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Archive for the ‘particle physics’ category: Page 366

Dec 8, 2020

Complete Genomic Sequence of Human Coronavirus OC43: Molecular Clock Analysis Suggests a Relatively Recent Zoonotic Coronavirus Transmission Event

Posted by in categories: biotech/medical, genetics, health, particle physics

Coronaviruses are enveloped, positive-stranded RNA viruses with a genome of approximately 30 kb. Based on genetic similarities, coronaviruses are classified into three groups. Two group 2 coronaviruses, human coronavirus OC43 (HCoV-OC43) and bovine coronavirus (BCoV), show remarkable antigenic and genetic similarities. In this study, we report the first complete genome sequence (30,738 nucleotides) of the prototype HCoV-OC43 strain (ATCC VR759). Complete genome and open reading frame (ORF) analyses were performed in comparison to the BCoV genome. In the region between the spike and membrane protein genes, a 290-nucleotide deletion is present, corresponding to the absence of BCoV ORFs ns4.9 and ns4.8. Nucleotide and amino acid similarity percentages were determined for the major HCoV-OC43 ORFs and for those of other group 2 coronaviruses. The highest degree of similarity is demonstrated between HCoV-OC43 and BCoV in all ORFs with the exception of the E gene. Molecular clock analysis of the spike gene sequences of BCoV and HCoV-OC43 suggests a relatively recent zoonotic transmission event and dates their most recent common ancestor to around 1890. An evolutionary rate in the order of 4 × 10−4 nucleotide changes per site per year was estimated. This is the first animal-human zoonotic pair of coronaviruses that can be analyzed in order to gain insights into the processes of adaptation of a nonhuman coronavirus to a human host, which is important for understanding the interspecies transmission events that led to the origin of the severe acute respiratory syndrome outbreak.

Coronaviruses are large (120- to 160-nm), roughly spherical particles with a linear, nonsegmented, capped, and polyadenylated positive-sense single-stranded RNA genome that is encapsidated in a helical nucleocapsid. The envelope is derived from intracellular membranes and contains a characteristic crown of widely spaced club-shaped spikes that are 12 to 24 nm long. The genus Coronavirus (International Committee on the Taxonomy of Viruses database [ICTVdb], virus code 03.019.0.1) belongs to the family Coronaviridae in the order Nidovirales (7, 8).

Before the 2002-to-2003 severe acute respiratory syndrome (SARS) epidemic, coronaviruses were somewhat neglected in human medicine, but they have always been of considerable importance in animal health. Coronaviruses infect a variety of livestock, poultry, and companion animals, in whom they can cause serious and often fatal respiratory, enteric, cardiovascular, and neurologic diseases (25). Most of our understanding about the molecular pathogenic properties of coronaviruses has been achieved by the veterinary virology community.

Dec 8, 2020

DUNE publishes first physics results from prototype detector

Posted by in category: particle physics

The DUNE collaboration has published their first scientific paper based on data collected with the ProtoDUNE single-phase detector located at CERN’s Neutrino Platform. The results show that the detector is performing with greater than 99% efficiency, making it not only the largest, but also the best-performing liquid-argon time projection chamber to date. Scientists now are using their findings to refine their experimental techniques and prepare for the construction of the international Deep Underground Neutrino Experiment at the Long-Baseline Neutrino Facility, a next-generation neutrino experimental program hosted by the Department of Energy’s Fermilab in the United States.

“These first results are great news for us,” said DUNE co-spokesperson Stefan Söldner-Rembold, professor at the University of Manchester in the UK. “They show that the ProtoDUNE-SP detector works even better than anticipated. Now we are ready for the construction of the first components for the DUNE detector, which will feature detector modules based on this prototype, but 20 times larger.”

DUNE is an ambitious international experiment that will measure the properties of tiny fundamental particles called neutrinos. Neutrinos are the most abundant matter particle in the universe, but because they rarely interact with other particles, they are incredibly difficult to study. There are at least three different types of neutrinos, and, every second, 65 billion of them pass through each square centimeter of Earth. As they travel, they do something peculiar: They change from one type to another. Scientists think that these neutrino oscillations — as well as oscillations involving antimatter neutrinos — could help answer some of the big questions in physics, such as the observed matter-antimatter asymmetry in the universe. DUNE will also look for neutrinos from supernovae and search for rare subatomic processes such as proton decay.

