Metal-ion breakthrough leads to new biomaterials

The elasticity of a biodegradable, metal-ion elastomer is demonstrated. The first-of-its-kind material, developed by engineers, can be used to repair skin, blood vessels and other soft tissue.

Physicists Have Successfully Connected Two Large Objects in Quantum Entanglement

Physicists have just served up a sharp reminder that even our macroscopic world is subject to the laws of quantum physics - by successfully entangling a millimetre-sized drum with a large cloud of atoms. 

They conducted the experiment using a 13 nanometre-thick, millimetres-long silicon nitride membrane (or drum) that buzzed lightly when struck with photons.

Those photons, or particles of light, came courtesy of a thin fog of a billion caesium atoms spinning inside the confines of a small, cold cell.

Despite being two very different objects, the millimetres-long drum and the fog of atoms represent an entangled system - and they push the limits of quantum mechanics. With the new result, entanglement between very different objects has become possible

Entanglement between distant macroscopic mechanical and spin systems

https://www.nature.com/articles/s41567-020-1031-5

Meet the real-life superhumans pushing the limits of human ability

A new thermometer measures temperature with sound

prediction errors that can influence human perceptions of time

Humans can sometimes perceive the passing of time differently, for instance, feeling as though an hour passed very quickly or that a few minutes went by extremely slowly. This suggests that the human perception of time is subjective and can be affected by many factors that can cause people to perceive the same amount of time as longer or shorter than it actually is.

Researchers have recently carried out a fascinating study exploring if and how prediction errors can bias how different individuals perceive the passing of time. This study shows that time perception can be influenced by both positive and negative prediction errors, while also identifying the putamen as a brain region responsible for biased time perception. Dopaminergic brain activation in a structure called the basal ganglia (BG) is known to be related to reinforcement learning in general, and reward prediction errors processing in particular. BG activation is also related to time perception required for motor functions that our brain controls.

For many years, time perception and human prediction errors were seen as almost entirely independent processes. This study  challenges this idea, suggesting that these two elements are, in fact, deeply interlinked.

Ido Toren et al. Prediction errors bidirectionally bias time perception, Nature Neuroscience (2020). DOI: 10.1038/s41593-020-0698-3

https://medicalxpress.com/news/2020-10-exploring-errors-human-perce...

Squeezing light: Developing an integrated nanophotonic device to generate squeezed light

In a recent report published scientists measured the quadrature-squeezed vacuum and photon number difference generated within an integrated nanophotonic device. The results will impact applications in quantum technology.

The concept of squeezed light is relevant in quantum optical processing, where the associated architectures of continuous variable photonics demand high-quality, scalable devices to generate squeezed light for many fundamental photonic quantum information processing applications. Examples include continuous variable (CV) quantum computation and Gaussian boson sampling, which is a promising avenue to achieve near-thermal quantum advantage and accommodate a range of intriguing concepts, including molecular vibronic spectrum simulations, graph isomorphism, perfect matchings and graph similarity.

Most of these quantum applications require a scalable source of squeezed light to implement and enhance optical sensing near the quantum limit. Integrated photonics is a natural platform to explore these scalable squeezed light sources, where the stability and high-throughput manufacturability offered by modern lithographic (patterning) methods present promising pathways to realize useful quantum technologies at scale. However, progress to date on chip-integrated squeezing is limited. In the present study, therefore, Vaidya et al. used spontaneous four-wave mixing (SWFM) in silicon nitride microring resonators to provide a readily accessible and mature technology on commercial fabrication platforms.

 V. D. Vaidya et al. Broadband quadrature-squeezed vacuum and nonclassical photon number correlations from a nanophotonic device, Science Advances (2020). DOI: 10.1126/sciadv.aba9186

Craig S. Hamilton et al. Gaussian Boson Sampling, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.170501

David J. Moss et al. New CMOS-compatible platforms based on silicon nitride and Hydex for nonlinear optics, Nature Photonics (2013). DOI: 10.1038/nphoton.2013.183

https://phys.org/news/2020-10-nanophotonic-device.html?utm_source=n...

The principle of superhabitable planets

Some planets may be better for life than Earth

Earth is not necessarily the best planet in the universe. Researchers have identified two dozen planets outside our solar system that may have conditions more suitable for life than our own. Some of these orbit stars that may be better than even our sun.

The details characteristics of potential "superhabitable" planets published: planets those that are older, a little larger, slightly warmer and possibly wetter than Earth. Life could also more easily thrive on planets that circle more slowly changing stars with longer lifespans than our sun.

While the sun is the center of our solar system, it has a relatively short lifespan of less than 10 billion years. Since it took nearly 4 billion years before any form of complex life appeared on Earth, many similar stars to our sun, called G stars, might run out of fuel before complex life can develop.

systems with K dwarf stars, which are somewhat cooler, less massive and less luminous than our sun. K stars have the advantage of long lifespans of 20 billion to 70 billion years. This would allow orbiting planets to be older as well as giving life more time to advance to the complexity currently found on Earth. However, to be habitable, planets should not be so old that they have exhausted their geothermal heat and lack protective geomagnetic fields. Earth is around 4.5 billion years old, but the researchers argue that the sweet spot for life is a planet that is between 5 billion to 8 billion years old.

Size and mass also matter. A planet that is 10% larger than the Earth should have more habitable land. One that is about 1.5 times Earth's mass would be expected to retain its interior heating through radioactive decay longer and would also have a stronger gravity to retain an atmosphere over a longer time period.

Water is key to life and the authors argue that a little more of it would help, especially in the form of moisture, clouds and humidity. A slightly overall warmer temperature, a mean surface temperature of about 5 degrees Celsius (or about 8 degrees Fahrenheit) greater than Earth, together with the additional moisture, would be also better for life. This warmth and moisture preference is seen on Earth with the greater biodiversity in tropical rain forests than in colder, drier areas.

Dirk Schulze-Makuch et al, In Search for a Planet Better than Earth: Top Contenders for a Superhabitable World, Astrobiology (2020). DOI: 10.1089/ast.2019.2161

https://phys.org/news/2020-10-planets-life-earth.html?utm_source=nw...

3 win Nobel medicine prize for discovering hepatitis C virus

Three scientists won the Nobel Prize in medicine this year for discovering the liver-ravaging hepatitis C virus, a breakthrough that led to cures for the deadly disease and tests to keep the scourge out of the blood supply.

Harvey J. Alter and Charles M. Rice and  Michael Houghton were honoured for their work over several decades on an illness that still plagues more than 70 million worldwide and kills over 400,000 each year. Their work led to .... in the words of Nobel committee 'for the first time in history, the disease can now be cured, raising hopes of eradicating hepatitis C virus from the world'. 

