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Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 11:31am

There exists a fundamental limit to what can be predicted with turbulence," according to researchers. "You see this with weather forecasts; there is always a fundamental source of randomness. The precise sense in which this unpredictability was inevitable wasn't fully understood before this work."

It's that randomness that makes it so hard to accurately predict the weather more than a few hours in advance. Meteorological stations sample weather in select locations, and computer simulations stitch them together, but without knowing the exact weather everywhere right now, it's hard to predict the exact weather everywhere in the future. This paper hints at the possibility that fundamental limits will always exist because randomness will always show up.

There may also be implications in astrophysics research. Scientists already understand that computer simulations of how galaxies are formed and how our universe evolved are sensitive to noise. Often, the behaviours of stars, planets, and galaxies cannot be easily explained and may be attributed to the kinds of microscopic noise that researchers have uncovered now.

Dmytro Bandak et al, Spontaneous Stochasticity Amplifies Even Thermal Noise to the Largest Scales of Turbulence in a Few Eddy Turnover Times, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.104002. On arXiv: DOI: 10.48550/arxiv.2401.13881

Part 2

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 11:28am

New research shows turbulent flows can be caused by minute triggers

We experience turbulence every day: a gust of wind, water gushing down a river, or mid-flight bumps on an airplane.

Although it may be easy to understand what causes some kinds of turbulence—a felled tree in a river or a bear splashing around for salmon—there is now evidence that a very small disturbance at the start can have dramatic effects later. Instead of a tree, think of a twig—or even the swerving motion of a molecule.

The butterfly effect

A butterfly flaps its wings in Brazil, which later causes a tornado in Texas. Although we may commonly use the phrase to denote the seeming interconnectedness of our own lives, the term "butterfly effect" is sometimes associated with chaos theory. Researchers said their work represents a more extreme version of the butterfly effect, first described by mathematician and meteorologist Edward Lorenz in 1969.

What researchers have learned is that in turbulent systems, a very small disturbance at one point will have an amplified effect at a finite point in the future, but through a mechanism that is faster than chaos.

Although the mathematical mechanism for this amplification, known as spontaneous stochasticity, was discovered about 25 years ago. The fact that the random motion of molecules, responsible for the everyday phenomenon of temperature, could generate spontaneous stochasticity was not known before this work.

Thinking back on the twig in the river, while you might notice a small disturbance where the water flows over the twig, you wouldn't expect it to create a great deal of turbulence (via eddies and swirls) downstream. Yet that is precisely what this new paper shows. The mechanism is known as spontaneous stochasticity, because the randomness arises even though the fluid motion was expected to be predictable.

Furthermore, it would be impossible to pinpoint the twig that had originally set the eddies and swirls in motion. In fact, there may be no disturbance in the water flow where the twig is located at all.

The research team's findings also showed that spontaneous stochasticity happens regardless of the initial disturbance. Whether it's a twig, a pebble, or a clod of dirt, the randomness you get on a large scale is the same. In other words, the randomness is intrinsic to the process.

Part 1

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 11:18am

A coral superhighway in the Indian Ocean

New research has revealed that, despite being scattered across more than a million square kilometers, remote coral reefs across the Seychelles are closely related. Using genetic analyses and oceanographic modeling, researchers have demonstrated for the first time that a network of ocean currents scatter significant numbers of larvae between these distant islands, acting as a "coral superhighway."

This discovery is very important because a key factor in coral reef recovery is larval supply. Although corals have declined alarmingly across the world due to climate change and a number of other factors, actions can be taken at local and national scale to improve reef health and resilience.

These actions can be more effective when we better understand the connectivity between coral reefs, by—for instance—prioritizing conservation efforts around coral reefs that act as major larval sources to support regional reef resilience.

The researchers collaborated with a wide range of coral reef management organizations and the Seychelles government to collect coral samples from 19 different reef sites. A comprehensive genetic analysis revealed recent gene flow between all sample sites—possibly within just a few generations—suggesting that coral larvae may be frequently transferred between different populations. The results also hinted at the existence of a new cryptic species of the common bouldering coral, Porites lutea.

The genetic analyses were then coupled with oceanographic modeling, simulating the process of larval dispersal. These simulations allowed researchers to visualize the pathways coral larvae take to travel between reefs across the wider region, and determine the relative importance of physical larval dispersal versus other biological processes in setting coral connectivity.

This revealed that dispersal of coral larvae directly between reefs across the Seychelles is highly plausible. For example, coral larvae spawned at the remote Aldabra atoll could disperse westwards towards the east coast of Africa via the East African Coastal Current. From here, they would then travel north along the coast, with some potentially even reaching the South Equatorial Counter Current, which could bring them eastwards again back towards the Inner Islands of Seychelles.

While these long-distance dispersal events are possible, it is likely that much of the connectivity between remote islands across the Seychelles may be established through "stepping-stone" dispersal. This suggests that centrally located coral reefs in Seychelles, and possibly East Africa, may play an important role in linking the most remote islands.

