Culture

A single drop of seawater can contain a wide representation of ocean microbes from around the world - revealing novel insights into the ecology, evolution and biotechnology potential of the global microbiome. A new publication in Cell reports a staggering degree of biological diversity that defies contemporary definitions of microbial species, illuminates reasons behind challenges in metagenomic studies, and may even further understanding of how marine microbes respond to climate change.

"This unprecedented project uses a big data approach to read a large, randomized sample of genomes from the global microbiome, which we then explore to answer many types of questions," said Ramunas Stepanauskas, a senior research scientist at Bigelow Laboratory for Ocean Sciences and the senior author of the paper. "Our team's results provide a deeper understanding of microbial diversity in the ocean, new insights into energy sources and biosynthetic capabilities, and novel tools for the study of microbes in all environments."

The research team analyzed over 12,000 individual microbial genomes to build the Global Ocean Reference Genomes Tropics (GORG-Tropics) database. To their surprise, every cell they analyzed was genetically unique. In fact, few were similar enough that they would be considered the same species.

This new perspective on microbial diversity incorporates both local and global scales. The team used cutting-edge technologies in Bigelow Laboratory's Single Cell Genomics Center to analyze samples collected throughout the tropics and subtropics -- two thirds of the world's ocean -- to learn about global distribution patterns. They also examined local microbial diversity by reading the blueprints of over 6,000 individual cells captured from a single teaspoon of Sargasso Sea water.

The researchers found that cells in that sample contained at least a fifth of the genes that are common elsewhere in the tropical and subtropical ocean. This discovery indicates that ocean currents are effective at mixing up microbial life around the globe, transporting microbes far and wide to create diverse communities. It also highlights the power of single cell genomics to study the complexity of natural microbiomes in unprecedented detail.

"In the same way that we think of New York City as a melting pot, every teaspoon of the ocean is a microbial melting pot," Stepanauskas said. "The ocean is huge, and it's amazing how complex ecological and evolutionary processes take place in each tiny drop."

Recent breakthroughs in genomic technologies now allow scientists to rapidly generate and analyze enormous amounts of genetic information. The GORG initiative sequenced more microbes than all studies prior to 2013 combined, yielding numerous and diverse discoveries. MIT Institute Professor Penny Chisholm, Research Scientist Paul Berube, and Research Scientist Steven Biller helped collect field samples and used the data to gain insights into Prochlorococcus, the most abundant photosynthetic organism in the ocean. Stepanauskas' team uncovered a surprise in the genetic code of a group of proteobacteria - a previously unknown ability to photosynthesize.

"Genetic information can teach us a lot about ecology, and these may be photosynthetic organisms that were unnoticed before," said Maria Pachiadaki, a former Bigelow Laboratory postdoctoral researcher who is now an assistant scientist at Woods Hole Oceanographic Institution, and the lead author on the paper. "If experiments confirm what the genes suggest, this is an important microbial group to consider in ocean carbon studies."

The team also worked with Jim La Clair and Michael Burkart from University of California San Diego to identify microbes that could fuel novel biotechnology applications. By recording which chemicals specific microbes are able to produce, the GORG-Tropics database provides a roadmap to help other researchers choose which microbial groups to target for new antibiotics or anti-cancer medicines.

The researchers will continue mining the GORG-Tropics database for answers to diverse questions in future studies. Stepanauskas believes it has much more to reveal about how the ocean functions, how researchers can best wield genomic tools - and potentially even how scientists should re-define microbial species. They also hope to expand this project to the rest of the ocean, including temperate and polar regions and deep waters, which contain very different microorganisms.

"One of our main goals with the GORG initiative was to produce a powerful resource for the marine microbiology research community," said Julia Brown, a bioinformatician at Bigelow Laboratory and a study author. "We hope that scientists will be able to use this dataset in follow-up studies to answer questions no one has even thought of yet."

CHAPEL HILL, NC - December 12, 2019 - Scientists have known that a region of the brain called the central nucleus of the amygdala (CeA) plays a role in behaviors related to alcohol use and consumption in general. It's been less known which precise populations of brain cells and their projections to other brain regions mediate these behaviors. Now, UNC School of Medicine scientists discovered that specific neurons in the CeA contribute to reward-like behaviors, alcohol consumption in particular.

Published in the Journal of Neuroscience, this research pinpoints a specific neural circuit that when altered caused animal models to drink less alcohol.

"The fact that these neurons promote reward-like behavior, that extremely low levels of alcohol consumption activate these cells, and that activation of these neurons drive alcohol drinking in animals without extensive prior drinking experience suggests that they may be important for early alcohol use and reward," said senior author Zoe McElligott, PhD, assistant professor of psychiatry and pharmacology. "It's our hope that by understanding the function of this circuit, we can better predict what happens in the brains of people who transition from casual alcohol use to subsequent abuse of alcohol, and the development of alcohol use disorders."

McElligott, who is also a member of the UNC Bowles Center for Alcohol Studies, set out to investigate if a population of neurons that express a specific neuropeptide (neurotensin or NTS) contributes to reward-like behaviors and alcohol drinking. She was especially interested in these neurons in the context of inexperienced alcohol use, such as when a person first begins to drink alcohol. Also, NTS neurons are a subpopulation of other neurons in this CeA brain region that have been implicated in anxiety and fear - known as the somatostatin and corticotropin releasing factor neurons.

Using modern genetic and viral technologies in male mice, McElligott and colleagues found that selectively lesioning or ablating the NTS neurons in the CeA, while maintaining other types of CeA neurons, would cause the animals to drink less alcohol. This manipulation did not alter anxiety-like behavior. It also did not affect the consumption of other palatable liquids such as sucrose, saccharin, and bitter quinine solutions.

