Hexbyte Glen Cove Dead zones formed repeatedly in North Pacific during warm climates, study finds thumbnail

Hexbyte Glen Cove Dead zones formed repeatedly in North Pacific during warm climates, study finds

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Sediment cores from the Bering Sea hold a record of past low-oxygen events in the form of layered or “laminated” sediments. Credit: IODP

An analysis of sediment cores from the Bering Sea has revealed a recurring relationship between warmer climates and abrupt episodes of low-oxygen “dead zones” in the subarctic North Pacific Ocean over the past 1.2 million years.

The new study, led by researchers at UC Santa Cruz, was published June 2 in Science Advances. The findings provide crucial information for understanding the causes of low oxygen or “hypoxia” in the North Pacific and for predicting the occurrence of hypoxic conditions in the future.

“It is essential to understand whether is pushing the oceans toward a ‘tipping point’ for abrupt and severe hypoxia that would destroy ecosystems, food sources, and economies,” said first author Karla Knudson, who led the study as a graduate student in Earth sciences at UCSC.

The researchers based their findings on an analysis of deep sediment cores from a site in the Bering Sea. Over long periods of time, sediments are deposited and build up on the seafloor. The activity of organisms living in the seafloor sediments usually disrupts and mixes them as they accumulate, but if hypoxia has killed those organisms, an orderly pattern of layers is preserved. Thus, scientists can find a record of past hypoxic events in the form of these layered or “laminated” sediments in cores drilled from the seafloor.

Scientists have long known about a major episode of widespread hypoxia in the North Pacific at the end of the last ice age, when the melting of the ice sheets sent a massive influx of fresh water into the . The new study provides the first records of earlier low-oxygen events, and shows that the most recent occurrence was not representative of most of these events in terms of mechanisms or timing.

“It doesn’t take a huge perturbation like melting ice sheets for this to happen,” said corresponding author Ana Christina Ravelo, professor of ocean sciences at UC Santa Cruz. “These abrupt hypoxic events are actually common in the geologic record, and they are not typically associated with deglaciation. They almost always happen during the warm interglacial periods, like the one we’re in now.”

The hypoxia occurs after intense growth of phytoplankton (marine algae) in the surface waters. When the phytoplankton die, they sink deeper into the ocean and decompose, which depletes the oxygen and releases carbon dioxide into the water below the surface. What triggers these events, however, remains unclear. Ocean warming, high sea levels, and the availability of iron (a limiting factor for growth of phytoplankton) all seem to play a role.

Crew members abroad the research vessel JOIDES Resolution drilled sediment cores from the seafloor in the Bering Sea during a 2009 IODP expedition on which UCSC ocean scientist Christina Ravelo was co-chief scientist. Credit: Carlos Alvarez Zarikian, IODP/TAMU

“Our study shows that high sea levels, which occur during warm interglacial climates, contributed to these hypoxic events,” Knudson said. “During high sea levels, dissolved iron from the flooded can be transferred to the open ocean and promote intense phytoplankton growth in the surface waters.”

Although high sea level is an important background condition, it is not enough to trigger a hypoxic event by itself. Changes in ocean circulation, including intensified upwelling to bring more nutrients into the surface waters and stronger currents that could transfer iron from the continental shelf to the open ocean, may play a critical role, Knudson said.

Currently, regional dead zones occur in coastal areas around the world due to the temperature effects of climate warming, as well as nutrient enrichment of coastal waters from agricultural fertilizers. But even the massive dead zone at the mouth of the Mississippi River pales in comparison to the widespread hypoxia that occurred all across the North Pacific Ocean at the end of the last ice age.

Because the new study is based on sediment cores from a single site, the researchers do not know the extent of the it records—whether they were confined to the Bering Sea or extended across the North Pacific rim as the most recent event did.

“We don’t know how extensive they were, but we do know they were very intense and lasted longer than the deglaciation event that has been so well studied,” said Ravelo, who was co-chief scientist of Integrated Ocean Drilling Program Expedition 323, which recovered the Bering Sea cores in 2009.

Knudson said the cores record multiple events during each interglacial period throughout the Pleistocene, with abrupt transitions where laminated sediments appear and disappear in the core.

The new findings raise concerns about whether climate change and ocean warming will lead to a tipping point that would trigger widespread hypoxia in the North Pacific Ocean.

“The system is primed for this type of event happening,” Ravelo said. “We need to know how extensive they were, and we need to rethink how these events are triggered, because we now know that it doesn’t take a huge perturbation. This study sets the stage for a lot of follow-up work.”



More information:
“Causes and timing of recurring subarctic Pacific hypoxia” Science Advances (2021). DOI: 10.1126/sciadv.abg2906

Citation:
Dead zones formed repeatedly in North Pacific during warm climates, study finds (2021, June 2)
retrieved 2 June 2021
from https://phys.org/news/2021-06-dead-zones-repeatedly-north-pacific.html

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Hexbyte Glen Cove Why moms take risks to protect their infants thumbnail

Hexbyte Glen Cove Why moms take risks to protect their infants

Hexbyte Glen Cove

The elevated pup-retrieval test was used to assess the willingness of mice to care for infants in risky/dangerous situations. See the accompanying video for the results. Credit: RIKEN

It might seem like a given that mothers take extra risks to protect their children, but have you ever wondered why? A new study led by Kumi Kuroda at the RIKEN Center for Brain Science (CBS) in Japan shows that in mice, this and other nurturing behaviors are driven in part by neurons in a small part of the forebrain that contains a protein called the calcitonin receptor. The study was published in Cell Reports.

