Dec 30, 2016
Historically, time was based on the mean rotation of the Earth relative to celestial bodies and the second was defined in this reference frame. However, the invention of atomic clocks defined a much more precise "atomic" timescale and a second that is independent of Earth's rotation.
In 1970, international agreements established a procedure to maintain a relationship between Coordinated Universal Time (UTC) and UT1, a measure of the Earth's rotation angle in space.
The International Earth Rotation and Reference Systems Service (IERS) is the organization which monitors the difference in the two time scales and calls for leap seconds to be inserted in or removed from UTC when necessary to keep them within 0.9 seconds of each other. In order to create UTC, a secondary timescale, International Atomic Time (TAI), is first generated; it consists of UTC without leap seconds. When the system was instituted in 1972, the difference between TAI and UTC was determined to be 10 seconds. Since 1972, 26 additional leap seconds have been added at intervals varying from six months to seven years, with the most recent being inserted on June 30, 2015. After the insertion of the leap second in December, the cumulative difference between UTC and TAI will be 37 seconds.
Confusion sometimes arises over the misconception that the occasional insertion of leap seconds every few years indicates that the Earth should stop rotating within a few millennia. This is because some mistake leap seconds to be a measure of the rate at which the Earth is slowing.
The one-second increments are, however, indications of the accumulated difference in time between the two systems.
The decision as to when to add a leap second is determined by the IERS, for which the USNO serves as the Rapid Service/Prediction Center. Measurements show that the Earth, on average, runs slow compared to atomic time, at about 1.5 to 2 milliseconds per day. These data are generated by the USNO using the technique of Very Long Baseline Interferometry (VLBI). VLBI measures the rotation of the Earth by observing the apparent positions of distant objects near the edge of the observable universe. These observations show that after roughly 500 to 750 days, the difference between Earth rotation time and atomic time would be about one second.
Instead of allowing this to happen a leap second is inserted to bring the two time-scales closer together. We can easily change the time of an atomic clock, but it is not possible to alter the Earth's rotational speed to match the atomic clocks.
The U.S. Naval Observatory is charged with the responsibility for the precise determination and dissemination of time for the Department of Defense and maintains DoD's Master Clock.
The U.S. Naval Observatory, together with the National Institute ofStandards and Technology (NIST), determines time for the United States.
Modern electronic navigation and communications systems depend increasingly on the dissemination of precise time through such mechanisms as theInternet-based Network Time Protocol (NTP) and the satellite-based Global Positioning System (GPS).
Read more at Science Daily
"Spouses and friends are more likely to be around patients when they are making decisions that affect their health -- like taking a walk versus watching TV, or what to order at a restaurant. Patients are also more likely to adopt healthy behaviors -- like going to the gym -- when they can go with a friend," explains co-author David Asch, MD, MBA, a professor of Medicine at the Perelman School of Medicine at the University of Pennsylvania and director of the Penn Medicine Center for Health Care Innovation. "Though people are more heavily influenced by those around them every day than they are by doctors and nurses they interact with only occasionally, these cost-free interactions remain largely untapped when engineering social incentives for health. That's a missed opportunity."
Because of these lost opportunities, and the high costs when doctors and nurses keep tabs on their patients, the authors say it's important to engineer social engagements that enlist the social support patients already have, and allow organizations to test their acceptability. "Concerns about privacy are often the reason doctors and hospitals avoid organizing social support," Asch says. "But while privacy is very important to some patients under some circumstances, more often patients would love if their friends and family helped them manage their diabetes, and those friends and family want to help people get their health under control."
The authors define a ladder with escalating rungs of social support ranging from no social engagement -- such as when a patient is expected to take medication as part of a routine, without anyone seeing them do it or holding them accountable -- to a design that relies on reputational or economic incentives, and incorporates teams or other designs that hold patients accountable for their health behaviors and habits.
"Although we don't normally think of competition or collaboration among patients are part of managing chronic diseases like high blood pressure, heart failure, or diabetes, research shows that behavior is contagious, and programs that take advantage of these naturally occurring relationships can be very effective," said co-author Roy Rosin, MBA, chief innovation officer at Penn Medicine. "Most health care interventions are designed for the individual patient, but there's a growing body of research that shows how health care organizations can use social engagement strategy to enhance health for patients who want to be involved in group activities or team competitions aimed at improving health."
Read more at Science Daily
|Ancient inhabitants of Chaco Canyon likely had to import corn to feed the masses a thousand years ago says a new CU-Boulder study.|
CU Boulder scientist Larry Benson said the new study shows that Chaco Canyon -- believed by some archeologists to have been populated by several thousand people around A.D. 1100 and to have held political sway over an area twice the size of Ohio -- had soils that were too salty for the effective growth of corn and beans.
"The important thing about this study is that it demonstrates you can't grow great quantities of corn in the Chaco valley floor," said Benson, an adjunct curator of anthropology at the University of Colorado Museum of Natural History. "And you couldn't grow sufficient corn in the side canyon tributaries of Chaco that would have been necessary to feed several thousand people.