"We found that these NTS neurons in the CeA send a strong projection to the hindbrain, where they inhibit the parabrachial nucleus, near the brainstem," McElligott said.

Using optogenetics - a technique where light activates these neurons - the researchers stimulated the terminal projections of the CeA-NTS neurons in the parabrachial and found that this stimulation inhibited the neurons in the parabrachial. When the scientists stimulated this projection with a laser in one half of the animal's box, animals would spend more time where the stimulation would occur.

Animals also learned to perform a task to get the laser stimulation to turn on, and they would do this repeatedly, suggesting that they found this stimulation to be rewarding.

"Furthermore, when we stimulated this projection, animals would drink more alcohol as compared to when they had an opportunity to drink alcohol without laser stimulation," McElligott said. "In contrast to our study where we ablated the NTS neurons, laser stimulation of this parabrachial pathway also caused the animals to consume caloric and non-caloric sweetened beverages. When the animals were presented with regular food and a sweet food, however, laser stimulation did not enhance the consumption regardless of the mouse's hunger state. This suggests that different circuits may regulate the consumption of rewarding fluids and solids."

McElligott and her graduate student María Luisa Torruella Suarez, the first author of this study, hope to explore how alcohol experience may change these neurons over time.

"Would these cells respond differently after animals have been drinking high quantities of alcohol over time?" McElligott said. "We also want to discover which populations of neurons in the parabrachial are receiving inputs from these neurons. Fully understanding this circuit could be the key to developing therapeutics to help people with alcohol use disorders."

Most people who experience severe trauma recover their health. But 23 percent develop PTSD, a difficult-to-treat illness that combines intrusive thoughts about the trauma, avoidance of reminders of it, low mood and an exaggerated startle reaction. Which trauma victims will develop the disorder and which will be spared is not well understood.

A study just published in the journal Depression and Anxiety both offers new clues on identifying potential PTSD candidates among the population of trauma sufferers and suggests potential interventions that could prevent its development.

The study is the first to gather extensive data from trauma victims during the first 30 days after the traumatic event, a critical period says Matthew Price, associate professor of Psychological Sciences at the University of Vermont and lead author of the study.

"Getting PTSD is not like the flu where you wake up one day with a virus and feel sick," Price said. "It's a complex system where a range of symptoms develop, build on themselves and influence each other over time. After about a month, the die is cast, so to understand and prevent PTSD, it's very important to map the dynamics of how things develop early on."

The nature of the disease has made that difficult, Price says. Researchers either had little access to trauma victims, who often left the hospital abruptly, or weren't comfortable being interviewed numerous times during the acute post-trauma phase.

The new study took a novel approach. Using a mobile phone app, a non-intrusive method of gathering information, researchers were able to text trauma victims a series of questions, which they answered when it was convenient, in each of the 30 days after the trauma event.

The questions were crafted so they yielded day-by-day information about the key symptoms that characterize PTSD and were asked in such a way that researchers could track their development over time.

Two independent tracks

Then the research team used a statistical technique called short term dynamic modeling to determine which symptoms acted as influencers, causing other symptoms to develop and gain strength, which symptoms arose from those influencers and which operated independently.

"For one series of symptoms, the symptom chain looked a lot like fear conditioning," Price said. "People first had intrusive, unpleasant thoughts about what happened to them, which led them to avoid doing things that remind them of their trauma, and that avoidance led to hypervigilance." The sequence reflects a commonly accepted theoretical framework for PTSD development.

But feelings of depression seemed to operate independently of the fear conditioning symptoms, Price said.

"Depression wasn't influenced by other symptoms and wasn't an influencer; it was off on its own and self-perpetuating."

That's very different from full blown PTSD, Price said, where fear conditioning and depression are tightly integrated, and suggests a treatment approach that is very different from what is currently done.

"The most commonly used strategy right now is to wait and see," he said. "The research shows that, by contrast - as challenging as it is to treat victims soon after the trauma - it's critically important to intervene early to head off the development of full blown PTSD. Prevention is a preferred strategy because many individuals who go on to develop PTSD do not seek out treatment right away. Instead, these folks can suffer for months or years before getting the help they need."

The research suggests that intervention could happen along two tracks, Price said.

On the hand one hand, patients could undergo a form of exposure therapy to address the fear-based cluster of symptoms. On the other, a more cognitive-based approach could address developing depression.

Which trauma victims are most likely to develop PTSD?

The research findings suggest that those who are "having a strong reaction to trauma cues, who shortly after a trauma seem to be very reactive to things that remind them of their trauma, would probably be good people to look out for," Price says.

But the questions around PTSD are still very much unanswered, Price said.

"This research is trying to piece together what this process may look like as it unfolds so that we can start to develop treatments that might be able to deliver it in this very acute phase. There is much more work to do."

CHAMPAIGN, Ill. -- Scientists have known for decades that aerobic exercise strengthens the brain and contributes to the growth of new neurons, but few studies have examined how yoga affects the brain. A review of the science finds evidence that yoga enhances many of the same brain structures and functions that benefit from aerobic exercise.

The review, published in the journal Brain Plasticity, focused on 11 studies of the relationship between yoga practice and brain health. Five of the studies engaged individuals with no background in yoga practice in one or more yoga sessions per week over a period of 10-24 weeks, comparing brain health at the beginning and end of the intervention. The other studies measured brain differences between individuals who regularly practice yoga and those who don't.

Each of the studies used brain-imaging techniques such as MRI, functional MRI or single-photon emission computerized tomography. All involved Hatha yoga, which includes body movements, meditation and breathing exercises.

