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Age is the single biggest risk factor for dementia, with the odds doubling about every five years after age 65. But many things influence those odds for a given individual. Genetic vulnerability is a contributor, as are so-called modifiable risk factors such as smoking, cardiovascular disease, social isolation, and impaired hearing and vision. Certain mental conditions, particularly depression and schizophrenia, have also been linked to dementia. But because depression can itself be a sign of cognitive decline, the causality has been a bit muddy....

When Thomas Monath, an expert on vaccines combating mosquito-borne diseases, thinks about developing an inoculation against Zika virus, he has a major concern: Guillain–Barré syndrome. The rare autoimmune disease can lead to paralysis, and recently it appears to be occurring more frequently than usual within at least eight countries and territories reporting Zika outbreaks. Mounting evidence suggests exposure to the mosquito-borne Zika is the culprit. Now that boost in Zika-linked Guillain (GBS) is stoking concerns that a vaccine designed to protect patients against Zika could inadvertently provoke more cases of the autoimmune condition....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The Aztec mosaic-handled knife currently in the British Museum, London dates to between 1400 and 1521 CE and is thought to have been used in religious ceremonies. Made from wood and flint the knife handle represents an Aztec warrior but the blade revealed no traces of blood under testing and so was probably not used to sacrifice victims, a common Aztec religious practice....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The Battle of Preston between 17 and 20 August 1648 occurred during the English Civil Wars (1642-1651) and saw Oliver Cromwell lead Parliament’s New Model Army to victory against an Anglo-Scottish army which supported King Charles I of England (r. 1625-1649). The Royalists were routed over several days in a running battle that ended the brief action known as the Second English Civil War (Feb-Aug 1648)....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. On Faith and Works (1532) by Cardinal Thomas Cajetan (l. c. 1468-1534) is a refutation of the central arguments of Martin Luther (l. 1483-1546) concerning justification before God as faith-based, having nothing to do with one’s works. Cajetan shows why Luther is wrong in this while reaffirming the Catholic stand on the importance of faith and works....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Feudalism in medieval Japan (1185-1603 CE) describes the relationship between lords and vassals where land ownership and its use was exchanged for military service and loyalty. Although present earlier to some degree, the feudal system in Japan was really established from the beginning of the Kamakura Period in the late 12th century CE when shoguns or military dictators replaced the emperor and imperial court as the country’s main source of government....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. Since the return to democracy in Chile in 1990 CE, the new governments have dealt with one of the great historical debts of the Chilean state, its relationship with the indigenous peoples. These peoples have been historically marginalized and made invisible in all spheres. However, with the revaluation of their cultural heritage, indigenous medicine and the use of elements of nature and medicinal herbs - wisdom accumulated for centuries - re-emerges....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. For the Maya, reliable food production was so important to their well-being that they closely linked the agricultural cycle to astronomy and religion. Important rituals and ceremonies were held in honour of specialised workers; from beekeepers to fishermen, and maize, the all-important Mesoamerican staple, even had its own god....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The Mongol Empire (1206-1368 CE) covered Asia from the Black Sea to the Korean peninsula and so naturally included all manner of religions within its borders, but the Mongols themselves had their own particular religious beliefs and rituals, even if there were no priesthoods, no sacred texts, and no public services, except funerals....

Forecasting influenza outbreaks before they strike could help officials take early action to reduce related deaths, which total 290,000 to 650,000 worldwide every year. In a recent study, researchers say they have accurately predicted outbreaks up to two weeks in advance—using only the content of social media conversations. The findings could theoretically be used to direct resources to areas that will need them most. A team at the Pacific Northwest National Laboratory in Washington State gathered linguistic cues from Twitter conversations about seemingly non-flu-related topics such as the weather or coffee....

By Janice Neumann (Reuters Health) - A small Australian study finds that grandmothers who take care of their grandchildren one day a week do better on cognitive tests than peers who mind grandkids more often, or not at all. Researchers say the brain benefits from this form of “grandparenting” may come not just from having social engagement, but “active” engagement in those relationships. “The key point here is they found that the socialization part was important primarily when it was associated with some kind of useful function,” said Dr....

