| It makes sense that the male and female members of a species should look or smell or sound a little different enough that they can tell each other apart during mating season. But extreme differences are hard to square with the principle of survival of the fittest. | | How do you get inside a whale's head? With a CT-scanner made for rocket bodies, that's how.Researchers from San Diego State University stuck an entire juvenile minke whale inside a computed tomography (CT) scanning machine to virtually slice and dice its anatomy with X-rays. Their goal was to get a look at the structures that allow whales to hear underwater and better understand a sense that's vital for these underwater mammals. | | There is a borderland between waking life and the uncharted wilderness of sleep that we all traverse each night, but we rarely stop to marvel at the strangeness of this liminal world. If we do, we find that it is full of hallucinations both wonderful and terrifying, a mental goulash of reality and fantasy. | | Cotton thread is made of many tiny fibers, each just 2-3 cm long, yet when spun together the fibers are capable of transmitting tension over indefinitely long distances. From a physics perspective, how threads and yarns transmit tensionmaking them strong enough to keep clothes from falling apartis a long-standing puzzle that is not completely understood. | | The internal structure of the thorium-229m nuclear state has been studied in detail for the first time by physicists in Germany. Thorium-229m is a metastable (or isomer) excited state of thorium-229 that decays via the emission of an ultraviolet (UV) photon. This photon has much lower energy than most nuclear emissions and could form the basis of a nuclear clock that would be much more precise than existing atomic clocks. | | During the early weeks of his 167-day stint aboard the International Space Station in 2014, astronaut Barry Butch Wilmore noticed that a torque wrench was missing. It's not uncommon for things to disappear in space, he tells me over the phone from the Johnson Space Center in Houston. | | The genome of the flu virus has been fully sequenced in its native RNA form for the first time. Previously, all influenza genomes as well as those of other viruses that store their genetic material as RNA had been determined by copying the molecule into DNA. The native flu genome was generated using nanopore' sequencing technology, which reads RNA strands as they stream through a tiny molecular channel. | JAMA The definition of normal values for common laboratory tests often governs the diagnosis, treatment, and overall management of tested individuals. Some test results may depend on demographic traits of the tested population including age, race, and sex. Ideally, laboratory test results should be interpreted in reference to a population of similar healthy individuals. In many settings, however, it is unclear exactly who these individuals are. How much population stratification and what criteria for healthy individuals are optimal? | | t's hard to keep trim when you're an old galaxy.A survey of hundreds of galaxies found a clear link between their shapes and their stars' ages, astronomers report April 23 in Nature Astronomy. Galaxies with younger stars are more squashed into flatter shapes, while galaxies with older stars are more blobby, says astronomer Jesse van de Sande of the University of Sydney. | | I'm sick and tired of Uranus jokes. It's time to get serious about Uranus, because there is some really serious science surrounding Uranus's mysteries. And wow, is Uranus mysterious.Following some of our very serious informed speculation, scientists have directly observed a molecule in the planet's deep atmosphere that confirms Uranus's stench. | | Persistence truly does pay off, even if you have to endure the perspiration that comes with it. This is true right down to the biological and evolutionary level, and is in fact how we got here, as the apex predator of the planet. Millions of years ago, digestion consumed most of the calories we ate. Our brain takes 20 times more energy than any other organ in the body. | | Mercury is the closest planet to the sun, but far from being a dull cinder of a world, it has instead turned out to be a real eye opener for geologists. Among the revelations by NASA's MESSENGER probe, which first flew past Mercury in 2008 and orbited it between 2011 and 2015, is the discovery of a hundred or so bright red spots scattered across the globe. Now they are at last being named. | | The 20th century was a period of unprecedented biological growth for our species. The average human lifespan increased from 31 years in 1900 to 66 years in 2000. Adults grew more than 8 centimeters taller. Sports records toppled on an annual basis. | | David Randall and Christopher Welser are unlikely authorities on the reproducibility crisis in science. Randall, a historian and librarian, is the director of research at the National Association of Scholars, a small higher education advocacy group. Welser teaches Latin at a Christian college in Minnesota. Neither has published anything on replication or reproducibility. | | Earth's magnetic field is one of the most mysterious features of our planet. It is also essential to life as we know it, ensuring that our atmosphere is not stripped away by solar wind and shielding life on Earth from harmful radiation. For some time, scientists have theorized that it is the result of a dynamo action in our core, where the liquid outer core revolves around the solid inner core and in the opposite direction of the Earth's rotation. | | One of the greatest cosmic puzzles in our entire Universe is why there's so much more matter than antimatter. The laws of physics, as far as we can tell, only allow you to create or destroy matter and antimatter in equal amounts. Yet when we look out at the stars, galaxies, and large-scale structure of the Universe, we find that it's all made of matter, with only trace amounts of antimatter to be found anywhere. | | Click anywhere on this site, and you'll likely run into a measurement in terms of light-years, solar masses, astronomical units, or arcminutes. These units are unique to astronomy, and all can be expressed in terms of other, more fundamental units, such as meters, grams, and degrees. | | |
沒有留言:
張貼留言