Culture

"Why do plants have thorns?" is an easy question: The thorns help protect against hungry animals that like to munch on the plants. "Where do thorns come from?" is a more complicated question -- but Yale scientists have found an answer.

Their insight, reported in the June 18 issue of Current Biology, may help change the way oranges and other crops are grown.

First, a primer for non-botanists: Many plants have sharp, spiky armor that can be classified as thorns, prickles or spines.

Rose bushes do not have thorns; they have prickles, as do raspberry and blackberry bushes. Prickles are like thick hairs on your arm, and in roses and other prickly plants, the prickles grow from their epidermis, or "skin," said Vivian Irish, chair and the Eaton Professor of Molecular, Cellular and Developmental Biology and senior author of the study.

Other plants, including cacti, have spines, another type of sharp, pointy weaponry that forms instead of leaves. Thorns arise from shoots in plants such as bougainvillea, hawthorn and citrus.

Irish, who is also professor of ecology and evolutionary biology, was fascinated by thorns that grow on old honey locust trees, commonly found along the streets of New Haven and other urban areas. While most honey locusts have been bred so that they no longer have thorns, some older trees with dangerous, foot-long thorns still exist. As a plant scientist, she was intrigued by how these structures arose, but she put off investigating the question for decades.

As it happens, she is also an expert on stem cells. And as it turns out, stem cells can explain thorns.

Irish and her research team first showed that, in citrus plants, thorns arise from the plants' stem cell populations. Unlike typical stem cells in animals or plants, which continue to divide, thorn stem cells undergo a programmed arrest. The scientists found that two regulators of stem cell production, TI1 and TI2, gradually shut down stem cell activity in the developing thorn, so that it tapers off until nothing is left but the sharp pointy end.

When the researchers genetically eliminated the two regulators, stem cell activity continued, and instead of thorns, the citrus plants produced new branches.

The insight could lead to orchards of orange trees with more fruit-bearing branches -- ones that pose less danger to laborers who pick the fruit, Irish said.

What The Study Did: The association of sociodemographic characteristics with reported incidence, knowledge and behavior regarding COVID-19 among U.S. adults is examined in this survey study.

Authors: David Cutler, Ph.D., of Harvard University in Cambridge, Massachusetts, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2020.12403)

Editor's Note: The article includes conflicts of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

#  #  #

Media advisory: The full study is linked to this news release.

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time http://jamanetwork.com/journals/jamanetworkopen/fullarticle/10.1001/jamanetworkopen.2020.12403?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=061820

About JAMA Network Open: JAMA Network Open is the new online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.

What The Study Did: This survey study of patients with COVID-19 investigates how common the ability to taste and smell was reduced at the onset of the disease.

Authors: Fabio Ferreli, M.D., of the Humanitas Clinical and Research Center in Milan, Italy, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamaoto.2020.1155)

Editor's Note: Please see the articles for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

#  #  #

Media advisory: The full study is linked to this news release.

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/10.1001/jamaoto.2020.1155?guestAccessKey=2a1c0db0-8549-4f18-bb83-142c5f6bd5c6&utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=061820

"Using iPSC lines to study the functions of archaic human DNA is an untapped but very interesting approach," says senior author J. Gray Camp of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the University of Basel in Switzerland. "No one has ever been able to look at the role Neandertal DNA plays during development."

Studies have found that about two percent of the genomes of modern humans from outside Africa are composed of Neandertal DNA. This archaic DNA is a result of mating between the two groups tens of thousands of years ago.

In the new study, the team used resources from the Human Induced Pluripotent Stem Cells Initiative (HipSci), an international consortium that provides data and cell lines for research. Nearly all of the data and cell lines in HipSci are from people of UK and Northern European descent. The researchers analyzed this cell line resource for its Neandertal DNA content and annotated functional Neandertal variants for each of the cell lines.

"Some Neandertal alleles have relatively high frequency in this population," Camp explains. "Because of that, this iPSC resource contains certain genes that are homozygous for Neandertal alleles, including genes associated with skin and hair color that are highly prevalent in Europeans."

Camp's team used four cell lines to generate brain organoids and generated single-cell RNA sequencing data to analyze their cell composition. They showed that this transcriptomic data could be used to track Neandertal-derived RNA across developmental processes. "This is a proof-of-principal study showing that you can use these resources to study the activity of Neandertal DNA in a developmental process," Camp says. "The real challenge will be scaling up the number of lines in one experiment, but this is already starting to be possible."

Camp notes that this research could be expanded to study other ancient human populations, including Denisovans, which have genes that are present primarily in Oceanian populations. His team also plans to continue studying Neandertal alleles using HipSci and other resources. "Organoids can be used to study a number of different developmental processes and phenotypes controlled by Neandertal DNA, including the intestinal tract and digestion, cognition and neural function, and the immune response to pathogens," he concludes.

