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Comment by Dr. Krishna Kumari Challa on June 21, 2023 at 10:35am

Penguin propulsion: The physics behind the world's fastest swimming birds

Penguins aren't just cute: they're also speedy. Gentoo penguins are the fastest swimming birds in the world, and that ability comes from their unique and sophisticated wings.

Researchers  developed a model to explore the forces and flow structures created by penguin wings underwater. They determined that wing feathering is the main factor for generating thrust. Their findings have been published in the journal Physics of Fluids.

Penguin wings, aka flippers, bear some resemblance to airplane wings covered with scaly feathers. To maximize efficiency underwater instead of in the air, penguin wings are shorter and flatter than those of flying birds.

The animals can adjust swimming posture by active wing feathering (changing the angle of their wings to reduce resistance), pitching, and flapping. Their dense, short feathers can also lock air between the skin and water to reduce friction and turbulence.

Penguins' superior swimming ability to start/brake, accelerate/decelerate, and turn swiftly is due to their freely waving wings. They allow penguins to propel and maneuver in the water and maintain balance on land.

Hydrodynamic performance of a penguin wing: Effect of feathering and flapping, Physics of Fluids (2023). DOI: 10.1063/5.0147776

Comment by Dr. Krishna Kumari Challa on June 20, 2023 at 11:50am

Phase transitions are very common. The term refers to how a material changes from one state to another. A solid melts into a liquid, a liquid boils into a gas. A metal transitions from a normal state to a superconducting one. Each of these has a tipping point at which an equilibrium state undergoes a profound shift into another state.

Their results showed that we're not necessarily headed for certain climate doom. We might follow quite a regular and predictable trajectory, the endpoint of which is a climate stabilization at a higher average temperature point than what we have now. That's… still not great, given the deadly effects we're already seeing on humans and other animals.

But at the more extreme end, Earth runs into havoc. This means that the Earth's system evolves into chaotic behavior – extreme seasonal fluctuations and weather events – that precludes prediction of the future behavior of the system, making it impossible to mitigate. That means it would be extremely difficult, if not impossible, to claw our way back to a stable climate.

Even for this simple case, we observed the emergence of chaotic behavior in the equilibrium points of the Earth system. This leads to potentially important consequences if at least some components of the human activities actually follow logistic maps, which is a quite reasonable hypothesis, given the physical limitations of the planet-wide system we live in."

This outcome isn't inevitable, which is something of a relief. But, the researchers say we need to consider it a real possibility for designing strategies to mitigate climate change and manage the Earth system in the future.

https://arxiv.org/abs/2204.08955

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Part 2

Comment by Dr. Krishna Kumari Challa on June 20, 2023 at 11:48am

Earth Could Feasibly Descend Into Chaos, Physicists Warn

The impact of human activity on the Earth system could result in unpredictable chaos from which there is no return, physicists have calculated.

Using a theory conceived to model superconductivity, a team of physicists showed that, after a certain point, we will not be able to restore equilibrium to Earth's climate. A finite amount of human activity could result in a Hothouse Earth from which there is no return. They detailed their work in a paper made available in April 2022 on the preprint server arXiv that remains to be peer-reviewed.

If the Earth System gets into the region of chaotic behavior, we will lose all hope of somehow fixing the problem, they warn.

For some years now, extreme weather events seem to be occurring more regularly. Wildfires blaze, storms rage, temperatures reach new records. Climate scientists have warned that this is a consequence of human activity, such as the burning of fossil fuels, deforestation, and increases in farming.

This has led to the proposal of a new geological epoch: the Anthropocene, a period in which human activity has led to a significant and marked impact on the entire Earth system, comprised of the geosphere, biosphere, hydrosphere, and atmosphere.

The Anthropocene would follow the Holocene, which started around 11,700 years ago, and scientists propose its beginning around the middle of the 20th century – the peak of the nuclear era.

Part 1

Comment by Dr. Krishna Kumari Challa on June 20, 2023 at 11:40am

Special Nasal Drops Could Help The Brain Recover After A Stroke

Scientists have demonstrated how nasal drops containing a particular molecule can help mice recover from the damaging biological consequences of a stroke – and the hope is that the treatment could eventually be transferred to humans.

Crucially, the treatment isn't applied straight away but is initiated seven days after the stroke. That means those who are unable to be assisted immediately after a stroke could still be protected against the worst effects of the condition.

The key molecule in the drops is the complement peptide (a chain of amino acids) C3a, which we already know plays an important role in the body's immune system, as well as in the development and plasticity of the brain.

If the treatment is used in clinical practice, all stroke patients could receive it, even those who arrive at the hospital too late for thrombolysis or thrombectomy. Those who have remaining disability after the clot is removed could improve with this treatment too.

