Heavens

Nature is an amazing source for food, shelter, clothing and medicine. An impressive number of modern drugs are isolated from many sources such as plants, animals and microbes. The development of natural products from traditional medicines is of great importance to society. Modern concepts and methodologies with abundant clinical studies, a unique diversity of chemical structures and biological activities aid the modern drug discovery process. Kedrostis foetidissima (Jacq.) Cogn., a traditional medicinal plant of the Cucurbitaceae family, is found in India, Sri Lanka, Ethiopia and Western Malaysia. Almost all parts of the plant are used in traditional systems of medicine and reported to have medicinal properties in both in vitro and in vivo studies. In the last few years, extensive research work has been carried out using extracts and isolated phytoconstituents from Kedrostis foetidissima to confirm its pharmacology and biological activities. Many scientific reports show that crude extracts and extensive numbers of phytochemical constituents isolated from Kedrostis foetidissima have activities like antimicrobial, antioxidant, anticancer, gastroprotective, anti-inflammatory and various other important medicinal properties. The therapeutic properties of the plants are mainly attributed to the existence of phytoconstituents like phenols, alkaloids, flavonoids, tannins, terpenoids and steroids. This comprehensive review presented by researchers from K.S. Rangasamy College of Arts and Science, Tiruchengode, Tamil-Nadu, India, gives readers a brief overview of phytoconstituents, nutritional values and medicinal properties of the plant. The reviewers hope that the information helps researchers to explore the plant's medicinal activity by discovering novel biologically active compounds that can serve as a lead compound in pharmaceutical and food industry.

A red beetle, classed as the most destructive date palm pest, causes millions of dollars of annual economic losses worldwide. Now, a small team in Saudi Arabia has found a cost-effective approach that uses laser pulses to detect the very early stages of infestation, giving farmers enough time to save their trees.

The red palm weevil is a flying beetle that feeds on and lays its eggs inside date palms. By the time weevil infestation causes visible signs of distress in the trees, it is too late to save them, explains KAUST research scientist, Islam Ashry. "Several methods are currently used to detect red palm weevil infestation, but they are not reliable or feasible in large palm farms," he says. These methods include using sniffer dogs, screening trees with computer-based tomography, and inserting sound probes into a tree's trunk to detect the munching sounds of weevil larvae.

While reading an article about the destructive impacts of these infestations, KAUST Professor Boon S. Ooi recognized that his work on photonics could be relevant. "Optical fibers can efficiently detect very weak sound over several kilometers," he explains. He led a team of researchers, in collaboration with Yousef Al-Fehaid at Saudi Arabia's Ministry of Environment, Water and Agriculture, to investigate whether fiber optics could be employed as a cost-effective and noninvasive means to detect the very early munching sounds made by young larvae.

They developed an approach that involves sending laser pulses from a sensing device into an optical fiber, which can be wrapped around the trunks of multiple trees over a vast area. Sound interacts with the light signal inside the fiber, changing its frequency. The fiber feeds the data back into the sensor that, with relative accuracy, can inform farmers which trees are healthy and which are infested.

Before using their system, the researchers recorded 12-day-old larvae to identify their sound signature. They also recorded and identified the sound signatures of typical background noises, like wind and birds. The frequencies of the sounds were different enough that they could apply a filter to their sensor that discards most irrelevant noises. They also developed an algorithm that analyzes the incoming signal to flesh out larval noises.

Lab-based tests on small trees demonstrated that the system reliably distinguished healthy trees from infested ones.

"Our sensor can provide noninvasive, 24/7, low-cost, simultaneous monitoring of around 1,000 palm trees with a 10-kilometer-long optic fiber, detecting larvae that are as young as 12 days old," says KAUST research scientist Yuan Mao.

The team next plans to deploy their sensing system in large-scale, open-air farms. "This will require modifications to the system to include advanced signal processing techniques that can discard the noises found in these environments," says Ashry.

For the first time, UBC researchers have shown a key difference in the three-dimensional structures of a key metabolic enzyme in the parasite that causes malaria compared to its human counterpart.

The finding, recently published in the International Union of Crystallography Journal, brings researchers one step closer to developing new therapies to combat drug-resistant malaria.

The structural differences of the metabolic enzyme, known as hexokinase, were captured using cryogenic electron microscopy or cryo-EM, whereby samples are cooled to cryogenic temperatures and examined at near-atomic resolution.

The researchers found that the enzyme in the malaria-causing parasite, known as Plasmodium, adopts a shape that has four individual subunits, while the enzyme in humans adopts a shape with just two subunits. This difference provides a unique opportunity to design drugs that specifically target the Plasmodium enzyme, without affecting the human version.

"Our new findings offer the prospect to design anti-malarial drugs that selectively target the unique structure of the parasite-infected cells, especially in the early stages of infection. Think of it as cutting a key based on the shape of the keyhole," says the study's senior author Dr. Sriram Subramaniam, the Gobind Khorana Canada Excellence Research Chair in UBC's faculty of medicine.