Nanoparticles can turn off genes in bone marrow cells

Using specialized nanoparticles, MIT engineers have developed a way to turn off specific genes in cells of the bone marrow, which play an important role in producing blood cells. These particles could be tailored to help treat heart disease or to boost the yield of stem cells in patients who need stem cell transplants, the researchers say.

This type of genetic therapy, known as RNA interference, is usually difficult to target to organs other than the liver, where nanoparticles would tend to accumulate. The MIT researchers were able to modify their particles in such a way that they would accumulate in the cells found in the bone marrow. "If we can get these particles to hit other organs of interest, there could be a broader range of disease applications to explore, and one that we were really interested in this paper was the bone marrow. The bone marrow is a site for hematopoiesis of blood cells, and these give rise to a whole lineage of cells that contribute to various types of diseases. In a study of mice, the researchers showed that they could use this approach to improve recovery after a heart attack by inhibiting the release of bone marrow blood cells that promote inflammation and contribute to heart disease. -- RNA interference is a strategy that could potentially be used to treat a variety of diseases by delivering short strands of RNA that block specific genes from being turned on in a cell. So far, the biggest obstacle to this kind of therapy has been the difficulty in delivering it to the right part of the body. When injected into the bloodstream, nanoparticles carrying RNA tend to accumulate in the liver, which some biotech companies have taken advantage of to develop new experimental treatments for liver disease.

Nanoparticle-encapsulated siRNAs for gene silencing in the haematopoietic stem-cell niche, Nature Biomedical Engineering (2020). DOI: 10.1038/s41551-020-00623-7 , www.nature.com/articles/s41551-020-00623-7

https://phys.org/news/2020-10-nanoparticles-genes-bone-marrow-cells...

Neuroscientists discover a molecular mechanism that allows memories to form

When the brain forms a memory of a new experience, neurons called engram cells encode the details of the memory and are later reactivated whenever we recall it. A new  study reveals that this process is controlled by large-scale remodeling of cells' chromatin.

This remodeling, which allows specific genes involved in storing memories to become more active, takes place in multiple stages spread out over several days. Changes to the density and arrangement of chromatin, a highly compressed structure consisting of DNA and proteins called histones, can control how active specific genes are within a given cell.

This paper is the first to really reveal this very mysterious process of how different waves of genes become activated, and what is the epigenetic mechanism underlying these different waves of gene expression.

Engram cells are found in the hippocampus as well as other parts of the brain. Many recent studies have shown that these cells form networks that are associated with particular memories, and these networks are activated when that memory is recalled. However, the molecular mechanisms underlying the encoding and retrieval of these memories are not well-understood.

Neuroscientists know that in the very first stage of memory formation, genes known as immediate early genes are turned on in engram cells, but these genes soon return to normal activity levels.

The formation and preservation of memory is a very delicate and coordinated event that spreads over hours and days, and might be even months—we don't know for sure," Marco says. "During this process, there are a few waves of gene expression and protein synthesis that make the connections between the neurons stronger and faster."

Tsai and Marco hypothesized that these waves could be controlled by epigenomic modifications, which are chemical alterations of chromatin that control whether a particular gene is accessible or not. Previous studies from Tsai's lab have shown that when enzymes that make chromatin inaccessible are too active, they can interfere with the ability to form new memories. Many of the genes turned on during memory recall are involved in promoting protein synthesis at the synapses, helping neurons strengthen their connections with other neurons. The researchers also found that the neurons' dendrites—branched extensions that receive input from other neurons—developed more spines, offering further evidence that their connections were further strengthened.

The study is the first to show that memory formation is driven by epigenomically priming enhancers to stimulate gene expression when a memory is recalled.

 Mapping the epigenomic and transcriptomic interplay during memory formation and recall in the hippocampal engram ensemble, Nature Neuroscience (2020). DOI: 10.1038/s41593-020-00717-0 , www.nature.com/articles/s41593-020-00717-0

https://medicalxpress.com/news/2020-10-neuroscientists-molecular-me...

Normally an insulator, diamond becomes a metallic conductor when subjected to large strain in a new theoretical model

Long known as the hardest of all natural materials, diamonds are also exceptional thermal conductors and electrical insulators. Now, researchers have discovered a way to tweak tiny needles of diamond in a controlled way to transform their electronic properties, dialing them from insulating, through semiconducting, all the way to highly conductive, or metallic. This can be induced dynamically and reversed at will, with no degradation of the diamond material.

The research may open up a wide array of potential applications, including new kinds of broadband solar cells, highly efficient LEDs and power electronics, and new optical devices or quantum sensors.

The methods demonstrated in this work could be applied to a broad range of other semiconductor materials of technological interest in mechanical, microelectronics, biomedical, energy and photonics applications, through strain engineering.

Zhe Shi el al., "Metallization of diamond," PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2013565117

https://phys.org/news/2020-10-scientists-electrifying-diamond.html?...

**Scientists find evidence of exotic state of matter in candidate material for quantum computers

Using a novel technique, scientists have found evidence for a quantum spin liquid, a state of matter that is promising as a building block for the quantum computers of tomorrow.

Researchers discovered the exciting behavior while studying the so-called electron spins in the compound ruthenium trichloride. The findings show that electron spins interact across the material, effectively lowering the overall energy. This type of behaviour—consistent with a quantum spin liquid—was detected in ruthenium trichloride at high temperatures and in high magnetic fields.

K. A. Modic et al, Scale-invariant magnetic anisotropy in RuCl3 at high magnetic fields, Nature Physics (2020). DOI: 10.1038/s41567-020-1028-0

https://phys.org/news/2020-10-scientists-evidence-exotic-state-cand...

World's first direct observation of the magneto-Thomson effect

Applying a temperature gradient and a charge current to an electrical conductor leads to the release and absorbtion of heat. This is called the Thomson effect. In a first, researchers have directly observed the magneto-Thomson effect, which is the magnetic-field-induced modulation of the Thomson effect. This success may contribute to the development of new functions and technologies for thermal energy management and to advances in fundamental physics and materials .

science on magneto-thermoelectric conversion.

Kelly Morrison et al. Thermal Imaging of the Thomson Effect, Physics (2020). DOI: 10.1103/Physics.13.137

https://phys.org/news/2020-10-world-magneto-thomson-effect.html?utm...

Dozens of mammals could be susceptible to SARS-CoV-2

Numerous animals may be vulnerable to SARS-CoV-2, the virus that causes COVID-19, according to a large study modelling how the virus might infect different animals' cells, led by UCL researchers.

