Cine-MRI tracks heart motion

MPWJon Cartwright

Researchers in France and China have adapted a technique from video processing in computer vision to study regional motion in cine-MRI. The technique, which involves the extraction of intensity parameters such as local magnitude, phase and orientation, could help in the diagnosis of patients with heart failure (Phys. Med. Biol.61 8640).

Regular MRI allows clinicians to observe tissue inside the body, but as it does not record information in real time it is poorly suited to study moving organs, such as the heart. To get around this limitation, cine-MRI takes sequential images of the heart during the cardiac cycle using an electrocardiogram as a trigger; the patient is also asked to hold his or her breath so that additional movement is not generated by inhaling or exhaling. The result is a two-dimensional film of a slice of the heart during a beating cycle. […]

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Warming has little effect on maize yields

Energy & EnvironmentJon Cartwright

High temperatures are not a sizeable direct cause of lowered maize yields, but a lack of water is. That’s the conclusion of a US study that attempted to disentangle the effects of temperature and water stress in previously reported yield losses.

“Our study indicates that so long as the crop had sufficient water, the high air temperatures experienced during the study period were not reducing maize yields,” said Elizabeth Carter of Cornell University, US.

More maize is produced than any other crop worldwide, and demand is expected to rise in the developing world by 50% by the middle of the century. Over the same period, average global temperatures are expected to increase by some 2°C. […]

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Waking up to the cosmic dawn

HorizonJon Cartwright

Across Europe, some 10 000 antennas stand courtly, like squat flag poles. They may not look like much, but they are in a sense an incredibly powerful time machine.
Known collectively as the Low-Frequency Array (LOFAR), the antennas are receiving radio signals that have travelled billions of years to get here, from the depths of the cosmos. That means they are looking billions of years into the past, when the universe was almost featureless – and when planets, stars or galaxies didn’t exist.

Because light travels at a finite speed, all telescopes look into the past to some extent. But astrophysicist Professor Dominik Schwarz of Bielefeld University in Germany, who helped to plan the telescope, said the ‘cosmic dawn cannot be seen with any other instrument’. […]

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Crossing Europe on the hydrogen highway

HorizonJon Cartwright

From Bergen in Norway to Bolzano in Italy, specialised refuelling stations mean that drivers of hydrogen-powered cars can now travel right across Europe.
Hyundai, Toyota and Honda have all developed – and commercialised – cars powered by hydrogen gas. While there are just a handful on Europe’s roads at the moment, that’s all about to change because of a concerted effort to put hydrogen technology into the fast lane.

Hydrogen works in a ‘fuel cell’ to generate electricity, which can drive a car’s wheels via an electric motor, emitting nothing but water vapour in the process.

‘Our activities aim to improve accessibility and interoperability of stations,’ explained Dolly Oladini, the assistant project manager for HyFIVE, one of a group of research projects that are working collectively to deploy thousands of hydrogen vehicles across Europe, and set up dozens of refuelling stations. […]

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Traded water pollution rising faster than total footprint

Energy & EnvironmentJon Cartwright

Globalization is the driving force behind a thriving “virtual trade” in grey water – fresh water needed to dilute pollution to local standards – according to researchers in China.

Grey water embodied in global imports and exports has risen faster than the world’s overall grey water footprint, the team found. From 1995 to 2009, the EU and US effectively outsourced water pollution by importing goods requiring lots of grey water. Meanwhile, China in particular suffered from water scarcity by generating pollution in the production of goods for export.

The researchers believe that more attention should be paid to virtual trades in grey water. “It’s important to focus on the water scarcity caused not only by the decrease of quantity, but also by the degradation of quality,” said Can Wang of Tsinghua University in Beijing. “International transfers of embodied pollution through bilateral trade, driven by globalization, could aggravate the uneven distribution of water resources on the planet.” […]

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Going clean

New ScientistJon Cartwright

Crack a simple chemical reaction and we don’t have to kick our addition to fossil fuels

SCARRED landscapes, billowing smoke, seabirds wrinsc_20161008-800x1052thing in liquorice gloop: there’s no denying fossil fuels have an image problem. That’s before we even start to factor in the grave risk continuing to burn them poses to Earth’s climate. But what’s the alternative? Nuclear is expensive, renewables are unreliable, and we are a long way from making batteries that could power our fuel-hungry lifestyles. Realistically, we are going to be reliant on fossil fuels for a while yet.

