Sabtu, 30 November 2013

Comet ISON was passed away from Sun, Did It Survive?

A smaller, paler version of Comet ISON may have survived incineration in the sun's corona and may be brightening, scientists said on Friday.
Since its discovery in September 2012, Comet ISON has been full of surprises. It started off extremely bright, considering its great distance from the sun at the time, beyond Jupiter's orbit.
As it drew closer, it did not brighten as much as expected, raising doubts about its size and the amount of water it contained. Ice in a comet's body vaporizes from solar heating, causing a bright stream of particles to trail the body in a distinctive tail.
Conflicting pictures of the comet's future continued until Thursday when ISON apparently flew too close to the sun. Its long tail and nucleus seemingly vaporized in the solar furnace, dashing hopes of a naked-eye comet visible in Earth's skies in December.
But late on Thursday, ISON surprised again.
"A bright streak of material streaming away from the sun appeared in the European Space Agency and NASA's Solar and Heliospheric Observatory later in the evening," NASA wrote on its website on Friday.

"The question remains whether it is merely debris from the comet, or if some portion of the comet's nucleus survived," the U.S. space agency said.
Preliminary analysis suggests that at least a small nucleus is intact.
"One could almost be forgiven for thinking that there's a comet in the images," astrophysicist Karl Battams, with the Naval Research Laboratory in Washington, wrote in a blog posted Thursday night.

This time-lapse image shows Comet ISON approaching and leaving during its slingshot around the sun – represented by the white circle -- on Nov. 28, 2013. The ISON images clearly outline the curve of the comet's orbit path. The images were captured by ESA/
This time-lapse image shows Comet ISON approaching and leaving during its slingshot around the sun – represented by the white circle -- on Nov. 28, 2013. The ISON images clearly outline the curve of the comet's orbit path. The images were captured by ESA/NASA's SOHO mission.
View full size image"Right now it does appear that a least some small fraction of ISON has remained in one piece and is actively releasing material," Battams wrote.
The comet was discovered last year by two amateur astronomers using Russia's International Scientific Optical Network, or ISON.
Comets are believed to be frozen remains left over from the formation of the solar system some 4.5 billion years ago.
The family of comets that ISON is from resides in the Oort Cloud, which is about 10,000 times farther away from the sun than Earth, halfway to the next star.
Computer models show it left the outer edge of the solar system about 5.5 million years ago and began journeying toward the sun.
At its closest approach on Thursday, it passed just 730,000 miles (1.2 million km) from the sun's surface and experienced temperatures reaching 5,000 degrees Fahrenheit (2,760 degrees Celsius.)

"This has unquestionably been the most extraordinary comet that ... I, and many other astronomers, have ever witnessed," Battams wrote. "This story isn't over yet."


Senin, 18 November 2013

Immune memory explained

While the principle of immune memory has been known for decades, the exact molecular mechanisms underpinning it have remained a mystery. Australian scientists have now unraveled part of that mystery, identifying the role of a gene called STAT3, which acts as a kind of roundabout, directing chemical messenger molecules to various destinations.
An infection, or a vaccination, ‘primes’ the immune system, so that when you next encounter the same invader, your body ‘remembers’ it and quickly makes large amounts of exactly the right antibodies to quash the infection.
Once a cell is primed, traffic on the STAT3 roundabout speeds up enormously, as if the road has been upgraded and the signage much improved.
Primed immune cells, known as ‘memory B cells’, behave very differently from ‘naïve B cells’, which have never seen infection. Memory B cells act with great speed and efficiency, removing a pathogen so quickly that people frequently remain unaware they have been infected.
Patients with the rare immunodeficiency disorder, Hyper IgE Syndrome, caused by mutations in the STAT3 gene, have a ‘functional antibody deficiency’. While you can detect antibodies in their blood, those antibodies are not very good at fighting specific diseases or infections.
Through studying the blood cells of Hyper IgE patients over time, Associate Professor Stuart Tangye, Dr Elissa Deenick and Danielle Avery, from Sydney’s Garvan Institute of Medical Research, have gained considerable insight into the STAT3 gene. They recently observed that naïve B cells in Hyper IgE patients barely respond to important signaling molecules, whereas their memory B cells behave in the same way as those of healthy people.
The lab members realised that naïve B cells need a very strong chemical signal indeed – targeting STAT3 – to kick-start antibody production. Conversely, memory B cells only need faint signals to generate a huge antibody response. Even STAT3-compromised memory cells from Hyper IgE patients are functional. This breakthrough finding is published in the Journal of Experimental Medicine, now online.