The researchers have generated a web browser with this information to make the data easily accessible for future research.

An international group of researchers has tackled the controversial question of when measles first emerged, finding it could be linked to the rise of large cities. The team sequenced the genome of a measles strain from 1912 and looked backwards to assess when the virus likely arose in human populations, dating this at around 6th century BCE.

Alongside the findings published in Science, Australian evolutionary experts from the University of Sydney and University of Melbourne have published a complementary Perspective, proposing that similarly refining research about when COVID-19 and other zoonotic diseases emerged will assist in understanding how such pathogens jump from animals to humans.

University of Sydney Professor Simon Ho, corresponding author of the Science commentary, said the research could help efforts to pinpoint the time of emergence of measles in humans.

"Obtaining genomic data from RNA viruses such as the measles virus, which degrade rapidly in the environment, continues to be extremely challenging," said Professor Ho from the School of Life and Environmental Sciences.

"The sequencing of this measles genome by Ariane Düx, Sébastian Calvignac-Spencer and their colleagues is a profound achievement.

"It's very difficult to pinpoint exactly when and where pathogens such as viruses and bacteria jump into humans. Sometimes these jumps happen and they fizzle out. But sometimes they take hold and spread across the globe.

"For any particular pathogen, the timing of the jump must have occurred between two time points: when it split from its nearest known relative and when we look at the pathogen in humans and trace the lineages back to the common ancestor."

Professor Ho said although the human COVID-19 SARS-CoV-2 virus split from its closest known relative - another coronavirus from a horseshoe bat - about 30 to 40 years ago, the jump to humans most likely happened more recently.

"Had the coronavirus jumped from its animal host to a human much earlier than November or December last year, it probably would have been detected," he said.

Professor Ho, who runs the Molecular Ecology, Evolution and Phylogenetics lab in the Faculty of Science, said just as tracing the emergence of measles strongly suggests it was associated with the rise of large cities thousands of years ago, it is important to also understand more about COVID-19 to protect against and fight the pandemic.

"The chance of a virus jumping between species will generally increase with the amount of contact," said Professor Ho, referring to the fact that as a species, human civilisation is increasingly encroaching into the habitat of wild animals.

"We can see this process happening in zoos, where viruses can jump between species that would not normally be found together in the wild.

He said: "More work needs to be done to understand the diversity of viruses and their distribution in wildlife."

Humans have drawn technological inspiration from fish scales going back to ancient times: Romans, Egyptians, and other civilizations would dress their warriors in scale armor, providing both protection and mobility. Now, using advanced X-ray imaging techniques, Lawrence Berkeley National Laboratory (Berkeley Lab) scientists have characterized carp scales down to the nanoscale, enabling them to understand how the material is resistant to penetration while retaining flexibility.

The researchers used powerful X-ray beams at Berkeley Lab's Advanced Light Source (ALS) to watch how the fibers in carp scales react as stress is applied. As they wrote in their paper, published recently in the journal Matter, what they found "may well provide further inspiration for the design of advanced synthetic structural materials with unprecedented toughness and penetration resistance."

"The structure of biological materials is absolutely fascinating," said lead author Robert Ritchie, of Berkeley Lab's Materials Sciences Division, who headed this work with Marc Meyers, a professor of nanoengineering and mechanical engineering at UC San Diego. "We like to mimic these properties in engineering materials, but the first step is to see how nature does it."

Fish scales have a hard outer shell with a softer inner layer that is tough and ductile. When something like a predator's teeth try to sink into the scales, the outer shell resists the penetration but the inner has to absorb all the excess load to keep the scale in one piece. How does it do this? It turns out that the fibers in the scale, which is made up of collagen plus minerals, are in a twisted orientation, called a Bouligand structure. When stress is applied to the material, the fibers rotate in sequence in order to absorb the excess load.

"It's called adaptive reorientation. It's like a smart material," said Ritchie, who is also a professor of materials science and engineering at UC Berkeley. "Using a technique called small angle X-ray scattering, we can follow that in real time using the synchrotron. We irradiate it with X-rays, and we can actually see the fibers rotating and moving."

The collagen that makes up human skin, on the other hand, is "all messed up like a bowl of spaghetti, but it can unravel and align to absorb energy, which makes skin incredibly resistant to tearing," Ritchie said. The Bouligand structure in the carp scale is much more organized but still makes for a very effective toughening mechanism.

The other noteworthy characteristic of a carp scale is the gradient between the hard and soft layers. "If we were making that as armor, we would have an interface between the hard and soft material. The interface is invariably a location where cracks and failures start," said Ritchie, an expert in how materials fail. "The way nature does it: Instead of having these interfaces where there's discontinuity between one material and another, nature makes a perfect gradient from the hard to the soft (tougher) material."

