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Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 9:20am

It's not as difficult as you think to shout upwind, shows study

For years, people have been wondering why it feels so difficult to shout upwind. The sensation is common enough to have found its way into an idiom about not being understood. But a scientific explanation for the phenomenon is  - there wasn't been one!

A research team showed that our common sense understanding of this situation is wrong. It isn't harder to shout into the wind; it's just harder to hear yourself.

In fact, acousticians have long known that sound carries better within the first 100 meters upwind. Many people have noticed that a siren sounds louder as it approaches and then quieter as it moves away. The mechanics behind this is similar to the Doppler effect, in which a sound changes frequency as it moves.

Research had confirmed that wind doesn't affect the emanation pattern of speech, so there was no reason why shouting into the wind would be difficult.

Their results were surprising but simple: it's harder for people to hear themselves when shouting upwind.

When someone shouts upwind, their ears are situated downwind from their mouth, which means that their ears receive less sound—it's harder from them to hear their shout than when there's no wind.

The same thing happens when someone is moving quickly even if there's no wind blowing—if you're cycling, for example. As a person bikes, their motion generates a wind around their head even in stationary air, and they end up shouting because they can't hear their own voice well.

So be careful what you shout upwind, for others might hear you just fine, even if you don't. This information is particularly useful for people who work with sound, such as musicians.

Ville Pulkki et al, Perceived difficulty of upwind shouting is a misconception explained by convective attenuation effect, Scientific Reports (2023). DOI: 10.1038/s41598-023-32306-z

Comment by Dr. Krishna Kumari Challa on April 24, 2023 at 10:29am

eHighway - solution for electrified road freight transport

Comment by Dr. Krishna Kumari Challa on April 23, 2023 at 11:21am

Stuck stem cells cause grey hair

Hair turns grey when melanocyte stem cells in the hair follicle fail to mature into thei... — at least that’s true in mice, and humans have similar cells. Scientists had thought that hair greys because the follicle runs out of melanocytes. A team tracked individual cells in mice over two years, which revealed that melanocytes travel up and down the hair follicle and switch back and forth between mature and young states. When the cells become stuck and stop making this journey, they stop receiving the signal to produce pigment.

Unlike embryonic stem cells, which develop into all sorts of different organs, adult stem cells have a more set path. The melanocyte stem cells in our hair follicles are responsible for producing and maintaining the pigment in our hair.

Each hair follicle keeps immature melanocyte stem cells in storage. When they’re needed, those cells travel from one part of the follicle to another, where proteins spur them to mature into pigment-producing cells, giving hair its hue.

Scientists assumed that gray hair was the result of that pool of melanocyte stem cells running dry. However, previous studies with mice made  scientists wonder if hair could lose its pigment even when stem cells are still present.

To learn more about stem cell behavior throughout different phases of hair growth, the researchers spent two years tracking and imaging individual cells in mouse fur. To their amazement, the stem cells traveled back and forth within the hair follicle, transitioning into their mature, pigment-producing state and then out of it again.

But as time wore on, the melanocyte cells couldn’t keep up the double act. A hair falling out and growing back takes a toll on the follicle, and eventually, the stem cells stopped making their journey, and thus, stopped receiving protein signals to make pigment. From then on, the new hair growth didn’t get its dose of melanin.

The researchers further explored this effect by plucking hairs from mice, simulating a faster hair growth cycle. This “forced aging” led to a buildup of melanocyte stem cells stuck in their storage place, no longer producing melanin. The mice’s fur went from dark brown to salt-and-pepper.

While the study was conducted with rodents, the researchers say their findings should be relevant to how human hair gets and loses its color. What’s more, they hope their findings could be a step toward preventing or reversing the graying process.

https://www.nature.com/articles/s41586-023-05960-6.epdf?sharing_tok...

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 12:43pm

Dendrites are the traffic lights of our nervous system. If an action potential is significant enough, it can be passed on to other nerves, which can block or pass on the message.

This is the logical underpinnings of our brain – ripples of voltage that can be communicated collectively in two forms: either an AND message (if x and y are triggered, the message is passed on); or an OR message (if x or y is triggered, the message is passed on).

Arguably, nowhere is this more complex than in the dense, wrinkled outer section of the human central nervous system; the cerebral cortex. The deeper second and third layers are especially thick, packed with branches that carry out high order functions we associate with sensation, thought, and motor control.

It was tissues from these layers that the researchers took a close look at, hooking up cells to a device called a somatodendritic patch clamp to send active potentials up and down each neuron, recording their signals.

There was a 'eureka' moment when  scientists saw the dendritic action potentials for the first time.

To ensure any discoveries weren't unique to people with epilepsy, they double checked their results in a handful of samples taken from brain tumors.

While the team had carried out similar experiments on rats, the kinds of signals they observed buzzing through the human cells were very different.