The study, published in Scientific Reports, reports evidence that 26 animals regularly in contact with people may be susceptible to infection.

The researchers investigated how the spike protein from SARS-CoV-2 could interact with the ACE2 protein it attaches to when it infects people.

The focus of the investigation was whether mutations in the ACE2 protein in 215 different animals, that make it different from the human version, would reduce the stability of the binding complex between the virus protein and host protein. Binding to the protein enables the virus to gain entry into host cells; while it is possible the virus might be able to infect animals via another pathway, it is unlikely based on current evidence that the virus could infect an animal if it cannot form a stable binding complex with ACE2.

The researchers found that for some animals, such as sheep and great apes (chimpanzee, gorilla, orangutan, and bonobo, many of which are endangered in the wild), the proteins would be able to bind together just as strongly as they do when the virus infects people. Some of the animals, such as sheep, have not yet been studied with infection tests, so this does not confirm that the animal can indeed be infected.

Scientific Reports (2020). DOI: 10.1038/s41598-020-71936-5

https://phys.org/news/2020-10-dozens-mammals-susceptible-sars-cov-....

Why do mirrors flip horizontally (but not vertically)?

Here's The Physics

**T Cells and Neurons Talk to Each Other

Post-viral fatigue syndrome- the condition affecting some COVID-19 survivors

https://theconversation.com/what-is-post-viral-fatigue-syndrome-the...

3 scientists win Nobel physics prize for black hole research

Three scientists won the Nobel Prize in physics Tuesday for advancing our understanding of Krishna (means ‘black’ in Sanskrit :)) holes.

Roger Penrose, Reinhard Genzel and Andrea Ghez explained to the world these dead ends of the cosmos that devour light and even time. Staples of both science fact and fiction, black holes are still not completely understood but are deeply connected, somehow, to the creation of galaxies, where the stars and life exist.

Penrose, of the University of Oxford, received half of the prize for discovering that Albert Einstein's general theory of relativity predicts the formation of black holes.

Announcement of the 2020 Nobel Prize in Physics

Deciphered: evolution of the Y chromosome in great apes 

New analysis of the DNA sequence of the male-specific Y chromosomes from all living species of the great ape family helps to clarify our understanding of how this enigmatic chromosome evolved. A clearer picture of the evolution of the Y chromosome is important for studying male fertility in humans as well as our understanding of reproduction patterns and the ability to track male lineages in the great apes, which can help with conservation efforts for these endangered species.

A team of biologists and computer scientists sequenced and assembled the Y chromosome from orangutan and bonobo and compared those sequences to the existing human, chimpanzee, and gorilla Y sequences. From the comparison, the team were able to clarify patterns of evolution that seem to fit with behavioural differences between the species and reconstruct a model of what the Y chromosome might have looked like in the ancestor of all great apes.

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The Y chromosome is important for male fertility and contains the genes critical for sperm production, but it is often neglected in genomic studies because it is so difficult to sequence and assemble . The Y chromosome contains a lot of repetitive sequences, which are challenging for DNA sequencing, assembling sequences, and aligning sequences for comparison. There aren't out-of-the-box software packages to deal with the Y chromosome, so we had to overcome these hurdles and optimize our experimental and computational protocols, which allowed us to address interesting biological questions.

The Y chromosome is unusual. It contains relatively few genes, many of which are involved in male sex determination and sperm production; large sections of repetitive DNA, short sequences repeated over and over again; and large DNA palindromes, inverted repeats that can be many thousands of letters long and read the same forwards and backwards.

Previous work by the team comparing human, chimpanzee, and gorilla sequences had revealed some unexpected patterns. Humans are more closely related to chimpanzees, but for some characteristics, the human Y was more similar to the gorilla Y.

Monika Cechova et al, Dynamic evolution of great ape Y chromosomes, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.2001749117

https://phys.org/news/2020-10-evolution-chromosome-great-apes-decip...

**Individual suicide risk can be dramatically altered by social 'sameness,' study finds

Similarities among individuals living in the same communities can dramatically change their risk of dying by suicide, according to a new study

Bernice A. Pescosolido et al, Cross-level sociodemographic homogeneity alters individual risk for completed suicide, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.2006333117

https://phys.org/news/2020-10-individual-suicide-social-sameness.ht...

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Safeguarding iconic buildings from bomb explosions

 Researchers have developed a technique to prevent glass facades on iconic buildings from shattering if the building is targeted by terrorists in a bomb explosion.

In the study researchers looked at the "maximum credible load" of an explosion and how to minimize the problem of a deadly wave of shattered glass which can cause traumatic injury and death.

The study went beyond previous research in the field with a sophisticated coupling analysis, which did not just look at the way the glass responds to an explosion but also modeled the explosive source, the pressure wave transmission and fluid-structure interaction.

The researchers modeled the shock waves that traveled through the air and then they studied how it hit the structures.

The solution is to absorb the energy of the blast with a shock absorbing layer between the glass panels in the laminated glass and through the members of the supporting system as well as to make the cable trusses stronger. The glass is certainly going to crack, but this interlayer holds the particles together.

 R.R.C. Piyasena et al. Fully coupled modeling technique for blast analysis of cable truss facades, Engineering Failure Analysis (2020). DOI: 10.1016/j.engfailanal.2020.104771

https://techxplore.com/news/2020-10-safeguarding-iconic-explosions....

**A new interpretation of quantum mechanics suggests that reality does not depend on the person measuring it

Quantum mechanics arose in the 1920s, and since then scientists have disagreed on how best to interpret it. Many interpretations, including the Copenhagen interpretation presented by Niels Bohr and Werner Heisenberg, and in particular, von Neumann-Wigner interpretation, state that the consciousness of the person conducting the test affects its result. On the other hand, Karl Popper and Albert Einstein thought that an objective reality exists. Erwin Schrödinger put forward the famous thought experiment involving the fate of an unfortunate cat that aimed to describe the imperfections of quantum mechanics.

In their most recent article, Finnish civil servants Jussi Lindgren and Jukka Liukkonen, who study quantum mechanics in their free time, take a look at the uncertainty principle that was developed by Heisenberg in 1927. According to the traditional interpretation of the principle, location and momentum cannot be determined simultaneously to an arbitrary degree of precision, as the person conducting the measurement always affects the values.

However, in their study Lindgren and Liukkonen concluded that the correlation between a location and momentum, i.e., their relationship, is fixed. In other words, reality is an object that does not depend on the person measuring it. Lindgren and Liukkonen utilized stochastic dynamic optimization in their study. In their theory's frame of reference, Heisenberg's uncertainty principle is a manifestation of thermodynamic equilibrium, in which correlations of random variables do not vanish.

