Comment

Comment by Dr. Krishna Kumari Challa on March 25, 2021 at 11:20am

All meat that has been smoked, salted, cured, dried or canned is considered processed.

Comment by Dr. Krishna Kumari Challa on March 25, 2021 at 6:44am

Why you can't compare Covid-19 vaccines

--
Vaccine side effects are actually a good thing

Comment by Dr. Krishna Kumari Challa on March 24, 2021 at 10:39am

Ten years later, here’s what Fukushima’s damaged reactors look like today

Comment by Dr. Krishna Kumari Challa on March 24, 2021 at 10:30am

Researchers reveal how a cell mixes its mitochondria before it divides

In a landmark study, a team led by researchers at the Perelman School of Medicine at the University of Pennsylvania has discovered and filmed the molecular details of how a cell, just before it divides in two, shuffles important internal components called mitochondria to distribute them evenly to its two daughter cells. The finding, published in Nature, is principally a feat of basic cell biology, but this line of research may one day help scientists understand a host of mitochondrial and cell division-related diseases, from cancer to Alzheimers and Parkinsons.

Mitochondria are tiny oxygen reactors that are crucial for energy production in cells. It was found in the study that a protein called actin, which is known to assemble into filaments that play a variety of structural roles in cells, also has the important task of ensuring an even distribution of mitochondria prior to cell division. Thanks to this system, the two new cells formed by the division will end up with approximately the same mass and quality of these critical energy producers.

Mitochondria, which can number from a handful to tens of thousands per cell, depending on the cell type, are probably especially important to mix evenly. They are critical for the health of a cell, and contain their own small DNA genomes—new mitochondria can’t be produced in a cell except by the splitting of mitochondria inherited from the mother cell.

https://www.pennmedicine.org/news/news-releases/2021/march/penn-med...

https://researchnews.cc/news/5797/Penn-Medicine-researchers-reveal-...

Comment by Dr. Krishna Kumari Challa on March 24, 2021 at 10:19am

Evidence of new physics at CERN? Why we're cautiously optimistic ab...

When CERN's gargantuan accelerator, the Large Hadron Collider (LHC), fired up ten years ago, hopes abounded that new particles would soon be discovered that could help us unravel physics' deepest mysteries. Dark matter, microscopic black holes and hidden dimensions were just some of the possibilities. But aside from the spectacular discovery of the Higgs boson, the project has failed to yield any clues as to what might lie beyond the standard model of particle physics, our current best theory of the micro-cosmos.

Comment by Dr. Krishna Kumari Challa on March 24, 2021 at 8:50am

Big bang myths - part 2

The big band didn't have  a center.  

If we imagine the Big Bang as an explosion, it's easy to think that it exploded outwards, from a center. That's how explosions work.

But that wasn't the case with the Big Bang. Almost all galaxies are moving away from us, in all directions. It seems like the Earth was the center of the beginning of the universe. But it wasn't.

All other observers would see the same thing from their home galaxy.

The universe is expanding everywhere at the same time. The Big Bang didn't happen in any particular place.

It happened everywhere.

It's true that our entire observable universe was gathered incredibly tightly together in very little space at the beginning of the Big Bang.

But how can the universe be infinite, and at the same time have been so small?

You might read that the universe was smaller than an atom at first and then the size of a football. But that analogy insinuates that space had boundaries in the beginning, and an edge.

There's nothing that says that the universe wasn't already infinite at the Big Bang.

The whole observable universe comes from a tiny little area that you can call a point. But the point next to it has also expanded, and the next point as well. It's just that it's so far away from us that we can't observe it.

Maybe you've heard that the universe began as a singularity. Or that it was infinitely small, hot and so on. That might be true, but a lot of physicists don't think it's a correct understanding.

Singularities are an expression for mathematics that breaks down and can't be described with ordinary physics.

"The universe today is a little bigger than it was yesterday. And it's even a little bigger still than it was a million years ago. The Big Bang theory involves extrapolating this back in time. Then you need a theory for that: and that's the general theory of relativity."

"If I extrapolate all the way back, the universe gets smaller and smaller, it gets denser and denser, and warmer and warmer. Finally you get to a point where it's really small, really hot and dense. That's actually the Big Bang theory: that the universe started in such a condition. That's where you really have to stop.

If you run the general relativity theory all the way back you reach a point of infinitely high density and heat, where the size is zero.

"That's pure mathematical extrapolation beyond what the theory actually allows.

You then come to a point where the energy density and temperatures are so high that we no longer have physical theories to describe them.

https://phys.org/news/2021-03-myths-big.html?utm_source=nwletter&am...

Comment by Dr. Krishna Kumari Challa on March 24, 2021 at 8:42am

Five myths about the Big Bang

The whole universe was packed together in an infinitely small point, then it exploded, and the entire mass that made up the universe was sent out into space.

No, this is not how it happened.

The Big Bang theory is that about 14 billion years ago the universe was in a state that was much warmer and much denser, and that it expanded. That's it, it's not much more than that. 

Since then space has continued to expand and has become colder.

Based on the theory, scientists have gained a clearer overview of the history of the universe, such as when elementary particles were formed and when atoms, stars and galaxies formed.

If you take the entire observable universe and rewind all the way back, everything fit into a very, very small area. An explosion where the mass explodes in all directions is not an accurate picture of the Big Bang.

