A star like a Matryoshka doll: New theory for gravastars

If gravitational condensate stars (or gravastars) actually existed, they would look similar to black holes to a distant observer. Two theoretical physicists at Goethe University Frankfurt have now found a new solution to Albert Einstein's theory of general relativity, according to which gravitational stars could be structured like a Russian matryoshka doll, with one gravastar located inside another.

The interior of black holes remains a conundrum for science.

In 1916, German physicist Karl Schwarzschild outlined a solution to Albert Einstein's equations of general relativity, according to which the center of a black hole consists of a so-called singularity, a point at which space and time no longer exist.

Here, the theory goes, all physical laws, including Einstein's general theory of relativity, no longer apply; the principle of causality is suspended.

This constitutes a great nuisance for science: after all, it means that no information can escape from a black hole beyond the so-called event horizon.

This could be a reason why Schwarzschild's solution did not attract much attention outside the theoretical realm for a long time -- that is, until the first candidate for a black hole was discovered in 1971, followed by the discovery of the black hole in the center of our Milky Way in the 2000s, and finally the first image of a black hole, captured by the Event Horizon Telescope Collaboration in 2019.

In 2001, Pawel Mazur and Emil Mottola proposed a different solution to Einstein's field equations that led to objects which they called gravitational condensate stars, or gravastars.

Contrary to black holes, gravastars have several advantages from a theoretical astrophysics perspective.

On the one hand, they are almost as compact as black holes and also exhibit a gravity at their surface that is essentially as strong as that of a black hole, hence resembling a black hole for all practical purposes.

On the other hand, gravastars do not have an event horizon, that is, a boundary from within which no information can be sent out, and their core does not contain a singularity.

Instead, the center of gravastars is made up of an exotic -- dark -- energy that exerts a negative pressure to the enormous gravitational force compressing the star.

The surface of gravastars is represented by a wafer-thin skin of ordinary matter, the thickness of which approaches zero.

Theoretical physicists Daniel Jampolski and Prof. Luciano Rezzolla of Goethe University Frankfurt have now presented a solution to the field equations of general relativity that describes the existence of a gravastar inside another gravastar.

They have given this hypothetical celestial object the name "nestar" (from the English "nested").

Daniel Jampolski, who discovered the solution as part of his Bachelor's thesis supervised by Luciano Rezzolla, says: "The nestar is like a matryoshka doll," adding that, "our solution to the field equations allows for a whole series of nested gravastars." Whereas Mazur and Mottola posit that the gravastar has a near infinite thin skin consisting of normal matter, the nestar's matter-composed shell is somewhat thicker: "It's a little easier to imagine that something like this could exist."

Read more at Science Daily

Early-stage subduction invasion

Our planet's lithosphere is broken into several tectonic plates. Their configuration is ever-shifting, as supercontinents are assembled and broken up, and oceans form, grow, and then start to close in what is known as the Wilson cycle.

In the Wilson cycle, when a supercontinent like Pangea is broken up, an interior ocean is formed.

In the case of Pangea, the interior ocean is the Atlantic. This ocean has a rift in the middle, and passive margins on the side, which means no seismic or volcanic activity occurs along its shores.

Destined to keep expanding, an Atlantic-type ocean will eventually become the exterior ocean of the next supercontinent.

Currently, Earth's exterior ocean is the Pacific. The Pacific also has a rift in the middle, but it is bounded by subduction zones and thus will eventually close.

Along its margins, earthquakes and eruptions abound -- a pattern known as the ring of fire.

The ocean-closing phase of each Wilson cycle requires the transition from passive to active (subducting) margins at the edges of the interior ocean.

The oceanic crust along the coast of the Atlantic is old and heavy, so it is primed to subduct, but before it can do so, it must break and bend.

The only force in nature that can break oceanic plates like these is slab pull from another subduction zone.

But this doesn't happen spontaneously. So how does subduction initiate around interior oceans?

There currently are two subduction zones in the Atlantic: the Lesser Antilles and Scotia.

But neither of them formed spontaneously in the Atlantic; they were forced by subduction zones in the Pacific during the Cretaceous and then propagated along transform margins, where the continent is narrow and there is barely a land bridge.

They jumped oceans.

Today, on the eastern shore of the Atlantic, in Gibraltar, we have the opportunity to observe the very earliest stages of this process, known as subduction invasion, while the jump occurs from a different basin -- in this case, the Mediterranean.

This is an incredibly valuable opportunity because the chances of observing the very start of any given tectonic process are limited.

And subduction initiation is difficult to observe because it leaves almost no traces behind.

Once subduction starts, it erases the record of its initial stages; the subducted plate ends up in the mantle, never to be exposed at the surface again (except in the rare case of ophiolites).

The activity of the Gibraltar subduction zone in the Mediterranean has been hotly debated.

The Gibraltar arc formed in the Oligocene as a part of the Western Mediterranean subduction zones.

While we can see a subducted plate in the mantle underneath it, almost no further movement is currently happening.

A new paper by Duarte et al., just published in Geology, suggests that Gibraltar is active -- it is just currently experiencing a slow movement phase because the subducting slab is very narrow, and it is trying to pull down the entire Atlantic plate.

"[These are] some of the oldest pieces of crust on Earth, super strong and rigid -- if it were any younger, the subducting plate would just break off and subduction would come to a halt," explains Duarte.

"Still, it is just barely strong enough to make it, and thus moves very slowly."

A new computational, gravity-driven 3-D model, developed by the authors, shows that this slow phase will last for another 20 million years.

After that, the Gibraltar subduction zone will invade the Atlantic Ocean and accelerate.

That will be the beginning of the recycling of crust on the eastern side of the Atlantic, and might be the start of the Atlantic itself beginning to close, initiating a new phase in the Wilson cycle.

Broadly, this study shows that subduction invasion, the process whereby a new subduction zone forms in an exterior ocean and then migrates to an interior ocean, is likely a common mechanism of subduction initiation in Atlantic-type oceans, and thus plays a key role in the geological evolution of our planet.

Locally, the finding that the Gibraltar subduction is still currently active has important implications for seismic activity in the area.

Recurrence intervals are expected to be very long during this slow phase, but the potential for high-magnitude events, such as the 1755 Lisbon earthquake, remains and requires preparedness.

Read more at Science Daily

Discovery of new Li ion conductor unlocks new direction for sustainable batteries

One of the grand challenges for materials science is the design and discovery of new materials that address global priorities such as Net Zero.

In a paper published in the journal Science, researchers at the University of Liverpool have discovered a solid material that rapidly conducts lithium ions.

Such lithium electrolytes are essential components in the rechargeable batteries that power electric vehicles and many electronic devices.

Consisting of non-toxic earth-abundant elements, the new material has high enough Li ion conductivity to replace the liquid electrolytes in current Li ion battery technology, improving safety and energy capacity.

Using a transformative scientific approach to design the material, the interdisciplinary research team from the University synthesised the material in the laboratory, determined its structure (the arrangement of the atoms in space) and demonstrated it in a battery cell.

The new material is one of a very small number of solid materials that achieve Li ion conductivity high enough to replace liquid electrolytes, and operates in a new way because of its structure.

Its discovery was achieved through a collaborative computational and experimental workflow that used AI and physics-based calculations to support decisions made by chemistry experts at the University.

The new material provides a platform for the optimisation of chemistry to further enhance the properties of the material itself, and to identify other materials based on the new understanding provided by the study.

Professor Matt Rosseinsky, from the University of Liverpool's Department of Chemistry, said: "This research demonstrates the design and discovery of a material that is both new and functional. The structure of this material changes previous understanding of what a high-performance solid-state electrolyte looks like.

"Specifically, solids with many different environments for the mobile ions can perform very well, not just the small number of solids where there is a very narrow range of ionic environments. This dramatically opens up the chemical space available for further discoveries.

Recent reports and media coverage herald the use of AI tools to find potentially new materials.

In these cases, the AI tools are working independently and thus are likely to recreate what they were trained on in various ways, generating materials that may be very similar to known ones.

"This discovery research paper shows that AI and computers marshalled by experts can tackle the complex problem of real-world materials discovery, where we seek meaningful differences in composition and structure whose impact on properties is assessed based on understanding."

"Our disruptive design approach offers a new route to discovery of these and other high-performance materials that rely on the fast motion of ions in solids."

Read more at Science Daily

Evidence of geothermal activity within icy dwarf planets

A team co-led by Southwest Research Institute found evidence for hydrothermal or metamorphic activity within the icy dwarf planets Eris and Makemake, located in the Kuiper Belt. Methane detected on their surfaces has the tell-tale signs of warm or even hot geochemistry in their rocky cores, which is markedly different than the signature of methane from a comet.

"We see some interesting signs of hot times in cool places," said SwRI's Dr. Christopher Glein, an expert in planetary geochemistry and lead author of a paper about this discovery.

The Kuiper Belt is a vast donut-shaped region of icy bodies beyond the orbit of Neptune at the edge of the solar system.

Eris and Makemake are comparable in size to Pluto and its moon Charon.

These bodies likely formed early in the history of our solar system, about 4.5 billion years ago.

Far from the heat of our Sun, KBOs were believed to be cold, dead objects.

Newly published work from JWST studies made the first observations of isotopic molecules on the surfaces of Eris and Makemake.

These so-called isotopologues are molecules that contain atoms having a different number of neutrons.

