Ereditato is the former leader of the 160 physicists from 13 countries that compose the OPERA collaboration, whose goal is to study neutrino physics. It was first proposed in 2000, and Ereditato led it from 2008 to 2012. Then in late winter of 2011, the impossible seemed to happen. “The guy who is looking at the data calls me,” Ereditato tells me from my computer screen. “He says, ‘I see something strange.’ ” What he saw was evidence that neutrinos traveled through 454 miles of Earth’s crust, from Switzerland to Italy—which they are supposed to do—at such a high speed that they arrived 60.7 nanoseconds faster than light could travel that distance in outer space—which should have been impossible.

Over the last century, Einstein’s observation that no massive object can travel faster than the speed of light in a vacuum, enshrined in his theory of special relativity, has become a keystone of how we understand the universe. If the OPERA measurement was correct, it would mark the first-ever violation of that theory: An atom bomb in the heart of our understanding of the universe.

I ask Ereditato if he thought it must have been a mistake. “I don’t think it’s fair to say this,” Ereditato tells me. “If we say that, we bias our analysis. So when we got this indication that something was so astonishing, the first reaction was, well, let’s find why this is so.”

Wolfgang Pauli postulated the existence of neutrinos in 1930 to solve a simple problem. When nuclei undergo beta decay through the emission of an electron or a positron, the electron’s antimatter equivalent, something is missing. Either something invisible is emitted along with the electron or positron, or energy must disappear. Since no repeatable experiment of anything flying, falling, moving, colliding, decaying, or staying put had ever seen energy disappear, Pauli proposed the neutrino, an invisible particle with all the properties necessary to bring beta decay into accord with the first law of thermodynamics. By invisible, I mean that when neutrinos pass through matter they rarely leave a trace. So rarely that it took almost 30 years before an experiment (by Frederick Reines and Clyde Cowan) found physical evidence of them.

Today, neutrinos are an integral part of the Standard Model’s periodic table of particle physics. Here you’ll find the particles that make up matter listed in pairs separated into three categories: electron neutrinos are paired with electrons, muon neutrinos with muons, and tau neutrinos with, you guessed it, taus. Neutrinos can morph from one flavor into another. For example, an electron neutrino can oscillate into a muon neutrino, and a muon neutrino can flip into a tau neutrino. “Neutrino oscillations are the first indication of physics beyond the Standard Model,” Ereditato tells me. Laughing, he adds, “That’s the reason why I like neutrinos.”

http://nautil.us/issue/24/error/the-data-that-threatened-to-break-physics

posted by f. sheikh

For years, scientists have noticed an interesting pattern of cancer among children. Those who went to day care early in life were less likely to later develop the most common childhood cancer: acute lymphoblastic leukemia (ALL). Now, a 7-year study appears to have unraveled the molecular mechanism driving ALL. The work may explain why early exposure to infections in places such as day cares seems to protect against the disease and why unrelated vaccines help guard against this cancer.

For Mel Greaves, a cancer cell biologist at the University of London’s Institute of Cancer Research, the finding provides an explanation for the hypothesis he has long promoted: that when infants in modern societies are sheltered from routine infections, their immune systems are more likely to overreact during later infections, paving the way for ALL. “I see it as the missing link,” he says of the new research.

Most childhood ALL involves a malfunction of B cells, the scouts of the immune system that patrol the bloodstream looking for intruders like viruses and bacteria; they make antibodies that help fight infections. But with leukemia, the immune system goes haywire, churning out flawed, immature B cells at a prodigious rate and crowding out healthy blood cells.

Normal B cells are a marvel of adaptability. As they mature, they reprogram their own DNA, enabling the immune system to produce millions of different B cells programmed to recognize the vast range of potential infections. The DNA rearrangement relies on a sequence of enzymes. First, proteins known as RAGs cut and paste whole chunks of DNA. After that, another enzyme, AID, goes to work “fine-tuning” the DNA by altering single nucleotides.

But Greaves and colleagues suspected this process could go awry, introducing mutations that create flawed B cells that could cause leukemia. In a series of experiments, they found evidence that much of the problem lay with a breakdown in the orderly sequence of gene editing during infections. Rather than the RAGs doing their business and then stepping aside for the AID, the AID kicked in simultaneously, potentially increasing the risk of gene-editing errors. Click link below for full article;

http://news.sciencemag.org/biology/2015/05/study-may-explain-mysterious-cancer-day-care-connection

posted by f. sheikh

Most of us think of Europe as the ancestral home of white people. But a new study shows that pale skin, as well as other traits such as tallness and the ability to digest milk as adults, arrived in most of the continent relatively recently. The work, presented here last week at the 84th annual meeting of the American Association of Physical Anthropologists, offers dramatic evidence of recent evolution in Europe and shows that most modern Europeans don’t look much like those of 8000 years ago.

The origins of Europeans have come into sharp focus in the past year as researchers have sequenced the genomes of ancient populations, rather than only a few individuals. By comparing key parts of the DNA across the genomes of 83 ancient individuals from archaeological sites throughout Europe, the international team of researchers reported earlier this year that Europeans today are a mix of the blending of at least three ancient populations of hunter-gatherers and farmers who moved into Europe in separate migrations over the past 8000 years. The study revealed that a massive migration of Yamnaya herders from the steppes north of the Black Sea may have brought Indo-European languages to Europe about 4500 years ago.

Now, a new study from the same team drills down further into that remarkable data to search for genes that were under strong natural selection—including traits so favorable that they spread rapidly throughout Europe in the past 8000 years. By comparing the ancient European genomes with those of recent ones from the 1000 Genomes Project, population geneticist Iain Mathieson, a postdoc in the Harvard University lab of population geneticist David Reich, found five genes associated with changes in diet and skin pigmentation that underwent strong natural selection.

First, the scientists confirmed an earlier report that the hunter-gatherers in Europe could not digest the sugars in milk 8000 years ago, according to a poster. They also noted an interesting twist: The first farmers also couldn’t digest milk. The farmers who came from the Near East about 7800 years ago and the Yamnaya pastoralists who came from the steppes 4800 years ago lacked the version of the LCT gene that allows adults to digest sugars in milk. It wasn’t until about 4300 years ago that lactose tolerance swept through Europe.

When it comes to skin color, the team found a patchwork of evolution in different places, and three separate genes that produce light skin, telling a complex story for how European’s skin evolved to be much lighter during the past 8000 years. The modern humans who came out of Africa to originally settle Europe about 40,000 years are presumed to have had dark skin, which is advantageous in sunny latitudes. And the new data confirm that about 8500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin: They lacked versions of two genes—SLC24A5 and SLC45A2—that lead to depigmentation and, therefore, pale skin in Europeans today.

http://news.sciencemag.org/archaeology/2015/04/how-europeans-evolved-white-skin?utm_source=facebook&utm_medium=social&utm_campaign=facebook

 posted by f. sheikh