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Comment by Dr. Krishna Kumari Challa yesterday

But we can't explain everything, the authors of this study contends. There are anomalies that don't seem to fit the so-called "Standard Model" of the universe.

That the visible and hidden sectors are mutually isolated is a misconception, they say, based on an assumption "that the visible and the hidden sectors evolved independently of each other." The new work wants to turn that assumption on its head.

In a paper published in Physical Review D, "Big Bang Initial Conditions and Self-Interacting Hidden Dark Matter, they want to ask what they call "the more important question: How do we know that they evolved independently?"

To test this assumption, Nath and his team "introduced some feeble interactions" between the two sectors into their models of the Big Bang. These meager interactions wouldn't be enough to affect the outcome of, say, particle accelerator experiments, "but we wanted to see what the effects would be on the visible sector as a whole," Nath says, "from the time of the Big Bang to the current time."
Even with minimal interactions between the two sectors, Nath and his team discovered that dark matter's influence on the visible matter we're made of could have a major impact on observable phenomena.

The Hubble expansion—which says, in the simplest terms, that galaxies are moving away from one another, and thus that the universe is expanding—for instance, contains a "quite serious" differential between what the Standard Model predicts and what has been observed. Nath's models partially account for this difference.

Comment by Dr. Krishna Kumari Challa yesterday

New models of Big Bang show that visible universe and invisible dark matter co-evolved

Physicists have long theorized that our universe may not be limited to what we can see. By observing gravitational forces on other galaxies, they've hypothesized the existence of "dark matter," which would be invisible to conventional forms of observation.

95% of the universe is dark, is invisible to the eye. 

However, we know that the dark universe is there by its gravitational pull on stars. Other than its gravity, dark matter has never seemed to have much effect on the visible universe.

Yet the relationship between these visible and invisible domains, especially as the universe first formed, has remained an open question.

Now, physicists say that there is mounting evidence that these two supposedly distinct realms actually co-evolved.

Through a series of computer models, physicists have discovered that the visible and the hidden sectors, as they call them, likely co-evolved in the moments after the Big Bang, with profound repercussions for how the universe developed thereafter.

They say there was a time when some physicists effectively wrote off this hidden sector, as they can explain most of what happens within the visible—that is, if our models can accurately portray what we can see happening around us, why bother trying to measure something that has no discernible effect?

The question is, what's the influence of the hidden sector on the visible sector?"  "But what do we care? We can explain everything."

Part 1

Comment by Dr. Krishna Kumari Challa yesterday

The researchers now plan to use their electron videography technique to study other types of membrane proteins and other classes of molecules and nanomaterials.

 John W. Smith et al, Electron videography of a lipid–protein tango, Science Advances (2024). DOI: 10.1126/sciadv.adk0217

Part 4

Comment by Dr. Krishna Kumari Challa yesterday

The researchers achieved videography by combining a novel water-based transmission electron microscopy method with detailed, atom-level computational modeling. The water-based technique involves encapsulating nanometer-scale droplets in graphene so they can withstand the vacuum in which the microscope operates. Comparing the resulting video data to molecular models, which show how things should move based on the laws of physics, helps the researchers not only interpret but also validate their experimental data.
Currently, this is really the only experimental way to film this kind of motion over time. Life is in liquid, and it's in motion. Scientists 're trying to get to the finest details of that connection in an experimental way.
For the new study—the first published demonstration of the electron videography technique—the researchers examined nanoscale discs of lipid membranes and how they interacted with proteins normally found on the surface of or embedded in cell membranes.
Part 3

Comment by Dr. Krishna Kumari Challa yesterday

Electron microscopy techniques image at the molecular or atomic scale, yielding detailed, nanometer-scale pictures. However, they often rely on samples that have been frozen or fixed in place, leaving scientists to try to infer how molecules move and interact—like trying to map the choreography of a dance sequence from a single frame of film.

Usually, researchers have to crystalize or freeze a protein, which poses challenges in capturing high-resolution images of flexible proteins. Alternately, some techniques use a molecular tag that they track, rather than watching the protein itself. In this study they are seeing the protein as it is, behaving how it does in a liquid environment, and seeing how lipids and proteins interact with each other.

Part 2

Comment by Dr. Krishna Kumari Challa yesterday

Electron videography captures moving dance between proteins and lipids

In a first demonstration of "electron videography," researchers have captured a microscopic moving picture of the delicate dance between proteins and lipids found in cell membranes. The technique can be used to study the dynamics of other biomolecules, breaking free of constraints that have limited microscopy to still images of fixed molecules.

Scientists are now  are going beyond taking single snapshots, which gives structure but not dynamics, to continually recording the molecules in water, their native state.

They can really see how proteins change their configuration and, in this case, how the whole protein-lipid self-assembled structure fluctuates over time.

The researchers reported their technique and findings in the journal Science Advances.

Part 1

Comment by Dr. Krishna Kumari Challa yesterday

The researchers also described other instances over a period of 19 months of observation when fosas appeared to stalk lemurs but were unsuccessful in bringing one down as food.

The impact of predation—combined with low reproductive rates and potentially high inbreeding of the lemur population of Betampona—could affect the survival of this species at this site, researchers said.

These most recent observations of fosa attacks are especially troubling, as the observation of predation attacks, especially by the elusive fosa, are very rare.