Sabtu, 16 November 2013

39 Minutes: Quantum Bits Store Data for Record Time

The pipe dream of speedy quantum computers may be a bit closer to reality.
For the first time, physicists have coaxed a quantum bit of information to maintain its superposed state, in which quantum bits stay as both a 1 and a 0 at the same time, for 39 minutes at room temperature, at least 10 times longer than previously reported.
The new achievement, described today (Nov. 14) in the journal Science, removes a major obstacle to making a viable quantum computer that can recover from noise and other potential errors.

Quantum computers

In a traditional computer, information is stored as bits of information that are 1s or 0s. But by taking advantage of quantum mechanics, the strange laws that govern the very small, scientists can create a bit of information in multiple states at once — essentially a bit that is both a 1 and a 0, or even many 1s and 0s at once. That could then be used to perform many calculations at once, enabling computers to solve big data problems that previously seemed hopelessly intractable, said study co-author Stephanie Simmons, a quantum physicist at the University of Oxford. [Twisted Physics: 7 Mind-Blowing Findings]

"Quantum bits support an exponential amount of information, so this can give rise to an exponential speed-up in computation time," Simmons told LiveScience.
But quantum computers also make error correction trickier. Normally, computers compensate for the occasional wrong bit of information by creating redundancy. If three or five or seven bits are storing the same data, then it's easy to take a majority vote to get the right answer most of the time.

But it's impossible to copy the states of quantum bits, so once a bit decays, that information is lost. One solution is to create bits that last a longer amount of time and can do more calculations before decaying.

Long-lived bits

Toward that end, Simmons, along with colleagues at Simon Fraser University in Canada, took a tiny slice of silicon that contained small amounts of elements such as phosphorus. They encoded information in the spin — essentially the magnetic orientation — of the phosphorus nuclei, which can be in an up, down or in-between orientation.

The team then cooled the system to just 4 degrees Celsius above absolute zero, or minus 269 C (minus 452 degrees Fahrenheit). They then used magnetic pulses to create the superposition of magnetic spins in the phosphorus nuclei, meaning the nuclei are in multiple states at once. [Wacky Physics: The Coolest Quantum Particles Explained]

At the coolest temperatures, about 37 percent of the phosphorus ions maintained their spin state for more than three hours. When the team ramped up to room temperature, the quantum states were conserved for 39 minutes.

It takes only one hundred-thousandth of a second to do a calculation by flipping the spin of a phosphorus nucleus. So a quantum bit could perform 2 million operations before the system decays by 1 percent, Simmons said. (Physicists reporting this week in the journal Nature found a way to get qubits to remain in their superposed state for 10 minutes at extremely cold temperatures, using the magnetic properties of a rare earth element called holmium and the symmetry of platinum.)

In theory, the new advance means quantum computing could be used not just for doing calculations like a processor, but also for storing data. And unlike other systems, the materials the team used are already broadly used in traditional computers.

"The nice thing about silicon is that there's a huge industry that's been put together to bring silicon systems up to high quality," Simmons said.

Long road to go

The findings are genuinely exciting, Scott Aaronson, a computer scientist at the Massachusetts Institute of Technology, who was not involved in the research, said in an email.

"The best room-temperature coherence times I had seen cited before were less than a minute," Aaronson said. (Coherence time refers to the amount of time the nuclei remain superposed.)
Still, there are several obstacles to be overcome before laptops are replaced by quantum computers — namely, figuring out how to address individually each quantum bit, and getting them to communicate with each other for calculations, without spoiling the long lifetimes, said Aram Harrow, a computer scientist also at MIT, who was also not involved in the study.


'Rare' Atom Finding May Advance Quantum Computers

Quantum computers could crack codes and run more complex simulations than current machines, but actually building one is hard to do. The bits that store this complex data don't last long, because they are made of single atoms that get knocked around by stray electrons and photons in the environment.

Enter a team of physicists at Germany's Karlsruhe Institute of Technology. They found a way to get the bits to last long enough to do computations with, using the magnetic properties of a rare earth element called holmium and the symmetry of platinum. The experiment, detailed in tomorrow's (Nov. 14) issue of the journal Nature, is an important step in creating quantum computers and making quantum memory useful.

What makes quantum computers powerful is the nature of the bit. Ordinary computers have bits that are 1 or 0, stored in the current in a circuit or the alignment of magnetic fields on a disk. Due to theweirdness of quantum physics, quantum bits, called qubits, can be both 0 and 1 at the same time. That means a quantum computer can do certain kinds of calculations much, much faster. [Wacky Physics: The Coolest Quantum Particles Explained]

One way for qubits to store information in the so-called spin magnetic moments of atoms. Elementary particles such as electrons can have spins that are either up or down. The total spins of the electrons — each has a spin of one-half — will induce the magnetic moment, which is a way of measuring how much torque a magnetic field might exert on a loop of wire. In atoms, the moment has a direction, just like the spins, and it is either up or down.

