New shape-changing 4D materials hold promise for morphodynamic tissue engineering

Shape-changing scaffold for tissue engineering

UNIVERSITY OF ILLINOIS AT CHICAGO

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IMAGE: THE 4D MATERIAL CHANGES SHAPE IN RESPONSE TO WATER. THE GREY SIDE OF THE MATERIAL IN THE IMAGE ABSORBS WATER FASTER THAN THE BLUE SIDE, CAUSING IT TO BEND INTO... view more 

CREDIT: YU BIN LEE

New hydrogel-based materials that can change shape in response to psychological stimuli, such as water, could be the next generation of materials used to bioengineer tissues and organs, according to a team of researchers at the University of Illinois Chicago.

In a new paper published in the journal Advanced Functional Materials, the research team -- led by Eben Alsberg, the Richard and Loan Hill Professor of Biomedical Engineering -- that developed the substances show that the unique materials can curl into tubes in response to water, making the materials good candidates for bioengineering blood vessels or other tubular structures.

In nature, embryonic development and tissue healing often involve a high concentration of cells and complex architectural and organizational changes that ultimately give rise to final tissue morphology and structure.

For tissue engineering, traditional techniques have involved, for example, culturing biodegradable polymer scaffolds with cells in biochambers filled with liquid nutrients that keep the cells alive. Over time, when provided with appropriate signals, the cells multiply in number and produce new tissue that takes on the shape of the scaffold as the scaffold degrades. For example, a scaffold in the shape of an ear seeded with cells capable of producing cartilage and skin tissue may eventually become a transplantable ear.

However, a geometrically static scaffold cannot enable the formation of tissues that dynamically change shape over time or facilitate interactions with neighboring tissues that change shape. A high density of cells is also typically not used and/or supported by the scaffolds.

"Using a high density of cells can be advantageous in tissue engineering as this enables increased cell-cell interactions that can promote tissue development," said Alsberg, who also is professor of orthopaedics, pharmacology and mechanical and industrial engineering at UIC.

Enter 4D materials, which are like 3D materials, but they change shape when they are exposed to specific environmental cues, such as light or water. These materials have been eyed by biomedical engineers as potential new structural substrates for tissue engineering, but most currently available 4D materials are not biodegradable or compatible with cells.

To take advantage of the promise of 4D materials for bioengineering applications, Alsberg and colleagues developed novel 4D materials based on gelatin-like hydrogels that change shape over time in response to the addition of water and are cell-compatible and biodegradable, making them excellent candidates for advanced tissue engineering. The hydrogels also support very high cell densities, so they can be heavily seeded with cells.

In the paper, the researchers describe how exposure to water causes the hydrogel scaffolds to swell as the water is absorbed. The amount of swelling can be tuned by, for example, changing aspects of the hydrogel material such as its degradation rate or the concentration of cross-linked polymers -- strands of protein or polysaccharide in this case -- that comprise the hydrogels. The higher the polymer concentration and crosslinking, the less and more slowly a given hydrogel will absorb water to induce a change in shape.

The researchers found that by layering hydrogels with different properties like a stack of paper, the difference in water absorption between the layers will cause the hydrogel stack to bend into a 'C' shaped conformation. If the stack bends enough, a tubular shape is formed, which resembles structures like blood vessels and other tubular organs.

They also found that it is possible to calibrate the system to control the timing and the extent of shape change that occurred. The researchers were able to embed bone marrow stem cells into the hydrogel at very high density -- the highest density of cells ever recorded for 4D materials -- and keep them alive, a significant advance in bioengineering that has practical applications.

In the paper, the researchers described how the shape-changing cell-laden hydrogel could be induced to become bone- and cartilage-like tissues. 4D bioprinting of this hydrogel was also implemented to obtain unique configurations to achieve more complex 4D architectures.

"Using our bilayer hydrogels, we can not only control how much bending the material undergoes and its temporal progression, but because the hydrogels can support high cell densities, they more closely mimic how many tissues form or heal naturally," said Yu Bin Lee, a biomedical engineering postdoctoral researcher and first author on the paper. "This system holds promise for tissue engineering, but may also be used to study the biological processes involved in early development."

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UIC's Oju Jeon, Sang Jin Lee, Aixiang Ding and Derrick Wells are co-authors on the paper.

