Largest virtual universe free for anyone to explore

Forget about online games that promise you a "whole world" to explore. An international team of researchers has generated an entire virtual UNIVERSE, and made it freely available on the cloud to everyone.

Uchuu (meaning "Outer Space" in Japanese) is the largest and most realistic simulation of the Universe to date. The Uchuu simulation consists of 2.1 trillion particles in a computational cube an unprecedented 9.63 billion light-years to a side. For comparison, that's about three-quarters the distance between Earth and the most distant observed galaxies. Uchuu will allow us to study the evolution of the Universe on a level of both size and detail inconceivable until now.

Uchuu focuses on the large-scale structure of the Universe: mysterious halos of dark matter which control not only the formation of galaxies, but also the fate of the entire Universe itself. The scale of these structures ranges from the largest galaxy clusters down to the smallest galaxies. Individual stars and planets aren't resolved, so don't expect to find any alien civilizations in Uchuu. But one way that Uchuu wins big in comparison to other virtual worlds is the time domain; Uchuu simulates the evolution of matter over almost the entire 13.8 billion year history of the Universe from the Big Bang to the present. That is over 30 times longer than the time since animal life first crawled out of the seas on Earth.

Julia F. Ereza, a Ph.D. student at IAA-CSIC who uses Uchuu to study the large-scale structure of the Universe explains the importance of the time domain, "Uchuu is like a time machine: we can go forward, backward and stop in time, we can 'zoom in' on a single galaxy or 'zoom out' to visualize a whole cluster, we can see what is really happening at every instant and in every place of the Universe from its earliest days to the present, being an essential tool to study the Cosmos."

An international team of researchers from Japan, Spain, U.S.A., Argentina, Australia, Chile, France, and Italy created Uchuu using ATERUI II, the world's most powerful supercomputer dedicated to astronomy. Even with all this power, it still took a year to produce Uchuu. Tomoaki Ishiyama, an associate professor at Chiba University who developed the code used to generate Uchuu, explains, "To produce Uchuu we have used ... all 40,200 processors (CPU cores) available exclusively for 48 hours each month. Twenty million supercomputer hours were consumed, and 3 Petabytes of data were generated, the equivalent of 894,784,853 pictures from a 12-megapixel cell phone."

Before you start worrying about download time, the research team used high-performance computational techniques to compress information on the formation and evolution of dark matter haloes in the Uchuu simulation into a 100-terabyte catalog. This catalog is now available to everyone on the cloud in an easy to use format thanks to the computational infrastructure skun6 located at the Instituto de Astrofísica de Andalucía (IAA-CSIC), the RedIRIS group, and the Galician Supercomputing Center (CESGA). Future data releases will include catalogues of virtual galaxies and gravitational lensing maps.

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Personality matters, even for squirrels

Humans acknowledge that personality goes a long way, at least for our species. But scientists have been more hesitant to ascribe personality -- defined as consistent behavior over time -- to other animals.

A study from the University of California, Davis is the first to document personality in golden-mantled ground squirrels, which are common across the western U.S. and parts of Canada. The study, published in the journal Animal Behaviour, found the squirrels show personality for four main traits: boldness, aggressiveness, activity level and sociability.

While the golden-mantled ground squirrel is under no conservation threat, the findings suggest that understanding how an animal's personality influences use of space is important for wildlife conservation.

'Individuals matter'

To see them chitter and skitter, stop and then scurry, the fact that ground squirrels have personalities may not seem surprising. But the scientific field of animal personality is relatively young, as is the recognition that there are ecological consequences of animal personality. For instance, bolder, more aggressive squirrels may find more food or defend a larger territory, but their risky behavior may also make them vulnerable to predation or accidents.

"This adds to the small but growing number of studies showing that individuals matter," said lead author Jaclyn Aliperti, who conducted the study while earning her Ph.D. in ecology at UC Davis. "Accounting for personality in wildlife management may be especially important when predicting wildlife responses to new conditions, such as changes or destruction of habitat due to human activity."

Personality tests

Scientists have been studying golden-mantled ground squirrels at the Rocky Mountain Biological Laboratory in Gothic, Colorado for decades. It was established as a long-term study site more than 30 years ago by Aliperti's advisor, Dirk Van Vuren, a professor in the UC Davis Department of Wildlife, Fish and Conservation Biology.

