What Are The Effects Of Temperature On Magnetic White Dwarfs? (Planetary Science)

Veronica Dexheimer and colleagues in their recent paper, studied the microscopic and macroscopic properties of white dwarfs. They model the interior of white dwarfs as a nuclei lattice surrounded by a relativistic free Fermi gas of electrons, accounting for effects from temperature and magnetic field. They found that, at low densities, both temperature and magnetic field effects play an important role in the calculation of microscopic thermodynamical quantities. Their study recently appeared in Arxiv.

Several studies modeled the core of white dwarf stars with one of the assumptions that the temperature or magnetic field can be disregarded. But, some recent observations suggested that a few white dwarfs may require the inclusion of both temperature and magnetic field effects in the calculation of the matter equation of state. In that light, Veronica Dexheimer and colleagues now examined for the first time, the effects of including both temperature and magnetic field into the equation of state of white dwarfs.

“To our knowledge, this is the first time that simultaneous effects of including both temperature and magnetic field in the equation of state for white dwarfs was investigated.”

— Veronica Dexheimer, one of the author of the study

Focusing first on microscopic quantities, they found that high temperatures tend to overpower the effects of magnetic fields which are expected to be seen in white dwarfs. While at lower temperatures, the magnetic field effects are more pronounced with very visible Van Alphen oscillations.

(Article continues below images)

FIG. 1. Left: (Color online) Magnetic field profile inside the most massive star of a sequence produced with current constant f0 = 10-³ in the polar direction as a function of energy density. Right: (Color online) The same as left panel but in the equatorial direction. © Dexheimer et al.
Fig 2: (Color online) Mass-radius diagram for sequences of stars produced within several temperature scenarios. Lines marked with an asterisk denote sequences with magnetic field effects generated by fixing a current constant f0 = 10-³ © Dexheimer et al.

Later, they numerically solved the Einstein Maxwell equations, in order to obtain results for macroscopic stellar properties, such as mass and radius, in the case of magnetic stars. They found that the strong magnetic fields they considered were not large enough to change properties such as stellar masses and radii, although a finite temperature magnetic field profile in different directions of the star was extracted.

“In the future, we intend on using these profiles to evaluate realistic magnetic field effects in, for example, pycnonuclear fusion reactions, and possibly on the crystalline structure of white dwarfs.

— concluded authors of the study

For more, refer:

J. Peterson, V. Dexheimer, R. Negreiros, B. G. Castanheira, “Effects of Magnetic Fields in Hot White Dwarfs”, Arxiv, pp. 1-10, 2021. https://arxiv.org/abs/2105.03387

Note for editors of other websites: To reuse this article fully or partially, kindly give credit either to our author S. Aman or provide a link of our article

Intense Light May Hold Answer to Dilemma Over Heart Treatment (Medicine)

Blocking a gene could aid cardiac health but prove lethal, light may be the key

WHAT YOU NEED TO KNOW: Scientists have discovered that blocking a specific gene could help cardiac health but it can also be fatal. New research now shows intense light may be a way around this dilemma.

Looking to safely block a gene linked to factors known to cause heart disease, scientists at the University of Colorado Anschutz Medical Campus may have found a new tool – light.

The discovery, reported today in the journal Trends in Molecular Medicine, may solve a medical dilemma that has baffled scientists for years.

The gene, ANGPTL4, regulates fatty lipids in plasma. Scientists have found that people with lower levels of it also have reduced triglycerides and lipids, meaning less risk for cardiovascular disease.

But blocking the gene using antibodies triggered dangerous inflammation in mice. Complicating things further, the gene can be beneficial in reducing the risk of myocardial ischemia and helping to repair a damaged heart.

“The scientific community is still trying to figure out a way to safely inhibit it,” said the study’s lead author Tobias Eckle, MD, PhD, professor of anesthesiology at the University of Colorado School of Medicine. “Now we have discovered that ANGPTL4 is a gene with a circadian pattern. It can be influenced by light.”

