Key Concepts Biology Chemistry Chemical reactions Enzymes Food Introduction Have you ever wondered why apple slices turn brown once you cut them, or why a yellow banana gets dark spots over time? Both of these phenomena have the same cause: enzymatic browning triggered by an enzyme called polyphenol oxidase (PPO). In this activity you will find out how this enzyme works by turning a banana from yellow to brown in just a matter of seconds....
ATLANTA—Zika infection during pregnancy can lead to birth defects except, of course, when it does not. Now scientists are wondering why the virus catastrophically affects some fetuses but not others. In Colombia, where the number of known Zika infections is second only to Brazil, there have been relatively few cases of related birth defects: 57 compared with more than 2,000 in Brazil, according to the World Health Organization. The U.S. has the third-highest number of Zika-related birth defects, with 31 combined cases and lost pregnancies due to miscarriage....
With 80 percent of California in a state of extreme drought, you wouldn’t think dust would be the answer to the state’s water woes. New research presented in San Francisco yesterday suggests, however, that dusty air blown across the Pacific Ocean from Asia and Africa could be influencing precipitation in the region. In a presentation at a national meeting of the American Chemical Society yesterday, Kim Prather from the University of California, San Diego, described research she is leading into the dust swept westward by the jet stream....
Like infectious diseases, ideas in the academic world are contagious. But why some travel far and wide while equally good ones remain in relative obscurity has been a mystery. Now a team of computer scientists has used an epidemiological model to simulate how ideas move from one academic institution to another. The model showed that ideas originating at prestigious institutions caused bigger “epidemics” than equally good ideas from less prominent places, explains Allison Morgan, a computer scientist at the University of Colorado Boulder and lead author of the new study....
Sea otters eat sea urchins and sea urchins eat kelp. When sea otters are present, the coastal kelp forests maintain a healthy balance. But when the fur trade wiped out the otters in the Aleutian Islands in the 1990s, sea urchins grew wildly, devouring kelp, and the kelp forest collapsed, along with everything that depended on it. Fish populations declined. Bald eagles, which feed on fish, altered their food habits. Dwindled kelp supplies sucked up less carbon dioxide, and atmospheric carbon dioxide increased....
A new network of dedicated antennas in Africa will lend insight into the havoc that storms of charged particles from the sun wreak on satellite and radio communications. Zambia set up its first such sensor in March—one of eight multifrequency receivers being deployed around the continent, in addition to four already operating in South Africa. Kenya and Nigeria will install their receivers by the end of the year. Feeding into an upgraded space weather center scheduled to open in South Africa in 2022, the network will provide real-time data on how solar storms distort the ionosphere, the charged outer layer of Earth’s atmosphere....
Evidence for a never-before-seen particle containing four types of quark has shown up in data from the Tevatron collider at the Fermi National Accelerator Laboratory (Fermilab) in Illinois. The new particle, a class of “tetraquark,” is made of a bottom quark, a strange quark, an up quark and a down quark. The discovery could help elucidate the complex rules that govern quarks—the tiny fundamental particles that make up the protons and neutrons inside all the atoms in the universe....
Special Report: Pollution, Poverty, People of Color Communities across the US face environmental injustices Part 2 of Pollution, Poverty and People of Color RICHMOND, Calif.—“Sa Bai Dee,” begins the small, white-haired man in the lime-green T-shirt, speaking in his native dialect, Khmu. “Good evening, Madame Mayor and members of the city council,” translates the younger man in a matching green shirt, “I am Lipo Chanasack. I live here in Richmond.” Through his translator, Chanasack urges the seven members of the Richmond City Council to reduce the outsized environmental burden on the low-income, largely non-white neighborhoods beneath the city’s industrial smokestacks....
The amount of food we waste is enough to make you sick … many times over. Thelatest installment [pdf] in the World Bank’s “Food Price Watch” series has just been released. If you’re a consumer — and when it comes to food, aren’t we all — there’s some good news: food prices between October 2013 and January 2014 have continued the modest decline that began last summer. But the report documents some disturbing data as well: the huge amounts of food lost and wasted each year1 —especially by us North Americans....
Some tech flops are famous and well documented: Microsoft Bob. The Segway scooter. The Iridium satellite cellphone. (You think you’ve got indoor-reception problems with your current cellphone? How’d you like a phone with $8 a minute airtime charges that doesn’t work at all without a line of sight to the sky?) Other dogs came and went so fast, they’re now completely forgotten, lost among the dust bunnies of consumer-tech history. For those of us in the tech-review business, however, these flopperoos live on as painful memories—and cautionary tales....