More importantly, when they dosed the cells with a sodium channel blocker called tetrodotoxin, they still found a signal. Only by blocking calcium did all fall quiet.

Finding an action-potential mediated by calcium is interesting enough. But modelling the way this sensitive new kind of signal worked in the cortex revealed a surprise.

In addition to the logical AND and OR-type functions, these individual neurons could act as 'exclusive' OR (XOR) intersections, which only permit a signal when another signal is graded in a particular fashion.

More work needs to be done to see how dCaAPs behave across entire neurons, and in a living system. Not to mention whether it's a human-thing, or if similar mechanisms have evolved elsewhere in the animal kingdom.

https://www.science.org/doi/10.1126/science.aax6239

Part 2

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Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 12:40pm

A First-of-Its-Kind Signal Has Been Detected in The Human Brain

Scientists have recently identified a unique form of cell messaging occurring in the human brain that's not been seen before.

Excitingly, the discovery hints that our brains might be even more powerful units of computation than we realized.

In 2020, researchers  reported a mechanism in the brain's outer cortical cells that produces a novel 'graded' signal all on its own, one that could provide individual neurons with another way to carry out their logical functions.

By measuring the electrical activity in sections of tissue removed during surgery on epileptic patients and analyzing their structure using fluorescent microscopy, the neurologists found individual cells in the cortex used not just the usual sodium ions to 'fire', but calcium as well.

This combination of positively charged ions kicked off waves of voltage that had never been seen before, referred to as a calcium-mediated dendritic action potentials, or dCaAPs.

Brains – especially those of the human variety – are often compared to computers. The analogy has its limits, but on some levels they perform tasks in similar ways.

Both use the power of an electrical voltage to carry out various operations. In computers it's in the form of a rather simple flow of electrons through intersections called transistors.

In neurons, the signal is in the form of a wave of opening and closing channels that exchange charged particles such as sodium, chloride, and potassium. This pulse of flowing ions is called an action potential.

Instead of transistors, neurons manage these messages chemically at the end of branches called dendrites.

"The dendrites are central to understanding the brain because they are at the core of what determines the computational power of single neurons.

Part 1

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 12:28pm

Mosquito Saliva Can Actually Suppress Our Immune System, Study Finds

We know mosquitoes are a serious threat to our health as human beings– in fact, they're the world's deadliest animal, with mosquito-borne diseases responsible for more than a million deaths a year.

And it's not just their bites that we need to worry about. New research shows how the saliva of a mosquito carrying the  dengue virus is loaded with a substance that may suppress our immune system response and increase the risk of infection.

Through three separate analysis methods, scientists identified a specific type of viral RNA, or chemical messenger, called sfRNA in the infected mosquito saliva. It essentially blocks the defense mechanisms the human body puts up against infection.

It's incredible that the virus can hijack these molecules so that their co-delivery at the mosquito bite site gives it an advantage in establishing an infection.

These findings provide new perspectives on how we can counteract dengue virus infections from the very first bite of the mosquito.

The sfRNA is loaded in membrane compartments called extracellular vesicles, ready for delivery. The dengue virus appears to "subvert mosquito biology", in the words of the researchers, to give it a better chance of spreading. In tests on immortalized cell lines, the team confirmed that this sfRNA payload did indeed increase virus infection levels – laying the groundwork so that the human body isn't quite so well prepared for attack. These sfRNAs have been spotted before in insect-borne viruses, including Zika and yellow fever. Their role, more generally, seems to be to get in the way of the chemical signaling used by the body as the virus replicates.

Right now, there's no way of treating the virus, only methods for managing the symptoms. While we're still some way from a drug to treat dengue, understanding more about it and how it spreads is essential in fighting it.

https://journals.plos.org/plospathogens/article?id=10.1371/journal....

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 11:13am

How electricity can heal wounds three times faster

Chronic wounds are a major health problem for diabetic patients and the elderly—in extreme cases they can even lead to amputation. Using electric stimulation, researchers have developed a method that speeds up the healing process, making wounds heal three times faster.

For most people, a small wound does not lead to any serious complications, but many common diagnoses make wound healing far more difficult. People with diabetes, spinal injuries or poor blood circulation have impaired wound healing ability. This means a greater risk of infection and chronic wounds—which in the long run can lead to such serious consequences as amputation.

Electric guidance of cells for faster healing
The researchers worked from an old hypothesis that electric stimulation of damaged skin can be used to heal wounds. The idea is that skin cells are electrotactic, which means that they directionally "migrate" in electric fields. This means that if an electric field is placed in a petri dish with skin cells, the cells stop moving randomly and start moving in the same direction.

The researchers investigated how this principle can be used to electrically guide the cells in order to make wounds heal faster. Using a tiny engineered chip, the researchers were able to compare wound healing in artificial skin, stimulating one wound with electricity and letting one heal without electricity. The differences were striking.