Dec 7, 2020

MIT’s ABRACADABRA Instrument: Pulling the Secrets of Dark Matter Out of a Hat

Posted by in categories: cosmology, particle physics

MIT grad student Chiara Salemi and Professor Lindley Winslow use the ABRACADABRA instrument to reveal insights into dark matter.

On the first floor of MIT’s Laboratory for Nuclear Science hangs an instrument called “A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus,” or ABRACADABRA for short. As the name states, ABRACADABRA’s goal is to detect axions, a hypothetical particle that may be the primary constituent of dark matter, the unseen and as-of-yet unexplained material that makes up the bulk of the universe.

Dec 7, 2020

Our Galaxy’s Brightest Gamma-Ray Binary System May Be Powered by a Magnetar Star

Posted by in categories: particle physics, space

A team of researchers led by members of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) has analyzed previously collected data to infer the true nature of a compact object—found to be a rotating magnetar, a type of neutron star with an extremely strong magnetic field—orbiting within LS 5039, the brightest gamma-ray binary system in the Galaxy.

Including former graduate student Hiroki Yoneda, Senior Scientist Kazuo Makishima and Principal Investigator Tadayuki Takahashi at the Kavli IMPU, the team also suggest that the particle acceleration process known to occur within LS 5039 is caused by interactions between the dense stellar winds of its primary massive star, and ultra-strong magnetic fields of the rotating magnetar.

Gamma-ray binaries are a system of massive, high-energy stars and compact stars. They were discovered only recently, in 2004, when observations of very-high-energy gamma-rays in the teraelectronvolt (TeV) band from large enough regions of the sky became possible. When viewed with visible light, gamma-ray binaries appear as bright bluish-white stars, and are indistinguishable from any other binary system hosting a massive star. However, when observed with X-rays and gamma-rays, their properties are dramatically different from those of other binaries. In these energy bands, ordinary binary systems are completely invisible, but gamma-ray binaries produce intense non-thermal emission, and their intensity appears to increase and decrease according to their orbital periods of several days to several years.

Dec 5, 2020

Massive Underground “Ghost Particle” Detector Finds Final Secret of Our Sun’s Fusion Cycle

Posted by in category: particle physics

A hyper-sensitive instrument, deep underground in Italy, has finally succeeded at the nearly impossible task of detecting CNO neutrinos (tiny particles pointing to the presence of carbon, nitrogen, and oxygen) from our sun’s core. These little-known particles reveal the last missing detail of the fusion cycle powering our sun and other stars.

In results published on November 26, 2020, in the journal Nature (and featured on the cover), investigators of the Borexino collaboration report the first detections of this rare type of neutrinos, called “ghost particles” because they pass through most matter without leaving a trace.

The neutrinos were detected by the Borexino detector, an enormous underground experiment in central Italy. The multinational project is supported in the United States by the National Science Foundation under a shared grant overseen by Frank Calaprice, professor of physics emeritus at Princeton; Andrea Pocar, a 2003 graduate alumna of Princeton and professor of physics at the University of Massachusetts-Amherst; and Bruce Vogelaar, professor of physics at the Virginia Polytechnical Institute and State University (Virginia Tech).

Dec 5, 2020

Researchers observe what could be the first hints of dark bosons

Posted by in categories: cosmology, particle physics

Extremely light and weakly interacting particles may play a crucial role in cosmology and in the ongoing search for dark matter. Unfortunately, however, these particles have so far proved very difficult to detect using existing high-energy colliders. Researchers worldwide have thus been trying to develop alternative technologies and methods that could enable the detection of these particles.

Over the past few years, collaborations between particle and atomic physicists working at different institutes worldwide have led to the development of a new technique that could be used to detect interactions between very light bosons and neutrons or electrons. Light bosons, in fact, should change the energy levels of electrons in atoms and ions, a change that could be detectable using the technique proposed by these teams of researchers.

