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Comment by Dr. Krishna Kumari Challa 6 hours ago

Nearly 5 mn fewer girls to be born worldwide over next 10 years: study

An estimated 4.7 million fewer girls are expected to be born globally in the next 10 years because of sex-selective practices in countries with a cultural preference for male offspring, a trend that could undermine social cohesion in the long term, research showed on Tuesday. The research suggested that the projected shortfall in the number of girls being born will lead to a surplus of young men in around a third of the global population by 2030, which could lead to increased anti-social behaviour and violence. Sex-selective abortions have been on the rise for the past 40 years in countries throughout southeast Europe along with south and east Asia, with as-yet undetermined demographic impacts. To model what short- and long-term effect sex selection will have on societies, an international team of researchers analysed data from more than three billion births over the last 50 years. Focusing on 12 countries where the male-to-female ratio had increased since 1970 and another 17 where that ratio was at risk of increasing due to social or cultural trends, they simulated two scenarios.

The first assumed an increase in the rate of sex selection, based on statistical evidence.

The second scenario assumed increased sex selection in certain countries, based on observed trends and decreased fertility, but for which specific data were lacking.

In scenario 1, countries saw a shortfall of 4.7 million in the number of girls being born by 2030. For scenario 2, the figure jumped to more than 22 million globally by 2100.

Authors of the research, published in the BMJ medical journal, said the bias towards male offspring could lead to a "marriage squeeze" in affected countries.

"Fewer-than-expected females in a population could result in elevated levels of anti-social behaviour and violence, and may ultimately affect long-term stability and social sustainable development," they wrote.

The United Nations defines sex-selective practices alongside child marriage and female genital mutilation as harmful practices targeted under the Millennium Development Goals.

The authors of the new study called for better data collection of such practices in order to stamp them out, as well as wider education initiatives.

"A broader objective relates to the need to influence gender norms which lie at the core of harmful practices such as prenatal sex selection," they wrote.

"This calls for broader legal frameworks to ensure gender equality."

Source:  Agence France-Presse

Comment by Dr. Krishna Kumari Challa 6 hours ago

Together, the energy reaching Earth's surface from the sun and from the atmosphere is about 504 watts per square meter. Earth's surface emits about 79% of that back out. The remaining surface energy goes into evaporating water and warming the air, oceans and land.

The tiny residual between incoming sunshine and outgoing infrared is due to the accumulation of greenhouse gases like carbon dioxide in the air. These gases are transparent to sunlight but opaque to infrared rays—they absorb and emit a lot of infrared rays back down.

Earth's surface temperature must increase in response until the balance between incoming and outgoing radiation is restored.

Doubling of carbon dioxide would add 3.7 watts of heat to every square meter of the Earth. Imagine old-fashioned incandescent night lights spaced every 3 feet over the entire world, left on forever.

At the current rate of emissions, greenhouse gas levels would double from preindustrial levels by the middle of the century.

Climate scientists calculate that adding this much heat to the world would warm Earth's climate by about 5 degrees Fahrenheit (3 C). Preventing this would require replacing fossil fuel combustion, the leading source of greenhouse gas emissions, with other forms of energy.

https://theconversation.com/earths-energy-budget-is-out-of-balance-...

part 4

Comment by Dr. Krishna Kumari Challa 6 hours ago

Earth's Delicate Energy Balance

Comment by Dr. Krishna Kumari Challa 6 hours ago

Virtually all the energy in the Earth's climate system comes from the sun. Only a tiny fraction is conducted upward from the Earth's interior.

On average, the planet receives 340.4 watts of sunshine per square meter. All sunshine falls on the daytime side, and the numbers are much higher at local noon.

Of that 340.4 watts per square meter:
99.9 watts are reflected back into space by clouds, dust, snow and the Earth's surface.
The remaining 240.5 watts are absorbed—about a quarter by the atmosphere and the rest by the surface of the planet. This radiation is transformed into thermal energy within the Earth system. Almost all of this absorbed energy is matched by energy emitted back into space. A tiny residual—0.6 watts per square meter—accumulates as global warming. That may not sound like much, but it adds up.
The atmosphere absorbs a lot of energy and emits it as radiation both into space and back down to the planet's surface. In fact, Earth's surface gets almost twice as much radiation from the atmosphere as it does from direct sunshine. That's primarily because the sun heats the surface only during the day, while the warm atmosphere is up there 24/7.

part 2

Comment by Dr. Krishna Kumari Challa 6 hours ago

Earth's energy budget is out of balance – here's how it's warming the climate

Energy can neither be created nor destroyed. That's a fundamental property of the universe.

