Solving a murder case with physics

In 2009, famed music producer Phil Spector was found guilty of the murder of actress Lana Clarkson, who was found dead from a single gunshot to her mouth at close range in Spector's California mansion.

During the trial, the attorney argued that Spector couldn't have been the shooter because his white dinner jacket only had a handful blood droplets on it. If he shot Clarkson, the jacket would be covered with blood.

After watching a film about the trial, UIC Distinguished Professor Alexander Yarin was intrigued by the scientific questions it raised. Yarin and his colleagues from Iowa State University—Assistant Professor James Michael and Associate Professor Daniel Attinger— started researching blood spatter, and their recent papers show how Spector could be the shooter and remain relatively free of blood droplets.

The researchers discovered that the gases released from a gun's muzzle brakes escape in a series of turbulent vortex rings, which causes a phenomenon called "blood back spatter"—the blood that travels back toward the shooter—to reverse direction away from the shooter.

At shortrange shooting, the muzzle gasses interfere with the blood back spatter and deflect droplets. Researchers did simulations  and found that there are scenarios where droplets can be turned around completely and land behind the victim. Experiments confirmed that prediction.

In addition, the researchers noted that a shooter could stand in a certain position or at a specific angle and all backward blood spatter would be turned around, keeping the shooter clean.

Gen Li et al, Blood backspatter interaction with propellant gases, Physics of Fluids (2021). DOI: 10.1063/5.0045214

https://phys.org/news/2021-06-case-physics.html?utm_source=nwletter...

Lowering Blood Pressure in 5 Minutes

Physicists observationally confirm Hawking's black hole theorem for the first time

There are certain rules that even the most extreme objects in the universe must obey. A central law for black holes predicts that the area of their event horizons—the boundary beyond which nothing can ever escape—should never shrink. This law is Hawking's area theorem, named after physicist Stephen Hawking, who derived the theorem in 1971.

Fifty years later, physicists at MIT and elsewhere have now confirmed Hawking's area theorem for the first time, using observations of gravitational waves. Their results appear yesterday (2nd July,2021) in Physical Review Letters.

In the study, the researchers take a closer look at GW150914, the first gravitational wave signal detected by the Laser Interferometer Gravitational-wave Observatory (LIGO), in 2015. The signal was a product of two inspiraling black holes that generated a new black hole, along with a huge amount of energy that rippled across space-time as gravitational waves.

If Hawking's area theorem holds, then the horizon area of the new black hole should not be smaller than the total horizon area of its parent black holes. In the new study, the physicists reanalyzed the signal from GW150914 before and after the cosmic collision and found that indeed, the total event horizon area did not decrease after the merger—a result that they report with 95 percent confidence.

Their findings mark the first direct observational confirmation of Hawking's area theorem, which has been proven mathematically but never observed in nature until now. The team plans to test future gravitational-wave signals to see if they might further confirm Hawking's theorem or be a sign of new, law-bending physics.

Testing the black-hole area law with GW150914, Physical Review Letters (2021). journals.aps.org/prl/accepted/ … 4336d883136eb53c122b

https://phys.org/news/2021-07-physicists-observationally-hawking-bl...

Scientists discover a new class of memory cells in the brain

Scientists have long searched in vain for a class of brain cells that could explain the visceral flash of recognition that we feel when we see a very familiar face, like that of our grandmothers. But the proposed "grandmother neuron"—a single cell at the crossroads of sensory perception and memory, capable of prioritizing an important face over the rabble—remained elusive.

Now, new research reveals a class of neurons in the brain's temporal pole region that links face perception to long-term memory. It's not quite the apocryphal grandmother neuron—rather than a single cell, it's a population of cells that collectively remembers grandma's face. The findings, published in Science, are the first to explain how our brains inculcate the faces of those we hold dear.

"A fast link between face perception and memory in the temporal pole" Science (2021). science.sciencemag.org/lookup/ … 1126/science.abi6671

https://medicalxpress.com/news/2021-07-scientists-class-memory-cell...

Russia races Tom Cruise and Musk for first movie in space

Six decades after Soviet cosmonaut Yuri Gagarin became the first human to orbit Earth, earning Moscow a key win in the Cold War, Russia is again in a space race with Washington.

This time though the stakes are somewhat glitzier.

On October 5, one of Russia's most celebrated actresses, 36-year-old Yulia Peresild is blasting off to the International Space Station (ISS) with film director Klim Shipenko, 38.

Their mission? Shoot the first film in orbit before the Americans do.

If their plan falls into place, the Russians are expected to beat Mission Impossible star Tom Cruise and Hollywood director Doug Liman, who were first to announce their project together with NASA and Space X, the company of billionaire Elon Musk.

Its plot, which has been kept under wraps by the crew and Russia's space agency, has been revealed by Russian media outlets to feature a doctor dispatched urgently to the ISS to save a cosmonaut.

In preparation for this 21st-century space race, Peresild has since late May been undergoing intensive training at the Yuri Gagarin Cosmonaut Training Centre in Star City outside Moscow.

https://phys.org/news/2021-07-russia-tom-cruise-musk-movie.html?utm...

Scientists identify long-sought marker for COVID vaccine success

Groundbreaking methane synthesis discovery

An interdisciplinary team of scientists recently published research casting new light on a previously unknown element of the carbon cycle, thanks to data collected from Yellowstone National Park over more than a decade.

The study is the subject of a new paper published this week in the journal Proceedings of the National Academy of Science titled "Aerobic Bacterial Methane Synthesis."

They began studying the microbiology of Yellowstone Lake in 2007. While collecting data to analyze the lake's chemistry and the interaction of various microbes in the lake with the park's underlying thermal features, they noticed something seemed off. They came across some lake water gas chemistries that didn't make  sense.

That discrepancy illustrated what has been termed the "methane paradox." For years, scientists have understood that when microorganisms produce methane, they do it anaerobically, meaning they don't use oxygen. But in the surface waters of the lake where the team was seeing methane, none of those organisms were found.