Eckle previously discovered that light therapy can protect the heart. In this study, his team did an unbiased, whole genome array, profiling intense, light-dependent cardiac gene expressions. They found that ANGPTL4 was the top light dependent gene. 

Eckle believes the gene could be manipulated by light without risking the lethal effects of blocking it entirely. 

“We demonstrate that if you want to get around this problem you don’t knock out the protein, you enhance the circadian amplitude by increasing its troughs and peaks,” he said. “Throughout the day, you will have times of enhanced protein expression and times with lower expression.” 

Eckle said the gene can be activated by light therapy, a flavonoid known as nobiletin or through drug formulations. 

“In fact, circadian amplitude enhancement of ANGPTL4 would be quite distinct from disabling or even overexpressing it,” Eckle said. “ Enhancing peaks and troughs would mean that at specific times of day, the ANGPTL4 response would be enhanced and 12 hours later the response would be even more robustly suppressed.” 

The discovery, Eckle said, reinforces the physiological importance of circadian rhythms as well as the light and oxygen pathways threading through the human body. 

“Sunlight and oxygen are the most life-sustaining things on this planet,” Eckle said. “We evolved to adapt to those two things and we have pathways throughout our body that sense them.”

He said that chronotherapy, giving medications at different times of the day to maximize benefits and minimize side-effects, is a new frontier in medicine. 

“The administration of any drug should be connected to a specific time of day,” he said. “I believe chronotherapy is the future of medicine.”

Provided by Anschutz

Bacteria Do Not Colonize the Gut Before Birth, Says Collaborative Study (Medicine)

It happens during and after birth

It is well known that each person’s gut bacteria is vital for digestion and overall health, but when does that gut microbiome start?

New research led by scientists from McMaster University and Charité – Universitätsmedizin Berlin in Germany has found it happens during and after birth, and not before.

McMaster researchers Deborah Sloboda and Katherine Kennedy examined prenatal stool (meconium) samples collected from 20 babies during breech Cesarean delivery.

“The key takeaway from our study is we are not colonized before birth. Rather, our relationship with our gut bacteria emerges after birth and during infancy,” said Kennedy, first author of the study and a PhD student, whose findings are published in Nature Microbiology.

Recent studies have sparked controversy by claiming that we are colonized by gut bacteria before birth. But, Kennedy said, studies such as these have been criticized for the ways they control for contamination.

“By including only breech caesarean deliveries in healthy pregnant women we were able to avoid the transmission of bacteria that occurs naturally during a vaginal birth,” said Thorsten Braun, co-senior author and lead obstetric consultant and deputy director of the Department of ‘Experimental Obstetrics’ at Charité – Universitätsmedizin Berlin.

Kennedy said recent data suggest that a person’s relationship with their own gut bacteria is most important in early life, during critical stages of immunological and physiological development.

Sloboda, co-senior author, agrees.

“The fact that colonization of infants’ guts occurs during and after their births, means that not only is it vulnerable to early environmental influences, but could also offers a window of potential intervention,” said Sloboda, professor of biochemistry and biomedical sciences at McMaster and the Canada Research Chair in perinatal programming.

“While many of the exact mechanisms surrounding gut bacteria and their role in our early development is unclear, discovering when and how we are colonized is a key first step.”

External funding for the study came from the Canadian Institutes of Health Research.

Featured image: First author and PhD student Katherine Kennedy (left) and PhD student Patrycja Jazwiec © McMaster University

Reference: Kennedy, K.M., Gerlach, M.J., Adam, T. et al. Fetal meconium does not have a detectable microbiota before birth. Nat Microbiol (2021). https://doi.org/10.1038/s41564-021-00904-0

Provided by McMaster University

Should We Panic Over Declining Sperm Counts? Harvard Researchers Say Not So Fast (Medicine)

An alternative explanation of recent findings of declining sperm counts: normal, non-pathological variation

A new study from the Harvard GenderSci Lab in the journal Human Fertility, “The Future of Sperm: A Biovariability Framework for Understanding Global Sperm Count Trends” questions the panic over apparent trends of declining human sperm count.