The universe itself expands, space itself expands.

So it isn't the galaxies that are moving apart, but space that's expanding.

We can think of it as a ball of dough with raisins. The dough represents space and the raisins are the galaxies. Set the dough to rise, and the raisins will end up further apart, without actually having moved. At the same time, it's true that galaxies also move due to mutual gravitational attraction—that's an additional effect.

A few galaxies are blue-shifting, meaning they're moving towards us. This applies to some nearby galaxies. But over large distances, this effect is eclipsed by Hubble-Lemaître's law, which states how fast galaxies are moving away in proportion to distance. In fact, the distance increases faster than light between points that are extremely far apart.

The universe doesn't expand into anything. Scientists don't believe that the universe has an edge.

That which we call the observable universe is a bubble surrounding us that is 93 billion light-years in diameter. The more distant something is that we look at, the farther back in time we're seeing. We can't observe or measure anything farther away than the distance light has managed to travel towards us since the Big Bang.

Since the universe has been expanding, the observable universe is counterintuitively larger than 14 billion light-years.

But scientists calculate that the universe outside our bubble is much, much larger than that, perhaps infinite.

The universe can be "flat," it appears. That would mean that two light rays would remain parallel and never meet. If you tried to travel to the end of the universe, you would never reach it. The universe goes on infinitely.

If the universe has positive curvature, it could in theory be finite. But then it would be like a kind of strange sphere. If you traveled to the "end" you would end up in the same place you started, no matter which direction you took. It's a bit like being able to travel around the world and ending up back where you started.

In either case, the universe can expand without having to expand into anything.

An infinite universe that's getting bigger is still infinite. A "spherical universe" has no edge.

Myths about big bang - part 1 

Comment by Dr. Krishna Kumari Challa on March 24, 2021 at 8:30am

To produce more food, scientists look to get more mileage out of plant enzymes

Enzymes play essential roles in the cells of every living thing, from bacteria, to plants to people. Some do their jobs a few times and fizzle out. Others can repeat a task hundreds of thousands of times before they quit.

Organisms put a lot of energy into replacing worn out enzymes, energy they could put into other processes. In plants grown for food, fuel, fiber or other purposes, longer lasting enzymes could translate into increased yields.

 Andrew D. Hanson el al., "The number of catalytic cycles in an enzyme's lifetime and why it matters to metabolic engineering," PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2023348118

https://phys.org/news/2021-03-food-scientists-mileage-enzymes.html?...

**

Comment by Dr. Krishna Kumari Challa on March 22, 2021 at 2:15pm

The Sensitivity of Human Fingertips Is Greater Than We Ever Imagined

Skin – the largest organ in the human body – envelops us from head to toe, letting us touch, feel, and interact with the outside world. But there's one part of that organ even more attuned to touch than any other.

A new study has revealed just how receptive the sensory neurons in our fingers are: As it turns out, we can detect touch on the minuscule scale of a single fingerprint ridge.

Sensory neurons attached to receptors are dotted just underneath the skin's surface, allowing us to detect touch, vibration, pressure, pain, and lots more. Our hands alone contain tens of thousands of these neurons, each one with receptors on a small surface area of the skin, called a receptive field.

To map these fields, the researchers strapped down the arms of 12 healthy people and glued their fingernails to plastic holders to really make sure they couldn't move. A machine then wheeled tiny, 0.4 millimeter-wide cones around 7 mm apart across their skin (you can see what that looks like below) and the team recorded each neuron's response using an electrode in the participants' arms.

Specifically, they were mapping the more sensitive zones – known as subfields – within these receptive fields.

By calculating the sensory neuron detection areas and mapping them onto the fingerprint, the team found that the detection area's width was equivalent to the width of one fingerprint ridge.

These subfields also didn't move when the machine wheeled the dots faster or slower, or changed directions, suggesting that these sensitive areas are anchored to the fingerprint ridges themselves.

"We report that the sensitivity of the subfield arrangement for both neuron types on average corresponds to a spatial period of ~0.4 mm and provide evidence that a subfield's spatial selectivity arises because its associated receptor organ measures mechanical events limited to a single papillary ridge," the researchers write in their new paper.

https://www.jneurosci.org/content/early/2021/03/08/JNEUROSCI.1716-2...

https://www.sciencealert.com/our-fingertips-have-a-secret-weapon-th...

Comment by Dr. Krishna Kumari Challa on March 22, 2021 at 2:09pm

Scientists Just Demonstrated How These 'Spiders' Might Form on Mars

We may not have detected life on Mars, but we have found 'spiders'... of a sort.

They're called araneiforms: dark, spider-like systems of branching, fractal troughs found only in the southern polar regions of the red planet. There's nothing like them on Earth, or any other planet in the Solar System.

That makes it tricky to understand what creates them, but scientists have just obtained the first physical evidence that supports the most popular model, known as Kieffer's hypothesis. According to this idea, the spider-like forms are shaped by the direct sublimation of frozen carbon dioxide (CO₂).

"This research presents the first set of empirical evidence for a surface process that is thought to modify the polar landscape on Mars

https://www.nature.com/articles/s41598-021-82763-7

https://www.sciencealert.com/there-are-spiders-on-mars-like-nothing...

• ‹ Previous
• 1
• …
• 410
• 411
• 412
• 413
• 414
• …
• 839
• Next ›
• Page