Working in collaboration with the researchers at UC San Diego, the team has previously studied the arapaima, an Amazonian freshwater fish whose scales are so tough they are impenetrable to piranha, as well as other species. For this study they chose the carp, a modern version of the ancient coelacanth fish, also known for having scales that act as armor.

Now that the deformation and failure mechanisms of carp scales have been characterized, trying to reproduce these properties in an engineering material is the next challenge. Ritchie noted that advances in 3D printing could provide a way to produce gradients the way nature does, and thus make a material that is both hard and ductile.

"Once we get a better handle on how to manipulate 3D printing, we can start to make more materials in the image of nature," he said.

Researchers at the University of California San Diego have developed a test that uses children's ability to assemble LEGO pieces to assess their spatial visualization ability. Spatial visualization is the ability to visualize 3D shapes in one's mind, which is tied to increased GPAs and graduation rates in STEM college students.

One tool to increase spatial visualization skills among college students is a mobile app, called Spatial Vis, which allows students to sketch 2D and 3D shapes on a touchscreen and was developed based on research at UC San Diego.

However, the researchers Lelli Van Den Einde and Nathan Delson, both teaching professors at the UC San Diego Jacobs School of Engineering, feel that it would be beneficial to start teaching spatial visualization skills at younger ages. Indeed, during the COVID19 pandemic they have seen increased requests for use of Spatial Vis by middle school and high school teachers because it works well for remote instruction. One challenge to overcome to enable the teaching of these skills is how to assess spatial visualization ability at lower grade levels.

At the college level, a widely used assessment is the Purdue Spatial Visualization Test: Rotations, or PSVT:R, which is a 20-minute timed test consisting of a series of multiple-choice questions that are geared towards students 13 and older. Van Den Einde and Delson wanted to develop an assessment that would be more suitable and engaging for students at lower grade levels. They turned to LEGO, which was designed with that younger age range in mind and is familiar to many children. To pass the test, students have to assemble a set of LEGO pieces into a specific shape, such as a whale or a small plane, while only being given a picture of the final shape but no step-by-step instructions. The time it takes students to build the correct solution is the metric used for assessment.

Van Den Einde and Delson, along with Jessica Tuazon, Development Engineer, and Daniel Yang, PhD student, will present the LEGO Assembly test at the American Society for Engineering Education conference, held virtually June 22 to 26. In order to validate the test, the researchers had students in two freshman engineering graphics courses take both the LEGO assembly test and the PSVT:R. Students took the tests both at the beginning and end of the quarter. During the course, they were trained with the Spatial Viz app. Test results show a statistically significant correlation between outcomes on the LEGO test and the PSVT:R.

"We think the LEGO assembly test is a suitable way to assess spatial visualization ability for elementary school age students," Van Den Einde said.

Delson added that the LEGO test shows that younger students get a tangible benefit from using Spatial Vis and improve their spatial visualization skills.

Van Den Einde and Delson cofounded eGrove Education Inc. to commercialize spatial visualization training. The Spatial Vis app is used by over 120 schools and 2000 students. The two UC San Diego teaching professors are now working on a version for lower grade levels to meet the demand which has increased due to remote instruction.

The app includes automatic grading of student sketches, and hints when students are stuck. The researchers will be modifying their hint feedback, so the app is more suitable for K-12 students and encourages students to be persistent and solve assignments with only minimal hints.

A new study of the microbial settlers on old paintings, sculptures, and other forms of art charts a potential path for preserving, restoring, and confirming the geographic origin of some of humanity's greatest treasures.

Genetics scientists with the J. Craig Venter Institute (JCVI), collaborating with the Leonardo da Vinci DNA Project and supported by the Richard Lounsbery Foundation, say identifying and managing communities of microbes on art may offer museums and collectors a new way to stem the deterioration of priceless possessions, and to unmask counterfeits in the $60 billion a year art market.

Manolito G. Torralba, Claire Kuelbs, Kelvin Jens Moncera, and Karen E. Nelson of the JCVI, La Jolla, California, and Rhonda Roby of the Alameda California County Sheriff's Office Crime Laboratory, used small, dry polyester swabs to gently collect microbes from centuries-old, Renaissance-style art in a private collector's home in Florence, Italy. Their findings are published in the journal Microbial Ecology .

The genetic detectives caution that additional time and research are needed to formally convict microbes as a culprit in artwork decay but consider their most interesting find to be "oxidase positive" microbes primarily on painted wood and canvas surfaces.

These species can dine on organic and inorganic compounds often found in paints, in glue, and in the cellulose in paper, canvas, and wood. Using oxygen for energy production, they can produce water or hydrogen peroxide, a chemical used in disinfectants and bleaches.

"Such byproducts are likely to influence the presence of mold and the overall rate of deterioration," the paper says.