Energy can be transformed, however. When the sun's rays reach Earth, they are transformed into random motions of molecules that you feel as heat. At the same time, Earth and the atmosphere are sending radiation back into space. The balance between the incoming and outgoing energy is known as Earth's "energy budget."

Our climate is determined by these energy flows. When the amount of energy coming in is more than the energy going out, the planet warms up.

That can happen in a few ways, such as when sea ice that normally reflects solar radiation back into space disappears and the dark ocean absorbs that energy instead. It also happens when greenhouse gases build up in the atmosphere and trap some of the energy that otherwise would have radiated away.

part 1

Comment by Dr. Krishna Kumari Challa 6 hours ago

Study reveals how smell receptors work

All senses must reckon with the richness of the world, but nothing matches the challenge faced by the olfactory system that underlies our sense of smell. We need only three receptors in our eyes to sense all the colors of the rainbow—that's because different hues emerge as light-waves that vary across just one dimension, their frequency. The vibrant colorful world, however, pales in comparison to the complexity of the chemical world, with its many millions of odors, each composed of hundreds of molecules, all varying greatly in shape, size and properties. The smell of coffee, for instance, emerges from a combination of more than 200 chemical components, each of which are structurally diverse, and none of which actually smells like coffee on its own.

To form a basic understanding of odorant recognition we need to know how a single receptor can recognize multiple different chemicals, which is a key feature of how the olfactory system works 

The olfactory system has to recognize a vast number of molecules with only a few hundred odour receptors or even less. It's clear that it had to evolve a different kind of logic than other sensory systems.

In a new study researchers offer answers to the decades-old question of odour recognition by providing the first-ever molecular views of an olfactory receptor at work.

The findings, published in Nature, reveal that olfactory receptors indeed follow a logic rarely seen in other receptors of the nervous system. While most receptors are precisely shaped to pair with only a few select molecules in a lock-and-key fashion, most olfactory receptors each bind to a large number of different molecules. Their promiscuity in pairing with a variety of odors allows each receptor to respond to many chemical components. From there, the brain can figure out the odor by considering the activation pattern of combinations of receptors.

 The structural basis of odorant recognition in insect olfactory receptors, Nature (2021). DOI: 10.1038/s41586-021-03794-8 , www.nature.com/articles/s41586-021-03794-8

https://phys.org/news/2021-08-reveals-receptors.html?utm_source=nwl...

Comment by Dr. Krishna Kumari Challa 8 hours ago

Driverless Tractor: India’s Innovation

Comment by Dr. Krishna Kumari Challa yesterday

Cryptic transcription in mammalian stem cells linked to aging

Although visible signs of aging are usually unmistakable, unraveling what triggers them has been quite a challenge. Researchers have discovered that a cellular phenomenon called cryptic transcription, which had been previously described and linked to aging in yeasts and worms, is elevated in aging mammalian stem cells.

Researchers report in the journal Nature Aging that cryptic transcription occurs because a cellular mechanism that keeps it in check falls apart as cells get old. The findings suggest that strategies that control cryptic transcription could have pro-longevity effects.

In previous work, they showed that cryptic transcription in yeasts and worms is not only a marker of aging but also a cause. Reducing the amount of this aberrant transcription in these organisms prolonged their lifespan.

Cryptic transcription is a phenomenon that interferes with normal cellular processes. Normal gene transcription is a first step in the production of proteins. It begins in a specific location on the DNA called the promoter. This is where the protein coding gene begins to be transcribed into RNA, which is eventually translated into protein. Gene transcription is a well-regulated cellular process, but as cells age, they lose their ability to control it.

Promoters have a specific DNA sequence that identifies the starting point of the transcription process that is usually located preceding the actual protein coding sequence.

