Tag Archives: interaction

Animal Study Reveals New Insights into the Interaction Between Sleep and Growth Hormone Regulation

Posted on by
Reply

Researchers from the University of California, Berkeley and Stanford University have investigated the brain circuits that regulate the release of growth hormone during sleep. Their findings reveal new feedback mechanisms that keep growth hormone levels finely tuned. This discovery could lead to advancements in treating individuals with sleep disorders associated with metabolic issues like diabetes, as well as degenerative diseases such as Parkinson’s and Alzheimer’s.

Sleep is known to promote tissue growth and regulate metabolism by partially promoting growth hormone (GH) release, but the underlying circuit mechanism is unknown. Ding et al. show how GH release, which is enhanced in both rapid eye movement (REM) and non-REM (NREM) sleep, is regulated by sleep-wake-dependent activities of distinct hypothalamic neurons that express GH release hormone (GHRH) and somatostatin (SST). Arcuate nuclei SST neurons inhibit GH release by targeting nearby GHRH neurons that stimulate GH release, while periencephalic SST neurons project onto the median ridge to inhibit GH release. GH release is associated with significant surges of both GHRH and SST activity during REM sleep, while NREM sleep sees moderate increases in GHRH and reductions in SST activity. Furthermore, Ding et al. identified negative feedback pathways where GH increases the excitability of locus ceruleus neurons, leading to increased arousal. Image credit: Ding et al, doi: 10.1016/j.cell.2025.05.039.

“We have gained significant insights into this area,” said Xinlu Ding, a postdoctoral researcher at the University of California, Berkeley.

“We directly recorded the neural activity of mice to understand the underlying processes.”

“Our findings provide a foundational circuit to explore various treatment options moving forward.”

Neurons that manage growth hormone release during the sleep-wake cycle—specifically growth hormone-releasing hormone (GHRH) neurons and two types of somatostatin neurons—are located deep within the hypothalamus, an ancient brain region present in all mammals.

Once released, growth hormone enhances the activity of locus coeruleus neurons, a brainstem region involved in arousal, attention, cognition, and curiosity.

Dysregulation of locus coeruleus neurons is linked to numerous psychiatric and neurological disorders.

“Understanding the neural circuits involved in growth hormone release could ultimately lead to new hormone therapies aimed at enhancing sleep quality and restoring normal growth hormone levels,” explained Daniel Silverman from the University of California, Berkeley.

“Several experimental gene therapies have been developed that target specific cell types.”

“This circuit could serve as a new approach to modulate the excitability of the locus coeruleus, which has not been effectively targeted before.”

The researchers investigated neuroendocrine circuits by implanting electrodes into the mouse brain and measuring activity changes triggered by light stimulation of hypothalamic neurons.

Mice have short sleep bouts (lasting several minutes at a time) throughout day and night, providing ample opportunities to study fluctuations in growth hormone during the sleep-wake cycle.

Utilizing advanced circuit mapping techniques, researchers found that the two peptide hormones (GHRH and somatostatin) regulating growth hormone release operate differently during REM and non-REM sleep.

Both somatostatin and GHRH promote growth hormone release during REM sleep; however, somatostatin decreases and GHRH sees only moderate increases during non-REM sleep, which still results in growth hormone release.

Growth hormone release regulates locus coeruleus activity through a feedback mechanism, creating a homeostatic balance.

During sleep, growth hormone accumulates at a gradual pace, stimulating the locus coeruleus and fostering arousal, according to the new findings.

However, excessive activation of the locus coeruleus can paradoxically lead to drowsiness.

“This indicates that sleep and growth hormone form a delicate balance. Insufficient sleep diminishes growth hormone release, while excessive growth hormone may drive the brain toward wakefulness,” Dr. Silverman noted.

“Sleep facilitates growth hormone release, which in turn regulates arousal. This equilibrium is crucial for growth, repair, and metabolic health.”