Magnetic moments

In the study, led by Toshio Miyamachi, the researchers placed a single atom of holmium on a sheet of platinum with a scanning tunneling microscope. The holmium atom's moments were in a certain state, either up or down. That up or down state represented a bit of information, a 1 or 0 that makes up the language of computers. [Facts About Rare Earth Elements (Infographic)]
To cut down on the chances that a stray photon or electron would interact with the holmium atom, the whole apparatus operates at near absolute zero temperatures.

Ordinarily they would have expected the holmium's magnetic moment state to last a few milliseconds at most. Physicist Wulf Wulfhekel, whose lab did the work, told LiveScience that other research groups have managed that. But his lab group managed to keep the holmium in a given state for about 10 minutes. To a computer, that's a long time.

"One of the main problems with quantum computers is that the quantum bit loses its information rather quickly… In our case, you would have 10 minutes time to perform the calculation," Wulfhekel wrote in an email. 

The key to the long-lasting spin magnetic moment state was the arrangement of atoms in the platinum. Atoms' spin states get upset because in any metal, a few electrons are always on the move. So when a holmium (or any other) atom is on top of the platinum layer, the spin state of a passing electron will link to that of the holmium atom storing the bit and flip the magnetic moment, ruining the quantum state.

The platinum atoms, though, were in a pattern that had three-fold symmetry, which means that an object rotated one-third of the way around looks the same as when you start. If you were the size of a holmium atom and standing on the platinum, you'd see the same pattern turning 120 degrees, like a set of hexagonal or triangular tiles on a floor, Wulfhekel said.
The total spin of the holmium's inner electrons adds up to 8 — and that number isn't evenly divisible by three, which is the symmetry of the platinum. That means the holmium atoms are "invisible" to the electrons moving through the platinum.

"This is really a beautiful result," said Michael Flatté, a professor of physics at the University of Iowa and an expert on spintronics. Flatté, who was not involved in the research, said the paper is likely to be influential because it shows another approach to stabilizing spin states using the structure of the material itself.

Better than diamond?

Even so, there's still some way to go. Flatté noted that there are other materials that show this phenomenon — one of them is diamond, and it doesn't need to be kept at cryogenic temperatures. But the problem is that for a computer to be useful one has to be able to manipulate the bits. Bigger atoms, like heavy metals, are easier to work with because it's possible to move them around with electric or magnetic fields.
That's one reason this work is important, Flatté said. Miyamachi and Wulfhekel found a way around the trade-off between atoms that are easy to interact with, but at the same time can hang on to their quantum states.

"This is an appealing system," he said. "They still have a ways to go to challenge diamond."
Wulfhekel said his experiment only involved a single atom, and to be useful as a real computer it would require more, something that will be the focus of future work.

The team will also look at other elements. Praseodymium is a possibility, though Wulfhekel said he hasn't tried it yet. The bit-storing atoms have to have spins that have a non-integral relationship to the symmetry of the atoms around them, so that limits the number of elements available.

"One could be promethium, but that's radioactive," he said.

Samsung Galaxy S5 concept packs flexible screen and aluminium unibody

samsung galaxy s5 concept 1
The next flagship Galaxy S smartphone will be a radical break with form. Or at least it will be if the Samsung-fixated sorts at have anything to do with it.
A designer at the site has worked up a concept phone packing the flexible screen technology that’s been earmarked for Samsung phones for what feels like ages. But which has been omitted so far, presumably because it’s not market-ready yet.
The 5.3-inch flexible OLED YOUM screen wraps around the edges of the phone, with touch-sensitive controls where you’d normally expect to find a physical volume rocker. The standard physical home button has gone the way of all flesh too and is replaced by a touch sensor.
samsung galaxy s5 concept 2
Interestingly given the rash of criticism Samsung copped for the Galaxy S3 and S4's 'cheap-feeling' plastic construction, the creator of the concept imagines the S5 packing a lavish unibody aluminium build, which is waterproof and dustproof.
That’s something that’s not totally out of the question in the light of Samsung’s attempt to give the recently launched Note 3 a more premium feel by incorporating a leather back panel. It's also consistent with rumours that metal casings were considered for the S4, before being rejected due to manufacturing issues.
And of course because this is strictly in the realms of fantasy, this handset's spec sheet is wonderfully lavish. Think: 16-megapixel camera with Carl Zeiss optics, a 2GHz Exynos 5 OctaCore processor and Android 4.4 Kit Kat out of the box.
samsung galaxy s5 concept specs
Not enough for you? It's also home to quad-surround speakers, wireless charging and a 3,200mAh Li-ion battery that delivers “50% more battery life than the current Galaxy S4”. With smartphones’ disappointing longevity remaining the industry’s dirty little secret, the latter is something that we'd welcome.
For what it's worth, we really like the design. Not least because it deviates from the big-black-slab school of phone design that's all-too dominant right now. But we want to know what you think. Tell us in the comments section below.