Recent studies have claimed that sperm counts among men globally, and especially from “Western” countries, are in decline, leading to apocalyptic claims about the possible extinction of the human species.

But the Harvard paper, by Marion Boulicault, Sarah S. Richardson, and colleagues, reanalyzes claims of precipitous human sperm declines, re-evaluating evidence presented in the widely-cited 2017 meta-analysis by Hagai Levine, Shanna Swan, and colleagues.

Richardson: “The extraordinary biological claims of the meta-analysis of sperm count trends and the public attention it continues to garner raised questions for the GenderSci Lab, which specializes in analyzing bias and hype in the sciences of sex, gender, and reproduction and in the intersectional study of race, gender, and science.”

Boulicault et al. propose an alternative explanation of sperm count trends in human populations: That sperm count varies within a wide range, much of which can be considered non-pathological and species-typical, and that above a critical threshold, more is not necessarily an indicator of better health or higher probability of fertility relative to less. The authors term this the Sperm Count Biovariability hypothesis.

The paper argues that a biovariability framework better supports critically important research on factors affecting the reproductive health of all men. Lead author Boulicault: “By proposing an alternative approach to sperm count data, we aim to contribute to the burgeoning discussion among reproductive health scientists and other researchers and clinicians about men’s health.”

Among the reasons to consider alternative interpretations of sperm count patterns than that of precipitous and fertility-threatening declines in men’s sperm counts is the life of such theories in Alt-Right, white supremacist, and men’s rights discourse. These groups have used Levine and Swan’s research to argue that the fertility and health of men in whiter nations are in imminent danger, often linking the danger to the perceived increase in ethnic and racial diversity and to the influence of feminist and anti-racist social movements.

The Harvard researchers argue that claims of recent and impending dramatic declines in human sperm counts are based on a number of scientifically and ethically problematic assumptions:

  • Claims about precipitous sperm decline assume that sperm counts in Anglophone developed nations of the 1970s constitute the species optimum.
  • Declining sperm counts do not predict declining fertility. The assumption that male fertility scales proportionately with sperm count is unsupported by any available evidence.
  • The proposed causal mechanism for lower sperm counts of exposure to environmental endocrine disrupting chemicals is not supported by the geographical and historical patterns of average population sperm counts.
  • The use of two categories labeled “Western” and “Other” in analyzing sperm counts, as seen in the major 2017 meta-analysis of sperm decline studies, is scientifically unsound and embeds unethical racist and colonial assumptions in the study design. These statistical aggregations obscure the diversity across rural and urban locations within nations, and disguise the fact that there is very limited data on individuals’ sperm counts in countries Levine et al. categorized as “Other.”

As the paper concludes, “Researchers must take care to weigh hypotheses against alternatives and consider the language and narrative frames in which they present their work. In addition to its explanatory virtues, we argue that biovariability offers a more promising framework than does “sperm decline” for attending to these imperatives.”

Featured image: A new study from the Harvard GenderSci Lab in the journal Human Fertility, “The Future of Sperm: A Biovariability Framework for Understanding Global Sperm Count Trends” questions the panic over apparent trends of declining human sperm count. © Harvard GenderSci Lab

Reference: Marion Boulicault, Meg Perret, Jonathan Galka, Alex Borsa, Annika Gompers, Meredith Reiches & Sarah Richardson (2021) The future of sperm: a biovariability framework for understanding global sperm count trends, Human Fertility, DOI: 10.1080/14647273.2021.1917778

Provided by Harvard University

New Tools Enable Rapid Analysis of Coronavirus Sequences and Tracking of Variants (Medicine)

UShER allows researchers to quickly see how a new viral sequence is related to all other variants of SARS-CoV-2, crucial information for tracking transmission dynamics

The COVID-19 pandemic has spurred genomic surveillance of viruses on an unprecedented scale, as scientists around the world use genome sequencing to track the spread of new variants of the SARS-CoV-2 virus. The rapid accumulation of viral genome sequences presents new opportunities for tracing global and local transmission dynamics, but analyzing so much genomic data is challenging.