"The results suggest that there is no logical reason for the results to be dependent on the person conducting the measurement. According to our study, there is nothing that suggests that the consciousness of the person would disturb the results or create a certain result or reality

This interpretation supports such interpretations of quantum mechanics that support classical scientific principles.

"The interpretation is objective and realistic, and at the same time as simple as possible. We like clarity and prefer to remove all mysticism

Jussi Lindgren et al. The Heisenberg Uncertainty Principle as an Endogenous Equilibrium Property of Stochastic Optimal Control Systems in Quantum Mechanics, Symmetry (2020). DOI: 10.3390/sym12091533

https://phys.org/news/2020-10-quantum-mechanics-reality-person.html...

Researchers crack quantum physics puzzle

Scientists have re-investigated a sixty-year-old idea by an American physicist and provided new insights into the quantum world.

The research could lead to improved spectroscopic techniques, laser techniques, interferometric high-precision measurements and atomic beam applications.

Quantum physics is the study of everything around us at the atomic level, atoms, electrons and particles. Atoms and electrons which are so small, one billion placed side by side could fit within a centimeter. Because of the way atoms and electrons behave, scientists describe their behaviour as like waves.

Waves, unlike particles which travel in straight lines, can go around obstacles, but if there are enough random obstacles, the waves cannot get through because they interfere with each other and cancel themselves out.

At low temperatures, matter, which is made up of atoms and particles, can be made to behave much like light; that is, light behaves the same way all waves do whether it be light waves or ocean waves. In its interaction with matter, light can behave like it is composed of particles which don't go around objects but instead travel in a straight line.

In the Quantum Information Lab researchers took this one step further and added an ultra-cold atom experiment to the mix. With the aid of high tech lasers, they manipulated these ultra-cold atoms until they were so cold, their wave behaviour became visible to the eye.

This is about a billionth of a degree above absolute zero (-273.15 degrees C) so that is pretty chilly. Physicists have created customized patterns of obstacles to stop the waves, and when they take a picture, they can find out where these atoms are. This way, they can see what exactly is required to get their quantum-mechanical waves to reflect off obstacles, and why the waves do not get in.

Donald H. White et al. Observation of two-dimensional Anderson localisation of ultracold atoms, Nature Communications (2020). DOI: 10.1038/s41467-020-18652-w

https://phys.org/news/2020-10-quantum-physics-puzzle.html?utm_sourc...

Scientists unravel the mystery behind new plant species found in the Swiss Alps, which only took 150 years to evolve

A new plant species in Swiss alps Cardamine insueta

took only 150years to evolve. Scientists think this is because of traits C. insueta inherited from its parent plants - each with its own distinct habitat. Depending on the environmental situation, the plant activates a different set of genes it inherited from its two parent species.

https://www.frontiersin.org/articles/10.3389/fgene.2020.567262/full
https://www.businessinsider.in/science/biology/news/new-swiss-alps-...

Study solves an HIV mystery

In some patients with HIV who take medication, the virus still shows up in their blood. A study  has found “repliclones”—large clones of HIV-infected cells that produce infectious virus particles—are to blame.

A patient with HIV who insists they are adhering to the daily medication regimen meant to keep the virus in check, but testing says otherwise. It seems the virus is still showing up in the patient’s blood, which clinicians thought couldn’t happen when the infection is controlled with medication. scientists report that they’ve solved the mystery—and the answer has clinical implications.

In a study  infectious disease researchers show that the issue isn’t nonadherence to medication or resistance to the drugs. Instead, the patients are victims of what the scientists have dubbed “repliclones”—large clones of HIV-infected cells that produce infectious virus particles.

Repliclones can grow large enough and produce enough virus to make it appear that antiretroviral therapy isn’t working completely even when it is.--

In short, rather than the virus infecting new cells, already infected HIV-producing cells are growing into large clones that make and release virus. Current medications for HIV infection block the virus from infecting new cells but don’t affect virus production from cells or clones of cells that are already infected.

HIV replicates by taking over a cell’s machinery and using it to produce more virus, which can then go on to infect other cells. Antiretroviral therapy, which is taken daily, prevents the virus from infecting new cells. So, even though HIV can’t yet be cured, it can be controlled to the point that it isn’t detectable in blood tests.

https://www.upmc.com/media/news/100520-mellors-replicones

https://researchnews.cc/news/2885/Study-solves-an-HIV-mystery#.X31H...

Himalayan glaciers melting because of high-altitude dust

Desert dust from as far away as Saudi Arabia gets picked up by winds that carry it to the snowpack of the Himalayas, where it accelerates glacial warming and snowmelt, scientists say. 

Himalayan glaciers melting because of high-altitude dust

Quantum heat engine behaviour observed in a qubit

Although many of today's accepted theories of classical thermodynamics predate even the industrial revolution they helped to propel, many open questions remain around how these ideas translate to the level of single quantum systems. In particular, the potential for superposition of states has as yet unexplored implications for thermodynamic behavior. Now, a collaboration of researchers has produced a quantum device that can not only behave analogously to a heat engine and a refrigerator, but also a superposition of both at the same time.

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They came together to examine the behavior of qubits based on impurities in silicon for quantum interferometry before turning their attention to how the behavior of these systems might resemble classical heat engines.

 K. Ono et al. Analog of a quantum heat engine using a single-spin qubit, Physical Review Letters (2020). Accepted manuscript: journals.aps.org/prl/accepted/ … b682605ce40bdae2719c

https://phys.org/news/2020-10-quantum-behaviour-qubit.html?utm_sour...

2 scientists win Nobel chemistry prize for gene-editing tool

The Nobel Prize in chemistry went to two researchers Wednesday for a gene-editing tool that has revolutionized science by providing a way to alter DNA, the code of life—technology already being used to try to cure a host of diseases and raise better crops and livestock.

Emmanuelle Charpentier  and Jennifer A. Doudna  won for developing CRISPR-cas9, a very simple technique for cutting a gene at a specific spot, allowing scientists to operate on flaws that are the root cause of many diseases.

Announcement of the 2020 Nobel Prize in Chemistry

https://phys.org/news/2020-10-nobel-prize-chemistry-awarded-charpen...

Scientists clarify how the brain separates present from past dangers

A team of neuroscientists has identified processes the brain undergoes to distinguish real and present dangers from those linked to past experiences in mice. The findings have implications for our understanding of post-traumatic stress disorder (PTSD)—an affliction marked by the inability to distinguish between past and present dangers or to recognize "safe" situations.

