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Comment by Dr. Krishna Kumari Challa on December 17, 2020 at 9:32am

Where does the Earth's heat come from?

Earth generates heat. The deeper you go, the higher the temperature. At 25km down, temperatures rise as high as 750°C; at the core, it is said to be 4,000°C. Humans have been making use of hot springs as far back as antiquity, and today we use geothermal technology to heat our apartments. Volcanic eruptions, geysers and earthquakes are all signs of the Earth's internal powerhouse.

The average heat flow from the earth's surface is 87mW/m² – that is, 1/10,000th of the energy received from the sun, meaning the earth emits a total of 47 terawatts, the equivalent of several thousand nuclear power plants. The source of the earth's heat has long remained a mystery, but we now know that most of it is the result of radioactivity.

The birth of atoms

To understand where all this heat is coming from, we have to go back to the birth of the atomic elements.

The Big Bang produced matter in the form of protons, neutrons, electrons, and neutrinos. It took around 370,000 years for the first atoms to form—protons attracted electrons, producing hydrogen. Other, heavier nuclei, like deuterium and helium, formed at the same time, in a process called Big Bang nucleosynthesis.

The creation of heavy elements was far more arduous. First, stars were born and heavy nuclei formed via accretion in their fiery crucible. This process, called stellar nucleosynthesis, took billions of years. Then, when the stars died, these elements spread out across space to be captured in the form of planets.

The earth's composition is therefore highly complex. Luckily for us, and our existence, it includes all the natural elements, from the simplest atom, hydrogen, to heavy atoms such as uranium, and everything in between, carbon, iron—the entire periodic table. Inside the bowels of the earth is an entire panoply of elements, arranged within various onion-like layers.

We know little about the inside of our planet. The deepest mines reach down 10km at the most, while the earth has a radius of 6,500km. Scientific knowledge of deeper levels has been obtained through seismic measurements. Using this data, geologist divided the earth's structure into various strata, with the core at the center, solid on the inside and liquid on the outside, followed by the lower and upper mantles and, finally, the crust. The earth is made up of heavy, unstable elements and is therefore radioactive, meaning there is another way to find out about its depths and understand the source of its heat.

Radioactivity is a common and inescapable natural phenomenon. Everything on earth is radioactive—that is to say, everything spontaneously produces elementary aprticles (humans emit a few thousand per second).

There are various kinds of radioactivity, each involving the spontaneous release of particles and emitting energy that can be detected in the form of heat deposits. Here, we will be talking about "beta" decay, where an election and a neutrino are emitted. The electron is absorbed as soon as it is produced, but the neutrino has the surprising ability to penetrate a wide range of materials. The whole of the Earth is transparent to neutrinos, so detecting neutrinos generated by radioactive decay within the Earth should give us an idea of what is happening at its deepest levels.

These kinds of particles are called geonutrinos, and they provide an original way to investigate the depths of the Earth. Although detecting them is no easy matter, since neutrinos interact little with matter, some detectors are substantial enough to perform this kind of research.

https://theconversation.com/where-does-the-earths-heat-come-from-15...

Comment by Dr. Krishna Kumari Challa on December 17, 2020 at 8:30am

New type of atomic clock could help scientists detect dark matter and study gravity's effect on time

Atomic clocks are the most precise timekeepers in the world. These exquisite instruments use lasers to measure the vibrations of atoms, which oscillate at a constant frequency, like many microscopic pendulums swinging in sync. The best atomic clocks in the world keep time with such precision that, if they had been running since the beginning of the universe, they would only be off by about half a second today.

Still, they could be even more precise. If atomic clocks could more accurately measure atomic vibrations, they would be sensitive enough to detect phenomena such as dark matter and gravitational waves. With better atomic clocks, scientists could also start to answer some mind-bending questions, such as what effect gravity might have on the passage of time and whether time itself changes as the universe ages.

Now a new kind of atomic clock designed by MIT physicists may enable scientists explore such questions and possibly reveal new physics.

The researchers report in the journal Nature that they have built an atomic clock that measures not a cloud of randomly oscillating atoms, as state-of-the-art designs measure now, but instead atoms that have been quantumly entangled. The atoms are correlated in a way that is impossible according to the laws of classical physics, and that allows the scientists to measure the atoms' vibrations more accurately.

