A lonely spacecraft is nearing Pluto after a three billion-mile journey lasting almost nine years. Nasa’s New Horizons probe awoke from hibernation on December 6 and is preparing to explore the Solar System’s mysterious ‘ninth planet’.
(Phys.org)—Light behaves both as a particle and as a wave. Since the days of Einstein, scientists have been trying to directly observe both of these aspects of light at the same time.
Quantum mechanics tells us that light can behave simultaneously as a particle or a wave. However, there has never been an experiment able to capture both natures of light at the same time; the closest we have come is seeing either wave or particle, but always at different times. Taking a radically different experimental approach, EPFL scientists have now been able to take the first ever snapshot of light behaving both as a wave and as a particle. The breakthrough work is published in Nature Communications.
When UV light hits a metal surface, it causes an emission of electrons. Albert Einstein explained this "photoelectric" effect by proposing that light – thought to only be a wave – is also a stream of particles. Even though a variety of experiments have successfully observed both the particle- and wave-like behaviors of light, they have never been able to observe both at the same time.
A research team led by Fabrizio Carbone at EPFL has now carried out an experiment with a clever twist: using electrons to image light. The researchers have captured, for the first time ever, a single snapshot of light behaving simultaneously as both a wave and a stream of particles.
The experiment is set up like this: A pulse of laser light is fired at a tiny metallic nanowire. The laser adds energy to the charged particles in the nanowire, causing them to vibrate. Light travels along this tiny wire in two possible directions, like cars on a highway. When waves traveling in opposite directions meet each other they form a new wave that looks like it is standing in place. Here, this standing wave becomes the source of light for the experiment, radiating around the nanowire.
University of Virginia School of Medicine have discovered that a gene called Oct4 — which scientific dogma insists is inactive in adults — actually plays a vital role in preventing ruptured atherosclerotic plaques inside blood vessels, the underlying cause of most heart attacks and strokes.
The researchers found that Oct4 controls the conversion of smooth muscle cells into protective fibrous “caps” inside plaques, making the plaques less likely to rupture. They also discovered that the gene promotes many changes in gene expression that are beneficial in stabilizing the plaques. In addition, the researchers believe it may be possible to develop drugs or other therapeutic agents that target the Oct4 pathway as a way to reduce the incidence of heart attacks or stroke.
The researchers are also currently testing Oct4′s possible role in repairing cellular damage and healing wounds, which would make it useful for regenerative medicine.
Oct4 is one of the “stem cell pluripotency factors” described by Shinya Yamanaka, PhD, of Kyoto University, for which he received the 2012 Nobel Prize. His lab and many others have shown that artificial over-expression of Oct4 within somatic cells grown in a lab dish is essential for reprogramming these cells into induced pluripotential stem cells, which can then develop into any cell type in the body or even an entire organism.
“Finding a way to reactivate this pathway may have profound implications for health and aging,” said researcher Gary K. Owens, director of UVA’s Robert M. Berne Cardiovascular Research Center. “This could impact many human diseases and the field of regenerative medicine. [It may also] end up being the ‘fountain-of-youth gene,’ a way to revitalize old and worn-out cells.”
They worked by torchlight, following the same procedure hour after hour: wrench a stalagmite off the cave floor, remove the tip and base, and carefully lay it with the others.
Today we can only guess as to why a group of Neanderthals built a series of large stalagmite structures in a French cave – but the fact they did provides a rare glimpse into our extinct cousin’s potential for social organisation in a challenging environment.
Gone are the days when we thought of Neanderthals as crude and unintelligent.
So will we ever be able to model something as complex as the human brain using computers? After all, biological systems use symmetry and interaction to do things that even the most powerful computers cannot do – like surviving, adapting and reproducing. This is one reason why binary logic often falls short of describing how living things or human intelligence work. But our new research suggests there are alternatives: by using the mathematics that describe biological networks in the computers of the future, we may be able to make them more complex and similar to living systems like the brain.
How the hidden mathematics of living cells could help us decipher the brain
MIT scientists use new super-resolution imaging technique to illuminate a new trigger for gene transcription: tiny, short-lived clusters of enzymes that may jump-start the production of mRNA, and the synthesis of proteins, vital for life.
Researchers at Tsinghua University in Beijing have created a mirror-image version of a protein that performs two of the most fundamental processes of life: copying DNA and transcribing it into RNA.
The work is a “small step” along the way to making mirror-image life forms, says molecular biologist Jack Szostak of Harvard Medical School in Boston, Massachusetts. “It’s a terrific milestone,” adds his Harvard colleague George Church, who hopes one day to create an entire mirror-image cell.
Many organic molecules are ‘chiral’: that is, they can exist in mirror-image forms that cannot be superimposed, like a right-handed and left-handed glove. But life almost always employs one version: cells use left-handed amino acids, and have DNA that twists like a right-handed screw, for instance.
Life forms created in this mirrored way would not be able to use any of the biological material of our normal world.
In their research paper, the Tsinghua researchers also present their work as an effort to investigate why life’s chirality is the way it is. This remains mysterious: it may simply be down to chance, or it could have been triggered by a fundamental asymmetry in nature.
But Steven Benner, at the Foundation for Applied Molecular Evolution in Alachua, Florida, says it’s unlikely that creating a mirror form of biochemical life could shed any light on this question. Almost every physical process behaves identically when viewed in a mirror. The only known exceptions — called ‘parity violations’ — lie in the realm of subatomic physics. Such tiny differences would never show up in these biochemical experiments, says Benner. (He is also interested in making DNA that can avoid unwanted degradation by natural enzymes or viruses, but rather than using mirror-DNA, he has created artificial DNA with non-natural building blocks.)