"Though prior studies have attempted to characterize the microbial composition associated with artwork decay, our results summarize the first large scale genomics-based study to understand the microbial communities associated with aging artwork."

The study builds on an earlier one in which the authors compared hairs collected from people in the Washington D.C., and San Diego, CA. areas, finding that microbial signatures and patterns are geographically distinguishable.

In the art world context, studying microbes clinging to the surface of a work of art may help confirm its geographic origin and authenticity or identify counterfeits.

Lead author Manolito G. Torralba notes that, as art's value continues to climb, preservation is increasingly important to museums and collectors alike, and typically involves mostly the monitoring and adjusting of lighting, heat, and moisture.

Adding genomics science to these efforts offers advantages of "immense potential."

The study says microbial populations "were easily discernible between the different types of substrates sampled," with those on stone and marble art more diverse than wood and canvas. This is "likely due to the porous nature of stone and marble harboring additional organisms and potentially moisture and nutrients, along with the likelihood of biofilm formation."

As well, microbial diversity on paintings is likely lower because few organisms can metabolize the meagre nutrients offered by oil-based paint.

"Though our sample size is low, the novelty of our study has provided the art and scientific communities with evidence that microbial signatures are capable of differentiating artwork according to their substrate," the paper says.

"Future studies would benefit from working with samples whose authorship, ownership, and care are well-documented, although documentation about care of works of art (e.g., whether and how they were cleaned) seems rare before the mid-twentieth century."

"Of particular interest would be the presence and activity of oil-degrading enzymes. Such approaches will lead to fully understanding which organism(s) are responsible for the rapid decay of artwork while potentially using this information to target these organisms to prevent degradation."

"Focusing on reducing the abundance of such destructive organisms has great potential in preserving and restoring important pieces of human history."

Biology in Art

The paper was supported by the US-based Richard Lounsbery Foundation as part of its "biology in art" research theme, which has also included seed funding efforts to obtain and sequence the genome of Leonardo da Vinci.

The Leonardo da Vinci DNA Project involves scientists in France (where Leonardo lived during his final years and was buried), Italy (where his father and other relatives were buried, and descendants of his half-brothers still live), Spain (whose National Library holds 700 pages of his notebooks), and the US (where forensic DNA skills flourish).

The Leonardo project has convened molecular biologists, population geneticists, microbiologists, forensic experts, and physicians working together with other natural scientists and with genealogists, historians, artists, and curators to discover and decode previously inaccessible knowledge and to preserve cultural heritage.
 

Related news release: Leonardo da Vinci's DNA: Experts unite to shine modern light on a Renaissance master http://bit.ly/2FG4jJu

Measuring Leonardo da Vinci's "quick eye" 500 years later.

Could he have played major-league baseball?

Famous art historians and biographers such as Sir Kenneth Clark and Walter Isaacson have written about Leonardo da Vinci's "quick eye" because of the way he accurately captured fleeting expressions, wings during bird flight, and patterns in swirling water. But until now no one had tried to put a number on this aspect of Leonardo's extraordinary visual acuity.

David S. Thaler of the University of Basel, and a guest investigator in the Program for the Human Environment at The Rockefeller University, does, allowing comparison of Leonardo with modern measures. Leonardo fares quite well.

Thaler's estimate hinges on Leonardo's observation that the fore and hind wings of a dragonfly are out of phase -- not verified until centuries later by slow motion photography (see e.g. https://youtu.be/Lw2dfjYENNE?t=44).

To quote Isaacson's translation of Leonardo's notebook: "The dragonfly flies with four wings, and when those in front are raised those behind are lowered."

Thaler challenged himself and friends to try seeing if that's true, but they all saw only blurs.

High-speed camera studies by others show the fore and hind wingbeats of dragonflies vary by 20 to 10 milliseconds -- one fiftieth to one hundredth of a second -- beyond average human perception.

Thaler notes that "flicker fusion frequency" (FFF) -- akin to a motion picture's frames per second -- is used to quantify and measure "temporal acuity" in human vision.

When frames per second exceed the number of frames the viewer can perceive individually, the brain constructs the illusion of continuous movement. The average person's FFF is between 20 to 40 frames per second; current motion pictures present 48 or 72 frames per second.

To accurately see the angle between dragonfly wings would require temporal acuity in the range of 50 to 100 frames per second.

Thaler believes genetics will account for variations in FFF among different species, which range from a low of 12 in some nocturnal insects to over 300 in Fire Beetles. We simply do not know what accounts for human variation. Training and genetics may both play important roles.

 
"Perhaps the clearest contemporary case for a fast flicker fusion frequency in humans is in American baseball, because it is said that elite batters can see the seams on a pitched baseball," even when rotating 30 to 50 times per second with two or four seams facing the batter. A batter would need Leonardo-esque FFF to spot the seams on most inbound baseballs.
 