The new setup can achieve the same precision four times faster than clocks without entanglement.

Entanglement on an optical atomic-clock transition, Nature (2020). DOI: 10.1038/s41586-020-3006-1 , www.nature.com/articles/s41586-020-3006-1

https://phys.org/news/2020-12-atomic-clock-precisely.html?utm_sourc...

Comment by Dr. Krishna Kumari Challa on December 17, 2020 at 7:19am

Quantum insulators create multilane highways for electrons

New energy-efficient electronic devices may be possible thanks to research that demonstrates the quantum anomalous Hall (QAH) effect—where an electrical current does not lose energy as it flows along the edges of the material—over a broader range of conditions. A team of researchers from Penn State has experimentally realized the QAH effect in a multilayered insulator, essentially producing a multilane highway for the transport of electrons that could increase the speed and efficiency of information transfer without energy loss.

Tuning the Chern number in quantum anomalous Hall insulators, Nature (2020). DOI: 10.1038/s41586-020-3020-3 , www.nature.com/articles/s41586-020-3020-3

https://phys.org/news/2020-12-quantum-insulators-multilane-highways...

Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 10:22am

Giant Viruses Can Integrate into the Genomes of Their Hosts

Rather than introducing small chunks of DNA as other viruses do, some giant viruses can contribute more than 1 million base pairs to a host’s genome, broadening the ways in which viruses may shape eukaryote evolution.

https://www.nature.com/articles/s41586-020-2924-2.epdf?sharing_toke...

https://www.the-scientist.com/news-opinion/giant-viruses-can-integr...

Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 9:47am

Shedding light on the dark side of biomass burning pollution

Oxidized organic aerosol is a major component of ambient particulate matter, substantially impacting climate, human health and ecosystems. Oxidized aerosol from biomass burning is especially toxic, known to contain a large amount of mutagens that are known carcinogens. Inhaling biomass burning particles can also cause oxidative stress and a wide range of diseases such as heart attacks, strokes and asthma. Oxidized aerosol primarily forms from the atmospheric oxidation of volatile and semi-volatile compounds emitted by sources like biomass burning, resulting in products that readily form particulate matter. Every model in use today assumes that oxidized aerosol forms in the presence of sunlight, and that it requires days of atmospheric processing to reach the levels observed in the environment. Naturally, this implies that oxidized aerosol forms in the daytime and mostly during periods with plentiful sunshine, such as in summer.

However, considerable amounts of oxidized organic aerosol forms during the winter and in other periods of low photochemical activity worldwide, often during periods of intense biomass burning. Models underestimate oxidized aerosol levels by a factor of three to five. This unresolved mystery carries significant implications for public health and climate, given that biomass burning events are often associated with population exposure to very high particulate matter levels. This issue will become more important in the future, given the increase intensity, duration and frequency of wood burning (both domestic and wildfire) around the globe.

John K. Kodros el al., "Rapid dark aging of biomass burning as an overlooked source of oxidized organic aerosol," PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2010365117

https://phys.org/news/2020-12-dark-side-biomass-pollution.html?utm_...

Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 9:39am

Reducing pesticide use with nanoparticles

Researchers  have discovered how certain silica nanoparticles could act as a traceless, degradable, and highly efficient treatment against some plant pathogens.

 With an increasing number of products banned or considered dangerous for human and animal health, the need for substitutes is acute. One approach is to stimulate plants' own immune response to pathogen attacks. Silicic acid, which naturally occurs in soil, is known to provoke such responses in plants, and amorphous silica nano-particles can release this substance in small amounts. These nanoparticles, which are also naturally present in many food crops such as cereals, are more common than most people think. They are part of food grade silica (SiO2), otherwise known as E551 on labels and packaging, and used for decades in a variety of products such as table salt, pills, or protein powders to avoid clumping.