Memories of a traumatic episode can last for a long time. But we are able to use such memories selectively: to predict and respond to a subsequent, related danger while also recognizing when threats do not exist. This is especially important for survival behaviour in an uncertain environment such as a conflict zone or at times of social unrest.

This has significant implications for memory disorders such as PTSD, where patients have difficulty distinguishing between safety and threat cues.

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Learning to identify and appropriately respond to cues in an uncertain environment is crucial for animal survival, the researchers note. Specifically, cues that reliably predict danger prompt behaviors such as freezing in order to escape detection. However, along with the threat-predicting cues, an uncertain environment can present cues that predict safety—or, specifically, lack of danger. Animals, then, need to respond to the threat-predicting cue with defensive behaviors and, conversely, to safety cues by ceasing a threat response and resuming normal behaviors.

 the scientists sought to identify the cellular molecules, or substrates, for long-term storage of threat and safety-cue-associated memories.

It has been long established that a region of the brain, the amygdala, plays a fundamental role in the processing and storing of emotion-related information. Less understood, however, are the cellular engines and architecture that underlie it—specifically, the identity of cell types that store cue-related information and allow animals to respond appropriately even after considerable time has elapsed after the initial threat exposure.

Also well understood are the formation and consolidation of long-lasting memories, which occur through changes in the cellular landscape of proteins—a dynamic that captures significant features of an event, in part by synthesis of new proteins.

In the new work, the scientists aimed to better understand these mechanisms by disrupting key steps in protein synthesis in specific cell types—a maneuver that would reveal their significance. This procedure allowed the researchers to identify key players in this intricate process.

Amygdala inhibitory neurons as loci for translation in emotional memories, Nature (2020). DOI: 10.1038/s41586-020-2793-8 , www.nature.com/articles/s41586-020-2793-8

https://medicalxpress.com/news/2020-10-scientists-brain-dangers.htm...

Traveling brain waves help detect hard-to-see objects

Imagine that you're late for work and desperately searching for your car keys. You've looked all over the house but cannot seem to find them anywhere. All of a sudden you realize your keys have been sitting right in front of you the entire time. Why didn't you see them until now?

A team of scientists has uncovered details of the neural mechanisms underlying the perception of objects. They found that patterns of neural signals, called traveling brain waves, exist in the visual system of the awake brain and are organized to allow the brain to perceive objects that are faint or otherwise difficult to see.

They have discovered that faint objects are much more likely to be seen if visualizing the object is timed with the traveling brain waves. The waves actually facilitate perceptual sensitivity, so there are moments in time when you can see things that you otherwise could not. It turns out that these traveling brain waves are an information-gathering process leading to the perception of an object.

They found that the brain's ability to recognize targets was directly related to when and where the traveling brain waves occurred in the visual system: when the traveling waves aligned with the stimulus. There is a spontaneous level of activity in the brain that appears to be regulated by these traveling waves.

Spontaneous travelling cortical waves gate perception in behaving primates, Nature (2020). DOI: 10.1038/s41586-020-2802-y , www.nature.com/articles/s41586-020-2802-y

https://medicalxpress.com/news/2020-10-brain-hard-to-see.html?utm_s...

Extremely rare Higgs boson decay process spotted

The Higgs boson reached overnight fame in 2012 when it was finally discovered in a jumble of other particles generated at CERN's Large Hadron Collider (LHC) in Geneva, Switzerland. The discovery was monumental because the Higgs boson, which had only been theorized about previously, has the special property of endowing other elementary particles with mass. It is also exceedingly rare and difficult to identify in the debris of colliding particles.

Caltech physicists played a major role in the Higgs boson discovery, a result that earned theoretical physicist Peter Higgs a share of the 2013 Nobel Prize in Physics, and now they continue to make significant findings about rare Higgs boson processes.

This summer, for the first time, particle physicists using data collected by the experiment known as the Compact Muon Solenoid (CMS) at the LHC, have found evidence that the Higgs boson decays into a pair of elementary particles called muons. The muon is a heavier version of the electron, and both muons and electrons belong to a class of particles known as fermions, as described in the widely accepted model of particles called the Standard Model. The Standard Model classifies all particles as either fermions or bosons. Generally, fermions are building blocks of all matter, and bosons are the force carriers.

A muon is also what is known as a second-generation particle. First-generation fermion particles such as electrons are the lightest of particles; second- and third-generation particles can decay to become first-generation particles. The new finding represents the first evidence that the Higgs boson interacts with second-generation fermions.

In addition, this result provides further evidence that the decay rate of the Higgs to fermion pairs is proportional to the square of the mass of the fermion. This is a key prediction of the Higgs theory. With more data, the LHC experiments are expected to confirm that indeed the Higgs gives the fundamental particles their mass.

Joseph Lykken et al. The future of the Higgs boson, Physics Today (2013). DOI: 10.1063/PT.3.2212

https://phys.org/news/2020-10-extremely-rare-higgs-boson.html?utm_s...

Aerodynamicists reveal link between fish scales and aircraft drag

Reducing drag means faster aircraft speeds and less fuel consumption this is an important area of study for aerodynamicists

Through their biomimetic study, Professor Bruecker's team has discovered that the fish-scale array produces a zig-zag motion of fluid in overlapping regions of the surface of the fish, which in turn causes periodic velocity modulation and a streaky flow that can eliminate Tollmien-Schlichting wave induced transition to reduce skin friction drag by more than 25 percent.

An examination of oil flow visualization using computational fluid dynamics (CFD) on sea bass and common carp enabled the authors to come up with a working hypothesis:

"Computation Fluid Dynamics (CFD) was used to study the flow pattern over the surface and revealed a hitherto unknown effect of the scales as a mechanism to generate a regular pattern of parallel streamwise velocity streaks in the boundary layer. To prove their existence also on the real fish skin, oil flow visualization was done on sea bass and common carp, which indeed confirmed their presence in a regular manner along their real body, with the same arrangement relative to the scale array as observed along the biomimetic surface. These results let the authors hypothesize about a possible mechanism for transition delay, inspired by various previous fundamental transition studies, where streaky structures generated by cylindrical roughness elements or vortex generator arrays have shown a delay of transition."

**Aerodynamicists reveal link between fish scales and aircraft drag

Reducing drag means faster aircraft speeds and less fuel consumption this is an important area of study for aerodynamicists

Through their biomimetic study, Professor Bruecker's team has discovered that the fish-scale array produces a zig-zag motion of fluid in overlapping regions of the surface of the fish, which in turn causes periodic velocity modulation and a streaky flow that can eliminate Tollmien-Schlichting wave induced transition to reduce skin friction drag by more than 25 percent.