They provide data that are useful in understanding planetary evolution.

The JWST team measured the composition of the dwarf planets' surfaces, particularly the deuterium (heavy hydrogen, D) to hydrogen (H) ratio in methane.

Deuterium is believed to have formed in the Big Bang, and hydrogen is the most abundant nucleus in the universe.

The D/H ratio on a planetary body yields information about the origin, geologic history and formation pathways of compounds containing hydrogen.

"The moderate D/H ratio we observed with JWST belies the presence of primordial methane on an ancient surface. Primordial methane would have a much higher D/H ratio," Glein said.

"Instead, the D/H ratio points to geochemical origins for methane produced in the deep interior. The D/H ratio is like a window. We can use it in a sense to peer into the subsurface. Our data suggest elevated temperatures in the rocky cores of these worlds so that methane can be cooked up. Molecular nitrogen (N2) could be produced as well, and we see it on Eris. Hot cores could also point to potential sources of liquid water beneath their icy surfaces."

Over the past two decades, scientists have learned that icy worlds can be much more internally evolved than once believed.

Evidence for subsurface oceans has been found at several icy moons such as Saturn's moon Enceladus and Jupiter's moon Europa.

Liquid water is one of the key ingredients in determining potential planetary habitability.

The possibility of water oceans inside Eris and Makemake is something that scientists are going to study in the years ahead.

If either of them is habitable, then it would become the most distant world in the solar system that could possibly support life.

Finding chemical indicators of internally driven processes takes them a step in this direction.

"If Eris and Makemake hosted, or perhaps could still host warm, or even hot, geochemistry in their rocky cores, cryovolcanic processes could then deliver methane to the surfaces of these planets, perhaps in geologically recent times," said Dr. Will Grundy, an astronomer at Lowell Observatory, one of Glein's co-authors and lead author of a companion paper.

"We found a carbon isotope ratio (13C/12C) that suggests relatively recent resurfacing."

This work is part of a paradigm shift in planetary science. It is increasingly being recognized that cold, icy worlds may be warm at heart.

Models developed for this study additionally point to the formation of geothermal gases on Saturn's moon Titan, which also has abundant methane.

Furthermore, the inference of unexpected activity on Eris and Makemake underscores the importance of internal processes in shaping what we see on large KBOs and is consistent with findings at Pluto.

Read more at Science Daily

New 'time travel' study reveals future impact of climate change on coastal marshes

A new Tulane University study published in Nature Communications offers a glimpse into the possible impact of climate change on coastal wetlands 50 years or longer into the future.

Scientists are usually forced to rely on computer models to project the long-term effects of rising seas.

But an unexpected set of circumstances enabled a real-world experiment along the Gulf Coast.

An extensive network of nearly 400 monitoring sites was established along the Louisiana coast after hurricanes Katrina and Rita.

Then the rate of sea-level rise in the region surged to more than 10 millimeters (half an inch) per year -- at least three times the global average.

That exposed the region to the kind of ocean rise not expected until around 2070.

The accelerated rise created a unique opportunity to determine whether the marshes can survive that pace of coastal flooding.

"It is the dream of every field researcher who does experiments -- we can basically travel 50 years into the future to get a peek at what's in store," said Torbjörn Törnqvist, Vokes Geology Professor in the Tulane Department of Earth and Environmental Sciences.

The researchers used new techniques developed by European scientists to measure sea-level rise right off the coast with satellite data, something that was previously not available.

The team then compared the rate of water-level rise at each monitoring site with the rate of wetland elevation change determined by other instruments and found that almost 90% of the sites were in deficit.

"To our knowledge, this is the first time that a climate impact experiment has been carried out over a region this large, based on hundreds of monitoring stations that have collected data for about 15 years," said Guandong Li, a PhD candidate in Earth and Environmental Sciences at Tulane who led the study.

"This has also allowed us to study the climate impact on a heavily human-influenced landscape, rather than a more resilient pristine ecosystem."

Li was investigating the role of land subsidence in coastal Louisiana when a team led by Sönke Dangendorf, the David and Jane Flowerree Professor in Tulane's Department of River-Coastal Science and Engineering, demonstrated the unprecedented rates of sea-level rise along the Gulf and Southeast U.S. coasts since 2010.

"Guandong immediately dropped everything he was working on to take advantage of this unique opportunity," Törnqvist said.

"He set out to answer the key question of whether coastal marshes can keep up with this rate of sea-level rise, as some earlier modeling studies had suggested they can."

If the current climate scenario persists, the rate of sea-level rise by 2070 is expected to be about 7 millimeters (one quarter inch) per year.

The study projects that approximately 75% of wetland sites will be in deficit by that time, potentially resulting in a rate of wetland loss much higher than what has already occurred in the past century.

However, the researchers emphasize that there is hope for a more favorable outcome if immediate action is taken.

By meeting the targets set by the Paris Agreement and reducing carbon emissions, it is possible to shift to a more sustainable climate trajectory that would reduce the rate of wetland loss.

Read more at Science Daily

Reforestation programs could threaten vast area of tropical grasslands

New research led by the University of Liverpool reveals the scale of inappropriate reforestation projects across Africa.

A study published in the journal Science reveals that an area the size of France is under threat by forest restoration initiatives due to inappropriate restoration in the form of tree-planting.

Researchers analysed the areas of land committed to restoration via reforestation and found that many programmes include areas classified as non-forest systems.

They believe that the inclusion of non-forest systems such as savannas and grasslands, which are threatened by increased tree cover, is the key issue.

They warn that planting trees in these grassy areas, which are structurally, functionally and compositionally distinct from forests, could be a risk to wildlife such as rhinos and wildebeest, as well as people who depend on these ecosystems.

Kate Parr, Professor of Tropical Ecology at the University's School of Environmental Sciences and author of the study, said: "Restoration of ecosystems is needed and important, but it must be done in a way that is appropriate to each system.

"Non-forest systems such as savannas are misclassified as forest and therefore considered in need of restoration with trees.

"There is an urgent need to revise definitions so that savannas are not confused with forest because increasing trees is a threat to the integrity and persistence of savannas and grasslands."

"Highlighting this issue now means there is still time to negate this threat and ensure that non-forest systems receive appropriate restoration."

Dr Nicola Stevens, Trapnell Research Fellow in African Environments at the University of Oxford and co-author of the paper said: "The urgency of implementing large-scale tree planting is prompting funding of inadequately assessed projects that will most likely have negligible sequestration benefits and cause potential social and ecological harm."

The study highlights that the issues raised are not unique to Africa and many other non-forest areas, for example the open savannas and grasslands of India and Brazil, could face a similar future due to inappropriate 'restoration' with trees.

Read more at Science Daily

Ancient retroviruses played a key role in the evolution of vertebrate brains

Researchers report February 15 in the journal Cell that ancient viruses may be to thank for myelin -- and, by extension, our large, complex brains. The team found that a retrovirus-derived genetic element or "retrotransposon" is essential for myelin production in mammals, amphibians, and fish. The gene sequence, which they dubbed "RetroMyelin," is likely a result of ancient viral infection, and comparisons of RetroMyelin in mammals, amphibians, and fish suggest that retroviral infection and genome-invasion events occurred separately in each of these groups.

"Retroviruses were required for vertebrate evolution to take off," says senior author and neuroscientist Robin Franklin of Altos Labs-Cambridge Institute of Science.

"If we didn't have retroviruses sticking their sequences into the vertebrate genome, then myelination wouldn't have happened, and without myelination, the whole diversity of vertebrates as we know it would never have happened."

Myelin is a complex, fatty tissue that ensheathes vertebrate nerve axons.

It enables rapid impulse conduction without needing to increase axonal diameter, which means nerves can be packed closer together.

It also provides metabolic support to nerves, which means nerves can be longer.

Myelin first appeared in the tree of life around the same time as jaws, and its importance in vertebrate evolution has long been recognized, but until now, it was unclear what molecular mechanisms triggered its appearance.

The researchers noticed RetroMyelin's role in myelin production when they were examining the gene networks utilized by oligodendrocytes, the cells that produce myelin in the central nervous system.

Specifically, the team was investigating the role of noncoding regions including retrotransposons in these gene networks -- something that hasn't previously been explored in the context of myelin biology.

"Retrotransposons compose about 40% of our genomes, but nothing is known about how they might have helped animals acquire specific characteristics during evolution," says first author Tanay Ghosh, a computational biologist at Altos Labs-Cambridge Institute of Science.

"Our motivation was to know how these molecules are helping evolutionary processes, specifically in the context of myelination."

In rodents, the researchers found that the RNA transcript of RetroMyelin regulates the expression of myelin basic protein, one of the key components of myelin.

When they experimentally inhibited RetroMyelin in oligodendrocytes and oligodendrocyte progenitor cells (the stem cells from which oligodendrocytes are derived), the cells could no longer produce myelin basic protein.

To examine whether RetroMyelin is present in other vertebrate species, the team searched for similar sequences within the genomes of jawed vertebrates, jawless vertebrates, and several invertebrate species.

They identified analogous sequences in all other classes of jawed vertebrates (birds, fish, reptiles, and amphibians) but did not find a similar sequence in jawless vertebrates or invertebrates.

"There's been an evolutionary drive to make impulse conduction of our axons quicker because having quicker impulse conduction means you can catch things or flee from things more rapidly," says Franklin.