Many simple behaviors, such as eating and drinking, are driven by parts of the hypothalamus. The new study focused on identifying the part that drives a much more complicated behavior: caring for infants. Kuroda says, “We were able to narrow down the necessary for parental and non- in to a subset of in the central MPOA region that contain the receptor.”

The team’s previous research pointed to the central MPOA (cMPOA) region of the hypothalamus as the hub of nurturing behavior. This part of the brain contains more than seven kinds of neurons, and the goal of the new study was to find a marker for the ones which are the most important for nurturing. The researchers visualized 20 candidate genes in the cMPOA of nurturing mice together with a marker for active neurons. Double labeling was highest for the calcitonin receptor gene, making it the most likely marker for nurturing-related neurons.

Next, the researchers examined these neurons in detail. There were three major findings. First, the number of cMPOA neurons with the calcitonin receptor was higher in post-partum than in virgin females, males, or fathers. Second, incoming and outgoing connections to these neurons from other parts of the brain changed in females after they gave birth. Third, silencing these neurons completely disrupted nurturing behavior. Nurturing behaviors in mice include , hovering over pups in the nest, and picking pups up and bringing them back to the nest—termed pup retrieval. After the critical neurons were silenced, virgin females left pups scattered around the cage, even after mating and birthing their own pups. Other behaviors such as nursing and nest building were also affected, and the mothers acted overall as if they had little motivation for nurturing behavior. As a result, many pups could not survive without intervention.







A virgin female mouse and a mother mouse are tested on the elevated pup-retrieval maze. As in the example, only mother mice retrieved the pups in this situation (although virgin mice did so willingly in the home cage when it was not dangerous). When the calcitonin receptor was downregulated, mothers also hesitated to take the risk. Credit: RIKEN

After establishing that cMPOA neurons expressing the calcitonin receptor are necessary for nurturing, the researchers hypothesized that the receptor itself has a special function in generating the enhanced motivation for nurturing observed in mothers. To test this hypothesis, the team devised a new pup retrieval test. Instead of placing the pups around the edges of their home cage, they placed them on an elevated maze. Being out in the arms of the elevated maze is a little unpleasant and scary for mice. Virgin females that would retrieve pups in the cage refused to do it in the elevated maze. In contrast, mother mice always retrieved the pups, showing that their drive to nurture was greater. However, when calcitonin receptor levels were reduced by about half, even mother mice hesitated and took much longer to complete the retrievals.

“Parents, both human and animal, must choose to sacrifice one behavior for another in order to care for their children,” says Kuroda. “We found that upregulation of the calcitonin receptor is like a push in the brain that motivates mice to care for their pups, suppressing their self-interest and tendency to avoid risky and unpleasant situations.”

“The next step is to examine calcitonin receptor-expressing cMPOA neuron’s role in the nurturing behavior of non-human primates, which should be more similar to what happens in humans.”



More information:
Yoshihara et al. (2021) Calcitonin receptor signaling in the medial preoptic area enables risk-taking maternal care. Cell Reports DOI: 10.1016/j.celrep.2021.109204

Citation:
Why moms take risks to protect their infants (2021, June 1)
retrieved 1 June 2021
from https://phys.org/news/2021-06-moms-infants.html

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Hexbyte Glen Cove The secret to stickiness of mussels underwater thumbnail

Hexbyte Glen Cove The secret to stickiness of mussels underwater

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Credit: Pohang University of Science & Technology (POSTECH)

Mussels survive by sticking to rocks in the fierce waves or tides underwater. Materials mimicking this underwater adhesion are widely used for skin or bone adhesion, for modifying the surface of a scaffold, or even in drug or cell delivery systems. However, these materials have not entirely imitated the capabilities of mussels.

A joint research team from POSTECH and Kangwon National University (KNU)—led by Professor Hyung Joon Cha and Ph.D. candidate Mincheol Shin of the Department of Chemical Engineering at POSTECH with Professor Young Mee Jeong and Dr. Yeonju Park of the Department of Chemistry at KNU—has analyzed Dopa and , which are the amino acids that make up the surface secreted by mussels, and verified that their roles are related to their location. The team has taken a step closer to revealing the secret of underwater adhesion by uncovering that these can contribute to surface adhesion and cohesion differently depending on their specific location.

The characteristic of mussel adhesive proteins that have been mimicked so far is that they contain a large number of a unique amino acid called Dopa. Dopa is a modified amino acid with one more attached to tyrosine, and research on underwater adhesion started with the fact that Dopa makes up a large component of the adhesive protein.

However, the research team questioned the fact that this excellent underwater adhesion of mussels is enabled by only one molecule and focused on observing the number and location of lysine, which is an amino acid as frequently occurring as Dopa.