An examination of oil flow visualization using computational fluid dynamics (CFD) on sea bass and common carp enabled the authors to come up with a working hypothesis:

"Computation Fluid Dynamics (CFD) was used to study the flow pattern over the surface and revealed a hitherto unknown effect of the scales as a mechanism to generate a regular pattern of parallel streamwise velocity streaks in the boundary layer. To prove their existence also on the real fish skin, oil flow visualization was done on sea bass and common carp, which indeed confirmed their presence in a regular manner along their real body, with the same arrangement relative to the scale array as observed along the biomimetic surface. These results let the authors hypothesize about a possible mechanism for transition delay, inspired by various previous fundamental transition studies, where streaky structures generated by cylindrical roughness elements or vortex generator arrays have shown a delay of transition."

New research: nitrous oxide emissions 300 times more powerful than CO₂ are jeopardising Earth’s future

Nitrous oxide from agriculture and other sources is accumulating in the atmosphere so quickly it puts Earth on track for a dangerous 3℃ warming this century,  new research has found.

This colossal amount of nitrogen makes crops and pastures grow more abundantly. But it also releases nitrous oxide (N₂O), a greenhouse gas.

The study found that N₂O emissions from natural sources, such as soils and oceans, have not changed much in recent decades. But emissions from human sources have increased rapidly.

Agriculture caused almost 70% of global N₂O emissions in the decade to 2016. The emissions are created through microbial processes in soils. The use of nitrogen in synthetic fertilisers and manure is a key driver of this process.

Other human sources of N₂O include the chemical industry, waste water and the burning of fossil fuels.

https://theconversation.com/new-research-nitrous-oxide-emissions-30...

https://www.sciencealert.com/a-bacterial-clone-is-behind-a-concerni...

2,500 y/o mummy in "perfect condition" revealed after discovery of 59 sarcophagi

https://www.youtube.com/watch?v=7sd0BomMDDk&feature=emb_logo

Neurobiology of conversation: Brain activity depends on who you're talking to

Our brains respond differently when talking to a person from a different socioeconomic group than during a conversation with someone of a similar background, a novel new imaging study shows.

While neuroscientists have used brain imaging scans to track in great detail neural responses of individuals to a host of factors such as stress, fear, addiction, and even love and lust, new research shows what happens in the brains of two individuals engaged in a simple social interaction.

The study reveals the distinct neurobiology of a conversation between two people of different backgrounds.

When a  professor talks to a homeless person, his or her frontal lobe activates a different neural network than if they were chatting with another colleague. Our brain has apparently designed a frontal lobe system that helps us deal with our diversity.

The researchers found that in both subjects the activity in the left dorsolateral prefrontal cortex, which is involved in control of cognitive processes, was much higher when they talked with someone from a different socioeconomic background than with someone of similar status.

There is a neurobiology of socialness, and neurobiology allows us to modulate our response to diversity.  We want to be inclusive, we want equity, and theoretically, neuroscience can say something about how we can achieve that.

https://news.yale.edu/2020/10/05/neurobiology-conversation-brain-ac...

https://researchnews.cc/news/2902/Neurobiology-of-conversation--Bra...

Study Points to Novel Role for Microglia in Down Syndrome

New method can pinpoint cracks in metal long before they cause catastrophes

Fatigue failure plagues all metals and mitigating it is of great importance.

It is the leading cause of cracks in metallic components of aircraft.

That is why it is common practice in the airline industry to adhere to regular—and expensive—replacement schedules for many parts. But the life of those parts could be more accurately determined by better understanding the origins of crack initiation.

Whether it is the pounding of vehicles on bridges or shifts in air pressure on airplanes, such continuous change called "cyclic loading" gradually induces slips in the internal molecular structure of the most durable metals until cracks occur that could have been anticipated long before their perilous appearance.

With the lack of understanding of the mechanisms that lead to crack initiation, it has been difficult to predict with any reasonable accuracy the remaining life of a cyclically loaded material. The component could actually be fine and never fail but they throw it away anyway solely on the bases of statistical arguments. That's a huge waste of money.

Most current tests to understand the origins of crack initiation have focused on the moments just prior to or after cracking to assess what happened in the makeup of the metal. And many of those tests use far larger samples that preclude tracking the initiation of damage, which is a sub-micrometer scale feature. The new method narrows the lens as small as feasible and begins when metals are first exposed to loads that lead to localized damage that could become cracks.

 "The heterogeneity of persistent slip band nucleation and evolution in metals at the micrometer scale" Science (2020). science.sciencemag.org/cgi/doi … 1126/science.abb2690

https://phys.org/news/2020-10-method-metal-catastrophes.html?utm_so...

Generating photons for communication in a quantum computing system

Researchers using superconducting quantum bits connected to a microwave transmission line have shown how the qubits can generate on demand the photons, or particles of light, necessary for communication between quantum processors.

The advance is an important step toward achieving the interconnections that would allow a modular quantum computing system to perform operations at rates exponentially faster than classical computers can achieve.

 B. Kannan et al. Generating spatially entangled itinerant photons with waveguide quantum electrodynamics, Science Advances (2020). DOI: 10.1126/sciadv.abb8780

https://phys.org/news/2020-10-photons-quantum.html?utm_source=nwlet...

**Duplications and inversions of DNA segments lead to the masculinization of female moles

Female moles are intersexual while retaining their fertility. Typical for mammals, they are equipped with two X chromosomes, but they simultaneously develop functional ovarian and testicular tissues. In female moles, both tissue types are united in one organ, the ovotestis—a feature unique among mammals.

The testicular tissue of the female mole does not produce sperm, but large amounts of the sex hormone testosterone, meaning the females have similarly high levels as the males. Presumably, this natural "doping" makes the female moles aggressive and muscular, an advantage for life underground, where they have to dig burrows and fight for resources.

Scientists are now reporting on the genetic peculiarities that lead to this characteristic sexual development in moles. According to the study, it is primarily changes in the structure of the genome that lead to altered control of genetic activity. In addition to the genetic program for testicular development, this also stimulates enzymes for male hormone production in the females.

the researchers have completely sequenced the genome of the Iberian mole (Talpa occidentalis) for the first time. Moreover, they examined the three-dimensional structure of the genome within the cell. In the nucleus, genes and their associated control sequences form regulatory domains—relatively isolated "neighborhoods" consisting of large regions where DNA sections interact frequently with each other.

In the course of the moles' evolution, then not only would individual letters of the DNA have changed, also larger pieces of the genome would have shifted.