Next, the researchers wanted to know whether RetroMyelin was incorporated once into the ancestor of all jawed vertebrates or whether there were separate retroviral invasions in the different branches.

To answer these questions, they constructed a phylogenetic tree from 22 jawed vertebrate species and compared their RetroMyelin sequences.

The analysis revealed that RetroMyelin sequences were more similar within than between species, which suggests that RetroMyelin was acquired multiple times through the process of convergent evolution.

The team also showed that RetroMyelin plays a functional role in myelination in fish and amphibians.

When they experimentally disrupted the RetroMyelin gene sequence in the fertilized eggs of zebrafish and frogs, they found that the developing fish and tadpoles produced significantly less myelin than usual.

Read more at Science Daily

Diverse ancient volcanoes on Mars discovered by planetary scientist may hold clues to pre-plate tectonic activity on Earth

Volcanoes are a common feature on the surfaces of solid planets within the solar system, resulting from magmatic activity occurring within the planetary crust. On Earth, volcanism is driven primarily by heat and crustal recycling associated with plate tectonics, but Mars lacks plate tectonics and the driver of volcanism is not well understood.

Recent research by Professor Joseph MICHALSKI, a geologist in the Department of Earth Sciences at The University of Hong Kong (HKU), has revealed intriguing insights into the volcanic activity on Mars.

He proposes that Mars has significantly more diverse volcanism than previously realised, driven by an early form of crust recycling called vertical tectonics.

The findings, recently published in Nature Astronomy, shed light on the ancient crust of Mars and its potential implications for understanding early crustal recycling on both Mars and Earth.

Traditionally, Mars has been known to have large shield volcanoes similar to those in Hawaii.

However, it was not known that Mars also possessed the diverse, explosive volcanoes that form on Earth due to crustal recycling.

The recent research conducted by Professor Michalski and his international team discover a vast number of diverse volcanoes in the ancient crust of Mars.

'We have known for decades that Mars has volcanoes, but most of the recognised volcanoes correspond to large basaltic shield volcanoes similar to the ones that make up Hawaii,' he explains.

'In this work, we show that the ancient crust has many other types of volcanoes such as lava domes, stratovolcanoes, calderas and large shields of ash, not lava.

Further, most scientists see Mars as a planet composed of basalt, which has low silica content and represents little crustal evolution, but these volcanoes have high silica content which means they formed from a complex process of magma evolution not known before.'

The paper suggests that intense volcanism occurred on ancient Mars, causing the crust to collapse into the mantle, where the rocks re-melted, resulting in magmas that have high silica.

This tectonic process, called vertical tectonics, is hypothesised to have occurred on the ancient Earth, but rocks on Earth from that period (the Archean, more than 3 billion years ago) are highly modified by later geological activity, so we cannot see evidence for this process clearly on this planet.

Therefore, exploring other planets like Mars, which has volcanism but no plate tectonics, can help reveal the mysteries of early crustal recycling on both the Red Planet, and by analogy, on early Earth.

Professor Michalski concluded, 'Mars contains critical geological puzzle pieces that help us understand not only that planet, but the Earth as well.

Martian volcanism is much more complex and diverse than has been previously thought.'

Read more at Science Daily

New study points to more climate extremes

A new study has found similarities between long-term climatic changes in South Australia and temperate agricultural areas in Argentina -- highlighting similarities across these Southern Hemisphere countries.

As temperature records tumble, and the threat of bushfires and dry conditions looms large, an international study by Flinders University and Argentinian researchers renews the urgency of calls to make more concerted efforts to prepare for climate extremes in South Australia.

Highs and lows in temperature and rainfall indices over the past 50 years have shown an increase in maximum and minimum temperatures of 1.1°C and 0.7°C and less precipitation while pointing to more intense and extended drought periods, extreme summer heatwaves alongside occasional extremes such as frost and flood.

South Australia -- often cited as the driest state on the driest continent -- is poised to see more weather extremes in temperature and precipitation with more storm events, longer and more severe droughts and higher temperature peaks up to 3-5°C above current averages likely to follow global trends, the study shows.

"We found remarkable warming signal trends in both hot and cold extreme weather events," says Universidad Nacional del Sur researcher Dr Federico Ferrelli in a new article supported by Argentina's National Scientific and Technical Research Council.

"This reminds us that we need to focus on climate change mitigation and adapt sustainable management plans to better buffer ecosystems and human health and wellbeing, particularly in areas most exposed to these extreme weather patterns."

Flinders University co-author Professor Patrick Hesp, an expert in coastal dune systems, says that if SA's rainfall continue to decline according to such forecasts, "we can expect to see increased soil erosion in dryland agricultural regions and greater mobility of coastal dune systems -- especially on western coast areas where mean annual rainfall is already quite low."

The researchers used 24 climate extreme indices based on Bureau of Meteorology data to find a significant increase in extreme hot events -- including summer days and tropical night temperatures -- as well as daily maximum and daily minimum temperatures.

While cold indices such as frost days show negative trends, heavy and extreme storms have become more severe locally while rain decreases regionally.

Land management practices, including less land clearance, native plant revegetation and more sustainable agricultural practices, is one step in the right direction.

While Argentina and Australia are economically different countries, the researchers emphasise that the imminent impacts of climate change are reflected in both temperate climate zones in the Southern Hemisphere and impacting on a global scale.

For instance, the Pampas Region in Argentina has experienced substantial increases in maximum, minimum and mean temperatures (1.8 °C, 1.2 °C, and 1.2 °C respectively), with some areas affected by falling precipitation and rising aridity.

"Therefore it is imperative to develop sustainable land management policies to address these issues," researchers say.

"Global warming effects ecosystems, biodiversity, agriculture and food security, water resources, and human health and wellbeing.

"It also contributes to economic and social inequities as vulnerable populations and developing countries are often the hardest hit by the effects of climate change."

Including SA's rising 1.8 million population, extreme temperatures could severely impact cardiovascular and respiratory diseases, vector-borne diseases and affect mortality rates, the researchers warn.

Read more at Science Daily

Anthropologists' research unveils early stone plaza in the Andes

Two University of Wyoming anthropology professors have discovered one of the earliest circular plazas in Andean South America, showcasing monumental megalithic architecture, which refers to construction that uses large stones placed upright with no mortar.

Located at the Callacpuma archaeological site in the Cajamarca Basin of northern Peru, the plaza is built with large, vertically placed megalithic stones -- a construction method previously unseen in the Andes.

Associate Professor Jason Toohey, project lead, and Professor Melissa Murphy have been researching this topic since the project's inception in 2015.

Excavations took place in the plaza starting in 2018.

Their paper, which reports new data on this earliest known megalithic circular plaza in the northern Andes, is titled "A Monumental Stone Plaza at 4750 BP in the Cajamarca Valley of Peru" and has been published today (Feb.

14) in the peer-reviewed journal Science Advances.

Radiocarbon dating places its initial construction around 4,750 years ago during the Late Preceramic Period, making it one of the earliest instances of such architecture in the Americas.

To better understand this timeline, the team carefully excavated within the plaza, uncovering artifacts related to life in the past and collecting charcoal samples for dating.

All material remains then were cleaned, processed and analyzed in the laboratory.

"This structure was built approximately 100 years before the Great Pyramids of Egypt and around the same time as Stonehenge," Toohey says.

These dates signify that the circular plaza at Callacpuma is the earliest known example of monumental and megalithic architecture in the Cajamarca Valley -- and one of the earliest examples in ancient Peru.

"It was probably a gathering place and ceremonial location for some of the earliest people living in this part of the Cajamarca Valley," Toohey adds.

"These people were living a primarily hunting-and-gathering lifestyle and probably had only recently begun growing crops and domesticating animals."

The plaza is formed by two concentric walls and measures about 60 feet in diameter.

The project is led by Toohey and Patricia Chirinos Ogata from the University of California-Santa Barbara.

The team also includes Murphy, as well as undergraduate and graduate students from Peru and the U.S.

Toohey is an anthropological archaeologist who is dedicated to taking a holistic and multidisciplinary approach to the field.

He has conducted fieldwork in the Peruvian Andes since 2003.

The department head for anthropology at UW, Murphy is a biological anthropologist specializing in bioarchaeology and committed to multidisciplinary approaches within anthropology.

Read more at Science Daily

The brain is 'programmed' for learning from people we like

Our brains are "programmed" to learn more from people we like -- and less from those we dislike. This has been shown by researchers in cognitive neuroscience in a series of experiments.

Memory serves a vital function, enabling us to learn from new experiences and update existing knowledge.

We learn both from individual experiences and from connecting them to draw new conclusions about the world.

This way, we can make inferences about things that we don't necessarily have direct experience of. This is called memory integration and makes learning quick and flexible.

Inês Bramão, associate professor of psychology at Lund University, provides an example of memory integration: Say you're walking in a park.

You see a man with a dog. A few hours later, you see the dog in the city with a woman.

Your brain quickly makes the connection that the man and woman are a couple even though you have never seen them together.

"Making such inferences is adaptive and helpful. But of course, there's a risk that our brain draws incorrect conclusions or remembers selectively," says Inês Bramão.

Important who provides the information

To examine what affects our ability to learn and make inferences, Inês Bramão, along with colleagues Marius Boeltzig and Mikael Johansson, set up experiments where participants were tasked with remembering and connecting different objects.

It could be a bowl, ball, spoon, scissors, or other everyday objects.