Cancer Patient's Brain Cells Shed Light on How Cancer Spreads

One of the great mysteries of cancer is how it spreads, or metastasizes, throughout the body. But researchers have made an important discovery that may help to solve that puzzle: Cancer cells may fuse with white blood cells in order to spread.
Researchers at Yale University have discovered a metastasis in the brain of a cancer patient that likely grew from the hybrid of a cancer cell and a white blood cell.
The researchers investigated a brain metastasis in a 68-year-old cancer patient who had been treated with a bone marrow transplant from his brother. Bone marrow produces the body's macrophages, a type of white blood cell, and the macrophages from donated bone marrow are genetically distinct from the bone marrow of the person who receives them.
It turned out that the brain metastasis contained genes from both the patient and his brother.
"This tumor was clearly a donor-patient hybrid," said John Pawelek, a cancer biologist at the Yale School of Medicine. "That's really exciting — that's the first proof of cell fusion in human cancer." Pawelek and his colleagues detailed their findings June 26 in the journal PLOS ONE.
These findings could lead to new targets for drugs that could attack such hybrids to prevent the spread of cancers, scientists said.
Most people who succumb to cancer die when it metastasizes — tumors are typically more treatable before they spread. In metastasis, cells somehow acquire the means to break away from their original (primary) tumor, migrate past other cells, travel around the body via blood or lymph vessels, invade tissues and grow in the uncontrolled manner typical of cancers. [Top 10 Cancer-Fighting Foods]
But much remains unknown about what makes a cancer cell metastasize. One popular explanation is that cancer cells in the primary tumor accumulate mutations that help them migrate and invade other tissues. However, one problem with this explanation is that it remains unclear how cancer cells acquire the correct mutations, in the correct order, needed to metastasize successfully, Pawelek said.
An alternative explanation, proposed more than a century ago by German pathologist Otto Aichel, suggests that cancer cells become metastatic after fusing with macrophages. For evidence of this explanation, Pawelek noted that like metastatic cells, macrophages can infiltrate past their neighboring cells and roam the body. In addition, macrophages regularly engulf germs and unhealthy cells. This engulfment includes fusing with unhealthy cells — which suggests some macrophages could fuse with tumor cells instead of destroying them, forming cancer cells that have macrophage traits.
Past research had shown that tumor cells implanted into lab animals could spontaneously fuse with the animal's own cells, and become metastatic. However, attention waned in the fusion theory because scientists could not find a way to detect any such hybrids in human cancer patients — a person's tumor cells and their macrophages would be virtually genetically identical, making it difficult to prove that metastatic cells were hybrids.
If cell fusion turns out to be a major cause of metastasis, "responsible for, who knows, 10 percent to 100 percent of metastases, then these hybrids would be great targets for therapies," Pawelek told LiveScience. "If we could stop metastases by targeting these hybrids, that could help save lives."
Gary Clawson, a pathologist and cancer biologist at Pennsylvania State University, said that while the new results are exciting, they do not conclusively prove that cell fusion leads to metastasis.
Although the cancer in the patient's brain definitely contained hybrid cells, no primary tumor was seen elsewhere, he said. This raises the possibility that this cancer may not have arisen metastatically, arriving from elsewhere in the body. Instead, this cancer may have been a primary tumor that arose from fusions between macrophages andcells in the brain.
Pawelek explained that samples from the rest of the patient's body were not available to the researchers because they had never been surgically removed in the first place, or because the specimens had been reserved for diagnosis by physicians. As such, the researchers had no way to analyze tumors elsewhere in the patient.
Clawson said hybrid cells may play a different role in metastasis: They might alter tumor cells, helping them acquire the ability to migrate, he said.
Clawson also suggested that hybrids may travel around the body and release cancer-triggering molecules, creating sites where metastases could flourish. Metastases could then form when cancer stem cells — cells in tumors thought to have the capability to produce new growths — leave tumors, circulate around the body and colonize the sites that hybrid cells already made vulnerable to cancer. Clawson detailed this idea in the Nov. 8 issue of the journal Science.
However, Pawelek said he finds this explanation unnecessarily complicated. "I think hybrid cells by themselves can circulate, and cause tumors at other sites," he said.

source :

Beyond the Higgs Boson: Five Reasons Physics is Still Interesting (Op-Ed)

This article was originally published at The ConversationThe publication contributed the article to LiveScience's Expert Voices: Op-Ed & Insights.