"Either there were very few people living in Chaco Canyon, or corn was imported there."
A paper by Benson was published online in the Journal of Archaeological Science: Reports.
Between the ninth and 12th centuries, Chaco Canyon (officially the Chaco Culture Natural Historic Park) located in the San Juan Basin in north-central New Mexico was the focus of an unprecedented construction effort, said Benson. At the height of its cultural heyday, 12 stone masonry "great houses" and other structures were built there, along with a network of ceremonial roads linking Chaco with other Pueblo sites in the Southwest.
As part of the study, Benson used a tree ring data set created by University of Arizona Professor Emeritus Jeff Dean that showed annual Chaco Canyon precipitation spanning 1,100 years. The tree rings indicate the minimum amount of annual precipitation necessary to grow corn was exceeded only 2.5 percent of the time during that time period.
Benson suggests that much of the corn consumed by the ancient people of Chaco may have come from the Chuska Slope, the eastern flank of the Chuska Mountains some 50 miles west of Chaco Canyon that also was the source of some 200,000 timbers used to shore up Chaco Canyon masonry structures. Between 11,000 and 17,000 Pueblo people are thought to have resided on the Chuska Slope prior to A.D. 1130, he said.
Winter snows in the Chuska Mountains would have produced a significant amount of spring snowmelt that was combined with surface water features like natural "wash systems," said Benson. Water concentrated and conveyed by washes would have allowed for the diversion of surface water to irrigate large corn fields on the Chuska Slope, he said.
Benson said the Chaco Canyon inhabitants traded regularly with the Chuska Slope residents, as evidenced by stone tool material (chert), pottery and wooden beams.
"There were timbers, pottery and chert coming from the Chuska region to Chaco Canyon, so why not surplus corn?" asks Benson, a former U.S. Geological Survey scientist.
Read more at Science Daily
The sun as well as the rest of the solar system was born from a cloud of gas and dust about 4.6 billion years ago. According to previous research, some event disturbed this cloud, prompting a gravitational collapse that formed the sun and a surrounding disk of matter, where the planets were born.
By searching for telltale patterns that have been left in matter from the dawn of the solar system, Yong-Zhong Qian, co-author of the new study and an astrophysicist at the University of Minnesota in Minneapolis, and his colleagues now suggest that the explosive death of a small star could have kicked off that collapse.
Prior work has suggested that a supernova's shock wave might have packed enough energy to compress the preexisting cloud of dust. And researchers have searched for evidence of that blast: Supernovas generate telltale patterns of unstable, short-lived radioactive isotopes. The discovery of the signatures of such anomalies in ancient rocks would help confirm the idea that a supernova triggered the solar system's formation. (The isotopes of an element have different numbers of neutrons. A different number at the end of the isotope's name identifies each variety: for example, beryllium-9 or beryllium-10.)
Until now, researchers have failed to find the fingerprints of these isotopic anomalies in ancient meteorites that were left over from the birth of the solar system. However, researchers had been examining supernovas from relatively high-mass stars — those that are 15 or more times the sun's mass, Qian told Space.com. Qian's group chose to model lower-mass supernovas instead, from stars that are 12 times the sun's mass or less, and they investigated what isotopes would be formed from those explosions. They focused on the production of beryllium-10, an isotope that is commonly found in meteorites. Its prevalence in meteorites was already a mystery for researchers, Qian said. One theory held that high-energy cosmic rays could have stripped away protons or neutrons from atomic nuclei to create the beryllium-10 — a process called spallation.
Using new supernova models, Qian and his colleagues found that a low-mass supernova could generate vast amounts of ghostly particles known as neutrinos, whose influence on atomic nuclei could have created beryllium-10 — which would explain the high levels of that isotope in the meteorite record.
Moreover, the researchers said that the influence of a low-mass supernova might also explain the presence of other short-lived isotopes that are also found in meteorites, such as calcium-41 and palladium-107. "A low-mass supernova can explain the wide range of data that we have," Qian told Space.com.
Qian noted that the study group's findings do not explain the presence of all short-lived isotopes that are found in meteorites. "We think that some of these other short-lived nuclei might have been contributed by other mechanisms," Qian said. "I don't think that should be taken as a weakness of our model — it's just that our model cannot explain everything. Our work is a major piece of the puzzle about the solar system's formation, but there are other pieces of the puzzle that should be looked at as well."
Read more at Discovery News
Dec 29, 2016
The Chinchorro were a hunting and fishing people who lived from 10,000 to 3,400 B.C. on the Pacific coast of South America, at the edge of the Atacama desert.
They were among the first people in the world to mummify their dead. Their mummies date back some 7,400 years — at least 2,000 years older than Egypt's.
Now, researchers are hoping to use modern medical technology to reconstruct what they looked like in life, decode their genes and better understand the mysteries of this ancient civilization.
The 15 Chinchorro mummies, mostly children and unborn babies, were put through a CT scanner at the Los Condes clinic in the Chilean capital.