It turned out that memory integration, i.e., the ability to remember and connect information across learning events, was influenced by who presented it. If it was a person the participant liked, connecting the information was easier compared to when the information came from someone the participant disliked.

The participants provided individual definitions of 'like' and 'dislike' based on aspects such as political views, major, eating habits, favorite sports, hobbies, and music.

Can be translated to politics

The findings can be applied in real life, according to the researchers.

Inês Bramão takes a hypothetical example from politics:

"A political party argues for raising taxes to benefit healthcare. Later, you visit a healthcare center and notice improvements have been made. If you sympathize with the party that wanted to improve healthcare through higher taxes, you're likely to attribute the improvements to the tax increase, even though the improvements might have had a completely different cause."

About fundamental mechanisms

There's already vast research describing that people learn information differently depending on the source and how that characterizes polarization and knowledge resistance.

"What our research shows is how these significant phenomena can partly be traced back to fundamental principles that govern how our memory works," says Mikael Johansson, professor of psychology at Lund University.

We are more inclined to form new connections and update knowledge from information presented by groups we favor.

Innate way of handling information

Understanding the roots of polarization, resistance to new knowledge, and related phenomena from basic brain functions offers a deeper insight into these complex behaviors, the researchers argue.

So, it's not just about filter bubbles on social media but also about an innate way of assimilating information.

Read more at Science Daily

Low-cost microbe can speed biological discovery

Cornell University researchers have created a new version of a microbe to compete economically with E. coli -- a bacteria commonly used as a research tool due to its ability to synthesize proteins -- to conduct low-cost and scalable synthetic biological experiments.

As an inexpensive multiplier -- much like having a photocopier in a test tube -- the bacteria Vibrio natriegens could help labs test protein variants for creation of pharmaceuticals, synthetic fuels and sustainable compounds that battle weeds or pests.

The microbe can work effectively without costly incubators, shakers or deep freezers and can be engineered within hours.

The research publishes Feb. 13 in PNAS Nexus.

"It's really easy to produce," said lead author David Specht, a postdoctoral researcher in the laboratory ofBuz Barstow, assistant professor of biological and environmental engineering.

To study proteins for creating medical cures or fashioning fuels, researchers use a plasmid (a small piece of DNA) that acts as the instruction manual to make the molecular machine -- a protein -- of interest.

Currently, when researchers place a plasmid into E. coli, they can create many copies to test several variants.

E. coli cells help molecular biologists multiply and manipulate plasmids for protein engineering, but the process is expensive since they often purchase the bacteria from manufacturers, must keep it cold and maintain rooms of expensive equipment to sustain it. A modified E. coli, used for this purpose, is also very fragile.

"As scientists, we don't often know precisely what those regulatory or molecular sequences should be to achieve our goals," said Barstow.

"So, we must test a lot of variants, and Vibrio natriegens allows researchers to scale up that process of testing."

The microbe V. natriegens is not complicated, Specht said. "It's so simple to make that someone with limited resources -- like high school labs, home inventors or startup biological businesses -- can do it," he said.

Researcher Timothy Sheppard compared the simplicity of V. natriegens in conducting synthetic and molecular experiments to using a simple writing instrument hundreds of years old: "We've found nature's pencil for cloning and conducting synthetic biology," he said.

The process is inexpensive with V. natriegens, as it requires no capital equipment purchases and it can work at room temperature.

The cells produced from V. natriegens grow quickly: According to the paper, a transformation started at 9 a.m. yields visible colonies by 5 p.m., each filled with masses of proteins.

Read more at Science Daily

Greenland's ice sheet is melting -- and being replaced by vegetation

An estimated 11,000 sq miles or 28,707 sq kilometres of Greenland's ice sheet and glaciers have melted over the last three decades, according to a major analysis of historic satellite records.

The total area of ice loss is equivalent to the size of Albania, and represents about 1.6 % of Greenland's total ice and glacier cover.

Where there was once ice and snow, there is now barren rock, wetlands and areas of shrub.

A team of scientists from the University of Leeds, who have tracked the changes across Greenland from the 1980s through to the 2010s, say warmer air temperatures are causing the ice to retreat, which in turn is having an impact on the temperature of the land surface, greenhouse gas emissions and the stability of the landscape.

Permafrost -- a permanently frozen layer below the Earth's surface -- is being "degraded" by the warming and in some areas, the scientists warn that it could have an impact on the infrastructure, buildings and communities that exist above it.

Their findings -- "Land cover changes across Greenland dominated by a doubling of vegetation in three decades"- are reported today (13/02) in the journal Scientific Reports.

Impact of global warming

Greenland is part of the Arctic region. It is the world's biggest island, around 836,330 sq miles in size (2.1 million sq km). Most of the land is covered by ice and glaciers and it is home to almost 57,000 people.

Since the 1970s, the region has been warming at double the global mean rate. On Greenland, average annual air temperatures between 2007 and 2012 were 3 degrees C warmer, compared with the 1979 to 2000 average.

And the researchers warn that more extreme temperatures are likely in the future.

Jonathan Carrivick, an Earth scientist based in the Faculty of Environment at Leeds and one of the authors of the study, said: "Warmer temperatures are linked to the land cover changes that we are seeing on Greenland.

"By analysing high resolution satellite images, we have been able to produce a detailed record of the land cover changes that are taking place."

Ice disappears to be replaced by bare rock and shrubs

Ice loss was concentrated around the edges of present-day glaciers but also in the north and south- west of Greenland. There were also high-levels of ice loss in localised areas in the west, mid-north-west and south-east.

Over the three decades, the amount of land with vegetation growing on it increased by 33,774 sq miles (87,475 sq km), more than doubling over the study period.

A pronounced increase in vegetation was seen across the south-west, east and north-east. The greatest increase in dense wetland vegetation occurred in the vicinity of Kangerlussuaq in the south-west and in isolated areas in the north-east.

Analysis by the researchers revealed that vegetation had increased along a latitudinal gradient between 63 degrees North and 69 degrees North and declined north of this.

Jonathan Carrivick said: "We have seen signs that the loss of ice is triggering other reactions which will result in further loss of ice and further 'greening' of Greenland, where shrinking ice exposes bare rock that is then colonised by tundra and eventually shrub.

"At the same time, water released from the melting ice is moving sediment and silt, and that eventually forms wetlands and fenlands."

Loss of ice triggers further warming

The loss of ice affects land surface temperatures because of albedo, which is the measure of how reflective a surface is.

Snow and ice are good reflectors of the sun's energy hitting the Earth's surface and this helps to keep the Earth cooler. As the ice retreats, it exposes bedrock which absorbs more solar energy, raising the temperature of the land surface.

Similarly, as ice melts it increases the quantity of water in lakes. Water absorbs more solar energy than snow and this also increases the temperature of the land surface.

Greenhouse gas emitter

The analysis shows a near quadrupling of wetlands across Greenland, particularly in the east and north-east. The wetlands are a source of methane emissions.

Writing in the paper, the researchers noted: "Expansion of vegetation and especially in wetland areas indicates but also exacerbates permafrost thaw, active layer thickening and thus emissions of greenhouse gasespreviously stored in these Arctic soils."

The researchers also developed a model to predict those areas on Greenland that are likely to see "marked and accelerated" change in the future.

Dr Michael Grimes, the lead author of the report who conducted the research as part of their PhD, added: "The expansion of vegetation, occurring in tandem with the retreat of glaciers and the ice sheet, is significantly altering the flow of sediments and nutrients into coastal waters.

"These changes are critical, particularly for the indigenous populations whose traditional subsistence hunting practices rely on the stability of these delicate ecosystems.

Read more at Science Daily

Polar bears unlikely to adapt to longer summers

More time stranded on land means greater risk of starvation for polar bears, a new study indicates.

During three summer weeks, 20 polar bears closely observed by scientists tried different strategies to maintain energy reserves, including resting, scavenging and foraging.

Yet nearly all of them lost weight rapidly: on average around 1 kilogram, or 2.2 pounds, per day.

Some have speculated that polar bears might adapt to the longer ice-free seasons due to climate warming by acting like their grizzly bear relatives and either rest or eat terrestrial food.

The polar bears in this study tried versions of both strategies -- with little success.

"Neither strategy will allow polar bears to exist on land beyond a certain amount of time. Even those bears that were foraging lost body weight at the same rate as those that laid down," said Charles Robbins, director of the Washington State University Bear Center and co-author of the study in the journal Nature Communications.

"Polar bears are not grizzly bears wearing white coats. They're very, very different."

Usually larger than grizzly bears, adult male polar bears can reach 10 feet in length and weigh 1,500 pounds compared to grizzly bears' 8 feet and 800 pounds.

To maintain that great mass, polar bears rely on the energy-rich fat of seals, which they best catch on the ice.

Little has been known about polar bear energy expenditure and behavior when confined to land, so researchers used collars with video cameras and GPS to track polar bears summering in the western Hudson Bay region of Manitoba, Canada.

They wanted to see what the specialized ice-hunters ate and did during the extended time on land when their preferred seal prey was out of reach.

The researchers also weighed the bears before and after the observation period and measured their energy expenditures.

"We found a real diversity of bear behaviors, and as a result, we saw a diverse range of energy expenditures," said lead author Anthony Pagano, research wildlife biologist with the U.S. Geological Survey Polar Bear Research Program and former WSU post-doctoral researcher.