This research was supported by grants from the National Institutes of Health's National Institute of Arthritis And Musculoskeletal and Skin Diseases (R01AR069564, R01AR066193) and the National Institute of Biomedical Imaging and Bioengineering (R01EB023907).

Bearded seals are loud -- but not loud enough

Vocal threshold may hamper survival of this Arctic species

CORNELL UNIVERSITY

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IMAGE: BEARDED SEAL ON ICE view more 

CREDIT: MICHAEL CAMERON, NOAA

Ithaca, NY-- During mating season, male bearded seals make loud calls to attract a mate--even their "quiet" call could still be as ear-rattling as a chainsaw. Bearded seals have to be loud to be heard over the cacophony of their equally loud brethren. And, increasingly, the noise humans make is adding to the underwater din and could have serious consequences. A study conducted by the Cornell Lab of Ornithology's Center for Conservation Bioacoustics (CCB) aims to understand how resilient bearded seals can be to changes in ambient underwater noise. The results are published in Proceedings of the Royal Society: Biological Science.

"We wanted to know whether bearded seals would call louder when their habitat grew noisy from natural sound sources," says CCB postdoctoral research associate Michelle Fournet who led the study. "The goal was to determine if there was a 'noise threshold' beyond which seals either couldn't-or wouldn't-call any louder in order to heard. By identifying this naturally occurring threshold, we can make conservation recommendations about how loud is too loud for human activities.'

From spring through early summer, the under-ice habitat near Utqiagvik, Alaska, is flooded with the vocalizations of male bearded seals--a sound that can be best described as "otherworldly." These elaborate vocalizations are essential for bearded seal reproduction, but in the rapidly changing Arctic soundscape, where noise from industrial activities is predicted to dramatically increase in the next 15 years, bearded seals may need to adjust their calling behavior if they are going to be heard above the noise generated by ships and commercial activities. But the bearded seals can only do so much.

Fournet and colleagues listened to thousands of recorded bearded seal vocalizations from Arctic Alaska spanning a two-year period. Each call was carefully measured and compared to the concurrent ambient noise conditions. What they found is that bearded seals do call louder as their underwater acoustic habitat gets noisier, but there is an upper limit to this behavior. As expected, when ambient noise gets too high, bearded seals are no longer able to compensate in order to be heard. As a result, as ambient noise conditions increase, the distance over which individuals can be detected goes down.

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Bearded seal

Bearded seal [audio] | EurekAlert! Science News

"Given that these are reproductive calls, it is likely that the seals are already calling as close to as loudly as possible-the males very much want to be heard by the females," Fournet says. "So, it is unsurprising that there is an upper limit. I'm grateful that we have been able to identify that limit so we can make responsible management choices moving forward."

While this work has intrinsic conservation value, a major impetus for pursuing this research is the value of bearded seals-or ugruk in the Inupiaq language-to Alaska Native communities in the high Arctic. Bearded seals are at the center of subsistence and cultural activities in Inupiaq communities. Threats to bearded seals are by extension threats to the communities that rely on them.

"This work never would have happened without the insight and guidance of Arctic communities," Fournet says. "It was their energy that led the Cornell Lab to place hydrophones in the water. It is our job to continue listening."

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Reference: Michelle E. H. Fournet, Margherita Silvestri, Christopher W. Clark, Holger Klinck, and Aaron N. Rice. Limited vocal compensation for elevated ambient noise in bearded seals: implications for an industrializing Arctic Ocean. Proceedings of the Royal Society B. February 2021.

Study finds human-caused North Atlantic right whale deaths are being undercounted

As recent sightings of entangled whales raise alarm, scientists say annual counts of right whale carcasses do a poor job of indicating true death toll

NEW ENGLAND AQUARIUM

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IMAGE: CATALOG #3522 SWIMS OFF THE COAST OF GEORGIA IN 2006 WITH FRESH PROPELLER CUTS ON HIS BACK. HE WAS NEVER SEEN AGAIN AND IS PRESUMED DEAD DUE TO THESE INJURIES. view more 

CREDIT: NEW ENGLAND AQUARIUM, COLLECTED UNDER NOAA PERMIT #655-1652-01

A study co-authored by scientists at the New England Aquarium has found that known deaths of critically endangered North Atlantic right whales represent a fraction of the true death toll. This comes as the death of a calf and recent sightings of entangled right whales off the southeastern United States raise alarm.