"We collected thousands of images with a precision of less than one millimeter," said chief radiologist Marcelo Galvez.
"The next phase is to try to dissect these bodies virtually, without touching them, which will help us preserve them for another 500,000 years."
Using high-tech computer processing, researchers are busy reconstructing the mummies' muscles and facial features.
"We want to see what they physically looked like, to reconstruct them and bring to life someone who died thousands of years ago," said Galvez.
Researchers are also hoping to learn more about how the Chinchorro mummified their dead.
The Chinchorro, who apparently had a complex understanding of human anatomy, would carefully remove the skin and muscles of the deceased.
Using wood, plants and clay, they reconstructed the body around the remaining skeleton, then sewed the original skin back on, adding a mouth, eyes and hair.
A mask was then placed over the face.
The result looks like something in between a statue and a person — eerily lifelike even after thousands of years.
All in the family
Mummification was an intimate process for the Chinchorro, said Veronica Silva, the head of the anthropology department at Chile's National Museum of Natural History.
"The family itself would make the mummy," she told AFP.
The earliest mummies were unborn fetuses and newborns, she said.
The mummies were all made using the same basic process, but each one shows unique "technological and artistic innovations," she said.
Read more at Discovery News
So, should this up-sizing logic continue, by "Star Wars Episode X," can we can expect the Dark Side to build a galaxy-sized superweapon that could vaporize any galactic neighbor with the flick of a switch?
This might sound far fetched, and probably a fairly horrible premise for a "Star Wars" story line, but it seems Mother Nature may be a little more forward-thinking than Emperor Palpatine and the Hubble Space Telescope has already spotted a fully operational galaxy-sized mega-laser.
Though it might not look like much, the galaxy pictured here hosts a "megamaser." Megamasers, besides sounding awesome, are basically "astronomical lasers" that produce intense emissions of microwaves that originate from the stimulated emission of microwaves from the interstellar clouds contained within the cores of galaxies. Their smaller cousins, stellar masers, can be found throughout our galaxy and are often produced in star-forming nebulae. For example, interstellar water molecules are known to produce specific frequencies that appear very bright in radio observations of the cosmos.
Megamasers, however, are in a league of they own, generating around a 100 million times more energy than regular Milky Way masers.
This observation of IRAS 16399-0937, a galaxy located over 370 million light-years from Earth, was imaged by Hubble's Advanced Camera for Surveys (ACS) and Near Infrared Camera and Multi-Object Spectrometer (NICMOS). Though it may look fairly passive and peaceful, it's generating powerful microwave radiation, making it an important astronomical curiosity.
IRAS 16399-0937 is actually known to contain two nuclei, possibly revealing that it was once two galaxies that have merged together. The northern nucleus is known to contain a supermassive black hole 100 million times the mass of our sun. Also, the southern nucleus is a very active "starburst" region, pooping-out baby stars at a speedy rate, whereas the northern nucleus appears to be devoid of star formation. With the help of Hubble's NICMOS, astronomers have been able to resolve each nucleus spiraling in toward one another.
Read more at Discovery News
As reported by Spaceweather.com, NASA's Solar Dynamics Observatory (SDO) has been tracking a dark region in the sun's lower corona rotate into view. Coronal holes are associated with streams of fast-moving superheated plasma that emerges from the sun's interior and then accelerated into space, following magnetic fields that reach from the lower corona and flow out into interplanetary space.
As the sun rotates, it sweeps magnetic streams out into the solar system, like a spinning garden sprinkler, sending these high-energy particles along with it as the fast solar wind. The sun also sweeps out slow-moving streams of plasma (the slow solar wind), which can create a barrier to these fast streams. The regions where these two streams interact are known as co-rotating interaction regions (CIRs) and they are known to cause plasma to "bunch up", creating dense flows of shocked plasma. And as we are basically staring into a fast stream's sprinkler's head, a CIR is likely on its way.
The SDO observes the sun's hot atmosphere through many different filters that are sensitive to different wavelengths of light. Each wavelength represents a different plasma temperature and in the observation above, the SDO is looking at plasma that is glowing at a temperature of 2.25 million Fahrenheit (1.25 million Kelvin). At this wavelength, coronal holes become obvious — they appear dark as the density of plasma is very low (as the particles are being lost to space very quickly); bright regions are dense with plasma at this temperature as they are trapped in closed magnetic field lines, features known as coronal loops.
Typically, solar wind particles in fast streams coming from coronal holes take a couple of days to travel from the sun to the Earth, so by using these SDO observations, solar physicists can make predictions as to what might happen when a CIR washes over Earth. Although we can expect more dramatic impacts if the sun unleashed an explosive event, like a coronal mass ejection or solar flare, CIRs are known to intensify space weather conditions, likely sparking auroras.