Thaler suggests further study to compare the genome of individuals and species with unusually high FFF, including, if possible, Leonardo's DNA.
 

Flicker fusion for focus, attention, and affection
  

In a companion paper, Thaler describes how Leonardo used psychophysics that would only be understood centuries later -- and about which a lot remains to be learned today -- to communicate deep beauty and emotion. 

Leonardo was master of a technique known as sfumato (the word derived from the Italian sfumare, "to tone down" or "to evaporate like smoke"), which describes a subtle blur of edges and blending of colors without sharp focus or distinct lines.

Leonardo expert Martin Kemp has noted that Leonardo's sfumato sometimes involves a distance dependence which is akin to the focal plane of a camera. Yet, at other times, features at the same distance have selective sfumato so simple plane of focus is not the whole answer.

Thaler suggests that Leonardo achieved selective soft focus in portraits by painting in overcast or evening light, where the eyes' pupils enlarge to let in more light but have a narrow plane of sharp focus. 

To quote Leonardo's notebook, under the heading "Selecting the light which gives most grace to faces": "In the evening and when the weather is dull, what softness and delicacy you may perceive in the faces of men and women."  In dim light pupils enlarge to let in more light but their depth of field decreases.
 

By measuring the size of the portrait's pupils, Thaler inferred Leonardo's depth of focus. He says Leonardo likely sensed this effect, perhaps unconsciously in the realm of his artistic sensibility. The pupil / aperture effect on depth of focus wasn't explained until the mid-1800s, centuries after Leonardo's birth in Vinci, Italy in 1452.

What about selective focus at equal distance? In this case Leonardo may have taken advantage of the fovea, the small area on the back of the eye where detail is sharpest.

Most of us move our eyes around and because of our slower flicker fusion frequency we construct a single 3D image of the world by jamming together many partially in-focus images. Leonardo realized and "froze" separate snapshots with which we construct ordinary perception.

Says Thaler: "We study Leonardo not only to learn about him but to learn about ourselves and further human potential."

Thaler's papers (at https://bit.ly/2WZ2cwo and https://bit.ly/2ZBj7Hi) evolved from talks at meetings of the Leonardo da Vinci DNA Project in Italy (2018), Spain and France (2019).

They form part of a collection of papers presented at a recent colloquium in Amboise, France, now being readied for publication in a book: Actes du Colloque International d’Amboise: Leonardo de Vinci, Anatomiste. Pionnier de l’Anatomie comparée, de la Biomécanique, de la Bionique et de la Physiognomonie. Edited by Henry de Lumley, President, Institute of Human Paleontology, Paris, and originally planned for release in late spring, 2020, publication was delayed by the global virus pandemic but should be available at CNRS Editions in the second half of the summer.

Other papers in the collection cover a range of topics, including how Leonardo used his knowledge of anatomy, gained by performing autopsies on dozens of cadavers, to achieve Mona Lisa's enigmatic smile.

Leonardo also used it to exact revenge on academics and scientists who ridiculed him for lacking a classical education, sketching them with absurdly deformed faces to resemble birds, dogs, or goats. 

De Lumley earlier co-authored a 72-page monograph for the Leonardo DNA Project: "Leonardo da Vinci: Pioneer of comparative anatomy, biomechanics and physiognomy.".

Sleeping less than normal impacts how we feel the next morning.

"Not in the sense that we have more negative feelings, like being down or depressed. But participants in our study experienced a flattening of emotions when they slept less than normal. They felt less joy, enthusiasm, attention and fulfilment," says Associate Professor Ingvild Saksvik-Lehouillier at the Norwegian University of Science and Technology's (NTNU) Department of Psychology.

Most sleep research is done in laboratories, but Saksvik-Lehouillier and the NTNU research team studied participants who slept at home.

The participants first spent seven nights in their own bed, and slept as long as they usually do.

Three of the mornings they conducted a set of tests. Next, the participants slept two hours less than normal for three nights. On two of the mornings they went through the same tests.

"We all have different sleep patterns. The point of having the participants sleep at home was to keep everything as similar to daily life as possible. In the imposed sleep deprivation phase, participants crawled under their covers two hours later than they normally did, and had to get up at their usual time," says Saksvik-Lehouillier.

The practical testing took place about an hour and a half after the participants got up - and without having had any coffee.

They were shown 365 different pictures with random letters displayed on a computer screen over a period of 14 minutes. If the image did not contain the letter x, they were told to press the space bar, and if there was an x ??in the image, they were supposed to do nothing.

"We tested responsiveness and accuracy. The reaction time went down after the participants had been sleep deprived, but the error rate went up. It seems that we react more quickly to compensate for lower concentration. Then there'll be more mistakes. It may be smart to avoid activities that require a high level of accuracy the morning after sleeping less than usual," Saksvik-Lehouillier says.

Previous studies have shown that sleep deprivation may have about the same effect on driving as alcohol does.

