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Solar’s failure to spread across the United States, according to renewable energy advocates, lies not with flaws in technology or lack of sun, but in the scarcity of financing. On Wednesday, the nation’s largest provider of rooftop solar systems, SolarCity, tackled that problem head-on, announcing it will now act as direct lender to customers and offer low-interest loans to finance solar energy installations. The company’s new financing option, MyPower, lets homeowners own the solar panels without the upfront costs that can top $30,000 for a mid-sized home system....

Despite having been subdued in many parts of the world by the 1970s, malaria—and the mosquitoes that spread it—has come back in force, now killing at least a million people worldwide each year. An efficient illness, the parasite has become largely resistant to the popular drug chloroquine, and many mosquitoes have similarly developed resistance to the pesticide DDT. Most of its casualties are children, and of the hundreds of millions who survive the disease, many are left disabled and vulnerable to reinfection from the parasite’s liver-dwelling cells....

The peak of the Atlantic hurricane season has arrived and is living up to its name: Two storms, Laura and Marco, developed within the relatively small confines of the Gulf of Mexico and Caribbean Sea area late last week. Their formation has already put the season halfway through the alphabetical list of available storm names—a clear sign that 2020 is meeting forecasts for a very active season amid a disastrous pandemic and major economic uncertainty....

Key concepts Chemistry Water Oil Surfactants Foams Introduction We lather our scalps with shampoo all the time. But what exactly makes a good shampoo? You might be surprised to hear every new shampoo has to pass lots of scientific tests before it is considered good enough to be sold. Many different shampoo recipes are compared to decide which is best for the consumer. One of these tests assesses the foaming behavior of the shampoo....

A new, ultraslim silicon film may be just the thing for filtering molecules of different sizes, such as the waste products removed during kidney dialysis. Researchers have grown porous, 50-atom-thick layers of silicon that block the passage of some protein molecules while letting others of nearly the same size pass through. “This is a tremendous leap forward in membrane technology,” says materials researcher Christopher Striemer of the University of Rochester, part of a group that created the filters and has formed a start-up company to commercialize them....

Researchers think they have come up with a way to tell fossils of male dinosaurs from those of females—at least for some small feathered species. The key differences between the sexes lie in bones near the base of the tail, the scientists reported on March 31 in Scientific Reports. The team examined a pair of fossils unearthed in Mongolia in the mid-1990s and first described in 2001. Because the turkey-sized oviraptorosaurs (“egg-thief lizards”) were found mere centimetres from each other in a 75-million-year-old rock layer, some scientists have nicknamed the pair ‘Romeo and Juliet’....

The koala is a cutie, but does it steal too much of the limelight? A new study adds quantitative detail to an ongoing debate over whether such “conservation mascots” receive publicity and funding to the detriment of animals typically deemed less attractive. Researchers at Murdoch University and Curtain University, both in Western Australia, combed through 14,248 journal papers, books and conference proceedings about 331 Down Under mammals and found an overwhelming bias against investigations of “ugly” species....

The story of how the universe came to be is constantly evolving. Indeed, a trove of fresh data rolling in from the Gaia spacecraft is refining our view of the early years of our galaxy. A violent collision with a second galaxy about eight to 11 billion years ago left a cohort of stars strewn askew from the plane of the Milky Way—the fingerprint of early galactic growing pains (see “Hidden History of the Milky Way Revealed by Extensive Star Maps”)....

The conclusion of the Paris Agreement in 2015, in which almost every nation committed to reduce their carbon emissions, was supposed to be a turning point in the fight against climate change. But many countries have already fallen behind their goals, and the U.S. has now announced it will withdraw from the agreement. Meanwhile emissions worldwide continue to rise. The only way to make up ground is to aggressively pursue an approach that takes advantage of every possible strategy to reduce emissions....

Scientists do not yet fully understand how the H7N9 avian influenza virus is spreading in China, or why the pattern of sporadic human cases looks like it does. But mapping the risks of known factors in the past geographical spread of avian flu viruses and human infections might provide some clues. The first known cases of human infection with H7N9 were reported in China on 31 March, with two cases in Shanghai on the eastern seaboard and one in the neighboring province of Anhui....

Birdsong—or, more technically, vocalization— is one way that die-hard bird-watchers identify different kinds of birds in the field, along with the more traditional visual markers. Yet how do you take written notes on the sounds that birds make? You could use conventional musical notation, but many bird-watchers aren’t musicians. Field guides often resort to vague phrases such as “far-carrying melancholic song” or the mysterious “tee-do-do-eet.” Also, how can birders identify strains of birdsong they may hear in the field?...

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The Seven Cities of Cibola are the mythical lands of gold that the Spanish of the 16th century believed existed somewhere in the southwest of North America, comparable to the better-known mythical city of El Dorado. No sites matching the descriptions of the European explorers who first reported them were found but these launched an expedition which destroyed many others....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The knights of medieval Europe were meant to be the finest fighting men of their age, even more important, they were expected to be pure in thought and deed, as exemplified in the chivalrous code which they (usually) followed. Here are the stories of 12 such knights. The legendary figures are perhaps based on historical knights and the historical knights have all become legendary; such is the indistinct line of truth between fact and fiction and humanity’s need to create larger-than-life figures of a by-gone age when valour and chivalry reached their apex....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Pausanius (l. 110-180 CE) was a geographer and historian who traveled extensively, taking notes on points of interest, then wrote on them in guide books which could be used by tourists visiting the sites described. His works have long been recognized for their accuracy and have served as guides for archaeologists and historians in the modern era as in antiquity....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Following the conquest of North Africa by Muslim Arabs in the 7th century CE, Islam spread throughout West Africa via merchants, traders, scholars, and missionaries, that is largely through peaceful means whereby African rulers either tolerated the religion or converted to it themselves. In this way, Islam spread across and around the Sahara Desert....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Society in the Kingdom of France in the period of the Ancien Regime was broken up into three separate estates, or social classes: the clergy, the nobility, and the commoners. These classes and their accompanying power dynamics, originating from the feudal tripartite social orders of the Middle Ages, was the fabric in which the kingdom was woven....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Women in the New Testament are presented for the most part along the contours of both Jewish and Greco-Roman concepts of the social construction of gender roles. Women’s value to society was in their role in procreation. There are some exceptions, however, in the gospels and particularly in the letters of Paul....

Engineers often load a structure with weight until it collapses or shake it until it flies apart. Like engineers, many scientists also have a secret love for destructive testing—the more catastrophic the failure, the better. Human vision researchers avoid irreversible failures (and lawsuits) but find reversible failures fascinating and instructive—and sometimes even important, as with the devastating spatial disorientations and visual blackouts that military pilots can experience. At the U.S. Air Force Research Laboratory, the two of us explore the most catastrophic visual failures we can arrange....

San Rafael, Calif., 2002—A NIST Web site boasts that an atomic chronometer it has constructed “would neither gain nor lose one second in about 3.7 billion years.” Atomic horologists often speak as if their timepieces could run continuously for thousands of centuries. Balderdash—a typical cesium clock lasts no more than 20 years. A decent wristwatch runs longer. But at facilities in California and Seattle, a small group of futurists and engineers have begun building a mechanical clock meant to tick through 1,000 decades....

For all the images of ski resorts and snow-capped peaks, Colorado is experiencing shorter winters and hotter summers that are increasingly putting people at risk for heat-related illnesses. Yet until this year, the National Weather Service hadn’t issued a heat advisory for the Denver metropolitan area in 13 years. That’s because the heat index commonly used by the weather service to gauge the health risks of hot weather relies on temperature and humidity....