Many of the adult male polar bears simply laid down to conserve energy, burning calories at rates similar to hibernation.

Others, actively searched for food, consuming bird and caribou carcasses as well as berries, kelp and grasses.

In all, the researchers found a five-fold range in energy expenditure from an adult male that rested 98% of the time to the most active who clocked 330 kilometers (205 miles). Some adult females spent as much as 40% of their time foraging.

Yet all that activity didn't pay off.

"The terrestrial foods did give them some energetic benefit, but ultimately, the bears had to spend more energy to access those resources," said Pagano.

Three polar bears went for long swims -- one swimming 175 kilometers (about 110 miles) across the bay.

Two found carcasses in the water, a beluga and a seal, but neither bear could feed on their finds while swimming nor bring them back to land.

Only one bear out of the 20 gained weight after stumbling across a dead marine mammal on land.

The study focused on the southern-most extent of polar bear range in the western Hudson Bay, where climate warming is likely impacting the bears at a faster rate than other Arctic regions.

The polar bear population in the area has already declined by an estimated 30% since 1987.

This study indicates that polar bears across the Arctic are at risk of starvation as the ice-free period continues to grow.

"As polar bears are forced on land earlier, it cuts into the period that they normally acquire the majority of the energy they need to survive," said Pagano.

"With increased land use, the expectation is that we'll likely see increases in starvation, particularly with adolescents and females with cubs."

Read more at Science Daily

Great apes playfully tease each other

Babies playfully tease others as young as eight months of age. Since language is not required for this behavior, similar kinds of playful teasing might be present in non-human animals. Now cognitive biologists and primatologists from the University of California Los Angeles (UCLA, US), the Max Planck Institute of Animal Behavior (MPI-AB, Germany), Indiana University (IU, US), and the University of California San Diego (UCSD, US) have documented playful teasing in four species of great apes. Like joking behavior in humans, ape teasing is provocative, persistent, and includes elements of surprise and play. Because all four great ape species used playful teasing, it is likely that the prerequisites for humor evolved in the human lineage at least 13 million years ago.

Joking is an important part of human interaction that draws on social intelligence, an ability to anticipate future actions, and an ability to recognize and appreciate the violation of others' expectations.

Teasing has much in common with joking, and playful teasing may be seen as a cognitive precursor to joking.

The first forms of playful teasing in humans emerge even before babies say their first words, as early as eight months of age.

The earliest forms of teasing are repetitive provocations often involving surprise.

Infants tease their parents by playfully offering and withdrawing objects, violating social rules (so-called provocative non-compliance), and disrupting others' activities.

In a study recently published in the Proceedings of the Royal Society B, scientists from the University of California Los Angeles, the Max Planck Institute of Animal Behavior, Indiana University, and the University of California San Diego(Isabelle Laumer, Sasha Winkler, Federico Rossano, and Erica Cartmill) report evidence of playful teasing in the four great ape species: orangutans, chimpanzees, bonobos and gorillas.

"Great apes are excellent candidates for playful teasing, as they are closely related to us, engage in social play, show laughter and display relatively sophisticated understandings of others' expectations," says Isabelle Laumer (UCLA/MPI-AB) a post-doctoral researcher and the first author of the study.

The team analyzed spontaneous social interactions that appeared to be playful, mildly harassing, or provocative.

During these interactions, the researchers observed the teaser's actions, bodily movements, facial expressions, and how the targets of the teasing responded in turn.

They also assessed the teaser's intentionality by looking for evidence that the behavior was directed at a specific target, that it persisted or intensified, and that teasers waited for a response from the target.

The researchers found that orangutans, chimpanzees, bonobos and gorillas all engaged in intentionally provocative behavior, frequently accompanied by characteristics of play.

They identified 18 distinct teasing behaviors. Many of these behaviors appeared to be used to provoke a response, or at least to attract the target's attention.

"It was common for teasers to repeatedly wave or swing a body part or object in the middle of the target's field of vision, hit or poke them, stare closely at their face, disrupt their movements, pull on their hair or perform other behaviors that were extremely difficult for the target to ignore," explains UCLA and IU professor Erica Cartmill, senior author of the study.

Although playful teasing took many forms, the authors note that it differed from play in several ways.

"Playful teasing in great apes is one-sided, very much coming from the teaser often throughout the entire interaction and rarely reciprocated," explains Cartmill.

"The animals also rarely use play signals like the primate 'playface', which is similar to what we would call a smile, or 'hold' gestures that signal their intent to play."

Playful teasing mainly occurred when apes were relaxed, and shared similarities with behaviors in humans.

"Similar to teasing in children, ape playful teasing involves one-sided provocation, response waiting in which the teaser looks towards the target's face directly after a teasing action, repetition, and elements of surprise," Laumer explains.

Read more at Science Daily

Mysterious gap in size distribution of super-earths explained

Astronomers from Germany and Switzerland have uncovered evidence of how the enigmatic gap in the size distribution of exoplanets at around two Earth radii emerges. Their computer simulations demonstrate that the migration of icy, so-called sub-Neptunes into the inner regions of their planetary systems could account for this phenomenon. As they draw closer to the central star, evaporating water ice forms an atmosphere that makes the planets appear larger than in their frozen state. Simultaneously, smaller rocky planets gradually lose a portion of their original gaseous envelope, causing their measured radius to shrink over time.

Ordinarily, planets in evolved planetary systems, such as the Solar System, follow stable orbits around their central star. However, many indications suggest that some planets might depart from their birthplaces during their early evolution by migrating inward or outward. This planetary migration might also explain an observation that has puzzled researchers for several years: the relatively low number of exoplanets with sizes about twice as large as Earth, known as the radius valley or gap. Conversely, there are many exoplanets smaller and larger than this size.

"Six years ago, a reanalysis of data from the Kepler space telescope revealed a shortage of exoplanets with sizes around two Earth radii," Remo Burn explains, an exoplanet researcher at the Max Planck Institute for Astronomy (MPIA) in Heidelberg. He is the lead author of the article reporting the findings outlined in this article, now published in Nature Astronomy.

Where does the radius valley come from?

"In fact, we -- like other research groups -- predicted based on our calculations, even before this observation, that such a gap must exist," explains co-author Christoph Mordasini, a member of the National Centre of Competence in Research (NCCR) PlanetS. He heads the Division of Space Research and Planetary Sciences at the University of Bern. This prediction originated during his tenure as a scientist at MPIA, which has been jointly researching this field with the University of Bern for many years.

The most commonly suggested mechanism to explain the emergence of such a radius valley is that planets might lose a part of their original atmosphere due to the irradiation from the central star -- especially volatile gases like hydrogen and helium. "However, this explanation neglects the influence of planetary migration," Burn clarifies. It has been established for about 40 years that under certain conditions, planets can move inward and outward through planetary systems over time. How effective this migration is and to what extent it influences the development of planetary systems impacts its contribution to forming the radius valley.

Enigmatic sub-Neptunes

Two different types of exoplanets inhabit the size range surrounding the gap. On one hand, there are rocky planets, which can be more massive than Earth and are hence called super-Earths. On the other hand, astronomers are increasingly discovering so-called sub-Neptunes (also mini-Neptunes) in distant planetary systems, which are, on average, slightly larger than the super-Earths.

"However, we do not have this class of exoplanets in the Solar System," Burn points out. "That's why, even today, we're not exactly sure about their structure and composition."

Still, astronomers broadly agree that these planets possess significantly more extended atmospheres than rocky planets. Consequently, understanding how these sub-Neptunes' characteristics contribute to the radius gap has been uncertain. Could the gap even suggest that these two types of worlds form differently?

Wandering ice planets

"Based on simulations we already published in 2020, the latest results indicate and confirm that instead, the evolution of sub-Neptunes after their birth significantly contributes to the observed radius valley," concludes Julia Venturini from Geneva University. She is a member of the PlanetS collaboration mentioned above and led the 2020 study.

In the icy regions of their birthplaces, where planets receive little warming radiation from the star, the sub-Neptunes should indeed have sizes missing from the observed distribution. As these presumably icy planets migrate closer to the star, the ice thaws, eventually forming a thick water vapour atmosphere.

This process results in a shift in planet radii to larger values. After all, the observations employed to measure planetary radii cannot differentiate whether the determined size is due to the solid part of the planet alone or an additional dense atmosphere.

At the same time, as already suggested in the previous picture, rocky planets 'shrink' by losing their atmosphere. Overall, both mechanisms produce a lack of planets with sizes around two Earth radii.

Physical computer models simulating planetary systems

"The theoretical research of the Bern-Heidelberg group has already significantly advanced our understanding of the formation and composition of planetary systems in the past," explains MPIA Director Thomas Henning. "The current study is, therefore, the result of many years of joint preparatory work and constant improvements to the physical models."

The latest results stem from calculations of physical models that trace planet formation and subsequent evolution. They encompass processes in the gas and dust disks surrounding young stars that give rise to new planets. These models include the emergence of atmospheres, the mixing of different gases, and radial migration.

"Central to this study were the properties of water at pressures and temperatures occurring inside planets and their atmospheres," explains Burn. Understanding how water behaves over a wide range of pressures and temperatures is crucial for simulations. This knowledge has been of sufficient quality only in recent years. It is this component which permits realistic calculation of the sub-Neptunes' behaviour, hence explaining the manifestation of extensive atmospheres in warmer regions.