“There are now more than a million genome sequences for SARS-CoV-2. No one had anticipated that number when we started sequencing this virus,” said Russ Corbett-Detig, assistant professor of biomolecular engineering at UC Santa Cruz.

The sheer number of coronavirus genome sequences and their rapid accumulation makes it hard to place new sequences on a “family tree” showing how they are all related. But Corbett-Detig’s group at the UC Santa Cruz Genomics Institute has developed a new method that does this with unprecedented speed. Called Ultrafast Sample Placement on Existing Trees (UShER), this powerful tool is described in a paper published May 10 in Nature Genetics.

UShER identifies the relationships between a user’s newly sequenced viral genomes and all known SARS-CoV-2 virus genomes by adding them to an existing phylogenetic tree, a branching diagram like a family tree that shows how the virus has evolved in different lineages as it accumulates mutations.

“We are able to maintain a comprehensive phylogenetic tree of more than 1.2 million coronavirus sequences and update it with new sequences in real time. No other tool can handle trees of this size with a comparable efficiency,” said first author Yatish Turakhia, a postdoctoral scholar at the Genomics Institute. “This helps us keep track of all variants in circulation, including new variants that are emerging.”

This kind of sequence analysis can be used to discover new strains of the virus as they emerge and track their evolution and transmission dynamics. It can also be used to identify links between individual cases of coronavirus infection and to trace chains of transmission, an approach known as genomic contact tracing.

“The challenge is to get results soon enough to make meaningful predictions that public health agencies can use to try to control an outbreak,” said Corbett-Detig, a corresponding author of the paper. “Our method is orders of magnitude faster than anything else out there, placing new samples in tenths of a second.”

UShER and related data visualization tools are available to the research community through the UCSC SARS-CoV-2 Genome Browser, which also provides access to a wide range of data and results from ongoing scientific research on the virus, including new variants that are especially concerning.

“Our browser is the most comprehensive information resource for mutations appearing in the virus and what they mean for our battle against it,” said coauthor David Haussler, professor of biomolecular engineering and director of the Genomics Institute. “Thanks to Russ’s team, it includes the world’s most comprehensive phylogenetic tree of the different lineages of the virus, and that tree continues to grow every week, as fast as new data appear.”

Like all viruses, SARS-CoV-2 acquires mutations as it replicates and spreads. Most of these random variations in the genome sequence have no effect on the behavior of the virus, but researchers can still use them to identify different variants or strains of the virus, see how they are related, and determine if two samples are part of the same transmission chain.

Scientists have identified several important mutations that appear to make the virus more infectious. Variants of SARS-CoV-2 with these mutations are spreading more rapidly than other variants. Coauthor Angie Hinrichs, a UCSC Genome Browser engineer, used UShER to determine that one of these variants, known as B.1.1.7, entered the United States through several independent introductions. It is now the dominant strain in the United States.

Turakhia said he has begun using UShER to study a new variant that has emerged in India and appears to be spreading rapidly there. Known as B.1.617, this lineage of the virus has two mutations of potential concern to scientists. “We don’t know yet how concerning it is, but it is important to track it,” he said.

Viral genomics can reveal transmission chains not found through conventional contact tracing, Corbett-Detig said. This approach can help identify superspreader events, where one person transmitted the virus to many others, and it can also show that two cases from the same location are actually unrelated infections, not part of the same transmission chain, because the viral sequences differ too much.

“It’s an approach that is likely to be valuable moving forward, so we’re building the tools to enable people to do this in real time,” he said. “If you want to know who transmitted the virus to whom, or where in the world a new sample may have come from, you need to take the samples from your community and project them onto the known phylogenetic tree of all the other SARS-CoV-2 genome sequences, and conventional phylogenetic methods just can’t do this in a reasonable amount of time.”