"From these 11 studies, we identified some brain regions that consistently come up, and they are surprisingly not very different from what we see with exercise research," said University of Illinois kinesiology and community health professor Neha Gothe, who led the research with Wayne State University psychology professor Jessica Damoiseaux.

"For example, we see increases in the volume of the hippocampus with yoga practice," Gothe said. Many studies looking at the brain effects of aerobic exercise have shown a similar increase in hippocampus size over time, she said.

The hippocampus is involved in memory processing and is known to shrink with age, Gothe said. "It is also the structure that is first affected in dementia and Alzheimer's disease."

Though many of the studies are exploratory and not conclusive, the research points to other important brain changes associated with regular yoga practice, Damoiseaux said. The amygdala, a brain structure that contributes to emotional regulation, tends to be larger in yoga practitioners than in their peers who do not practice yoga. The prefrontal cortex, cingulate cortex and brain networks such as the default mode network also tend to be larger or more efficient in those who regularly practice yoga.

"The prefrontal cortex, a brain region just behind the forehead, is essential to planning, decision-making, multitasking, thinking about your options and picking the right option," Damoiseaux said. "The default mode network is a set of brain regions involved in thinking about the self, planning and memory."

Like the amygdala, the cingulate cortex is part of the limbic system, a circuit of structures that plays a key role in emotional regulation, learning and memory, she said.

The studies also find that the brain changes seen in individuals practicing yoga are associated with better performance on cognitive tests or measures of emotional regulation.

The discovery that yoga may have similar effects on the brain to aerobic exercise is intriguing and warrants more study, Gothe said.

"Yoga is not aerobic in nature, so there must be other mechanisms leading to these brain changes," she said. "So far, we don't have the evidence to identify what those mechanisms are."

She suspects that enhancing emotional regulation is a key to yoga's positive effects on the brain. Studies link stress in humans and animals to shrinkage of the hippocampus and poorer performance on tests of memory, for example, she said.

"In one of my previous studies, we were looking at how yoga changes the cortisol stress response," Gothe said. "We found that those who had done yoga for eight weeks had an attenuated cortisol response to stress that was associated with better performance on tests of decision-making, task-switching and attention."

Yoga helps people with or without anxiety disorders manage their stress, Gothe said.

"The practice of yoga helps improve emotional regulation to reduce stress, anxiety and depression," she said. "And that seems to improve brain functioning."

The researchers say there is a need for more - and more rigorous - research into yoga's effects on the brain. They recommend large intervention studies that engage participants in yoga for months, match yoga groups with active control groups, and measure changes in the brain and performance on cognitive tests using standard approaches that allow for easy comparisons with other types of exercise.

"The science is pointing to yoga being beneficial for healthy brain function, but we need more rigorous and well-controlled intervention studies to confirm these initial findings," Damoiseaux said.

Leading scholars and publishers from The Ottawa Hospital's Centre for Journalology, the University of Ottawa's Telfer School of Management, and other institutions from around the world have agreed on a consensus definition of predatory publishing.

Led by Drs. Agnes Grudniewicz, David Moher, Kelly Cobey, and Manoj Lalu, their commentary was published in Nature.

Predatory journals are a global threat to quality science that was largely unknown a decade ago. There are now an estimated 8,000 predatory journals collectively publishing more than 400,000 research studies each year.

One of the challenges of solving this problem was that there was no agreed-upon definition of predatory publications-- until now.

At a recent international meeting in Ottawa, the team of experts reached this consensus definition: "Predatory journals and publishers are entities that prioritize self-interest at the expense of scholarship and are characterized by false or misleading information, deviation from best editorial and publication practices, a lack of transparency, and/or the use of aggressive and indiscriminate solicitation practices."

This definition will let researchers track predatory publishing, and develop educational resources and interventions to help fight this growing problem.

LAWRENCE -- If you're prone to depression, this holiday season you might want to say "bah humbug" to offers of sugar plum pudding, caramel corn and chocolate babka.

A new study from a team of clinical psychologists at the University of Kansas suggests eating added sugars - common in so many holiday foods - can trigger metabolic, inflammatory and neurobiological processes tied to depressive illness. The work is published in the journal Medical Hypotheses.

Coupled with dwindling light in wintertime and corresponding changes in sleep patterns, high sugar consumption could result in a "perfect storm" that adversely affects mental health, according to the researchers.

"For many people, reduced sunlight exposure during the winter will throw off circadian rhythms, disrupting healthy sleep and pushing five to 10% of the population into a full-blown episode of clinical depression," said Stephen Ilardi, KU associate professor of clinical psychology.

Ilardi, who coauthored the study with KU graduate students Daniel Reis (lead author), Michael Namekata, Erik Wing and Carina Fowler (now of Duke University), said these symptoms of "winter-onset depression" could prompt people to consume more sweets.

"One common characteristic of winter-onset depression is craving sugar," he said. "So, we've got up to 30% of the population suffering from at least some symptoms of winter-onset depression, causing them to crave carbs - and now they're constantly confronted with holiday sweets."

Ilardi said avoidance of added dietary sugar might be especially challenging because sugar offers an initial mood boost, leading some with depressive illness to seek its temporary emotional lift.

"When we consume sweets, they act like a drug," said the KU researcher, who also is author of "The Depression Cure" (First De Capo Press, 2009). "They have an immediate mood-elevating effect, but in high doses they can also have a paradoxical, pernicious longer-term consequence of making mood worse, reducing well-being, elevating inflammation and causing weight gain."

The investigators reached their conclusions by analyzing a wide range of research on the physiological and psychological effects of consuming added sugar, including the Women's Health Initiative Observational Study, the NIH-AARP Diet and Health Study, a study of Spanish university graduates, and studies of Australian and Chinese soda-drinkers.