According to the World Health Organization, malaria, a mosquito-borne illness, affects more than 200 million individuals annually, resulting in the death of an estimated 400,000 each year. New treatments are in need, as resistance to the most common forms of anti-malarial drugs are on the rise, making the disease increasingly difficult to treat in some parts of the world.

"With this discovery, a new avenue for combatting drug-resistant malaria has opened," says the study's first author Dr. Shanti Swaroop Srivastava, a UBC postdoctoral fellow in Subramaniam's lab, which is recognized for world-leading contributions in cryo-EM. "Now that we know the atomic structural information of this key metabolic enzyme, new drugs can be developed to block the parasite's ability to metabolize glucose and survive."

The study, carried out in the laboratory of Dr. Subramaniam, was conducted in collaboration with research groups at Clemson University, led by Dr. James Morris, professor of genetics and biochemistry, and the Ohio State University Medical Center, led by Dr. Mark Drew, professor of microbial infection and immunity.

Researchers at the National Astronomical Observatory of Japan (NAOJ) have used the infrastructure of the former TAMA300 gravitational wave detector in Mitaka, Tokyo to demonstrate a new technique to reduce quantum noise in detectors. This new technique will help increase the sensitivity of the detectors comprising a collaborative worldwide gravitational wave network, allowing them to observe fainter waves.

When it began observations in 2000, TAMA300 was one of the world's first large-scale interferometric gravitational wave detectors. At that time TAMA300 had the highest sensitivity in the world, setting an upper limit on the strength of gravitational wave signals; but the first detection of actual gravitational waves was made 15 years later in 2015 by LIGO. Since then detector technology has improved to the point that modern detectors are observing several signals per month. The scientific results obtained from these observations are already impressive and many more are expected in the next decades. TAMA300 is no longer participating in observations, but is still active, acting as a testbed for new technologies to improve other detectors.

The sensitivity of current and future gravitational wave detectors is limited at almost all the frequencies by quantum noise caused by the effects of vacuum fluctuations of the electromagnetic fields. But even this inherent quantum noise can be sidestepped. It is possible to manipulate the vacuum fluctuations to redistribute the quantum uncertainties, deceasing one type of noise at the expense of increasing a different, less obstructive type of noise. This technique, known as vacuum squeezing, has already been implemented in gravitational wave detectors, greatly increasing their sensitivity to higher frequency gravitational waves. But the optomechanical interaction between the electromagnetic field and the mirrors of the detector cause the effects of vacuum squeezing to change depending on the frequency. So at low frequencies vacuum squeezing increases the wrong type of noise, actually degrading sensitivity.

To overcome this limitation and achieve reduced noise at all frequencies, a team at NAOJ composed of members of the in-house Gravitational Wave Science Project and the KAGRA collaboration (but also including researchers of the Virgo and GEO collaborations) has recently demonstrated the feasibility of a technique known as frequency dependent vacuum squeezing, at the frequencies useful for gravitational wave detectors. Because the detector itself interacts with the electromagnetic fields differently depending on the frequency, the team used the infrastructure of the former TAMA300 detector to create a field which itself varies depending on frequency. A normal (frequency independent) squeezed vacuum field is reflected off an optical cavity 300-m long, such that a frequency dependence is imprinted and it is able counteract the optomechanical effect of the interferometer.

This technique will allow improved sensitivity at both high and low frequencies simultaneously. This is a crucial result demonstrating a key-technology to improve the sensitivity of future detectors. Its implementation, planned as a near term upgrade together with other improvements, is expected to double the observation range of second-generation detectors.

Osaka - Understanding the behavior of proteins and enzymes is key to unlocking the secrets of biological processes. The atomic structures of proteins are generally investigated using X-ray crystallography; however, the precise information for hydrogen atoms and protons (hydrogen ions) is usually unattainable. Now a team including Osaka University, Osaka Medical College, National Institutes for Quantum and Radiological Science and Technology, Ibaraki University, and University of Tsukuba has used neutron crystallography to reveal high-resolution structural details of a very large oxidase protein. Their findings are published in PNAS.

The hydrogen atoms and protons that make up about half of the atoms in proteins and enzymes often play crucial roles in the jobs these biomolecules do; however, their exact positions are difficult to pinpoint because of their small size. The most common approach for working out the structure of a protein is to direct a beam of high-energy X-rays at a protein crystal and analyze the diffraction pattern that results from the interactions of the X-rays with the electrons of atoms in the structure. Unfortunately, X-rays do not interact strongly with hydrogen atoms or protons, which have low or no electron density, making them difficult to "see."

One solution is to apply a neutron beam to the crystal instead of X-rays. Neutrons interact with the nuclei of the atoms in their path, including those of hydrogen atoms and protons, despite them being small. The diffraction patterns resulting from these interactions are recorded after the neutron beam has passed through the crystal, and are decoded into the precise locations of the nuclei, including the hydrogen nuclei.

"Hydrogen atoms and protons are particularly interesting components of enzyme structures because they can exhibit quantum behaviors that have recently been found to be crucial to enzyme function. It is therefore important to accurately determine their locations in the protein structure in order to unravel what is happening," study corresponding author Toshihide Okajima explains. "Using neutron crystallography, we were able to determine the structure of a bacterial copper amine oxidase with a molecular weight of 70,600—which is extremely large for neutron crystallography and significantly exceeds previously recorded molecular masses—and still precisely locate the hydrogen atoms and protons in the structure. An unusual "levitated" proton was observed between a cofactor, topa quinone, and an amino acid residue strictly conserved in this class of enzymes."