The delay is actually deliberate. Applied too early, the C3a peptide can increase the number of inflammatory cells in the brain, where they would start doing more harm than good.

Scientists induced an artificial ischemic stroke, the most common type of stroke there is, in mice. After a week, however, the nasal drops proved to help mice recover motor function faster and more completely, compared to a placebo group.

The new study also gives us a better idea of the effect of C3a on the brain. MRI scans revealed that the peptide helped to increase the number of connections between nerve cells in the brains of the mice.

The results show that the C3a peptide affects the function of astrocytes – that is, cells that control many of the nerve cells' functions in both the healthy and the diseased brain – and which signals astrocytes send to nerve cells.

https://www.jci.org/articles/view/162253

Comment by Dr. Krishna Kumari Challa on June 20, 2023 at 10:56am

How to reduce exposure to pollutants from gas stoves

Beyond ensuring proper ventilation with a range hood or open window, relatively low-cost approaches to reducing exposure to pollutants from gas stoves include:

• Use portable induction cooktops, which can be found for less than $50 new.
• Use electric kitchenware, such as tea kettles, toaster ovens, and slow cookers.
• Where available, take advantage of state and local rebates as well as low- or no-interest loans (such as these programs for California and the San Francisco Bay Area) to offset the cost of replacing gas appliances.
• Federal tax credits are available now, and federal rebates should be available later this year or sometime in 2024 to help offset the cost of replacing gas appliances.

 Yannai S. Kashtan et al, Gas and Propane Combustion from Stoves Emits Benzene and Increases Indoor Air Pollution, Environmental Science & Technology (2023). DOI: 10.1021/acs.est.2c09289

Part 2

Comment by Dr. Krishna Kumari Challa on June 20, 2023 at 10:55am

Study finds combustion from gas stoves can raise indoor levels of chemical linked to blood cell cancers

A chemical linked to a higher risk of leukemia and other blood cell cancers creeps into millions of homes whenever residents light their gas stoves. A new Stanford-led analysis finds that a single gas cooktop burner on high or a gas oven set to 350 degrees Fahrenheit can raise indoor levels of the carcinogen benzene above those in secondhand tobacco smoke. Benzene also drifts throughout a home and lingers for hours in home air, according to the paper published in Environmental Science & Technology.

Benzene forms in flames and other high-temperature environments, such as the flares found in oil fields and refineries. We now know that benzene also forms in the flames of gas stoves in our homes. Good ventilation helps reduce pollutant concentrations, but it was found that exhaust fans were often ineffective at eliminating benzene exposure.

Overall, the researchers found that indoor concentrations of benzene formed in the flames of gas stoves can be worse than average concentrations from secondhand smoke, that benzene can migrate into other rooms far from the kitchen, and that concentrations measured in bedrooms can exceed national and international health benchmarks. They also found residential range hoods are not always effective at reducing concentrations of benzene and other pollutants, even when the hoods vent outdoors.

The researchers also tested whether foods being cooked emit benzene and found zero benzene emissions from pan-frying salmon or bacon. All benzene emissions the investigators measured came from the fuel used rather than any food cooked.

Part 1

Comment by Dr. Krishna Kumari Challa on June 19, 2023 at 11:48am

NASA finds key building block for life in a moon of Saturn

Scientists have discovered that phosphorus, a key building block of life, lies in the ocean beneath the icy surface of Saturn's moon Enceladus. The finding was based on a review of data collected by NASA's Cassini probe, and was published Wednesday in the prestigious journal Nature.

Cassini started exploring Saturn and its rings and moons in 2004, before burning up in the gas giant's atmosphere when its mission ended in 2017.

NASA found abundant phosphorus in plume ice samples spraying out of the subsurface ocean.

Scientists previously found other minerals and organic compounds in the ejected ice grains, but not phosphorus, which is an essential building block for DNA and RNA, and is also found in the bones and teeth of people, animals, and even ocean plankton.

Simply put, life as we know it would not be possible without phosphorus.

It's the first time this essential element has been discovered in an ocean beyond Earth.

With this finding, the ocean of Enceladus is now known to satisfy what is generally considered to be the strictest requirement for life. The next step is clear –- we need to go back to Enceladus to see if the habitable ocean is actually inhabited.

Frank Postberg, Detection of phosphates originating from Enceladus's ocean, Nature (2023). DOI: 10.1038/s41586-023-05987-9. www.nature.com/articles/s41586-023-05987-9

Comment by Dr. Krishna Kumari Challa on June 17, 2023 at 10:36am

At each stage of its life cycle, the parasite must logically pick up signals that enable it to react correctly.

There are small molecules  absent in the blood but present in the mosquito that the parasite is able to detect. Starting from this single known element, scientists have identified a sensor that enables the parasite to detect the presence of these molecules when it is ingested by a mosquito.

