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Comment by Dr. Krishna Kumari Challa on November 11, 2016 at 7:40am

Why Neanderthal DNA wasn't much successful...

Neanderthals and modern humans got separated  from a common ancestor about half a million years ago.

Living in colder climes in Eurasia, Neanderthals evolved barrel chests, large skulls and strong hands. In Africa, modern humans acquired shorter faces, a prominent chin and slender limbs. Then, roughly 50,000 years ago, the two species encountered one another and interbred, as modern humans spread out of Africa.

The legacy of this interbreeding has been the subject of much scientific inquiry in the past few years. Today, up to 4 percent of the genes of non-Africans are Neanderthal in origin.. These may have influenced a diverse range of traits, including keratin production, disease risk. Where did all the other Neanderthal DNA go? Why did a Neanderthal-human hybrid not prevail?

Two recent studies converge on an explanation. They suggest the answer comes down to different population sizes between Neanderthals and modern humans, and this principle of population genetics: In small populations, natural selection is less effective.

Neanderthals have this small population over hundreds of thousands of years, presumably because they’re living in very rough conditions. As a result, Neanderthals were more inbred than modern humans and accumulated more mutations that have a slightly adverse effect, such as increasing one’s risk of disease, but do not prevent one from reproducing .

After Neanderthals started mating with humans, natural selection in the larger human population started excluding.

http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pg...

Comment by Dr. Krishna Kumari Challa on November 10, 2016 at 6:22am

New type of atomic bond

Scientists have for the first time observed a weak atomic bond – in which an electron can grab and trap an atom – that was theorised 14 years ago. Researchers at Purdue University in the US observed a butterfly Rydberg molecule, a weak pairing of two highly excitable atoms that they predicted would exist more than a decade ago.

Rydberg molecules are formed when an electron is kicked far from an atom’s nucleus. Chris Greene, Professor of Physics and Astronomy at Purdue, and colleagues theorised in 2002 that such a molecule could attract and bind to another atom.

For all normal atoms, the electrons are always just one or two angstroms away from the nucleus, but in these Rydberg atoms you can get them 100 or 1,000 times farther away. Following preliminary work in the late 1980s and early 1990s, we saw in 2002 the possibility that this distant
Rydberg electron could bind the atom to another atom at a very large distance.

This electron is like a sheepdog. Every time it whizzes past another atom, this Rydberg atom adds a little attraction and nudges it towards one spot until it captures and binds the two atoms together.

A collaboration involving Greene and his postdoctoral associate Jesus Perez-Rios at Purdue and researchers at the University of Kaiserslautern in Germany has now proven the existence of the butterfly Rydberg molecule, so named for the shape of its electron cloud.  This new binding mechanism, in which an electron can grab and trap an atom, is really new from the point of view of chemistry. It’s a whole new way an atom can be bound by another atom.

The researchers cooled Rubidium gas to a temperature of 100 nano-Kelvin, about one ten-millionth of a degree above absolute zero. Using a laser, they were able to push an electron from its nucleus, creating a Rydberg atom, and then watch it.

Whenever another atom happens to be at about the right distance, you can adjust the laser frequency to capture that group of atoms that are at a very clear internuclear separation that is predicted by our theoretical treatment.

They were able to detect the energy of binding between the two atoms based on changes in the frequency of light that the Rydberg molecule absorbed.

The findings were published in the journal Nature Communications.

http://www.nature.com/articles/ncomms12820

Comment by Dr. Krishna Kumari Challa on November 9, 2016 at 7:28am

Supersolids: strange state of matter

Two teams of scientists report the creation of supersolids, which are both liquid and solid at the same time. Supersolids have a crystalline structure like a solid, but can simultaneously flow like a superfluid, a liquid that flows without friction.

Research teams from MIT and ETH Zurich both produced supersolids in an exotic form of matter known as a Bose-Einstein condensate. Reports of the work were published online at arXiv.org on October 26 (by the MIT group) and September 28 (by the Zurich group).