The topa quinone cofactor covalently bound to the enzyme plays an essential role in the catalytic function. The researchers were finally able to establish a complete picture of topa quinone 30 years after its discovery as a protein-derived cofactor. They found that the cofactor actually exists in equilibrium between two different forms.

"Enzyme active sites—where the reactions take place—can provide us a great deal of information and inspiration if we are able to fully understand what is happening," Okajima explains. "Our demonstration of using neutron crystallography to uncover proton quantum effects promises to be very useful for many researchers studying enzymes and their mechanisms."

To achieve your goals you need passion, grit and a positive mindset - or expressed another way, the belief that you'll succeed if you just keep at it.

But what's the connection between these factors, and what's the most important one? That, it turns out, depends on who you are.

A recent study has investigated the links between this particular combination of factors. Previous studies show that many factors play a role in achieving success. But the new research reveals that what is most important can vary between the sexes.

"We found big differences between the sexes in some areas," says Professor Hermundur Sigmundsson at the Norwegian University of Science and Technology's (NTNU) Department of Psychology.

Women and men have about the same degree of grit and positive mindset. Men, however, have significantly higher scores on the passion factor.

For women, all the factors - passion, grit and a positive mindset - are closely intertwined. All three factors are quite strongly correlated with each other.

The researchers did not find this strong interconnectedness to the same degree in men.

Nor did they find a strong correlation between attitude and positive mindset. What they did find in men was a strong interaction between passion and grit.

"Men have to burn more for something to succeed at it. They need to be more passionate about what they undertake," says Sigmundsson.

The fact that passion is so important for men who want to achieve good results is an important finding that could prove useful for people involved in shaping the education of the future.

Sigmundsson and his research colleagues speculate whether this finding might be a reason why girls generally do better at school.

Boys apparently need to be more fervently enthusiastic about a topic for their grit to kick in. Perhaps this finding should impact how we educate, and can lead us to concentrate more on students' individual interests, strengths and resources. We may need to if we want to light the fire of more boys.

This doesn't mean that a positive mindset does not play any role for men. Mindset is an important underlying factor for everyone, and multiple factors come into play regardless of gender.

"But even though a positive mindset is a good starting point, it isn't enough. You also need focused training, passion, grit, and support from others - like mentors, teachers and coaches," says Sigmundsson.

The survey was conducted in Iceland, with 146 young Icelanders participating.

By tracking the thick clouds of Venus' rapidly rotating atmosphere, researchers have gained new insight into the dynamic forces that drive atmospheric super-rotation - a little-understood phenomenon in which an atmosphere rotates much faster than the solid planetary body below. Based on observations from the Japan Aerospace Exploration Agency (JAXA) spacecraft Akatsuki, which has been orbiting Venus since 2015, the study suggests that super-rotation is maintained by a combination of solar heating-driven thermal tides, planetary waves and atmospheric turbulence. "Among the intriguing mysteries that remain for planetary atmospheres, the phenomenon of super-rotation is still a teasing problem," writes Sebastion Lebonnois in a related Perspective. Compared to Earth, the rotation of Venus is slow - its surface takes 243 Earth days to complete one rotation. However, the Venusian atmosphere spins nearly 60 times faster, whipping around the planet once every 96 hours. For this phenomenon to occur, a continuous redistribution of angular momentum is needed to overcome friction with the planet's surface, although neither the source of this momentum nor how it's maintained are known. Using ultraviolet images and thermal infrared measurements taken by Akatsuki, Takeshi Horinouchi and colleagues tracked the motion of clouds and used them to map the planet's winds, which provided the authors with a consistent picture of Venus' angular momentum balance at the cloud-top level. These data allowed Horinouchi et al. to estimate the atmospheric forces sustaining the planet's super-rotating atmosphere. Their results show the required angular momentum is provided through thermal tides, driven by solar heating near the planet's equator, and is opposed by planetary-scale waves (called Rossby waves) and large-scale atmospheric turbulence. "Horinouchi et al. provide an important piece of the super-rotation puzzle, that can offer a strong constraint on numerical simulations of the Venusian atmosphere," Lebonnois writes.

New research indicates river delta deposits within Mars’ Jezero crater – the destination of NASA’ Perseverance rover on the Red Planet – formed over time scales that promoted habitability and enhanced preservation of evidence.

Undulating streaks of land visible from space reveal rivers once coursed across the Martian surface – but for how long did the water flow? Enough time to record evidence of ancient life, according to a new Stanford study.

Scientists have speculated that the Jezero crater on Mars – the site of the next NASA rover mission to the Red Planet – could be a good place to look for markers of life. A new analysis of satellite imagery supports that hypothesis. By modeling the length of time it took to form the layers of sediment in a delta deposited by an ancient river as it poured into the crater, researchers have concluded that if life once existed near the Martian surface, traces of it could have been captured within the delta layers.

