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Odd states of matter: how three British theorists scooped the 2016 Nobel Prize for Physics

Physics

Odd states of matter: how three British theorists scooped the 2016 Nobel Prize for Physics

Posted By liveworld

The ConversationThe Nobel Prize in Physics for 2016 has been awarded to three British scientists working in the US for their theoretical work explaining strange states of matter, including superconductors, superfluids and thin magnetic films.

The prize was split between David J Thouless of the University of Washington, Duncan M Haldane of Princeton and J Michael Kosterlitz of Brown University. They will share a sum of US$928,000. Their work has helped shape an enormous amount of research over the past three decades and this well-deserved prize reflects the continuing importance of new discoveries that have and will continue to emerge from it.

“Normal” states of matter are ones you’re likely familiar with: solids, liquids and gases. The transition between these states is characterised by what is referred to as “symmetry breaking”.

For example, in a liquid, atoms are arranged uniformly in space and it looks identical no matter how you rotate it. However, when a liquid turns into a solid the atoms are locked into a crystal lattice. This new state of matter is less symmetrical in the sense that it only looks the same if it is rotated at certain angles. However, Thouless, Haldane and Kosterlitz found that matter is a lot more interesting than this. Their work showed how new phases of matter can occur where no symmetry is broken – and they used a mathematical idea to explain this. What distinguished these phases of matter – which display strange behaviour such as unusual patterns of electrical conductivity – were “topological properties”.

Topology is the mathematical study of how surfaces can be deformed continuously and smoothly. A famous example is the surface of an orange, a croissant, a coffee cup and a doughnut. To a mathematician, all these objects are imagined to be made of a malleable material that we are allowed to deform continuously without cutting or tearing. In this way an orange and croissant are identical, since we could mould both of them into a sphere. Likewise the coffee cup and doughnut are also the same to a mathematician because they both have one hole – the cup has a hole in its handle and the doughnut at its centre.

So, in this abstract sense the orange and croissant are in one distinct class, while the coffee cup and doughnut are in another. The difference between them boils down to whether their surface has a hole in it or not. This is the topological property of the object that is robust to any form of moulding we might do. The work of Thouless, Kosterlitz and Haldane made important steps in understanding how the notion of topology plays a role in the phases of matter.

This connection was exposed by considering the energies that electrons in materials can occupy – which can be plotted as a surface (when presented as a function of their momentum). In the 1980s scientists discovered that electrons in certain two-dimensional thin films move in a strange way when subjected to a strong magnetic field. These electrons order into perfectly conducting channels, located at the edge of the material, based on a quantum mechanical property known as spin.

What’s more, this conductivity increases in discrete steps as the magnetic field increases – an effect called the quantum Hall effect. Thouless and coworkers found that the “energy surface” for these materials could be described as a doughnut in topological terms, and the channels of energy that were seen were effectively the number of holes in that surface. Along with further work by Kosterlitz and Haldane on other systems, like vortices superconductors and hidden ordering in magnetic materials, their work demonstrated that the idea of topology could be used to predict the behaviour of solids.

Great promise

Thouless, Kosterlitz and Haldane’s work has laid the foundations for new emerging fields. In particular they have been crucial to an area of solid state physics called topological insulator materials. These are new three-dimensional materials that carry electricity on the surface but not in their interior. Their energy surface can also be described by topology. These materials have many “spintronic applications”, and heads of hard drives based on this technology are currently used in industry.

Technological applications of materials often rely on how they behave when they are “excited” as a result of some energy transfer. We can imagine an excitation as being a bit like a pulse travelling down a string if we shake it at one end.

One device that is currently being studied is made of topological insulator layered on top of a superconductor (a material with zero electrical resistance at low temperatures). If we poke this system in the right way then it is excited at the interface between the materials. These excitations carry a topological property, like a hole in a doughnut, which is robust to noise and imperfections that might scatter the excitation (which could be some sort of signal).

This effect is potentially very useful for quantum computing. The “bits” of data in a normal computer are 1 or 0. However a quantum computer uses quantum bits, which can be in superpositions of states (according to quantum mechanics) – making calculations super fast. Currently scaling quantum computing up to commercially applicable sizes is hampered by noise from the external environment, such as something shaking. However, by exploiting excitations of topological materials, the information encoded in them could be protected and preserved.

This is an exciting avenue of research that could help revolutionise information processing technologies.

 

Stephen Clark, Lecturer in Physics, University of Bath

This article was originally published on The Conversation. Read the original article.