The ocean is warming much faster than previously thought, new research has found, suggesting that global climate goals may be even harder to reach. The new study published yesterday in the journal Nature concluded that the global oceans may be absorbing up to 60 percent more heat since the 1990s than older estimates had found. Previous estimates from the U.N. Intergovernmental Panel on Climate Change found that the oceans were taking up around 8 zetajoules of energy each year....
Ever since his death in 1955, scientists have asked what featurs of Albert Einstein’s brain contributed to his extraordinary insights into physical laws. Research on the anatomy of Einstein’s genius, which dates back decades, faltered because many of the postmortem images and slides of tissue were scattered and became unavailable to researchers. A study published online last November in Brain, based on the most comprehensive collection of postmortem images compiled to date, shows that Einstein’s cerebral cortex, responsible for higher-level mental processes, differs much more dramatically than previously thought from that of a person of average intelligence....
WASHINGTON (Reuters) - U.S. greenhouse gas emissions fell nearly 10 percent from 2005 to 2012, more than halfway toward the U.S.’s 2020 target pledged at United Nations climate talks, according to the latest national emissions inventory. The report showed that emissions dropped 3.4 percent from 2012 to 2011, mostly due to a decrease in energy consumption and fuel switching from coal to natural gas. The Environmental Protection Agency on Tuesday published the U....
The U.S. military plans to try to blast a malfunctioning satellite out of the sky by the end of the month to prevent the bus-size hunk of metal from leaking highly hazardous fuel into the atmosphere as it falls to Earth. The U.S. Department of Defense says the Navy will use surface-to-air missiles to knock it out sometime after February 20, when the space shuttle Atlantis is scheduled to return from its mission to the International Space Station....
Laurel recently requested an episode on seitan: What the heck is it, how does it stack up nutritionally, and how do you eat it? Seitan is not a new thing. The word (pronounced say-tan) is Japanese and was coined just 50 years ago by one of the proponents of the macrobiotic diet. But the food it refers to has been a staple in Asian cultures for at least 15 centuries. I remember seeing it (but not buying it) at the Food Coop I belonged to as an undergraduate at Boston University....
Kevin Langdon is writing several books and designing an inside-out clock. Karyn Huntting Peters is organizing a global problem-solving network. Alfred Simpson juggles multiple Web-programming projects in his free time. These three people might not have much in common—except for their unusually high IQs. All three belong to exclusive high-IQ societies. Mensa International, whose members’ test scores must land above the 98th percentile (or one in 50), may be the most popular, but it is just one option for the discerning test taker....
It is an underappreciated irony that talking about complex systems is difficult. “There is no clear definition of complex systems,” says Kunihiko Kaneko, a physicist at the University of Tokyo. “But roughly speaking, there are many interacting elements, and they often show chaotic or dynamic behavior.” This year, for the first time, the Nobel Prize in Physics was explicitly awarded for research in complex systems—including climate change. Half of the prize went to Syukuro “Suki” Manabe of Princeton University and Klaus Hasselmann of the Max Planck Institute for Meteorology in Hamburg, Germany, “for the physical modelling of Earth’s climate, quantifying variability and reliably predicting global warming....
One afternoon last fall a Reddit user with the handle “FranktheShank1” was enjoying a new video game on his PlayStation 4. The game, Super Meat Boy, was considered a classic among gamers since its debut in 2010, and its release for Sony’s newest console had been highly anticipated. After playing Super Meat Boy for an hour FranktheShank1 reported that it seemed to be delivering the desired effect. “I’m already throwing tantrums and curling my toes,” he wrote on Reddit....
Read Part 1, Part 2 and Part 3 of this series. Only movie stars and select consumers have been able to get their hands on hydrogen fuel cell vehicles in the United States over the past few years, but now these zero-emissions cars are poised to bust onto the scene in a big way around 2015 to 2017. A limited number of fuel cell electric vehicles (FCEVs) are available for lease today, and nearly all of them in California, where refueling stations are slowly cropping up....
Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The English historian Edward Gibbon (1737-1794) wrote and published his seminal work History of the Decline and Fall of the Roman Empire between 1776 and 1788. The dominant theme of Gibbon’s six-volume work is that the fall of the Roman Empire was due to the rise of Christianity with its negative effects on the people and politics of Rome....