The study, published this month in Conservation Science and Practice, analyzed cryptic mortality of right whales. Cryptic mortality refers to deaths resulting from human activities that do not result in an observed carcass. The study's authors combined data on whale encounters, animal health, serious injuries, and necropsies from the North Atlantic Right Whale Consortium Identification Database curated by the New England Aquarium with the serious injury and mortality database held by the National Marine Fisheries Service. The scientists concluded that known deaths of the critically endangered species accounted for only 36% of all estimated death from 1990 to 2017.

"Our work has shown that 83% of identified right whales have been entangled one or more times in fishing gear, and an increasing number of these events result in severe injuries or complex entanglements that the whales initially survive. But we know their health becomes compromised and they eventually succumb and sink upon death," said Amy Knowlton, senior scientist with the Aquarium's Anderson Cabot Center for Ocean Life.

The study--led by Richard Pace and Rob Williams and co-authored by Knowlton, New England Aquarium Associate Scientist Heather Pettis, and Aquarium Emeritus Scientist Scott Kraus--determined that several factors interact to cause undercounting of human-caused mortalities of marine mammals. First, in order for a human-caused mortality to be determined, a whale carcass must float or strand, be detected before decomposition or scavenging occurs, be evaluated to determine cause of death, and then have that result reported. In the absence of any of these steps, information about the cause of mortality can easily be lost.

Additionally, a number of right whales have been observed entangled or injured from vessel strikes and never seen again. This suggests they died and their carcasses were not discovered.

"We have long known that the number of detected right whale carcasses does not align with the number of whales that disappear from the sightings records," Pettis said. "Since 2013 alone, we have documented 40 individual right whales seen with severe injuries resulting from vessel strikes and entanglements that disappeared following their injury. This study allowed us to quantify just how underrepresented true right whale mortalities are when we rely on observed carcasses alone."

The estimated population number for North Atlantic right whales stands at just over 350 whales. Right whales are one of the most endangered large whale species in the world, facing serious ongoing threats from vessels and fishing gear. Just in the past month, a right whale calf died in an apparent vessel strike and two right whales have been spotted entangled in fishing gear. A sport fishing boat hit and killed the calf in the calving grounds off the Florida coast on February 12. The calf was the first born to Infinity (Catalog #3230), who also suffered injuries consistent with a vessel strike. Catalog #1803, a 33-year-old male, was seen badly entangled off the coast of Georgia and Florida in mid-January, and on February 18, Cottontail (Catalog #3920) was sighted entangled and emaciated off the Florida coast. Cottontail, an 11-year-old male, was first seen entangled in southern New England last fall. In both cases, disentanglement efforts were not successful and these whales will likely die.

"These serious entanglements are preventable with regulatory changes and a commitment from the fishing industry and the U.S. and Canadian governments to do more to address this threat," said Knowlton.

For 40 years, the Aquarium's Right Whale Research Program has extensively studied this critically endangered species. Scientists focus on solutions-based work, collaborating with fishermen on new techniques to reduce deadly entanglements in fishing gear, facilitating communication across the maritime industry to reduce vessel strikes, and working with lawmakers locally, nationally, and internationally to develop science-based protections for the whales.

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UM scientists achieve breakthrough in culturing corals and sea anemones cells

UNIVERSITY OF MIAMI ROSENSTIEL SCHOOL OF MARINE & ATMOSPHERIC SCIENCE

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IMAGE: POCILLOPORA DAMICORNIS FROM SABOGA ISLAND, PANAMA GROWING IN THE CNIDARIAN IMMUNITY LAB AT THE ROSENSTIEL SCHOOL view more 

CREDIT: MIKE CONNELLY

MIAMI--Researchers have perfected the recipe for keeping sea anemone and coral cells alive in a petri dish for up to 12 days. The new study, led by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, has important applications to study everything from evolutionary biology to human health.

Cnidarians are emerging model organisms for cell and molecular biology research. Yet, successfully keeping their cells in a laboratory setting has proved challenging due to contamination from the many microorganisms that live within these marine organisms or because the whole tissue survive in a culture environment.