When solar particles hit our planet's powerful magnetic field, these electrically charged particles (known as ions) are deflected by the global magnetosphere and channeled to polar regions where Earth's magnetic field passes into the planet's crust. When a solar storm hits, these particles rain through the Earth's atmosphere at high latitudes, hitting atmospheric gases. This is when the magic happens. As solar plasma hits the atmosphere, light is produced. This light is known as the aurora. And as we are seeing this coronal hole emerge now, it could mean auroral activity on New Year's Eve.
Read more at Discovery News
A veterinarian at the Animal Care Center's of NYC's Manhattan shelter whose work involved gathering respiratory specimens from sick cats was infected. The shelter was reportedly home to at least 45 cats infected with H7N2, the first jump of the flu strain from birds to cats.
The infected veterinarian's illness was brief and has resolved itself, according to NYC Health. More than 150 other ACC staff have been screened for H7N2, with no one else testing positive. Screenings of volunteers and those who adopted cats from the shelter have also not turned up any new cases.
NYC Health said more than 100 cats across city shelters have tested positive for H7N2, all of whom are expected to recover from the illness, which spreads quickly among cats. Until the infected cats can be quarantined and brought back to full health, the ACC sites have suspended cat adoptions.
Other ACC shelter animals, such as dogs and rabbits, have tested negative for the virus.
"Our investigation confirms that the risk to human health from H7N2 is low, but we are urging New Yorkers who have adopted cats from a shelter or rescue group within the past three weeks to be alert for symptoms in their pets," said New York Health Commissioner Mary T. Bassett in a press release. "We are contacting people who may have been exposed and offering testing as appropriate."
H7N2 is a flu virus known to circulate among birds. To date there have only been two other cases of humans becoming infected with the strain. A 2002 case in Virginia saw a worker infected while participating in culling activities centered around a poultry outbreak, while in 2003 an adult male in New York was infected. In both cases, the illnesses resolved themselves.
No cases of human-to-human infection have been reported.
Several strains of bird flu exist, including the one most deadly to humans, H5N1. Culls of suspect bird populations have typically been performed in response to outbreaks. Recently The Netherlands killed some 190,000 ducks, while South Korea has culled an estimated 700,000 birds to contain the H5N6 strain. France, for its part, has detected the H5N8 strain in wild ducks.
According to the U.S. Centers for Disease Control (CDC), H7N2 spreads among cats just as human flu spreads among people: through direct contact, via airborne droplets from coughing or sneezing, and contact with contaminated surfaces. It can jump to humans from cats when people contact the animal and then touch their eyes, nose, or mouth. Airborne droplets from a cat's sneeze or cough could also reach a human's nose, mouth or eyes.
The agency says influenza in cats is not common and typically only produces a mild illness. Symptoms of a flu in cats include sneezing, coughing, fever, eye or nose discharge, lethargy and loss of appetite. Persistent coughing, lip smacking, runny nose, and fever have proven to be the hallmark symptoms displayed by the New York shelter cats that were infected with H7N2.
Read more at Discovery News
Neanderthal DNA Purged From Our Genomes
Another Neanderthal extinction is taking place, and it's happening in our genomes, according to research that found natural selection is slowly removing Neanderthal genetic variants from modern populations. The study, published in PLOS Genetics, helps to explain what happened to all of those other Neanderthal genetic signatures that were more evident right after our species — known as anatomically modern humans, or AMH — mated with Neanderthals.
"So the first generation of hybrids would have been half Neanderthal and half AMH because they had one Neanderthal parent and one AMH parent," said senior author Graham Coop, a professor at UC Davis. "Later generations of hybrids may have more or less Neanderthal ancestry depending on whether they had more Neanderthal or AMH ancestors [for example, great grandparents]."
Neanderthal-Human Sex Happened Earlier Than Thought
A child conceived 100,000 years ago from a Neanderthal and modern human mating was announced in early 2016. The woman, from Siberia, was clearly a Neanderthal, but she retained DNA from our species. It's been known that people of European and Asian ancestry today possess a small amount of Neanderthal DNA in their genomes, but the Neanderthal woman offered the first evidence that gene flow from interbreeding went from modern humans into Neanderthals as well.
The study, published in the journal Nature, "is also the first to provide genetic evidence of modern humans outside Africa as early as 100,000 years ago," said Sergi Castellano, who co-led the research and is a scientist at the Max Planck Institute for Evolutionary Anthropology.
Neanderthals Could Have Domesticated Dogs
|Many of the earliest dogs resembled this modern Siberian husky.|
"Dogs were domesticated by hunter gatherers, prior to the advent of agriculture," Frantz said. "Dogs most likely provided multiple services to humans, such as facilitating hunting or providing protection."
The researchers can't yet rule out that Neanderthals or some other ancient human first domesticated dogs. Other research teams have found possible dog remains going back to the Neanderthal era.
Homo Erectus Walked Like a Man
Right-Handed Homo habilis
Co-author David Frayer of the University of Kansas explained that, among the network of deep striations found only on the lip face of the upper front teeth, most cut marks veered from left down to the right. Analysis of the marks makes it likely they came from when the individual used a tool with his right hand to cut food he was holding in his mouth while pulling with the left hand, he said in a press release. The scratches can be seen with the naked eye, but a microscope was used to further investigate them.