But promoter look-alike sequences do exist in other locations, including along the actual protein coding sequence, and they could start transcription and generate shorter transcripts, called cryptic transcripts.

worked with mammalian stem cells, which have shown to play a significant role in aging. They adapted a method to detect cryptic transcription to determine the level of this transcription in mice and human stem cells and cultured cells. When compared to young stem cells, older ones had increased cryptic transcription. They also looked into other aging cells and found that, in the majority of cells spanning a range of tissues, cryptic transcription was also elevated with age.

Altogether, these findings indicate that elevated cryptic transcription is a hallmark of mammalian aging. Young cells have mechanisms in place to prevent cryptic transcription. In aged mammalian cells, the researchers found that one such mechanisms, which involves limiting the access to chromatin, the material that makes up the chromosomes, is failing, facilitating the production of cryptic transcripts.

https://www.nature.com/articles/s43587-021-00091-x

https://researchnews.cc/news/8148/Cryptic-transcription-in-mammalia...

Comment by Dr. Krishna Kumari Challa yesterday

Particles from paints, pesticides can have deadly impact

Hundreds of thousands of people around the world die too soon every year because of exposure to air pollution caused by our daily use of chemical products and fuels, including paints, pesticides, charcoal and gases from vehicle tailpipes, according to a new study.

Researchers calculated that air pollution caused by "anthropogenic secondary organic aerosol" causes 340,000-900,000 premature deaths. Those are tiny particles in the atmosphere that form from chemicals emitted by human activities.

The older idea was that to reduce premature mortality, you should target coal-fired power plants or the transportation sector. Yes, these are important, but this study is showing that if you're not getting at the cleaning and painting products and other everyday chemicals, then you're not getting at a major source.

Atmospheric researchers have long understood that particles in the atmosphere small enough to be inhaled can damage people's lungs and increase mortality. Studies have estimated that fine particle pollution, often called PM2.5, leads to 3-4 million premature deaths  globally per year, possibly more.

The new work suggests that a third broad category of chemicals—anthropogenic secondary organic pollutants—is a significant indirect source of deadly fine particles.

Benjamin A. Nault et al, Secondary organic aerosols from anthropogenic volatile organic compounds contribute substantially to air pollution mortality, Atmospheric Chemistry and Physics (2021). DOI: 10.5194/acp-21-11201-2021

https://phys.org/news/2021-08-particles-pesticides-deadly-impact.ht...

Comment by Dr. Krishna Kumari Challa yesterday

How sex cells get the right genetic mix

A new discovery explains what determines the number and position of genetic exchanges that occur in sex cells, such as pollen and eggs in plants, or sperm and eggs in humans.

When sex cells are produced by a special cell division called meiosis, chromosomes exchange large segments of DNA. This ensures that each new cell has a unique genetic makeup and explains why, with the exception of identical twins, no two siblings are ever completely genetically alike. These exchanges of DNA, or crossovers, are essential for generating genetic diversity, the driving force for evolution, and their frequency and position along chromosomes are tightly controlled.

Crossover positioning has important implications for evolution, fertility and selective breeding. By understanding the mechanisms that drive crossover positioning we are more likely to be able to uncover methods to modify crossover positioning to improve current plant and animal breeding technologies.

A research team studied the behavior of a protein called HEI10 which plays an integral role in crossover formation in meiosis. Super-resolution microscopy revealed that HEI10 proteins cluster along chromosomes, initially forming lots of small groups. However, as time passes, the HEI10 proteins concentrate in only a small number of much larger clusters which, once they reach a critical mass, can trigger crossover formation.

These measurements were then compared against a mathematical model which simulates this clustering, based on diffusion of the HEI10 molecules and simple rules for their clustering. The mathematical model was capable of explaining and predicting many experimental observations, including that crossover frequency could be reliably modified by simply altering the amount HEI10.

This study shows that data from super-resolution images of Arabidopsis reproductive cells is consistent with a mathematical 'diffusion-mediated coarsening' model for crossover patterning in Arabidopsis. The model helps us understand the patterning of crossovers along meiotic chromosomes.

Diffusion-mediated HEI10 coarsening can explain meiotic crossover positioning in Arabidopsis" appears in Nature Communications.

Diffusion-mediated HEI10 coarsening can explain meiotic crossover positioning in Arabidopsis, Nature Communications (2021). DOI: 10.1038/s41467-021-24827-w

https://phys.org/news/2021-08-sex-cells-genetic-interdisciplinary-a...

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