"It leads to questions of why the fosa are so bold to predate on lemurs in front of humans, and whether the fosa leave Betampona to hunt elsewhere and then return, or whether they are targeting the lemurs within the reserve,"the researchers say. "It is an incredible scenario in which you have a vulnerable species potentially over-predating on several critically endangered species."

G. Bonadonna et al, Response of diademed sifaka (Propithecus diadema) to fosa (Cryptoprocta ferox) predation in the Betampona Strict Nature Reserve, Madagascar, Ecology and Evolution (2024). DOI: 10.1002/ece3.11248

Part 2

Comment by Dr. Krishna Kumari Challa yesterday

When one vulnerable species stalks another

What can be done when one threatened animal kills another? Scientists studying critically endangered lemurs in Madagascar confronted this difficult reality when they witnessed attacks on lemurs by another vulnerable species, a carnivore called a fosa.

This dynamic can be particularly complex when the predation occurs in an isolated or poor-quality habitat, according to research by scientists  in Madagascar.

In the new paper published in Ecology and Evolution, researchers describe how they were observing small groups of critically endangered diademed sifaka lemurs (Propithecus diadema) at Betampona Strict Nature Reserve when the predator struck.

"We were conducting our daily behavioural observations when we came across a very unusual sight—a predation attempt by a fosa, which is the biggest predator in Madagascar", the researchers depicted the story.

"What we saw was very rare," they wrote in their paper. "There are other small carnivores in Madagascar, but they are not big enough to be able to prey upon an adult diademed sifaka because they are among the biggest lemurs. There are not so many predators that could actually get them."

With slender bodies and long tails, fosas (or fossas, Crytoprocta ferox) have many cat-like features. They are great climbers and are sometimes compared to small cougars, though they are actually part of the weasel family.

The fosa is categorized as vulnerable by the International Union for Conservation of Nature and Natural Resources, and is at risk of extinction, as are almost all of its lemur prey. Fosas also eat other small animals such as birds and rodents.

But they're rarely caught in the act. Fosas are stealthy hunters. Researchers have mostly determined what fosas eat by examining bones and other evidence left behind in scat.

"We noticed that a female diademed sifaka that we were following after the first attack didn't run away very far," they said. "Instead she stayed still and remained vigilant, looking at the fosa."

 also documented the later discovery of the remains of another diademed sifaka, presumed to have been killed by a fosa because of the condition of the remains and because of the way that branches had been broken in the area. Signs indicated a struggle in the trees.

Part 1

Comment by Dr. Krishna Kumari Challa yesterday

In their new study, the scientists look at the dense environment of dusty disks, from which a new solar system with a star and planets emerges eventually. Such disks form when clouds suddenly collapse under the force of gravity. In this environment, water molecules are much more prevalent—forming ice on the surface of any growing agglomerates of particles that could inhibit the reactions that form peptides.

By emulating the reactions likely to occur in the interstellar medium in the laboratory, the study shows that, although the formation of peptides is slightly diminished, it is not prevented. Instead, as rocks and dust combine to form larger bodies such as asteroids and comets, these bodies heat up and allow for liquids to form. This boosts peptide formation in these liquids, and there's a natural selection of further reactions resulting in even more complex organic molecules. These processes would have occurred during the formation of our own solar system.

Many of the building blocks of life such as amino acids, lipids and sugars can form in the space environment. Many have been detected in meteorites.

Because peptide formation is more efficient in space than on Earth, and because they can accumulate in comets, their impacts on the early Earth might have delivered loads that boosted the steps towards the origin of life on Earth.
So what does all this mean for our chances of finding alien life? Well, the building blocks for life are available throughout the universe. How specific the conditions need to be to enable them to self-assemble into living organisms is still an open question. Once we know that, we'll have a good idea of how widespread, or not, life might be.

Serge A. Krasnokutski et al, Formation of extraterrestrial peptides and their derivatives, Science Advances (2024). DOI: 10.1126/sciadv.adj7179

Part 3

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Comment by Dr. Krishna Kumari Challa yesterday

DNA, or deoxyribonucleic acid, comprises two long strands forming a double helix structure. Each strand is composed of smaller molecules called nucleotides. Every nucleotide contains three components: a sugar molecule (deoxyribose in DNA), a phosphate group, and a nitrogenous base. There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair specifically (A with T, C with G) to form the rungs of the double helix ladder, with the sugar and phosphate groups forming the backbone of the DNA molecule.

Peptides are an assemblage of amino acids in a short chain-like structure. Peptides can be made up of as little as two amino acids, but also range to hundreds of amino acids.

The assemblage of amino acids into peptides is an important step because peptides provide functions such as "catalyzing," or enhancing, reactions that are important to maintaining life. They are also candidate molecules that could have been further assembled into early versions of membranes, confining functional molecules in cell-like structures.

However, despite their potentially important role in the origin of life, it was not so straightforward for peptides to form spontaneously under the environmental conditions on the early Earth. In fact, the scientists behind the current study had previously shown that the cold conditions of space are actually more favourable to the formation of peptides.

In the very low density of clouds of molecules and dust particles in a part of space called the interstellar medium, single atoms of carbon can stick to the surface of dust grains together with carbon monoxide and ammonia molecules. They then react to form amino acid-like molecules. When such a cloud becomes denser and dust particles also start to stick together, these molecules can assemble into peptides.
Part 2

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