Ilardi cautioned it might be appropriate to view added sugar, at high enough levels, as physically and psychologically harmful, akin to drinking a little too much liquor.

"We have pretty good evidence that one alcoholic drink a day is safe, and it might have beneficial effect for some people," he said. "Alcohol is basically pure calories, pure energy, non-nutritive and super toxic at high doses. Sugars are very similar. We're learning when it comes to depression, people who optimize their diet should provide all the nutrients the brain needs and mostly avoid these potential toxins."

The researchers found inflammation is the most important physiological effect of dietary sugar related to mental health and depressive disorder.

"A large subset of people with depression have high levels of systemic inflammation," said Ilardi. "When we think about inflammatory disease we think about things like diabetes and rheumatoid arthritis - diseases with a high level of systemic inflammation. We don't normally think about depression being in that category, but it turns out that it really is - not for everyone who's depressed, but for about half. We also know that inflammatory hormones can directly push the brain into a state of severe depression. So, an inflamed brain is typically a depressed brain. And added sugars have a pro-inflammatory effect on the body and brain."

Ilardi and his collaborators also identify sugar's impact on the microbiome as a potential contributor to depression.

"Our bodies host over 10 trillion microbes and many of them know how to hack into the brain," Ilardi said. "The symbiotic microbial species, the beneficial microbes, basically hack the brain to enhance our well-being. They want us to thrive so they can thrive. But there are also some opportunistic species that can be thought of as more purely parasitic - they don't have our best interest in mind at all. Many of those parasitic microbes thrive on added sugars, and they can produce chemicals that push the brain in a state of anxiety and stress and depression. They're also highly inflammatory."

Ilardi recommended a minimally processed diet rich in plant-based foods and Omega-3 fatty acids for optimal psychological benefit. As for sugar, the KU researcher recommended caution - not just during the holidays, but year-round.

"There's no one-size-fits-all approach to predicting exactly how any person's body will react to any given food at any given dose," Ilardi stated. "As a conservative guideline, based on our current state of knowledge, there could be some risk associated with high-dose sugar intake - probably anything above the American Heart Association guideline, which is 25 grams of added sugars per day."

Background

Optical switches will be important components in future photonic integrated circuits for ultrafast information processing. Optical switches control the on/off state or the direction of optical signals, and the switching speed depends on whether the optical signals are optically or electrically controlled. All-optical switches control optical signals with other optical signals, so they are unaffected by the RC time constant3, which limits the operation speed of electrical devices. Thus, it has been expected that all-optical switches will operate faster than electrically controlled ones. However, the switching energies of the previously reported all-optical switches are relatively large. This energy problem is a critical one for ultrafast information processing because optical components must be densely integrated in photonic circuits and the energy consumption of each device must be low. As shown in Fig. 1, high speed and low energy consumption have not been achieved simultaneously with the previously reported all-optical switches, and it had been assumed that a trade-off existed between the switching energy and switching time. In 2020, however, NTT overcame this trade-off and demonstrated all-optical switching with an extremely small driving energy by using a photonic crystal nanocavity with modest operating speed (tens of picoseconds). On the other hand, the trade-off still remained in the ultrafast switching regime (less than one picosecond), which is beyond the capability of electrical control.

Achievements

NTT and Tokyo Tech developed an all-optical switch operating in the ultrafast regime (less than one picosecond) with low energy consumption by combining an extremely small optical nanoscale waveguide based on plasmonics4 with graphene (Fig. 2a). The main points are as follows.

[1] Enhancement of absorption and nonlinear optical effect5 in graphene with plasmonic waveguides

To control optical signals with other optical signals, the properties of a material placed on the optical path must be changed with light, and the response time (i.e., the time in which this change occurs) is the one of the limitations on the switching time. Here, we employed graphene, which has an ultrafast nonlinear optical response. Graphene is not only a promising for its speed; it also has a large absorption coefficient6 over a broadband wavelength range. On the other hand, graphene is only one-atom thick, and the interaction with light is weak, which leads to long photonic devices and high energy consumption. In this work, we overcame this problem by strongly confining light within a nanoscale plasmonic waveguide.

We fabricated small plasmonic waveguides with a core size of 30 nm × 20 nm and loaded graphene on them by using NTT's nanofabrication technologies (Fig. 2b). The cross-sectional area of these plasmonic waveguides is about 1/100th that of "compact" silicon waveguides and 1/105 that of single-mode optical fibers. It was experimentally shown that the absorption coefficient of the graphene-loaded plasmonic waveguide is one order of magnitude smaller than that of graphene-loaded silicon waveguides. Moreover, the energy required for inducing nonlinear optical effects is four orders of magnitude smaller. These results show that compactness and low energy consumption can be achieved at the same time.

[2] Demonstration of ultrafast all-optical switching

The signal light is switched (on/off) with control light in all-optical switches (Fig. 3a). In our switch, the control light induces a nonlinear optical effect of graphene; i.e., it changes the degree of absorption by graphene. Figure 3b indicates that a switching time of 260 fs can be achieved with a switching energy of 35 fJ. The switching time is one order of magnitude shorter and the energy four orders of magnitude smaller than those of previous graphene-based devices. In addition, as shown in Fig. 1, the switching energy is the smallest value ever reported (1/100th of that previously reported) for any type of all-optical switch operating at less than one picosecond. Thus, we developed the first all-optical switch operating with a response time in the femtosecond range and an energy consumption in the femtojoule range. Moreover, the energy-time product, which is a measure of the trade-off mentioned above, was somewhat improved over that of the previous best device.