Integration of population genetics with oceanographic models reveals strong connectivity among coral reefs across Seychelles, Scientific Reports (2024). DOI: 10.1038/s41598-024-55459-x

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 10:50am

Rainforest's next generation of trees threatened 30 years after logging

Rainforest seedlings are more likely to survive in natural forests than in places where logging has happened—even if tree restoration projects have taken place, new research shows. The work appears in Global Change Biology.

Scientists monitored over 5,000 seedlings for a year and a half in North Borneo.

They studied a landscape containing both natural forest and areas logged 30 years ago—some of which were recovering naturally, while some had been restored by methods including tree planting.

A drought had triggered "mast fruiting" across the region, with trees simultaneously dropping fruit en masse and new seedlings emerging.

At first, both natural forest and restored forest had similarly high numbers of seedlings, compared to naturally recovering forest—suggesting restoration activities enhanced fruit production.

But these benefits did not last: low seedling survival in the restored forest meant that by the end of the study, similarly low numbers of seedlings remained in restored and naturally recovering forest. Seedling populations remained higher in natural forest.

Together, these results show that regeneration may be challenged by different factors depending on the restoration approach—seed availability in naturally recovering sites and seedling survival in sites where planted trees have matured. These differences may have longer-term implications for how forests can deliver key ecosystem services such as carbon sequestration.

Bornean tropical forests recovering from logging at risk of regeneration failure Running Title: Seedling responses to logging and restoration., Global Change Biology (2024).

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 10:00am

How invisible presences hijack the social counting brain in Parkinson's disease

If you had to estimate the number of people in a room, without counting them one by one, by nature you would overcount them. That's because—simply put from a Darwinian perspective of how we have evolved—it's better to overcount potentially harmful agents and predators than to underestimate them. This overcounting social behavior is shown to be true in humans as well as animals. It's certainly better to detect too many tigers (even if absent) during a jungle excursion than to miss a hungry one.

Now,  neuroscientists show that if you experience hallucinations, especially when related to an illness like Parkinson's disease, then you will overestimate the number of people in a room to a greater degree. They also show that if you have hallucinations but are asked to estimate the number of boxes in a room, which are inanimate control objects, then no extra overestimation occurs, shedding light on the social nature of this overcounting.

The results are published in Nature Communications.

The fact that patients of Parkinson's disease have a much higher over-estimation in counting people is mind-blowing because Parkinson's disease is classically viewed as a movement disorder.

This new work shows that Parkinson's may also be a perceptual disorder, especially of social stimuli, and that invisible presences in Parkinson's disease may impair even more the counting social brain.

The category of hallucinations investigated by the neuroscientists is called presence hallucinations, for which people report an invisible presence next to them, even though no one is there. Such hallucinations are considered to be minor compared to visual hallucinations, for instance. They may be experienced early on in patients with Parkinson's disease, sometimes even before diagnosis. Presence hallucinations are also a known early marker of cognitive decline in Parkinson's disease.

The results of the study support the idea that the invisible presence (and related brain mechanisms) are responsible for this overcounting of people. When presence hallucinations are experienced—either due to disease or induced artificially—this extra presence gets subconsciously translated into an over-estimation of the number of people we think we see. In essence, the invisible presence gets added in the counting process, but only in counting people.

Nature Communications (2024).

https://www.nature.com/articles/s41467-024-45912-w

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 9:47am

Age-related changes in skin may contribute to melanoma metastases

Age-related changes that cause the skin to stiffen and become less elastic may also contribute to higher rates of metastatic skin cancer in older people, according to research by investigators.

 The study, published March 12 in Nature Aging, shows that increased stiffness in aging skin increases the release of a protein called ICAM1. Increased ICAM1 levels stimulate blood vessel growth in the tumor, helping it grow. It also makes the blood vessels "leaky," enabling tumor cells to escape and spread throughout the body more easily.

The discoveries might also lead to new approaches to treating other age-related cancers. Previous therapies targeting growth factors that contribute to angiogenesis have failed in many tumor types, including melanoma. But ICAM1 provides a promising new target.

Nature Aging (2024).

• Age-Related Lung Changes Provide Pathway for Metastatic Growth of D...
• Age is a primary determinant of melanoma treatment resistance, two ...

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 9:40am

Spring irrigation can reduce summer heat wave events

Heat waves are becoming more extreme as climate change exacerbates, with susceptible locations experiencing more frequent, prolonged and higher intensity events. As such, they pose a hazard to agricultural practices that rely upon sufficient water to ensure sustainable food supplies.

Irrigation is used to help alleviate warm, dry climates by maintaining soil moisture levels to promote growth as well as exerting a cooling effect on the immediate local climate (within a few meters of the surface), but extracts freshwater from resources that may also be threatened by shrinkage with more evaporation in a warmer world.