Whereas the participants performed better and better each day they took the test after sleeping normally, they scored worse on accuracy each day after a night of insufficient sleep.

"We know that sleep is important for learning. Maybe that's what we're seeing here," says Saksvik-Lehouillier.

In the second part of the test, participants answered a questionnaire to identify 20 positive and negative emotions.

"We didn't find clear differences when it came to the negative emotions, but there were marked differences for the positive ones. Positive feelings scored worse after just one night of reduced sleep, and dropped even more after three nights. I think this is a really interesting find. We already know that fewer positive emotions have a major impact on mental health. We also know that poor sleep is included in virtually all mental health diagnoses," Saksvik-Lehouillier said.

In terms of how long the lack of good feelings lasts after sleep deprivation, she says the study did not address that, but the research team plans to investigate the duration of this state of mind.

It's not just in Norway that people are sleeping less than they used to -- it's an international trend, especially for people who work full-time.

"It's easy for us to go to bed later than we should, especially when we think, 'I just have to finish watching this series.' But we still have to get up to go to work, or study, or deliver our kids to kindergarten. This contributes to getting too little sleep. How long we sleep is just part of the picture, but when we sleep is also important. An irregular circadian rhythm can be worse than sleeping too little. Going to bed and getting up at the same time is recommended," says Saksvik-Lehouillier. She worries most about young people.

"Adolescents have a greater need for sleep and are a vulnerable group. They feel they need to be available online, there are a lot of entertainment temptations - and maybe the cell phone even goes to bed with them. But they still have to get up the next morning to go to school. Sleep deprivation can quickly become an issue. Many teens experience sleep problems during exam times. For them, it may be a comfort to know that studies show that short-term lack of sleep doesn't affect their ability to reflect and discuss what they're learning.

Long-term studies conducted among shift workers who sleep too little over a long period of time show major negative consequences for their health, including a significantly increased risk for diseases such as cancer and diabetes.

"Sleep is individual. Not everyone needs to sleep seven and a half hours every night. And we're A and B people. Some of us like to stay up till the wee hours, others love to rise and shine early in the morning. The most important thing is how you feel. If you're in a good mood and alert when you get up, those are indications that your sleep habits are working for you," says Saksvik-Lehouillier.

Shorter sleep times aren't entirely negative either. The body compensates for shorter periods of time with more effective sleep. The time spent awake in bed is also less.

This release has been removed upon request of the submitting institution. Please contact Nancy Bazilchuk at nancy.bazilchuk@ntnu.no for more information.

Journal

Psychological Science

DOI

10.1177/0956797620904154

Last year, the Advanced LIGO-VIRGO gravitational-wave detector network recorded data from 35 merging black holes and neutron stars. A great result - but what did they miss? According to Dr Rory Smith from the ARC Centre of Excellence in Gravitational Wave Discovery at Monash University in Australia - it's likely there are another 2 million gravitational wave events from merging black holes, "a pair of merging black holes every 200 seconds and a pair of merging neutron stars every 15 seconds" that scientists are not picking up.

Dr Smith and his colleagues, also at Monash University, have developed a method to detect the presence of these weak or "background" events that to date have gone unnoticed, without having to detect each one individually.
The method - which is currently being test driven by the LIGO community - "means that we may be able to look more than 8 billion light years further than we are currently observing," Dr Smith said.

"This will give us a snapshot of what the early universe looked like while providing insights into the evolution of the universe."

The paper, recently published in the Royal Astronomical Society journal, details how researchers will measure the properties of a background of gravitational waves from the millions of unresolved black hole mergers.

Binary black hole mergers release huge amounts of energy in the form of gravitational waves and are now routinely being detected by the Advanced LIGO-Virgo detector network. According to co-author, Eric Thrane from OzGrav-Monash, these gravitational waves generated by individual binary mergers "carry information about spacetime and nuclear matter in the most extreme environments in the Universe. Individual observations of gravitational waves trace the evolution of stars, star clusters, and galaxies," he said.

"By piecing together information from many merger events, we can begin to understand the environments in which stars live and evolve, and what causes their eventual fate as black holes. The further away we see the gravitational waves from these mergers, the younger the Universe was when they formed. We can trace the evolution of stars and galaxies throughout cosmic time, back to when the Universe was a fraction of its current age."

The researchers measure population properties of binary black hole mergers, such as the distribution of black hole masses. The vast majority of compact binary mergers produce gravitational waves that are too weak to yield unambiguous detections - so vast amounts of information is currently missed by our observatories.

"Moreover, inferences made about the black hole population may be susceptible to a 'selection bias' due to the fact that we only see a handful of the loudest, most nearby systems. Selection bias means we might only be getting a snapshot of black holes, rather than the full picture," Dr Smith warned.