Outlook

NTT and Tokyo Tech are working on overcoming the limitations of electronics, such as on the operation speed and energy consumption, by integrating a dense photonic network into a processor chip. The all-optical switch operates much faster than an electrically controlled one and consumes less energy. We expect that it will be used in future photonic integrated circuits for ultrafast information processing. As well, the nanoscale waveguide of the switch is a superior platform for developing nanophotonic information processing devices incorporating nanowires and other two-dimensional materials. Moreover, we envision that our device can be used as a nonlinear activation function in optical neural networks. In the future, we will increase the performance of the all-optical switch, apply its technology to other photonic devices such as detectors, and examine the use of other nanomaterials.

Technical features

[1] Ultrafast nonlinear optical effect in graphene

We employed graphene for ultrafast operation. Monolayer graphene absorbs 2.3% of light over a broadband wavelength range (from visible to infrared), and this value means that graphene has a much larger absorption coefficient than that of conventional semiconductors. In addition, graphene shows saturable absorption7, a nonlinear optical effect, and its response time can be less than 100 fs. This ultrafast response originates from the very short relaxation times of graphene carriers. In our switch, a transmittance change induced by saturable absorption switches the on/off state, and the absorption saturates as a result of photo-excited carriers.

[2] Enhancement of the interaction between graphene and light by plasmonics

Graphene is a promising nonlinear optical material, but it is too thin to be used in optical devices. Here, we utilized a plasmonic waveguide with a height and width of a few tens of nanometers to enhance the interaction between graphene and light. Plasmonic waveguides strongly confine light--with a core width of only 30 nm and height of only 20 nm, the core area of our waveguide is as small as λ2/4000 (wavelength λ; in this case is 1550 nm). The interaction between graphene and light is weak when a conventional waveguide made of silicon is used; a numerical calculation gives an absorption coefficient of 0.089 dB/μm (2% per μm) for a graphene-loaded silicon waveguide with a core measuring 400 nm x 200 nm. This means that a device longer than 30 μm would be needed to obtain 50% absorption. On the other hand, the absorption coefficient for a plasmonic waveguide is estimated to be much higher, 2.0 dB/μm (37% per μm) for a core size of 30 nm x 20 nm, which enables the device length to be decreased. Furthermore, the light intensity at the position of the graphene is 310 times larger than that for a silicon waveguide because the plasmon waveguide core is much smaller. This enhancement significantly reduces the switching energy.

The above enhancement effects were observed in experiments. In particular, the experimentally obtained absorption coefficient for the plasmonic waveguide was 1.7 dB/μm. In addition, the obtained saturation energy was 12 fJ, which is four orders of magnitude smaller than that for graphene-loaded silicon waveguide. Because an increase in light intensity can be regarded as a reduction of the saturation energy in saturable absorption, this result means that the light intensity was enhanced by four orders of magnitude.

[3] Overcoming the drawbacks of plasmonics with mode converters

Although plasmonic waveguides strongly confine light, they have a large propagation loss, and directly coupling light to them is not easy because their waveguide cores are much smaller than the wavelength of light. Thus, we utilized the plasmonic waveguides only for the interaction with graphene and used highly efficient plasmonic mode converters to connect the plasmonic waveguides to conventional low-loss dielectric waveguides. An advanced fabrication technique is needed to make this mode converter; here, NTT developed a plasmonic mode converter connecting a deep-subwavelength plasmonic waveguide and a silicon waveguide in 2016. The plasmonic mode converters enable us to fully enjoy the merits of plasmonic waveguides and graphene in photonic integrated circuits.

When astronomers see something in the universe that at first glance seems like one-of-a-kind, it's bound to stir up a lot of excitement and attention. Enter comet 2I/Borisov. This mysterious visitor from the depths of space is the first identified comet to arrive here from another star. We don't know from where or when the comet started heading toward our Sun, but it won't hang around for long. The Sun's gravity is slightly deflecting its trajectory, but can't capture it because of the shape of its orbit and high velocity of about 100,000 miles per hour.

Telescopes around the world have been watching the fleeting visitor. NASA's Hubble Space Telescope has provided the sharpest views as the comet skirts by our Sun. Since October the space telescope has been following the comet like a sports photographer following horses speeding around a racetrack. Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is likely no more than about 3,200 feet across, about the length of nine football fields. Though comet Borisov is the first of its kind, no doubt there are many other comet vagabonds out there, plying the space between stars. Astronomers will eagerly be on the lookout for the next mysterious visitor from far beyond.

These two images, taken by Hubble, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.

Nov. 16, 2019, photo

The comet appears in front of a distant background spiral galaxy (2MASX J10500165-0152029). The galaxy's bright central core is smeared in the image because Hubble was tracking the comet. Comet Borisov was approximately 203 million miles from Earth in this exposure. Its tail of ejected dust streaks off to the upper right. The comet has been artificially colored blue to discriminate fine detail in the halo of dust, or coma, surrounding the central nucleus. It also helps to visually separate the comet from the background galaxy.

Dec. 9, 2019, photo

Hubble revisited the comet shortly after its closest approach to the Sun where it received maximum heating after spending most of its life in frigid interstellar space. The comet also reached a breathtaking maximum speed of about 100,000 miles per hour. Comet Borisov is 185 million miles from Earth in this photo, near the inner edge of the asteroid belt but below it. The nucleus, an agglomeration of ices and dust, is still too small to be resolved. The bright central portion is a coma made up of dust leaving the surface. The comet will make its closest approach to Earth in late December at a distance of 180 million miles.