That’s because conventional methods have to recalculate the entire tree every time new sequences are added, which is much too time-consuming when there are hundreds of thousands of sequences. UShER places samples onto an existing global phylogeny almost instantly, and it provides a local subtree of the added samples and their nearest neighbors so that their relationships can be visualized and examined in detail.

The researchers showed that UShER finds the right placement in 97% of cases. In the other 3%, incorrect placements are very close to the true site and still useful for contact tracing. UShER can also be used for quality control to quickly identify and remove low-quality sequences that may contain sequencing errors. The UShER results can be visualized and explored on the Nextstrain platform for interactive visualization of phylogenetic trees and maps of how the virus is spreading.

A training module for UShER is included in the CDC COVID-19 Genomic Epidemiology Toolkit (Module 3.3, including a video, slides, and links to more resources).

In addition to Turakhia, Corbett-Detig, Hinrichs, and Haussler, the coauthors of the paper include Bryan Thornlow and Landen Gozashti at UC Santa Cruz, Nicola De Maio at the European Bioinformatics Institute, and Robert Lanfear at Australian National University, Canberra. This work was funded by the Alfred P. Sloan Foundation and the National Institutes of Health.

Featured image: In this example of UShER results, displayed using Nextstrain, sequences representing a hypothetical outbreak are yellow, previously sampled sequences are blue, and branches are labeled by nucleotide mutations. © UC Santa Cruz Genomics Institute

Reference: Turakhia, Y., Thornlow, B., Hinrichs, A.S. et al. Ultrafast Sample placement on Existing tRees (UShER) enables real-time phylogenetics for the SARS-CoV-2 pandemic. Nat Genet (2021). https://doi.org/10.1038/s41588-021-00862-7

Provided by University of California Santa Cruz

In The Emptiness Of Space, Voyager I Detects Plasma ‘Hum’ (Astronomy)

Voyager 1 – one of two sibling NASA spacecraft launched 44 years ago and now the most distant human-made object in space – still works and zooms toward infinity.

As the craft toils, it has long since zipped past the edge of the solar system through the heliopause – the solar system’s border with interstellar space – into the interstellar medium. Now, its instruments have detected the constant drone of interstellar gas (plasma waves), according to Cornell-led research published May 10 in Nature Astronomy.

Examining data slowly sent back from more than 14 billion miles away, Stella Koch Ocker, a Cornell doctoral student in astronomy, has uncovered the emission. “It’s very faint and monotone, because it is in a narrow frequency bandwidth,” Ocker said. “We’re detecting the faint, persistent hum of interstellar gas.”

This work allows scientists to understand how the interstellar medium interacts with the solar wind, Ocker said, and how the protective bubble of the solar system’s heliosphere is shaped and modified by the interstellar environment.

Launched in September 1977, the Voyager 1 spacecraft flew by Jupiter in 1979 and then Saturn in late 1980. Travelling at about 38,000 mph, Voyager 1 crossed the heliopause in August 2012.

After entering interstellar space, the spacecraft’s Plasma Wave System detected perturbations in the gas. But, in between those eruptions – caused by our own roiling sun – researchers have uncovered a steady, persistent signature produced by the tenuous near-vacuum of space.

”The interstellar medium is like a quiet or gentle rain,” said senior author James Cordes, the George Feldstein Professor of Astronomy (A&S). “In the case of a solar outburst, it’s like detecting a lightning burst in a thunderstorm and then it’s back to a gentle rain.”

Ocker believes there is more low-level activity in the interstellar gas than scientists had previously thought, which allows researchers to track the spatial distribution of plasma – that is, when it’s not being perturbed by solar flares.

Cornell research scientist Shami Chatterjee explained how continuous tracking of the density of interstellar space is important. “We’ve never had a chance to evaluate it. Now we know we don’t need a fortuitous event related to the sun to measure interstellar plasma,” Chatterjee said. “Regardless of what the sun is doing, Voyager is sending back detail. The craft is saying, ‘Here’s the density I’m swimming through right now. And here it is now. And here it is now. And here it is now.’ Voyager is quite distant and will be doing this continuously.”