As a result, the research team uncovered that Dopa and lysine are attached to each other with about half the probability. On the other hand, it was revealed that unlike what has been known so far, when Dopa and lysine are attached together, they do not always produce positive synergy. The researchers confirmed that in the case of the cation-π interaction, negative synergy is rather produced.

When Dopa and lysine are together, a difference in the density of water molecules occurs at the and the concentration of water molecules around Dopa is lowered. This lowered concentration enables a difference in the hydrogen bonding strength between the and the hydroxyl group of Dopa, thereby lowering the structural stability of the cation-π complex. Using Raman spectroscopy, the research team confirmed that the CH2 group located in the lysine chain situated close to Dopa and catechol of the adjacent Dopa form an intramolecular interaction, thereby lowering its stability.

The findings of this study make it possible to confirm how adhesive protein of mussels was designed, and it shows promise to be applicable for research on adhesive proteins of other organisms in the future.

“With this new discovery on the synergy between Dopa and lysine, which are known to always play a positive role in underwater adhesion, it will change the framework of the way adhesive materials are designed,” remarked Professor Hyung Joon Cha who led the research.

This research, which was recently published in Chemistry of Materials, was conducted as a part of the study titled “Understanding the underwater adhesion mechanism of adhesive organisms: controlling the balance between surface and cohesion,” which is a Mid-career Researcher Program of the Ministry of Science and ICT and the National Research Foundation of Korea.



More information:
Mincheol Shin et al, Two Faces of Amine–Catechol Pair Synergy in Underwater Cation−π Interactions, Chemistry of Materials (2021). DOI: 10.1021/acs.chemmater.1c00079

Provided by
Pohang University of Science & Technology (POSTECH)

Citation:
The secret to stickiness of mussels underwater (2021, June 1)
retrieved 1 June 2021
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Hexbyte Glen Cove Mind the nanogap: Fast and sensitive oxygen gas sensors thumbnail

Hexbyte Glen Cove Mind the nanogap: Fast and sensitive oxygen gas sensors

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Credit: Tokyo Tech

Oxygen (O2) is an essential gas not only for us and most other lifeforms, but also for many industrial processes, biomedicine, and environmental monitoring applications. Given the importance of O2 and other gases, many researchers have focused on developing and improving gas-sensing technologies. At the frontier of this evolving field lie modern nanogap gas sensors—devices usually comprised of a sensing material and two conducting electrodes that are separated by a minuscule gap in the order of nanometers (nm), or thousand millionths of a meter. When molecules of specific gases get inside this gap, they electronically interact with the sensing layer and the electrodes, altering measurable electric properties such as the resistance between the electrodes. In turn, this allows one to indirectly measure the concentration of a given gas.

Although nanogap gas sensors bear many more attractive properties than the closely related microgap gas sensors, they have proven much more difficult to mass produce reliably for gap distances in the order of tens of nanometers. At the Laboratory for Materials and Structures of Tokyo Tech, a team of scientists led by Dr. Yutaka Majima is seeking ways to fabricate better nanogap sensors. In their latest study, which was published in Sensors & Actuators: B. Chemical, the team presents a new strategy to produce nanogap oxygen gas sensors using platinum/titanium (Pt/Ti) electrodes and a cerium oxide (CeO2) sensing layer.

Two sensor designs were tested by Prof. Majima and his team. In the bottom-contact design, the CeO2 sensing layer is first deposited onto a silicon substrate and the two Pt/Ti electrodes are laid on top of the CeO2 through (EBL). With EBL, one draws custom shapes on a resist film using a focused beam of electrons with extreme precision. This then allows for the selective etching or evaporation of Pt/Ti regions, thus giving shape to the nanogap electrodes. The other design (top-contact) was produced using EBL as well, but the CeO2 was applied on top of the Pt/Ti electrodes as a thin coating layer.

With this fabrication strategy, the team managed to reliably produce stable Pt nanogaps as small as 20 nm, which was unprecedented in the literature. Both sensor designs exhibited similar and highly promising performances, as Dr. Majima remarks: “For a gap separation of 35 nm, our nanogap O2 gas sensors exhibited a fast response time of 10 seconds at a relatively low operating temperature of 573 K (300 °C); this is approximately three orders of magnitude shorter than that of microgap sensors under the same measurement conditions.” Moreover, their procedure offers better scalability than those for previously developed nanogap gas sensors.

In addition to the sensor designs, this study provided important insights on the electron hopping mechanisms by which O2 molecules modulate the resistance between the Pt electrodes in the presence of CeO2 at the nanogap. Taken together, the results of this study are paving the way to better gas-sensing devices, as Dr. Majima concludes: “Our nanogap gas sensors could be promising candidates for the development of a general gas-sensing platform with a low operating temperature.” In due time, nanogap gas shall surely find their way into more fields of application, including wearable biomedical devices, industrial condition monitoring, and environmental sensing.



