Science

Attitudes about marijuana seem to be changing and diversifying in Latin America. Throughout the 20th century its consumption was associated with criminal behavior. But over the last decade the drug’s image has improved in some countries. A new survey reveals that in some Latin countries more than 40 percent of the population is in favor of legalizing marijuana, although in other countries favor remains low. “Until now, the scientific literature showed that Latin America had a consistent position on decriminalization,” says lead author Andrés Mendiburo Seguel, a sociologist at the University of Santiago, Chile. “Our work points out that there are differences of opinion that could influence future public policies adopted in the region.” The survey was conducted by Mendiburo Seguel and researchers at Andrés Bello National University of Chile and the University of London, and was published in the International Journal of Drug Policy. The researchers interviewed 8,952 adults in large cities in nine …

Tiny and blue: STED image of UCNPs A new way of beating the diffraction limit in optical microscopy has been unveiled by physicists in Australia and China. The technique makes use of nanoparticles to improve the efficiency of stimulated emission depletion (STED) microscopy, allowing it to be used with lower levels of illumination than previously possible. STED microscopy was developed by the Germany-based physicist Stefan Hell, who won one third of the 2014 Nobel Prize for Chemistry for his work on the technique. The technique allows features much smaller than the wavelength of light to be observed with a microscope – something that is impossible with conventional microscopes. Doughnut’s hole STED involves tagging regions of interest in a sample with fluorescent molecules and using a beam of light to cause the molecules to emit light. A second “depletion” beam of light is focused to a doughnut shape in the sample and suppresses the fluorescence everywhere …

Seawater supplies: carbon–polymer electrodes can extract the sea’s uranium Uranium has been extracted from seawater using electrochemical methods. A team at Stanford University in California has removed the radioactive material from seawater by using a polymer–carbon electrode and applying a pulsed electric field. Uranium is a key component of nuclear fuel. On land, there are about 7.6 million tonnes of identified uranium deposits around the world. This ore is mined, processed and used for nuclear energy. In contrast, there is 4.5 billion tonnes of the heavy metal in seawater as a result of the natural weathering of undersea deposits. If uranium could be extracted from seawater, it could be used to fuel nuclear power stations for hundreds of years. As well as taking advantage of an untapped energy resource, seawater extraction would also avoid the negative environmental impacts of mining processes. Tiny concentrations Scientists are therefore working on methods to remove and recover uranium from …

Dinosaurs, Star Wars, train schedules, Disney princesses, maps, LEGO—subjects such as these can become all-consuming passions for children on the autism spectrum. What therapists and educators often call “circumscribed” or “restricted” interests (or, more generously, “special” interests) make up a characteristic symptom of autism spectrum disorder (ASD). The current edition of psychiatry’s Diagnostic and Statistical Manual of Mental Disorders describes them as “highly restricted, fixated interests that are abnormal in intensity or focus.” Roughly 90 percent of high-functioning kids with ASD display at least one such interest during their elementary school years, according to a 2007 survey conducted at the Yale University Child Study Center, one of the few studies to have examined the topic. For a family with an affected child, this kind of narrow preoccupation can be tedious and exhausting. Imagine a kid who will talk about nothing but the exits on the New Jersey Turnpike or the Captain Underpants book series. (Both …

Seven worlds: artist’s impression of TRAPPIST-1 The largest known system of Earth-like exoplanets has been found orbiting a dwarf star in the Milky Way. At least three of the seven rocky exoplanets could have oceans of water, making it possible that the system could harbour life. The discovery lends weight to the growing belief among some astronomers that our galaxy could be teeming with Earth-like worlds. The first exoplanet – a planet orbiting a star other than the Sun – was discovered more than 30 years ago, and since then, astronomers have identified thousands of such objects. Most are Jupiter-like gas giants because huge exoplanets are much easier to detect than smaller Earth-like worlds. However, improved techniques and new telescopes have led to the discovery of Earth-like exoplanets with the potential to harbour life. In 2010, an international team of astronomers began using the TRAPPIST telescope in Chile to search for Earth-like exoplanets orbiting small …

