Calculation Shows Why Heavy Quarks Get Caught up in the Flow

Nuclear Theory Group Leader Peter Petreczky at the STAR detector of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory
Photo Credit: Courtesy of Brookhaven National Laboratory

New results will help physicists interpret experimental data from particle collisions at RHIC and the LHC and better understand the interactions of quarks and gluons

Using some of the world’s most powerful supercomputers, a group of theorists has produced a major advance in the field of nuclear physics—a calculation of the “heavy quark diffusion coefficient.” This number describes how quickly a melted soup of quarks and gluons—the building blocks of protons and neutrons, which are set free in collisions of nuclei at powerful particle colliders—transfers its momentum to heavy quarks.

The answer, it turns out, is very fast. As described in a paper just published in Physical Review Letters, the momentum transfer from the “freed up” quarks and gluons to the heavier quarks occurs at the limit of what quantum mechanics will allow. These quarks and gluons have so many short-range, strong interactions with the heavier quarks that they pull the “boulder”-like particles along with their flow.

The work was led by Peter Petreczky and Swagato Mukherjee of the nuclear theory group at the U.S. Department of Energy’s Brookhaven National Laboratory, and included theorists from the Bielefeld, Regensburg, and Darmstadt Universities in Germany, and the University of Stavanger in Norway.

The calculation will help explain experimental results showing heavy quarks getting caught up in the flow of matter generated in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at Europe’s CERN laboratory. The new analysis also adds corroborating evidence that this matter, known as a “quark-gluon plasma” (QGP), is a nearly perfect liquid, with a viscosity so low that it also approaches the quantum limit.

Romantic Love in Humans May Have Evolved From Same-Sex Friendship

Two adolescent male chimpanzees, Barron, 15, and PeeWee, 9, grooming.
Photo Credit: Aaron Sandel.

Romantic heterosexual relationships in humans may have evolved from same-sex pairings in a common ancestor of humans and chimpanzees, according to a novel hypothesis by a researcher at The University of Texas at Austin.

The prevailing explanation of heterosexual pair bonding and romantic love in humans is that it evolved from the mother-infant bond present in many mammals. In a paper published in the journal Evolutionary Anthropology, anthropology professor Aaron Sandel cites primate research — including his own decadelong studies of chimpanzees in Kibale National Park, Uganda — to propose instead that this behavior evolved in humans from same-sex pair bonding already present in a common ancestor of humans and chimpanzees.

A pair bond is a cooperative relationship between nonrelated adults that remains stable over time and includes an emotional connection, rather than being merely transactional. Chimpanzees, humans’ closest relative, do not pair bond with their mates, but adult males of the species form same-sex bonds lasting as long as 13 years.

Scientists analyze a single atom with X-rays for the first time

Left: Image of a ring-shaped molecular host that contains just one iron atom. Right: X-ray absorption spectrum of single atom detected at location B in the molecular ring. Spectrum matches that of iron.
 Image Credit: Argonne National Laboratory

In the most powerful X-ray facilities in the world, scientists can analyze samples so small they contain only 10,000 atoms. Smaller sizes have proved exceedingly difficult to achieve, but a multi-institutional team has scaled down to a single atom.

“X-ray beams are used everywhere, including security scanning, medical imaging and basic research,” said Saw Wai Hla, physicist in the U.S. Department of Energy’s (DOE) Argonne National Laboratory and professor at Ohio University. ​“But since the discovery of X-rays in 1895, scientists have not been able to detect and analyze just one atom. It has been a dream of scientists to be able to do so for decades. Now we can.”

As just announced in Nature, scientists from Argonne and several universities report being able to characterize the elemental type and chemical properties of just one atom by using X-ray beams. This new capability will impact fundamental research in numerous scientific disciplines and the development of new technologies.

Exposure to “forever chemicals” during pregnancy linked to increased risk of obesity in kids

Toxic "forever chemicals" are used in oil- and water-repellant textiles, personal care products, firefighting foams, food packaging, medical products and many other household products.
Photo Credit: Stijn Dijkstra

A federally funded study led by researchers at Brown University showed links between prenatal exposure to per- and polyfluoroalkyl substances and slightly higher body mass indices in children.