Neanderthal Diet: 80 Percent Meat, 20 Percent Fruit and Veg
"Previously, it was assumed that the Neanderthals utilized the same food sources as their animal neighbors," Bocherens said in a press release. "However, our results show that all predators occupy a very specific niche, preferring smaller prey as a rule, such as reindeer, wild horses or steppe bison, while the Neanderthals primarily specialized on the large plant-eaters such as mammoths and woolly rhinoceroses."
Neanderthals also ate fruits, vegetables and other plants, the researchers determined.
Clues to Hobbit Human Relatives and Disappearance
Aida Gómez-Robles, a scientist at George Washington University specializing in human evolution, told Seeker the research demonstrates "that the origin of Homo floresiensis is very old, which confirms that this is a totally valid species with old evolutionary roots."
We also learned that humans were on Hobbit turf at around the same time that Homo floresiensis seemingly disappeared from the face of the earth. The evidence is a pair of 46,000-year-old human teeth found in Flores' Liang Bua cave. Could our appearance and the Hobbits' disappearance just be a coincidence? The discovery would seem to implicate our species in whatever happened to the Hobbits.
Many People Today Could Be Part Denisovan
|Schoolchildren from Bhutan.|
"There are certain classes of genes that modern humans inherited from the archaic humans with whom they interbred, which may have helped the modern humans to adapt to the new environments in which they arrived," said senior author David Reich, a geneticist at Harvard Medical School. "On the flip side, there was negative selection to systematically remove ancestry that may have been problematic from modern humans. We can document this removal over the 40,000 years since these admixtures occurred."
In terms of helping modern humans, Denisovans are known to have given people from Tibet and nearby regions genetic adaptations for life at high altitudes.
Denisovans Gave Some People Cold Tolerance Too
He added, "The gene is also involved in a number of other traits, like body fat distribution, bone and facial morphology (structure)."
Read more at Discovery News
Dec 28, 2016
The "brain library" at the Santo Toribio de Mogrovejo Hospital in Lima has a massive collection of diseased and healthy brains, giving researchers and also the general public a glimpse of what is going on inside our heads.
It is the only museum in Latin America, and one of the few in the world, with a large collection of brains that is regularly open to the public. The hospital, which was founded more than three centuries ago, has a total of 2,912 brains collected over the years, nearly 300 of which are on display in a mind-opening exhibit. Some 20,000 people visit the museum each year.
"Touch a real skull," the museum invites them on arrival, proffering a specimen so visitors can feel the cranial bone structure and imagine how it holds two square meters (22 square feet) of intricately folded brain matter.
The brains of this operation, so to speak, is neuropathologist Diana Rivas, who is hovering over an icy steel table choosing scientifically interesting specimens to add to the museum's collection.
"This is where we do the autopsies. I handle them myself," she tells AFP, barely looking up from the brain she is holding in her gloved hands.
She has just removed this particular specimen from a jar of formaldehyde. It is about the size of a deflated football, and "has the consistency of a rubber eraser," she says.
She examines the brain's two hemispheres, which resemble giant walnuts, then carefully removes the thin layer of three membranes that hold them together, the meninges.
Once open, the organ's fascinating geography is on full display: a labyrinth of gray and white tissue that holds the mysteries of thought, language and virtually every bodily function inside.
Rivas gives a lesson as she dissects.
"A human brain weighs between 1.2 and 2.4 kilos (2 pounds 10 ounces and five pounds four ounces), depending on the height and weight of the person, and on the sex," she says. "Women's are more evolved than men's. What differentiates us is the evolution of language, which we use much more than men."
The museum is divided into three parts: neuroanatomy, birth defects and brain damage caused by diseases such as cancer, Alzheimer's and the Zika virus.
"We show students what a healthy brain looks like, and then a sick brain, like this one with cysticercosis, which causes convulsions," she says, pointing to a brain stained with marks left by invading tapeworms.
The parasites are present in pork and can also be transmitted when people fail to wash their hands properly, she explains.
Offering more food for thought, she points to another sick brain affected by arteriosclerosis -- the result of eating too much fatty food, which clogs the arteries, including the ones feeding the brain.
"This is to remind us not to get carried away with the hamburgers. It's not good to abuse fatty foods," she says, pointing out the brain's blackened blood vessels.
Read more at Discovery News
Shanghai Customs found around 3.1 tonnes (3.4 tons) of pangolin scales mixed in with a container of wood products imported from Nigeria, state broadcaster CCTV reported Tuesday.
It estimated up to 7,500 of the creatures could have been killed.
The reclusive pangolin has become the most trafficked mammal on Earth due to soaring demand in Asia for their scales for traditional medicine and their flesh, considered a delicacy.
State media have previously said the scales fetch around 5,000 yuan (US $700) per kilogram (US $700) on the black market – which would make the seizure worth more than $2 million.
Although the international pangolin trade is illegal in China and they are listed as one of the most-protected wild animals, law enforcement remains weak.