UM cell biologist Nikki Traylor-Knowles and her team used two emerging model organisms in developmental and evolutionary biology--the starlet sea anemone (Nematostella vectensis) and cauliflower coral (Pocillopora damicornis)--to find more successful way to grow these cell cultures in a laboratory setting.

James Nowotny, a recent UM graduate mentored by Traylor-Knowles at the time, tested 175 cell cultures from the two organisms and found that their cells can survive for on average 12 days if they receive an antibiotic treatment before being cultured.

"This is a real breakthrough," said Traylor Knowles, an assistant professor of marine biology and ecology at the UM Rosenstiel School. "We showed that if you treat the animals beforehand and prime their tissues, you will get a longer and more robust culture to study the cell biology of these organisms."

"This is the first time that individual cells from all tissues of coral or sea anemones were shown to survive in cell culture for over 12 days," said Nowotny, who is currently a graduate student at the University of Maryland.

There are over 9,000 species in the phylum Cnidaria, which includes jellyfish, sea anemones, corals, Hydra, and sea fans. Due to several special unique attributes such as radial symmetry, a stinging cell known as a nematocyte and two-dermal cell layer, there is growing interest in using these animals to study key aspects of animal development.

"We can also now grow coral cells and use them in experiments that will help improve our understanding of their health in a very targeted way," said Traylor-Knowles.

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The study, titled "Novel Methods to Establish Whole-Body Primary Cell Cultures for the Cnidarians Nematostella vectensis and Pocillopora damicornis," was published in the Feb. 18 issue of the journal Scientific Reports. The authors include: Nikki Traylor-Knowles, James Nowotny and Michael Connelly from the UM Rosenstiel School. The study was funded through the National Science Foundation (award # 1951826) and Revive and Restore Catalyst Science Fund.

New discoveries on the containment of COVID-19 finds travel bans are of limited value

NYU Tandon researchers join collaboration with Politecnico di Torino revealing that after spread, travel bans are of limited value in thwarting the spread of COVID-19

NYU TANDON SCHOOL OF ENGINEERING

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BROOKLYN, New York, Wednesday, February 24, 2021 - Travel bans have been key to efforts by many countries to control the spread of COVID-19. But new research aimed at providing a decision support system to Italian policy makers, recently published in the Journal of the Royal Society Interface, suggests that reducing individual activity (i.e., social distancing, closure of non-essential business, etc.) is far superior in controlling the dissemination of Sars-CoV-2, the virus that causes COVID-19.

The research, which has implications for the United States and other countries, found that limiting personal mobility through travel restrictions and similar tactics is effective only in the first phases of the epidemic, and reduces in proportion to the spread of infection across a population.

In the study, "Modelling and predicting the effect of social distancing and travel restrictions on COVID-19 spreading" the researchers, led by Alessandro Rizzo, visiting professor in the Office of Innovation at NYU Tandon and professor at the Politecnico di Torino, and Maurizio Porfiri Institute Professor of mechanical and aerospace, biomedical and civil and urban engineering at NYU Tandon and a member of the Center for Urban Science and Progress (CUSP), detail a data modeling framework for isolating the differential efficacy of different COVID-19 intervention policies. Since their method benefits from a low computational load (it can easily run on a personal computer), it can be a valuable decision support system to policy makers, toward the implementation of combined containment actions that can protect citizens' health, while avoiding total closures, with all their economic, social, and psychological consequences.

"While this project was focused specifically on Italy, the results are revelatory for virtually any country relying on travel restrictions to stem the spread of the pandemic. We look forward to using US data to tune the model and give specific answers to combat this delicate phase of the pandemic," said Porfiri.

Added Rizzo, "We are particularly satisfied with this model, as it provides very detailed answers even though it relies only on aggregated sources of data - a further guarantee of people's privacy."

The work includes a realistic representation of demographic data and travel patterns of both commuters and those taking long-distance trips, using only aggregated and publicly available data, without resorting to individual tracking devices. It follows upon a study on the spread of Covid-19 in New Rochelle, New York predicting the diffusion of COVID-19 in medium sized cities and provinces, published as the cover of Advanced Modeling and Simulations (Wiley),

The investigators, including Francesco Parino of Politecnico di Torino and Lorenzo Zino of the University of Groningen, The Netherlands, also found that selective lockdown policies, for example restriction only on the activity of the elderly, seems not to have a great effect on the overall transmission of the epidemic.