More information:
Trong Tue Phan et al, 20-nm-Nanogap oxygen gas sensor with solution-processed cerium oxide, Sensors and Actuators B: Chemical (2021). DOI: 10.1016/j.snb.2021.130098

Citation:
Mind the nanogap: Fast and sensitive oxygen gas sensors (2021, June 1)
retrieved 1 June 2021

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Hexbyte Glen Cove A deep dive into organic carbon distribution in hadal trenches thumbnail

Hexbyte Glen Cove A deep dive into organic carbon distribution in hadal trenches

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Credit: CC0 Public Domain

Hadal trenches are one of the ocean’s most extreme and least studied regions. Hadal zones, which begin at depths of around 6,000 meters, were once thought to be “biological deserts,” but over time they have been shown to be teeming with life. However, the distribution and source of organic carbon in hadal sediments are still not well understood.

In a new study, Xu et al. analyze organic carbon characteristics in from two deep-ocean regions: the Kermadec Trench, which reaches depths of 10,177 meters and is located north of New Zealand where the Pacific plate is subducting beneath the Indo-Australian plate; and the Atacama Trench, which reaches depths of about 8,000 meters and was created where the Nazca plate is subducting beneath the South American plate. The team collected a dozen sediment cores on research cruises carried out by New Zealand’s R/V Tangaroa in 2017 and Germany’s R/V Sonne in 2018. The cores were collected from both within the hadal zones of the trenches and along the nonhadal, abyssal plains of the region.

In each , the researchers analyzed trends for several geochemical parameters, including total organic carbon content, the ratio of total organic carbon to total nitrogen content, and the stable carbon isotopic composition of total organic carbon. They looked at lipid biomarkers to determine how much of the organic carbon in the trenches came from eroded land and how much came from marine sources. In addition, the authors looked at radiocarbon isotopes to determine how long the organic carbon had been in the trenches.

The team found that samples from the Kermadec Trench and the Atacama Trench were 18% and 24% richer, respectively, in terrigenous (or land-based) than nonhadal sites. The significant amounts of terrigenous carbon in both trenches suggest that hadal zones could be important carbon sinks for land-derived .



More information:
Yunping Xu et al, Distribution, Source, and Burial of Sedimentary Organic Carbon in Kermadec and Atacama Trenches, Journal of Geophysical Research: Biogeosciences (2021). DOI: 10.1029/2020JG006189

This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.

Citation:
A deep dive into organic carbon distribution in hadal trenches (2021, May 31)
retrieved 31 May 2021
from https://phys.org/news/2021-05-deep-carbon-hadal-trenches.html

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Hexbyte Glen Cove Turning tree bark and compost into aircraft wings and plastic bags thumbnail

Hexbyte Glen Cove Turning tree bark and compost into aircraft wings and plastic bags

Hexbyte Glen Cove

Biopolymers derived from trees and crops are already used to make car interiors. Credit: Monsterkoi / Pixabay

Trees, crops and even organic waste can be transformed into a bewildering array of plastics to use in products ranging from single-use bags to heavy-duty airplane wings.

These so-called biopolymers could play a vital role in weaning us off petroleum plastics—which will help cut greenhouse gas emissions, and ensure plastics come from a renewable resource.

And in some cases they could help to reduce pollution. One of the major sources of plastic pollution is packaging, which accounted for nearly 40% of the plastic used in the EU in 2019, according to Plastics Europe, a trade association.

Researchers have developed ways to make biodegradable food waste bags and food packaging from municipal food and garden waste.

“You are transforming organic waste to make a waste bag, which is biodegradable. So you are closing the cycle—you don’t use other materials to make the (plastic) bag,” said Thomas Dietrich, an engineer in biotechnology at Spain’s TECNALIA, a research and technological development center.

Dietrich is project manager of a project called VOLATILE, which has developed a technology that can be integrated into existing municipal anaerobic digestion and composting plants. It uses microorganisms to break down into volatile fatty acids, which are the building blocks of the PHB and PHBV plastics used to make plastic bags and food packaging.

The main by-product is a residue which can be used to make compost. Hydrogen gas is another by-product, and it can be used to make electricity.

Biodegradable

Using biowaste to produce could help solve a major challenge caused by the majority of biodegradable plastics currently being used.

“Normally the big (industries) selling (biodegradable plastics) on the market use food-grade agricultural materials,” said Dietrich.

Because of the volumes needed, it will not be possible to use agricultural produce to replace petroleum-based packaging without competing with food crops or biofuels for agricultural land, said Dietrich.

“So we have to try to keep organic carbon in the economy without falling back on agriculture,” he said.

Plastic bags and packaging made with VOLATILE’s technology would end up in household biowaste and in theory could be used once more to produce volatile fatty acids—although this has not yet been tested by the VOLATILE team.

One of the main challenges to this type of system is the lack of composting plants in most regions of the world, including Europe.

Across the EU, up to 50% of municipal solid waste is organic, and only about 40% of biowaste is recycled into high-quality compost and digestate, says the European Compost Network. The majority goes to landfill or for incineration.

However, this is likely to improve. The European Environment Agency says recycling more municipal bio-waste is ‘crucial’ for meeting EU targets to recycle and reuse at least 60% of all waste by weight by 2030.

Composition

Whether plastics are biodegradable or not is due to their chemical composition—not their origins. So petroleum-based plastics can be biodegradable, and plant-based ones can be non-biodegradable.

However, a shift to biopolymers would help reduce greenhouse gas emissions produced to make the plastics—even if the end product is not biodegradable.