Voyager 1 left Earth carrying a Golden Record created by a committee chaired by the late Cornell professor Carl Sagan, as well as mid-1970s technology.

“Scientifically, this research is quite a feat. It’s a testament to the amazing Voyager spacecraft,” Ocker said. “It’s the engineering gift to science that keeps on giving.”

In addition to Ocker, Cordes and Chatterjee, the paper, “Persistent plasma waves in interstellar space detected by Voyager 1,” was co-authored by professor emeritus Donald A. Gurnett, the principal investigator on the plasma wave system (PWS)) on both Voyager spacecraft; Steven R. Spangler, professor; and research scientist William S. Kurth, co-investigator on PWS, all from the University of Iowa.

NASA, the Jet Propulsion Laboratory and the National Science Foundation supported the work. Cordes, Chatterjee and Ockler are members of Cornell’s Carl Sagan Institute.

Featured image: In an artist’s depiction, the Voyager 1 craft continues to cruise through interstellar space. © NASA JPL

Reference: Ocker, S.K., Cordes, J.M., Chatterjee, S. et al. Persistent plasma waves in interstellar space detected by Voyager 1. Nat Astron (2021). https://doi.org/10.1038/s41550-021-01363-7

Provided by Cornell University

How Planets Form Controls Elements Essential for Life? (Planetary Science)

Rice scientists attribute Earth’s nitrogen to rapid growth of moon- to Mars-sized bodies

The prospects for life on a given planet depend not only on where it forms but also how, according to Rice University scientists.

Planets like Earth that orbit within a solar system’s Goldilocks zone, with conditions supporting liquid water and a rich atmosphere, are more likely to harbor life. As it turns out, how that planet came together also determines whether it captured and retained certain volatile elements and compounds, including nitrogen, carbon and water, that give rise to life.

In a study published in Nature Geoscience, Rice graduate student and lead author Damanveer Grewal and Professor Rajdeep Dasgupta show the competition between the time it takes for material to accrete into a protoplanet and the time the protoplanet takes to separate into its distinct layers — a metallic core, a shell of silicate mantle and an atmospheric envelope in a process called planetary differentiation — is critical in determining what volatile elements the rocky planet retains.

Using nitrogen as proxy for volatiles, the researchers showed most of the nitrogen escapes into the atmosphere of protoplanets during differentiation. This nitrogen is subsequently lost to space as the protoplanet either cools down or collides with other protoplanets or cosmic bodies during the next stage of its growth.

This process depletes nitrogen in the atmosphere and mantle of rocky planets, but if the metallic core retains enough, it could still be a significant source of nitrogen during the formation of Earth-like planets.

Rice University geochemists analyzed experimental samples of coexisting metals and silicates to learn how they would chemically interact when placed under pressures and temperatures similar to those experienced by differentiating protoplanets. Using nitrogen as a proxy, they theorize that how a planet comes together has implications for whether it captures and retains volatile elements essential to life. © Tommy LaVergne/Rice University

Dasgupta’s high-pressure lab at Rice captured protoplanetary differentiation in action to show the affinity of nitrogen toward metallic cores.

“We simulated high pressure-temperature conditions by subjecting a mixture of nitrogen-bearing metal and silicate powders to nearly 30,000 times the atmospheric pressure and heating them beyond their melting points,” Grewal said. “Small metallic blobs embedded in the silicate glasses of the recovered samples were the respective analogs of protoplanetary cores and mantles.”

Using this experimental data, the researchers modeled the thermodynamic relationships to show how nitrogen distributes between the atmosphere, molten silicate and core.

“We realized that fractionation of nitrogen between all these reservoirs is very sensitive to the size of the body,” Grewal said. “Using this idea, we could calculate how nitrogen would have separated between different reservoirs of protoplanetary bodies through time to finally build a habitable planet like Earth.”

Their theory suggests that feedstock materials for Earth grew quickly to around moon- and Mars-sized planetary embryos before they completed the process of differentiating into the familiar metal-silicate-gas vapor arrangement.