With this in mind, the researchers aimed to create an environmentally safe nano-agrochemical for the targeted delivery of silicic acid and to stimulate plant defense. They synthesized silica nanoparticles with similar properties to those found in plants. To test their efficiency, they applied the nanoparticles on Arabidopsis thaliana (thale cress), a widely used plant model, infected with the bacterial pest Pseudomonas syringae, another model organism. The results showed that their nanoparticles can boost resistance against the bacteria in a dose-dependent manner by stimulating the plant's defense hormone, salicylic acid (which is also the active ingredient in aspirin). The researchers also investigated the interactions of the nanoparticles with plant leaves. They were able to show that nanoparticle uptake and action occurred exclusively through the leaf pores (stomata) that allow the plants to breathe.

Mohamed El-Shetehy et al. Silica nanoparticles enhance disease resistance in Arabidopsis plants, Nature Nanotechnology (2020). DOI: 10.1038/s41565-020-00812-0

https://phys.org/news/2020-12-pesticide-nanoparticles.html?utm_sour...

Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 9:34am

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Apathy could predict onset of dementia years before other symptoms

Apathy—a lack of interest or motivation—could predict the onset of some forms of dementia many years before symptoms start, offering a 'window of opportunity' to treat the disease at an early stage, according to new research from a team of scientists.

Frontotemporal dementia is a significant cause of dementia among younger people. It is often diagnosed between the ages of 45 and 65. It changes behaviour, language and personality, leading to impulsivity, socially inappropriate behaviour, and repetitive or compulsive behaviours.

A common feature of frontotemporal dementia is apathy, with a loss of motivation, initiative and interest in things. It is not depression, or laziness, but it can be mistaken for them. Brain scanning studies have shown that in people with frontotemporal dementia it is caused by shrinkage in special parts at the front of the brain—and the more severe the shrinkage, the worse the apathy. But, apathy can begin decades before other symptoms, and be a sign of problems to come.

Malpetti, M et al. Apathy in pre-symptomatic genetic frontotemporal dementia predicts cognitive decline and is driven by structural brain changes. Alzheimer's & Dementia; 14 Dec 2020; DOI: 10.1002/alz.12252

https://medicalxpress.com/news/2020-12-apathy-onset-dementia-years-...

Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 9:10am

Chameleon-like material spiked with boron comes closer to mimicking brain cells

Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 8:57am

Embryonic development in a Petri dish

 It would certainly spare mothers the hardships of pregnancy, but mammals do not grow in eggs. In a way, this is also impractical for science. While embryos of fish, amphibians or birds can be easily watched growing, mammalian development evades the gaze of the observer as soon as the embryo implants into the uterus. This is precisely the time when the embryo undergoes profound changes in shape and develops precursors of various organs  a highly complex process that leaves many questions unanswered. But now a research team  succeeded in replicating a central phase of embryonic development in a cell culture approach by growing the core portion of the trunk from mouse embryonic stem cells for the first time. The method recapitulates the early shape-generating processes of embryonic development in the Petri dish. 

A gel provides support and spatial orientation
So far, it has only been possible to grow cell clusters from embryonic stem cells, so-called gastruloids. “Cellular assemblies in gastruloids develop to a similar extent like in our trunk-like structures, but they do not assume the typical appearance of an embryo” says Jesse Veenvliet, one of the two lead authors of the study. “The cell clusters lack the signals that trigger their organization into a meaningful arrangement.”

In the cell culture, the required signal is generated by a special gel that mimics the properties of the extracellular matrix. This jelly-like substance consists of a complex mixture of extended protein molecules that is secreted by cells and is found throughout the body as an elastic filling material, especially in connective tissues. The utilization of this gel is the crucial “trick” of the new method.
Cells with similar properties as in the embryo
After four to five-days, the team dissolved the structures into single cells and analyzed them individually. “Even though not all cell types are present in the trunk-like structures, they are strikingly similar to an embryo of the same age.

https://researchnews.cc/news/4117/Embryonic-development-in-a-Petri-...

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Comment by Dr. Krishna Kumari Challa on December 16, 2020 at 8:51am

The bats that wear face masks!

The wrinkle-faced bat covers its face with a flap of skin, seemingly as part of its courtship rituals.

https://www.scientificamerican.com/podcast/episode/this-bat-wears-a...

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