Whether plastics are biodegradable or not is due to their chemical composition – not their origins. So petroleum-based plastics can be biodegradable, and plant-based ones can be non-biodegradable. Credit: Sven Brandsma / Unsplash

“We need to achieve this (shift) in 10, or maximum 15, years because the climate stakes are so high,” said Vincent Placet, a research engineer at the FEMTO-ST Institute in France.

“The quantity of CO2 emitted to produce wood and plants is very low,” said Placet, adding that they also absorb atmospheric CO2 during growth. He coordinates a project called SSUCHY, which is developing load-bearing bio-based composites for use in automotive and aerospace industries.

Biopolymers derived from trees and crops are already used to make car interiors.

Other biopolymers are being developed to be load-bearing. These include thermoset plastics which are designed to last up to 30 years under harsh conditions—in airplane wings and bodies for example.

Some of the most widely used thermoset plastics are epoxies, which are used in composite materials. Composite materials comprise up to 50% of the latest airplanes by weight.

“We have produced a fully bio-based epoxy. Now the main issue is scaling it up,” said Placet.

To scale up, an entire supply chain needs to be created, starting with finding suppliers of the plant materials, he says.

One option is to use waste from forestry—tree bark, branches and roots. “It’s available in very large quantities and not used in any other application. In northern Europe, the feedstock is very large and we know it can answer the needs for this type of epoxy polymer,” said Placet.

Another challenge is how to make the processing greener and more cost competitive than their petrochemical equivalents. Petrochemical epoxies are cheaper to produce and use less power and solvents. However, some of those efficiencies are because they are done on an industrial scale instead of in a laboratory, Placet says.

“It’s doable from a technical point of view,” but more investment is needed to scale up and build the necessary value chains, he added.

1%

Globally, bio-based plastics comprise about 1% of the 368 million tons of plastic produced annually, says European Bioplastics.

Sourcing the remaining 99% from plants ‘is not an option,” says Sander Defruyt, head of the New Plastics Economy, an initiative of the UK-based Ellen MacArthur Foundation to redesign the future of plastics.

“Where is all that biomaterial going to come from, in a way that is regenerative and not depleting our ecosystems? The demands on our ecosystems will just go through the roof, and we’re already crossing planetary boundaries today,” he added.

Even biodegradable plastics will have limited impact on reducing plastic pollution because most of the world’s regions do not have the necessary industrial composting facilities, Defruyt says.

Addressing —and solving our reliance on petroleum-based plastics—requires eliminating all unnecessary plastics, and reusing the plastics that are needed, to keep them out of the environment.

After that, ‘the very little virgin plastic that we still need … will need to be shifted from fossil-based sources to regeneratively sourced bio-based plastics to stop that systems-dependence on finite fossil resources,” said Defruyt.



More information:
Biowaste derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks cordis.europa.eu/project/id/720777

Citation:
Turning tree bark and compost into aircraft wings and plastic bags (2021, May 31)
retrieved 31 May 2021
from https://phys.org/news/2021-05-tree-bark-compost-aircraft-wings.html

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Hexbyte Glen Cove New take on machine learning helps us 'scale up' phase transitions thumbnail

Hexbyte Glen Cove New take on machine learning helps us ‘scale up’ phase transitions

Hexbyte Glen Cove

A correlation configuration (top left) is reduced using a newly developed block-cluster transformation (top right). Both the original and reduced configurations have an improved estimator technique applied to give configuration pairs of different size (bottom row). Using these training pairs, a CNN can learn to convert small patterns to large ones, achieving a successful inverse RG transformation. Credit: Tokyo Metropolitan University

Researchers from Tokyo Metropolitan University have enhanced “super-resolution” machine learning techniques to study phase transitions. They identified key features of how large arrays of interacting particles behave at different temperatures by simulating tiny arrays before using a convolutional neural network to generate a good estimate of what a larger array would look like using correlation configurations. The massive saving in computational cost may realize unique ways of understanding how materials behave.

We are surrounded by different states or phases of matter, i.e. gases, liquids, and solids. The study of , how one phase transforms into another, lies at the heart of our understanding of matter in the universe, and remains a hot topic for physicists. In particular, the idea of universality, in which wildly different materials behave in similar ways thanks to a few shared features, is a powerful one. That’s why physicists study model systems, often simple grids of particles on an array that interact via simple rules. These models distill the essence of the common physics shared by materials and, amazingly, still exhibit many of the properties of real materials, like phase transitions. Due to their elegant simplicity, these rules can be encoded into simulations that tell us what materials look like under different conditions.

However, like all simulations, the trouble starts when we want to look at lots of particles at the same time. The computation time required becomes particularly prohibitive near phase transitions, where dynamics slows down, and the correlation length, a measure of how the state of one atom relates to the state of another some distance away, grows larger and larger. This is a real dilemma if we want to apply these findings to the real world: real materials generally always contain many more orders of magnitude of atoms and molecules than simulated matter.

