Does the brain awaken via a continuous phase transition?

23 May 2019 Hamish Johnston

Critical awakening: physicists have found evidence of a continuous phase transition in brain activity. (Courtesy: Shutterstock/Phonlamai-Photo)

Further evidence that the brain undergoes a continuous phase transition when we awaken from sleep has been discovered by physicists in Brazil. The team studied patterns in the spiking of neurons in the brains of sleeping and awake rats and found evidence for a critical point where the transition occurs.

An important unanswered question is how the brain makes the transition between these two different states – or phases – of consciousness. One possibility is that brain activity undergoes a continuous phase transition. This process occurs in a wide range of physical systems including the transition between the magnetic and non-magnetic phases of iron when the material is heated above a critical temperatureWaking up in the morning certainly feels like a transition between two states of mind, but scientists do not have a good understanding of how the brain shifts from one state to the other. Researchers do know that brain activity involves neurons creating small voltage spikes. By studying these spikes in mammals, scientists know that the spikes are emitted in synchronous repeated bursts during sleep and as asynchronous noise-like signals when the animals are awake.

Batteries for electric vehicles, advances in radiotherapy, squid-inspired blankets

09 May 2019 Hamish Johnston

In this episode of the Physics World Weekly podcast, Anna Demming reports back from an event at the Society for Chemical Industry in London that focused on developing a supply chain in the UK for manufacturing the batteries that will be needed to create fleets of electric vehicles.

Tami Freeman talks about her visit to the European Society for Radiotherapy and Oncology in Milan, where she discovered what medical physicists think will be the most important issue for training new colleagues ten years from now.

James Dacey is also on hand to explain how the skin of a squid has inspired a new type of space blanket.

Hamish Johnston is the general-physics editor of Physics World

As quantum technology matures what industries should care?

24 May 2019 Anna Demming

Industry gets entangled: Quantum technologies are coming so who should wake up and smell the coffee? Credit: iStock Traffic-Analyzer

“In the next 5-10 years a quantum computer will do a calculation that a supercomputer can’t do,” Rupesh Srivastava told around 65 invited attendees at the OxLEP led Quantum Technologies briefing at the UK’s House of Commons. No-one can predict the future, but as a Technology Associate at Oxford University’s Clarendon Laboratory working for Networked Quantum Information Technologies (NQIT) Srivistava is well placed for an educated guess, and there is increasing confidence that in the not so distant future, quantum phenomena will descend from the lofty realms of the wacky and inscrutable to be harnessed in technologies that are useful and eventually indispensable for human activities. However as to what those activities are and who should care, it seems the jury is still out.

Battle of the elements: what makes carbon King of the Elements?

24 May 2019 Anna Demming

Which is your favourite chemical element? To mark the International Year of the Periodic Table, our science journalists will be arguing for their pick from the 118 known elements. In this instalment, Anna Demming argues the case for carbon as a fundamental building block of life and chemistry, and the new science that has emerged from carbon nanomaterials.(Adapted from shutterstock/agsandrew)

What links the Earth and the air? What both sparkles like starlight and reflects almost nothing at all? What underpins the chemistry of biological molecules – life itself – and has launched a whole field of materials science in 2D, not to mention its mechanical, electrical and optical properties, which are worth (to funders at least) billions? In some form or another carbon and carbon compounds take a piece of the action in almost all fields of science.

So what makes carbon so ubiquitous in so many fields? A chemist might think a good place to start is by looking at how carbon bonds to other elements. As a physicist by training, though, I’d add that where it gets really interesting is explained by physics.

Metal organic frameworks stiffen up for improved CO2 capture

23 May 2019 Henry R N B Enninful

Rapid heat treatment could help MOFs capture the CO2 released into the atmosphere through industrial and everyday human activities. (Credit: iStock/BM Noskowski)

Roasting metal organic frameworks (MOFs) could make them more effective at capturing CO2to remove a key greenhouse gas from the atmosphere, according to recent research by Kumar Varoon Agrawal and co-workers at the École Polytechnique Fédérale de Lausanne. Reporting in Advanced Materials, they show that heating a membrane of zeolitic imidazolate framework 8 (ZIF-8) to an optimum temperature of about 360°C for about 3 to 5 seconds – what they describe as rapid heat treatment (RHT) – could lead to more selective CO2 capture.

Metal organic frameworks (MOFs)

Polycrystalline MOFs are a class of compounds consisting of metal ions or clusters linked together by organic ligands to form one-, two-, or three-dimensional porous structures. They have applications in a wide range of fields ranging from catalysis, gas storage, biological sensing and imaging, and drug delivery stems, among others.

Magnetic beads help treat preeclampsia

21 May 2019 Belle Dumé

Blood pressure check. Copyright: American Heart Association

Roughly one in 20 women develops preeclampsia during pregnancy, a high blood pressure condition that can be life-threatening to both mother and baby. The disease is characterized by a massive increase in sFlt-1 (the soluble form of the vascular endothelial growth factor 1), which is released by the placenta into the maternal bloodstream. It is this growth factor that causes blood vessel wall dysfunction by binding two important angiogenic molecules that are responsible for maintaining healthy blood vessel walls. These molecules are endogenous PIGF (placental growth factor) and VEGF (vascular endothelial growth factor).