Would physics be “far more interesting” if the Higgs boson had not been found? Stephen Hawking thinks so. He made this bold claim, possibly with his tongue slightly in his cheek, at the opening of a new exhibition at the Science Museum in London that celebrates particle physics.
With the boson in the can, the Nobel gongs handed out, and the particle collider where it was discovered offline for a two-year upgrade, why are we still doing physics? Here are five possible reasons:

1. Still in the dark

With the discovery of the Higgs, the crucial final piece of physicists’ cosmic jigsaw known as the Standard Model has been put in place. However, there is plenty still to play for in particle physics. For example, we cannot explain why we are here at all. The Standard Model, for all its mathematical elegance and incredible real-life precision, predicts that the universe should just be a sea of cold, lifeless light.

But this exists.
Credit: The Hubble Heritage Team.
When the universe began, there should have been equal quantities of matter and antimatter. Matter and antimatter aren’t happy bedfellows and, on contact, tend to annihilate in a flash of light. Yet, somehow, a little bit of matter was left over, and some of it evolved into beings capable of conscious thought who are currently contemplating how their existence is even possible. What could be more interesting than a gloriously recursive existential crisis?

2. Magnets, how do they work?

The particle physicists may have nailed down the behaviour individual subatomic particles, but the collaborative shenanigans of trillions of particles together in a solid or a liquid still often elude explanation. From semiconductors to magnets, we do know how many materials work. However, there are some exotic substances that we still don’t understand, such as superconductors: how can these weird materials conduct electricity with no loss of energy whatsoever? Currently, superconductors only function when kept at a couple of hundred degrees below freezing. If we could get them working at room temperature, we could ride the wave of technological revolution.
Incidentally, the Higgs mechanism (which gives rise to the eponymous boson) was first postulated by theoretical physicists investigating superconductivity. The same mathematics describes electrons in super-cold lumps of superconducting metal, and the Higgs field which permeates the entire universe and gives all particles its mass.

3. The fastest mirror in the universe

Since physics probes the biggest, smallest, fastest, slowest, coldest and hottest things in the universe, it plays host to some jaw-dropping experiments.
Want to detect neutrinos, the tiniest particles in existence? Deploy a 50,000-tonne tank of ultra-pure water a mile underground in a Japanese zinc mine, surround it with 10,000 ultra-sensitive detectors, and watch for almost-invisible flashes of light. Simple.
Want to double-check Einstein’s theory of relativity? The man himself once devised a thought experiment where you reflect a beam of light off a mirror travelling at a significant fraction of the speed of light. It is a thought experiment no longer: physicists actually did it, bouncing light off a mirror made from electrons travelling at thousands of miles per second. (It worked, and Einstein still seems to be right.)

4. Nuclear fusion

What science other than physics could provide us with the possibility of a near-infinite source of clean energy? In nuclear fusion, the source of power which keeps the stars shining, hydrogen atoms heated to millions of degrees smash together and form helium, releasing vast quantities of delicious energy in the process. Physicists and engineers reckon that, for about the same amount of money budgeted to build Britain’s new high-speed rail project HS2, we could get from today’s experimental fusion reactors to industrial-scale machines delivering electricity to the grid. So, that’s almost unlimited, pollution-free energy, all for around £50 per person in the developed world. So not only is physics interesting, but it’s a bargain too.

5. Space


Credit: NASA/JPL-Caltech/SSI.
This image was taken by Cassini, a robotic probe orbiting Saturn. If the backlit splendour of Saturn’s intricate, sparkling ring system isn’t enough for you, the pale blue dot in the bottom right of the image is none other than us: planet Earth, staring back.
There is so much of our Universe left to explore, whether by spaceship or telescope, whether lakes of liquid methane on moons within our solar system, or planets orbiting distant stars in solar systems of their own.
Indeed, in Hawking’s own words:
Remember to look up at the stars and not down at your feet. Try to make sense of what you see and hold on to that child-like wonder about what makes the universe exist.
Maybe he is not so cross about the yawn-inducing Higgs disappointment after all?
Andrew Steele does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.
This article was originally published at The Conversation. Read theoriginal article. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on LiveScience.