That’s why a team led by Professors Yutaka Okabe and Hiroyuki Mori of Tokyo Metropolitan University, in collaboration with researchers in Shibaura Institute of Technology and Bioinformatics Institute of Singapore, have been studying how to reliably extrapolate smaller simulations to larger ones using a concept known as an inverse renormalization group (RG). The renormalization group is a fundamental concept in the understanding of phase transitions and led Wilson to be awarded the 1982 Nobel Prize in Physics. Recently, the field met a powerful ally in convolutional neural networks (CNN), the same machine learning tool helping computer vision identify objects and decipher handwriting. The idea would be to give an algorithm the state of a small array of particles and get it to estimate what a larger array would look like. There is a strong analogy to the idea of super-resolution images, where blocky, pixelated images are used to generate smoother images at a higher resolution.

Trends found from simulations of larger systems are faithfully reproduced by the trained CNNs for both Ising (left) and three-state Potts (right) models. (inset) Correct temperature rescaling is achieved using data at some arbitrary system size. Credit: Tokyo Metropolitan University

The team has been looking at how this is applied to spin models of matter, where particles interact with other nearby particles via the direction of their spins. Previous attempts have particularly struggled to apply this to systems at temperatures above a phase transition, where configurations tend to look more random. Now, instead of using spin configurations i.e. simple snapshots of which direction the particle spins are pointing, they considered correlation configurations, where each particle is characterized by how similar its own spin is to that of other particles, specifically those which are very far away. It turns out correlation configurations contain more subtle queues about how particles are arranged, particularly at higher temperatures.

Like all machine learning techniques, the key is to be able to generate a reliable training set. The team developed a new algorithm called the block-cluster transformation for correlation configurations to reduce these down to smaller patterns. Applying an improved estimator technique to both the original and reduced patterns, they had pairs of configurations of different size based on the same information. All that’s left is to train the CNN to convert the small patterns to larger ones.

The group considered two systems, the 2D Ising model and the three-state Potts model, both key benchmarks for studies of condensed matter. For both, they found that their CNN could use a simulation of a very small array of points to reproduce how a measure of the correlation g(T) changed across a phase transition point in much larger systems. Comparing with direct simulations of larger systems, the same trends were reproduced for both systems, combined with a simple temperature rescaling based on data at an arbitrary system size.

A successful implementation of inverse RG transformations promises to give scientists a glimpse of previously inaccessible system sizes, and help physicists understand the larger scale features of materials. The team now hopes to apply their method to other models which can map more complex features such as a continuous range of spins, as well as the study of quantum systems.



More information:
Kenta Shiina et al, Inverse renormalization group based on image super-resolution using deep convolutional networks, Scientific Reports (2021). DOI: 10.1038/s41598-021-88605-w

Provided by
Tokyo Metropolitan University

Citation:
New take on machine learning helps us ‘scale up’ phase transitions (2021, May 31)
retrieved 31 May 2021
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Hexbyte Glen Cove California already in throes of drought as summer looms thumbnail

Hexbyte Glen Cove California already in throes of drought as summer looms

Hexbyte Glen Cove

Water levels in the Lake Oroville reservoir, the second largest in California, are already far lower than in past years—a worrying sign of extreme drought.

Summer has not even begun and Lake Oroville, the second-largest reservoir in California that provides drinking water to more than 25 million people, is at less than half of its average capacity at this time of year.

It is a worrying indication of the worsening drought conditions in the northern part of the Golden State.

“When we go into a year like this with the reservoir low and with really dry conditions throughout the state, that is concerning,” John Yarbrough, the assistant deputy director of the California Department of Water Resources, told AFP.

“The reservoir is much lower than we would like to see it, much lower than typical at this time of year. It’s about 47 percent of average,” he said, pointing to the cracked earth forming the wall.

Since May 10, California Governor Gavin Newsom has declared a state of emergency linked to drought in more than 40 counties. Conditions in Butte County, where Lake Oroville is located, are already seen as “extreme,” the highest level.

And the situation—exacerbated by the effects of climate change across the western United States—is not expected to improve before the rains return in five or six months.

Yarbrough said that in 2019, which he called a “good year,” the water level reached the trees on the edge of the dam—meaning it was about 50 meters (165 feet) higher than usual.

Residents of the area told AFP they had never seen like this before.

Many of them recalled how in 2017, they had to evacuate because torrential rains had prompted authorities to fear that the dam would break under the pressure. Not even five years later, the situation has shifted dramatically.

Boat owners in Lake Oroville have been forced to remove their vessels from the water or risk seeing them run aground and suffer damage.

Evaporating snow

Lake Oroville, built in the 1960s at the confluence of three rivers, is the key component of California’s State Water Project, a massive network of reservoirs, aqueducts and pipelines bringing water from the northern part of the state to the south, which has a higher population and a far .

“This lake right here provides drinking water for 27 million Californians,” Yarbrough said, adding that it also irrigates “up to 750,000 acres” (303,000 hectares) of farmland.

On average, Northern California gets two-thirds of the state’s total precipitation, but this year has been particularly bad.

On April 1, which traditionally marks the end of snowfall in the state, snow reserves in the Sierra Nevada mountains—source for about a third of the water used in California—stood at only about 60 percent of the average.

“One unique thing this year is, as that snow melted, the runoff ended up soaking into dry soils and evaporating,” meaning very little runoff ended up in Lake Oroville, Yarbrough explained.