New research, published in Geophysical Research Letters, has investigated the dampening effect irrigating land in spring can have on the intensity of summer heat waves by retaining higher soil moisture levels between seasons, known as soil moisture memory.

The researchers  analyzed models of root-zone soil moisture data from 1980 to 2018 and combined this with a forecasting model to simulate the effect of irrigation on extreme summer heat wave events from 2004 to 2018. They ran three tests, one with no irrigation, one with both spring and summer irrigation, and the last solely with spring irrigation.

The researchers found that spring irrigation reduced the intensity of summer heat waves by 0.29°C and 2.5 days, and when combined with summer irrigation this extends to a reduction of 1°C and 6.5 days. With the simulated regional means of extreme heat waves being temperatures of 35.8°C and lasting 21.7 days, the combined impact of spring and summer irrigation can have a significant effect, especially on the longevity of the event.

This research is important as it suggests applying a surplus of water in spring helps to alleviate water stress in the following summer months, and is less wasteful of water resources that evaporate more in summer (especially from the top 1 m of soil), while also supporting regions that experience an imbalance in precipitation through the year.

Though the intensity of extreme heat wave events may be reduced, these climatic challenges will persist in the future, so it is important to apply these results in water resource management and adaptation planning strategies.

Guoshuai Liu et al, Spring Irrigation Reduces the Frequency and Intensity of Summer Extreme Heat Events in the North China Plain, Geophysical Research Letters (2024). DOI: 10.1029/2023GL107094

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 9:15am

False GPS signal surge makes life hard for pilots

False GPS signals that deceive on-board plane systems and complicate the work of airline pilots are surging near conflict zones.

A ground collision alert sounds in the cockpit, for instance, even though the plane is flying at high altitude—a phenomenon affecting several regions and apparently of military origin.

This includes the vicinity of Ukraine following the Russian invasion two years ago, the eastern Mediterranean and the air corridor running above Iraq, according to pilots and officials.

Disruptions which were previously limited to jamming preventing access to signals from geolocation satellites are now also taking a more dangerous form making it difficult to counter spoofing.

This sees a plane receive false coordinates, times and altitudes.

By comparing this data to the geographical maps in its memory banks, its systems can conclude there is imminent danger ahead. There were some untimely alarms ordering people to pull back as far as possible on the stick and apply full power to avoid an obstacle, while the plane was in cruise... and in any case no mountain reaches so high.

The problem  is that this adulterated information enters the navigation system and can cause false alerts hours afterwards as the flight nears its destination.

At first, crews quickly see that it is a false alarm. But as it is an alarm warning of immediate danger, control towers ask the crews to still carry out the emergency maneuver, to make a return and an analysis. If the problem occurs a second time and the analysis has not revealed any danger, then the only way is to turn off this alarm, knowing other systems remain active to detect possible risk.

Since the start of the war in Ukraine, the European Union Aviation Safety Agency (EASA) has been warning that GNSS signal disruptions have intensified, affecting relatively remote regions beyond the conflict zone such as Finland and the Mediterranean.

In certain cases, this can lead to a modified trajectory or even a changed destination as it was impossible to carry out a landing in secure conditions, the EASA says.

Source: AFP and other news agencies

Comment by Dr. Krishna Kumari Challa on March 13, 2024 at 7:18am

For people who speak many languages, there's something special about their native tongue

A new study of people who speak many languages has found that there is something special about how the brain processes their native language.

In the brains of these polyglots—people who speak five or more languages ( I am one of them too!)—the same language regions light up when they listen to any of the languages that they speak. In general, this network responds more strongly to languages in which the speaker is more proficient, with one notable exception: the speaker's native language. When listening to one's native language, language network activity drops off significantly.

The findings suggest there is something unique about the first language one acquires, which allows the brain to process it with minimal effort, the researchers say.

Something makes it a little bit easier to process—maybe it's that you've spent more time using that language—and you get a dip in activity for the native language compared to other languages that you speak proficiently.

The brain's language processing network, located primarily in the left hemisphere, includes regions in the frontal and temporal lobes. In a 2021 study, researchers found that in the brains of polyglots, the language network was less active when listening to their native language than the language networks of people who speak only one language.

In the new study, the researchers wanted to expand on that finding and explore what happens in the brains of polyglots as they listen to languages in which they have varying levels of proficiency. Studying polyglots can help researchers learn more about the functions of the language network, and how languages learned later in life might be represented differently than a native language or languages.

With polyglots, you can do all of the comparisons within one person. You have languages that vary along a continuum, and you can try to see how the brain modulates responses as a function of proficiency.

Saima Malik-Moraleda et al, Functional characterization of the language network of polyglots and hyperpolyglots with precision fMRI, Cerebral Cortex (2024). DOI: 10.1093/cercor/bhae049

Comment by Dr. Krishna Kumari Challa on March 10, 2024 at 12:49pm

A look inside the Harvard Herbaria

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