Methane is a naturally occurring gas made up of carbon and hydrogen atoms. It is the byproduct of a number of biological processes, though human activities like mining coal and refining natural gas also produce methane. It is a greenhouse gas known to be much more potent when trapping heat in the atmosphere than carbon dioxide, which is why many researchers are interested in identifying where in the biosphere it is created and where it goes.

When they did the DNA extraction from the lake water, they couldn't find the anaerobic organisms that are usually responsible for the presence of methane. Instead, they discovered aerobic bacteria were involved, isolating a bacterium called Acidovorax, which then allowed them to begin understanding this process.

Thye used analytical equipment to identify the presence of methylamine and glycine betaine in the lake water, biochemicals the team hypothesized to be key in the process of methane production. To test the theory, they narrowed down which gene the Acidovorax bacteria needed to convert methylamine or glycine betaine into methane.

They could break this down to a basic discovery about methylamine conversion to methane under aerobic conditions

Through a series of microbial experiments and extensive analysis of the wider biological community present in the lake samples, scientists identified a known gene that encodes aspartate aminotransferase, or AAT, that seemed to be catalyzing the methane synthesis.

This is a fundamentally different process from anaerobic methane synthesis

Qian Wang et al, Aerobic bacterial methane synthesis, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2019229118

https://phys.org/news/2021-07-team-publishes-groundbreaking-methane...

Microbes in cow stomachs can break down plastic

Plastic is notoriously hard to break down, but researchers  have found that bacteria from a cow's rumen—one of the four compartments of its stomach—can digest certain types of the ubiquitous material, representing a sustainable way to reduce plastic litter.

The scientists suspected such bacteria might be useful since cow diets already contain natural plant polyesters.

Thye  looked at three kinds of polyesters. One, polyethylene terephthalate, commonly known as PET, is a synthetic polymer commonly used in textiles and packaging. The other two consisted of a biodegradable plastic often used in compostable plastic bags (polybutylene adipate terephthalate, PBAT), and a biobased material (Polyethylene furanoate, PEF) made from renewable resources.

They obtained rumen liquid from a slaughterhouse in Austria to get the microorganisms they were testing. They then incubated that liquid with the three types of plastics they were testing (which were tested in both powder and film form) in order to understand how effectively the plastic would break down.

According to their results, which were recently published in Frontiers in Bioengineering and Biotechnology, all three plastics could be broken down by the microorganisms from cow stomachs, with the plastic powders breaking down quicker than plastic film. 

Frontiers in Bioengineering and Biotechnology, DOI: 10.3389/fbioe.2021.684459a , www.frontiersin.org/articles/1 … ioe.2021.684459/full

https://phys.org/news/2021-07-microbes-cow-stomachs-plastic.html?ut...

Proving The Impossible

Antimicrobial Resistance, HAIs and the Environment!

New species of ‘fairy lantern’ from Malaysian rainforests

The shape of nanoparticles in body fluids may reveal the type of ca...

A recent study by scientists from Japanese universities has shown that the shape of cell-derived nanoparticles, known as "extracellular vesicles" (EVs), in body fluids could be a biomarker for identifying types of cancer. In the study, the scientists successfully measured the shape distributions of EVs derived from liver, breast, and colorectal cancer cells, showing that the shape distributions differ from one another. The findings were recently published in the journal Analytical Chemistry.

Certain fish skin can be grafted onto burns and diabetic wounds. The material recruits the body's own cells and is converted eventually into living tissue.

Climate changed the size of our bodies 

An interdisciplinary team of researchers has gathered measurements of body and brain size for over 300 fossils from the genus Homo found across the globe. By combining this data with a reconstruction of the world's regional climates over the last million years, they have pinpointed the specific climate experienced by each fossil when it was a living human.

The study reveals that the average body size of humans has fluctuated significantly over the last million years, with larger bodies evolving in colder regions. Larger size is thought to act as a buffer against colder temperatures: less heat is lost from a body when its mass is large relative to its surface area.

Nature Communications (2021). DOI: 10.1038/s41467-021-24290-7

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Our species, Homo sapiens, emerged around 300,000 years ago in Africa. The genus Homo has existed for much longer, and includes the Neanderthals and other extinct, related species such as Homo habilis and Homo erectus.

https://phys.org/news/2021-07-climate-size-bodies-extent-brains.htm...

Stem cells can use same method as plants and insects to protect against viruses

Researchers at the Francis Crick Institute have found a vital mechanism, previously thought to have disappeared as mammals evolved, that helps protect mammalian stem cells from RNA viruses such as SARS-CoV-2 and Zika virus. The scientists suggest this could one day be exploited in the development of new antiviral treatments.

On infecting a host, a virus enters cells in order to replicate. For most cells in mammals the first line of protection are proteins, called interferons. Stem cells, however, lack the ability to trigger an interferon response and there has been uncertainty about how they protect themselves.

In their study, published in Science today the scientists analyzed genetic material from mouse stem cells and found it contains instructions to build a protein, named antiviral Dicer (aviD), which cuts up viral RNA and so prevents RNA viruses from replicating. This form of protection is called RNA interference, which is the method also used by cells in plants and invertebrates.

In laboratory experiments which exposed engineered human cells to SARS-CoV-2, the virus infected three times fewer stem cells when aviD was present in the cells compared to when the researchers removed this protein.

An isoform of Dicer protects mammalian stem cells against multiple RNA viruses" Science (2021). science.sciencemag.org/lookup/ … 1126/science.abg2264

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It's fascinating to learn how stem cells protect themselves against RNA viruses. The fact this protection is also what plants and invertebrates use suggests it might be something that goes far back in mammalian history, right up to when the evolutionary tree spilt. For some reason, while all mammalian cells possess the innate ability to trigger this process, it seems to only be relied upon by stem cells.