Growth hormone functions partially through the locus coeruleus, influencing overall brain alertness during wakefulness, emphasizing the importance of maintaining proper balance for cognitive function and attention.

“Growth hormone is pivotal not only for muscle and bone development and reducing fat tissue, but it also offers cognitive benefits and can elevate overall arousal levels upon waking,” stated Dr. Ding.

study Published in the journal Cell.

____

Xinlu Ding et al. 2025. Neuroendocrine circuits for sleep-dependent growth hormone release. Cell 188 (18): 4968-4979; doi: 10.1016/j.cell.2025.05.039

Source: www.sci.news

Physicists Investigate Light’s Interaction with Quantum Vacuums

Posted on by
Reply

Researchers have successfully conducted the first real-time 3D simulation demonstrating how a powerful laser beam alters the quantum vacuum. Remarkably, these simulations reflect the unusual phenomena anticipated by quantum physics, known as vacuum four-wave mixing. This principle suggests that the combined electromagnetic fields of three laser pulses can polarize a virtual electron-positron pair within a vacuum, resulting in photons bouncing toward one another as if they were billiard balls.

Illustration of photon photon scattering in a laboratory: Two green petawatt laser beams collide in focus with a third red beam to polarize the quantum vacuum. This allows the generation of a fourth blue laser beam in a unique direction and color, conserving momentum and energy. Image credit: Zixin (Lily) Zhang.

“This is not merely a matter of academic interest. It represents a significant advance toward experimental validation of quantum effects, which have largely remained theoretical,” remarks Professor Peter Norries from Oxford University.

The simulation was executed using an enhanced version of Osiris, a simulation software that models interactions between laser beams and various materials or plasmas.

“We are doctoral students at Oxford University,” shared Zixin (Lily) Zhang.

“By applying the model to a three-beam scattering experiment, we were able to capture a comprehensive spectrum of quantum signatures, along with detailed insights into the interaction region and the principal time scale.”

“We’ve rigorously benchmarked the simulation, enabling our focus to shift to more intricate, exploratory scenarios, like exotic laser beam structures and dynamic focus pulses.”

Crucially, these models furnish the specifics that experimentalists depend on to design accurate real-world tests, encompassing realistic laser configurations and pulse timing.

The simulations also uncover new insights into how these interactions develop in real-time and how subtle asymmetries in beam geometry can influence the outcomes.

According to the team, this tool not only aids in planning future high-energy laser experiments but also assists in the search for evidence of virtual particles, such as axes and millicharged particles, or potential dark matter candidates.

“The broader planned experiments at state-of-the-art laser facilities will greatly benefit from the new computational methods implemented in Osiris,” noted Professor Lewis Silva, a physicist at the Technico Institute in Lisbon and Oxford.

“The integration of ultra-intense lasers, advanced detection techniques, cutting-edge analysis, and numerical modeling lays the groundwork for a new era of laser-material interactions, opening new avenues for fundamental physics.”

The team’s paper was published today in the journal Communication Physics.

____

Z. Chan et al. 2025. Computational modeling of semi-real-world quantum vacuums in 3D. Commun Phys 8, 224; doi:10.1038/s42005-025-02128-8

Source: www.sci.news

The Interaction of Fast-Moving Electrons and Photons Drives X-Ray Emission in Blazar Jets

Posted on by
Reply

A recent study utilized NASA’s IXPE (Imaging X-ray Polarized Explorer) to analyze a highly relativistic jet originating from the Blazar Bl Lacertae, a supermassive black hole surrounded by luminous discs.

This artist’s rendering illustrates the core area of Blazar Bl Lacertae, featuring an ultra-massive black hole surrounded by bright discs and Earth-directed jets. Image credit: NASA/Pablo Garcia.

Astrophysicists elucidated a highly relativistic jet, proposing two competing theories regarding an X-ray component made up of protons and electrons.

