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Comment by Dr. Krishna Kumari Challa on January 30, 2024 at 9:46am

In discussing possible reasons for this behavior among Coenobitidae, the team notes the environmental availability of plastic waste, along with the growing scarcity of gastropod shells due to localized human activities. The researchers also suggest factors involved in individual choice, including:

• Attractiveness of artificial materials to mating females
• Lighter artificial shell weights that might benefit hermit crabs' energy
• An odor cue of dimethyl sulfide, found in both natural shells and marine waste; and
• The possibility that artificial shells may serve more efficiently as camouflage in polluted areas, given that shell selection is often made to blend into the localized environment.

These are all topics for further investigation.

"Are artificial shells setting the scene for a novel evolutionary trajectory in hermit crabs, or are they an ecological and evolutionary trap of the Anthropocene?" the researchers ask.

While this new behavior might be considered a clever adaptation, the main factor behind it is undeniable. In that vein, what this habit ultimately means for the evolution of terrestrial hermit crabs remains to be studied.

 Zuzanna Jagiello et al, The plastic homes of hermit crabs in the Anthropocene, Science of the Total Environment (2024). DOI:/10.1016/j.scitotenv.2023.168959

Part 2

Comment by Dr. Krishna Kumari Challa on January 30, 2024 at 9:45am

On tropical coasts, hermit crabs are now making their homes in plastic waste

Terrestrial hermit crabs are soft-bodied crustaceans that live near water in the world's tropical areas. Without any natural protection of their own, these crabs normally find shelter in discarded mollusk shells. But a number of terrestrial hermit crab species are beginning to opt for artificial shells frequently consisting of plastic objects found in beach trash.

New research on this topic, described in a short communication by a team from the University of Warsaw's Biological and Chemical Research Center and the department of Zoology at Poland's Poznań University of Life Sciences, appears in Science of the Total Environment.

Plastic pollution, which is increasing, already comprises 85% of marine pollution worldwide. Existing research shows that most of the plastic pollution in Earth's oceans arrives there via rivers, leading to plastic waste accumulation on coastlines.

Terrestrial hermit crabs (Coenobitidae) live on all the world's tropical coastlines, and typically acquire empty shells of gastropods to protect their soft abdominal region, known as pleon. The shells protect them from predators and also keep their pleon from drying out.

Studies on the crabs' selection of shells have shown the main factors include chemical signals gleaned from shells; proximity of predators; quality of shells; and rate of individual crab growth. It has also been shown that shells play a role in sexual signaling, as the size and state of male crabs' shells affect females' mate choices.

Part 1

Comment by Dr. Krishna Kumari Challa on January 27, 2024 at 11:35am

Writing by hand may increase brain connectivity more than typing on a keyboard

As digital devices progressively replace pen and paper, taking notes by hand is becoming increasingly uncommon in schools and universities. Using a keyboard is recommended because it's often faster than writing by hand. However, the latter has been found to improve spelling accuracy and memory recall.

To find out if the process of forming letters by hand resulted in greater brain connectivity, researchers  now investigated the underlying neural networks involved in both modes of writing.

They showed that when writing by hand, brain connectivity patterns are far more elaborate than when typewriting on a keyboard. Such widespread brain connectivity is known to be crucial for memory formation and for encoding new information and, therefore, is beneficial for learning.

The researchers collected EEG data from 36 university students who were repeatedly prompted to either write or type a word that appeared on a screen. When writing, they used a digital pen to write in cursive directly on a touchscreen. When typing they used a single finger to press keys on a keyboard.

High-density EEGs, which measure electrical activity in the brain using 256 small sensors sewn in a net and placed over the head, were recorded for five seconds for every prompt.

Connectivity of different brain regions increased when participants wrote by hand, but not when they typed. These findings suggest that visual and movement information obtained through precisely controlled hand movements when using a pen contribute extensively to the brain's connectivity patterns that promote learning.

Although the participants used digital pens for handwriting, the researchers said that the results are expected to be the same when using a real pen on paper.

Their findings demonstrate the need to give students the opportunity to use pens, rather than having them type during class, the researchers said.

Handwriting but not Typewriting Leads to Widespread Brain Connectivity: A High-Density EEG Study with Implications for the Classroom, Frontiers in Psychology (2024). DOI: 10.3389/fpsyg.2023.1219945

Comment by Dr. Krishna Kumari Challa on January 27, 2024 at 11:28am

Stars travel more slowly at Milky Way's edge: Galaxy's core may contain less dark matter than previously estimated

By clocking the speed of stars throughout the Milky Way galaxy,  physicists have found that stars further out in the galactic disk are traveling more slowly than expected compared to stars that are closer to the galaxy's center. The findings raise a surprising possibility: The Milky Way's gravitational core may be lighter in mass, and contain less dark matter, than previously thought.