Pangolins are also farmed in the country and an online site selling traditional Chinese medicine offers them at 7,000 yuan per kilogram.
The scales are nothing more than keratin, the same substance that makes up fingernails. Yet it has been falsely touted as a cure for multiple ailments, including cancer, among some practitioners of traditional Chinese medicine.
Shanghai Customs arrested three suspects who were suspected of smuggling the scales from Africa since 2015, the report said.
From Discovery News
As Cassini is now making some danger-close passes of the gas giant's rings ahead of its "Grand Finale", it's setting itself up for some pretty magnificent (and unprecedented) views of Saturn's moons and rings. During its third ring-grazing orbit, Cassini was able to image Pandora, one of Saturn's innermost moons, from a record-breaking distance of only 25,200 miles (40,500 kilometers), 6,800 miles (10,900 kilometers) closer than its previous closest approach in 2005. The spacecraft's narrow-angle camera captured this view on Dec. 18.
Pandora was discovered in 1980 after analysis of photos taken by the Voyager 1 probe during its grand tour of the solar system's planets. The moon measures only 52 miles (84 kilometers) across and is known to have at least two large craters around 19 miles (30 kilometers) wide. These large craters are filled with debris and a thick layer of dust covers its surface, smoothing over the smaller craters.
The moon orbits Saturn at an average distance of around 88,000 miles and zooms around the planet once every 15 hours.
This observation will be used to better understand how Pandora formed and what it's made of. Known to have a fairly low density and high albedo (reflectivity), scientists think the moon is likely porous and composed of water ice. According to NASA, Pandora has a chaotic orbit that is heavily influenced by orbital resonances with other moons, causing it to speed up and slow down during its path around Saturn. It is thought that Pandora's orbital weirdness may disrupt the grains of dust and debris in Saturn's thin F-ring, while "shepherd moon" Prometheus, which orbits just inside of the ring, works to keep the ring particles in check.
Read more at Discovery News
A planet in its star's "habitable zone" — a region where it's not too hot or too cold for liquid water to exist on a planetary surface — was found practically in our planet's backyard this year. Called Proxima Centauri b, the planet was found during a unique campaign called Red Blue Dot where astronomers shared details of their search on social media in the first few months of 2016. The planet is believed to be about 1.3 times the mass of the Earth and orbiting about 5 percent of the Earth-sun distance from its cool parent star. The team was led by Guillem Anglada-Escudé, from Queen Mary University of London.
|Artist's impression of the dwarf star TRAPPIST-1 and its three planets, which are similar in size and temperature to Venus and Earth.|
3) Planet rings spinning the wrong way
|Artist's impression of the bizarre ring system of J1407b.|
4) Three planets around two close stars
|Artist's impression of three planets orbiting two close binary stars.|
5) One planet orbiting three stars
|Artist's impression of a planet in the HD 131399 system, orbiting three stars.|
6) Kepler's new mission yields 100-plus exoplanets
|Artist's impression of the Kepler space telescope on its K2 mission.|
7) Kepler's database yields more than 1,200 exoplanets
|Artist's impression of some of the Kepler's many planetary discoveries.|
8) Baby planet just 11 million years old
|Artist's impression of a young planet orbiting the star K2-33.|
Read more at Discovery News
Dec 27, 2016
By grabbing various types of atoms and putting them together LEGO-style, the new technique could potentially be used to build tiny wires for a wide range of applications, including fabrics that generate electricity, optoelectronic devices that employ both electricity and light, and superconducting materials that conduct electricity without any loss. The scientists reported their results today in Nature Materials.
"What we have shown here is that we can make tiny, conductive wires of the smallest possible size that essentially assemble themselves," said Hao Yan, a Stanford postdoctoral researcher and lead author of the paper. "The process is a simple, one-pot synthesis. You dump the ingredients together and you can get results in half an hour. It's almost as if the diamondoids know where they want to go."
The Smaller the Better
Although there are other ways to get materials to self-assemble, this is the first one shown to make a nanowire with a solid, crystalline core that has good electronic properties, said study co-author Nicholas Melosh, an associate professor at SLAC and Stanford and investigator with SIMES, the Stanford Institute for Materials and Energy Sciences at SLAC.
The needle-like wires have a semiconducting core -- a combination of copper and sulfur known as a chalcogenide -- surrounded by the attached diamondoids, which form an insulating shell.
Their minuscule size is important, Melosh said, because a material that exists in just one or two dimensions -- as atomic-scale dots, wires or sheets -- can have very different, extraordinary properties compared to the same material made in bulk. The new method allows researchers to assemble those materials with atom-by-atom precision and control.
The diamondoids they used as assembly tools are tiny, interlocking cages of carbon and hydrogen. Found naturally in petroleum fluids, they are extracted and separated by size and geometry in a SLAC laboratory. Over the past decade, a SIMES research program led by Melosh and SLAC/Stanford Professor Zhi-Xun Shen has found a number of potential uses for the little diamonds, including improving electron microscope images and making tiny electronic gadgets.