If segments of DNA move from one location to another, completely new or reorganized regulatory domains can emerge and thus activate new genes and enhance or attenuate their expression.

When comparing the genome to that of other animals and humans, the team discovered an inversion—i.e., an inverted genomic segment—in a region known to be involved in testicular development. The inversion causes additional DNA segments to get included in the regulatory domain of the gene FGF9, which reorganizes the control and regulation of the gene. "This change is associated with the development of testicular tissue in addition to ovarian tissue in female moles.

The team also discovered a triplication of a genomic region responsible for the production of male sex hormones (androgens), more specifically the androgen production gene CYP17A1. "The triplication appends additional regulatory sequences to the gene—which ultimately leads to an increased production of male sex hormones in the ovotestes of female moles, especially more testosterone

 DOI: 10.1126/science.aaz2582 "The mole genome reveals regulatory rearrangements associated with adaptive intersexuality" Science (2020). science.sciencemag.org/cgi/doi … 1126/science.aaz2582

https://phys.org/news/2020-10-duplications-inversions-dna-segments-...

Ants adapt tool use to avoid drowning

Researchers have observed black imported fire ants using sand to draw liquid food out of containers, when faced with the risk of drowning. This is the first time this sophisticated tool use has been reported in animals.

Aiming Zhou et al, Ants adjust their tool use strategy in response to foraging risk, Functional Ecology (2020). DOI: 10.1111/1365-2435.13671

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Nanoscale machines convert light into work

Researchers have developed a tiny new machine that converts laser light into work. These optically powered machines self-assemble and could be used for nanoscale manipulation of tiny cargo for applications such as nanofluidics and particle sorting.

The work addresses a long-standing goal in the nanoscience community to create self-assembling nanoscale machines that can perform work in conventional environments such as room temperature liquids.

The machines are based on a type of matter known as optical matter in which metal nanoparticles are held together by light rather than the chemical bonds that hold together the atoms that make up typical matter.

Both the energy for assembling the machine and the power to make it work come from light. Once the laser light is introduced to a solution containing nanoparticles, the entire process occurs on its own. Although the user does not need to actively control or direct the outcome, this could readily be done to tailor the machines for various applications.

In optical matter, a laser light field creates interactions between metal nanoparticles that are much smaller than the wavelength of light. These interactions cause the particles to self-assemble into ordered arrays. This is a similar principle to optical trapping, in which light is used to hold and manipulate particles, biological molecules and cells.

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In the new work, the researchers created an optical matter machine that operates much like a mechanical machine based on interlocking gears. In such machines, when one gear is turned, a smaller interlocking gear will spin in the opposite direction. The optical matter machine uses circularly polarized light from a laser to create a nanoparticle array that acts like the larger gear by spinning in the optical field. This "optical matter gear" converts the circularly polarized light into orbital, or angular, momentum that influences a nearby probe particle to orbit the nanoparticle array (the gear) in the opposite direction.

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In previous work, the researchers discovered that when optical matter is exposed to circularly polarized light, it rotates as a rigid body in the direction opposite the polarization rotation. In other words, when the incident light  rotates one way the optical matter array responds by spinning the other. This is a manifestation of "negative torque". The researchers speculated that a machine could be developed based on this new phenomenon.

John Parker et al, An Optical Matter Machine: Angular Momentum Conversion by Collective Modes in Optically Bound Nanoparticle Arrays, Optica (2020). DOI: 10.1364/OPTICA.396147

https://phys.org/news/2020-10-nanoscale-machines.html?utm_source=nw...

Human spatial memory prioritizes high calorie foods

Humans more accurately recall the locations of high calorie than low calorie foods, according to a study . The findings suggest that human spatial memory, which allows people to remember where objects are in relation to each another, has evolved to prioritize the location of high calorie foods.

The findings indicate that human spatial memory is biased towards locating high calorie foods. This bias could have helped human ancestors to survive in environments with fluctuating food availability by enabling them to efficiently locate calorie-dense foods through foraging.

Human spatial memory implicitly prioritizes high-calorie foods, Scientific Reports (2020). DOI: 10.1038/s41598-020-72570-x , www.nature.com/articles/s41598-020-72570-x

https://medicalxpress.com/news/2020-10-human-spatial-memory-priorit...

**New model may explain rarity of certain malaria-blocking mutations

A new computational model suggests that certain mutations that block infection by the most dangerous species of malaria have not become widespread in people because of the parasite's effects on the immune system.

Several protective adaptations to malaria have spread widely among humans, such as the sickle-cell mutation. Laboratory experiments suggest that certain other mutations could be highly protective against the most dangerous human-infecting malaria species, Plasmodium falciparum. However, despite being otherwise benign, these mutations have not become widespread.

To help clarify why some protective mutations may remain rare, Penman and colleagues developed a computational model that simulates the epidemiology of malaria infection, as well the evolution of protective mutations. Importantly, the model also incorporates mechanisms of adaptive immunity, in which the immune system "learns" to recognize and attack specific pathogens, such as P. falciparum.

Analysis of the model's predictions suggests that if people rapidly gain adaptive immunity to the severe effects of P. falciparum malaria, mutations capable of blocking P. falciparum infection are unlikely to spread among the population. The fewer the number of infections it takes for people to become immune to the severe effects of malaria, the less likely it is that malaria infection-blocking mutaions will arise.

understanding how humans have adapted to malaria could help open up new avenues for treatment.

 Penman BS, Gandon S (2020) Adaptive immunity selects against malaria infection blocking mutations. PLoS Comput Biol 16(10): e1008181. doi.org/10.1371/journal.pcbi.1008181

https://phys.org/news/2020-10-rarity-malaria-blocking-mutations.htm...

Thinning forests no defence against fires

Having logging machines "thin" forest for fire reduction is largely ineffective, a new peer-reviewed, scientific study has found.

The study compared fire severity in unthinned versus thinned forest burned in the 2009 wildfires. It covered two forest types-mixed species forest and ash forest.

The scientific evidence showed that across almost every forest age and type, thinning made little difference. It actually increased the likelihood of a crown burn in older, mixed species forests, and slightly reduced the chance of crown burn in younger aged, mixed species forest.

The impact of thinning varied with forest type, the age of the forest and fire conditions.

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Across most forest types and ages, thinning had little impact on forest fire severity, although it did worsen severity in mixed species forest aged 70 years plus and did reduce it in mixed species forest aged 20-40 years. Overall, the evidence indicates thinning forests does not reduce fire risk.