Each theory presents a distinct signature in the polarization characteristics of the X-ray light.

Polarized light signifies the average direction of the electromagnetic waves comprising light.

When X-rays in a black hole’s jets are highly polarized, it indicates production from protons that circulate within the magnetic field of the jet or protons interacting with the jet’s photons.

Conversely, low polarization in X-rays implies that the generation of X-rays occurs through electron-photon interactions.

The IXPE is the sole satellite capable of making such polarization measurements.

“This was one of the greatest mysteries involving supermassive black hole jets,” remarks Dr. Ivan Agdo, an astronomer at Astrophicidae Athtrophicidae and Andocia-CSIC.

“Thanks to numerous supporting ground telescopes, IXPE equipped us with the necessary tools to ultimately resolve this issue.”

Astronomers concluded that electrons are likely the source, through a process known as Compton scattering.

This phenomenon, also referred to as the Compton effect, occurs when photons lose or gain energy through interactions with charged particles (primarily electrons).

Within the jets of a supermassive black hole, electrons move at speeds approaching that of light.

IXPE enabled researchers to determine that, in Blazar jets, electrons possess enough energy to scatter infrared photons into the X-ray spectrum.

Bl Lacertae, one of the earliest discovered Blazars, was initially thought to be a kind of star in the Lacerta constellation.

IXPE monitored Bl Lacertae for seven days in November 2023, in conjunction with several ground-based telescopes also measuring optical and radio polarization.

Interestingly, during the X-ray polarization observations, Bl Lacertae’s light polarization peaked at 47.5%.

“This marks not only the most polarized BL Lacertae has been in the past 30 years, but indeed the highest ever recorded,” states Dr. Ioannis Riodakis, an astrophysicist at the Institute of Astrophysics.

Researchers noted that X-rays are significantly less polarized than optical light.

They were unable to detect strong polarized signals and ascertained that the X-rays could not exceed 7.6% polarization.

This finding confirms that electron interactions with photons via the Compton effect must account for the X-ray emissions.

“The fact that optical polarization is considerably higher than that of X-rays can only be explained by Compton scattering,” he added.

“IXPE has solved yet another mystery surrounding black holes,” claimed Dr. Enrico Costa, an astrophysicist associated with the planet spaziali of astituto to astituto to n diastrofísica.

“IXPE’s polarized X-ray capabilities have unraveled several long-standing mysteries, which is a significant achievement.

“In other instances, IXPE’s results challenged previously held beliefs, opening up new questions, but that’s the essence of science, and certainly IXPE excels in its scientific contributions.”

Survey results will be published in Astrophysics Journal Letter.

____

Ivan Agd et al. 2025. The height of X-ray and X-ray polarization reveals Compton scattering of BL Lacertae jets. apjl in press; doi: 10.3847/2041-8213/ADC572

Source: www.sci.news

Skype and Zoom Answered the Call and Transformed Human Interaction: John Norton’s Perspective

Posted on by
Reply

sO Microsoft It's decided An internet telephony company purchased it for $8.5 billion (£6.6 billion) in 2011 to end Skype. Millions of unfortunate users flock to the Microsoft Team, a virtual camp with a brain-dead aesthetic that even Zoom looks cool. This unforeseen situation has been telegraphed for quite some time, but even so, Skype is an astounding venture, and its ending mise is brought as a shock as it closes an interesting chain chapter in technological history.

The Internet has been around for a long time than most people notice. It dates back to the 1960s and back to the creation of Alpanet, a military computer network that emerged after the US had the “Sputnik moment.” It's a terrible perception that the Soviet Union appears to be moving forward with technology interests. The Internet design used today, the successor to Arpanet, began in the early 1970s and was first switched in January 1983.

From the start, the network designers decided to avoid limitations on previous communication systems, particularly voice-optimized analog telephone networks. This was owned by companies that were hopeless about digital signals and resisted innovation that they themselves had not been generating. Therefore, new networks have no owners or are not optimized for a particular medium, making them more tolerant than previous networks. Anyone can access it and create a service run as long as the computer meets the network's protocols.