For this study, the research team took advantage of the fact that diamondoids are strongly attracted to each other, through what are known as van der Waals forces. (This attraction is what makes the microscopic diamondoids clump together into sugar-like crystals, which is the only reason you can see them with the naked eye.)
They started with the smallest possible diamondoids -- single cages that contain just 10 carbon atoms -- and attached a sulfur atom to each. Floating in a solution, each sulfur atom bonded with a single copper ion. This created the basic nanowire building block.
The building blocks then drifted toward each other, drawn by the van der Waals attraction between the diamondoids, and attached to the growing tip of the nanowire.
"Much like LEGO blocks, they only fit together in certain ways that are determined by their size and shape," said Stanford graduate student Fei Hua Li, who played a critical role in synthesizing the tiny wires and figuring out how they grew. "The copper and sulfur atoms of each building block wound up in the middle, forming the conductive core of the wire, and the bulkier diamondoids wound up on the outside, forming the insulating shell."
A Versatile Toolkit for Creating Novel Materials
The team has already used diamondoids to make one-dimensional nanowires based on cadmium, zinc, iron and silver, including some that grew long enough to see without a microscope, and they have experimented with carrying out the reactions in different solvents and with other types of rigid, cage-like molecules, such as carboranes.
The cadmium-based wires are similar to materials used in optoelectronics, such as light-emitting diodes (LEDs), and the zinc-based ones are like those used in solar applications and in piezoelectric energy generators, which convert motion into electricity.
"You can imagine weaving those into fabrics to generate energy," Melosh said. "This method gives us a versatile toolkit where we can tinker with a number of ingredients and experimental conditions to create new materials with finely tuned electronic properties and interesting physics."
Read more at Science Daily
In a new study published in the journal Scientific Reports, scientists from Tel Aviv University (TAU) captured 22 Egyptian fruit bats from a natural roost in Israel and housed them in large chambers that would allow the animals to be monitored visually and acoustically over the course of more than two months.
The goal? To find out what all of the yelling was about.
"Previous research presumed that most bat communication was based on screaming and shouting. We wanted to know how much information was actually conveyed, and we wanted to see if we could, in fact, extract that information," explained TAU study lead Yossi Yovel, in a statement.
Yovel and his team did just that. Their bat observations yielded recordings of some 15,000 vocalizations – the sum total of all the chatter passed between the bats, generating dozens of specific calls – and there was in fact a great deal of significance to the sounds.
After poring over the audio, the researchers say the calls not only identified the calling bat but also conveyed information about the bat being called. What's more, different calls were used for different situations – usually aggression-filled encounters, the team observed. Even friends or foes greeted each other with different calls.
"We have found that bats fight over sleeping positions, over mating, over food or just for the sake of fighting," said Yovel. "To our surprise, we were able to differentiate between all of these contexts in complete darkness, and we are confident bats themselves are able to identify even more information and with greater accuracy. They are, after all, an extremely social species that live with the same neighbors for dozens of years."
Read more at Discovery News
Cheetah numbers in Zimbabwe have plunged by more than 85 percent in 16 years and fewer than 50 individuals survive in Iran, the Zoological Society of London (ZSL) and Wildlife Conservation Society (WCS) warned.
The report's authors said cheetahs should be listed as "Endangered" instead of "Vulnerable" on the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species.
The study published in the Proceedings of the National Academy of Sciences, estimated that just 7,100 cheetahs remain in the wild, occupying just nine percent of the territory they once lived in.
"The cheetah is sprinting towards the edge of extinction and could soon be lost forever unless urgent, landscape-wide conservation action is taken," ZSL said in a statement.
There were an estimated 100,000 cheetahs at the beginning of the 20th century, according to previous estimates.
"Given the secretive nature of this elusive cat, it has been difficult to gather hard information on the species, leading to its plight being overlooked," said Sarah Durant, the report's lead author and project leader for the Rangewide Conservation Program for Cheetah and African Wild Dog.
"Our findings show that the large space requirements for cheetah, coupled with the complex range of threats faced by the species in the wild, meant that it is likely to be much more vulnerable to extinction than was previously thought," she said.
Cheetahs travel widely in search of prey with some home ranges estimated at up to 3,000 square kilometers (1,158 square miles).
The study found that 77 percent of the animal's remaining habitat falls outside protected areas, leaving it especially vulnerable to human interference.
The main risks are humans hunting their prey, habitat loss, illegal trafficking of cheetah parts and the exotic pet trade, according to the study.
Durant hailed recent commitments taken by the international community, including on stemming the flow of live cats from the Horn of Africa region.
Read more at Discovery News
But 2016 has also been a year of disappointments. Egyptian authorities faced embarrassment after supporting the theory that a secret room existed in the tomb of King Tut. Such a room would have concealed "one of the most important finds of the century" — the tomb of Queen Nefertiti.
After much excitement, more detailed scans earlier this year showed that no secret room existed in the tomb of the boy pharaoh.