Deploying their algorithmic framework to model scenarios in which restrictions are lifted, discovered that restrictions on social activity must be gradually removed to avoid a second wave, while the timing and swiftness of removal of travel restrictions seem not to have a great effect on the transmission.

In view of the scarce resources and the inherent slowness of vaccination campaigns, the research group is now engaged in the use of the model to assess the effect of different vaccination policies, toward the definition of vaccination rollouts that will aim at providing an optimal outcome in spite of the limited resources in terms of vaccine doses and operators.

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The U.S. National Science Foundation (CMMI-1561134 and CMMI-2027990), Compagnia di San Paolo, MAECI ('Mac2Mic'), the European Research Council (ERC-CoG-771687), and The Netherlands Organisation for Scientific Research (NWO-vidi-14134) provided generous support for this research.

About the New York University Tandon School of Engineering

The NYU Tandon School of Engineering dates to 1854, the founding date for both the New York University School of Civil Engineering and Architecture and the Brooklyn Collegiate and Polytechnic Institute. A January 2014 merger created a comprehensive school of education and research in engineering and applied sciences as part of a global university, with close connections to engineering programs at NYU Abu Dhabi and NYU Shanghai. NYU Tandon is rooted in a vibrant tradition of entrepreneurship, intellectual curiosity, and innovative solutions to humanity's most pressing global challenges. Research at Tandon focuses on vital intersections between communications/IT, cybersecurity, and data science/AI/robotics systems and tools and critical areas of society that they influence, including emerging media, health, sustainability, and urban living. We believe diversity is integral to excellence, and are creating a vibrant, inclusive, and equitable environment for all of our students, faculty and staff. For more information, visit engineering.nyu.edu.

After Hurricane Irma, soundscape reveals resilient reef ecosystem

NORTH CAROLINA STATE UNIVERSITY

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A new study from North Carolina State University reveals that the soundscapes of coral reef ecosystems can recover quickly from severe weather events such as hurricanes. The work also demonstrates that non-invasive monitoring is an important tool in shedding further light on these key ecosystems.

Soundscape ecology is a relatively new way for researchers to keep tabs on a variety of habitats without direct interference. In underwater habitats like coral reefs, soundscapes allow continual monitoring of an ecosystem that is difficult to access. By deploying underwater microphones, or hydrophones, researchers can get an acoustic picture of the types of animals in the ecosystem, as well as their behavior patterns.

Kayelyn Simmons, a Ph.D. student at NC State, used soundscapes and underwater mapping to monitor two different reef sites in the Florida Keys from February to December 2017. She deployed and collected eight hydrophones every three months between the two sites: a pristine reef located at Eastern Sambo, and a fishing site located at Western Dry Rocks.

Hurricane Irma struck the Florida Keys as a Category 4 storm in September 2017. Simmons was able to retrieve two of the hydrophones - one from each site - in December. Unfortunately, the hydrophone retrieved from Western Dry Rocks had been compromised by the storm, rendering its post-storm data unusable.

"Prior to the hurricane, we were able to determine what the 'normal' sound patterns were in each habitat, so we knew what the baselines were in terms of species and behavior," Simmons says. "You can tell which species are present based on where their sounds are on the frequency band. Similarly, the amount of noise from each species can give you an idea of their numbers. So the soundscape is a good way to measure abundance and diversity."

Each study site had the same species present. For example, snapping shrimp, with their high frequency "Rice Krispies in milk" popping noises, were active in the periods between dusk and dawn; while grunts, grouper and snapper, with sounds in the lower frequency bands, were mainly active during the day. The hydrophones also captured spawning activity during the full moon.

Simmons analyzed the sound captured by the surviving Eastern Sambo hydrophone and discovered that even though the reef suffered physical damage from the hurricane, the residents and their activity levels began returning to normal approximately 24 to 48 hours after the storm passed.

"The acoustic energy exposure for the reef was as loud as a small boat circling in one spot for two weeks," Simmons says. "So we didn't record any fish noises during the four-day period that Irma came through due to acoustic masking from the storm. However, the snapping shrimp were back to pre-storm sound levels within 24 hours. The fish noises on the lower frequency were back within 72. And on the next full moon we heard normal spawning behavior.