The risks of exposure to “forever chemicals” start even before birth, a new study confirms, potentially setting up children for future health issues.

Exposure to per- and polyfluoroalkyl substances (PFAS) during pregnancy was linked to slightly higher body mass indices and an increased risk of obesity in children, according to a new Environmental Health Perspectives study led by Brown University researchers.

While this link has been suggested in previous research, the data has been inconclusive. The new study, which was funded by the Environmental Influences on Child Health Outcomes program at the National Institutes of Health, involves a much broader data set with research sites across the country, said lead author Yun “Jamie” Liu, a postdoctoral research associate in epidemiology at the Brown University School of Public Health.

“The findings were based on eight research cohorts located in different parts of the U.S. as well as with different demographics,” Liu said. “This makes our study findings more generalizable to the population as a whole.”

When it comes to bumblebees, does size matter?

Why bumblebee body sizes vary so significantly is a mystery of bumble biology.
Photo Credit: Myriams-Fotos

While honeybee workers are all the same size, that’s not true for bumblebees. Scientists aren’t sure what’s behind the wide variety in bumble body sizes, but a new UC Riverside project aims to find out.

Certain crops, like greenhouse tomatoes, eggplant, peppers, and blueberries, rely on bumblebees for a style of pollination that only bumblebees can perform. Among growers, the preference can be for bigger-bodied bumblebees because they’re thought to be more efficient pollinators. 

Enabled by a $750,000 grant from the National Institute of Food and Agriculture, the research team will investigate factors suspected of influencing bumblebee biology and body size, including climate change, wildfires, and the presence of nearby honeybee colonies.

Link between cardiovascular health & disorders such as carpal tunnel

From left to right: Richard Kendall, MD, Matthew Thiese, PhD, Eric Wood, MD, Kurt Hegmann, MD, from the Rocky Mountain Center for Environmental Health.
Photo Credit: Charlie Ehlert

People with higher risks of cardiovascular disease are significantly more likely to develop carpal tunnel syndrome, tennis elbow, golfer’s elbow, and rotator cuff tendinitis, according to a new study involving researchers at the University of Utah and the Rocky Mountain Center for Occupational and Environmental Health.

The findings of the study, published in the Journal of Occupational and Environmental Medicine, have implications for the prevention and treatment of these common musculoskeletal disorders, which affect tens of millions of Americans each year and result in annual costs of more than $6 billion.

The lead author of the study is Kurt Hegmann, M.D., a University of Utah professor and the director of the Rocky Mountain Center for Occupational and Environmental Health, a partnership between the University of Utah and Weber State University. He said the strength of the associations the researchers discovered between cardiovascular disease risk factors and musculoskeletal disorders is staggering.

“It’s rare that you see 17-fold risks of diseases,” Hegmann said. “These results tell us that prioritizing cardiovascular health is a key to preventing these musculoskeletal disorders, which can have a debilitating impact on people’s quality of life. This is something we and other researchers and medical professionals need to be paying a lot of attention to.”

Nanomaterials: glass printed sintered-free in 3D

The new process can be used to create a wide variety of quartz glass structures on a nanometer scale.
Full Size Image
 Image Credit: Dr. Jens Bauer, KIT

Process developed at KIT manages with relatively low temperatures and enables high resolutions for applications in optics and semiconductor technology - publication in science

Nanometer-fine structures made of quartz glass, which can be printed directly on semiconductor chips, are produced by a process developed at the Karlsruhe Institute of Technology (KIT). A hybrid organic-inorganic polymer resin serves as the starting material for the 3D printing of silicon dioxide. Since the process does not require sintering, the temperatures required for this are significantly lower. At the same time, a higher resolution enables nanophotonics with visible light. The research team reports in the journal Science.