Bose-Einstein condensates are created when a group of atoms, chilled to near absolute zero, huddle up into the same quantum state and begin behaving like a single entity. The scientists’ trick for creating a supersolid was to nudge the condensate, which is already a superfluid, into simultaneously behaving like a solid. To do so, the MIT and Zurich teams created regular density variations in the atoms — like the repeating crystal structure of a more typical solid — in the system. That density variation stays put, even though the fluid can still flow.

The two groups of scientists formed their supersolids in different ways. By zapping their condensate with lasers, the MIT group induced an interaction that gave some of the atoms a shove. This motion caused an interference between the pushed and the motionless atoms that’s similar to the complex patterns of ripples that can occur when waves of water meet. As a result, zebralike stripes — alternating high- and low-density regions — formed in the material,  indicating that it was a solid.

Applying a different method, the ETH Zurich team used two optical cavities — sets of mirrors between which light bounces back and forth repeatedly. The light waves inside the cavities caused atoms to interact and thereby arrange themselves into a crystalline pattern, with atoms separated by an integer number of wavelengths of light.

J. Li et al. Observation of the supersolid stripe phase in spin-orbit coupled Bo.... arXiv:1610.08194. Posted October 26, 2016.

J. Léonard et al. Supersolid formation in a quantum gas breaking continuous translati.... arXiv:1609.09053. Posted September 28, 2016.

Comment by Dr. Krishna Kumari Challa on November 5, 2016 at 7:09am

Transient Weakening of Earth’s Magnetic Shield Probed by a Cosmic Ray Burst

The GRAPES-3 muon telescope located at TIFR's Cosmic Ray Laboratory in Ooty recorded a burst of galactic cosmic rays of about 20 GeV, on 22 June 2015 lasting for two hours.

The burst occurred when a giant cloud of plasma ejected from the solar corona, and moving with a speed of about 2.5 million kilometers per hour struck our planet, causing a severe compression of Earth's magnetosphere from 11 to 4 times the radius of Earth. It triggered a severe geomagnetic storm that generated aurora borealis, and radio signal blackouts in many high latitude countries.

Earth's magnetosphere extends over a radius of a million kilometers, which acts as the first line of defence, shielding us from the continuous flow of solar and galactic cosmic rays, thus protecting life on our planet from these high intensity energetic radiations. Numerical simulations performed by the GRAPES-3 collaboration on this event indicate that the Earth's magnetic shield temporarily cracked due to the occurrence of magnetic reconnection, allowing the lower energy galactic cosmic ray particles to enter our atmosphere. Earth's magnetic field bent these particles about 180 degree, from the day-side to the night-side of the Earth where it was detected as a burst by the GRAPES-3 muon telescope around mid-night on 22 June 2015. The data was analyzed and interpreted through extensive simulation over several weeks by using the 1280-core computing farm that was built in-house by the GRAPES-3 team of physicists and engineers at the Cosmic Ray Laboratory in Ooty.

Solar storms can cause major disruption to human civilization by crippling large electrical power grids, global positioning systems (GPS), satellite operations and communications.

The GRAPES-3 muon telescope, the largest and most sensitive cosmic ray monitor operating on Earth is playing a very significant role in the study of such events. 

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.171101

Comment by Dr. Krishna Kumari Challa on November 5, 2016 at 6:26am

An interesting  similarity between human cells and neutron stars

According to new research, we share at least one similarity with the neutron stars: the geometry of the matter that makes us. 

Researchers have found that the 'crust' (or outer layers) of a neutron star has the same shape as our cellular membranes. This could mean that, despite being fundamentally different, both humans and neutron stars are constrained by the same geometry.

To understand this finding, we need to quickly dive into the weird world of nuclear matter, which researchers call 'nuclear pasta' because it looks a lot like spaghetti and lasagne. 

This nuclear pasta forms in the dense crust of a neutron star thanks to long-range repulsive forces competing with something called the strong force, which is the force that binds quarks together.

In other words, two powerful forces are working against one another, forcing the matter – which consists of various particles – to structure itself in a scaffold-like (pasta) way.

"When you have a dense collection of protons and neutrons like you do on the surface of a neutron star, the strong nuclear force and the electromagnetic forces conspire to give you phases of matter you wouldn't be able to predict if you had just looked at those forces operating on small collections of neutrons and protons."

Now, it turns out that these pasta-like structures look a lot like the structures inside biological cells, even though they are vastly different.