"Hubble gives us the best upper limit of the size of comet Borisov's nucleus, which is the really important part of the comet," said David Jewitt, a UCLA professor of planetary science and astronomy, whose team has captured the best and sharpest look at this first confirmed interstellar comet. "Surprisingly, our Hubble images show that its nucleus is more than 15 times smaller than earlier investigations suggested it might be. Our Hubble images show that the radius is smaller than half a kilometer. Knowing the size is potentially useful for beginning to estimate how common such objects may be in the solar system and our galaxy. Borisov is the first known interstellar comet, and we would like to learn how many others there are."

Crimean amateur astronomer Gennady Borisov discovered the comet on Aug. 30, 2019, and reported the position measurements to the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts. The Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California, working with the Minor Planet Center, computed an orbit for the comet, which shows that it came from elsewhere in our Milky Way galaxy, point of origin unknown.

Nevertheless, observations by numerous telescopes show that the comet's chemical composition is similar to the comets found inside our solar system, providing evidence that comets also form around other stars. By the middle of 2020 the comet will have already zoomed past Jupiter's distance of 500 million miles on its way back into the frozen abyss of interstellar space.

A new image from NASA's Hubble Space Telescope provides important new details about the first interstellar comet astronomers have seen in our solar system.

The comet, called Comet 2I/Borisov (the "I" stands for interstellar), was spotted near a spiral galaxy known as 2MASX J10500165-0152029. It was approximately 203 million miles from Earth when the image was taken on Nov. 16.

"Data from the Hubble Space Telescope give us the best measure of the size of comet 2I/Borisov's nucleus, which is the really important part of the comet," said David Jewitt, a UCLA professor of planetary science and astronomy who analyzed and interpreted the data from the new image.

Jewitt collaborated on the new analysis with colleagues from the University of Hawaii, Germany's Max Planck Institute for Solar System Research, the Space Telescope Science Institute in Baltimore and Johns Hopkins University's Applied Physics Laboratory. The scientists were surprised to learn that the nucleus has a radius measuring only about half of a kilometer -- or less than one-fifteenth the size that earlier investigations suggested it might be.

"That is important because knowing its size helps us to determine the total number, and mass, of other similar objects in the solar system and the Milky Way," Jewitt said. "2I/Borisov is the first known interstellar comet, and we would like to learn how many others there are."

The comet is traveling at a breathtaking speed of 110,000 miles per hour -- one of the fastest comets ever seen, Jewitt said. More commonly, comets travel at about half that speed.

Crimean astronomer Gennady Borisov discovered the comet on Aug. 30, using a telescope he built. Based on precise measurements of its changing position, the International Astronomical Union's Minor Planet Center calculated a likely orbit for the comet, which shows that it came from elsewhere in the galaxy. Jewitt said its precise point of origin is unknown.

A second Hubble Space Telescope image of the comet, taken on Dec. 9, shows the comet even closer to Earth, approximately 185 million miles from Earth, he said.

Comets are icy bodies thought to be fragments left behind when planets form in the outer parts of planetary systems.

Observations by numerous telescopes show that the comet's chemical composition is similar to that of comets previously observed in our solar system, which provides evidence that comets also form around other stars, Jewitt said. By mid-2020, the comet will have zoomed past Jupiter on its way back into interstellar space, where it will drift for billions of years, Jewitt said.

New research suggests that, when two people must work together on a physical task despite conflicting goals, the amount of information available about each other's actions influences how quickly and optimally they learn to collaborate. Vinil Chackochan and Vittorio Sanguineti of the University of Genoa, Italy, present these findings in PLOS Computational Biology.

Most previous research into humans' ability to coordinate actions with others has addressed situations in which two people share a common goal, such as transporting a load or operating a tool. Much more often, people's goals conflict, and they must figure out how to collaborate. However, few studies have explored such situations.

For the new study, Chackochan and Sanguineti designed an experimental task in which two participants are assigned to perform different, competing sets of movements using the same mechanical apparatus at the same time. They also used Bayesian statistics and differential game theory to design a computational model that simulates similar partner situations.

Analysis of the experimental results and simulations revealed that, when one has more information about how a partner reacts to one's actions, collaboration is achieved more quickly, and one tends to develop optimal interaction strategies similar to those predicted by game theory. In contrast, with less information about one's partner, a person develops strategies that minimize the need for that information.

The findings provide new insights on the minimal computational machinery needed for stable physical collaboration. Understanding the mechanisms that underlie these kinds of human-human interactions could aid development of robots that can interact with people in a more natural, human-like fashion.

"Game theory has had a huge impact in many fields, including economics, political science, linguistics, operations research, and more," Chackochan says. "Application of game theory in human joint action may have far-reaching potential, especially in the area of human-robot interaction."

Next, the researchers plan to explore how people achieve and represent knowledge about a partner's ongoing actions and goals. They also aim to work towards development of a bio-inspired virtual agent with built-in collaborative capabilities.

London, UK: A recent study published in the journal Cephalalgia, the official journal of the International Headache Society, highlights an overlooked relationship between migraine and exercise. The study, entitled “Anxiety sensitivity and intentional avoidance of physical activity in women with probable migraine”, was led by Samantha G Farris, from Rutgers, Department of Psychology, the State University of New Jersey, NJ, USA.

Migraine affects around 10-15% of the population around the globe, and among its most common diagnosis criteria include a throbbing, unilateral head pain, hypersensitivity to lights, sounds, odors, and aggravation by activity. Although regular aerobic exercise has been strongly recommended by clinicians as an adjuvant option for migraine prevention, for up to 1/3 of patients, physical exercise can be a trigger of migraine attacks, thus, it can instead be avoided as a strategy to manage migraine. As observed with other pain conditions, anxiety sensitivity, which refers to one’s fear of experiencing anxiety arousal due to harmful physical, cognitive and socially-observable consequences, may be related to PA avoidance in migraine patients. This seems to be the true especially with vigorous PA, as this exercise intensity is perceived as potentially triggering or worsening of migraine attacks.