By learning more about this process, and uncovering the secrets of our immune system we are hoping to open up new possibilities for drug development as we strive to harness our body's natural ability to fight infection

The scientists also grew mini brain organoids from mouse embryonic stem cells and found that, when infected with Zika virus, the organoids with aviD grew more quickly and less viral material was produced than in organoids without this protein. Similarly, when organoids were infected with SARS-CoV-2, there were fewer infected stem cells in the organoids with aviD.

https://phys.org/news/2021-07-stem-cells-method-insects-viruses.htm...

More cell phone data use is negatively affecting Wi-Fi performance, study finds

If service becomes slow when you're trying to send a quick email on your smartphone, you might scroll through your network options and discover how many Wi-Fi networks there are. In fact, this plethora of options is itself the problem. These networks are in competition with one another, limiting the speed at which each can operate.

Hidden-nodes in coexisting LAA & Wi-Fi: a measurement study of real deployments. arxiv.org/abs/2103.15591

Biological fireworks show 300 million years in the making

Five years ago, researchers  discovered that human eggs, when fertilized by sperm, release billions of zinc ions, dubbed "zinc sparks."

They now found out that these same sparks fly from highly specialized metal-loaded compartments at the egg surface when frog eggs are fertilized. This means that the early chemistry of conception has evolutionary roots going back at least 300 million years, to the last common ancestor between frogs and people.

And the research has implications beyond this shared biology and deep-rooted history. It could also help shape future findings about how metals impact the earliest moments in human development. This work may help inform our understanding of the interplay of dietary zinc status and human fertility.

They also discovered that fertilized frog eggs eject another metal, manganese, in addition to zinc. It appears these ejected manganese ions collide with sperm surrounding the fertilized egg and prevent them from entering.

These breakthroughs support an emerging picture that transition metals are used by cells to regulate some of the earliest decisions in the life of an organism.

John F. Seeler et al, Metal ion fluxes controlling amphibian fertilization, Nature Chemistry (2021). DOI: 10.1038/s41557-021-00705-2

https://phys.org/news/2021-07-biological-fireworks-million-years.ht...

Scientists reveal how cauliflowers develop their unique shape

 Have you ever wondered how a cauliflower grows into its strange shape? - The mystery of how this peculiar shaped vegetable forms has now been solved by a team of mathematicians and plant scientists.

Now a new study revealed that cauliflowers, and Romanescos in particular, are in fact buds that are designed to become flowers but which never reach their goal. The findings have been published in Science.

The research combines mathematical modelling and plant biology to show that instead of reaching flowering stage cauliflowers develop into stems, which in turn continue trying to produce flowers. The cauliflower is born from this chain reaction, resulting in a succession of stems upon stems.

This study shows that the brief incursion of buds into a flowering state profoundly affects their functioning and allows them, unlike normal stems, to grow without leaves and to multiply almost infinitely. The atypical shape of the Romanesco is explained by the fact that its stems produce buds more and more rapidly (whereas the production rate is constant in other cauliflowers). This acceleration gives each floret a pyramidal appearance, making the fractal aspect of the structure clear. The study highlights how the selection of mutations in plants during the process of domestication has changed their shape, sometimes drastically, into the fruits and vegetables on our shelves.

https://www.nottingham.ac.uk/news/scientists-reveal-how-cauliflower...

Although most plants present a geometric organisation in spirals along main and secondary axes (called "phyllotaxis"), cauliflowers present an unusual phyllotaxis with a multitude of spirals, nested over a wide range of scales. How such a fractal self-similar organization emerges from developmental mechanisms has, until now, remained elusive.

Combining experimental analyses in Arabidopsis thaliana cauliflower-like mutant with mathematical modelling, researchers found that curd self-similarity arises because growing plant tissues fail to form flowers but keep the “memory” of their transient passage in a floral state. Understanding this genetic mutation could help plant scientists optimise growth of related plants.

https://researchnews.cc/news/7684/Scientists-reveal-how-cauliflower...

Scientists Have Created a New Bendy And Flexible Form of Ice

Water ice isn't exactly known for its flexibility. In fact, it's quite the opposite: rigid and brittle, easily fracturing and snapping. It's why avalanches and sea ice fragmentation occur.

It's also why new research is so fascinating. Scientists have just grown microfibers of water ice that can bend in a loop – breaking the previous maximum strain by a significant percentage and opening up new opportunities for the exploration of ice physics.

Ice doesn't always behave the way we expect, and its elasticity – or rather, lack thereof – is a perfect example. Theoretically, it should have a maximum elastic strain of around 15 percent. In the real world, the maximum elastic strain ever measured was less than 0.3 percent. The reason for this discrepancy is that ice crystals have structural imperfections that drive up their brittleness.

So a team of researchers led by nanoscientist Peizhen Xu of Zhejiang University in China sought to create ice with as few structural imperfections as possible.

The experiment consisted of a tungsten needle in an ultracold chamber, sitting at around minus 50 degrees Celsius, much colder than has been previously attempted. Water vapor was released into the chamber, and an electric field was applied. This attracted water molecules to the tip of the needle, where they crystallized, forming a microfiber with a maximum width of around 10 micrometers,  smaller than the width of a human hair.

The next step was to lower the temperature to between minus 70 and minus150 degrees Celsius. Under these low temperatures, the researchers tried bending the ice fibers.

At minus 150 degrees Celsius, they found that a microfiber 4.4 micrometers across was able to bend into a nearly circular shape, with a radius of 20 micrometers. This suggests a maximum elastic strain of 10.9 percent – much closer to the theoretical limit than previous attempts.

Even better, when the researchers released the ice, it sprang back into its previous shape.

https://science.sciencemag.org/content/373/6551/187

https://www.sciencealert.com/scientists-have-created-a-new-bendy-an...

Sulfhemoglobinemia

Heritable Epigenetics: The right combination of parents can turn a gene off indefinitely

Evidence suggests that what happens in one generation—diet, toxin exposure, trauma, fear—can have lasting effects on future generations. Scientists think these effects result from epigenetic changes that occur in response to the environment and turn genes on or off without altering the genome or DNA sequence.