The waters contained by Oroville Dam, the tallest in the United States at 770 feet (235 meters), will not dry up that quickly, but at the end of the so-called dry season the lake is expected to be at its lowest level recorded since September 1977.

Fears of forest fires

After two years with very little precipitation, and with no assurances that upcoming seasons will be any better, restrictions are the next step.

The charred trees that dot the landscape around Lake Oroville are a stark reminder of the increased risk of wildfires as a result of the drought.

The California Department of Water Resources, which runs the State Water Project, has warned that it risks being unable to provide more than five percent of requested supplies this year.

The owners of dozens of boats moored on Lake Oroville were forced this week to put the vessels in dry dock, or risk seeing them run aground and be damaged.

Another serious consequence of the drought: the increased risk of wildfires, which is particularly worrying for authorities in a region that has been repeatedly devastated in recent years by massive forest blazes.

The charred trees that dot the landscape around Lake Oroville are a stark reminder: Last year, more than 6,500 square miles (17,000 square kilometers) went up in flames in California alone, and 33 people were killed, including 15 at Berry Creek, not far from Oroville.

This year, fires have already consumed five times more vegetation than at the same point in time in 2020.

“I think we’re in a long-term trend of drought conditions. And it’s been going on for about six years,” said Butte County fire chief John Messina.

“We’ve had a few wet years in between those years, but overall, we’re much drier than what we’re used to,” he said.

“It doesn’t take a rocket scientist to understand if you don’t have precipitation, your fuels don’t stay moist—and the drier the fuels are, the more potential there is to have a catastrophic wildfire, or at least an extremely busy summer in California.”



© 2021 AFP

Citation:
California already in throes of drought as summer looms (2021, May 30)
retrieved 30 May 2021
from https://phys.org/news/2021-05-california-throes-drought-summer-looms.html

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Hexbyte Glen Cove Nearly 400,000 flee DR Congo city over fears volcano could erupt again thumbnail

Hexbyte Glen Cove Nearly 400,000 flee DR Congo city over fears volcano could erupt again

Hexbyte Glen Cove

In the shadow of Nyiragongo: A child in the northern outskirts of Goma runs on a bed of solidified lava.

The eastern DR Congo city of Goma was eerily deserted after nearly 400,000 of its inhabitants fled following warnings that nearby Mount Nyiragongo volcano may erupt again.

The authorities geared up for a major humanitarian effort, centred on Sake, around 25 kilometres (15 miles) west of the city, where tens of thousands of people are gathered.

Located on the shore of Lake Kivu in the shadow of Africa’s most , the city has lived in fear since Nyiragongo roared back into life last weekend.

The strato-volcano spewed rivers of lava that claimed nearly three dozen lives and destroyed the homes of some 20,000 people before the eruption stopped.

Scientists have since recorded hundreds of aftershocks.

They warn of a potentially catastrophic scenario—a “limnic eruption” that could smother the area with suffocating carbon dioxide.

A report on an emergency meeting early Friday said 80,000 households—around 400,000 inhabitants—had emptied on Thursday following a “preventative” evacuation order.

Most people have headed for Sake or the Rwandan border in the northeast, while others have fled by boat across Lake Kivu.

Late Friday, Rwandan President Paul Kagame said those fleeing needed “urgent, global support”.

Most people have headed for Sake, around 25 kilometres (15 miles) west of Goma, and for the Rwandan border, in the northeast.

Aid efforts are being organised to provide drinking water, food and other supplies, and workers are helping to reunite children who became separated from their families.

Nearly 10,000 people are taking refuge in Bukavu on the southern bank of Lake Kivu, according to governor Theo Ngwabidje, many of them in host families.

Quieter night

Several days of aftershocks, some of them equivalent to small earthquakes, yielded to a quieter night Thursday, and tremors eased both in numbers and intensity, an AFP journalist said.

But late Friday afternoon black smoke could be seen rising from the crater on the horizon, causing worry.

General Constant Ndima, the military governor of North Kivu province, ordered the evacuation of districts that potentially applies to nearly 400,000 out of Goma’s 600,000 residents, according to an estimate by the UN humanitarian agency OCHA.

The wider Goma area has a population of around two million.

The authorities arranged transport towards Sake, but the roads became choked with cars, trucks, buses and people seeking safety on foot.

Satellite photo of the zone around the Nyiragongo volcano, showing lava flows towards the city of Goma.

Many spent the night in the open or slept in schools or churches.

Evacuee Eugene Kubugoo said the water was giving children diarrhoea, adding: “We don’t have anything to eat or any place to sleep.”

Tens of thousands had fled Goma last Saturday night but many returned when the eruption ended the following day.

‘Limnic’ risk

Friday’s report, issued after experts carried out a risk assessment at the volcano’s summit, said “seismicity and ground deformation continues to indicate the presence of magma under the Goma area, with an extension under Lake Kivu.”

People should remain vigilant and listen to news bulletins, as the situation “may change quickly”, it warned.

Volcanologists say the worst-case scenario is of an eruption under the lake.

This could release hundreds of thousands of tonnes of carbon dioxide (CO2) that are currently dissolved in the water’s depths.

Volcanologists say the worst-case scenario is of an eruption under the lake.