In this study, the researchers assessed 100 women with probable migraine, who filled an online survey covering anxiety sensitivity scores, intentional avoidance of moderate and vigorous physical activity (PA) in the past month, which was based on the Global Physical Activity Questionnaire (GPAQ), as well as the self-rated perception (0-100%) that PA would trigger a migraine attack and worse migraine symptoms.

The results showed that increased anxiety sensitivity scores associated with PA avoidance of both moderate and vigorous intensities. One-point increase in the anxiety sensitivity scale resulted in up to 5% increase in the odds for avoiding PA. Concerns about the physical consequences of bodily sensations (e.g. difficulty breathing) associated with a 7.5-fold higher odds for avoiding vigorous PA, while cognitive consequences of bodily sensations (e.g. inability to concentrate), which is thought to reflect headache-related disability, associated with a 5.2-fold higher odds for avoiding moderate PA. Anxiety sensitivity scores positively associated with stronger expectations of vigorous-intensity PA as a triggering and worsening factor for migraine.

This study revealed a relevant but overlooked aspect of migraine. Migraine is a highly prevalent and disabling neurological disorder, in which regular PA is part of current non-pharmacological treatment recommendations. As pointed out by the authors “Patients with migraine and elevated anxiety sensitivity could benefit from tailored, multi-component intervention, ideally including: Psychoeducation about the positive effect of PA on migraine and the detrimental effect of avoidance, feedback about the perceived versus actual rates of PA in triggering/worsening migraine, and use of gradual exposure to facilitate desensitization to avoided of PA and related bodily sensations.”

In today's criminal justice system, a Play Station and iPhone are just as important pieces of evidence as eyewitness accounts. Yet, there isn't a strong understanding as to how police officers identify digital evidence - everything from a laptop to a smart television - in the field.

Thomas Holt, professor of criminal justice at Michigan State University, is among the first researchers to capture how well police officers recognize digital evidence, as well as what to do with it.

"Digital evidence isn't part of the core police academy training, which is the baseline training all police recruits have when first going into the field," Holt said. "Since this training isn't consistently provided to them, how well would they recognize these critical pieces of evidence?"

The study - published in Policing: An International Journal - is based off a survey Holt conducted of 258 active state troopers and officers in the field. Holt gave the police a crime scene scenario in which they responded to a domestic violence call. From there, the police answered how they would respond and collect specific evidence on the crime scene.

Here are Holt's key findings:

1) Most - but not all - officers know who's the expert to call for support.

70% of the respondents said that they should contact the district prosecutor's office to ask what to do in a specific crime incident.

88% of officers said they knew who in that office is the right person.

"We can see that there's fairly consistent messaging around who to call in the event of a question," Holt said. "With digital evidence, it's difficult to know what to seize, or how to interact with it in a way that won't affect the information it holds. It's critical that all officers are aware of who the expert is to guide them in a delicate crime scene."

2) Not all officers know exactly what to look for.

76% said digital evidence could be anywhere in the scene.

43% said either on the wingspan of the suspect and victim or on the suspects or victim's person.

"We found that those who were familiar with digital evidence and seizing procedures were more likely to have responded recently to a scene where digital evidence was present," Holt said. "One big takeaway for us is that situational experience can help break down barriers and improve how police understand what to look for and where."

3) In the age of tech and smart homes, infinite pieces of evidence lay around the scene.

50% said to immediately seize all electronic items

91% said to secure mobile devices

90% said to secure any laptops

89% said to secure media storage devices

70% said to secure Amazon Echo/smart speaker

41% said to take the television

"There's a greater degree of recognition of what to do in the scene than I would have thought, like grabbing the Echo, the router or the TV," Holt said. "It's a very positive sign to see police knowing that storage devices are of great importance because any crimes that involve some sort of online activity or transactions - such as cyber security, child pornography or baking - could have evidence."

Holt explained that seeing degrees of digital evidence recognition - and it not varying across different age groups - is a positive sign, but there's work to be done.

"Our hope is that our research acts as baseline information for state agencies across the country," Holt said. "The huge takeaway or suggestion would be increasing training and awareness. We want them to start asking how well they train cadets to recognize devices in the field, what to do with it and how to improve as technology advances."

The brain determines when it is time to feed - but how does it know? Findings from St. Jude Children's Research Hospital provide new understanding of how the brain orchestrates this process. Skeletal muscle, like other tissues, communicates with the brain to convey information about nutritional status. The researchers showed that manipulating this mechanism influences food seeking and feeding in fruit flies. This work was published online today in Genes & Development.

Tissues like adipose, intestine and liver signal to the brain through hormones that regulate feeding behavior. Skeletal muscle makes up 40% of the human body and has high energy and nutrient demands. However, until now scientists did not appreciate how skeletal muscle can similarly communicate with the brain through signaling factors called myokines.

"Until now, the brain has been the least-studied target of myokine activity," said corresponding author Fabio Demontis, Ph.D., of the St. Jude Department of Developmental Neurobiology. "There are many myokines that act on other tissues, but their roles in signaling to the brain have been largely unexplored."

The molecular key to muscle-brain communication

To better understand how skeletal muscle communicates with the brain regarding feeding behavior, the researchers looked at the myokine Dpp in fruit flies. Dpp is the fruit fly equivalent of the BMP2 and BMP4 signaling factors in humans.

Scientists previously thought that Dpp only transmits signals at short distances. However, the researchers showed that fluorescently tagged Dpp travels long distances from the flight muscles of fruit flies to the brain. Furthermore, the researchers found that reducing Dpp levels promoted feeding and foraging behavior in fruit flies. Conversely, increasing Dpp levels reduced foraging and feeding.