Researchers were able to show that the old hypothesis about electric stimulation can be used to make wounds heal significantly faster. In order to study exactly how this works for wounds, they developed a kind of biochip on which they cultured skin cells, which they then made tiny wounds in. Then they stimulated one wound with an electric field, which clearly led to it healing three times as fast as the wound that healed without electric stimulation.

In the study, the researchers also focused on wound healing in connection with diabetes, a growing health problem worldwide. One in 11 adults today has some form of diabetes according to the World Health Organization (WHO) and the International Diabetes Federation.

The researchers have also looked at diabetes models of wounds and investigated whether this method could be effective even in those cases. They saw that when they mimicked diabetes in the cells, the wounds on the chip healed very slowly. However, with electric stimulation they could increase the speed of healing so that the diabetes-affected cells almost corresponded to healthy skin cells.

Sebastian Shaner, Anna Savelyeva, Anja Kvartuh, Nicole Jedrusik, Lukas Matter, José Leal, Maria Asplund. Bioelectronic microfluidic wound healing: a platform for investigating direct current stimulation of injured cell collectives. Lab on a Chip, 2023; 23 (6): 1531 DOI: 10.1039/D2LC01045C

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 10:50am

Chandra X-ray Observatory identifies new stellar danger to planets

Astronomers using data from NASA's Chandra X-ray Observatory and other telescopes have identified a new threat to life on planets like Earth: a phase during which intense X-rays from exploded stars can affect planets over 100 light-years away. This result has implication for the study of exoplanets and their habitability.

This newly found threat comes from a supernova's blast wave striking dense gas surrounding the exploded star. When this impact occurs it can produce a large dose of X-rays that reaches an Earth-like planet months to years after the explosion and may last for decades. Such intense exposure may trigger an extinction event on the planet.

A new study reporting this threat is based on X-ray observations of 31 supernovae and their aftermath—mostly from NASA's Chandra X-ray Observatory, Swift and NuSTAR missions, and ESA's XMM-Newton—show that planets can be subjected to lethal doses of radiation located as much as about 160 light-years away. Four of the supernovae in the study (SN 1979C, SN 1987A, SN 2010jl, and SN 1994I) are shown in composite images containing Chandra data in the supplemental image.

If a torrent of X-rays sweeps over a nearby planet, the radiation could severely alter the planet's atmospheric chemistry. For an Earth-like planet, this process could wipe out a significant portion of ozone, which ultimately protects life from the dangerous ultraviolet radiation of its host star. It could also lead to the demise of a wide range of organisms, especially marine ones at the foundation of the food chain, leading to an extinction event.

 Ian R. Brunton et al, X-Ray-luminous Supernovae: Threats to Terrestrial Biospheres, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/acc728

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 10:32am

How Do Greenhouse Gases Actually Work?

Comment by Dr. Krishna Kumari Challa on April 21, 2023 at 10:16am

Eighteen international experts contributed to the study. Just published in the journal Science, it is the outcome of a virtual scientific workshop held in December 2020, which 62 researchers from 35 countries attended. 

In their study, the experts describe the rapidly worsening loss of species with the aid of sobering figures: they estimate that human activities have altered roughly 75% of the land surface and 66% of the marine waters on our planet. This has occurred to such an extent that today, approximately 80% of the biomass from mammals and 50% of plant biomass has been lost, while more species are in danger of extinction than at any time in human history. In this regard, global warming and the destruction of natural habitats not only lead to biodiversity loss, but also reduce the capacity of organisms, soils and sediments to store carbon, which in turn exacerbates the climate crisis.

Because each organism has a certain tolerance range for changes to its environmental conditions (e.g., temperature), global warming is also causing species' habitats to shift. Mobile species follow their temperature range and migrate toward the poles, to higher elevations (on land, mountain ranges) or to greater depths (in the ocean). Sessile organisms like corals can only shift their habitats very gradually, in the course of generations: as such, they are caught in a temperature trap, which means that large coral reefs could, in the long term, disappear entirely. And mobile species, too, could run into climatic dead ends in the form of mountain summits, the coasts of landmasses and islands, at the poles and in the ocean's depths, if they can no longer find any habitat with suitable temperatures to colonize. In order to address these multiple crises, the researchers propose an ambitious combination of emissions reduction, restoration and protection measures, intelligent land-use management, and promoting cross-institutional competencies among political actors. Needless to say, a massive reduction of greenhouse-gas emissions and reaching the 1.5-degree target continue to be at the top of the priorities list.

 H.-O. Pörtner, Overcoming the coupled climate and biodiversity crises and their societal impacts, Science (2023). DOI: 10.1126/science.abl4881. www.science.org/doi/10.1126/science.abl4881

Part 2

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