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High blood pressure may protect over-80s from dementia

Health and Medicine

High blood pressure may protect over-80s from dementia

Posted By liveworld

The ConversationIt is well known that high blood pressure is a risk factor for dementia, so the results of a new study from the University of California, Irvine, are quite surprising. The researchers found that people who developed high blood pressure between the ages of 80-89 are less likely to develop Alzheimer’s disease (the most common form of dementia) over the next three years than people of the same age with normal blood pressure.

Blood pressure is an approximate measure of how hard the heart has to work to pump blood around the body. As blood pressure increases, so too does the effort of the heart. Over time, the added strain caused by high blood pressure can damage the heart and increase the risk of having a heart attack. High blood pressure can also indicate that the blood vessels are themselves damaged or blocked. This is particularly bad for the brain, because it needs a lot of energy and is highly dependent on a constant supply of oxygen and nutrients that are carried by the blood. In extreme cases, a lack of blood supply in the brain can result in a stroke and vascular dementia.

Damage to blood vessels in the brain is also implicated in the development of Alzheimer’s disease. In addition to delivering oxygen and nutrients, the blood vessels in the brain also act to remove waste products, such as the β-amyloid protein, from the brain. Dysfunction of the vessels can lead to an accumulation of β-amyloid and other toxic proteins in the brain, ultimately leading to death of brain cells and dementia.

It is thought that having high blood pressure increases the risk of developing Alzheimer’s disease. Several long-term studies that have followed people from middle to old age have found that people who have high blood pressure in their 40s and 50s are more likely to develop Alzheimer’s disease in old age compared with those who have normal blood pressure in midlife. Although the definitive reasons for this increased susceptibility are not known, they may relate to damage to the structure of the blood vessels, decreased blood flow to the brain and impaired clearance of toxins from the brain.

However, this latest study from UC Irvine, suggests that having high blood pressure – at least at a certain age – actually protects some people from developing Alzheimer’s disease.

So, how can these apparently contradictory findings be reconciled? The answer may relate to how blood pressure changes normally across the lifespan. As we age, our bodies become less able to compensate for fluctuations in blood pressure, such as when standing from a sitting position.

High blood pressure may help eliminate waste from the brain. SpeedKingz/Shutterstock.com

About 30% of people over 70 years of age experience a feeling of dizziness, light-headedness or weakness when going from sitting to standing (termed postural hypotension). This occurs because of a drop in the amount of blood getting to the brain. In fact, postural hypotension is itself associated with increased risk of developing Alzheimer’s disease. So, people who develop hypertension in late life may do so to compensate for an age-related decrease in blood pressure. This may help them maintain an adequate blood flow to the brain, facilitate waste removal and ultimately protect the brain cells. Alternatively, in people who do not develop Alzheimer’s disease until 90 years of age, or older, changes in blood pressure may occur alongside the onset of dementia, rather than contribute to disease onset.

Increasingly, research points to a role for blood vessels and factors that affect the health of the blood vessels in Alzheimer’s disease. Based on the current understanding, maintaining blood pressure within the “Goldilocks range” – not too high, not too low – is still the best course of action for reducing the risk of developing Alzheimer’s disease.

 

Cheryl Hawkes, Lecturer in Health Sciences, The Open University

This article was originally published on The Conversation. Read the original article.

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Why is the norovirus such a huge problem for the NHS?

Health and Medicine

Why is the norovirus such a huge problem for the NHS?

Posted By liveworld

The ConversationNorovirus, also known as winter vomiting disease, is on the rise again according to a report in the BMJ. A familiar set of warnings about ward closures and avoiding visits to patients in hospital was also issued, but why does this one virus cause the NHS such difficulty?

While norovirus does occur year-round, there is a winter peak in cases that clashes with the winter rush on the NHS. The symptoms of norovirus – diarrhoea and vomiting – typically last a day or two. While you may spend those days wishing you were dead, the chances of long-term harm from the infection are extremely low if you are otherwise healthy. The people most at risk from norovirus are the very young, the elderly and people with impaired immune systems (those said to be immunocompromised). Unfortunately, these are exactly the groups most likely to find themselves in hospital.

As a result of advances in transplant medicine and cancer treatment that suppress or affect the immune system, these immunocompromised patients make up an increasingly large portion of the population. While norovirus only lasts a few days at most in healthy people, those who are immunocompromised can struggle to clear the infection; it can linger for weeks, months or even years. Fortunately, it is rare that full-blown norovirus symptoms are experienced for this long. It does make it hard to absorb food and gain weight, which is a worry after major surgery and can make recovery much more difficult. As such these patients are a particular concern.