“There probably was water for a significant duration on Mars and that environment was most certainly habitable, even if it may have been arid,” according to lead author Mathieu Lapôtre, an assistant professor of geological sciences at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “We showed that sediments were deposited rapidly and that if there were organics, they would have been buried rapidly, which means that they would likely have been preserved and protected.”

Jezero crater was selected for NASA’s next rover mission partly because the site contains a river delta, which on Earth are known to effectively preserve organic molecules associated with life. But without an understanding of the rates and durations of delta-building events, the analogy remained speculative. The new research, published online on April 23 in AGU Advances, offers guidance for sample recovery in order to better understand the ancient Martian climate and duration of the delta formation for NASA’s Perseverance Rover to Mars, which is expected to launch in July 2020 as part of the first Mars sample return mission.

Extrapolating from Earth

The study incorporates a recent discovery the researchers made about Earth: Single-threaded sinuous rivers that don’t have plants growing over their banks move sideways about ten times faster than those with vegetation. Based on the strength of Mars’ gravity, and assuming the Red Planet did not have plants, the scientists estimate that the delta in Jezero crater took at least 20 to 40 years to form, but that formation was likely discontinuous and spread out across about 400,000 years.

“This is useful because one of the big unknowns on Mars is time,” Lapôtre said. “By finding a way to calculate rate for the process, we can start gaining that dimension of time.”

Because single-threaded, meandering rivers are most often found with vegetation on Earth, their occurrence without plants remained largely undetected until recently. It was thought that before the appearance of plants, only braided rivers, made up of multiple interlaced channels, existed. Now that researchers know to look for them, they have found meandering rivers on Earth today where there are no plants, such as in the McLeod Springs Wash in the Toiyabe basin of Nevada.

“This specifically hadn’t been done before because single-threaded rivers without plants were not really on anyone’s radar,” Lapôtre said. “It also has cool implications for how rivers might have worked on Earth before there were plants.”

The researchers also estimated that wet spells conducive to significant delta buildup were about 20 times less frequent on ancient Mars than they are on Earth today.

“People have been thinking more and more about the fact that flows on Mars probably were not continuous and that there have been times when you had flows and other times when you had dry spells,” Lapôtre said. “This is a novel way of putting quantitative constraints on how frequently flows probably happened on Mars.”

Findings from Jezero crater could aid our understanding of how life evolved on Earth. If life once existed there, it likely didn’t evolve beyond the single-cell stage, scientists say. That’s because Jezero crater formed over 3.5 billion years ago, long before organisms on Earth became multicellular. If life once existed at the surface, its evolution was stalled by some unknown event that sterilized the planet. That means the Martian crater could serve as a kind of time capsule preserving signs of life as it might once have existed on Earth.

“Being able to use another planet as a lab experiment for how life could have started somewhere else or where there’s a better record of how life started in the first place – that could actually teach us a lot about what life is,” Lapôtre said. “These will be the first samples that we’ve seen as a rock on Mars and then brought back to Earth, so it’s pretty exciting.”

A small survey conducted by researchers at the Johns Hopkins Bloomberg School of Public Health found that more than half of respondents who reported having attempted to acquire a firearm in Baltimore's underground firearm market in the prior six months were unsuccessful-- some due to lack of financial means, and others reporting they had no trusted point of contact for acquiring guns through unlawful means.

The findings, published online in the journal Violence and Gender, provide a description of motivations for involvement among those with experience trying to obtain a gun in Baltimore's underground gun market.

Underground gun markets, or gun sales that occur outside of lawful transfers, can create opportunities for prohibited or high-risk individuals to obtain access to guns. Gun violence often involves individuals who are prohibited from legally posessing firearms because of criminal history, restraining orders, or age. Previous research has found that more than 40 percent of people incarcerated for crimes with guns obtained those guns from the street or underground market.

"Understanding the underground market--how firearms are purchased, stolen, traded, or sold--can help provide a roadmap to prevent a prohibited person's access to guns," says lead author Cassandra Crifasi, PhD, MPH, deputy director of the Johns Hopkins Center for Gun Policy and Research and assistant professor in the Bloomberg School's Department of Health Policy and Management.

For the study, the researchers surveyed 195 men on probation and/or parole in Baltimore, Maryland in 2016 to understand how individuals obtain and transfer firearms in underground gun markets. Of these, 58, or 30 percent, reported attempting to acquire a gun in the underground market in the prior six months.

Within this subgroup of 58 respondents, the majority reported having access to a handgun as compared to other types of firearms. Thirty-one percent of the subgroup (18) said there were employees at certain gun shops who would allow off-record purchases and/or straw purchases, when someone acquires a gun and gives it to someone else. In addition, almost a quarter of respondents--24 percent--who tried to get a gun in the last six months reported that there are certain gun shops in Maryland where it is easier to get a gun without background checks, and 16 percent said there were gun shops where it was easier to steal guns.

Sixty percent (35 of 58) reported selling or trading a gun, with the majority (69 percent) selling or trading for money, 46 percent for drugs, and 23 percent for other guns. The two most frequently reported reasons for being unsuccessful acquiring a gun in the underground market were not having a trusted source (42 percent) or resources to pay for one (23 percent).