Still in Egypt, experts raised doubts over a claim that the Great Pyramid at Giza contains two unknown voids or cavities. Investigations using innovative techniques such as infrared thermography, and "cosmic ray" muon detectors are expected further explore that claim in 2017.
Here are some of our favorite archaeology stories of this year.
Found within caves in the ancient Red Sea port of Wadi al-Jarf, the papyri provide insight into the lives of workers in the port during the reign of fourth dynasty King Khufu, also known as Cheops, for whom the Great Pyramid of Giza was built as a tomb.
The hieroglyphs reveal that workers and employees at Wadi al-Jarf participated in the construction of the pyramid.
Other findings included the remains of a 4,500-year-old funerary boat which was uncovered near the Abusir pyramids, a 3000-year-old mummy resting inside a perfectly preserved brightly colored wooden sarcophagus and a remarkable 3,400-year-old necropolis. Consisting of dozens of rock-cut tombs, it was unearthed at the quarry site of Gebel el Sisila, north of Aswan.
They confirmed that iron of the dagger placed on the right thigh of King Tut's mummified body has meteoric origins.
The legs had been on display at the Egyptian Museum in Turin, Italy when an international team of researchers led by Frank Rühli, head of the Institute of Evolutionary Medicine at the University of Zurich in Switzerland, made the stunning identification.
Nefertari's mummy was ripped to pieces and tossed around by ancient robbers, so her remains were believed to have been lost forever. Nefertari is the only queen from the Ramesside era to have been identified so far.
The settlement was home to several families who lived in a number of circular wooden houses built on stilts above a river. It was abandoned in haste 3,000 years ago as a giant fire destroyed the houses. The dwellings fell into the river, where thick silt and clay preserved the contents.
The archaeologists found an extraordinary time capsule buried just over six feet below the ground surface. Finds include clothing, jewelry, tools, furniture, textiles, abandoned meals still in the cooking pots and the the oldest, largest, most complete wheel ever found in Britain.
Evidence for one of the most common mistakes in the kitchen — burning food — was found in a 3,000-year-old clay pot that was excavated in central Jutland, Denmark, at the bottom of what was once a waste pit. The clay vessel, in near mint condition, contained burned cheese and was possibly thrown in a moment of anger over the cooking mistake.
Such cooking accidents were likely avoided by those using the "Cumanae testae" or "Cumanae patellae" — pans produced more than 2,000 years ago in the from the city of Cumae, about 12 miles west of Naples. Archaeologists found the site where such pottery, featuring a red coating that prevented food from sticking to the pan, was produced. They were the precursors of non-stick pans.
While 340-year-old Roquefort cheese was found in a Swedish shipwreck on the bed of the Baltic, turf cutters working in an Irish peat bog unearthed a 2,000-year-old lump of butter, which also smelled like a strong cheese.
Chemical analysis of prehistoric hearths, revealed that salmon has been on the American menu for 11,800 years. The dating confirms central Alaska as the earliest site of salmon consumption in the Americas.
As for drinking, researchers analyzing ancient pottery jars in China, found that barley might have been the "secret ingredient" in a 5,000-year-old beer recipe.
|World's oldest dress|
The year also brought the discoveries of the world's oldest gold artifact — a tiny bead unearthed in Bulgaria which archaeologists believe is 6,500 years old — and the oldest snowshoe. Found in the Italian Alps, it looks amazingly modern even though it dates back 5,800 years.
|Huge ancient ship graveyard found off Greek islands|
Investigation of the Fourni archipelago, a collection of 13 islands and islets located between the eastern Aegean islands of Samos and Icaria, revealed 23 ancient wrecks, which add to 22 other wrecks identified in 2015. The discovery confirms the Greek site as the ancient shipwreck capital of the world.
Still in Greece, archaeologists unearthed a human skeleton dating back to 2,000 years ago on the Antikythera shipwreck. Dubbed the "Titanic of the ancient world," the vessel sank more than 2,000 years ago off the remote island of Antikythera, in southern Greece.
Found by Greek sponge divers more than 100 years ago, the wreck contained a mysterious "Antikythera mechanism" — a complex, geared astronomical calculator known as the world's oldest computer.
The remains, which most likely belonged to a young man, could yield the first DNA from an ancient shipwreck victim.
Researchers rewrote the history of smallpox by analyzing the mummified remains of a 17th-century child from Vilnius, Lithuania.
The disease had long been thought to have appeared in human populations thousands of years ago, but the child mummy, which turned to contain the oldest known sample of the variola virus that causes smallpox, now challenges that timeline,placing it between 1643 and 1665.
One of the most spectacular investigations involved Ötzi the Iceman, whose voice was reconstructed by scientists with the "best possible approximation."
Presented during a major congress to celebrate the 25th anniversary of the discovery of the 5,300-year-old mummy, the experiment aimed to discover the tone of the Iceman's Stone Age vowels.
Ötzi broke his silence with a deep male voice. He spoke Italian — but just vowels, as you can hear here.
Read more at Discovery News