"Overall, the research shows that the coral reef soundscape was resilient and able to recover from the storm quickly."

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The work appears in PLOS One and was supported by the Coral Reef Conservation Fund (grant NA18NOS4820113) and the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program (grant NFFM7320-19-01243). David Eggleston and Del Bohnenstiehl, both professors of marine, earth and atmospheric sciences at NC State, co-authored the work.

Note to editors: An abstract follows.

"Hurricane impacts on a coral reef soundscape"

DOI: 10.1371/journal.pone.0244599

Authors: Kayelyn Simmons, Dave Eggleston, Del Bohnenstiehl, North Carolina State University

Published: Feb. 24 in PLOS One

Abstract:

Soundscape ecology is an emerging field in both terrestrial and aquatic ecosystems, and provides a powerful approach for assessing habitat quality and the ecological response of sound producing species to natural and anthropogenic perturbations. Little is known of how underwater soundscapes respond during and after severe episodic disturbances, such as hurricanes. This study addresses the impacts of Hurricane Irma on the coral reef soundscape at two spur-and groove fore-reef sites within the Florida Keys USA, using passive acoustic data collected before and during the storm at Western Dry Rocks (WDR) and before, during and after the storm at Eastern Sambo (ESB). As the storm passed, the cumulative acoustic exposure near the seabed at these sites was comparable to a small vessel operating continuously overhead for 1-2 weeks. Before the storm, sound pressure levels (SPLs) showed a distinct pattern of low frequency diel variation and increased high frequency sound during crepuscular periods. The low frequency band was partitioned in two groups representative of soniferous reef fish, whereas the high frequency band represented snapping shrimp sound production. Daily daytime patterns in low frequency sound production largely persisted in the weeks following the hurricane. Crepuscular sound production by snapping shrimp was maintained post-hurricane with only a small shift (~1.5dB) in the level of daytime vs nighttime sound production for this high frequency band. This study suggests that on short time scales, temporal patterns in the coral reef soundscape were relatively resilient to acoustic energy exposure during the storm, as well as changes in the benthic habitat and environmental conditions resulting from hurricane damage.

Parker Solar Probe offers stunning view of Venus

NASA/GODDARD SPACE FLIGHT CENTER

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IMAGE: WHEN FLYING PAST VENUS IN JULY 2020, PARKER SOLAR PROBE'S WISPR INSTRUMENT, SHORT FOR WIDE-FIELD IMAGER FOR PARKER SOLAR PROBE, DETECTED A BRIGHT RIM AROUND THE EDGE OF THE PLANET... view more 

CREDIT: NASA/JOHNS HOPKINS APL/NAVAL RESEARCH LABORATORY/GUILLERMO STENBORG AND BRENDAN GALLAGHER

NASA's Parker Solar Probe captured stunning views of Venus during its close flyby of the planet in July 2020.

Though Parker Solar Probe's focus is the Sun, Venus plays a critical role in the mission: The spacecraft whips by Venus a total of seven times over the course of its seven-year mission, using the planet's gravity to bend the spacecraft's orbit. These Venus gravity assists allow Parker Solar Probe to fly closer and closer to the Sun on its mission to study the dynamics of the solar wind close to its source.

But -- along with the orbital dynamics -- these passes can also yield some unique and even unexpected views of the inner solar system. During the mission's third Venus gravity assist on July 11, 2020, the onboard Wide-field Imager for Parker Solar Probe, or WISPR, captured a striking image of the planet's nightside from 7,693 miles away.

WISPR is designed to take images of the solar corona and inner heliosphere in visible light, as well as images of the solar wind and its structures as they approach and fly by the spacecraft. At Venus, the camera detected a bright rim around the edge of the planet that may be nightglow -- light emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on the Venusian surface. The feature appears dark because of its lower temperature, about 85 degrees Fahrenheit (30 degrees Celsius) cooler than its surroundings.

That aspect of the image took the team by surprise, said Angelos Vourlidas, the WISPR project scientist from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, who coordinated a WISPR imaging campaign with Japan's Venus-orbiting Akatsuki mission. "WISPR is tailored and tested for visible light observations. We expected to see clouds, but the camera peered right through to the surface."

"WISPR effectively captured the thermal emission of the Venusian surface," said Brian Wood, an astrophysicist and WISPR team member from the U.S. Naval Research Laboratory in Washington, D.C. "It's very similar to images acquired by the Akatsuki spacecraft at near-infrared wavelengths."