The new results are based on the researchers' analysis of data taken by the Gaia and APOGEE instruments. Gaia is an orbiting space telescope that tracks the precise location, distance, and motion of more than 1 billion stars throughout the Milky Way galaxy, while APOGEE is a ground-based survey.

The physicists analyzed Gaia's measurements of more than 33,000 stars, including some of the farthest stars in the galaxy, and determined each star's "circular velocity," or how fast a star is circling in the galactic disk, given the star's distance from the galaxy's center.

The scientists plotted each star's velocity against its distance to generate a rotation curve—a standard graph in astronomy that represents how fast matter rotates at a given distance from the center of a galaxy. The shape of this curve can give scientists an idea of how much visible and dark matter is distributed throughout a galaxy.

What they were really surprised to see was that this curve remained flat, flat, flat out to a certain distance, and then it started tanking. This means the outer stars are rotating a little slower than expected, which is a very surprising result.

The team translated the new rotation curve into a distribution of dark matter that could explain the outer stars' slow-down, and found the resulting map produced a lighter galactic core than expected. That is, the center of the Milky Way may be less dense, with less dark matter, than scientists have thought.

 Xiaowei Ou et al, The dark matter profile of the Milky Way inferred from its circular velocity curve, Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae034

Comment by Dr. Krishna Kumari Challa on January 26, 2024 at 8:49am

This "smart" material, called FG phase, is jelly-like and impenetrable for most macromolecules. It fills and blocks the nuclear pore channel. Importins and exportins, however, can pass through because their surfaces are optimized for sliding through an FG phase.

The cell's border control in the FG phase happens extremely fast—within milliseconds. Likewise, its transport capacity is enormous: A single nuclear pore can transfer up to 1,000 transporters per second through its channel. Even with such a high traffic density, the barrier of nuclear pores remains intact and keeps suppressing unwanted border crossings. HIV, however, subverts this control.
HIV packages its genome into a capsid. Recent evidence suggests that the genome stays inside the capsid until it reaches the nucleus, and thus also when passing the nuclear pore. But there is a size problem.
The central pore channel is 40 to 60 nanometers wide. The capsid has a width of about 60 nanometers and could just squeeze through the pore.

However, a normal cellular cargo would still be covered by a transporter layer that adds at least another ten nanometers. The HIV capsid would then be 70 nanometers wide—too big for a nuclear pore. Nevertheless, cryo-electron tomography has shown that the HIV capsid gets into the nuclear pore. But how this happens has been so far a mystery in HIV infection.

 Liran Fu et al, HIV-1 capsids enter the FG phase of nuclear pores like a transport receptor, Nature (2024). DOI: 10.1038/s41586-023-06966-w

Part 2

Comment by Dr. Krishna Kumari Challa on January 26, 2024 at 8:47am

How HIV smuggles its genetic material into the cell nucleus

Each year, about 1 million individuals worldwide become infected with HIV, the virus that causes AIDS. To replicate and spread the infection, the virus must smuggle its genetic material into the cell nucleus and integrate it into a chromosome.

Researchers have now discovered that its capsid has evolved into a molecular transporter. As such, it can directly breach a crucial barrier, which normally protects the cell nucleus against viral invaders. This way of smuggling keeps the viral genome invisible to anti-viral sensors in the cytoplasm. Their study is published in Nature. 

Forty years after the human immunodeficiency virus (HIV) was discovered as the cause of AIDS, we have therapies that effectively keep the pathogen under control, but there is still no cure. The virus infects certain immune cells and hijacks their genetic program in order to multiply and replicate its own genetic material. The infected cells then produce the next generation of viruses until they are finally destroyed. The immunodeficiency symptoms of AIDS result from the massive loss of immune cells that normally fight viruses and other pathogens.
To use the host cell's resources, HIV must smuggle its genetic material through cellular defense lines into the cell nucleus. The nucleus, however, is closely guarded. Its nuclear envelope prevents unwanted proteins or harmful viruses from entering the nucleus and macromolecules from an uncontrolled escape. Yet, selected proteins can pass because the barrier is not hermetically sealed.

Thousands of tiny nuclear pores in the nuclear envelope provide a passageway. They control these transport processes with the help of importins and exportins—molecular transporters that capture cargoes with valid molecular "passcodes" and deliver them through the nuclear pore channel. A "smart" material turns these pores into one of nature's most efficient sorting and transport machines.