Terahertz light pulses speed up spin switching

22 May 2019 Belle Dumé

Achieving material magnetization switching on the shortest timescales, at a minimal energy cost. CREDIT: @tsarcyanide/MIPT Press Office

A new technique to rapidly reverse a magnet’s polarity in a way that all of its spins coherently rotate could be used to develop more energy-efficient data storage devices and superfast computers in the future. The technique, which works by applying ultrashort pulses of terahertz-frequency light to the magnet, does not produce any waste heat and requires very little energy – just one photon per spin flip.

Modern-day computer hard drives encode data as binary zeros and ones by orienting the spins in magnetic materials using magnetic field pulses created by an electrical current. This process dissipates huge amounts of energy though (and is relatively slow). Indeed, today’s data centres consume between 2 and 5% of the world’s electricity and produce waste heat that, in turn, requires even more power, to cool the servers down.

Atom patterning breaks new number record

24 May 2019 Belle Dumé

Defect-free pattern of 100 atomic qubits: a new platform for scalable quantum computing. Credit: Gerhard Birkl

Neutral atoms trapped by light in arrays of dipole traps could be used as quantum bits for quantum computing. For such applications, however, these atoms must be positioned individually within the traps to create defect-free arrays that can then be used in information processing. Researchers at the Technische Universität Darmstadt in Germany have now developed a new technique for patterning 111 atoms in this way, so breaking the previous record, set last year, of 72 atoms. The method should even be scalable to one million atoms or more, they say.

In their experiments, the researchers, led by Gerhard Birkl, began by creating a cloud of several million rubidium atoms in a room-temperature vacuum system using a magneto-optical trap. They then cooled the atoms down to around 100 microKelvin and transferred these atoms into a microtrap array, which consists of hundreds of laser traps arranged in a square lattice. They made this lattice by directing a laser beam through an array of commercially-available microlenses.

Condensing droplets get a boost from micron-thin polymer coating

25 May 2019

Drip feed: droplets of a low-surface-tension fluid forming on the surface of a pipe treated by iCVD. (Courtesy: K Varanasi and collegues/MIT)

A new surface coating that could boost the efficiency of refrigerators and other industrial systems that rely on condensers has been developed by Kripa Varanasi and colleagues at the Massachusetts Institute of Technology. The thin polymer layer can be deposited on a range of different surface shapes and materials to enhance the formation and shedding of low-surface-tension droplets. Their discovery could ultimately increase the efficiency of a wide variety of large-scale industrial processes by almost 2%, creating a significant dent in their greenhouse gas emissions.

Condensation plays an important role in many large-scale industrial processes including refrigeration, liquification, waste heat recovery and distillation. Unlike water vapour, which condenses on a cold surface producing droplets that coalesce and quickly drip away, many industrial substances (such as ethanol and hexane) have a much lower surface tension. Instead of forming droplets, these liquids will spread out across the surface of a condenser in a process called wetting. This forms an insulating layer that limits heat transfer and therefore inhibits the operation of the condenser.

Single-atom imaging could help search for neutrinoless double beta decay

09 May 2019

Neutrino-free process: observing neutrinoless double beta decay could shed light on important mysteries of particle physics.

A new technique to enable the detection of a hypothetical process called neutrinoless double beta decay has been developed by an international team of physicists. Their technique involves probing a large sample of xenon for nuclei created by the decay process. If neutrinoless double beta decay is indeed spotted, it could have profound consequences for our understanding of the universe.

Beta decay covers a family of processes that involve the emission of neutrinos (or antineutrinos) by a nucleus. One common beta-decay process involves a neutron in a nucleus transforming to a proton by the emission of an electron and an electron antineutrino. If neutrinos are there own antiparticles, the emitted electron antineutrino can then be absorbed as a neutrino by another neutron in the nucleus – leading to a second beta-decay and emission of another electron.

European physicists look to the future of particle colliders

16 May 2019 Hamish Johnston

Put a ring on it: the Future Circular Collider could be built under Lake Geneva. (Courtesy: CERN)

Hundreds of physicists from Europe and beyond have met in Granada, Spain to develop a plan for a next-generation collider that will eventually supersede the Large Hadron Collider (LHC) at CERN. While no decisions were taken about specific collider technologies at the open symposium of the European Strategy for Particle Physics, the 600 participants had their say on the important physics questions that need to be addressed by future collider facilities.

Fabiola Gianotti, director-general of CERN, said she received two main messages from the meeting. “Number one is that the particle-physics community is incredibly productive,” she said. “It’s amazing to see how much we have done since the last European Strategy for Particle Physics in 2013. The second message is there is an incredible amount of ideas.” Among the many “interesting questions” that she said Europe needed to address were the Higgs boson, dark matter and the “flavour problem”.