But the discovery is more than just a proof of principle.
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A blazar producing gamma rays and neutrinos is likely producing other highenergy particles, too, such as protons. These ultra—high-energy cosmic rays bombard Earth from time to time, but their source has been a mystery. Now, blazars are a suspect. The IceCube team awaits more fleeting extra-galactic messengers.
But having welcomed this first visitor, it is making its case for an enlarged detector enclosing 10 times the current volume of ice. Structures can now be gleaned from micrometer-size crystals black , seen here on an electron microscope slide. Gonen Lab. Two research teams simultaneously published papers in October revealing a new way to determine the molecular structures of small organic compounds in just minutes, rather than the days, weeks, or months required by traditional methods.
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For decades, the gold standard for molecular mapping has been a technique known as x-ray crystallography, which involves firing a beam of x-rays at a crystal containing millions of copies of a molecule lined up in a common orientation. Researchers then track the way x-rays bounce off the crystal to identify individual atoms and assign them positions in the molecule. The structures are invaluable for understanding how biological molecules behave and how drugs interact with them. But the technique requires growing crystals about the size of a grain of sand, which can be a major hurdle for some substances.
In recent years, researchers have modified the diffraction technique by replacing the x-rays with an electron beam. The electron beam is aimed at a sheetlike 2D crystal of the target biomolecule, usually a protein. Two research teams—one in the United States, the other in Germany and Switzerland—found they could use such accidental crystals after all. They fired an electron beam at a tiny 3D crystal on a rotating stage and tracked how the diffraction pattern changed with each slight turn.
The technique generated molecular structures in minutes—from microscopic crystals just one-billionth the size required for x-ray studies. Well-suited for mapping small molecules such as hormones and potential drugs, the new technique should have a profound impact on fields ranging from the synthesis and discovery of new pharmaceuticals to the design of molecular probes to study and track diseases. A computer visualization of asteroid fragments falling toward Greenland. The asteroid slammed into northwestern Greenland like a fusillade of nuclear bombs, instantly vaporizing rock and sending shock waves across the Arctic.
The scar it left—a kilometer-wide impact crater called Hiawatha—is big enough to hold Washington, D. Scientists reported the startling discovery in November, after aircraft radar revealed the crater lurking beneath the kilometer-thick ice sheet. Hiawatha crater is one of the 25 largest on Earth. Though not as cataclysmic as the dinosaur-killing Chicxulub impact, which carved out a kilometer-wide crater in Mexico 66 million years ago, the Hiawatha impact could have had a powerful effect on the global climate.
Meltwater from the impact, pouring into the north Atlantic Ocean, could have sent temperatures plunging by halting a conveyor belt of currents that brings warmth to northwest Europe. The radar images suggest Hiawatha is exceptionally fresh, dating from the past , years. That would tie the impact to the Younger Dryas, a thousand-year global cooling event that began just as the world was thawing from the last ice age. It would also vindicate proponents of the controversial Younger Dryas impact theory.
A decade ago, they proposed that extraterrestrial impacts could account for hints of mayhem in the archaeological and geological record. But they could never point to a crater. The timing of this impact is far from settled. Ice cores elsewhere on Greenland, which record the past , years, contain no signs of impact debris.
A firm answer will depend on painstaking work to tease dates from the radioactive clocks in tiny mineral crystals swept from under the ice. If they show the Hiawatha impact did occur 13, years ago, it would have come just as humans were fanning across a new continent, chasing mastodons around North America. It is tempting to imagine their thoughts as they looked up to see the searing white orb of the impactor, four times brighter than the sun. Sexual harassment in science has been underreported and largely ignored until recently.
But this year brought signs of change. In June, the U. National Academies of Sciences, Engineering, and Medicine released a landmark report on sexual harassment of women in academic science, engineering, and medicine that could prove to be a watershed. And this year, several institutions took action.
Others announced policy changes. In September, the U.
And the presidents of the National Academies promised in May to explore how proven harassers could be ejected from their prestigious ranks. The pace of change is not nearly fast enough for critics. BethAnn McLaughlin, a neuroscientist at Vanderbilt University in Nashville who this year founded the advocacy group metooSTEM, notes, for example, that the National Institutes of Health NIH does not require universities to report grantees under investigation, or even disciplined, for sexual harassment.
A bone fragment found in a cave in the Denisova valley in Russia. Thomas Higham, University of Oxford. A fragment of bone from a woman who lived more than 50, years ago has revealed a startling connection between two extinct groups of archaic humans. Researchers knew Denisovans, Neanderthals, and modern humans interbred, at least occasionally, in ice age Europe and Asia. The genes of both types of archaic human are present in Asian and European people today.
And other fossils found in the Siberian cave have shown members of all three groups lived there at different times. But the new finding is intimate testimony of an encounter between a Denisovan and a Neanderthal. After sequencing DNA from the bone, researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, found it came from a female, and that her genome matched those of Denisovans and Neanderthals in roughly equal measure.
That could have been because her parents themselves had mixed ancestry. But her chromosome pairs harbored different variants—so-called heterozygous alleles—of nearly half her genes, suggesting the maternal and paternal chromosomes came from different kinds of humans. Her mitochondrial DNA, which is almost entirely inherited from the mother, was uniformly Neanderthal, so the researchers concluded she was a first generation hybrid of a Denisovan male and Neanderthal female. A closer look at the genome suggested her father also had some Neanderthal ancestry.
That suggests, the authors say, that distinct groups of Neanderthals migrated back and forth between western Europe and Siberia multiple times.
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Along the way, apparently, they freely spread their genes to outsiders. Why did Denisovans and Neanderthals remain genetically distinct? Geographic barriers probably played a role, but researchers need more ancient DNA from different sites to understand the true influence of these prehistoric couplings. Paul Kitagaki Jr. In April, police announced they had arrested a suspect in one of the coldest of cold cases: a series of rapes and murders in California in the s and s.
It was a stunning development, and so was the way investigators fingered the alleged Golden State Killer.get link
Pulling Back the Curtain on DNA Ancestry Tests
They identified his relatives by uploading a profile of DNA recovered from one of the crime scenes to a public genealogy DNA database. Law enforcement agencies have since used this strategy to crack about 20 other cold cases, ushering in a new field: forensic genealogy. Investigators uploaded a DNA profile from a rape kit to the database, and found several distant relatives of the perpetrator. Working with a genealogist, they then used public records to construct large family trees and homed in on year-old Joseph James DeAngelo, whose age and location fit some of the crimes.
All this has alarmed some ethicists and geneticists who see these familial searches as an invasion of privacy with a potential for misidentifying suspects. The long-awaited step could be the harbinger of a new class of drugs targeting diseasecausing genes. This is a great place to start looking for some hints as well as to share some ideas. Contemporary relatives show along date rings to help your children see how they are related to their cousins, uncles, and aunts.
Parents can help children take a break by locking the device, so they can re-focus, or join the family at dinner. Welcome to the official website for the Lithuanian Global Genealogical Society. Our professional genealogists have expertise and knowledge of available genealogy records worldwide to provide you with trusted personalized genealogy research services to discover your family history and ancestors.
Welcome to Family History Help We have been finding ancestors since and in that time discovered the stories and life events of thousands of people.