Rice University graduate student Damanveer Grewal, left, and geochemist Rajdeep Dasgupta discuss their experiments in the lab, where they compress complex mixtures of elements to simulate conditions deep in protoplanets and planets. In a new study, they determined that how a planet comes together has implications for whether it captures and retains the volatile elements, including nitrogen, carbon and water, essential to life. © Tommy LaVergne/Rice University

In general, they estimate the embryos formed within 1-2 million years of the beginning of the solar system, far sooner than the time it took for them to completely differentiate. If the rate of differentiation was faster than the rate of accretion for these embryos, the rocky planets forming from them could not have accreted enough nitrogen, and likely other volatiles, critical to developing conditions that support life.

“Our calculations show that forming an Earth-size planet via planetary embryos that grew extremely quickly before undergoing metal-silicate differentiation sets a unique pathway to satisfy Earth’s nitrogen budget,” said Dasgupta, the principal investigator of CLEVER Planets, a NASA-funded collaborative project exploring how life-essential elements might have come together on rocky planets in our solar system or on distant, rocky exoplanets.

“This work shows there’s much greater affinity of nitrogen toward core-forming metallic liquid than previously thought,” he said.

The study follows earlier works, one showing how the impact by a moon-forming body could have given Earth much of its volatile content, and another suggesting that the planet gained more of its nitrogen from local sources in the solar system than once believed.

In the latter study, Grewal said, “We showed that protoplanets growing in both inner and outer regions of the solar system accreted nitrogen, and Earth sourced its nitrogen by accreting protoplanets from both of these regions. However, it was unknown as to how the nitrogen budget of Earth was established.”

“We are making a big claim that will go beyond just the topic of the origin of volatile elements and nitrogen, and will impact a cross-section of the scientific community interested in planet formation and growth,” Dasgupta said.

Featured image: Nitrogen-bearing, Earth-like planets can be formed if their feedstock material grows quickly to around moon- and Mars-sized planetary embryos before separating into core-mantle-crust-atmosphere, according to Rice University scientists. If metal-silicate differentiation is faster than the growth of planetary embryo-sized bodies, then solid reservoirs fail to retain much nitrogen and planets growing from such feedstock become extremely nitrogen-poor. © Illustration by Amrita P. Vyas/Rice University

Reference: Grewal, D.S., Dasgupta, R., Hough, T. et al. Rates of protoplanetary accretion and differentiation set nitrogen budget of rocky planets. Nat. Geosci. (2021). https://doi.org/10.1038/s41561-021-00733-0

Provided by Rice University

Active Cavity Solitons: A New Avenue for Measuring Light Waves (Physics)

A scientific team highlights the existence of new ultra-stable, high-power cavity solitons. This new type of pulse, hybrid and universal could allow major advances in many areas such as high precision clocks.

Unlike the oscillations of sound waves, the oscillations of light are so rapid that extremely complex equipment is required to be able to observe them directly. It is however possible indirectly to measure precisely the frequencies of these oscillations thanks to the frequency combs. These combs are composed of a set of regularly spaced “teeth” where each tooth corresponds to a frequency. Used as real graduated rulers, they offer the possibility of measuring an optical frequency with very high precision. This allows, among other things, to measure the variations of the Earth-Moon distance with a precision equivalent to the size of a hair!

It can be shown that the time signal which corresponds to a comb of frequencies consists of a regular succession of light pulses, called a pulse train. These pulses are ultra-short and have a duration of one millionth of a billionth of a second, or even less!

There are currently two main methods for generating a pulse train either via a pulsed laser (very variable) or via a passive optical cavity (not very powerful). However, for certain applications (LiDAR), it is necessary to have a pulse train that is both energetic and ultra-stable.

Recent research carried out by the OPERA-Photonique Laboratory – École polytechnique de Bruxelles –  published in the journal Nature Photonics, shows the existence of new ultra-stable and high-power cavity solitons: active cavity solitons.