Aliperti drew from this powerful data set for her study, while also initiating a series of experiments there over the course of three summers to observe and quantify the squirrels' personalities.

She notes that while there are no Meyers-Briggs tests for animals, there are standardized approaches to quantifying animal personalities. She observed and recorded squirrel responses to four tests:
 

• Novel environment: Squirrels were placed in an enclosed box with gridded lines and holes.
• Mirror: Squirrels are presented with their mirror image, which they do not recognize as their own.
• Flight initiative: Squirrels were approached slowly in the wild to see how long they wait before running away.
• Behavior-in-trap: Squirrels were caught, unharmed, in a simple trap and their behavior briefly observed.

The social squirrel's advantage

Overall, the study found that bolder squirrels had larger core areas where they concentrated their activity. Bold, active squirrels moved faster. Also, squirrels that were bolder, more aggressive and more active had greater access to perches, such as rocks. Perch access is important because it can provide a better vantage point for seeing and evading predators. Interestingly, perch access was also associated with sociability.

Golden-mantled ground squirrels are considered an asocial species. They are relatively small, giving them little opportunity to form the tighter social bonds common in larger ground squirrels, which typically spend more time in family units while reaching maturity. However, the study said that "within this asocial species, individuals that tend to be relatively more social seem to have an advantage."

In such cases, being more social could save an individual's life. Such personality differences can influence a squirrel's ability to survive and reproduce, which could scale up to the population or community level.

Squirrels of Davis

UC Davis is home to many squirrels, which have become an honorary mascot of sorts on campus.

"The squirrels of UC Davis are something else," said Aliperti.

She means it literally. They are tree squirrels and very different from the ground squirrels Aliperti studied. Yet she says her work has changed how she views the squirrels of Davis.

"I view them more as individuals," Aliperti said. "I view them as, 'Who are you? Where are you going? What are up to?' versus on a species level."

Noticing such individuality brings a more personal angle to viewing wildlife.

"Animal personality is a hard science, but if it makes you relate to animals more, maybe people will be more interested in conserving them," said Aliperti.

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Major branches in the tree of language reconstructed

The diversity of human languages can be likened to branches on a tree. If you're reading this in English, you're on a branch that traces back to a common ancestor with Scots, which traces back to a more distant ancestor that split off into German and Dutch. Moving further in, there's the European branch that gave rise to Germanic; Celtic; Albanian; the Slavic languages; the Romance languages like Italian and Spanish; Armenian; Baltic; and Hellenic Greek. Before this branch, and some 5,000 years into human history, there's Indo-European -- a major proto-language that split into the European branch on one side, and on the other, the Indo-Iranian ancestor of modern Persian, Nepali, Bengali, Hindi, and many more.

One of the defining goals of historical linguistics is to map the ancestry of modern languages as far back as it will go -- perhaps, some linguists hope, to a single common ancestor that would constitute the trunk of the metaphorical tree. But while many thrilling connections have been suggested based on systemic comparisons of data from most of the world's languages, much of the work, which goes back as early as the 1800s, has been prone to error. Linguists are still debating over the internal structure of such well-established families as Indo-European, and over the very existence of chronologically deeper and larger families.

To test which branches hold up under the weight of scrutiny, a team of researchers associated with the Evolution of Human Languages program is using a novel technique to comb through the data and to reconstruct major branches in the linguistic tree. In two recent papers, they examine the ~5,000-year-old Indo-European family, which has been well studied, and a more tenuous, older branch known as the Altaic macrofamily, which is thought to connect the linguistic ancestors of such distant languages as Turkish, Mongolian, Korean, and Japanese.

"The deeper you want to go back in time, the less you can rely on classic methods of language comparison to find meaningful correlates," says co-author George Starostin, an Santa Fe Institute external professor based at the Higher School of Economics in Moscow. He explains that one of the major challenges when comparing across languages is distinguishing between words that have similar sounds and meanings because they might descend from a common ancestor, from those that are similar because their cultures borrowed terms from each other in the more recent past.

