovoltaics, and a mineral called perovskite. First discovered in the Ural Mountains and named for Russian mineralogist Lev Perovski, the mineral is a crystal made of calcium titanium oxide that has useful photovoltaic properties. In a conventional solar cell, only part of the solar spectrum is put to use, with the rest reflected or wasted as heat....

In the months after Nissan’s announcement last year that it would soon introduce the Leaf, the world’s first mass-market electric vehicle, the company embarked on a 24-city “zero-emission tour” to show off the technology. The Leaf’s electric motor draws its energy from a battery pack that plugs into an outlet in your garage. It has no engine, no gas tank and no tailpipe. And during the time the car is on the road, it is truly a zero-emission machine....

In the summer and fall of last year, the Greek financial crisis tore at the seams of the global economy. Having run up a debt that it would never be able to repay, the country faced a number of potential outcomes, all unpleasant. Efforts to slash spending spurred riots in the streets of Athens, while threats of default rattled global financial markets. Many economists argued that Greece should leave the euro zone and devalue its currency, a move that would in theory help the economy grow....

Stepping onto an inch-and-a-half thick piece of lake ice—much less doing laps on it—is a no-go for most people. But for experienced Swedish skaters Henrik Trygg and Mårten Ajne, few things top skating on thin ice. In December, still photographer Trygg filmed Ajne skating on 1.8 inches of fresh ice on a lake outside Stockholm. The resulting mini-documentary— filled with the eerie, laser-like sounds of bending ice—went viral in February. One shot shows the ice, commonly called “black ice,” visibly bending under the skater’s weight....

NASA scheduled the first all-female space walk for the end of last month. But a mere four days before the historic event was meant to happen, they scrapped the plan and subbed in a male astronaut, claiming it was because they did not have enough space suits in the proper size to fit all the women astronauts. Unfortunately, women all too often must make do with equipment designed for men, an oversight that can be more than a PR embarrassment....

By Steve Gorman Aug 9 (Reuters) - Some 3 million gallons of toxic wastewater, triple previous estimates, have poured from a defunct Colorado gold mine into local streams since a team of Environmental Protection Agency workers accidentally triggered the spill last week, EPA officials said on Sunday. The discharge, containing high concentrations of heavy metals such as arsenic, mercury and lead, was continuing to flow at the rate of 500 gallons per minute on Sunday, four days after the spill began at the Gold King Mine, the EPA said....

Around the time you read this, the popular Introduction to Arti­ficial Intel­ligence course at Stan­ford University, taught by Sebastian Thrun, director of the AI lab there, and by Peter Norvig, director of research for Google, will be under way. As usual, a couple of hundred Stanford students will be sitting in the room. This year classmates sitting at computers around the world will join them. The pupils who attend virtually won’t pay tuition (or get Stanford credit), but they will all watch the same lectures, read the same textbook, get the same homework and take the same tests....

Astronomers have seen a distant galaxy that blasts away material with two trillion times the energy the sun emits—the biggest such eruption ever seen. That ejection of matter could answer an important question about the universe: why are the black holes in the centers of galaxies so light? Computer models of the early universe usually produce a virtual cosmos that looks like ours except for one thing. The ratio of the mass of black holes in galaxy centers to the rest of the matter in galaxies is larger in the simulations than in the real universe....

Growing cellulosic feedstocks on federally subsidized conservation land could balance the biofuels emissions equation to be completely carbon-neutral, a study suggests. For conventional bioenergy feedstocks like corn and soy, using a no-till method to remove weeds can shrink the number of years needing to balance the carbon budget by one-third. The research is centered on the Agriculture Department’s Conservation Reserve Program, a voluntary program that rewards farmers who save a portion of their land for conservation of watersheds and wildlife....