Baltimore's murder rate in 2015--the year immediately preceding the study survey--was at that time the highest in the city's history. According to Baltimore Police Department data, 87 percent of the city's homicides were committed with firearms in 2015. Previous research has shown that policies that reduce high-risk individuals' access to firearms can reduce violence, and policies that improve firearm seller accountability can be effective at reducing diversion of guns for criminal use. In 2013, the Maryland passed the Firearm Safety Act, legislation with several components that could potentially reduce diversion of guns into the hands of prohibited persons, including permit-to-purchase laws for handguns, which include background checks and fingerprinting, expanding authority for state police to act against gun dealers who violate state gun sales laws, and banning the sale of assault rifles.

"We frequently hear that gun laws infringe upon a law-abiding citizen," says Crifasi. "However, our findings challenge that narrative and suggest that laws that focus on supply-side constraints--like permit-to-purchase laws--might actually be effective in preventing individuals who are prohibited from getting a gun, especially in times of increased violence."

The researchers recruited participants in public spaces directly outside seven parole and probation centers across Baltimore, Maryland, from May to August 2016. Participants were included if they were male, age 18 or older, currently on probation or parole, and living in Baltimore city. Participants, who were compensated with a gift card, answered questions about 1) access to and desire for guns; 2) gun-purchasing activities; 3) gun-selling activities; and 4) the number and types of guns to which they had access. Researchers identified 216 participants and used 195 survey responses for their analysis.

Eighty percent of the total sample of 195 individuals identified as African American, 74 percent were unemployed, and 63 percent reported being shot at least one time. Fifty-two participants, or 27 percent of the total sample, had access to a gun through direct ownership or borrowing. Of the 137 survey participants who reported not having access to a gun in the prior six months, more than a quarter, 27 percent (38), wanted to get one, with 31, or 81 percent, reporting safety or protection as the main reasons for wanting a gun.

"Understanding the context for why an individual wants a gun is key," says Crifasi. "Since safety was a main motivator for individuals wanting a gun, efforts that focus on preventing and responding to violence, improving police and community relationships, and increasing feelings of safety may lead to fewer people to feel the need to acquire guns through an underground market."

"Baltimore's Underground Gun Market: Availability of and Access to Guns" was written by Cassandra K. Crifasi, Shani A. L. Buggs, Marisa D. Booty, Daniel W. Webster and Susan G. Sherman.

EUGENE, Ore. - April 15, 2020 -- When species under a taxonomic umbrella have faced forks in the road, leading to extinction or adaptation, the path taken has been difficult to follow. In a newly published paper, two scientists argue that long-used approaches for reconstructing these paths are deeply flawed.

While paleontological evidence provides insights on how and why patterns of biodiversity have changed over geological time, fossil finds for many types of organisms are too scant to say anything, said University of Oregon biologist Stilianos Louca, lead author of a paper placed online April 15 ahead of print in the journal Nature.

An alternative approach, he noted, relies on using identifiable changes in an organism's genetic makeup, but the signal in this type of data can be misleading.

"Our finding casts serious doubts over literally thousands of studies that use phylogenetic trees of extant data to reconstruct the diversification history of taxa, especially for those taxa where fossils are rare, or that found correlations between environmental factors such as changing global temperatures and species extinction rates," said Louca, who is a member of the UO's Institute of Ecology and Evolution.

In their paper, Louca and Matthew W. Pennell, an evolutionary biologist at the University of British Columbia in Vancouver, also offer a way forward - a mathematical model that introduces alternative variables to characterize long-term evolutionary scenarios that can be accurately identified from phylogenetic data.

"I have been working with these traditional types of models for a decade now," Pennell said. "I am one of the lead developers of a popular software package for estimating diversification rates from phylogenetic trees. And, as such, I thought I had a really good sense of how these models worked. I was wrong."

In their paper, the researchers note that long-used methods extract information about evolution from still-living organisms, using variants of a mathematical birth-death process. These, however, cannot possibly extract information about both speciation and extinction rates, especially for a majority of taxa, such as bacteria, that have left no fossil record.

The paleontological approach estimates the number of species that have appeared and disappeared in various intervals based on discovered fossils and their estimated minimum and maximum ages. In the phylogenetic approach, information is extracted from evolutionary relationships between existing species, using mostly genetic data, and structured in phylogenetic trees known as timetrees.

This is often done by finding a speciation/extinction scenario that would have been the most likely to generate a given phylogenetic tree.

"While an impressive suite of computational methods has been developed over the past decades for extracting whatever information is left, until now we lacked a good understanding of exactly what information is left in these trees, and what information is forever lost," Louca said.

Louca and Pennell's mathematically driven approach clarifies precisely what information can be extracted from extant timetrees under the generalized birth-death model. The researchers introduce new identifiable and easily interpretable variables that contain all available information about past diversification dynamics and how they can be estimated.

"We suggest that measuring and modeling these identifiable variables offers a more robust way to study historical diversification dynamics," they write in the paper. "Our findings also make clear that paleontological data will continue to be crucial for answering some macroevolutionary questions."