"We have to get to the deepest layer of language to identify its ancestry because the outer layers, they are contaminated. They get easily corrupted by replacements and borrowings," he says.

To tap into the core layers of language, Starostin's team starts with an established list of core, universal concepts from the human experience. It includes meanings like "rock," "fire," "cloud," "two," "hand," and "human," amongst 110 total concepts. Working from this list, the researchers then use classic methods of linguistic reconstruction to come up with a number of word shapes which they then match with specific meanings from the list. The approach, dubbed "onomasiological reconstruction," notably differs from traditional approaches to comparative linguistics because it focuses on finding which words were used to express a given meaning in the proto-language, rather than on reconstructing phonetic shapes of those words and associating them with a vague cloud of meanings.

Their latest re-classification of the Indo-European family, which applies the onomasiological principle and was published in the journal Linguistics, confirmed well-documented genealogies in the literature. Similar research on the Eurasian Altaic language group, whose proto-language dates back an estimated 8,000 years, confirmed a positive signal of a relationship between most major branches of Altaic -- Turkic, Mongolic, Tungusic, and Japanese. However, it failed to reproduce a previously published relationship between Korean and the other languages in the Altaic grouping. This could either mean that the new criteria were too strict or (less likely) that previous groupings were incorrect.

As the researchers test and reconstruct the branches of human language, one of the ultimate goals is to understand the evolutionary paths languages follow over generations, much like evolutionary biologists do for living organisms.

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Scientists claim that overeating is not the primary cause of obesity

Statistics from the Centers for Disease Control and Prevention (CDC) show that obesity affects more than 40% of American adults, placing them at higher risk for heart disease, stroke, type 2 diabetes, and certain types of cancer. The USDA's Dietary Guidelines for Americans 2020 -- 2025 further tells us that losing weight "requires adults to reduce the number of calories they get from foods and beverages and increase the amount expended through physical activity."

This approach to weight management is based on the century-old energy balance model which states that weight gain is caused by consuming more energy than we expend. In today's world, surrounded by highly palatable, heavily marketed, cheap processed foods, it's easy for people to eat more calories than they need, an imbalance that is further exacerbated by today's sedentary lifestyles. By this thinking, overeating, coupled with insufficient physical activity, is driving the obesity epidemic. On the other hand, despite decades of public health messaging exhorting people to eat less and exercise more, rates of obesity and obesity-related diseases have steadily risen.

The authors of "The Carbohydrate-Insulin Model: A Physiological Perspective on the Obesity Pandemic," a perspective published in The American Journal of Clinical Nutrition, point to fundamental flaws in the energy balance model, arguing that an alternate model, the carbohydrate-insulin model, better explains obesity and weight gain. Moreover, the carbohydrate-insulin model points the way to more effective, long-lasting weight management strategies.

According to lead author Dr. David Ludwig, Endocrinologist at Boston Children's Hospital and Professor at Harvard Medical School, the energy balance model doesn't help us understand the biological causes of weight gain: "During a growth spurt, for instance, adolescents may increase food intake by 1,000 calories a day. But does their overeating cause the growth spurt or does the growth spurt cause the adolescent to get hungry and overeat?"

In contrast to the energy balance model, the carbohydrate-insulin model makes a bold claim: overeating isn't the main cause of obesity. Instead, the carbohydrate-insulin model lays much of the blame for the current obesity epidemic on modern dietary patterns characterized by excessive consumption of foods with a high glycemic load: in particular, processed, rapidly digestible carbohydrates. These foods cause hormonal responses that fundamentally change our metabolism, driving fat storage, weight gain, and obesity.

When we eat highly processed carbohydrates, the body increases insulin secretion and suppresses glucagon secretion. This, in turn, signals fat cells to store more calories, leaving fewer calories available to fuel muscles and other metabolically active tissues. The brain perceives that the body isn't getting enough energy, which, in turn, leads to feelings of hunger. In addition, metabolism may slow down in the body's attempt to conserve fuel. Thus, we tend to remain hungry, even as we continue to gain excess fat.

To understand the obesity epidemic, we need to consider not only how much we're eating, but also how the foods we eat affect our hormones and metabolism. With its assertion that all calories are alike to the body, the energy balance model misses this critical piece of the puzzle.

