Comment

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:24am

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?...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:14am

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...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 8:04am

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...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 6:23am

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'. 

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 6:15am

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...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 6:06am

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

Scientists can generate squeezed light via strongly driven spontaneous four-wave mixing below threshold in silicon nitride microring resonators. The generated light can be characterized with homodyne detection (to extract phase- or frequency-encoded information) and through direct measurements of photon statistics.

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...

Comment by Dr. Krishna Kumari Challa on October 6, 2020 at 5:58am

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...

Comment by Dr. Krishna Kumari Challa on October 5, 2020 at 10:12am

A new thermometer measures temperature with sound

An acoustic thermometer takes temperature by listening to the faint hum that objects give off when they get hot.

Hot objects not only glow, but also softly hum. The hum is generated by the rapid jitters of particles that make up the hot object. If human ears were keen enough to hear this noise, “it would sound like radio static”.  The hotter [an object] gets, the louder it gets. So scientists created an acoustic thermometer that senses the intensity of heat-generated sound emanating from nearby objects.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.120603

https://www.sciencenews.org/article/new-thermometer-measures-temper...

Comment by Dr. Krishna Kumari Challa on October 5, 2020 at 9:08am

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

These people have abilities far beyond what the average person might be able to do, including seeing underwater, resisting the cold and tolerating pain.

https://www.sciencefocus.com/the-human-body/meet-the-real-life-supe...

Comment by Dr. Krishna Kumari Challa on October 4, 2020 at 9:41am

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

• ‹ Previous
• 1
• …
• 750
• 751
• 752
• 753
• 754
• …
• 1085
• Next ›
• Page