It is very easy to pass on the norovirus. One tablespoon of diarrhoea from a single patient can contain enough infectious virus to infect everyone in the world many times over. To make things worse, like many other viruses, people may remain infectious for several days after symptoms have resolved and not every infected person may even be symptomatic. Many cases are traced back to food handlers who may appear well and have no idea they are infectious. The virus can be spread through touching infected surfaces or material and a lack of suitable handwashing or hygiene before.

Norovirus is often passed on by people handling food. Juan Gaertner/Shutterstock.com

Outbreaks tend to occur in closed environments such as hospitals, cruise ships, schools and retirement homes, as these all share common dining and social areas and have many people eating food prepared by others. In the case of hospitals, many of these have a food court or canteen which is shared by staff, patients and visitors. In summer, many escape outdoors on lunch breaks to enjoy the weather. But in winter when norovirus peaks, everyone crowds together inside, away from the cold.

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What Would Happen If Every Single Nuke In The World Went Off At The Same Time?

Physics

What Would Happen If Every Single Nuke In The World Went Off At The Same Time?

Posted By liveworld

Have any of you seen the movie Dr. Strangelove (Or How I Learned To Stop Worrying And Love The Bomb)? It’s a classic film, one that satirizes the nuclear arms race in the Cold War. Spoiler alert: A chain of unfortunate events ends up causing every single nuclear weapon around the world to detonate, leaving humanity pretty screwed.

With Trump’s recent and terrifying comments about boosting the US nuclear arsenal and not ruling out using any of these weapons in the Middle East or Europe, we felt it best to work out – for your horror – what would happen in the event of a nuclear apocalypse. What would happen if every nuclear weapon in the world today was fired and detonated?

In short, nothing good. Here’s the rather grim mathematics and science behind the end of the world.

From Russia With Love

No fighting in the war room. liberalartist6 via YouTube

First, let’s have a look at what various countries have in their nuclear arsenal.

As per the Federation of American Scientists’ 2017 data, there are 14,900 nuclear warheads in the world. The US has 6,800 and Russia 7,000, making up the vast majority of the world’s city killers. The UK has 215, France 300, China 260, India 120, Pakistan 130, Israel about 80, and North Korea roughly 10.

The yields of each of these vary considerably. The US and Russia, for example, have hyper-powerful thermonuclear weapons, whereas North Korea can barely get past an old-school plutonium fission-style device.

One of the most powerful weapons in the US arsenal is the B83, which has an explosive yield equivalent to 1.2 megatons of TNT. This equates to about 5 quadrillion joules of energy, or 5 Petajoules – or 79 Hiroshima “Little Boy” atomic bombs’ worth of energy.

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Ultrafast Camera Caught Light Doing A “Sonic Boom”

Physics

Ultrafast Camera Caught Light Doing A “Sonic Boom”

Posted By liveworld

For the first time, an international group of scientists has managed to film light pulses forming a photonic Mach cone, the equivalent of a sonic boom but for light. The incredible feat was only possible thanks to an experimental camera that is capable of capturing 100 billion frames per second.

The Mach cone is created when a wave emitter moves faster than those waves. Supersonic jets routinely form these cones, but when it comes to light, things get a bit more complicated. Obviously, nothing moves faster than light in a vacuum, but light moves slower in other materials and that’s where these elusive phenomena can be studied.

The team, led by Dr Jinyang Liang and Dr Lihong Wang, shot brief laser pulses through a “source tunnel” sandwiched between two materials through which light would move more slowly. As the light goes through the tunnel, the pulses are scattered, creating wavelets that move at a superluminal speed.

The camera recorded a Mach cone that matches the theoretical predictions for it, with the results published in Science Advances. The superluminal pulse forms a triangular region that is dragged ahead across the material. When the same experiment was repeated with a subluminal pulse, no such pattern was visible.

Subluminal (top) and superluminal (pulse) being propagated in the source tunnel. The superluminal shows a clear Mach cone. Jinyang Liang and Lihong V. Wang

“We made the first-ever video recording of a propagating light-induced photonic Mach cone in real time,” Dr. Liang told IFLScience. “This dynamic light scattering event was captured in a single camera exposure by the newly developed single-shot lossless-encoding compressed ultrafast photography (LLE-CUP) at 100 billion frames per second.”

To snap such a fleeting event, the team had to design not only the experiment but also the camera, which was purposely constructed to record it. The LLE-CUP uses a three-in-one recording system. One channel works very much like a regular camera, while the other two record temporal information of the dynamic event. Combined together, they produce this incredible view on the phenomenon.