But how these changes are passed down through generations has not been understood, in part, because scientists have not had a simple way to study the phenomenon. A new study by researchers at the University of Maryland provides a potential tool for unraveling the mystery of how experiences can cause inheritable changes to an animal's biology. By mating nematode worms, they produced permanent epigenetic changes that lasted for more than 300 generations. The research was published on July 9, 2021, in the journal Nature Communications.

With their new findings, the researchers now think  some genes could be more vulnerable to permanent epigenetic change while other genes recover within a few generations. Although studies in worms are not the same as in humans, the research provides a window into biological processes that are likely shared, at least in part, by all animals.

"Mating can initiate stable RNA silencing that overcomes epigenetic recovery," Nature Communications (2021). DOI: 10.1038/s41467-021-24053-4

--

The research team found while breeding nematode worms that some matings led to epigenetic changes in offspring that continued to be passed down through as many generations as the scientists continued to breed them. This discovery will enable scientists to explore how epigenetic changes are passed to future generations and what characteristics make genes susceptible to permanent epigenetic changes.

They found that there are these RNA-based signals controlling gene expression. Some of these signals silence the gene and some of them are protective signals that prevent silencing. These signals are duking it out as the offspring develop. When the gene comes from the mother, the protective signal always wins, but when the gene comes from the father, the silencing signal almost always wins.

When the silencing signal wins, the gene is silenced for good, or for at least 300 generations, which is how long these researchers followed their laboratory-bred worms. Previous examples of epigenetic changes were more complex or they did not last more than a couple of generations. The researchers don't yet know why the silencing signal only wins some of the time, but this new finding puts them in a much better position to explore the details of epigenetic inheritance than ever before.

While they've found a set of genes that can be silenced almost permanently, most other genes are not affected the same way.

https://phys.org/news/2021-07-combination-parents-gene-indefinitely...

Resistance to last-resort antibiotic may be passing between pet dogs and their owners

The dangerous mcr-1 gene, which provides resistance to the last-resort antibiotic colistin, has been found in four healthy humans and two pet dogs. In two cases, both dog and owner were harbouring the gene, according to new research being presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) held online this year.

Since first being reported in China in 2015, the mcr-1 gene has been found in various people and animals around the world. It confers resistance to colistin, an antibiotic of last resort used to treat infections from some bacteria resistant to all other antibiotics. The nightmare scenario that could emerge is mcr-1 combining with already drug-resistant bacteria to create a truly untreatable infection.

The study showed that eight dogs out of the 102 pets (7.8%) and four humans out of 126 (3.2%) harboured bacteria with the mcr-1 gene. Three of the dogs were healthy, four had SSTIs and one had a UTI. None of the cats were carrying the gene.

Further analysis showed that the bacteria isolated from all 12 samples that were mcr-1 positive were resistant to multiple antibiotics.

In two households with dogs with SSTIs, the mcr-1 gene was found in both dog and owner. Genetic analysis of the samples suggested that in one of these two cases, the gene had been transmitted between pet and owner.While transmission in both directions is possible, it is thought that in this case the gene passed from dog to human, say the researchers.

The owners did not have infections and so did not need treatment. The sick dogs were successfully treated.

The researchers say their results show that the mcr-1 gene can be transmitted between dogs and their owners. This raises concerns that pets can act as reservoirs of the gene and so aid the spread of resistance to precious last-line antibiotics.

The study was presented at the ongoing European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) taking place online between July 9 and 12.

Source: EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

https://medicalxpress.com/news/2021-07-resistance-last-resort-antib...

90-year-old woman infected with UK and South African COVID-19 variants at the same time

Researchers in Belgium report on the case of a 90-year-old woman who was simultaneously infected with two different variants of concern (VOCs) of COVID-19, in a Case Report being presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) held online this year.

On March 3 2021, the woman, whose medical history was unremarkable, was admitted to the OLV Hospital in the Belgian city of Aalst after a spate of falls. She tested positive for COVID-19 on the same day. She lived alone and received nursing care at home, and had not been vaccinated against COVID-19.

Initially, there were no signs of respiratory distress and the patient had good oxygen saturation. However, she developed rapidly worsening respiratory symptoms, and died five days later.

When the patient's respiratory sample was tested for VOCs with PCR, they discovered that she had been infected by two different strains of the virus—one which originated in the UK, known as B.1.1.7 (Alpha), and another that was first detected in South Africa (B.1.351; Beta).

The presence of both strains was confirmed by PCR on a second respiratory sample, by sequencing of the S-gene and by whole genome sequencing.

"This is one of the first documented cases of co-infection with two SARS-CoV-2 variants of concern.

Both these variants were circulating in Belgium at the time, so it is likely that the lady was co-infected with different viruses from two different people. 

In January 2021, scientists in Brazil reported that two people had been simultaneously infected with two different strains of the coronavirus—the Brazilian variant known as B.1.1.28 (E484K) and a novel variant VUI-NP13L, which had previously been discovered in Rio Grande do Sul. But the study has yet to be published in a scientific journal [1]. Previous research has reported people infected with different influenza strains [2].

Whether the co-infection of the two variants of concern played a role in the fast deterioration of the patient is difficult to say.

 [1] Pervasive transmission of E484K and emergence of VUI-NP13L with evidence of SARS-CoV-2 co-infection events by two different lineages in Rio Grande do Sul, Brazil | medRxiv www.medrxiv.org/content/10.110 … 021.01.21.21249764v1

[2] Natural co-infection of influenza A/H3N2 and A/H1N1pdm09 viruses resulting in a reassortant A/H3N2 virus - ScienceDirect www.sciencedirect.com/science/ … ii/S1386653215007404

ECCMID ABSTRACT 04978: Case report: a 90-year-old lady infected with two CoVID-19 VoCs: 20I/501Y.V1 and 20H/501Y.V2

https://medicalxpress.com/news/2021-07-year-old-woman-infected-uk-s...