"It's remarkable how, as in this case, physical properties on molecular levels influence large-scale astronomical processes such as the formation of planetary atmospheres," Henning adds.

"If we were to expand our results to cooler regions, where water is liquid, this might suggest the existence of water worlds with deep oceans," Mordasini says. "Such planets could potentially host life and would be relatively straightforward targets for searching for biomarkers thanks to their size."

Further work ahead

However, the current work is just an important milestone. Although the simulated size distribution closely matches the observed one, and the radius gap is in the right place, the details still have some inconsistencies. For instance, too many ice planets end up too close to the central star in the calculations. Nonetheless, researchers do not perceive this circumstance as a disadvantage but hope to learn more about planetary migration in this way.

Read more at Science Daily

When the global climate has the hiccups

In recent geological history, the so-called Quaternary period, there have been repeated ice ages and warm periods. Researchers are able to determine past climate variability from the composition of climate records. In the case of the last glacial period 100,000 years ago, ice cores from Greenland in particular provide researchers with detailed data.

For example, Greenland ice cores show that there were repeated rapid increases in temperature.

"We are talking about increases of 5 to 10 degrees within 30 to 40 years on average in the case of Europe. A Neanderthal would have experienced increases in the average temperature of several degrees over the course of their life," explains Prof.

Dominik Fleitmann, Professor of Quaternary Geology at the University of Basel.

He calls the phenomena "climate hiccups."

These Dansgaard-Oeschger events are well documented fort the last glacial period, but the climate records from Greenland only cover the last 120,000 years.

It was therefore previously unknown whether these Dansgaard-Oeschger events also occurred during the penultimate glacial period 135,000 to 190,000 years ago.

Frederick Held, a PhD candidate in Fleitmann's research group, was able to show that Dansgaard-Oeschger events also occurred during the penultimate glacial period using isotopic measurements on stalagmites.

He is the lead author of the study which was published in the scientific journal Nature Communications.

The North Atlantic as the source of change

The stalagmites examined originate from the Sofular Cave in Turkey, which is located in a region that is very sensitive to climate change.

The researchers therefore refer to it as a key region, as it is influenced by the winds of the North Atlantic and the Black Sea is just a few kilometers away.

"We used the isotopic composition in the stalagmites to determine the moisture sources from which they are formed -- the Black Sea, the Mediterranean Sea and the North Atlantic," explains Frederick Held.

For the first time, the evaluations carried out on the stalagmites from the Sofular Cave have proven that Dansgaard-Oeschger events also occurred during the penultimate glacial period.

"It was previously unknown whether these relatively brief temperature events actually happened in earlier glacial periods," states Held.

However, they occurred less frequently in the penultimate glacial period than in the last one: "The temperature peaks are twice as far apart from one another, meaning there were longer cold phases between them."

These temperature fluctuations originate in the North Atlantic, as the circulation of the ocean is a global conveyor belt for heat and can sometimes be stronger and sometimes weaker.

"For example, the circulation affects the exchange of heat between the atmosphere and the ocean, which, in turn, impacts the balance of heat in the Northern Hemisphere and air flows and rainfall," explains Held.

He states that weakened circulation also reduces the quantity of CO2 which the ocean absorbs from the atmosphere.

These ocean currents were different in the penultimate glacial period than in the last one, which explains the different intervals between the Dansgaard-Oeschger events.

This shows that not all glacial periods are the same and not all warm periods are the same.

The researchers compared the data from the stalagmites with marine sediment cores, which also act as natural climate archive.

The more pieces there are in the puzzle, the more accurate the picture of what happened, and feedback mechanisms can be captured more precisely.

Better understanding the mechanisms

Taking a look at the last two glacial periods, it becomes clear how fast climate can change.

"Climate change drives forward new ecosystems," says Dominik Fleitmann.

"Our dream is to create a continuous dataset for the last 600,000 to 700,000 years and close any gaps in our knowledge."

The evaluations help us to better understand the Earth in terms of which factors result in abrupt fluctuations in climate, what trends can be observed and how and under what conditions the oceans' circulation patterns change.

Current climate models can be tested using data from the past.

"Patterns that are established can help climate researchers to further improve their models and therefore refine assumptions for future trends," explains Fleitmann.

Read more at Science Daily

Archaeologists discover oldest known bead in the Americas

University of Wyoming archaeology Professor Todd Surovell and his team of collaborators have discovered a tube-shaped bead made of bone that is about 12,940 years old.

The bead, found at the La Prele Mammoth site in Converse County, is the oldest known bead in the Americas.

Surovell's research was published in the peer-reviewed journal Scientific Reports; the paper is titled "Use of hare bone for the manufacture of a Clovis bead." Members of the research team included people from UW, the Office of the Wyoming State Archaeologist, the University of Manchester, Weber State University and Chico State University.

The La Prele Mammoth site preserves the remains of a killed or scavenged sub-adult Columbian mammoth and an associated camp occupied during the time the animal was butchered.

To determine the origin of the bone bead, the team extracted collagen for zooarchaeology by mass spectrometry, also known as ZooMS, which allowed the group to gain insights about the chemical composition of the bone.

The researchers concluded that the bead was made from either a metapodial (the bones that link the phalanges of the digits to the more proximal bones of the limb) or a proximal phalanx (a bone found in the fingers and toes of humans and other vertebrates) of a hare.

This finding represents the first secure evidence for the use of hares during the Clovis period, which refers to a prehistoric era in North America, particularly prominent about 12,000 years ago.

It's named after the Clovis archaeological site in New Mexico, where distinctive stone tools were discovered.

The bead is about 7 millimeters in length, and its internal diameter averages 1.6 millimeters.

The research team considered the possibility that the bead could have been the result of carnivore consumption and digestion and not created by humans; however, carnivores were not common on this site, and the artifact was recovered 1 meter from a dense scatter of other cultural materials.

Additionally, the grooves on the outside of the bead are consistent with creation by humans, either with stones or their teeth.

Beads like this one were likely used to decorate their bodies or clothing.

Read more at Science Daily

Artificial cartilage with the help of 3D printing

Is it possible to grow tissue in the laboratory, for example to replace injured cartilage? At TU Wien (Vienna), an important step has now been taken towards creating replacement tissue in the lab -- using a technique that differs significantly from other methods used around the world.

A special high-resolution 3D printing process is used to create tiny, porous spheres made of biocompatible and degradable plastic, which are then colonized with cells.

These spheroids can then be arranged in any geometry, and the cells of the different units combine seamlessly to form a uniform, living tissue.

Cartilage tissue, with which the concept has now been demonstrated at TU Wien, was previously considered particularly challenging in this respect.

Tiny spherical cages as a scaffold for the cells

"Cultivating cartilage cells from stem cells is not the biggest challenge. The main problem is that you usually have little control over the shape of the resulting tissue," says Oliver Kopinski-Grünwald from the Institute of Materials Science and Technology at TU Wien, one of the authors of the current study.

"This is also due to the fact that such stem cell clumps change their shape over time and often shrink."

To prevent this, the research team at TU Wien is working with a new approach: specially developed laser-based high-resolution 3D printing systems are used to create tiny cage-like structures that look like mini footballs and have a diameter of just a third of a millimeter.

They serve as a support structure and form compact building blocks that can then be assembled into any shape.

Stem cells are first introduced into these football-shaped mini-cages, which quickly fill the tiny volume completely.

"In this way, we can reliably produce tissue elements in which the cells are evenly distributed and the cell density is very high. This would not have been possible with previous approaches," explains Prof.

Aleksandr Ovsianikov, head of the 3D Printing and Biofabrication research group at TU Wien.

Growing together perfectly

The team used differentiated stem cells -- i.e. stem cells that can no longer develop into any type of tissue, but are already predetermined to form a specific type of tissue, in this case cartilage tissue.

Such cells are particularly interesting for medical applications, but the construction of larger tissue is challenging when it comes to cartilage cells.

In cartilage tissue, the cells form a very pronounced extracellular matrix, a mesh-like structure between the cells that often prevents different cell spheroids from growing together in the desired way.

If the 3D-printed porous spheres are colonized with cells in the desired way, the spheres can be arranged in any desired shape.

The crucial question is now: do the cells of different spheroids also combine to form a uniform, homogeneous tissue?

"This is exactly what we have now been able to show for the first time," says Kopinski-Grünwald.

"Under the microscope, you can see very clearly: neighboring spheroids grow together, the cells migrate from one spheroid to the other and vice versa, they connect seamlessly and result in a closed structure without any cavities -- in contrast to other methods that have been used so far, in which visible interfaces remain between neighboring cell clumps."

The tiny 3D-printed scaffolds give the overall structure mechanical stability while the tissue continues to mature.

Over a period of a few months, the plastic structures degrade, they simply disappear, leaving behind the finished tissue in the desired shape.

First step towards medical application

In principle, the new approach is not limited to cartilage tissue, it could also be used to tailor different kinds of larger tissues such as bone tissue.

However, there are still a few tasks to be solved along the way -- after all, unlike in cartilage tissue, blood vessels would also have to be incorporated for these tissues above a certain size.

Read more at Science Daily

Newly discovered carbon monoxide-runaway gap can help identify habitable exoplanets

A carbon monoxide (CO)-runaway gap identified in the atmospheres of Earth-like planets by researchers at Tokyo Tech can help expand the search for habitable planets. This gap, identified through atmospheric modeling, is an indicator of a CO-rich atmosphere on Earth-like planets orbiting Sun-like stars. CO is an important compound for the formation of prebiotic organic compounds, which are building blocks for more complex molecules for the formation of life.