While the carbohydrate-insulin model is not new -- its origins date to the early 1900s -- The American Journal of Clinical Nutrition perspective is the most comprehensive formulation of this model to date, authored by a team of 17 internationally recognized scientists, clinical researchers, and public health experts. Collectively, they have summarized the growing body of evidence in support of the carbohydrate-insulin model. Moreover, the authors have identified a series of testable hypotheses that distinguish the two models to guide future research.

Adoption of the carbohydrate-insulin model over the energy-balance model has radical implications for weight management and obesity treatment. Rather than urge people to eat less, a strategy which usually doesn't work in the long run, the carbohydrate-insulin model suggests another path that focuses more on what we eat. According to Dr. Ludwig, "reducing consumption of the rapidly digestible carbohydrates that flooded the food supply during the low-fat diet era lessens the underlying drive to store body fat. As a result, people may lose weight with less hunger and struggle."

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Astronomers spot the same supernova three times — and predict a fourth sighting in 16 years

An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that light from them is bent and emanated our way from numerous directions. This "gravitational lensing" effect has allowed University of Copenhagen astronomers to observe the same exploding star in three different places in the heavens. They predict that a fourth image of the same explosion will appear in the sky by 2037. The study, which has just been published in the journal Nature Astronomy, provides a unique opportunity to explore not just the supernova itself, but the expansion of our universe.

One of the most fascinating aspects of Einstein's famed theory of relativity is that gravity is no longer described as a force, but as a "curvature" of space itself. The curvature of space caused by heavy objects does not just cause planets to spin around stars, but can also bend the orbit of light beams.

The heaviest of all structures in the universe -- galaxy clusters made up of hundreds or thousands of galaxies -- can bend light from distant galaxies behind them so much that they appear to be in a completely different place than they actually are.

But that's not it: light can take several paths around a galaxy cluster, making it possible for us to get lucky and make two or more sightings of the same galaxy in different places in the sky using a powerful telescope.

Supernova déjà-vu

Some routes around a galaxy cluster are longer than others, and therefore take more time. The slower the route, the stronger the gravity; yet another astonishing consequence of relativity. This staggers the amount of time needed for light to reach us, and thereby the different images that we see.

This wondrous effect has allowed a team of astronomers at the Cosmic Dawn Center -- a basic research center run by the Niels Bohr Institute at the University of Copenhagen and DTU Space at the Technical University of Denmark -- along with their international partners, to observe a single galaxy in no less than four different places in the sky.

The observations were made using the infrared wavelength range of the Hubble Space Telescope.

By analyzing the Hubble data, researchers noted three bright light sources in a background galaxy that were evident in a previous set of observations from 2016, which disappeared when Hubble revisited the area in 2019. These three sources turned out to be several images of a single star whose life ended in a colossal explosion known as a supernova.

"A single star exploded 10 billion years ago, long before our own sun was formed. The flash of light from that explosion has just reached us," explains Associate Professor Gabriel Brammer of the Cosmic Dawn Center, who led the study with Professor Steven Rodney of the University of South Carolina.

The supernova, nicknamed "SN-Requiem," can be seen in three of the four "mirrored images" of the galaxy. Each image presents a different view of the explosive supernova's development. In the final two images, it has not yet exploded. But, by examining how galaxies are distributed within the galaxy cluster and how these images are distorted by curved space, it is actually possible to calculate how "delayed" these images are.

This has allowed astronomers to make a remarkable prediction:

"The fourth image of the galaxy is roughly 21 years behind, which should allow us to see the supernova explode one more time, sometime around 2037," explains Gabriel Brammer.

Can teach us more about the universe

Should we get to witness the SN-Requiem explosion again in 2037, it will not only confirm our understanding of gravity, but also help to shed light on another cosmological riddle that has emerged in the last few years, namely the expansion of our universe.

We know that the universe is expanding, and that different methods allow us to measure by how fast. The problem is that the various measurement methods do not all produce the same result, even when measurement uncertainties are taken into account. Could our observational techniques be flawed, or -- more interestingly -- will we need to revise our understandings of fundamental physics and cosmology?