This observation might seem far removed from applied physics, but the technology could be used in many different applications, including observing neurons firing up and imaging how microstructures in living tissues change.

“We envision that the LLE-CUP technology will find widespread applications in both fundamental and applied sciences,” Liang added. “Our camera is fast enough to watch neurons fire and image the ‘live traffic’ in the brain. We hope we can use our system to study neural networks to understand how the brain works.”

 

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Trump Administration Removes All References To Climate Change From White House Website

Environment

Trump Administration Removes All References To Climate Change From White House Website

Posted By liveworld

“The requested page “/energy/climate-change” could not be found.”

The instant President Trump took the oath of office on Friday, an information page about climate change on the White House website was deleted. 

Instead, a site called “America First Energy Plan” claims that the Climate Action Plan and the Waters of the US rule – designed specifically to protect American water bodies – is detrimental to society. The aim of the Climate Action Plan is to reduce greenhouse gas emissions and combat climate change.

“For too long, we’ve been held back by burdensome regulations on our energy industry,” the page says. “President Trump is committed to eliminating harmful and unnecessary policies such as the Climate Action Plan and the Waters of the U.S. rule.”

To make matters worse, it continues with: “The Trump Administration will embrace the shale oil and gas revolution to bring jobs and prosperity to millions of Americans.”

Except, you know, a recent report just found that the renewable energy sector employs more people than oil, coal, and gas combined in the US.

In typical-Trump style, though, he has refuted evidence for backward logic, denying what a vast majority of scientists have found after years of detailed work and study. 

This is what the site looked like on Thursday, January 19:

content-1484941882-1484936931-20170120-w

Courtesy of the Internet Archive’s Wayback Machine

As is well known, 44th President Barack Obama has been an avid advocate of reducing greenhouse gas emissions, most notably signing the Paris Agreement. Unfortunately, the upcoming forecast for climate change research and mitigation in the US looks grim. 

This is what the scrubbed site now looks like:

content-1484942503-1484933679910936.jpg

 

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NASA Video Shows What It Would Be Like To Land On Pluto

Space

NASA Video Shows What It Would Be Like To Land On Pluto

Posted By liveworld

What would it be like to land on Pluto? We might not know any time soon, but thanks to a new NASA video, we can get a pretty good idea.

Released yesterday, the movie stitches together 100 images taken by NASA’s New Horizons spacecraft as it approached Pluto in July 2015. The images begin from a distance, showing Pluto and its moon Charon, before “landing” on a shoreline of a region rich in nitrogen ice.

The image is a color version of one released by NASA last year, giving us a better glimpse at what it would be like to approach and touch down on Pluto. Color was added by the Ralph color camera aboard New Horizons, giving the best simulation of what the surface looks like.

It took New Horizons more than nine years to reach Pluto, traveling 3 billion miles (4.8 billion kilometers) in the process. Now, it is on its way out of the Solar System, and on its way to visit an object in the Kuiper Belt on January 1, 2019.

Until then, let’s remember that incredible flyby of Pluto on July 14, 2015. Check out the video below.

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Well-Meaning New Zealander's Are Killing Endangered Birds By Accident

Plants and Animals

Well-Meaning New Zealander's Are Killing Endangered Birds By Accident

Posted By liveworld

Well-meaning residents of New Zealand’s capital may be killing the city’s endangered birds with kindness. It turns out that the chicks of the kākā birds that live in Wellington are failing to survive because locals are feeding the parents the wrong type of food.

An urban ecology team for Wellington have been keeping track of the birds that live in the parks and reserves surrounding the city, and found that last year 80 percent of the chicks failed to make it to adulthood. Investigating this devastating survival rate, they found that residents feeding the adults food such as nuts, seeds, and bread, which then go on to regurgitate it for their offspring, is causing the chicks to develop metabolic bone disease.

This causes problems with the strength of the bones in developing birds. Some kākā have been found to grow up with deformed limbs and bone abnormalities, including beaks that struggle to close. It is thought that even if the chicks do survive to adulthood, their bones are so weak that the slightest of knocks can cause them to shatter.

“Last year we did autopsies on kaka chicks we found dead and in a number of them we found nearly every bone in their body had fractured because of the disease,” the council’s urban ecology team leader Myfanwy Emeny told the Guardian. “The saddest thing about this condition is it is a preventable disease. People just love the birds, they are trying to do the right thing by feeding the parents but it is resulting in this horrible condition in the chicks.”

The birds are a type of large parrot that are native to the islands, but have been decimated in numbers in recent times. Usually found living in the forests, the kākā have declined greatly due to habitat loss, invasive predators, and competition with wasps and bees. The introduced stoats are known to predate on nesting females as they incubate their eggs, while breeding birds are being outcompeted by wasps in the collection of a vital food source: honeydew.