A link between Dpp, dopamine and feeding initiation

The researchers also found that muscle-derived Dpp regulates the levels of brain tyrosine hydroxylase, an enzyme key to the synthesis of the neurotransmitter dopamine. Among a number of other roles, dopamine has previously been linked to feeding behavior.

The researchers found that lowering Dpp levels in muscle led to higher levels of dopamine in the brain and increased feeding. Conversely flies with higher Dpp levels in muscle had lower levels of brain dopamine and were less likely to seek food. The researchers also found that modulation of dopamine synthesis in the brain is key to the regulation of feeding by muscle-derived Dpp.

"Dpp is doing more than anyone thought it was. Beyond feeding behavior, endocrine Dpp signaling could be regulating a number of other tissue and systemic functions, including disease processes that involve dopaminergic neurons, " Demontis said. "And because Dpp has comparable proteins in humans, it may be relevant to feeding behavior and metabolic diseases in higher organisms."

(SACRAMENTO) -- Stronger comprehensive background check (CBC) policies enacted 2014 in Washington and 2015 in Oregon require private gun sellers to conduct background checks before selling firearms.

But have these newly enacted laws resulted in more background checks for private-party sales - the major source of guns for persons who commit crimes and are prohibited from owning them?

A study by the UC Davis Violence Prevention Research Program (VPRP) published Nov. 27 in Injury Epidemiology assessed changes in rates of background checks in Washington and Oregon from January 1999 through December 2018. They tracked monthly counts from the Federal Bureau of Investigation's National Instant Criminal Background Check System and compared them with synthetic controls created from 28 states that did not implement CBC policies during the study period.

The researchers found CBC policies were associated with an 18% increase in pre-firearm-sale checks in Oregon and a 4% increase in Washington state. They attribute the different rates between the two states to variation in the proportion of private party firearm sales, compliance with the new law among private gun sellers and the lack of mechanisms to measure enforcement of the laws.

"Washington's increase in private-party checks after its CBS policy took effect suggests a gradual adaptation to the new law by private gun sellers," said Alvaro Castillo-Carniglia, first author of the study who conducted the research as a VPRP scholar. "But firearm transactions coded as 'private' accounted for less than 5% of total background checks in the state, which is a very small proportion compared to national estimates."

In states without CBC policies, approximately 57% of private party transfers occur without background checks. In states with CBC policies, these private party transfers without checks decrease to 26%.

To fully determine the effects of CBC policies, the authors say they need more data and to assess changes in rates over a longer period of time.

Philadelphia, December 12, 2019 - High blood pressure in the lungs, known as pulmonary arterial hypertension (PAH), is a potentially fatal disease caused by obstruction of blood flow in the lungs. A new study in The American Journal of Pathology, published by Elsevier, sheds light on the pathology underlying PAH and shows that dofetilide, an FDA-approved KV11.1 channel blocker for the treatment of cardiac arrhythmias (brand name: Tikosyn), may be used for treatment of PAH.

Kv11.1 potassium selective channels are recognized for their function in the heart. Despite the importance of Kv11.1 channels for many physiological processes, their expression and function in pulmonary vasculature and potential role in PAH- and chronic obstructive pulmonary disease (COPD)-associated vascular remodeling had not been investigated.

Investigators examined lung tissue from patients with COPD and rats with experimentally-induced PAH. "Our study suggests that Kv11.1 channel blockers may have therapeutic potential for treatment of PAH. Specifically, we have shown that dofetilide, which is already FDA-approved as an antiarrhythmic and therefore has passed all of the drug safety requirements, can be considered for repurposing for treatment of patients with PAH," explained Tinatin I. Brelidze, PhD, assistant professor of pharmacology in the Department of Pharmacology and Physiology at Georgetown University Medical Center, Washington, DC, USA.

Researchers observed that Kv11.1 potassium selective channels are expressed in lungs and blocking these channels with dofetilide inhibits PAH associated with vascular remodeling. In control rats, Kv11.1 channels were expressed in the smooth muscle cell (SMC) layer of large diameter pulmonary arteries (PAs), but not in the SMCs of small diameter PAs (less than 100 μm). In rats with experimentally-induced PAH, the expression of Kv11.1 channels increased and the channels were found in both small and large PAs. The PA walls thickened as they became more muscular, and the lumens shrank.

When rats with PAH were treated with dofetilide, there was no evidence of the typical pathological changes in the vasculature associated with PAH. Dofetilide increased lumen diameter and decreased PA wall thickness to levels seen in the control rats without PAH.

In healthy human lung tissue, Kv11.1 channels were present only in the walls of large-diameter PAs. Lung tissue from patients with COPD showed collapse of alveoli, mild edema of the arterial walls, and fibrosis and thickening of PA walls. Kv11.1 channels were found in the walls of both large and small PAs, similar to that reported in rats with PAH.

Kv11.1 potassium channels are voltage-activated potassium channels that are expressed in many tissues and organs of the body. In the heart, Kv11.1 potassium channels help to repolarize cardiac action potentials to maintain proper heart rhythm whereas, in the brain, Kv11.1 channels regulate neuronal excitability. Inhibition of Kv11.1 channels also likely decreases the proliferation of cancer cells. "We hypothesize that similar to cancer, enlargement of SMCs in PAH is associated with the overexpression of Kv11.1 channels," noted Dr. Brelidze.

Since there is extensive clinical experience with dofetilide for cardiac arrhythmias and it has passed all drug safety requirements, the investigators suggest it merits consideration as a potential treatment for patients with PAH.