Protein appears to prevent tumor cells from spreading via blood vessels

Researchers have identified a specialized protein that appears to help prevent tumor cells from entering the bloodstream and spreading to other parts of the body.

They have discovered that this protein, TRPM7, senses the pressure of fluid flowing in the circulation and stops the cells from spreading through the vascular system. they also found that metastatic tumour  cells have markedly reduced levels of this sensor protein, and that is why they efficiently enter into the circulation rather than turning away from fluid flow.

The findings, published in Science Advances, help shed light on a little-understood part of metastasis called intravasation, when cancer cells that have separated from a primary tumour enter the circulation in order to travel to other parts of the body and establish colonies.

The researchers further show that artificially increasing the expression of TRPM7 in tumor cells may help stop intravasation—and ultimately metastasis—in its tracks.

Christopher L. Yankaskas et al, The fluid shear stress sensor TRPM7 regulates tumor cell intravasation, Science Advances (2021). DOI: 10.1126/sciadv.abh3457

https://medicalxpress.com/news/2021-07-protein-tumor-cells-blood-ve...

Just 25 mega-cities produce 52% of the world's urban greenhouse gas emissions

In 2015, 170 countries worldwide adopted the Paris Agreement, with the goal limiting the average global temperature increase to 1.5°C. Following the agreement, many countries and cities proposed targets for greenhouse gas mitigation. However, the UNEP Emissions Gap Report 2020 shows that, without drastic and strict actions to mitigate the climate crisis, we are still heading for a temperature increase of more than 3°C by the end of the 21st century.

A new study published in the journal Frontiers in Sustainable Cities presents the first global balance sheet of greenhouse gasses (GHGs) emitted by major cities around the world. The aim was to research and monitor the effectiveness of historical GHG reduction policies implemented by 167 globally distributed cities that are at different developmental stages.

While only covering 2% of the Earth's surface, cities are big contributors to the climate crisis. But current urban GHG mitigation targets are not sufficient to achieve global climate change targets by the end of this century. 

The results showed that both developed and developing countries have cities with high total GHG emissions, but that megacities in Asia (such as Shanghai in China and Tokyo in Japan) were especially important emitters. The inventory of per capita emissions showed that cities in Europe, the US, and Australia had significantly higher emissions than most cities in developing countries. China, classified here as a developing country, also had several cities where per capita emissions matched those of developed countries. It is important to note that many developed countries outsource high carbon production chains to China, which increases export-related emissions for the latter.

Restoring touch in nerves damaged by injury

Tel Aviv University's new and groundbreaking technology inspires hope among people who have lost their sense of touch in the nerves of a limb following amputation or injury. The technology involves a tiny sensor that is implanted in the nerve of the injured limb, for example in the finger, and is connected directly to a healthy nerve. Each time the limb touches an object, the sensor is activated and conducts an electric current to the functioning nerve, which recreates the feeling of touch. The researchers emphasize that this is a tested and safe technology that is suited to the human body and could be implanted anywhere inside of it once clinical trials will be done.

The researchers developed a sensor that can be implanted on a damaged nerve under the tip of the finger; the sensor connects to another nerve that functions properly and restores some of the tactile sensation to the finger. This unique development does not require an external power source such as electricity or batteries. The researchers explain that the sensor actually works on frictional force: whenever the device senses friction, it charges itself.

The device consists of two tiny plates less than half a centimeter by half a centimeter in size. When these plates come into contact with each other, they release an electric charge that is transmitted to the undamaged nerve. When the injured finger touches something, the touch releases tension corresponding to the pressure applied to the device—weak tension for a weak touch and strong tension for a strong touch—just like in a normal sense of touch.

The researchers explain that the device can be implanted anywhere in the body where tactile sensation needs to be restored, and that it actually bypasses the damaged sensory organs. Moreover, the device is made from biocompatible material that is safe for use in the human body, it does not require maintenance, the implantation is simple, and the device itself is not externally visible.

Iftach Shlomy et al, Restoring Tactile Sensation Using a Triboelectric Nanogenerator, ACS Nano (2021). DOI: 10.1021/acsnano.0c10141

https://phys.org/news/2021-07-nerves-injury.html?utm_source=nwlette...

Carbon Capture

Researchers unlock behavior of rare cells that evade antibiotics by 'playing dead'

Researchers have developed a new microfluidic platform to track a very rare type of cell that can survive antibiotic treatments. The results have important implications for microbiologists learning about the cellular control of bacterial physiology and for scientists looking to combat the emerging threat of antibiotic resistance bacteria that can lead to untreatable infections.

"Persister cells" are a very small subpopulation of cells that survive antibiotic treatment by staying dormant and then resume growth after the antibiotic has been removed. These cells are transient and are therefore harder to study and have no genetic changes, meaning that they cannot be identified using sequencing.

Since these "persister cells" are both rare and transient, a platform is needed to image cells over time with sufficiently large throughput. Now researchers from the University of Cambridge, Harvard Medical School and Harvard University have developed a platform designed to track more than 100,000 individual bacterial cells over hundreds of generations as they experience rounds of feast-and-famine cycles. An array of hundreds of thousands of traps are used to keep individual cells immobilized and infused with the contents from a growing culture—E. coli (Escherichia coli), normally found in the intestine, and Bacillus subtilis, commonly found in soil. A high-resolution microscope rapidly scans over each cell and tracks their fate over time. The results are reported in the journal Nature Microbiology.

Somenath Bakshi et al, Tracking bacterial lineages in complex and dynamic environments with applications for growth control and persistence, Nature Microbiology (2021). DOI: 10.1038/s41564-021-00900-4

https://phys.org/news/2021-07-behavior-rare-cells-evade-antibiotics...