"Understanding the structure of the universe is going to be a top priority for the main earth-based observatories and international space organizations over the next decade.Studies planned for the future will cover much of the sky and are expected to reveal dozens or even hundreds of rare gravitational lenses with supernovae like SN Requiem," Brammer elaborates:

"Accurate measurements of delays from such sources provide unique and reliable determinations of cosmic expansion and can even help reveal the properties of dark matter and dark energy."

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A recent reversal in the response of western Greenland’s ice caps to climate change

Greenland may be best known for its enormous continental scale ice sheet that soars up to 3,000 meters above sea level, whose rapid melting is a leading contributor to global sea level rise. But surrounding this massive ice sheet, which covers 79% of the world's largest island, is Greenland's rugged coastline dotted with ice capped mountainous peaks. These peripheral glaciers and ice caps are now also undergoing severe melting due to anthropogenic (human-caused) warming. However, climate warming and the loss of these ice caps may not have always gone hand-in-hand.

New collaborative research from the Woods Hole Oceanographic Institution and five partner institutions (University of Arizona, University of Washington, Pennsylvania State University, Desert Research Institute and University of Bergen), published today in Nature Geoscience, reveals that during past periods glaciers and ice caps in coastal west Greenland experienced climate conditions much different than the interior of Greenland. Over the past 2,000 years, these ice caps endured periods of warming during which they grew larger rather than shrinking.

This novel study breaks down the climate history displayed in a core taken from an ice cap off Greenland's western coast. According to the study's researchers, while ice core drilling has been ongoing in Greenland since the mid-20th century, coastal ice core studies remain extremely limited, and these new findings are providing a new perspective on climate change compared to what scientists previously understood by using ice cores from the interior portions of the Greenland ice sheet alone.

"Glaciers and ice caps are unique high-resolution repositories of Earth's climate history, and ice core analysis allows scientists to examine how environmental changes -- like shifts in precipitation patterns and global warming -- affect rates of snowfall, melting, and in turn influence ice cap growth and retreat," said Sarah Das, Associate Scientist of Geology and Geophysics at WHOI. "Looking at differences in climate change recorded across several ice core records allows us to compare and contrast the climate history and ice response across different regions of the Arctic." However, during the course of this study, it also became clear that many of these coastal ice caps are now melting so substantially that these incredible archives are in great peril of disappearing forever.

Due to the challenging nature of studying and accessing these ice caps, this team was the first to do such work, centering their study, which began in 2015, around a core collected from the Nuussuaq Peninsula in Greenland. This single core offers insight into how coastal climate conditions and ice cap changes covaried during the last 2,000 years, due to tracked changes in its chemical composition and the amount of snowfall archived year after year in the core. Through their analysis, investigators found that during periods of past warming, ice caps were growing rather than melting, contradicting what we see in the present day.

"Currently, we know Greenland's ice caps are melting due to warming, further contributing to sea level rise. But, we have yet to explore how these ice caps have changed in the past due to changes in climate," said Matthew Osman, postdoctoral research associate at the University of Arizona and a 2019 graduate of the MIT-WHOI Joint program. "The findings of this study were a surprise because we see that there is an ongoing shift in the fundamental response of these ice caps to climate: today, they're disappearing, but in the past, within small degrees of warming, they actually tended to grow."

According to Das and Osman, this phenomenon happens because of a "tug-of-war" between what causes an ice cap to grow (increased precipitation) or recede (increased melting) during periods of warming. Today, scientists observe melting rates that are outpacing the rate of annual snowfall atop ice caps. However, in past centuries these ice caps would expand due to increased levels of precipitation brought about by warmer temperatures. The difference between the past and present is the severity of modern anthropogenic warming.

The team gathered this data by drilling through an ice cap on top of one of the higher peaks of the Nuussuaq Peninsula. The entire core, about 140 meters in length, took about a week to retrieve. They then brought the meter-long pieces of core to the National Science Foundation Ice Core Facility in Denver, Colorado, and stored at -20 degrees Celsius. The core pieces were then analyzed by their layers for melt features and trace chemistry at the Desert Research Institute in Reno, Nevada. By looking at different properties of the core's chemical content, such as parts per billion of lead and sulfur, investigators were able to accurately date the core by combining these measurements with a model of past glacier flow.