This odd similarity was first discovered in 2014, when Huber was studying the unique shapes on our endoplasmic reticulum (ER) – the little organelle in our cells that makes proteins and lipids.

You can see the ER structures (left) compared to the neutron stars (right) below: 

University of California, Santa Barbara

The discovery brought both of the scientists together to compare and contrast the differences between the structures, such as the conditions required for them to form

Normally, matter is characterised by a phase – sometimes called its state – such as gas, solid, liquid Different phases are usually influenced by a plethora of various conditions, like how hot the matter is, how much pressure it’s under, and how dense it is.

These factors change wildly between soft matter (the stuff inside cells) and neutron stars (nuclear matter). After all, neutron stars form after supernovae explosions, and cells form within living things. With that in mind, it’s quite easy to see that the two things are very different.

For neutron stars, the strong nuclear force and the electromagnetic force create what is fundamentally a quantum mechanical problem.

"In the interior of cells, the forces that hold together membranes are fundamentally entropic and have to do with the minimisation of the overall free energy of the system. At first glance, these couldn't be more different."

The team’s work was published in Physical Review C.

Comment by Dr. Krishna Kumari Challa on October 29, 2016 at 6:29am

The continuing promotion of cranberry use to prevent recurrent UTI in the popular press or online advice seems inconsistent with the reality of repeated negative studies or positive studies compromised by methodological shortcomings.

Cranberries Don’t Prevent Urinary Tract Infections

Many think the fruit raises urine acidity and has a bacteria-battling compound 

Over the course of a year, taking cranberry capsules did nothing to stave off urinary tract infections (UTIs) among older women living in nursing homes, a U.S. study finds. There was no significant difference in the presence of bacteriuria plus pyuria in those who took cranberry capsules and those who took placebo capsules, the researchers found.

Originally, it was thought that eating or drinking cranberry products increased the acidity of urine and prevented UTIs. There was also speculation that proanthocyanidin in cranberries prevented bacteria from adhering to the bladder wall.

The results were published online October 27th in JAMA to coincide with presentation at Infectious Disease Week.

Comment by Dr. Krishna Kumari Challa on October 26, 2016 at 8:35am

A titanic volcano stopped a mega-sized earthquake in its tracks.

In April, pent-up stress along the Futagawa-Hinagu Fault Zone in Japan began to unleash a magnitude 7.1 earthquake. The rupture traveled about 30 kilometers along the fault until it reached Mount Aso, one of Earth’s largest active volcanoes. That’s where the quake met its demise, geophysicist Aiming Lin of Kyoto University in Japan and colleagues report online October 20 in Science. The quake moved across the volcano’s caldronlike crater and abruptly stopped, the researchers found.

Geophysical evidence suggests that a region of rising magma lurks beneath the volcano. This magma chamber created upward pressure plus horizontal stresses that acted as an impassable roadblock for the seismic slip powering the quake, the researchers propose. This rare meetup, the researchers warn, may have undermined the structural integrity surrounding the magma chamber, increasing the likelihood of an eruption at Aso.

http://science.sciencemag.org/content/early/2016/10/19/science.aah4629

Comment by Dr. Krishna Kumari Challa on October 26, 2016 at 8:30am

Scientists have found the first experimental evidence that an atomic nucleus can harbor bubbles. The unstable isotope silicon-34 has a bubblelike center with a paucity of protons. This unusual “bubble nucleus” could help scientists understand how heavy elements are born in the universe, and help scientists find new, ultraheavy stable isotopes.

In their quirky quantum way, protons and neutrons in a nucleus refuse to exist in only one place at a time. Instead, they are spread out across the nucleus in nuclear orbitals, which describe the probability that each proton or neutron will be found in a particular spot. Normally, due to the strong nuclear force that holds the two types of particles together, nuclei have a fairly constant density in their centers, regardless of the number of protons and neutrons they contain. In silicon-34, however, some scientists predicted that one of the proton orbitals that fills the center of the nucleus would be almost empty, creating a bubble nucleus. But not all theories agreed. “This was the reason for doing the experiment” .