This surprising observation sent the WISPR team back to the lab to measure the instrument's sensitivity to infrared light. If WISPR can indeed pick up near-infrared wavelengths of light, the unforeseen capability would provide new opportunities to study dust around the Sun and in the inner solar system. If it can't pick up extra infrared wavelengths, then these images -- showing signatures of features on Venus' surface -- may have revealed a previously unknown "window" through the Venusian atmosphere.

"Either way," Vourlidas said, "some exciting science opportunities await us."

For more insight into the July 2020 images, the WISPR team planned a set of similar observations of the Venusian nightside during Parker Solar Probe's latest Venus flyby on Feb. 20, 2021. Mission team scientists expect to receive and process that data for analysis by the end of April.

"We are really looking forward to these new images," said Javier Peralta, a planetary scientist from the Akatsuki team, who first suggested a Parker Solar Probe campaign with Akatsuki, which has been in orbiting Venus since 2015. "If WISPR can sense the thermal emission from the surface of Venus and nightglow -- most likely from oxygen -- at the limb of the planet, it can make valuable contributions to studies of the Venusian surface."

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Parker Solar Probe is part of NASA's Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency's Goddard Space Flight Center in Greenbelt, Maryland, for NASA's Science Mission Directorate in Washington. Johns Hopkins APL designed, built and operates the spacecraft.

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NASA's Parker Solar Probe had an up-close view of Venus when it flew by the planet in July 2020. Some of the features seen by scientists are labeled in this annotated image. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument.

CREDIT

NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher

Scientists link star-shredding event to origins of universe's highest-energy particles

NEW YORK UNIVERSITY

 VIDEO: AS THE STAR APPROACHES THE BLACK HOLE, THE ENORMOUS TIDAL FORCES STRETCH IT MORE AND MORE UNTIL IT IS FINALLY SHRED. HALF OF THE STELLAR DEBRIS IS FLUNG BACK INTO... view more 

CREDIT: DESY, SCIENCE COMMUNICATION LAB

A team of scientists has detected the presence of a high-energy neutrino--a particularly elusive particle--in the wake of a star's destruction as it is consumed by a black hole. This discovery, reported in the journal Nature Astronomy, sheds new light on the origins of Ultrahigh Energy Cosmic Rays--the highest energy particles in the Universe.

The work, which included researchers from more than two dozen institutions, including New York University and Germany's DESY research center, focused on neutrinos--subatomic particles that are produced on Earth only in powerful accelerators.

Neutrinos--as well as the process of their creation--are hard to detect, making their discovery, along with that of Ultrahigh Energy Cosmic Rays (UHECRs), noteworthy.

"The origin of cosmic high-energy neutrinos is unknown, primarily because they are notoriously hard to pin down," explains Sjoert van Velzen, one of the paper's lead authors and a postdoctoral fellow in NYU's Department of Physics at the time of the discovery. "This result would be only the second time high-energy neutrinos have been traced back to their source."

Previous research by van Velzen, now at the Netherlands' Leiden University, and NYU physicist Glennys Farrar, a co-author of the new Nature Astronomy paper, found some of the earliest evidence of black holes destroying stars in what are now known as Tidal Disruption Events (TDEs). These findings set the stage for determining if TDEs could be responsible for producing UHECRs.

The research reported in Nature Astronomy offered support for this conclusion.

Previously, the IceCube Neutrino Observatory, a National Science Foundation-backed detector located in the South Pole, reported the detection of a neutrino, whose path was later traced by the Zwicky Transient Facility at Caltech's Palomar Observatory.

Specifically, its measurements showed a spatial coincidence of a high-energy neutrino and light emitted after a TDE--a star consumed by a black hole.

"This suggests these star shredding events are powerful enough to accelerate high-energy particles," van Velzen explains.

"Discovering neutrinos associated with TDEs is a breakthrough in understanding the origin of the high-energy astrophysical neutrinos identified by the IceCube detector at the South Pole whose sources have so far been elusive," adds Farrar, who proposed in a 2009 paper that UHECRs could be accelerated in TDEs. "The neutrino-TDE coincidence also sheds light on a decades old problem: the origin of Ultrahigh Energy Cosmic Rays."