Church’s ultimate goal, to make a mirror-image cell, faces enormous challenges. In nature, RNA is translated into proteins by the ribosome, a complex molecular machine. “Reconstructing a mirror-image of the ribosome would be a daunting task,” says Zhu. Instead, Church is trying to mutate a normal ribosome so that it can handle mirror-RNA.
Church says that it is anyone’s guess as to which approach might pay off. But he notes that a growing number of researchers are working on looking-glass versions of biochemical processes. “For a while it was a non-field,” says Church. “But now it seems very vibrant.”
Australian researchers have created a “bionic spinal cord.” They claim that this device could give paralyzed people significant hope of walking again. And if that’s not enough, it could do it utilizing the power of thought and without the necessity of open brain surgery.
A research team from the Vascular Bionics Laboratory at the University of Melbourne developed the novel neural-recording device, which both eschews invasive surgery and decreases the risks of a blood-brain barrier breach by being implanted into the brain’s blood vessels.
Developed under DARPA’s Reliable Neural-Interface Technology (RE-NET) program, the Stentrode can potentially safely expand the use of brain-machine interfaces (BMIs) in the treatment of physical disabilities and neurological disorders.
The researchers describe their “proof-of-concept results” which come from a study conducted on sheep, demonstrating high-fidelity measurements taken from the region of the brain responsible for controlling voluntary movement (called the motor cortex) with the use of the novel device which, as it happens, is just about the size of a paperclip.
Notably, the device records neural activity that has been shown in pre-clinical trials to move limbs through an exoskeleton.
The team, led by neurologist Thomas Oxley, M.D., published their study in an article in the journal Nature Biotechnology.
Is dark energy the reason time moves forward? BRENDAN COLE 20 MAY 2016
For years, physicists have attempted to explain dark energy - a mysterious influence that pushes space apart faster than gravity can pull the things in it together. But physics isn’t always about figuring out what things are. A lot of it is figuring out what things cause.
And in a recent paper, a group of physicists asked this very question about dark energy, and found that in some cases, it might cause time to go forward.
When you throw a ball into the air, it starts with some initial speed-up, but then it slows as Earth’s gravity pulls it down. If you throw it fast enough (about 11 km per second, for those who want to try), it’ll never slow down enough to turn around and start falling back towards you, but it’ll still move more slowly as it moves away from you, because of Earth’s gravity.
Physicists and astronomers in the 1990s expected something similar to have occured after the big bang - an event that threw matter out in all directions. The collective gravity from all that matter should have slowed it all down, just like the Earth slows down the ball. But that’s not what they found.
Instead, everything seems to have sped up. There’s something pervading the Universe that physically spreads space apart faster than gravity can pull things together. The effect is small - it’s only noticeable when you look at far-away galaxies - but it’s there. It’s become known as dark energy - "dark", because no one knows what it is.
Science is nothing if not the process of humans looking for things they can’t explain, so this isn’t the first time the Universe has stumped us. For centuries, one of those stumpers has been time itself: Why does time have an arrow pointing from the past to the present to the future?
It might seem like a silly question - I mean, if time didn’t go forward, then effects would precede causes, and that seems like it should be impossible - but it’s less of one than you might think.
The Universe, as far as we can tell, only operates according to laws of physics. And just about all of the laws of physics that we know are completely time-reversible, meaning that the things they cause look exactly the same whether time runs forward or backward.
One example is the path of a planet going around a star, which is governed by gravity. Whether time runs forward or backward, planetary orbits follow the exact same paths. The only difference is the direction of the orbit.
But one important piece of physics isn’t time-reversible, and that’s the second law of thermodynamics. It states that as time moves forward, the amount of disorder in the Universe will always increase. Just like dark energy, it’s something we’ve noticed about the Universe, and it’s something that we still don’t totally understand - though admittedly we have a better idea of it than we do of dark energy.
Physicists have, for this reason, reluctantly settled on the second law as the source of time’s arrow: disorder always has to increase after something happens, which requires that time can only move in one direction.
So physicists A. E. Allahverdyan from the Yerevan Physics Institute and V. G. Gurzadyan from Yerevan State University, both in Armenia, decided to see if - at least in a limited situation - dark energy and the second law might be related. To test it, they looked at the simple case of something like a planet orbiting a star with a changing mass.
They found that if dark energy either doesn’t exist or if it pulls space together, the planet just dully orbits the star without anything interesting happening. There’s no way to tell an orbit going forward in time from one going backward in time.
But if dark energy pushes space apart, like it does in our Universe, the planet eventually gets thrown away from the star on a path of no return. This gives us a distinction between the past and the future: run time one way, and the planet is flung off, run it the other way, and the planet comes in and gets captured by the star.
Dark energy naturally leads to an arrow of time.
The authors stress that this is a really limited situation, and they’re certainly not claiming dark energy is the reason time only ever moves forward. But they’ve shown a possible link between thermodynamics and dark energy that could help us to understand either - or maybe both - better than we ever have.
The research has been published in Physical Review E.
These beautiful photographic patterns are constructed from daily snapshots that Lisa A Frank takes while walking in the woods, then the images are “sewn” together through extreme image layering and masking.
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