Sex-specific immune response in COVID-19 linked to cellular metabolism

 Researchers studying COVID-19 patients have found a metabolic pathway that is highly correlated with immune responses only in male patients, a group known to be more likely to suffer severe cases and die of the disease, representing a potential target for therapeutic intervention. In a study published in the journal Science Signaling, the authors report that male COVID-19 patients were more likely than female patients or healthy control subjects to have elevated levels of kynurenic acid, a product of amino acid metabolism. High levels of kynurenic acid have been linked to several diseases, such as schizophrenia and HIV-related diseases. Male patients with severe COVID-19 cases were also more likely to have a high ratio of kynurenic acid to kynurenine, a byproduct of the amino acid L-tryptophan which is used to create the nutrient niacin. We know that men are at higher risk than women of contracting severe cases of COVID-19 and that sex differences in the body's immune responses  present a compelling explanation for this phenomenon.

We also know that immune responses are regulated in part by metabolites, and so these new findings offer a key window into the mechanisms underlying how this disease affects female and male patients differently

https://researchnews.cc/news/7739/Sex-specific-immune-response-in-C...

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The World's Most Dangerous Blood Type

Electric signals between individual cardiac cells regulate heartbeat

The rhythm in a working heart is regulated by electrical impulses. Disturbances of this bioelectrical process can result in cardiac arrhythmias, or irregularities in heartbeat—a common ailment that can lead to illness and death.

In Biophysics Reviews, researchers from Harvard Medical School provide a state-of-the-art update on how electrical impulses in the heart travel from cell to cell.

A functioning heart contracts to pump blood to the body and the lungs. Within the heart, a pacemaker acts as an electrical clock, sending out a signal that tells the heart when to contract. The whole muscle moves together, because each individual cell inside of it contracts in a coordinated manner and within a short time interval.

In order to do so, the initial electrical impulse, sent by the pacemaker, rapidly spreads through cells across the heart.

If one cell is excited electrically and the other is not, the excited cell becomes positively charged inside, and the resting cell is still negatively charged inside. As a consequence, a voltage gradient builds up between the cells. If you have a voltage gradient and a pathway with a low electrical resistance, a local current will flow.

The connections between cells forming the low resistance pathway and facilitating the current flow are called gap junctions. Each consists of many channels, which are formed when specific proteins from one cell dock and fuse to the proteins from another cell. Kléber said the fusing proteins look like placing the tips of your fingers on one hand to the fingers on the other hand.

The scientists delve into the properties of gap junctions and their constituent proteins, the so-called connexins. Kléber said one reason gap junction channels are interesting is because they are a highly dynamic system in equilibrium. The creation, or synthesis, of the channels equals the destruction.

"The turnover is very short," he said. "On one hand, the system is very stable during your whole life. On the other hand, if you measure it, it is constantly cycling in periods of a few hours."

The proteins found in gap junctions are important for processes not directly related to cell-cell connections, like mitochondrial function which creates energy, and trafficking, which transports molecules from the site of synthesis to their site of action in the cell interior.

You have to refrain from the idea that if you define the role of a protein in the body, that it has only a single function.

"Coupling between cardiac cells - an important determinant of electrical impulse propagation and arrhythmogenesis" Biophysics Reviews, aip.scitation.org/doi/10.1063/5.0050192

https://medicalxpress.com/news/2021-07-electric-individual-cardiac-...

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Are silver nanoparticles a silver bullet against microbes?

Antimicrobials are used to kill or slow the growth of bacteria, viruses and other microorganisms. They can be in the form of antibiotics, used to treat bodily infections, or as an additive or coating on commercial products used to keep germs at bay. These life-saving tools are essential to preventing and treating infections in humans, animals and plants, but they also pose a global threat to public health when microorganisms develop resistance to them, a concept known as antimicrobial resistance.

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Tree rings show record of newly identified extreme solar activity e...

The sun constantly emits a stream of energetic particles, some of which reach Earth. The density and energy of this stream form the basis of space weather, which can interfere with the operation of satellites and other spacecraft. A key unresolved question in the field is the frequency with which the sun emits bursts of energetic particles strong enough to disable or destroy space-based electronics.

Tree rings show record of newly identified extreme solar activity event

The sun constantly emits a stream of energetic particles, some of which reach Earth. The density and energy of this stream form the basis of space weather, which can interfere with the operation of satellites and other spacecraft. A key unresolved question in the field is the frequency with which the sun emits bursts of energetic particles strong enough to disable or destroy space-based electronics.

One promising avenue for determining the rate of such events is the dendrochronological record. This approach relies on the process by which a solar energetic particle (SEP) strikes the atmosphere, causing a chain reaction that results in the production of an atom of carbon-14. This atom subsequently can be incorporated into the structure of a tree; thus, the concentration of carbon-14 atoms in a tree ring can indicate the impact rate of SEPs in a given year.

To date, three events of extreme SEP production are well described in literature, occurring approximately in the years 660 BCE, 774–775 CE, and 992–993 CE. Each event was roughly an order of magnitude stronger than any measured in the space exploration era. Miyake et al. describe such an event, which occurred between 5411 BCE and 5410 BCE. Because of this burst, atmospheric carbon-14 increased 0.6 percent year over year in the Northern Hemisphere and was sustained for several years before dropping to typical levels.

Using statistical methods, the researchers identified a pattern of small carbon-14 fluctuations consistent with the sun's 11-year solar cycle; the event recorded in the tree ring occurred during a time of solar maximum. Notably, other evidence suggests that the sun was also undergoing a decades-long period of increasing activity.

If an extreme SEP burst is indeed the cause of the additional carbon-14, then these observations could aid in forecasting future events. However, tree ring  measurements cannot rule out other extraterrestrial causes, such as a nearby supernova explosion. Confirmation will require isotopic measurements of beryllium and chlorine taken from ice cores, according to the authors.

F. Miyake et al, A Single‐Year Cosmic Ray Event at 5410 BCE Registered in 14 C of Tree Rings, Geophysical Research Letters (2021). DOI: 10.1029/2021GL093419

https://phys.org/news/2021-07-tree-newly-extreme-solar-event.html?u...

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Gene editing 'blocks virus transmission' in human cells

Scientists have used CRISPR gene-editing technology to successfully block the transmission of the SARS-CoV-2 virus in infected human cells, according to research released recently that could pave the way for COVID-19 treatments.