"The future depends on synthesizing information from datasets of both molecules and fossils," Pennell said.

The researchers emphasize that their results do not invalidate the theory of evolution itself, they just put constraints on what type of information can possibly be extracted from genetic data to reconstruct evolution's path.

Since its discovery in 2017, an air of mystery has surrounded the first known interstellar object to visit our solar system, an elongated, cigar-shaped body named 'Oumuamua (Hawaiian for "a messenger from afar arriving first").

How was it formed, and where did it come from? A new study published April 13 in Nature Astronomy offers a first comprehensive answer to these questions.

First author Yun Zhang at the National Astronomical Observatories of the Chinese Academy of Sciences and coauthor Douglas N. C. Lin at the University of California, Santa Cruz, used computer simulations to show how objects like 'Oumuamua can form under the influence of tidal forces like those felt by Earth's oceans. Their formation theory explains all of 'Oumuamua's unusual characteristics.

"We showed that 'Oumuamua-like interstellar objects can be produced through extensive tidal fragmentation during close encounters of their parent bodies with their host stars, and then ejected into interstellar space," said Lin, professor emeritus of astronomy and astrophysics at UC Santa Cruz.

Discovered on October 19, 2017, by the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1) in Hawaii, 'Oumuamua is absolutely nothing like anything else in our solar system, according to Zhang. Its dry surface, unusually elongated shape, and puzzling motion even drove some scientists to wonder if it was an alien probe.

"It is really a mysterious object, but some signs, like its colors and the absence of radio emission, point to 'Oumuamua being a natural object," Zhang said.

"Our objective is to come up with a comprehensive scenario, based on well understood physical principles, to piece together all the tantalizing clues," Lin said.

Astronomers had expected that the first interstellar object they detected would be an icy body like a comet. Icy objects like those populating the Oort cloud, a reservoir of comets in the outermost reaches of our solar system, evolve at very large distances from their host stars, are rich in volatiles, and are often tossed out of their host systems by gravitational interactions. They are also highly visible due to the sublimation of volatile compounds, which creates a comet's coma (or "tail") when it is warmed by the sun. 'Oumuamua's dry appearance, however, is similar to rocky bodies like the solar system's asteroids, indicating a different ejection scenario.

Other researchers have calculated that there must be an extremely large population of interstellar objects like 'Oumuamua. "The discovery of 'Oumuamua implies that the population of rocky interstellar objects is much larger than we previously thought," Zhang said. "On average, each planetary system should eject in total about a hundred trillion objects like 'Oumuamua. We need to construct a very common scenario to produce this kind of object."

When a smaller body passes very close to a much bigger one, tidal forces of the larger body can tear the smaller one apart, as happened to comet Shoemaker-Levy 9 when it came close to Jupiter. The tidal disruption processes can eject some debris into interstellar space, which has been suggested as a possible origin for 'Oumuamua. But whether such a process could explain 'Oumuamua's puzzling characteristics remained highly uncertain.

Zhang and Lin ran high-resolution computer simulations to model the structural dynamics of an object flying close by a star. They found that if the object comes close enough to the star, the star can tear it into extremely elongated fragments that are then ejected into the interstellar space.

"The elongated shape is more compelling when we considered the variation of material strength during the stellar encounter. The ratio of long axis to short axis can be even larger than ten to one," Zhang said.

The researchers' thermal modeling showed that the surface of fragments resulting from the disruption of the initial body would melt at a very short distance from the star and recondense at greater distances, thereby forming a cohesive crust that would ensure the structural stability of the elongated shape.

"Heat diffusion during the stellar tidal disruption process also consumes large amounts of volatiles, which not only explains 'Oumuamua's surface colors and the absence of visible coma, but also elucidates the inferred dryness of the interstellar population," Zhang said. "Nevertheless, some high-sublimation-temperature volatiles buried under the surface, like water ice, can remain in a condensed form."

Observations of 'Oumuamua showed no cometary activity, and only water ice is a possible outgassing source to account for its non-gravitational motion. If 'Oumuamua was produced and ejected by the scenario of Zhang and Lin, plenty of residual water ice could be activated during its passage through the solar system. The resulting outgassing would cause accelerations that match 'Oumuamua's comet-like trajectory.

"The tidal fragmentation scenario not only provides a way to form one single 'Oumuamua, but also accounts for the vast population of asteroid-like interstellar objects," Zhang said.

The researchers' calculations demonstrate the efficiency of tidal forces in producing this kind of object. Possible progenitors, including long-period comets, debris disks, and even super-Earths, could be transformed into 'Oumuamua-size pieces during stellar encounters.

This work supports estimates of a large population of 'Oumuamua-like interstellar objects. Since these objects may pass through the domains of habitable zones, the possibility that they could transport matter capable of generating life (called panspermia) cannot be ruled out. "This is a very new field. These interstellar objects could provide critical clues about how planetary systems form and evolve," Zhang said.

According to Lin, "'Oumuamua is just the tip of the iceberg. We anticipate many more interstellar visitors with similar traits will be discovered by future observation with the forthcoming Vera C. Rubin Observatory."