"These model estimates of ice cap flow, coupled with the actual ages that we have from this high precision chemistry, help us outline changes in ice cap growth over time. This method provides a new way of understanding past ice cap changes and how that is correlated with climate," said Das. "Because we're collecting a climate record from the coast, we're able to document for the first time that there were these large shifts in temperature, snowfall and melt over the last 2,000 years, showing much more variability than is observed in records from the interior of Greenland," Das added.

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Transforming marine biodiversity discovery and monitoring

A new system for sampling fragments of DNA from marine organisms drifting in the ocean is set to create new opportunities for research on biodiversity and ways of supporting conservation activities.

Over the past decade biodiversity researchers have increasingly used DNA sequences extracted from environmental samples such as soil, marine and fresh water, and even air -- termed environmental DNA (eDNA) -- to identify the organisms present in a huge range of habitats.

Sequencing these tiny traces of DNA has proved to be a powerful technique for detecting elusive species that may only rarely be observed directly, or in early life stage, when they may be difficult to identify, revolutionising biodiversity discovery and monitoring.

Researchers from the University of Leeds and University of Milano-Bicocca in Italy have developed an innovative new approach for collecting marine eDNA samples which promises to open up biodiversity monitoring of remote offshore ocean locations.

The team has developed a novel system for easy sampling that can be deployed from ocean-going ferries and other commercial vessels such as container ships, allowing the possibility of using the global commercial shipping fleet to help monitor marine biodiversity.

Although DNA sequencing is becoming more cost-effective every year, the biggest challenge is often collecting samples over the large geographic areas needed to scale up these new monitoring techniques to a global reach.

Sampling marine eDNA far from land usually depends on access to dedicated research vessels, which are complex and expensive to operate. These logistical constraints limit the geographic scope and frequency of surveys, impeding the expansion of large scale eDNA surveys.

The new system does not require complex equipment deployed from a ship; water is collected from the engine cooling system with simple apparatus and can be carried out by non-specialists. Since commercial vessels regularly cross remote corners of most of the world's oceans, they could provide almost limitless opportunities for sample collection to contribute to biodiversity monitoring programmes.

The team collaborated with the company Corsica-Sardinia Ferries, which supports a long-term visual survey programme for cetaceans run by ISPRA (Italian Institute for Environmental Protection and Research; also a partner in the current study), to test the system, on their route between Livorno in Tuscany, and Golfo Aranci in Sardinia.

The results showed the ferry-collected samples had traces of DNA from all parts of the vertebrate ecosystem, ranging from small prey fish at the base of the food chain, such as anchovies and sardines, through small and larger predatory fish such as tuna and swordfish, all the way to dolphins, and ocean giants including fin and sperm whales.

Co-lead author Dr Simon Goodman, from the School of Biology, University of Leeds, is co-lead author of the report, published in Frontiers in Marine Science.

He said: "When we first started to dig into the sequencing results I was astounded as to how well it had captured the structure of the vertebrate ecosystem.

"It's a really exciting result and highlights the power that eDNA has for revealing fine scale ecological variation."

One of the study leads, Dr Elena Valsecchi from the Department of Environmental and Earth Sciences, the University of Milano-Bicocca, said: "This innovative methodology applied to environmental DNA allows us to make a sort of CAT (computerized axial tomography) scan of the sea.

"Next we will be scanning multiple ferry routes in the Mediterranean in order to produce a high-resolution "image" on the state of biodiversity in our seas."

Overall eDNA from 100 unique vertebrate species were detected, with species composition proving to be a good match for that known from the Mediterranean from conventional survey techniques.

In addition, the team detected fine scale variation in species occurrence related to environmental factors, such as that the relative abundance of sequences for anchovy and sardines correlated with the different water temperatures the species are known to prefer for spawning.

Read more at Science Daily

Acoustic illusions

When listening to music, we don't just hear the notes produced by the instruments, we are also immersed in its echoes from our surroundings. Sound waves bounce back off the walls and objects around us, forming a characteristic sound effect -- a specific acoustic field. This explains why the same piece of music sounds very different when played in an old church or a modern concrete building.

