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Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:45am

How volcanic eruptions set off a chain of events that brought the Black Death to Europe
Volcanic eruptions around 1345 triggered consecutive years of cooling, leading to crop failures and famine in southern Europe. To prevent starvation, Italian city states imported grain from the Black Sea, inadvertently introducing Yersinia pestis via infected fleas on ships. This sequence of climate, agricultural, and trade events enabled the Black Death's rapid spread across Europe.

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:45am

How volcanic eruptions set off a chain of events that brought the Black Death to Europe

Clues contained in tree rings have identified mid-14th-century volcanic activity as the first domino to fall in a sequence that led to the devastation of the Black Death in Europe. 

Researchers  have used a combination of climate data and documentary evidence to paint the most complete picture to date of the "perfect storm" that led to the deaths of tens of millions of people, as well as profound demographic, economic, political, cultural and religious change.

Their evidence suggests that a volcanic eruption—or cluster of eruptions—around 1345 caused annual temperatures to drop for consecutive years due to the haze from volcanic ash and gases, which in turn caused crops to fail across the Mediterranean region. To avoid riots or starvation, Italian city states used their connections to trade with grain producers around the Black Sea.

This climate-driven change in long-distance trade routes helped avoid famine, but in addition to life-saving food, the ships were carrying the deadly bacterium that ultimately caused the Black Death, enabling the first and deadliest wave of the second plague pandemic to gain a foothold in Europe.

This is the first time that it has been possible to obtain high-quality natural and historical proxy data to draw a direct line between climate, agriculture, trade and the origins of the Black Death. The results are reported in the journal Communications Earth & Environment. 

The researchers say the "perfect storm" of climate, agricultural, societal and economic factors after 1345 that led to the Black Death can also be considered an early example of the consequences of globalization.

Although the coincidence of factors that contributed to the Black Death seems rare, the probability of zoonotic diseases emerging under climate change and translating into pandemics is likely to increase in a globalized world.

The researchers say that resilience to future pandemics requires a holistic approach to address a wide spectrum of health threats. Modern risk assessments should incorporate knowledge from historical examples of the interactions between climate, disease and society. 

Climate-driven changes in Mediterranean grain trade mitigated famine but introduced the Black Death to medieval Europe, Communications Earth & Environment (2025). DOI: 10.1038/s43247-025-02964-0

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:45am

Human hair grows through 'pulling' not pushing

Scientists have found that human hair growth does not grow by being pushed out of the root; it's actually pulled upward by a force associated with a hidden network of moving cells. The findings challenge decades of textbook biology and could reshape how researchers think about hair loss and regeneration.

Researchers  used advanced 3D live imaging to track individual cells within living human hair follicles kept alive in culture. The study, published in Nature Communications, shows that cells in the outer root sheath—a layer encasing the hair shaft—move in a spiral downward path within the same region from where the upward pulling force originates.

To test this, the researchers blocked cell division inside the follicle, expecting hair growth to stop. Instead, growth continued nearly unchanged. But when they interfere with actin—a protein that enables cells to contract and move—the hair growth rate dropped by more than 80%. 

Computer models confirmed that this pulling force, correlated with coordinated motion in the follicle's outer layers, was essential to match the observed speeds of hair movement. 

The researchers  used a novel imaging method allowing 3D time lapse microscopy in real-time. While static images provide mere isolated snapshots, 3D time-lapse microscopy is indispensable for truly unraveling the intricate, dynamic biological processes within the hair follicle, revealing crucial cellular kinetics, migratory patterns, and rate of cell divisions that are otherwise impossible to deduce from discrete observations. This approach made it possible to model the forces generated locally.

This reveals that hair growth is not driven only by cell division—instead, the outer root sheath actively pulls the hair upward. This new view of follicle mechanics opens fresh opportunities for studying hair disorders, testing drugs and advancing tissue engineering and regenerative medicine.

  The study also highlights the growing role of biophysics in biology, showing how mechanical forces at microscopic scale shape the organs we see every day. 

Nicolas Tissot et al, Mapping cell dynamics in human ex vivo hair follicles suggests pulling mechanism of hair growth, Nature Communications (2025). DOI: 10.1038/s41467-025-65143-x

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:44am

Single enzyme failure found to drive neuron loss in dementia 

 Loss of function in the enzyme glutathione peroxidase 4 (GPX4) disrupts neuronal protection against ferroptosis, leading to neuron death and early-onset dementia. A specific GPX4 mutation impairs its ability to neutralize lipid peroxides at the cell membrane, triggering neurodegeneration. Inhibiting ferroptosis can slow this process in experimental models.

Svenja M. Lorenz et al, A fin-loop-like structure in GPX4 underlies neuroprotection from ferroptosis, Cell (2025). DOI: 10.1016/j.cell.2025.11.014

https://medicalxpress.com/news/2025-12-enzyme-failure-neuron-loss-d...

