A new study, led by researchers at the University of Cambridge and reported in the journal Physical Review D, suggests that some unexplained results from the XENON1T experiment in Italy may have been caused by dark energy, and not the dark matter the experiment was designed to detect.

They constructed a physical model to help explain the results, which may have originated from dark energy particles produced in a region of the Sun with strong magnetic fields, although future experiments will be required to confirm this explanation. The researchers say their study could be an important step toward the direct detection of dark energy.

Everything our eyes can see in the skies and in our everyday world—from tiny moons to massive galaxies, from ants to blue whales—makes up less than five percent of the universe. The rest is dark. About 27% is dark matter—the invisible force holding galaxies and the cosmic web together—while 68% is dark energy, which causes the universe to expand at an accelerated rate.

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The five-decade-old paradox — long thought key to linking quantum theory with Einstein’s theory of gravity — is falling to a new generation of thinkers. Netta Engelhardt is leading the way.

As the world grapples with the hyper-infectious Delta coronavirus variant, scientists are racing to understand the biological basis for its behaviour.

A slew of studies has highlighted an amino-acid change present in Delta that might contribute to its swift spread. Delta is at least 40% more transmissible than is the Alpha variant identified in the United Kingdom in late 2020, epidemiological studies suggest.

“The key hallmark of Delta is that transmissibility seems to be ramping up to the next notch,” says Pei-Yong Shi, a virologist at the University of Texas Medical Branch in Galveston. “We thought Alpha was pretty bad, very good at spreading. This one seems to be even more.”

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For the purpose of analyzing observed phenomena, it has been convenient, and thus far sufficient, to regard gravity as subject to the deterministic principles of classical physics, with the gravitational field obeying Newton’s law or Einstein’s equations. Here we treat the gravitational field as a quantum field and determine the implications of such treatment for experimental observables. We find that falling bodies in gravity are subject to random fluctuations (“noise”) whose characteristics depend on the quantum state of the gravitational field. We derive a stochastic equation for the separation of two falling particles. Detection of this fundamental noise, which may be measurable at gravitational wave detectors, would vindicate the quantization of gravity, and reveal important properties of its sources.

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Lawrence Livermore National Laboratory (LLNL) announced today that it has produced a fusion reaction in the laboratory that yielded more energy than was absorbed by the fuel to initiate it.

Zapping a BB-size capsule of fusion fuel with UV light from 192 lasers at the lab’s $3.5 billion National Ignition Facility (NIF), scientists say they sparked fusion reactions that released 1.3 megajoules of energy, about five times the 250 kilojoules that were absorbed by the capsule. That energy emission from the tiny blob of plasma—roughly a cube with sides measuring the width of a human hair—occurred within about 100 trillionths of a second to yield more than 1016 watts of power.

The shot, which occurred on 8 August, demolished the facility’s previous record yield of 170 kJ, observed in February, and was 25 times as high as the best results obtained just a year ago. “Everyone has a spring in their step,” says NIF director Mark Herrmann. The results have not yet been peer reviewed.

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The Philippine ethnic group Ayta Magbukon has the highest proportion of genes from our extinct relatives, the Denisovans, a new study led by Uppsala University shows. Their Denisovan share far exceeds that of ethnic groups in Papua New Guinea, who previously held the record. The study is published in the scientific journal Current Biology.

The Denisovans became known to science in 2010 with the sequencing of DNA from finger bones and teeth found in the Denisova Cave in Siberia. Despite good genetic information, who these people were remains a mystery, since only small bone fragments and teeth from them have been found. Scientists therefore use DNA technology in their quest to find out where the Denisovans lived, what they looked like and what happened to them. Today, thanks to these analyses, we know that they interbred both with our ancestors and with Neanderthals and, accordingly, that Denisovan genes, just like Neanderthal ones, are found in present-day humans. Among the inhabitants of parts of Oceania, in particular, the Denisovan genetic inheritance makes up a higher proportion of the genome than the genetic traces left by the Neanderthals do in modern humans.