As a result, we are an explosion of creativity that we live together today. What the Internet designers built was what scholars later called “an architecture for unauthorized innovation.” Or, in another way, global Platform for gushing surprises.

Created by Tim Berners-Lee in the late 1980s, the World Wide Web was one of those surprises. However, there was also something called VoIP (Voice over Internet Protocol). Speeches can be digitized (one and zero) and placed in data packets that can be sent over the Internet. And after reaching the destination it was converted to audio. Results: Free telephony anywhere in the world!

Skype was the first company to bring this magic to ordinary consumers. Founded in 2003 by Janus Friis (A Dane) and Niklas Zennström (Swedish) and headquartered in Luxembourg. However, the software that was equipped with it was written by three Estonians who also wrote peer-to-peer file sharing software. In 2005, eBay bought it for $2.6 billion (£2 billion). By 2006 there were 100 million registered users, and by 2009 it had added about 380,000 new users every day, generating approximately $740 million (£575 million) in annual revenue. So, Skype was the first European company to reach US-level size.

At that point, something inevitable happened: in 2011 Skype was purchased by Microsoft and absorbed by Tech Colossus' Maw. Many observers, including this columnist, wondered what Microsoft thought was doing with the new toy. Last week's news suggests that the company never understood it. Either way, after the pandemic arrived in 2020 and people started working from home, it was clear that Microsoft needed to have something to drive away the threat posed by Zoom. Skype may have probably become the core of that response, but instead the decision was made to place all the energy to make the team a Behemoth answer to remote working. Since then, Skype has been surplus to the requirements and dies have been cast.

But before it disappears, it is worth remembering that it was on the scene 20 years ago. Today, most people don't know how close telephony is, in the analog era, is, closed and depressing. It was an industry run by either a complacent, unresponsive, dominant monopoly (USA AT&T) or governmental institutions (UK GPOs). It may take several months to install a phone in your home. The phones were expensive and international calls were actively prohibited.

I grew up in the country (Ireland) with a huge diaspora at a time when calls from the US only meant one family death. If immigrants were in touch with people returning home, it was just letters and perhaps a strange parcel. It's not a phone call. In rural Ireland, their families will occasionally wake up the night before their sons and daughters leave for America or Australia.

And now? The VoIP technology that Skype brings to people's lives is commoditized. Social media platforms like WhatsApp and Signal offer unlimited and free audio (and video) connections with friends, family and colleagues around the world. Calls that were once bankrupt are made every day. Microsoft may not have thought that Skype would ultimately help. But the rest of us certainly did.

What I've read

3 Market Economy
Dave Karpf's A sharp essay Identify the three types of money behind the power of Silicon Valley.

I will take home sovereignty
an An insightful editorial in Norma Why the current and the 47th President is acting like the 25th by Nathan Gardells.

A story of battle
David Allen Green is in the offshore earthquake control collision Foresightful analysis in Financial Times.

Source: www.theguardian.com

Research shows that Homo sapiens and Neanderthals had 200,000 years of interaction

Posted on by
Reply

A recent study indicates that multiple instances of gene flow occurring between 250,000 and 200,000 years ago impacted the genomes and biology of both modern humans and Neanderthals, who are believed to share 2.5 to 3.7 percent of human ancestry.

Li othersIt provides insight into the history of modern-human Neanderthal admixture, shows that gene flow has significantly influenced patterns of genomic variation in modern and Neanderthals, and suggests that taking into account human-derived sequences in Neanderthals allows for more precise inferences about admixture and its consequences in both Neanderthals and modern humans. Image courtesy of the Neanderthal Museum.

“For the first time, geneticists have identified multiple instances of interbreeding between modern humans and Neanderthals,” stated Professor Li Ming from Southeast University.