Architects have long been capitalising on this fact when building, say, concert halls. However, the principle can also be transferred to other applications: objects hidden underground can be visualised by measuring how sound waves from a known source are reflected.

Active and passive manipulation

Some scientists want to go one step further and systematically manipulate the acoustic field to achieve an effect that shouldn't exist per se, given the real-life situation. For instance, they are attempting to create an illusory audio experience that tricks the listener into believing they are in a concrete building or an old church. Alternatively, objects can be made invisible by manipulating the acoustic field in such a way that the listener no longer perceives them.

Usually, the desired illusion relies on using passive methods that involve structuring the surfaces with the help of what are known as metamaterials. One way of hiding an object acoustically is to coat its surface and stop it from reflecting any sound waves. However, this approach is inflexible and usually works only within a limited frequency range, making it unsuitable for many applications.

Active methods seek to achieve the illusion by superimposing another layer of sound waves. In other words, by adding a second signal to the initial acoustic field. However, until now the scope for using this approach has also been limited, as it works only if the initial field can be predicted with some certainty.

Real-time illusion

Now the group headed by Johan Robertsson, Professor of Applied Geophysics at ETH Zurich, has worked with scientists from the University of Edinburgh to develop a new concept that significantly improves the active illusion. Led by Theodor Becker, a postdoc in Robertsson's group, and Dirk-Jan van Manen, the senior scientist who was instrumental in designing the experiments, the researchers have managed to augment the initial field in real time, as they report in the latest issue of the journal Science Advances. As a result, they can make objects disappear and they can mimic non-existent ones.

To achieve the special acoustic effects, the researchers installed a large test facility for the project in the Centre for Immersive Wave Experimentation at the Switzerland Innovation Park Zurich in Dübendorf. Specifically, this facility allows them to mask the existence of an object measuring roughly 12 centimetres or simulate an imaginary object of equal size.

The target object is enclosed in an outer ring of microphones as control sensors and an inner ring of loudspeakers as control sources. The control sensors register which external acoustic signals reach the object from the initial field. Based on these measurements, a computer then calculates which secondary sounds the control sources must produce to achieve the desired augmentation of the initial field.

Sophisticated technology

To mask the object, the control sources emit a signal that completely obliterates the sound waves reflected off the object. By contrast, to simulate an object (also known as holography), the control sources augment the initial acoustic field as if sound waves were bouncing off an object at the centre of the two rings.

For this augmentation to work, the data measured by the control sensors must be transformed instantaneously into instructions for the control sources. To control the system, the researchers therefore use field-programmable gate arrays (FPGAs) with an extremely short response time.

"Our facility allows us to manipulate the acoustic field over a frequency range of more than three and a half octaves," Robertsson says. The maximum frequency for cloaking is 8,700 Hz and 5,900 Hz for simulating. To date, the researchers have been able to manipulate the acoustic field on a surface in two dimensions. As a next step, they want to increase the process to three dimensions and extend its functional range. The system currently augments airborne sound waves. However, Robertsson explains, the new process could also produce acoustic illusions under water. He envisages a vast array of potential uses in different fields, such as sensor technology, architecture and communications, as well as in the education sector.

Read more at Science Daily

New technology designed to genetically control disease-spreading mosquitoes

Leveraging advancements in CRISPR-based genetic engineering, researchers at the University of California San Diego have created a new system that restrains populations of mosquitoes that infect millions each year with debilitating diseases.

The new precision-guided sterile insect technique, or pgSIT, alters genes linked to male fertility -- creating sterile offspring -- and female flight in Aedes aegypti, the mosquito species responsible for spreading wide-ranging diseases including dengue fever, chikungunya and Zika.

"pgSIT is a new scalable genetic control system that uses a CRISPR-based approach to engineer deployable mosquitoes that can suppress populations," said UC San Diego Biological Sciences Professor Omar Akbari. "Males don't transmit diseases so the idea is that as you release more and more sterile males, you can suppress the population without relying on harmful chemicals and insecticides."

Details of the new pgSIT are described September 10, 2021, in the journal Nature Communications.

pgSIT differs from "gene drive" systems that could suppress disease vectors by passing desired genetic alterations indefinitely from one generation to the next. Instead, pgSIT uses CRISPR to sterilize male mosquitoes and render female mosquitoes, which spread disease, as flightless. The system is self-limiting and is not predicted to persist or spread in the environment, two important safety features that should enable acceptance for this technology.