The gas would rise to the surface of the lake, forming an invisible cloud that would linger at ground level and displace oxygen, asphyxiating life.

In 1986, one of these so-called limnic eruptions killed more than 1,700 people and thousands of cattle at Lake Nyos in western Cameroon.

Empty city

On Friday, almost all of the shops and banks in central Goma were closed, and just a handful of people and some motorcycle taxis were on the usually bustling streets.

In the poorer districts in the north of the city, a handful of stores were open and there were more people, including children who gambolled near a water truck.

“I will stay in the city. I know that I’m in imminent danger but I don’t have a choice,” said Aline Uramahoro, who has a beer store.

“I will leave when the volcano starts spitting.”

Nearly 3,500 metres (11,500 feet) high, Nyiragongo straddles the East African Rift tectonic divide.

Hungry: Displaced people queue for food in Sake, 25 kms from Goma.

Its last major eruption, in 2002, claimed around 100 lives and the deadliest eruption on record killed more than 600 people in 1977.

Herman Paluku, who gave his age as 94, said he had seen them all—and insisted he wouldn’t budge this time.

“There is a small hill near here which means that the lava does not reach us. And that’s what protects us a bit,” he said in Swahili, his hands sweeping the air.

“I can never leave here, in this situation. I can’t.”



© 2021 AFP

Citation:
Nearly 400,000 flee DR Congo city over fears volcano could erupt again (2021, May 29)
retrieved 30 May 2021
from https://phys.org/news/2021-05-dr-congo-city-volcano-erupt.html

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part may be reproduced without the written permission. The content is provided for information purposes only.

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Hexbyte Glen Cove Retro milk float brings Londoners zero-plastic groceries thumbnail

Hexbyte Glen Cove Retro milk float brings Londoners zero-plastic groceries

Hexbyte Glen Cove

Ella Shone serves a customer from her electric milk float converted into a zero waste shop which brings “packaging-free” shopping to people’s doors.

Ella Shone’s small electric truck used to deliver milk but now she drives it around London, selling groceries and household goods that are free of plastic packaging.

The 32-year-old bought her “top-up truck” last year after the first coronavirus lockdown got her thinking about innovative ways to reduce waste.

She has found plenty of demand for her service, with customers scooping up dry groceries such as lentils or filling bottles from large dispensers of vinegar or washing detergent.

On a rainy day in May, the 32-year-old plied a route to eight stops in the up-and-coming district of Hackney in northeast London.

“It’s very straightforward: it’s a bit like a go-cart ride,” she said of driving the truck, which has a top speed of 30 miles (48 kilometres) per hour.

But she admitted the steering can get “a bit bumpy”.

At one stop, three customers bought dried mango, pasta, raisins and shampoo.

The mobile shop was created to bring “packaging-free” shopping to people’s doors, tapping into a growing demand for deliveries during the stay-at-home restrictions.

“I felt that there was a need to make it easier, to make it more accessible, more visible,” she said.

Nevertheless, she wasn’t immediately sure her idea was viable.

The electric vehicles were once commonly used by milkmen and women to deliver pint bottles of fresh milk on household doorsteps.

“When I started this, I thought I’d gone a bit mad on furlough leave”, she admitted.

During lockdown, Shone was on government-subsidised leave from her job in sales at a company producing sustainable condiments.

She decided to buy the truck with the money she saved during lockdown, wanting to offer a “community shopping experience”.

The truck deliveries launched in August last year and customers can book a stop online.

The electric vehicles—known commonly as milk floats—were once commonly used by milkmen and women to deliver pint bottles of fresh milk on household doorsteps.

Customers returned them for reuse and Shone says her truck prompts a “nostalgic” reaction.

But she is responding to very current concerns over , which disintegrates over time, creating ubiquitous microplastic pollution.

Activism targeting governments and corporations can help, she said, but added: “I think there’s a lot that needs to be done at consumer level.”

Ella Shone says her truck prompts a “nostalgic” reaction.

Pandemic ‘awakening’

The UK is the world’s second biggest producer of waste per person behind the United States, according to Greenpeace.

A study published in January by Greenpeace and the Environmental Investigation Agency found that the 10 largest supermarket chains in the UK reduced their use of plastic by just 1.6 percent in 2019, despite promises of change.

Shone is nevertheless optimistic about people’s motivation to cut down on wasteful packaging.

“During the pandemic, there has been a bit of a step back towards single-use (plastic) just because people are fearful of reusing something that might entail passing on COVID-19,” she said.

“But against that tide, I think there has been a bit of an awakening in terms of our responsibility towards the environment.”

In April, she raised £15,000 ($21,000) through a crowd-funding campaign, which allowed her to add more shelves to her float. She has also left her previous job.

Ultimately, Shone would like to see a ban on plastic packaging.

“There are so many areas where plastic is completely unnecessary and the government is not putting regulations on what corporations are allowed to do,” she said.

“And the recycling infrastructure is quite terrible as well.”



© 2021 AFP

Citation:
Retro milk float brings Londoners zero-plastic groceries (2021, May 29)
retrieved 30 May 2021
from https://phys.org/news/2021-05-retro-londoners-zero-plastic-groceries.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

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