Writing in the journal Nature Communications, researchers in Australia said the tool was effective against viral transmissions in lab tests, adding that they hoped to begin animal trials soon.

CRISPR, which allows scientists to alter DNA sequences and modify gene function, has already shown promise in eliminating the genetic coding that drives the development of children's cancer.

The team in Tuesday's study used an enzyme, CRISPR-Cas13b, that binds to relevant RNA sequences on the novel coronavirus and degrades the genome it needs to replicate inside human cells.

 The team had designed the CRISPR tool to recognize SARS-CoV-2, the virus responsibly for COVID-19.

Once the virus is recognized, the CRISPR enzyme is activated and chops up the virus.

Mohamed Fareh et al, Reprogrammed CRISPR-Cas13b suppresses SARS-CoV-2 replication and circumvents its mutational escape through mismatch tolerance, Nature Communications (2021). DOI: 10.1038/s41467-021-24577-9

https://phys.org/news/2021-07-gene-blocks-virus-transmission-human....

Quantum physics helps destroy cancer cells

Cancer cell death is triggered within three days when X-rays are focused on tumor tissue containing iodine-carrying nanoparticles. The iodine releases electrons that break the tumor's DNA, leading to cell death.

Exposing a metal to light leads to the release of electrons, a phenomenon called the photoelectric effect. An explanation of this phenomenon by Albert Einstein in 1905 heralded the birth of quantum physics. This research now research provides evidence that suggests it is possible to reproduce this effect inside cancer cells.

A longstanding problem with cancer radiation therapy is that it is not effective at the center of tumors, where oxygen levels are low due to the lack of deep-penetrating blood vessels. X-ray irradiation needs oxygen to generate DNA-damaging reactive oxygen when the rays hit molecules inside the cell.

Researchers have been trying to overcome this issue by finding more direct ways to damage cancer DNA. In earlier work, they showed that gadolinium-loaded nanoparticles could kill cancer cells when irradiated with 50.25 kiloelectron volts of synchrotron-generated X-rays.

In the current study, they designed porous, iodine-carrying organosilica nanoparticles. Iodine is cheaper than gadolinium and releases electrons at lower energy levels.

The researchers dispersed their nanoparticles through tumor spheroids, 3D tissue containing multiple cancer cells. Irradiating the spheroids for 30 minutes with 33.2 keV of X-rays led to their complete destruction within three days. By systematically changing energy levels, they were able to demonstrate that the optimum effect of tumor destruction occurs with 33.2 keV X-ray. Further analyses showed that the nanoparticles were taken up by the tumor cells, localizing just outside their nuclei. Shining just the right amount of X-ray energy onto the tissue prompted iodine to release electrons, which then caused double-strand breaks in the nuclear DNA, triggering cell death. 

Yuya Higashi et al, Iodine containing porous organosilica nanoparticles trigger tumor spheroids destruction upon monochromatic X-ray irradiation: DNA breaks and K-edge energy X-ray, Scientific Reports (2021). DOI: 10.1038/s41598-021-93429-9

https://phys.org/news/2021-07-quantum-physics-cancer-cells.html?utm...

New spray could someday help heal damage after a heart attack

Heart attack, or myocardial infarction, is one of the leading causes of death worldwide. Although modern surgical techniques, diagnostics and medications have greatly improved early survival from these events, many patients struggle with the long-term effects of permanently damaged tissue, and the 5-year mortality rate remains high. Now, researchers reporting in ACS Nano have developed a minimally invasive exosome spray that helped repair rat hearts after myocardial infarction.

The Story of Primary Plastid Endosymbiosis: How Algae and Plants became Photosynthetic

Glass octopus moving in the deep sea

Marine biologists spotted the elusive glass octopus (Vitreledonella richardi) during a 34-day expedition off the remote Phoenix Islands

Human cells harness power of detergents to wipe out bacteria

This killer cleaner, a protein known as APOL3, thwarts infections by dissolving bacterial membranes. Researchers tested the protein on the food-poisoning bacteria Salmonella and other similar microbes.

The work offers new insight into how human cells defend themselves against infection, a process termed cell-autonomous immunity. While scientists knew that cells could attack bacterial membranes, this study uncovers what appears to be the first example of a protective intracellular protein with detergent-like action.

"A human apolipoprotein L with detergent-like activity kills intracellular pathogens" Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abf8113

https://phys.org/news/2021-07-human-cells-harness-power-detergents....

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Thinking without a brain: Studies in brainless slime molds reveal that they use physical cues to decide where to grow

Scientists  have discovered that a brainless slime mold called Physarum polycephalum uses its body to sense mechanical cues in its surrounding environment, and performs computations similar to what we call "thinking" to decide in which direction to grow based on that information. Unlike previous studies with Physarum, these results were obtained without giving the organism any food or chemical signals to influence its behavior. The study is published in Advanced Materials.

Physarum is interesting because it doesn't have a brain but it can still perform a lot of the behaviours that we associate with thinking, like solving mazes, learning new things, and predicting events. Figuring out how proto-intelligent life manages to do this type of computation gives us more insight into the underpinnings of animal cognition and behavior, including our own.

The team's research demonstrated that this brainless creature was not simply growing toward the heaviest thing it could sense—it was making a calculated decision about where to grow based on the relative patterns of strain it detected in its environment.

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Slime molds are amoeba-like organisms that can grow to be up to several feet long, and help break down decomposing matter in the environment like rotting logs, mulch, and dead leaves. A single Physarum creature consists of a membrane containing many cellular nuclei floating within a shared cytoplasm, creating a structure called a syncytium. Physarum moves by shuttling its watery cytoplasm back and forth throughout the entire length of its body in regular waves, a unique process known as shuttle streaming. With most animals, we can't see what's changing inside the brain as the animal makes decisions. Physarum offers a really exciting scientific opportunity because we can observe its decisions about where to move in real-time by watching how its shuttle streaming behavior changes.