Printing quartz glass consisting of pure silicon dioxide in micro and nanometer-fine structures opens up new possibilities for many applications in optics, photonics and semiconductor technology. So far, however, techniques based on traditional sintering have dominated. The temperatures required for sintering silicon dioxide nanoparticles are above 1,100 degrees Celsius - far too hot for direct separation on semiconductor chips. A research team led by Dr. Jens Bauer from the KIT's Institute for Nanotechnology (INT) has now developed a new process for producing transparent quartz glass with high resolution and excellent mechanical properties at significantly lower temperatures.

Using genomics to unlock the full potential of industrial hemp

Alex Harkess, PhD
Photo Credit: Courtesy of HudsonAlpha Institute for Biotechnology

Plant biologist Alex Harkess, PhD, and his lab at HudsonAlpha Institute for Biotechnology are on a mission to change the future of food and fiber crops, one flowering plant species at a time. Much of plant breeding and global food production relies on the pollination of flowers to produce fruits that are eaten and used to produce further progeny. This process might sound straightforward, but it is complicated because some flowers contain only male or female reproductive organs, others contain both (hermaphrodites), and some can even switch sexes. 

How flowers become male, female, or hermaphroditic is a complex phenomenon. Although not completely understood, it is imperative for crop breeding programs looking to create food and fiber crops better adapted to changing environmental pressures. This is especially true in crop species where one plant sex is more valuable than the other, like female hops that produce cones used in the beer industry, male asparagus plants that live longer in fields, and hermaphroditic papaya fruits that taste better than female fruits. 

While the exact mechanism of sex determination is a mystery in many species, it is widely accepted that genetics plays a major role. Dr. Harkess and the members of his lab are experts at using genomics to understand plant reproduction and the genes that control sex in flowers. Sex-determination genes have only been concretely defined in five plant species, with Harkess playing a critical role in their identification in asparagus.  

Prognosis of nasopharyngeal carcinoma

Illustration Credit: Sisi Huang and Yun Du

Nasopharyngeal carcinoma (NPC) is a type of cancer that occurs in the nasopharynx, which is located behind the nose and above the back of the throat. NPC has a geographically skewed distribution worldwide, with high incidence rates in East and Southeast Asia. NPC is difficult to detect early, and treatment usually involves radiation therapy, chemotherapy or a combination of the two.

Recent hospital-based studies suggest that the development of new radiotherapy techniques has contributed to improved NPC prognosis, but little population-based research on NPC patient survival is available. Similarly, little is known about potential environmental prognostic factors for NPC, such as body mass index (BMI) and body shape, pretreatment plasma Epstein-Barr virus (EBV) DNA, and oral microbiome. Therefore, PhD student Yun Du at the Department of Medical Epidemiology and Biostatistics aimed her thesis to characterize population-based NPC survival patterns and identify potential prognostic factors for NPC in southern China.

Neurotic people are more likely to suffer from mood swings

Neurotic people experience negative emotions more intensely and have more mood swings than others.
Photo Credit: Gerd Altmann

In everyday life, our emotions often change from moment to moment, and people experience these fluctuations to varying degrees. Psychologists at Leipzig University have studied the relationship between the personality trait neuroticism – a potential risk factor for mental health – and emotional experiences. They found that neurotic people experience negative emotions not only more intensely, but also with more mood swings than others. They have just published their findings in the Proceedings of the National Academy of Sciences (PNAS).

“Previous studies are in agreement that neurotic people experience stronger negative emotions in everyday life. Because of new, contradictory studies, there has been disagreement about whether this is also associated with increased variability in emotional experiences, i.e. mood swings,” says the study’s first author, Nina Mader from the Wilhelm Wundt Institute of Psychology at Leipzig University. Personality psychologists at Leipzig University have developed a new approach to modelling data that solves previous methodological problems. “We use an approach from Bayesian statistics that allows additional flexibility in data modelling. We first successfully tested this approach in simulations and then re-examined 13 longitudinal data sets. The results suggest that neurotic people do indeed experience greater variability in negative emotions,” explains Mader. A total of 2,518 people were asked about their emotions.