Part 1

Comment by Dr. Krishna Kumari Challa on January 26, 2024 at 8:32am

Scientists discover the moon is shrinking, causing landslides and instability in lunar south pole

Earth's moon shrank more than 150 feet in circumference as its core gradually cooled over the last few hundred million years. In much the same way a grape wrinkles when it shrinks down to a raisin, the moon also develops creases as it shrinks. But unlike the flexible skin on a grape, the moon's surface is brittle, causing faults to form where sections of crust push against one another.

A team of scientists discovered evidence that this continuing shrinkage of the moon led to notable surface warping in its south polar region—including areas that NASA proposed for crewed Artemis III landings. Because fault formation caused by the moon's shrinking is often accompanied by seismic activity like moonquakes, locations near or within such fault zones could pose dangers to future human exploration efforts.

In a paper published in The Planetary Science Journal, the team linked a group of faults located in the moon's south polar region to one of the most powerful moonquakes recorded by Apollo seismometers over 50 years ago. Using models to simulate the stability of surface slopes in the region, the team found that some areas were particularly vulnerable to landslides from seismic shaking.

Shallow moonquakes occur near the surface of the moon, just a hundred or so miles deep into the crust. Similar to earthquakes, shallow moonquakes are caused by faults in the moon's interior and can be strong enough to damage buildings, equipment and other human-made structures.

But unlike earthquakes, which tend to last only a few seconds or minutes, shallow moonquakes can last for hours and even a whole afternoon.

Watters et al, Tectonics and Seismicity of the Lunar South Polar Region, The Planetary Science Journal (2024). DOI: 10.3847/PSJ/ad1332

Comment by Dr. Krishna Kumari Challa on January 26, 2024 at 8:26am

For this run the energy in the collision of the two protons was 13 trillion electron-volts, just below the machine's current maximum, which in more relatable units is 2.1 microjoules. That's about the kinetic energy of the average mosquito, or a grain of salt, traveling one meter per second.

Theory predicts that about 15 times per 10,000 decays, the Higgs boson should decay into a Z boson and a photon, the rarest decay in the Standard Model. It does so by first producing a pair of top quarks, or a pair of W bosons, which themselves then decay into the Z and photon.

The Atlas/CMS collaboration, work from more than 9,000 scientists, found a "branching ratio," or fraction of decays of 34 times per 10,000 decays, plus or minus 11 per 10,000—2.2 times the theoretical value.

The measured fraction is too large—3.4 standard deviations above the theoretical value, a number still too small to rule out a statistical fluke. Still, the relatively large difference hints at the possibility of a meaningful discrepancy from theory that could be due to physics beyond the Standard Model—new particles that are the intermediaries other than the top quark and W bosons.
One possibility for physics beyond the Standard Model is supersymmetry, the theory that posits a symmetry—a relationship—between particles of a half-spin, called fermions, and integer spin, called bosons, with every known particle having a partner with a spin differing by a half-integer.

Many theoretical physicists have long been advocates of supersymmetry as it would solve many conundrums that plague the Standard Model, such as the large difference (1024) between the strengths of the weak force and gravity, or why the mass of the Higgs boson, about 125 gigaelectron-volts (GeV), is so much less than the grand unification energy scale of about 1016 GeV.

G. Aad et al, Evidence for the Higgs Boson Decay to a Z Boson and a Photon at the LHC, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.021803

Part 2

Comment by Dr. Krishna Kumari Challa on January 26, 2024 at 8:25am

Rare decay of the Higgs boson may point to physics beyond the Standard Model

Particle physicists have detected a novel decay of the Higgs boson for the first time, revealing a slight discrepancy in the predictions of the Standard Model and perhaps pointing to new physics beyond it. 

The Higgs boson, predicted theoretically since the 1960s, was finally detected in 2012 at the CERN laboratory in Europe. As a quantum field it permeates all of space, through which other particles move, acquiring mass via their interaction with the Higgs field that can be roughly envisioned as a kind of resistance to their motion. Many properties of the Higgs boson, including how it interacts with other particle and their associated fields, have already been measured to be consistent with predictions of the Standard Model.

But one Higgs decay mode that had yet to be investigated was a theoretical prediction that a Higgs boson would occasionally decay and produce a photon, the quantum of light, and a Z boson, which is an uncharged particle that together with the two W bosons conveys the weak force.

Scientists from the ATLAS and CMS collaborations at CERN used data from proton-proton collisions taken from Run 2 from 2015 to 2018 to search for this particular Z+photon Higgs decay. The Large Hadron Collider (LHC) at CERN is the high-energy particle accelerator near Geneva, Switzerland that circulates protons in opposite directions while causing them to collide at specific detector points, millions of times per second.
Part 1

Comment by Dr. Krishna Kumari Challa on January 25, 2024 at 12:29pm

Science can only ascertain what is, but not what should be, and outside its domain value judgments of all kinds remain 

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