Using this method, two different research groups (one at Aarhus University in Denmark and the other at Massachusetts Institute of Technology) recently performed experiments aimed at gathering hints of the existence of dark bosons, elusive particles that are among the most promising dark matter candidates or mediators to a dark sector. Their findings, published in Physical Review Letters, could have important implications for future dark matter experiments.

Dec 3, 2020

Magnetism Does the Twist: Skyrmions 10,000 Times Thinner Than a Human Hair Could Advance High-Density Data Storage

Posted by in categories: climatology, computing, particle physics, quantum physics

Scientists discovered a strategy for layering dissimilar crystals with atomic precision to control the size of resulting magnetic quasi-particles called skyrmions. This approach could advance high-density data storage and quantum magnets for quantum information science.

In typical ferromagnets, magnetic spins align up or down. Yet in skyrmions, they twist and swirl, forming unique shapes like petite porcupines or tiny tornadoes.

The tiny intertwined magnetic structures could innovate high-density data storage, for which size does matter and must be small. The Oak Ridge National Laboratory-led project produced skyrmions as small as 10 nanometers – 10,000 times thinner than a human hair.

Dec 3, 2020

Research leads to better modeling of hypersonic flow

Posted by in categories: engineering, military, particle physics

Hypersonic flight is conventionally referred to as the ability to fly at speeds significantly faster than the speed of sound and presents an extraordinary set of technical challenges. As an example, when a space capsule re-enters Earth’s atmosphere, it reaches hypersonic speeds—more than five times the speed of sound—and generates temperatures over 4,000 degrees Fahrenheit on its exterior surface. Designing a thermal protection system to keep astronauts and cargo safe requires an understanding at the molecular level of the complicated physics going on in the gas that flows around the vehicle.

Recent research at the University of Illinois Urbana-Champaign added new knowledge about the physical phenomena that occur as atoms vibrate, rotate, and collide in this extreme environment.

“Due to the relative velocity of the flow surrounding the vehicle, a shock is formed in front of the capsule. When the gas molecules cross the shock, some of their properties change almost instantaneously. Instead, others don’t have enough time to adjust to the abrupt changes, and they don’t reach their equilibrium values before arriving at the surface of the vehicle. The layer between the shock and heat shield is then found in nonequilibrium. There is a lot that we don’t understand yet about the reactions that happen in this type of flow,” said Simone Venturi. He is a graduate student studying with Marco Panesi in the Department of Aerospace Engineering at UIUC.

Dec 2, 2020

Why the Future of Nuclear Power Is Tiny and Factory-Made

Posted by in categories: nuclear energy, particle physics

In the 1950s, few things seemed more futuristic and utopian than harnessing nuclear energy to power your home. Towering nuclear reactors popped up across the U.S. with the promise of harvesting energy from smashed atoms of Uranium to power everything from lights in an office to an oven cooking a pot roast. With clean and efficient nuclear power, anything seemed possible.

But as the years went on, doubt about the safety of these reactors began to poison the bright future they’d once promised. Stories of nuclear waste polluting waterways downstream of power plants began to stir alarm, and in the 1980s the Chernobyl nuclear power plant explosion sent radiation billowing across Europe and into the tissues of an estimated 4,000 Ukrainians who died from radiation poisoning. Even as recently as 2011, Japan’s Fukushima nuclear power plant faced catastrophe when a tsunami knocked out its power supply and led all three of its nuclear reactors to melt down.

All in all, it’s been a tough few decades for nuclear energy’s public image. But nuclear scientists say that now, more than ever, is the time to reinvest in nuclear innovation. Governments agree: In the U.K. Rolls-Royce plans to roll out 16 mini-nuclear plants over the next five years and China, an emerging nuclear super power, has pledged to ramp up its nuclear use to meet emissions goals.

Dec 2, 2020

Heavy boson triplets test Standard Model

Posted by in category: particle physics

A recent observation of an extremely rare subatomic process allows scientists to test the Standard Model’s boundaries.