This sensor is made up of five proteins. In its absence, the parasite does not realize that it has left the bloodstream for the mosquito, and is therefore unable to continue its development.

Surprisingly, this sensor is also present at other stages of the parasite lifecycle, notably when the parasite has to leave the red blood cell. Scientists then observe exactly the same mechanism: without this sensor, Plasmodium is trapped in the red blood cells, unable to continue its infection cycle.

The protein complex discovered here is absent in humans, but is found in the entire family of apicomplexan parasites to which Plasmodium belongs, as well as Toxoplasma, the agent of toxoplasmosis. By identifying this sensor, scientists can now imagine how to scramble the signals perceived by the parasite at different stages of its development, thus disorienting it and blocking its multiplication and transmission.

Ronja Kühnel et al, A Plasmodium membrane receptor platform integrates cues for egress and invasion in blood forms and activation of transmission stages, Science Advances (2023). DOI: 10.1126/sciadv.adf2161. www.science.org/doi/10.1126/sciadv.adf2161

Part 2

Comment by Dr. Krishna Kumari Challa on June 17, 2023 at 10:33am

Scientists think disorienting the malaria parasite may prevent it from causing harm

With almost 250 million cases a year, 621,000 of them fatal, malaria remains a major public health problem, particularly in sub-Saharan Africa. Malaria is a parasitic disease transmitted by mosquitoes and caused by a microbe of the genus Plasmodium. On its journey from mosquito to human, Plasmodium must adapt to the specificities of the many organs and cells it parasitizes. Microbes do not have sensory organs; instead, they have sensors made of proteins to detect molecules specific to the environments they colonize. While most living organisms share the same types of sensors, Plasmodium is an exception.

Biologists have identified a new type of sensor that enables Plasmodium to know precisely where it is and what to do. This work, published in the journal Science Advances, opens up the possibility of scrambling the signals perceived by this sensor to disorient the parasite and thus prevent its replication and transmission.

When a human is bitten by a Plasmodium-infected mosquito, the parasite enters the bloodstream and travels to the liver, where it thrives for around 10 days without causing any symptoms. After this period, Plasmodium re-enters the bloodstream, where it parasitizes red blood cells. Once inside the red blood cells, the parasites multiply in a synchronized 48-hour cycle.

At the end of each multiplication cycle, the newly-formed parasites leave their host red blood cells, destroying them and infecting new ones. It is this destruction of red blood cells that causes the waves of fever associated with malaria. Severe forms of malaria are linked to the obstruction of blood vessels by infected red blood cells.

When a mosquito bites a human whose blood is infected with Plasmodium, the parasite changes its development program to colonize the intestine of its new host. After a further period of multiplication, Plasmodium returns to the mosquito's salivary glands, ready to infect a new human.

From the warmth of the red blood cell to the depths of the mosquito's intestine via the liver, how does Plasmodium perceive changes in its environment in order to change its development program? Understanding this very specific biological mechanism is an important step towards countering the parasite.

Part 1

Comment by Dr. Krishna Kumari Challa on June 17, 2023 at 10:01am

Study finds that the human brain reactivates mental representations of past events during new experiences

Neuroscience studies have showed that as mice and other rodents navigate a maze, their brain often "replays" relevant past events. This mental replaying of events, such as the route taken until reaching their current position, could help rodents create a mental map of the spatial environment, and understand their position in it.

Researchers  recently explored the possibility that the human brain also replays past events to make sense of evolving, non-spatial experiences. Their findings, published in Nature Neuroscience, confirms this hypothesis and suggests that the process through which the human brain reactivates these events might be far more complex than that observed in rodents.

Researchers tried to devise an experiment that might elicit the replay of past events as observed in rodents, but during non-spatial daily experiences. Ultimately, they decided to ask their participants to watch a movie or listen to audio recordings of a narrated story while recording their brain activity using a functional magnetic resonance imaging (fMRI) scanner.

Movies and stories simulate real world experiences, as they are composed of events that should be linked together to understand the overall narrative.

Interestingly, researchers  found that as participants were engaged in the narrative of a movie or story, representations of past events, which were needed to make sense of each present scene, were reactivated in their brain. Unlike in rodents, these reactivations appeared while the participants were watching the movie or listening to the story, rather than during periods of rest from the task.

They found that the same brain regions that replay spatial information in the rodent brain also replay narrative events in the human brain. In other words, replay, previously thought to mainly support spatial navigation, could also underlie the human ability to make sense of narratives.  

Overall, the recent work by this team of researchers suggests that while humans are trying to make sense of their present experiences, their brain may continuously reactivate relevant past events. 

Avital Hahamy et al, The human brain reactivates context-specific past information at event boundaries of naturalistic experiences, Nature Neuroscience (2023). DOI: 10.1038/s41593-023-01331-6

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