This new type of universal and hybrid soliton could trigger many experiments on different platforms, especially in the field of integrated optics where passive resonators have the monopoly, but where applications outside laboratories are slow to appear. This new concept is not limited to the generation of solitons. Thanks to this new hybrid cavity, components inducing a lot of losses (crystal, particular fiber, etc.) can now be placed in a resonator, opening the way to the study of phenomena hitherto inaccessible experimentally. The invention is the subject of a patent application filed in the name of the ULB.

Provided by ULB

Unhealthy Patterns of Diet, Exercise, and Sleep Linked to High Risk of Cardiovascular Disease in Autistic People (Medicine)

Autistic people have far greater risks of long term physical health conditions than others, but the reasons for this remain unclear. New research from the University of Cambridge suggests that unhealthy lifestyle habits may be an important contributing factor. 

“These findings help us to better understand the experiences of autistic adults, and have wider implications for quality of life. We need to understand the reasons for restricted diet, limited exercise, and lack of sleep, to provide better support.”

Elizabeth Weir

The results are published today in the journal Molecular Autism.

Earlier research suggests that autistic people die 16-35 years younger than expected, and that greater health problems may contribute to this risk. The present study is the first to consider the diet, exercise, and sleep patterns of autistic adults and how these patterns may relate to health outcomes.

The team at the Autism Research Centre in Cambridge developed an anonymous, online survey about lifestyle choices and daily habits, personal medical history, and family medical history. The final study included 1,183 autistic adults and 1,203 non-autistic adults aged 16-90 years.

The results showed that autistic adults were far less likely than non-autistic adults to meet very minimal health recommendations for diet, exercise, and sleep. Autistic adults were also far more likely to have atypical eating patterns (including limited diet) and sleep disturbance. They were more likely to be underweight or obese than non-autistic individuals.

These poor lifestyle habits were associated with greater risk of cardiovascular conditions such as high blood pressure, heart disease, and stroke among autistic males, and this was a stronger association even than a family history of a cardiovascular condition. Though it is not possible to say conclusively that a poorer lifestyle led to cardiovascular problems, the findings provide the first indication that promoting healthy choices regarding diet, exercise, and sleep may help to reduce the excess risks of health conditions in autistic adults. 

While the results indicate that there may be other biological or environmental factors that leave autistic individuals at greater risk of health conditions, they also provide a clear target for intervention. Difficulties with maintaining a healthy lifestyle may also have knock-on effects beyond physical health, including limiting opportunities for social interaction (which may centre around mealtimes or exercise), and could contribute to worsening mental health, and affect employment or education.

The lead researcher of the study, Elizabeth Weir, a PhD student at the Autism Research Centre in Cambridge, said: “These findings help us to better understand the experiences of autistic adults, and have wider implications for quality of life. We need to understand the reasons for restricted diet, limited exercise, and lack of sleep, to provide better support. This may include programmes for health education, and additional mental health support or supported living and working schemes.”

Dr Carrie Allison, Director of Research Strategy at the Autism Research Centre and a member of the research team, said: “The challenges we see among autistic children regarding lifestyle behaviours extend into adulthood. Given the implications for risk of chronic disease and length of life, it is critical that we work to identify effective strategies for supporting health choices by autistic people of all ages.”

Professor Simon Baron-Cohen, Director of the Autism Research Centre and a member of the team, said: “The wider picture suggests that autistic adults experience vulnerability in a variety of contexts, and this is just one new area that we should consider. Seeing that autistic adults are having such a hard time comparatively with healthy lifestyle habits has clear healthcare and policy implications: we need to create new and better support systems tailored to the specific needs of autistic people.”

Weir, E.,  et al. An investigation of the diet, exercise, sleep, BMI, and health outcomes of autistic adults. Molecular Autism 12, 31 (2021). DOI: 10.1186/s13229-021-00441-x

Funding for this project was generously provided by the Autism Research Trust, the Rosetrees Trust, and the Cambridge and Peterborough NHS Foundation Trust, the Corbin Charitable Trust, the MRC, the Wellcome Trust and the Innovative Medicines Initiative.

Provided by University of Cambridge