The following essay is reprinted with permission from The Conversation, an online publication covering the latest research. Planetary science is beginning to catch up with science fiction. Since the launch of the Kepler space telescope in 2009, a deluge of planets outside of our solar system has been found, with many oddball, exotic worlds among them. One of Kepler’s most exciting discoveries was proving the existence of circumbinary planets: planets that orbit two stars, which are themselves bound together by gravity in an often-tight orbital dance....

Editor’s Note: This story is a supplement to “Advances in Monitoring Nuclear Weapon Testing” from the March 2009 issue of Scientific American. July 16, 1945: World’s first test of a nuclear device is conducted by exploding a bomb on a tower at Trinity site, Alamogordo, N.M. August 6, 1945: First atomic bomb is dropped on Hiroshima; three days later a second atomic bomb is dropped on Nagasaki. 1947: General Dwight D....

From Quanta (Find original story here). Even as he installed the landmark camera that would capture the first convincing evidence of dark energy in the 1990s, Tony Tyson, an experimental cosmologist now at the University of California, Davis, knew it could be better. The camera’s power lay in its ability to collect more data than any other. But digital image sensors and computer processors were progressing so rapidly that the amount of data they could collect and store would soon be limited only by the size of the telescopes delivering light to them, and those were growing too....

Mars will make a close approach to Earth Saturday (March 3), and interested skywatchers can follow the action live online. Every 26 months, the orbits of Earth and Mars align such that the two planets form a relatively straight line with the sun. This cosmic event is called an opposition, because the Red Planet sits on the exact opposite side of Earth from the sun. Mars will be in opposition to Earth Saturday, and it will be visible even to stargazers under the cloudiest of skies....

Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled on by Hawking Became Loved by Marcia Bartusiak Yale University Press, 2015 (($27.50)) The concept of black holes arose from general relativity, yet Albert Einstein himself assumed that they could not exist in nature: he postulated that some unknown aspect of stellar physics would keep matter from condensing to a state so extreme that even light could not escape its gravitational pull once drawn in....

By Brendan MaherThey became known as the cancer villages–tiny hamlets in Cappadocia, Turkey, that for generations have been haunted by an extremely rare lung condition. Mesothelioma, responsible for up to half of the deaths in these towns, is almost always associated with exposure to asbestos. But here, researchers found a different cause: a mineral called erionite, which is built into the very fabric of the villages. It is on the roads, in the fields and in the stone used to construct the houses....

When the United States’ landmark Clean Water Act (CWA) was signed into law in 1972, the nation’s waterways and coastlines were in crisis. Oily debris in the Cuyahoga River in Cleveland, Ohio, had notoriously caught fire several times. The southernmost of North America’s Great Lakes, Lake Erie, had been pronounced dead or dying. Fish in Californian coastal waters were so laced with the pesticide DDT that it disrupted the reproductive systems of brown pelicans, threatening them with extinction....

Warming in the Arctic is causing the release of toxic chemicals long trapped in the region’s snow, ice, ocean and soil, according to a new study. Researchers from Canada, China and Norway say their work provides the first evidence that some persistent organic pollutants (POPs) are being “remobilized” into the Arctic atmosphere. “Our results indicate that a wide range of POPs have been remobilized into the Arctic atmosphere over the past two decades as a result of climate change, confirming that Arctic warming could undermine global efforts to reduce environmental and human exposure to these toxic chemicals,” write the scientists, whose analysis was published yesterday in the journal Nature Climate Change....

One day in the future, the Pacific Ocean could be home to kilometers of seaweed farms tended by submarine drones and waiting to be turned into fuel. This is the vision of Marine BioEnergy, a start-up backed by the Advanced Research Projects Agency–Energy (ARPA-E). The U.S. government agency is funding the company, along with a handful of related projects, because it views the open ocean as a largely untapped resource for a new and potentially better source of renewable bioenergy....