This is not the only example of people trying to do good by feeding wild birds but instead inadvertently harming them. Angel wing is a condition that can afflict ducks and geese that are fed a diet too high in bread, causing the wings of developing chicks to grow to such an extent that they are not able to fly.

The urban ecology team recommend that rather than feeding the kākā nuts and bread, residents should instead plant native trees and shrubs, in addition to providing drinking water. They say that there is plenty of natural food in the surrounding parks to keep the birds sustained.

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How We Are Listening To The Universe

Space

How We Are Listening To The Universe

Posted By liveworld

The old adage, courtesy of Ridley Scott, is that in space nobody can hear you scream. But in reality, what you can or cannot hear in space is all a matter of technology.

Sound is a mechanical wave: To propagate it requires a material and it cannot spread through a vacuum. And while space is very empty, it is not exactly a vacuum. The universe is filled with particles. Yes, there are huge swathes of space with less than half a proton per cubic meter, but planetary systems and nebulae are denser and they do transmit sounds.

Those sounds are not audible within the limited range of the human ear, but they can be measured and converted into something we can all listen to.

Among the famous (and somewhat terrifying) sounds of space, a spot of honor belongs to the Voyager recording of interstellar plasma waves. The recording is 12 seconds long and incredibly significant. We have sent a man-made object, the Voyager 2, so far away from our planet that it is now capable of detecting waves of particles in interstellar space.

Mechanical waves play an important role in star formation. The collapse of gas into a star depends on the speed of sound. And even the beautiful structures seen in supernova remnants have a sound connection. The material the star ejects moves at supersonic speeds and slams into the interstellar medium, heating it up to millions of degrees, eventually forming spectacles like the Crab Nebula.

Scientists also enjoy making audible what’s not normally in that form. Radio waves are a good example of this. Scientists take the frequency of the radio signal (from 300 GHz to 3kHz) and convert them into sounds (with shifted frequency, 20 kHz to 20 Hz). So, although radio waves are just a type of light, it’s more effective to hear them as sound than to see a radio map of a source. You can listen to the sound of radio communication on Earth, to the lightning on Jupiter, and even the radio emission of Saturn.

But it’s not just radio waves. Any kind of wave can be converted into sound. Physicists have even turned the signal of gravitational waves detected last year into a nice chirp. And the sounds are not just used for science – these cosmic noises are even used for art. Queen Mary University is currently running a short-film competition on space sounds.

Sometimes it’s for fun and other times because it’s useful. We rely heavily on our hearing, and thanks to millennia of music, we are good with tunes and patterns. By listening, we might pick up on something not easily seen in the data. And with the right tech, we can listen to the music of spacetime itself.

 

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How "Star In A Jar" Technology Could Change Our World Forever

Space

How "Star In A Jar" Technology Could Change Our World Forever

Posted By liveworld

Inside our Sun, hydrogen is constantly being converted into helium, producing a tremendous amount of energy – enough to heat the planets, melt comets, and support life on Earth. So it’d be pretty good if we could replicate that process on our own planet, right?

That’s what scientists have been trying to do for decades now. Nuclear fusion, also known as “star in a jar” technology, has seemingly always been on the horizon but never quite within reach. A number of recent breakthroughs, however, suggest we may soon be mimicking the power of the Sun on Earth.

One of the most recent breakthroughs was made using Germany’s Wendelstein 7-X (W7-X) fusion device. In early December 2016, scientists at the Max Planck Institute in Greifswald managed to sustain a hydrogen plasma in the experimental reactor for a few milliseconds.

It may not sound like a big deal, but this was hugely significant for a number of reasons. First, to kickstart nuclear fusion, extremely high temperatures – about 100 million °C (180 million °F) – are required to make a plasma cloud. This cloud must also be confined by extremely powerful magnets so that it does not touch the cold walls of the reactor.

Second, this process had only previously been achieved with a helium plasma. Hydrogen fusion provides much more energy, so is much more desirable. Just getting to this stage at all at the W7-X has taken 19 years and cost $1.1 billion.

The W-7X is a type of fusion reactor known as a stellarator, which is shaped like a twisted donut to keep the plasma confined, by twisting the magnetic fields around it. Another type of fusion reactor, known as a tokamak, achieves this twisted magnetic field in a different way. They are more regularly shaped donuts, but use a large current to achieve the same twisting effect in the plasma. Both methods have their advantages and disadvantages.

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