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The research was supported by grants from the National Science Foundation (CAREER grant 1454816, AAG grant 1616566, PIRE Grant 1545949, NSF grant AST-1518052)

DOI: 10.1038/s41550-020-01295-8

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After the supermassive black hole tore the star apart, roughly half of the star debris was flung back out into space, while the remainder formed a glowing accretion disc around the black hole. The system shone brightly across many wavelengths and is thought to have produced energetic, jet-like outflows perpendicular to the accretion disc. A central, powerful engine near the accretion disc spewed out these fast subatomic particles.

CREDIT

DESY, Science Communication Lab

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A view of the accretion disc around the supermassive black hole, with jet-like structures flowing away from the disc. The extreme mass of the black hole bends spacetime, allowing the far side of the accretion disc to be seen as an image above and below the black hole.

CREDIT

DESY, Science Communication Lab

Allergy season starts earlier each year due to climate change and pollen transport

Scientists in Munich study how pollen from far distances -- sometimes hundreds of kilometers away -- affects the length of allergy seasons in Germany

FRONTIERS

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IMAGE: GRASS POLLEN GRAINS UNDER LIGHT MICROSCOPE view more 

CREDIT: A. MENZEL AND Y. YUAN, TECHNICAL UNIVERSITY OF MUNICH

Allergy sufferers are no strangers to problems with pollen. But now - due to climate change - the pollen season is lasting longer and starting earlier than ever before, meaning more days of itchy eyes and runny noses. Warmer temperatures cause flowers to bloom earlier, while higher CO2 levels cause more pollen to be produced.

The effects of climate change on the pollen season have been studied at-length, and according to some scientists, has grown by as much as 20 days in the past 30 years, at least in the US and Canada. But one important element is often overlooked - "Pollen is meant to fly," says Dr Annette Menzel, Professor of ecoclimatology at the Technical University of Munich. "Transport phenomena have to be taken into account."

Along with her colleagues, she studied the transport of pollen in Bavaria, Germany, in order to better understand how the pollen season has changed over time. "The transport of pollen has important implications for the length, timing, and severity of the allergenic pollen season," says Dr Ye Yuan, a coauthor on the study.

Menzel and her team focused on Bavaria - a state in southeast Germany - and used six pollen monitoring stations scattered around the region to analyze data. Their results were recently published in Frontiers in Allergy. They found that certain species of pollen, such as from hazel shrubs and alder trees, advanced the start of their seasons by up to 2 days per year, over a period of 30 years (between 1987 and 2017). Other species, which tend to bloom later in the year, such as birch and ash trees, moved their seasons 0.5 days earlier on average each year, across that same time period.

Pollen can travel hundreds of kilometers and, with changing weather patterns and altered species distributions, it's possible that people are becoming exposed to "new" pollen species - meaning pollen that our bodies are unaccustomed to encountering each year.

While it can sometimes be difficult to differentiate between local and transported pollen, the researchers focused on pre-season transports. So, for example, if pollen from birch trees was present at the monitoring station, but local birch trees would not flower for at least another 10 days, that pollen was considered to be transported from far away.

"We were surprised that pre-season pollen transport is a quite common phenomenon being observed in two-thirds of the cases," says Menzel. As for why it's important to understand how much pollen is from far away, Yuan says that: "Especially for light-weight allergenic [pollen], long distance transport could seriously influence local human health."

By examining another element besides simple pollen concentration, scientists can delve deeper into how exactly the pollen season is being affected by climate change. For example, Menzel says that the pollen season may be even longer than estimated based on flowering observations by "taking into account pollen transport, as it has been done in our current study."

While the Munich study did not track how far pollen was transported, and only differentiated between local and long-range transport (meaning pollen coming from outside Bavaria), it provides a crucial key in our understanding of annual pollen patterns. Yuan says that future studies should account for "climate change scenarios [and] land use/land cover changes." He also adds that citizen scientists may be able to contribute to pollen studies, who can help collect local observations and contribute to data collection.

It doesn't look like the pollen season will shorten any time soon, but more research on the subject can provide a better understanding of global patterns and changes so that we can better address these issues in the future.

CAPTION

Trap for measuring abundances of windborne pollen

CREDIT

A. Menzel and Y. Yuan, Technical University of Munich