The search for habitable exoplanets involves looking for planets with similar conditions to the Earth, such as liquid water, a suitable temperature range and atmospheric conditions.

One crucial factor is the planet's position in the habitable zone, the region around a star where liquid water could potentially exist on the planet's surface.

NASA's Kepler telescope, launched in 2009, revealed that 20-50% of visible stars may host such habitable Earth-sized rocky planets.

However, the presence of liquid water alone does not guarantee a planet's habitability.

On Earth, carbon compounds such as carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) played a crucial role in shaping the climate and biogeochemistry and could have contributed to the emergence of life.

Taking this into consideration, a recent study by Associate Professor Kazumi Ozaki from Tokyo Institute of Technology, along with Associate Researcher Yasuto Watanabe from The University of Tokyo, aims to expand the search for habitable planets.

Published in the Astrophysical Journal on 10 January 2024, the researchers used atmospheric modeling to identify conditions that could result in a CO-rich atmosphere on Earth-like planets that orbit sun-like (F-, G-, and K-type) stars.

This phenomenon, known as CO runaway, is suggested by atmospheric models to have possibly occurred in early planetary atmospheres, potentially favoring the emergence of life.

"The possibility of CO runaway is critical in resolving the fundamental problem regarding the origin of life on Earth because various organic compounds suitable for the prebiotic chemistry are more likely to form in a CO-rich atmosphere than in a CO2-rich atmosphere," explains Dr. Ozaki.

The researchers modeled the CO cycle between the atmosphere and the oceans, considering the various sources of CO production, its transport mechanisms and the processes involved in its removal.

The photolysis of CO2, in which CO2 breaks down into CO when exposed to light, was considered the primary source of CO. Additional sources included photochemical reactions in the atmosphere, emissions from volcanic gases, and the hydrothermal decomposition of formaldehyde (H2CO) in the ocean.

The removal of CO from the atmosphere primarily occurred through its reaction with hydroxyl (OH) radicals formed due to the photolysis of water vapor, and to a lesser extent, by deposition to the planet's surface.

The researchers found that a CO runaway occurs when the CO production surpasses the removal by OH radicals.

This can occur due to higher CO2 levels or the presence of reducing gases from volcanoes which compete for the OH radicals.

At a temperature of 277 K, conditions for CO runaway are met when the partial pressure of CO2 exceeds 0.2 bar.

However, at higher temperatures (300 K), a CO runaway needs even higher CO2 and volcanic gas levels due to increased water vapor in the atmosphere, which is a major source of OH radicals.

Once initiated, the CO levels in the atmosphere are limited only by surface deposition, where CO is deposited onto the planet's surface.

Notably, the changes in the CO, CO2 and CH4 levels before and after the runaway effect led to a gap reflected in the phase space defined by the ratios of their partial pressures (pCO/pCO2 and pCH4/pCO2). "Our results suggest that this CO-runaway gap is a general feature of Earth-like lifeless planets orbiting Sun-like stars, providing insights into the characteristics and potential habitability of exoplanets," says Dr. Ozaki.

Read more at Science Daily

Understanding how soil traps carbon

When carbon molecules from plants enter the soil, they hit a definitive fork in the road.

Either the carbon gets trapped in the soil for days or even years, where it is effectively sequestered from immediately entering the atmosphere. Or it feeds microbes, which then respire carbon dioxide (CO2) into the ever-warming environment.

In a new study, Northwestern University researchers determined the factors that could tip plant-based organic matter in one direction or the other.

By combining laboratory experiments and molecular modeling, researchers examined interactions between organic carbon biomolecules and a type of clay minerals known for trapping organic matter in soil. They found that electrostatic charges, structural features of carbon molecules, surrounding metal nutrients in soil and competition among molecules all play major roles in soil's ability (or inability) to trap carbon.

The new findings could help researchers predict which soil chemistries are most favorable for trapping carbon -- potentially leading to soil-based solutions for slowing human-caused climate change.

The research will be published on Feb. 9 in the Proceedings of the National Academy of Sciences.

"The amount of organic carbon stored in soil is about ten times the amount of carbon in the atmosphere," said Northwestern's Ludmilla Aristilde, the study's senior author. "If this enormous reservoir is perturbed, it would have substantial ripple effects. There are many efforts to keep carbon trapped to prevent it from entering the atmosphere. If we want to do that, then we first must understand the mechanisms at play."

An expert in the dynamics of organics in environmental processes, Aristilde is an associate professor of civil and environmental engineering at Northwestern's McCormick School of Engineering. Jiaxing Wang, a Ph.D. student in Aristilde's laboratory, is the paper's first author. Rebecca Wilson, an undergraduate student at Northwestern, is the paper's second author.

Common clay

Holding 2,500 billion tons of sequestered carbon, soil is one of Earth's largest carbon sinks -- second only to the ocean. But even though soil is all around us, researchers are only just beginning to understand how it locks in carbon to sequester it from the carbon cycle.

To investigate this process, Aristilde and her team looked to smectite clay, a type of clay mineral known to sequester carbon in natural soils. Then, they examined how the clay mineral's surface bonded to ten different biomolecules -- including amino acids, sugars related cellulose and phenolic acids related to lignin -- with varying chemistry and structures.

"We decided to study this clay mineral because it's everywhere," Aristilde said. "Nearly all soils have clay minerals. Also, clays are prevalent in semi-arid and temperate climates -- regions that we know will be affected by climate change."

Opposites attract

Aristilde and her team first looked at interactions between clay minerals and individual biomolecules. Because clay minerals are negatively charged, biomolecules with positively charged components (lysine, histidine and threonine) experienced the strongest binding. But, interestingly, this binding was not solely determined by electrostatic charges. Using 3D computational modeling, the researchers found that the structure of the biomolecules also played a role.

"There are instances where two molecules are both positively charged, yet one has a better interaction with the clay than the other," Aristilde said. "It's because the structural features of the binding are also important. A molecule has to be flexible enough to adopt a structural arrangement that can position itself in a way that aligns its positively charged components with the clay. The lysine, for example, has a long arm with a positive charge that it can use to anchor itself."

A little help from friends

Following this logic, one might assume that negatively charged biomolecules were unable to bind to the clay. But Aristilde and her team discovered that surrounding, natural metal nutrients could intervene. Positively charged metals, such as magnesium and calcium, formed a bridge between the negatively charged biomolecules and clay minerals to create a bond.

"Even with a biomolecule that wouldn't normally bind to the clay, we saw a significant increase in binding when magnesium was there," Aristilde said. "So, natural metal constituents in the soil can facilitate carbon trapping. Although this is a widely reported phenomenon, we shed light on the structures and mechanisms."

Mix and mingle

When studying interactions between individual biomolecules and clay minerals, the researchers found binding was predictable and straightforward. To attain information more closely aligned with real-world environments, Aristilde and her team mixed the different biomolecules together.

"We know different types of biomolecules in the environment exists together," Aristilde said. "So, we also performed experiments with a mixture of biomolecules."

Although the researchers initially thought the biomolecules would compete with one another to interact with the clay, they instead discovered unexpected behaviors. In a surprising twist, even positively charged biomolecules with flexible structures were inhibited from binding to the clay minerals. While they easily bonded to the clay when alone, the biomolecules' urges to bond with one another appears to supersede their attractions to the clay.

"This has not been shown before," Aristilde said. "The energy of attraction between two biomolecules was actually higher than the energy of attraction of a biomolecule to the clay. That led to a decrease in adsorption. It changes the way we think about how molecules compete on the surface. They aren't just competing for binding sites on the surface. They can actually attract each other."

Read more at Science Daily

Green doesn't always mean clean: Cleaning products urgently need better regulation, researchers warn

Many cleaning products labelled as "green" emit just as many harmful chemicals as regular products, new research has revealed.

Researchers say there needs to be better regulation and more guidance for consumers about how safe cleaning products really are.

Potentially harmful

The study, published by The Royal Society of Chemistry in the journal Environmental Science: Processes & Impact, found that fragranced cleaning products can be potentially harmful for the air quality in people's homes.

Cleaning products emit a wide range of volatile organic compounds (VOCs), including some which are hazardous or can undergo chemical transformations to generate harmful secondary pollutants.

In recent years, "green" cleaners have become increasingly popular, with an implicit assumption that these are better for our health and the environment.

But the University of York research found this was not the case.

Secondary pollutants

As part of the study, the VOC composition of 10 regular and 13 green cleaners was examined by researchers.

Green cleaners generally emitted more monoterpenes than regular cleaners, resulting in increases in harmful secondary pollutant concentrations following use, such as formaldehyde and peroxyacyl nitrates.

The study found that the fragrance ingredients of these products were the source of the volatile monoterpenes.

As levels of these types of pollutants increase in the home, susceptible people can develop breathing problems or irritation of the eyes, nose, throat, or skin.

Repeated exposure to high concentrations of formaldehyde can possibly lead to cancer in some cases.

Misleading consumers

Ellen Harding-Smith, Environmental Chemistry researcher from the Department of Environment & Geography, said: "Our research found there is no strong evidence to suggest that clean green products are better for indoor air quality compared to regular products.