Chris Taylor et al. Does forest thinning reduce fire severity in Australian eucalypt forests?, Conservation Letters (2020). DOI: 10.1111/conl.12766

https://phys.org/news/2020-10-thinning-forests-defence.html?utm_sou...

Signals from distant stars connect optical atomic clocks across Earth for the first time

Using radio telescopes observing distant stars, scientists have connected optical atomic clocks on different continents.

 Marco Pizzocaro et al, Intercontinental comparison of optical atomic clocks through very long baseline interferometry, Nature Physics (2020). DOI: 10.1038/s41567-020-01038-6

In this new research, highly-energetic extragalactic radio sources replace satellites as the source of reference signals. The group of Sekido Mamoru at NICT designed two special radio telescopes, one deployed in Japan and the other in Italy, to realize the connection using the technique of Very Long Baseline Interferometry (VLBI). These telescopes are capable of observations over a large bandwidth, while antenna dishes of just 2.4 meter diameter keep them transportable.

https://phys.org/news/2020-10-distant-stars-optical-atomic-clocks.h...

Stomach Acid & Heartburn Drugs Linked with COVID-19 Outcomes

Millimetre-precision drug delivery to the brain

Researchers  have developed a method for concentrating and releasing drugs in the brain with pinpoint accuracy. This could make it possible in the future to deliver psychiatric and cancer drugs and other medications only to those regions of the brain where this is medically desirable.

In order to prevent a drug from acting on the entire brain and body, the new method involves special drug carriers that wrap the drugs in spherical lipid vesicles attached to gas-​containing ultrasound-​sensitive microbubbles. These are injected into the bloodstream, which transports them to the brain. Next, the scientists use focused ultrasound waves in a two-​stage process. Focused ultrasound is already employed in oncology to destroy cancer tissue at precisely defined points in the body. In the new invention, however, the scientists work with much lower energy levels, which do not damage the tissue.

Ozdas MS, Shah AS, Johnson PM, Patel N, Marks M, Yasar TB, Stalder U, Bigler L, von der Behrens W, Sirsi SR, Yanik MF: Non-​invasive molecularly-​specific millimeterresolution manipulation of brain circuits by ultrasound-​mediated aggregation and uncaging of drug carriers. Nature Communications, 1 October 2020, doi: 10.1038/s41467-​020-18059-7

https://ethz.ch/en/news-and-events/eth-news/news/2020/10/millimetre...

https://researchnews.cc/news/2923/Millimetre-precision-drug-deliver...

This ‘squidbot’ jets around and takes pics of coral and fish

More Humans Are Growing an Extra Artery in Our Arms, Showing We're Still Evolving

Researchers have noticed an artery that temporarily runs down the centre of our forearms while we're still in the womb isn't vanishing as often as it used to.

That means there are more adults than ever running around with what amounts to be an extra channel of vascular tissue flowing under their wrist.

Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it's clearly increasing.

The prevalence was around 10 percent in people born in the mid-1880s compared to 30 percent in those born in the late 20th century, so that's a significant increase in a fairly short period of time, when it comes to evolution.

Recently increased prevalence of the human median artery of the forearm: A microevolutionary change

The median artery has been considered as an embryonic structure, which normally regresses around the 8th week of gestation. However, various prevalences have been reported in adults since the 18th century. Furthermore, in a study by Henneberg and George (1995; Am J Phys Anthropol 96, 329–334), has suggested that increasing prevalence of the median artery during the 20th century was a ‘possible secular trend’. The present study, conducted nearly a quarter of a century later, is a continuation of that study. A total of 26 median arteries were found in 78 upper limbs obtained from Australians aged 51 to 101 years, who died in the period 2015–2016, a prevalence rate of 33.3%. Analysis of the literature showed that the presence of the median artery has been significantly increasing (p = .001) over time, from approximately 10% in people born in the mid‐1880s to approximately 30% by the end of the 20th century. The significance of the prevalence increased to a p value

https://onlinelibrary.wiley.com/doi/epdf/10.1111/joa.13224

A bird is male on one side and female on the other

Male rose-breasted grosbeaks have some red-pink feathers while females’ are yellow and brown

A rose-breasted grosbeak has a pink breast spot and a pink “wing pit” and black feathers on its right wing — tell tale shades of males. But on its left side, the songbird displays yellow and brown plumage, hues typical of females.

Gynandromorphs are found in many species of birds, insects and crustaceans such as crabs and lobsters. This bird is likely the result of an unusual event when two sperm fertilize an egg that has two nuclei instead of one. The egg can then develop male sex chromosomes on one side and female sex chromosomes on the other, ultimately leading to a bird with a testis and other male characteristics on one half of its body and an ovary and other female qualities on the other half.

Unlike hermaphrodites, which also have genitals of both sexes, gynandromorphs are completely male on one side of the body and female on the other.

We don’t yet know if these birds behave more like males or females, or if they can reproduce

R.J. Agate et al. Neural, not gonadal, origin of brain sex differences in a gynandrom.... Proceedings of the National Academy of Sciences. Vol. 100, April 15, 2003, p. 4873. doi: 10.1073/pnas.0636925100.

Some Fish Can Regenerate Their Eyes. Know what? Mammals Have Those Genes Too to do that.

But, they are switched off! Scientists want to switch them on again.

Damage to the retina is the leading cause of blindness in humans, affecting millions of people around the world. Unfortunately, the retina is one of the few tissues we humans can't grow back. Unlike us, other animals such as zebrafish are able to regenerate this tissue that's so crucial to our power of sight. We share 70% of our genes with these tiny little zebrafish, and scientists have just discovered some of the shared genes include the ones that grant zebrafish the ability to grow back their retinas.

The genes activated were involved in containing the injury, calling in immune cells to clean up damaged tissue and fight off potential invaders.

But then, a network that suppresses these genes kicked in only in their mouse subjects, keeping them from transforming into cells that produce other kinds of retinal cells. Researchers suspect that the loss of this ability may be linked to a trade-off between regenerating central nervous system cells and parasite resistance. Glia help restrict the spread of infections, and if they're turned into neuron-producing cells, they can't do this.

The researchers also noticed that after a retinal injury glial cells in all three species stopped making nuclear factor I (NFI), a protein that stops the cell from accessing bits of DNA, essentially turning genes off.

But in mice, this molecule started appearing again fairly soon. So, the team stopped Müller glia cells producing NFI and the cells started making retinal neurons in adult mice after injury.

This is a highly complicated system with many independent mechanisms involved that need to be further explored. But understanding these pathways may one day allow scientists to help us better repair damaged sight.

Gene regulatory networks controlling vertebrate retinal regeneration