The analysis developed by Smith and Thrane is being tested using real world observations from the LIGO-VIRGO detectors with the program expected to be fully operational within a few years, according to Dr Smith.

A new study suggests that denser places, assumed by many to be more conducive to the spread of the coronavirus that causes COVID-19, are not linked to higher infection rates. The study, led by a researcher at the Johns Hopkins Bloomberg School of Public Health, also found that dense areas were associated with lower COVID-19 death rates.

The study was published online June 18 in the Journal of the American Planning Association.

For their analysis, the researchers examined SARS-CoV-2 infection rates and COVID-19 death rates in 913 metropolitan counties in the U.S. When other factors such as race and education were taken into account, the authors found that county density was not significantly associated with county infection rate.

The authors also found that denser counties, as compared to more sprawling ones, tended to have lower death rates--possibly because they enjoyed a higher level of development including better health care systems.

On the other hand, the authors found that higher coronavirus infection and COVID-19 mortality rates in counties are more related to the larger context of metropolitan size in which counties are located. Large metropolitan areas with a higher number of counties tightly linked together through economic, social, and commuting relationships are the most vulnerable to the pandemic outbreaks.

"These findings suggest that urban planners should continue to practice and advocate for compact places rather than sprawling ones, due to the myriad well-established benefits of the former, including health benefits," says study lead author Shima Hamidi, PhD, a Bloomberg Assistant Professor of American Health in Environmental Challenges in the Department of Environmental Health and Engineering at the Bloomberg School.

Recent polls suggest that many Americans now consider an exodus from big cities likely, possibly due to the belief that more density equals more infection risk. Some government officials have posited that urban density is linked to the transmissibility of the virus.

Hamidi, whose research background is in urban planning and architecture, and colleagues found otherwise. She and her colleagues, Sadegh Sabouri, a doctoral student, and Reid Ewing, Distinguished Professor of City and Metropolitan Planning at the University of Utah, examined data from January 20 through May 25 on 913 metropolitan U.S. counties, using an approach known as Structural Equation Modeling and taking into account factors such as population size, education levels, and demographic variables including age and race, and health care infrastructure such as ICU bed capacity.

The researchers determined from this analysis that, when controlling for other factors, a measure of density that they termed the "activity density"--which takes into account both residents and workers in a given area--did not have a significant association with SARS-CoV-2 infection rates. Higher activity density did, however, have a significant association with COVID-19 death rates, but an unexpected one.

"The fact that density is unrelated to confirmed virus infection rates and inversely related to confirmed COVID-19 death rates is important, unexpected, and profound," says Hamidi. "It counters a narrative that, absent data and analysis, would challenge the foundation of modern cities and could lead to a population shift from urban centers to suburban and exurban areas."

The analysis found that after controlling for factors such as metropolitan size, education, race, and age, doubling the activity density was associated with an 11.3 percent lower death rate. The authors say that this is possibly due to a faster and more widespread adoption of social distancing practices and better quality of health care in areas of denser population.

The authors conclude that a higher county population, a higher proportion of people age 60 and up, a lower proportion of college-educated people, and a higher proportion of African Americans were all associated with a greater infection rate and mortality rate.

The researchers have been updating the data as the pandemic progresses, and are finding that the associations they have uncovered are becoming even stronger, Hamidi says. The team is also conducting a longitudinal study that tracks the relationships among density, the county-level SARS-CoV-2 infection rates and mortality rates, and explanatory factors as they change over time, and have found consistent results regarding the inverse relationship between density and the COVID-19 mortality rate.

"Does Density Aggravate the COVID-19 Pandemic? Early Results and Lessons for Planners" was written by Shima Hamidi, Sadegh Sabouri, and Reid Ewing.

Two mutations identified in individuals with developmental and epileptic brain disease can be traced back to the same ion channel. Researchers have now elucidated how both independent mutations affect the channel's function: by making it overly active and highly sensitive to stimulation. The findings are an important step towards unraveling what causes the patients' symptoms.

Developmental and epileptic encephalopathies are a heterogeneous group of disorders characterized by epilepsy and intellectual disability. Genetic analysis pointed to the involvement of an ion channel called TRPM3. This channel is activated by heat and a variety of chemical ligands. It helps us detect noxious heat, and plays an important role in inflammatory pain.

"Two different mutations in the gene encoding TRPM3 were identified in nine individuals with a diagnosed developmental and epileptic encephalopathy," explains Thomas Voets (VIB-KU Leuven) whose research is focused on ion channels and their role in pain and heat sensation. "Since the functional consequences of the mutations remained elusive, we set out to understand how disturbances of this particular ion channel can cause intellectual disability and epileptic seizures."

An overly active channel

Voets, together with his colleague Joris Vriens (KU Leuven) and their team at the Laboratory for Ion Channel Research, could show that both mutations affect TRPM3 channel gating.