U.S. Naval Academy astronomer Matthew Knight, who is co-leader of the 'Oumuamua International Space Science Institute team and was not involved in the new study, said this work "does a remarkable job of explaining a variety of unusual properties of 'Oumuamua with a single, coherent model."

"As future interstellar objects are discovered in coming years, it will be very interesting to see if any exhibit 'Oumuamua-like properties. If so, it may indicate that the processes described in this study are widespread," Knight said.

Nowadays, modern quantum simulators offer a wide range of possibilities to prepare and investigate complex quantum states. They are realized with ultracold atoms in optical lattices, Rydberg atoms, trapped ions or superconducting quantum bits. A particularly fascinating class of quantum states are topological states of matter. David Thouless, Duncan Haldane and Michael Kosterlitz were awarded the Nobel Prize in Physics in 2016 for their theoretical discovery. These states of matter are characterized by nonlocal quantum correlations and are particularly robust against local distortions that inevitably occur in experiments. "Identifying and characterizing such topological phases in experiments is a great challenge," say Benoît Vermersch, Jinlong Yu and Andreas Elben from the Center for Quantum Physics at the University of Innsbruck and the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences. "Topological phases cannot be identified by local measurements because of their special properties. We are therefore developing new measurement protocols that will enable experimental physicists to characterize these states in the laboratory". In recent years this has already been achieved for non-interacting systems. However, for interacting systems, which in the future could also be used as topological quantum computers, this has not been possible so far.

With random measurements to a definite result

In Science Advances, the physicists of Peter Zoller's research group now propose measurement protocols that enable the measurement of so-called topological invariants. These mathematical expressions describe common properties of topological spaces and make it possible to fully identify interacting topological states with global symmetry in one-dimensional, bosonic systems. "The idea of our method is to first prepare such a topological state in a quantum simulator. Now so-called random measurements are performed, and topological invariants are extracted from statistical correlations of these random measurements," explains Andreas Elben. The specific feature of this method is that although the topological invariants are highly complex, non-local correlation functions, they can still be extracted from statistical correlations of simple, local random measurements. As with a method recently presented by the research group for comparing quantum states in computers or simulators, such random measurements are possible in experiments today. "Our protocols for measuring the topological invariants can therefore be directly applied in the existing experimental platforms," says Benoît Vermersch.

An international research team led by the Department of Physics and Astronomy at the University of Turku, Finland, mapped the interstellar magnetic field structure and interstellar matter distribution in the solar neighbourhood. The results of the study have been published in the esteemed European journal Astronomy & Astrophysics (A&A) in March.

Magnetic field has an important role in the processes of stellar and planetary system formation. The study led by Docent Vilppu Piirola and Docent Andrei Berdyugin is based on high-precision polarisation measurements. Starlight passing through interstellar clouds is polarised by scattering from dust particles aligned by the magnetic field.

-- Polarisation means that electromagnetic oscillation is stronger in a specific direction that is perpendicular to the direction of motion of the light. The alignment of small, less than one micrometer in size, elongated dust particles is based on the same phenomenon as a compass needle aligning with the Earth's magnetic field, although it is a more complicated process, explains Vilppu Piirola.

What makes the study particularly significant, is its connection with the results obtained from the Interstellar Boundary EXplorer (IBEX) orbiter sent to explore the interaction between the Sun and the magnetic field in the solar neighbourhood. The Sun and its magnetic field interact with the surrounding interstellar matter, and the solar wind creates a so-called local bubble where the matter density is low and only little dust exists. The task of the IBEX is to observe the interface between the Sun's heliosphere and interstellar space and matter where the solar wind practically stops.

High-precision Equipment Reveal Magnetic Field Direction

The IBEX receives information of the interstellar magnetic field (ISMF) by observing energetic neutral atoms (e.g. neutral hydrogen) that pass through the heliospheric boundary. The ISMF direction, however, can be accurately determined only by polarisation measurements. High-precision equipment with polarisation detection sensitivity at the level of or better than 0.001 % (one part in hundred thousand) has been developed for these type of measurements at the Tuorla Observatory of the University of Turku.

Four telescopes have been used for the observations of this recently published study: two in Hawaii (Mauna Kea and Haleakala observatories), one in La Palma (Nordic Optical Telescope), and one in the southern hemisphere at the Greenhill Observatory of the University of Tasmania.

-- The observations have revealed interesting magnetic filament structures both in the direction where our solar system is moving in relation to the surrounding interstellar space (heliosphere 'nose') and in the opposite direction (heliosphere 'tail'). The filaments form ribbon-like arcs where dust particles and starlight polarisation have aligned with the direction of the magnetic field, says Piirola.

Magnetic monopoles were detected for the first time worldwide at the Berlin Neutron Source BER II in 2008. At that time they in a one-dimensional spin system of a dysprosium compound. About 10 years ago, monopole quasi-particles could also be detected in two-dimensional spin-ice systems consisting of tetrahedral crystal units. However, these spin-ice materials were electrical insulators.