Akbari says the envisioned pgSIT system could be implemented by deploying eggs of sterile males and flightless females at target locations where mosquito-borne disease spread is occurring.

"Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, and suppress and even eliminate mosquito populations," the researchers note in the Nature Communications paper. "This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable and reversible manner."

Although molecular genetic engineering tools are new, farmers have been sterilizing male insects to protect their crops since at least the 1930s. United States growers in the 1950s began using radiation to sterilize pest species such as the New World Screwworm fly, which is known to destroy livestock. Similar radiation-based methods continue today, along with the use of insecticides. pgSIT is designed as a much more precise and scalable technology since it uses CRISPR -- not radiation or chemicals -- to alter key mosquito genes. The system is based on a method that was announced by UC San Diego in 2019 by Akbari and his colleagues in the fruit fly Drosophila.

As envisioned, Akbari says pgSIT eggs can be shipped to a location threatened by mosquito-borne disease or developed at an on-site facility that could produce the eggs for nearby deployment. Once the pgSIT eggs are released in the wild, typically at a peak rate of 100-200 pgSIT eggs per Aedes aegypti adult, sterile pgSIT males will emerge and eventually mate with females, driving down the wild population as needed.

Beyond Aedes aegypti, the researchers believe the pgSIT technology could be directed to other species that spread disease.

"… This study suggests pgSIT may be an efficient technology for mosquito population control and the first example of one suited for real-world release," the researchers say. "Going forward, pgSIT may provide an efficient, safe, scalable, and environmentally friendly alternative next-generation technology for wild population control of mosquitoes resulting in wide-scale prevention of human disease transmission."

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Environmental conditions of early humans in Europe

Understanding the environmental conditions under which early humans dispersed out of Africa is important for understanding the factors that affected human evolution. This is a topical question that remains debated. A recent study prepared in collaboration with researchers from the University of Helsinki and the Universities of Granada, Tarragona, Zaragoza, Barcelona, Salamanca, Madrid and Tübingen provides new information on the environmental context of earliest human occupation in Europe during the Pleistocene.

The research is part of the Orce project (ProyectORCE) funded by the local government of Andalucía and led by the University of Granada, in which researchers from the University of Helsinki have been participating since 2017. The project is responsible for archeological/palaentological excavations and related research in Andalucía, Spain.

The study is focussed on the Guadix-Baza Basin, Andalucía, Spain, where the researchers used dental ecometric trait distribution within fossil large mammal communities to reconstruct climatic variables and net primary production of plant communities from ca. 4.5 million years to ca. 400,000 years ago.

The Guadix-Baza basin is of particular importance for understanding early human environments outside Africa, because it includes a couple of sites that are among the earliest human occupation sites in Europe, Barranco León and Fuente Nueva 3 near the city of Orce, which have been dated at ca. 1.4 -- 1.2 million years in age.

Based on the estimates, the climate in the Guadix-Baza Basin varied from roughly similar to present (e.g. Venta Micena, ca. 1.6 million years ago) to more humid, with higher annual primary production. The early human occupation sites in the Guadix-Baza Basin, such as Barranco León and Fuente Nueva 3, tended to have higher primary production than in the region today. The vegetation was mostly similar to Mediterranean forest without significant grassy undergrowth, making it different from African grass-dominated savanna environments.

Lead author Juha Saarinen from the University of Helsinki said: "Tooth wear-based dietary analyses indicate that most of the large herbivorous mammals in these environments did not consume significant amounts of grass, further attesting to the scarcity of grassy vegetation. This is an important finding, as it suggests that already the earliest human occupation sites in Europe were often different from African grassy savannas in terms of vegetation and interactions between large mammal fauna and vegetation."

The conditions under which early members of the genus Homo dispersed outside Africa were also analysed on a broader scale, across Europe during the Early and Middle Pleistocene. The model is based on the comparison of functional trait distribution of large herbivorous mammals in sites with archaeological or fossil evidence of human presence and in sites, which lack evidence of human presence.

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