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At Abu Hureyra (AH), Syria, the 12,800-year-old Younger Dryas boundary layer (YDB) contains peak abundances in meltglass, nanodiamonds, microspherules, and charcoal. AH meltglass comprises 1.6 wt.% of bulk sediment, and crossed polarizers indicate that the meltglass is isotropic. High YDB concentrations of iridium, platinum, nickel, and cobalt suggest mixing of melted local sediment with small quantities of meteoritic material. Approximately 40% of AH glass display carbon-infused, siliceous plant imprints that laboratory experiments show formed at a minimum of 1200°–1300 °C; however, reflectance-inferred temperatures for the encapsulated carbon were lower by up to 1000 °C. Alternately, melted grains of quartz, chromferide, and magnetite in AH glass suggest exposure to minimum temperatures of 1720 °C ranging to >2200 °C. This argues against formation of AH meltglass in thatched hut fires at 1100°–1200 °C, and low values of remanent magnetism indicate the meltglass was not created by lightning. Low meltglass water content (0.02–0.05% H2O) is consistent with a formation process similar to that of tektites and inconsistent with volcanism and anthropogenesis. The wide range of evidence supports the hypothesis that a cosmic event occurred at Abu Hureyra ~12,800 years ago, coeval with impacts that deposited high-temperature meltglass, melted microspherules, and/or platinum at other YDB sites on four continents.

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Humans’ ability to efficiently shed heat has enabled us to range over every continent, but a wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts. Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979. Recent exceedances of 35°C in global maximum sea surface temperature provide further support for the validity of these dangerously high TW values. We find the most extreme humid heat is highly localized in both space and time and is correspondingly substantially underestimated in reanalysis products. Our findings thus underscore the serious challenge posed by humid heat that is more intense than previously reported and increasingly severe.

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EIGHT MEMBERS OF the editorial board of a scientific journal have resigned after it published a slew of controversial papers that critics fear could be used for DNA profiling and persecution of ethnic minorities in China.

The journal, Molecular Genetics & Genomic Medicine, is the latest to be caught up in controversy involving ethically fraught research. Emails obtained by The Intercept show that the journal’s editor-in-chief has been slow to respond to queries about the papers, which involve research on Tibetans and Uyghurs, among other ethnic groups, and were first brought to her attention in March. The journal is published by Wiley, a multinational company based in New Jersey that is one of the world’s premier scientific publishers.

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Today, oxygen fuels much of life on Earth, but it wasn’t always that way. Three billion years ago, this gas was scarce in the atmosphere and oceans. Knowing why oxygen became plentiful could illuminate the evolution of our planet’s flora and fauna, but scientists have struggled to find an explanation satisfying to all. Now a research team has proposed a novel link between how fast our planet spun on its axis, which defines the length of a day, and the ancient production of additional oxygen. Their modeling of Earth’s early days, which incorporates evidence from microbial mats coating the bottom of a shallow, sunlit sinkhole in Lake Huron, produced a surprising conclusion: as Earth’s spin slowed, the resulting longer days could have triggered more photosynthesis from similar mats, allowing oxygen to build up in ancient seas and diffuse up into the atmosphere.

That proposal, described today in Nature Geoscience, has intrigued some scientists. “The rise of oxygen [on Earth] is easily the most substantial environmental change in the history of our planet,” says Woodward Fischer, a geobiologist at the California Institute of Technology who was not involved with the work. This study offers “a totally new flavor of an idea. It’s making a connection that people haven’t made before.”

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Today, the LHCb experiment at CERN is presenting a new discovery at the European Physical Society Conference on High Energy Physics (EPS-HEP). The new particle discovered by LHCb, labeled as Tcc+, is a tetraquark—an exotic hadron containing two quarks and two antiquarks. It is the longest-lived exotic matter particle ever discovered, and the first to contain two heavy quarks and two light antiquarks.

Watching X-rays flung out into the universe by the supermassive black hole at the center of a galaxy 800 million light-years away, Stanford University astrophysicist Dan Wilkins noticed an intriguing pattern. He observed a series of bright flares of X-rays – exciting, but not unprecedented – and then, the telescopes recorded something unexpected: additional flashes of X-rays that were smaller, later and of different “colors” than the bright flares.

As a newborn mammal opens its eyes for the first time, it can already make visual sense of the world around it. But how does this happen before they have experienced sight?