Now: Magnetic monopoles in a metal

Dr. Kan Zhao and Prof. Philipp Gegenwart from the University of Augsburg, together with teams from the Heinz Meier Leibnitz Centre, Forschungszentrum Jülich, the University of Colorado, the Academy of Sciences in Prague and the Helmholtz-Zentrum Berlin, have now shown for the first time that a metallic compound can also form such magnetic monopoles. The team in Augsburg prepared crystalline samples from the elements holmium, silver and germanium for this purpose.

Kagome spin-ice system means frustration

In the HoAgGe crystals, the magnetic moments (spins) of the holmium atoms form a so-called two-dimensional Kagome pattern. This name comes from the Japanese Kagome braiding art, in which the braiding bands are not woven at right angles to each other, but in such a way that triangular patterns are formed.

In the Kagome-pattern the spins of neighbouring atoms can not be aligned contrary to each other as usual. Instead, there are two permitted spin configurations: Either the spins of two of the three atoms point exactly towards the center of the triangle, while those of the third atom point out of the center. Or it is exactly the other way round: One spin points to the center, the other two out of it. This limits the possibilities of spin arrangements - hence the name "Kagome spin ice." One consequence of this is that this system behaves as if magnetic monopoles were present in it.

This behaviour has now been experimentally demonstrated for the first time in HoAgGe crystals by the cooperation lead by the Augsburg researchers. They cooled the samples near absolute zero temperature and examined them under external magnetic fields of varying strength. Part of the experiments were carried out at the Heinz Maier-Leibnitz Centre in Garching near Munich. They were supported by the department of sample environment of the HZB, which provided a superconducting cryomagnet for the experiments at the FRM-II.

Data on the spin energy spectrum at NEAT

Thus they were able to generate different spin arrangements, which are expected in a Kagome spin ice system. Model calculations from the Augsburg research team showed what the energy spectrum of the spins should look like. This energy spectrum of the spins could then be measured using the method of inelastic neutron scattering at the NEAT instrument at the Berlin neutron source. "This was the final building block for detecting the magnetic monopoles in this system. The agreement with the theoretically predicted spectra is really excellent" says Dr. Margarita Russina, who is responsible for the NEAT instrument at HZB.

The upper layers in the atmospheres of gas giants -- Saturn, Jupiter, Uranus and Neptune -- are hot, just like Earth's. But unlike Earth, the Sun is too far from these outer planets to account for the high temperatures. Their heat source has been one of the great mysteries of planetary science.

New analysis of data from NASA's Cassini spacecraft finds a viable explanation for what's keeping the upper layers of Saturn, and possibly the other gas giants, so hot: auroras at the planet's north and south poles. Electric currents, triggered by interactions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the upper atmosphere. (As with Earth's northern lights, studying auroras tells scientists what's going on in the planet's atmosphere.)

The work, published today in Nature Astronomy, is the most complete mapping yet of both temperature and density of a gas giant's upper atmosphere - a region that has been poorly understood.

"Understanding the dynamics really requires a global view. This dataset is the first time we've been able to look at the upper atmosphere from pole to pole while also seeing how temperature changes with depth," said Zarah Brown, lead author of the study and a graduate student in the University of Arizona Lunar and Planetary Laboratory.

By building a complete picture of how heat circulates in the atmosphere, scientists are better able to understand how auroral electric currents heat the upper layers of Saturn's atmosphere and drive winds. The global wind system can distribute this energy, which is initially deposited near the poles toward the equatorial regions, heating them to twice the temperatures expected from the sun's heating alone.

"The results are vital to our general understanding of planetary upper atmospheres and are an important part of Cassini's legacy," said study co-author Tommi Koskinen, a member of Cassini's Ultraviolet Imaging Spectograph team. "They help address the question of why the uppermost part of the atmosphere is so hot, while the rest of the atmosphere - due to the large distance from the Sun - is cold."

Managed by NASA's Jet Propulsion Laboratory in Southern California, Cassini was an orbiter that observed Saturn for more than 13 years before exhausting its fuel supply. The mission plunged it into the planet's atmosphere in September 2017, in part to protect its moon Enceladus, which Cassini discovered might hold conditions suitable for life. But before its plunge, Cassini performed 22 ultra-close orbits of Saturn, a final tour called the Grand Finale.

It was during the Grand Finale that the key data was collected for the new temperature map of Saturn's atmosphere. For six weeks, Cassini targeted several bright stars in the constellations of Orion and Canis Major as they passed behind Saturn. As the spacecraft observed the stars rise and set behind the giant planet, scientists analyzed how the starlight changed as it passed through the atmosphere.

Measuring how dense the atmosphere is gave scientists the information they needed to find the temperatures. Density decreases with altitude, and the rate of decrease depends on temperature. They found that temperatures peak near the auroras, indicating that auroral electric currents heat the upper atmosphere.

Density and temperature measurements together helped scientists figure out wind speeds. Understanding Saturn's upper atmosphere, where planet meets space, is key to understanding space weather and its impact on other planets in our solar system and exoplanets around other stars.

"Even though thousands of exoplanets have been found, only the planets in our solar system can be studied in this kind of detail. Thanks to Cassini, we have a more detailed picture of Saturn's upper atmosphere right now than any other giant planet in the universe," Brown said.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, or JPL, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter.