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Comment by Dr. Krishna Kumari Challa on November 28, 2020 at 6:54am

Understanding Skull Base Tumors

https://www.uhhospitals.org/health-information/health-and-wellness-....

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Periodic table: scientists propose new way of ordering the elements

https://theconversation.com/periodic-table-scientists-propose-new-w...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 11:44am

Miniscule robots of metal and plastic

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 11:42am

**   Pregnancy stress may shape baby brain

Stress levels in mothers – measured by a hormone linked to anxiety and other health problems – is related to changes in areas of the infant brain associated with emotional development, the study suggests. Doctors say the findings highlight the urgent need for women to be better supported with their mental and physical health before and during pregnancy, and could help them spot mums and babies who need help. The experts add that pregnant women who feel stressed or unwell should seek help from their midwife or consultant and that with support, most health issues can be well managed in pregnancy. Maternal stress is known to influence the development of the child’s behaviour and ability to regulate its emotions as it grows. This is usually measured by questionnaires, which are not always reliable. The new study is the first time that scientists have used an objective measure – levels of the hormone cortisol – in the mother to study links with baby brain development.

https://researchnews.cc/news/3791/Pregnancy-stress-may-shape-baby-b...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 11:29am

Moth wings sport acoustic camouflage

Moths draped in stealth acoustic cloak evade bat sonar

Moths can hide from the sonar of feeding bats using their acoustically camouflaged wings. Their evolved stealth adaptation is the result of an array of scales attached to their wing membranes that absorb ultrasound frequencies emitted by hunting bats, and are the first acoustic metamaterials found in nature.

A University of Bristol team discovered that sound waves from bats that hit the fork-shaped scales found on two species of moth cause them to bend and twist, dissipating the energy. ‘Less sound is reflected back to the bat, and the moth thereby disappears or partially disappears from the bat’s sonar screen

Z Shen et al, Proc. Natl. Acad. Sci. USA, 2018, 115, 12200 (DOI: 10.1073/pnas.1810025115)

https://www.chemistryworld.com/news/moths-draped-in-stealth-acousti...

Scales on the wings of moths form acoustic camouflage that hides the insects from the sonar of bats. Researchers examined the Chinese tusar moth (Antheraea pernyi) and Dactyloceras lucina, a large African moth. These species have no ears to hear approaching predators. Instead, they defend themselves using a dense array of tiny, thin scales that each resonate at a particular frequency. Together, the scales absorb at least three octaves of sound — the first known natural acoustic metamaterial. The intricate arrangement and structure of the scales could inspire ultrathin sound-absorbing materials: think sound-absorbing wallpaper instead of panels, say researchers.

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 10:59am

**Climate change is making autumn leaves change colour earlier – here’s why

research shows that deciduous trees can only absorb a set amount of carbon each year and once that limit is reached, no more can be absorbed. At that point, leaves begin to change colour. This limit is set by the availability of nutrients, particularly nitrogen, and the physical structure of the plant itself, particularly the inner vessels which move water and dissolved nutrients around. Nitrogen is a key nutrient which plants need in order to grow, and it’s often the amount of available nitrogen that limits total growth. This is why farmers and gardeners use nitrogen fertilisers, to overcome this limitation.

Together, these constraints mean that carbon uptake during the growing season is a self-regulating mechanism in trees and herbaceous plants. Only so much carbon can be taken up.

In a world with increasing levels of carbon in the atmosphere, these new findings imply that warmer weather and longer growing seasons will not allow temperate deciduous trees to take up more carbon dioxide. The study’s predictive model suggests that by 2100, when tree growing seasons are expected to be between 22 and 34 days longer, leaves will fall from trees between three and six days earlier than they do now.

with the prospect of some trees losing their leaves earlier and others losing them at the time they do now, there might be the prospect of prolonged autumnal colours – and more time for us to kick through the leaves.

https://theconversation.com/climate-change-is-making-autumn-leaves-...

https://researchnews.cc/news/3819/Which-factors-trigger-leaf-die-of...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 10:15am

High blood pressure in midlife is linked to increased brain damage in later life

Higher than normal blood pressure is linked to more extensive brain damage in the elderly, according to a new study published.

In particular, the study found that there was a strong association between diastolic blood pressure (the blood pressure between heart beats) before the age of 50 and brain damage in later life, even if the diastolic blood pressure was within what is normally considered to be a healthy range.

The findings come from a study of 37,041 participants enrolled in UK Biobank, a large group of people recruited from the general population aged between 40 and 69 years, and for whom medical information, including MRI brain scans was available.

Karolina Agnieszka Wartolowska et al, Midlife blood pressure is associated with the severity of white matter hyperintensities: analysis of the UK Biobank cohort study, European Heart Journal (2020). DOI: 10.1093/eurheartj/ehaa756

https://medicalxpress.com/news/2020-11-high-blood-pressure-midlife-...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 10:10am

New Hubble data explains missing dark matter

New data from the NASA/ESA Hubble Space Telescope provides further evidence for tidal disruption in the galaxy NGC 1052-DF4. This result explains a previous finding that this galaxy is missing most of its dark matter. By studying the galaxy's light and globular cluster distribution, astronomers have concluded that the gravity forces of the neighbouring galaxy NGC 1035 stripped the dark matter from NGC 1052-DF4 and are now tearing the galaxy apart.

The galaxy "missing dark matter" NGC1052-DF4 is undergoing tidal disruption arXiv:2010.09719 [astro-ph.GA] arxiv.org/abs/2010.09719

https://phys.org/news/2020-11-hubble-dark.html?utm_source=nwletter&...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 10:07am

Ancient Earth had a thick, toxic atmosphere like Venus—until it cooled off and became liveable

A rocky planet like Earth is born through a process called "accretion", in which initially small particles clump together under the pull of gravity to form larger and larger bodies. The smaller bodies, called "planetesimals", look like asteroids, and the next size up are "planetary embryos". There may have been many planetary embryos in the early Solar System, but the only one that still survives is Mars, which is not a fully fledged planet like Earth or Venus.

The late stages of accretion involve giant impacts that release enormous amounts of energy. We think the last impact in Earth's accretion involved a Mars-sized embryo hitting the growing Earth, spinning off our Moon, and melting most or all of what was left.

The impact would have left Earth covered in a global sea of molten rock called a "magma ocean". The magma ocean would have leaked hydrogen, carbon, oxygen and nitrogen gases, to form Earth's first atmosphere.

This ratio of CO₂ to N₂ is strikingly like the present atmosphere on Venus. So why did Venus, but not Earth, retain the hellishly hot and toxic environment we observe today?

The answer is that Venus was too close to the Sun. It simply never cooled down enough to form water oceans. Instead, the H₂O in the atmosphere stayed as water vapour and was slowly but inexorably lost to space.

On the early Earth, the water oceans instead slowly but steadily drew down CO₂ from the atmosphere by reaction with rock – a reaction known to science for the past 70 years as the “Urey reaction”, after the Nobel prizewinner who discovered it – and reducing atmospheric pressure to what we observe today.

So, although both planets started out almost identically, it is their different distances from the Sun that put them on divergent paths. Earth became more conducive to life while Venus became increasingly inhospitable.

Paolo A. Sossi et al. Redox state of Earth's magma ocean and its Venus-like early atmosphere, Science Advances (2020). DOI: 10.1126/sciadv.abd1387

https://theconversation.com/ancient-earth-had-a-thick-toxic-atmosph...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 10:00am

Foreign vs. own DNA: How an innate immune sensor tells friend from foe

How do molecules involved in activating our immune system discriminate between our own DNA and foreign pathogens? Researchers deciphered the structural and functional basis of a DNA-sensing molecule when it comes in contact with the cell's own DNA, providing crucial insights into the recognition of self vs. non-self DNA.

DNA within our cells is compacted and stored in the nucleus in the form of chromatin (DNA wraped around histone proteins, forming nucleosomes, the basic unit of chromatin). DNA found outside the nucleus, in the cytoplasm, is an important signal that triggers immune responses indicating the presence of an intracellular pathogen or a potentially cancerous cell. DNA sensing is carried out by cGAS, an enzyme responsible for recognizing and binding naked DNA. When activated, cGAS synthesizes cyclic GMP-AMP, which in turn initiates the body's so-called "innate" immune system—the first-line-of-defense part of our immune system.

Until now, cGAS was thought to function predominantly in the cytoplasm, detecting foreign, non-self, DNA such as viruses. But recent studies suggested that cGAS is also present inside the nucleus. This was puzzling given the possibility that the enzyme is activated by its own DNA triggering an unwanted inflammatory response against its own DNA. Intrigued by this observation, researchers used structural biology as a discovery tool and found that cGAS is present in the nucleus in an inactive state. They teamed up with the Ablasser lab at the EPFL to decipher the mechanism of cGAS inactivation by chromatin in cells.

Taking advantage of  cryo-electron microscopy (cryo-EM), the researchers derived the structure of cGAS bound to a nucleosome. They found that cGAS directly engages the histone proteins of nucleosomes. Once bound to the nucleosome, cGAS is "trapped" in a state in which it is unable to engage or sense naked DNA. It is then also unable to synthesize GMP-AMP and remains inactivated. cGAS, when present in the nucleus of healthy cells, is thus inactivated by chromatin, and does not participate in innate immune signaling in response to its own DNA.

 Ganesh R. Pathare et al. Structural mechanism of cGAS inhibition by the nucleosome, Nature (2020). DOI: 10.1038/s41586-020-2750-6

https://phys.org/news/2020-11-foreign-dna-innate-immune-sensor.html...

Comment by Dr. Krishna Kumari Challa on November 27, 2020 at 9:54am

Study is the first to link microbiota to dynamics of the human immune system

Researchers have uncovered an important finding about the relationship between the microbiota and the immune system, showing for the first time that the concentration of different types of immune cells in the blood changes in relation to the presence of different bacterial strains in the gut.

In recent years, the microbiota—the community of bacteria and other microorganisms that live on and in the human body—has captured the attention of scientists and the public, in part because it's become easier to study. It has been linked to many aspects of human health.

A multidisciplinary team from Memorial Sloan Kettering has shown for the first time that the gut microbiota directly shapes the makeup of the human immune system. Specifically, their research demonstrated that the concentration of different types of immune cells in the blood changed in relation to the presence of different bacterial strains in the gut. The results of their study, which used more than ten years of data collected from more than 2,000 patients, is being published November 25, 2020, in Nature.

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The data that were used in the study came from people receiving allogeneic stem cell and bone marrow transplants (BMTs). After strong chemotherapy or radiation therapy is used to destroy cancerous blood cells, the patient's blood-forming system is replaced with stem cells from a donor. For the first few weeks until the donor's blood cells—including the white blood cells that make up the immune system—have established themselves, the patients are extremely vulnerable to infections. To protect them during this time, patients are given antibiotics.

But many of these antibiotics have the unwanted side effect of destroying healthy microbiota that live in the gut, allowing dangerous strains to take over. When the patient's immune system has reconstituted, the antibiotics are discontinued, and the gut microbiota slowly starts to grow back.

The parallel recoveries of the immune system and the microbiota, both of which are damaged and then restored, gives us a unique opportunity to analyze the associations between these two systems.

Jonas Schluter et al. The gut microbiota is associated with immune cell dynamics in humans, Nature (2020). DOI: 10.1038/s41586-020-2971-8

https://medicalxpress.com/news/2020-11-link-microbiota-dynamics-hum...

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