A new Yale study suggests that, in a sense, mammals dream about the world they are about to experience before they are even born. 

Writing in the July 23 issue of Science, a team led by Michael Crair, the William Ziegler III Professor of Neuroscience and professor of ophthalmology and visual science, describes waves of activity that emanate from the neonatal retina in mice before their eyes ever open. 

This activity disappears soon after birth and is replaced by a more mature network of neural transmissions of visual stimuli to the brain, where information is further encoded and stored. 

“At eye opening, mammals are capable of pretty sophisticated behavior,” said Crair, senior author of the study, who is also vice provost for research at Yale.” But how do the circuits form that allow us to perceive motion and navigate the world? It turns out we are born capable of many of these behaviors, at least in rudimentary form.” 

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Tomato fruits inform the mother plant when they are being eaten by caterpillars, shows a new study. Little is known about whether a fruit can communicate with the plant to which it’s attached, which could be important for warning the plant of threats. This early evidence shows that pest attacks do trigger defensive electrical and biochemical responses across the plant. This could provide more effective monitoring strategies for detecting agricultural pests in the future.

A recent study in Frontiers in Sustainable Food Systems shows that the fruits of a type of tomato plant send electrical signals to the rest of the plant when they are infested by caterpillars. Plants have a multitude of chemical and hormonal signaling pathways, which are generally transmitted through the sap (the nutrient-rich water that moves through the plant). In the case of fruits, nutrients flow exclusively to the fruit and there has been little research into whether there is any communication in the opposite direction–i.e. from fruit to plant.

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Electromagnetism has always been a subtle phenomenon. In the 19th century, scholars thought that electromagnetic waves must propagate in some sort of elusive medium, which was called aether. Later, the aether hypothesis was abandoned, and to this day, the classical theory of electromagnetism does not provide us with a clear answer to the question in which medium electric and magnetic fields propagate in vacuum. On the other hand, the theory of gravitation is rather well understood. General relativity explains that energy and mass tell the spacetime how to curve and spacetime tells masses how to move. Many eminent mathematical physicists have tried to understand electromagnetism directly as a consequence of general relativity. The brilliant mathematician Hermann Weyl had especially interesting theories in this regard. The Serbian inventor Nikola Tesla thought that electromagnetism contains essentially everything in our universe. So what is the mutual relationship of electromagnetism and gravitation? We provide one possible explanation to the riddle.

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In the search for life beyond Earth, distinguishing the living from the non-living is paramount. However, this distinction is often elusive, as the origin of life is likely a stepwise evolutionary process, not a singular event. Regardless of the favored origin of life model, an inherent “grayness” blurs the theorized threshold defining life. Here, we explore the ambiguities between the biotic and the abiotic at the origin of life. The role of grayness extends into later transitions as well. By recognizing the limitations posed by grayness, life detection researchers will be better able to develop methods sensitive to prebiotic chemical systems and life with alternative biochemistries.

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Jul 22

A research team from Osnabrück University and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, has, for the first time, observed lethal attacks by chimpanzees on gorillas in the wild. Whether this behavior is due to competition for food or to the decline of the rainforest’s productivity caused by climate change will now be investigated in more detail.

New models of neutron stars show that their tallest mountains may be only fractions of millimeters high, due to the huge gravity on the ultra-dense objects. The research is presented today at the National Astronomy Meeting 2021.

Neutron stars are some of the densest objects in the Universe: they weigh about as much as the Sun, yet measure only around 10km across, similar in size to a large city.

In the TV series Star Trek, the Borg are cybernetic aliens that assimilate humans and other creatures as a means of achieving perfection. So when Jill Banfield, a geomicrobiologist at the University of California, Berkeley, sifted through DNA in the mud of her backyard and discovered a strange linear chromosome that included genes from a variety of microbes, her Trekkie son proposed naming it after the sci-fi aliens. The new type of genetic material was a mystery. Maybe it was part of a viral genome. Maybe it was a strange bacterium. Or maybe it was just an independent piece of DNA existing outside of cells. Whatever it is, it’s “pretty exciting,” says W. Ford Doolittle, an evolutionary biologist at Dalhousie University who was not involved with the work.

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Created on Jun 17, 2020
By @gurlic
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