“It is now evident that throughout most of human history, there was interaction between modern humans and Neanderthals,” added Professor Joshua Akey from Princeton University.

“Our direct ancestors, hominins, diverged from the Neanderthal lineage approximately 600,000 years ago and acquired modern physical characteristics around 250,000 years ago.”

“Subsequently, modern humans continued to engage with Neanderthals for around 200,000 years until the extinction of Neanderthals.”

The researchers utilized the genomes of 2,000 modern humans, three Neanderthals, and one Denisovan to track gene flow between human populations over the past 250,000 years.

They employed a genetic tool called IBDmix, developed several years ago, which utilizes machine learning techniques for sequencing genomes.

Previously, scientists relied on comparing the human genome to reference populations of modern individuals with minimal or no Neanderthal or Denisovan DNA.

The study authors discovered traces of Neanderthal DNA even in populations residing thousands of miles south of Neanderthal caves, suggesting that the DNA might have been transmitted southward by travelers or their descendants.

Using IBDmix, they identified a first contact wave around 200,000-250,000 years ago, a second contact wave around 100,000-120,000 years ago, and a peak contact wave around 50,000-60,000 years ago, deviating from previous genetic data.

“Most genetic data indicates that modern humans originated in Africa 250,000 years ago, persisted there for another 200,000 years, and only around 50,000 years ago dispersed from Africa to populate other regions as humans,” said Prof Akey.

“Our model suggests that there wasn’t a prolonged period of stasis, but soon after the emergence of modern humans, we migrated out of Africa and eventually returned.”

“To me, the narrative revolves around dispersal, highlighting that modern humans have been more mobile than previously assumed, encountering Neanderthals and Denisovans,” added Prof Akey.

This portrayal of migrating humans aligns with archaeological and paleoanthropological evidence indicating cultural and tool exchanges among human populations.

A crucial insight was to search for modern human DNA in the Neanderthal genome, rather than vice versa.

“While much genetic research in the past decade focused on how interbreeding with Neanderthals influenced the evolution and phenotype of modern humans, these questions also hold importance and interest in the opposite direction,” noted Professor Akey.

They realized that the descendants of the initial interbreeding event between Neanderthals and modern humans likely stayed with the Neanderthals and thus left no genetic trace in modern humans.

“By incorporating Neanderthal elements into genetic studies, we can analyze these early migrations in a new light,” Prof Akey mentioned.

The final revelation was that the Neanderthal population was smaller than previously estimated.

Traditional genetic modeling used diversity as an indicator of population size: greater genetic diversity implied a larger population.

However, using IBDmix, the team showed that most diversity came from DNA sequences originating from a larger modern human population, leading to a reduction in the effective Neanderthal population from around 3,400 breeding individuals to approximately 2,400.

Collectively, these new findings provide insights into the disappearance of Neanderthals from the record roughly 30,000 years ago.

“I prefer not to use the term ‘extinction’ because I believe Neanderthals were mostly assimilated,” mentioned Prof Akey.

It is theorized that the Neanderthal population gradually dwindled, with the last survivors merging into modern human communities.

“The assimilation model was first proposed in 1989 by anthropologist Fred Smith from Illinois State University, and our results offer compelling genetic evidence supporting Fred’s hypothesis,” Prof Akey stated.

“Neanderthals likely faced prolonged near-extinction.”

“Our estimates suggest that even a slight decrease of 10 to 20 percent in the population size would have a significant impact on an already vulnerable population,” Prof Akey added.

“Modern humans can be likened to waves gradually eroding the shoreline, eventually overwhelming Neanderthals demographically and integrating them into the modern human population.”

Read the full research findings published in the journal Science.

_____

Li-Ming Lee others2024. Recurrent gene flow between Neanderthals and modern humans over the past 200,000 years. Science 385(6705); doi:10.1126/science.adi1768

Source: www.sci.news