"Clinical reports pointed out that next to the seizures and intellectual disability, several of the affected patients showed altered sensitivity to heat and pain, which hinted at a modified altered function of TRPM3," says Vriens.

The team could indeed demonstrate that both mutations lead to a significant gain in channel activity. Not only was basal activity increased, they also observed a higher sensitivity to stimulation by an endogenous neurosteroid and heat. Most strikingly, one of the two mutations resulted in even more pronounced functional alterations, including anomalous activation and reduced sensitivity to an anticonvulsant drug.

"The two mutations identified in the TRPM3 gene give rise to channels with substantially altered functional properties. Whereas the individual effects of both mutations differ, both can be considered as strong gain-of-function mutants, with increased activity, both under basal conditions and when stimulated," says Voets.

"These two mutations also provide the first genetic evidence that link TRPM3 to a pain phenotype in humans," adds Vriens. The researchers propose that this increased channel activity may lie at the basis of seizure development and neurodevelopmental symptoms in patients.

Our planet exists within the vicinity of thousands of Near-Earth Objects (NEOs), some of which - ?Potentially Hazardous Asteroids (PHAs)? - ?carry the risk of impacting Earth causing major damage to infrastructure and loss of life. Methods to mitigate such a collision are highly desirable. A new paper published in EPJ Special Topics, authored by Flaviane Venditti, Planetary Radar Department, Arecibo Observatory, University of Central Florida, Arecibo, suggests the use of a tether assisted system to prevent PHA impact.

The method suggested by Venditti and her colleagues involves using the tether - ?previously suggested for other uses, such as space/lunar elevators and tethered satellite system? - ?to connect the threatening PHA to another, smaller, asteroid, thus changing the centre of mass of the two and hopefully raising the PHA to a safer orbit.

Each potential PHA impact mitigation method carries with it, its own set of benefits and risks. A considerable risk associated with 'high-impact' mitigation techniques, such as the detonation of explosives at the surface of the PHA, is fragmentation. This makes methods which gradually alter the orbit of a PHA, and thus prevent the break up of such an object, look like a less risky prospect. The tether system carries with it little risk of causing fragmentation and smaller pieces of the PHA falling to earth, something which could itself cause widespread damage.

Using the asteroid Bennu as a test subject, the team used computer simulations to calculate the dynamics of such a tether system for a variety of different initial conditions, concluding that it would be feasible for use as a planetary defence system. The team also suggest that the system could be of use in both the study and potential mining of NEOs and other asteroids.

One of the likely drawbacks of such a method is the fact that it could require a longer lead time than many high impact methods which quickly deliver kinetic energy to a PHA to knock it out of orbit. Thus, the continued cataloguing of such objects is needed if such a method is ever to be viable.

Plasma astrophysicists at KU Leuven have created the first self-consistent simulation of the physical processes that occur during a solar flare. The researchers used Flemish supercomputers and a new combination of physical models.

Solar flares are explosions on the surface of the Sun that release an enormous amount of energy, equivalent to a trillion 'Little Boy' atomic bombs exploding at the same time. In extreme cases, solar flares can disable radio connections and power stations on Earth, but they are also at the basis of stunning space weather phenomena. The Northern Lights, for instance, are linked to a solar flare that disturbs the magnetic field of the Sun to such an extent that a bubble of solar plasma can escape from the atmosphere of the Sun.

Unique simulation

Thanks to satellites and solar telescopes, we already understand quite a lot about the physical processes that take place during a solar flare. For one thing, we know that solar flares convert energy from magnetic fields into heat, light and motion energy very efficiently.

In science textbooks, these processes are commonly visualised as the standard 2-D solar flare model. The details of this illustration, however, have never been confirmed. This is because creating a fully consistent simulation is a huge challenge, given that both macroscopic effects (we're talking several tens of thousands of kilometres here: larger than Earth) and microscopic particle physics have to be taken into account.

Researchers at KU Leuven have now been able to create such a simulation. As part of his doctoral research, Wenzhi Ruan worked on the simulation with his colleagues in the team of Professor Rony Keppens at the KU Leuven Department of Plasma Astrophysics. The researchers used the computational power of Flemish supercomputers as well as a new combination of physical models in which the microscopic effects of accelerated charged particles were taken into account in a macroscopic model.

From textbook illustration to self-consistent model

"Our work also makes it possible to calculate the energy conversion efficiency of a solar flare," Professor Rony Keppens explains. "We can calculate this efficiency by combining the strength of the Sun's magnetic field at the feet of the flare with the speed at which those feet move. If we can complete our observations in time, that is, because everything happens within a time span of tens of seconds to a few minutes."

"We converted the results of the numerical simulation into virtual observations of a solar flare, whereby we imitated telescopes in all relevant wavelengths. This allowed us to upgrade the standard solar flare model from a textbook illustration to an actual model."