In 1896 archaeologists excavating Pueblo Bonito, a 650-room, multistory brick edifice in northwestern New Mexico’s Chaco Canyon, found the remains of 14 people in a burial crypt. Necklaces, bracelets and other jewelry made up of thousands of turquoise and shell beads accompanied the bones. The artifacts signaled that these individuals were elite members of the ancient Chaco society, one of the most important civilizations in the American Southwest. The excavations at Pueblo Bonito revealed the splendors of Chaco culture, which flourished between about A.D. 800 and 1250. The ancient Chacoans constructed at least a dozen great houses like Pueblo Bonito in Chaco Canyon during its heyday, and dozens of other Chacoan settlements thrived in what is today the Four Corners region where the borders of New Mexico, Colorado, Arizona and Utah meet. Soon after the excavations ended, archaeologists whisked these human remains off to the American Museum of Natural History (AMNH) in New York City, …

Ten years ago Dennis Degray’s life changed forever when he slipped and fell while taking out the trash in the rain. He landed on his chin, causing a severe spinal cord injury that left him paralyzed below the neck. Now he’s the star participant in an investigative trial of a system that aims to help people with paralysis type words using only their thoughts. The promise of brain–computer interfaces (BCIs) for restoring function to people with disabilities has driven researchers for decades, yet few devices are ready for widespread practical use. Several obstacles exist, depending on the application. For typing, however, one important barrier has been reaching speeds sufficient to justify adopting the technology, which usually involves surgery. A study published Tuesday in eLifereports the results of a system that enabled three participants—Degray and two people with amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease, a neurodegenerative disease that causes progressive paralysis)—to type at the …

Top of the class: parents can influence their child’s STEM performance Teenagers with parents who conveyed the importance of science, technology, engineering and mathematics (STEM) had higher scores in mathematics and science-college preparatory examinations, a long-term US study has found. Talking to teenagers about the benefits of science boosted their exam results by as much as 12%, which in turn increased the number pursuing STEM-based careers. The research was part of a longitudinal study that recruited families in the state of Wisconsin in 1990 and 1991 when mothers were pregnant. The STEM part of the analysis, led by psychologist Judith Harackiewicz from the University of Wisconsin–Madison, looked at 181 families from that cohort with students attending 108 different high schools. Utility and relevance These families were randomly assigned to either an “intervention” group or a control group. Parents in the intervention group were sent information about the utility and relevance of mathematics and science for …

For much of her life Anne Dalton battled depression. She seldom spoke with people. She stayed home a lot. The days dragged on with a sense of “why bother?” for the 61-year-old from New Jersey who used to work at a Wall Street investment firm. After trying more than a dozen combinations of antidepressant drugs to no avail, things got so bad two years ago that Dalton went in for electroconvulsive therapy—in which “basically they shock your brain,” as she puts it. Like Dalton, most of the estimated 16 million U.S. adults who have reported a major depressive episode in the past year find little relief even after several months on antidepressants—a problem that some researchers say may stem from the way mental illness is diagnosed. Objective lab tests can physically confirm heart disease or cancer, but psychiatric conditions are classified somewhat vaguely as clusters of reported symptoms. Doctors consider people clinically depressed if they …

The world changed forever some three million years ago, scientists have thought. At that time, for the first time, a ribbon of dry land connected North and South America, as the Isthmus of Panama shook free of the water around it. The new land bridge allowed plants and animals free travel between the two continents, colonizing new worlds. It also changed ocean currents and ushered in an ice age. Now this textbook date is being challenged. The south-north connection happened around 15 million years ago and perhaps even earlier, not a paltry three million, argues Camilo Montes, a geologist at the University of the Andes in Bogotá. In a series of studies over the last four years Montes and a small but vocal group of evolutionary biologists and geologists have proposed this older date based largely on the age of rocks and fossils unearthed during the recent widening of the Panama Canal. “The work supporting …

1 2 3 13