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:43am

For the first time, researchers observe how influenza viruses infect living cells 

 A novel microscopy technique enabled real-time, high-resolution observation of influenza virus entry into living cells. Findings show that cells actively participate in viral uptake by recruiting clathrin proteins and forming membrane pockets, rather than being passive targets. This method offers valuable insights for antiviral drug development and can be applied to study other viruses.

Aiko Yoshida et al, Enhanced visualization of influenza A virus entry into living cells using virus-view atomic force microscopy, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2500660122

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:43am

Classical Indian dance inspires new ways to teach robots how to use their hands  

Analysis of Bharatanatyam dance gestures revealed a more versatile set of hand movement synergies than those found in natural grasps. These mudra-derived synergies enabled robots to replicate a wider range of hand motions, such as American Sign Language letters, more effectively. The findings support developing task-specific movement libraries for robotics and physical therapy applications.

Parthan Olikkal et al, Reconstructing hand gestures with synergies extracted from dance movements, Scientific Reports (2025). DOI: 10.1038/s41598-025-25563-7

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:42am

Most normal matter in the universe isn't found in planets, stars or galaxies

Only about 9% of the universe’s normal (baryonic) matter is found in stars and cold gas within galaxies, while 76% resides in the intergalactic medium and 15% in galaxy halos. This distribution matches Big Bang predictions, confirming that most normal matter exists as diffuse gas between galaxies, not in visible structures. Dark matter and dark energy remain the dominant, poorly understood components.

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:42am

So in his latest study, titled "Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation" and published in the Journal of Spacecraft and Rockets, researchers investigated ways to create commercial opportunities for space operators and debris remediators to clean up dangerous junk.

The study analyzed three possible scenarios of debris cleanup—controlled reentry back to Earth, uncontrolled reentry back to Earth, and recycling in space. All three methods would require a space debris remediation satellite - a vehicle designed to capture and remove space junk from orbit. 

In the uncontrolled re-entry scenario, the remediation service vehicle would grab the debris from the orbit path it flies in and bring it down to about 350 kilometers away from Earth. The piece of debris would continue orbiting around our planet until it entered the atmosphere and either burned or landed someplace.

It will either burn or drop somewhere on Earth, but we don't know where because it depends on the atmospheric drag it receives. This uncontrolled reentry method is the cheapest as the remediation vehicle doesn't have to fly long distances.

In the controlled reentry scenario, the remediation service vehicle would bring the debris much closer to Earth, down to about 50 kilometers.  Controlled reentry is more expensive because the servicer needs to bring the debris down closer to Earth and then fly up again to get the next piece of debris. That consumes more energy and more fuel than an uncontrolled reentry .

In the recycling scenario, the debris would be transported from its original orbit to a recycling center up in space. The transportation would require fuel, adding to the cost, but a lot of energy would also be saved by reusing aluminum, the metal commonly used in spacecraft, up in orbit rather than having to bring it up from Earth.

It takes about $1,500 per kilogram to launch anything from Earth to space.  . So if you don't have to launch from Earth, it's a benefit.

Space operators stand a lot to gain from debris removal. Their satellites can operate more safely and efficiently, so they save money on fuel and operations, since they don't have to make extra maneuvers to avoid collisions.

Asaad Abdul-Hamid et al, Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation, Journal of Spacecraft and Rockets (2025). DOI: 10.2514/1.a36465

https://phys.org/news/2025-12-space-debris-poses-threat-cleanup.htm...

part2

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:41am

Space debris poses growing threat, but new study suggests cleanup is feasible

High up in Earth's orbit, millions of human-made objects large and small are flying at speeds of over 15,000 miles per hour. The objects, which range from inactive satellites to fragments of equipment resulting from explosions or collisions of previously launched rockets, are space debris, colloquially referred to as space junk. Sometimes the objects collide with each other, breaking into even smaller pieces.

No matter the size, all of this debris poses a problem. Flying at high speeds caused by prior launches or explosions, they create danger for operational satellites and spacecraft, which are vital for the efficacy of modern technologies like GPS, digital communication and weather forecasting. At orbital speeds, even tiny fragments can cause significant damage to operational equipment, endangering future space missions and the people who would participate in them. 

Even if a tiny, five-millimeter object hits a solar panel or a solar array of a satellite, it could break it .  And we have over 100 million objects smaller than one centimeter in orbit. So if you want to avoid a collision, you have to maneuver your spacecraft, which takes up fuel and is costly. Additionally, we have humans on the International Space Station who sometimes must go outside the spacecraft where the space debris can hit them too. It's really dangerous.

Cleaning up space junk is technologically challenging and expensive. Furthermore, there are currently no incentives for countries or private companies to do so. Without binding international regulations or an enforceable "polluter pays" principle with consequences for noncompliance, the circumstances have led to a "cosmic free-for-all."

Part1

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:40am

Tattoos might put the immune system at risk

 Studies in mice suggest that the pigment used in tattoos accumulates in the lymph nodes and might affect immune responses. Researchers found that ink remained in the lymph nodes for months and had varying effects: it weakened the animals’ response to a COVID vaccine but increased the reaction to an influenza vaccine.

https://www.pnas.org/doi/10.1073/pnas.2510392122

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