In pursuit of the bubble nucleus, the scientists smashed silicon-34 nuclei into a beryllium target, which knocked single protons out of the nuclei to create aluminum-33. The resulting aluminum-33 nuclei were in excited, or high-energy, states and quickly dropped down to a lower energy by emitting photons, or light particles. By observing the energy of those photons, Sorlin and colleagues could reconstruct the orbital of the proton that had been kicked out of the nucleus.

The scientists found that they ejected few protons from the central orbital that theorists had predicted would be empty. While the orbital can theoretically hold up to two protons, it held only 0.17 protons on average. In silicon-34, the central proton density is about half that of a comparable nucleus, the scientists calculated, after taking into account other central orbitals that contain normal numbers of protons. (The density of neutrons in silicon-34’s center, however, is normal.)

As protons are added to nuclei, they fill orbitals in a sequential manner, according to the energy levels of the orbitals. Silicon-34 is special — it has a certain “magic” number of protons and neutrons in its nucleus. There are a variety of such magic numbers, which enhance the stability of atomic nuclei. A magic number of protons means that the energy needed to boost a proton into the next orbital is particularly high. This explains the bubble’s origin. For a proton to jump into the unfilled central orbital, it needs significantly more energy. So silicon-34’s center remains sparsely populated.  

It’s an interesting paper and indeed provides evidence for a bubble nucleus.  The research could help scientists understand the spin-orbit interaction, the interplay between a proton’s angular momentum in its orbital and its intrinsic angular momentum, or spin. The effect is important for keeping heavy nuclei stable. Figuring out the impact of that interaction in this unusual nucleus could help scientists better predict the potential location of the “island of stability,” a theorized region of the periodic table with heavy elements that may be stable for long periods of time.

A better grasp of the spin-orbit interaction could also help scientists learn how elements are forged in rare cosmic cataclysms such as the merging of two neutron stars. There, nuclei undergo a complex chain of reactions, swallowing up neutrons and undergoing radioactive decay. Modeling this process requires a precise understanding of the stability of various nuclei — a property affected by the spin-orbit interaction.

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3916.html

Comment by Dr. Krishna Kumari Challa on October 22, 2016 at 1:30pm

Reading old books without opening them 

Scientists have devised a way to read without cracking a volume’s spine or risking paper cuts (and no, we’re not talking about e-books). The new method uses terahertz radiation — light with wavelengths that are between microwave and infrared waves — to view the text of a closed book. The technique is not meant for your average bookworm, but for reading rare books that are too fragile to open.

Barmak Heshmat of MIT and colleagues started small, with a nine-page book of thick paper that had one letter inked on each page. By hitting the book with terahertz radiation and looking at the reflected waves, the scientists could read the letters within.

Letters on pages 7 through 9 of a closed book are decoded using terahertz radiation. After isolating the reflected radiation from each page, the technique selects the frequency of radiation that provides the best contrast between ink and paper. An algorithm decodes the letters and then their locations inside the book. 

Differences in the way the radiation interacts with ink and paper allowed the researchers to pick out shadowy outlines of the letters, and a letter-recognition algorithm automatically decoded the characters. The scientists could tell one page from another by using precise timing information: On the later pages, the waves penetrated deeper before reflecting and, therefore, took longer to return.

Historians also may be able to use the technique to find an artist’s signature hidden beneath layers of a painting. 

http://www.nature.com/articles/ncomms12665

Comment by Dr. Krishna Kumari Challa on October 22, 2016 at 1:14pm

AT LEAST two trillion galaxies — 10 times more than scientists thought — exist within the observable universe. And we can’t even see most of them.

 

A group of international astronomers compiled 20 years of images from the Hubble Space Telescope and other international observatories to create a 3D model of the 200 billion galaxies already estimated to exist.

But the model instead revealed that there are at least one trillion eight hundred billion more out there. Only 10 per cent of these are visible to us even with our strongest telescopes.

“It boggles the mind that over 90 per cent of the galaxies in the universe have yet to be studied,” said Christopher Conselice, who led the study published Thursday in The Astrophysical Journal.

Since the scientists were observing deep space, they essentially gazed 13 billion light-years into the past and discovered that the early universe contained more galaxies than it does today. Many of those galaxies have since merged to form larger celestial objects.

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