"In fact, there was very little difference. Many consumers are being misled by the marketing of these products and could be damaging the air quality in their homes as a result -- potentially putting their health at risk. For so many products on the supermarket shelves, green doesn't mean clean."

Compositional differences

The research was funded by the EPSRC and the project is called IMPeCCABLE.

It is a collaboration between the University of York's Department of Environment and Geography, the Department of Chemistry, and the Wolfson Atmospheric Chemistry Laboratory.

Miss Harding-Smith, who is PhD Candidate, added: "The study highlights potential compositional differences in the formulations of regular and green cleaners, for which there is currently very little information on in the available literature.

Read more at Science Daily

Low voice pitch increases standing among strangers

If you're looking for a long-term relationship or to boost your social status, lower your pitch, according to researchers studying the effects of voice pitch on social perceptions. They found that lower voice pitch makes women and men sound more attractive to potential long-term partners, and lower voice pitch in males makes the individual sound more formidable and prestigious among other men.

The results of the cross-cultural study, published in the journal Psychological Science, have implications for understanding human evolution and how people today confer and evaluate social status.

"Vocal communication is one of the most important human characteristics, and pitch is the most perceptually noticeable aspect of voice," said David Puts, study co-author and professor of anthropology at Penn State. "Understanding how voice pitch influences social perceptions can help us understand social relationships more broadly, how we attain social status, how we evaluate others on social status and how we choose mates."

To study how voice pitch influences social perceptions, the researchers selected two male and two female voice recordings all repeating the same sentence. They edited the clips to produce the average pitch for the speaker's sex plus a higher-pitched and lower-pitched version of each voice, for a total of 12 clips, and divided the clips into male-male and female-female pairings. The researchers then asked more than 3,100 participants across 22 countries, representing five continents and New Zealand, to listen to the paired recordings and answer questions about which voice sounded more attractive, flirtatious, formidable and prestigious.

The researchers found that women and men preferred lower-pitched voices when asked which voice they would prefer for a long-term relationship such as marriage. They also found that a lower male voice pitch made the individual sound more formidable, especially among younger men, and more prestigious, particularly among older men. Perceptions of formidability and prestige had a larger impact in societies with more relational mobility -- where group members interact more often with strangers -- and more violence.

"We looked at homicide rate as a way of quantifying the degree of physical violence in a society, which was probably an important factor for our male ancestors' reproductive success," Puts said, explaining that human males often experienced threats of violence in competition over mates and those who were bigger -- or seemed bigger -- tended to have more success. "Human males have sex traits, such as upper body muscle mass, that look like they were shaped by male use of force or threat of force to win mating opportunities. A low voice pitch exaggerates size. It makes an organism, whether it's a person or non-human primate, seem big and intimidating."

The fact that study participants across cultures perceived a lower male voice pitch as conferring formidability and high social status suggests that these characteristics were likely conferred to our ancestors as well, Puts said. He likened the effect to that of Darth Vader's voice in the Star Wars franchise: no matter where the character goes in the galaxy, his low pitch is perceived as formidable because larger beings tend to produce lower frequencies.

"The findings suggest that deep voices evolved in males because our male ancestors frequently interacted with competitors who were strangers, and they show how we can use evolutionary thinking and research from nonhuman animals to predict and understand how our psychology and behaviors vary across social contexts, including cross-culturally," Puts said. "Male traits such as deep voices and beards are highly socially salient, but this new research shows that the salience of at least one of these traits varies in predictable ways across societies, and it suggests that others, such as beards, do too."

In addition, the researchers found that men perceived females with higher-pitched voices as more attractive for short-term relationships, and women perceived higher pitches as sounding more flirtatious and being more attractive to men. In societies with lower relational mobility, where group members are more likely to know one another, women may perceive these flirtatious voices as a threat to existing social networks, according to the researchers.

"Female secondary sex traits, like voice, look like they're much better designed for mate attraction rather than threatening each other physically," Puts said. "We found that we could use relational mobility to predict women's sensitivity to raised voice pitch in competitors. Sensitivity may have been higher in societies with lower relational mobility because flirtatious behavior is not just a threat to your romantic relationship but your friendships as well."

A common misconception is that early humans lived only in small-scale societies where everybody knew each other, Puts said. This was sometimes true, but the ethnographic and archeological records show that group sizes were often large. And although many people lived in small societies, he added, mounting evidence suggests that they periodically joined other groups to form large-scale societies numbering in the hundreds or thousands. They sometimes lived in these larger groups for months at a time and maintained these social networks even when they returned to living in smaller communities.

Read more at Science Daily

Physicists capture the first sounds of heat 'sloshing' in a superfluid

In most materials, heat prefers to scatter. If left alone, a hotspot will gradually fade as it warms its surroundings. But in rare states of matter, heat can behave as a wave, moving back and forth somewhat like a sound wave that bounces from one end of a room to the other. In fact, this wave-like heat is what physicists call "second sound."

Signs of second sound have been observed in only a handful of materials. Now MIT physicists have captured direct images of second sound for the first time.

The new images reveal how heat can move like a wave, and "slosh" back and forth, even as a material's physical matter may move in an entirely different way. The images capture the pure movement of heat, independent of a material's particles.

"It's as if you had a tank of water and made one half nearly boiling," Assistant Professor Richard Fletcher offers as analogy. "If you then watched, the water itself might look totally calm, but suddenly the other side is hot, and then the other side is hot, and the heat goes back and forth, while the water looks totally still."

Led by Martin Zwierlein, the Thomas A Frank Professor of Physics, the team visualized second sound in a superfluid -- a special state of matter that is created when a cloud of atoms is cooled to extremely low temperatures, at which point the atoms begin to flow like a completely friction-free fluid. In this superfluid state, theorists have predicted that heat should also flow like a wave, though scientists had not been able to directly observe the phenomenon until now.

The new results, reported in the journal Science, will help physicists get a more complete picture of how heat moves through superfluids and other related materials, including superconductors and neutron stars.

"There are strong connections between our puff of gas, which is a million times thinner than air, and the behavior of electrons in high-temperature superconductors, and even neutrons in ultradense neutron stars," Zwierlein says. "Now we can probe pristinely the temperature response of our system, which teaches us about things that are very difficult to understand or even reach."

Zwierlein and Fletcher's co-authors on the study are first author and former physics graduate student Zhenjie Yan and former physics graduate students Parth Patel and Biswaroop Mikherjee, along with Chris Vale at Swinburne University of Technology in Melbourne, Australia. The MIT researchers are part of the MIT-Harvard Center for Ultracold Atoms (CUA).

Super sound

When clouds of atoms are brought down to temperatures close to absolute zero, they can transition into rare states of matter. Zwierlein's group at MIT is exploring the exotic phenomena that emerge among ultracold atoms, and specifically fermions -- particles, such as electrons, that normally avoid each other.

Under certain conditions, however, fermions can be made to strongly interact and pair up. In this coupled state, fermions can flow in unconventional ways. For their latest experiments, the team employs fermionic lithium-6 atoms, which are trapped and cooled to nanokelvin temperatures.

In 1938, the physicist László Tisza proposed a two-fluid model for superfluidity -- that a superfluid is actually a mixture of some normal, viscous fluid and a friction-free superfluid. This mixture of two fluids should allow for two types of sound, ordinary density waves and peculiar temperature waves, which physicist Lev Landau later named "second sound."

Since a fluid transitions into a superfluid at a certain critical, ultracold temperature, the MIT team reasoned that the two types of fluid should also transport heat differently: In normal fluids, heat should dissipate as usual, whereas in a superfluid, it could move as a wave, similarly to sound.

"Second sound is the hallmark of superfluidity, but in ultracold gases so far you could only see it in this faint reflection of the density ripples that go along with it," Zwierlein says. "The character of the heat wave could not be proven before."

Tuning in

Zwierlein and his team sought to isolate and observe second sound, the wave-like movement of heat, independent of the physical motion of fermions in their superfluid. They did so by developing a new method of thermography -- a heat-mapping technique. In conventional materials one would use infrared sensors to image heat sources.

But at ultracold temperatures, gases do not give off infrared radiation. Instead, the team developed a method to use radio frequencyto "see" how heat moves through the superfluid. They found that the lithium-6 fermions resonate at different radio frequencies depending on their temperature: When the cloud is at warmer temperatures, and carries more normal liquid, it resonates at a higher frequency. Regions in the cloud that are colder resonate at a lower frequency.

The researchers applied the higher resonant radio frequency, which prompted any normal, "hot" fermions in the liquid to ring in response. The researchers then were able to zero in on the resonating fermions and track them over time to create "movies" that revealed heat's pure motion -- a sloshing back and forth, similar to waves of sound.

"For the first time, we can take pictures of this substance as we cool it through the critical temperature of superfluidity, and directly see how it transitions from being a normal fluid, where heat equilibrates boringly, to a superfluid where heat sloshes back and forth," Zwierlein says.

The experiments mark the first time that scientists have been able to directly image second sound, and the pure motion of heat in a superfluid quantum gas. The researchers plan to extend their work to more precisely map heat's behavior in other ultracold gases. Then, they say their findings can be scaled up to predict how heat flows in other strongly interacting materials, such as in high-temperature superconductors, and in neutron stars.

"Now we will be able to measure precisely the thermal conductivity in these systems, and hope to understand and design better systems," Zwierlein concludes.

Read more at Science Daily