While previous studies have shown that Physarum moves in response to chemicals and light, Murugan and her team wanted to know if it could make decisions about where to move based on physical cues in its environment alone.

The researchers placed Physarum specimens in the center of petri dishes coated with a semi-flexible agar gel and placed either one or three small glass discs next to each other atop the gel on opposite sides of each dish. They then allowed the organisms to grow freely in the dark over the course of 24 hours, and tracked their growth patterns. For the first 12 to 14 hours, the Physarum grew outwards evenly in all directions; after that, however, the specimens extended a long branch that grew directly over the surface of the gel toward the three-disc region 70% of the time. Remarkably, the Physarum chose to grow toward the greater mass without first physically exploring the area to confirm that it did indeed contain the larger object.

Part 2: 

The researchers experimented with several variables to see how they impacted Physarum's growth decisions, and noticed something unusual: when they stacked the same three discs on top of each other, the organism seemed to lose its ability to distinguish between the three discs and the single disc. It grew toward both sides of the dish at roughly equal rates, despite the fact that the three stacked discs still had greater mass. Clearly, Physarum was using another factor beyond mass to decide where to grow.

To figure out the missing piece of the puzzle, the scientists used computer modeling to create a simulation of their experiment to explore how changing the mass of the discs would impact the amount of stress (force) and strain (deformation) applied to the semi-flexible gel and the attached growing Physarum. As they expected, larger masses increased the amount of strain, but the simulation revealed that the strain patterns the masses produced changed, depending on the arrangement of the discs.

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But how was it detecting these strain patterns? The scientists suspected it had to do with Physarum's ability to rhythmically contract and tug on its substrate, because the pulsing and sensing of the resultant changes in substrate deformation allows the organism to gain information about its surroundings. 

Advanced Materials (2021). DOI: 10.1002/adma.202008161

https://phys.org/news/2021-07-brain-brainless-slime-molds-reveal.ht...

Researchers create snake-venom-derived 'super glue' that stops bleeding in seconds 

This super glue is based on a new discovery on a blood clotting enzyme called reptilase or batroxobin found in the venom of lancehead snakes (Bothrops atrox), which are amongst the most poisonous snakes in South America.

Taking advantage of this clotting property, researchers designed a body tissue adhesive that incorporates the special enzyme into a modified gelatin that can be packaged into a small tube for easy, and potentially life-saving, application.

During trauma, injury and emergency bleeding, this 'super glue' can be applied by simply squeezing the tube and shining a visible light, such as a laser pointer, over it for few seconds. Even a smartphone flashlight will do the job.

Compared to clinical fibrin glue, considered the industry gold standard for clinical and field surgeons, the new tissue sealant has 10 times the adhesive strength to resist detachment or washout due to bleeding. The blood clotting time is also much shorter, cutting it in half from 90 seconds for fibrin glue to 45 seconds for the new snake venom "super glue."

This new biotechnology translates to less blood loss and more life-saving. The super-sealant was tested in models for deep skin cuts, ruptured aortae, and severely injured livers—all considered as major bleeding situations.

Yicheng Guo et al, Snake extract–laden hemostatic bioadhesive gel cross-linked by visible light, Science Advances (2021). DOI: 10.1126/sciadv.abf9635

https://phys.org/news/2021-07-snake-venom-derived-super-seconds-vis...

Researchers confirm we may never know how many species have inhabit...

Professors in Syracuse University's College of Arts and Sciences explored whether or not the scientific community will ever be able to settle on a 'total number' of species of living vertebrates, which could help with species preservation. By knowing what's out there, researchers argue that they can prioritize places and groups on which to concentrate conservation efforts.

Bruce H Wilkinson et al, Estimating vertebrate biodiversity using the tempo of taxonomy – a view from Hubbert's peak, Biological Journal of the Linnean Society (2021). DOI: 10.1093/biolinnean/blab080

‘Super-antibodies’ could curb COVID-19 and help avert future pandemics

Companies are designing next-generation antibodies modeled on those taken from unique individuals whose immune systems can neutralize any COVID-19 variant—and related coronaviruses, too.

A new generation of designer antibodies could help to treat a wide range of SARS-CoV-2 variants — and future coronaviruses with pandemic potential. ‘Super-antibodies’ are modelled on antibodies taken from rare individuals whose immune systems can neutralize any SARS-CoV-2 variant and related coronaviruses.

https://www.nature.com/articles/s41587-021-00980-x?utm_source=Natur...

Just 7% of our DNA is unique to modern humans, study shows

What makes humans unique? Scientists have taken another step toward solving an enduring mystery with a new tool that may allow for more precise comparisons between the DNA of modern humans and that of our extinct ancestors.

Just 7% of our genome is uniquely shared with other humans, and not shared by other early ancestors, according to a study published Friday in the journal Science Advances.

That's a pretty small percentage. This kind of finding is why scientists are turning away from thinking that we humans are so vastly different from Neanderthals.

The research draws upon DNA extracted from fossil remains of now-extinct Neanderthals and Denisovans dating back to around 40,000 or 50,000 years ago, as well as from 279 modern people from around the world.

Scientists already know that modern people share some DNA with Neanderthals, but different people share different parts of the genome. One goal of the new research was to identify the genes that are exclusive to modern humans.

It's a difficult statistical problem, and the researchers developed a valuable tool that takes account of missing data in the ancient genomes.

The researchers also found that an even smaller fraction of our genome—just 1.5%—is both unique to our species and shared among all people alive today. Those slivers of DNA may hold the most significant clues as to what truly distinguishes modern human beings.

Scientists now can tell those regions of the genome are highly enriched for genes that have to do with neural development and brain function.

Nathan K. Schaefer et al, An ancestral recombination graph of human, Neanderthal, and Denisovan genomes, Science Advances (2021). DOI: 10.1126/sciadv.abc0776

https://phys.org/news/2021-07-dna-unique-modern-humans.html?utm_sou...