What we need is a way to exploit them without emitting any planet-warming carbon dioxide. Alberto Abánades thinks he has the answer. He isn’t a PR man for the fossil fuel industry, and nor does he have anything to do with various schemes to capture and bury carbon emissions after the event. He and his research team think they have cracked the problem using chemistry alone. By simply changing the way we liberate the energy trapped inside natural gas molecules, we can have all the benefits of fossil fuels – and none of the guilt. Too good to be true? […]

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The descent of mass

Physics WorldJon Cartwright

The simultaneous drop of two dissimilar masses is one of the oldest experimental results. But new techniques may show that not everything falls the same way

pwoct16cover-200What goes up must come down. But does everything come back down at the same time? Galileo said yes. Newton said yes. Einstein said yes. Still, many physicists today secretly believe the answer might be no.

That belief might seem strange. Countless experiments over the years have concluded that two objects dropped from a height will – regardless of their composition – fall to the ground at precisely the same moment, provided they do not suffer disparities in air resistance. Schoolchildren are routinely taught about this “universality of free fall”, often with reference to the famous 1971 video of the US astronaut David Scott standing on the Moon and demonstrating that, in the absence of any air, even a feather and a hammer fall in unison. If the universality is not clear from everyday experience, it is at least implied by Newton’s laws of motion and gravitation, which combine to suggest that the acceleration of a body due to gravity is proportional only to the mass of the planetary object it is being attracted to, not to its own mass. The conclusion would appear irrefutable.

Yet, some violation of the universality of free fall could come in very useful. One of the greatest obstacles to progress in physics is the gaping chasm between the classical world of Einstein’s gen- eral theory of relativity, our current best theory of gravity, and the fuzzy, largely microscopic world of quantum mechanics, which accurately describes the other three known forces of nature: electromag- netism; and the strong and weak nuclear forces. A bridge between the two worlds – a quantum theory of gravity – is the neatest theoretical solution, but it has been elusive. Some candidate theories would seem to entail additional forces that, at very fine timescales, create an imbalance in the pull of gravity for different objects. Indeed, the observation of a tiny and hitherto imperceptible difference in acceleration for two falling objects could be the first evidence that general relativity is flawed, ushering in a new paradigm in modern physics.

Before the turn of this century, the best tests of gravitational free fall could find no deviation in the acceleration of two masses to within one part in 10 trillion. But a new host of lab- and space-based experiments promises up to a 10 000-fold increase in this precision, potentially offering the first chance of testing quantum gravity theories. What is more, some experimentalists are presenting new ways to approach tests of free fall – for example, by employing purely quantum systems, or antimatter. The question “Does everything fall back to Earth at the same speed?” may soon have an answer far more accurate than ever before. […]

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Plugging the neutron deficit

Physics WorldJon Cartwright

As Europe’s neutron supply could fall by as much as half within the next couple of decades, newly developed sources could stave off the decline

There are good reasons to get excited by the European Spallation Source (ESS), which is currently under construction in Lund, Sweden. When the machine finally goes online – and 2028 is the current completion date – it will be the world’s most intense particle accelerator, generating up to 100 times more neutrons than any of today’s sources. Like a giant microscope, it will allow unprecedented studies into various fields – particularly the science of the everyday, such as plastics, pharmaceuticals, biological matter and nanotechnology. The ESS is a fitting tribute to Europe’s neutron research community, which is estimated to be by far the world’s largest, comprising some 6,000 scientists and engineers.

Against this starry-eyed picture, a report published in March by the European Strategy Forum on Research Infrastructures (ESFRI), an EU body, makes for sobering reading. Europe’s neutron community has been fostered over time by a great network of small to large flux neutron sources, two thirds of which were built in the 1960s and 1970s. The majority of these sources are set to close within a decade, and several smaller research reactors have been decommissioned already – those at the Risø National Laboratory in Denmark (in 2000), at Forschungzentrum Jülich (in 2006) and at Gessthacht in Germany (in 2010). Two of the biggest sources – the Orphèe reactor at the Laboratoire Léon Brillouin (LLB) in Saclay, France, and the BER-II reactor at the Helmholtz-Zentrum Berlin in Germany – are expected to close down within four years. By the mid 2030s, according to the ESFRI’s Roadmap, the best-case scenario is a 30% drop in neutron instrument time. The worst-case scenario: a 50% drop.

Simply put, in decades to come the ESS may be a transformative neutron source, but there may not be much of a neutron community left to use it. “The renewal of intermediate neutron sources becomes necessary to maintain a ‘critical mass’ for the neutron user community, otherwise new powerful sources such as the ESS become almost useless,” says Jacques Ollivier, a physicist at the world’s current leading neutron facility, the Institut Laue-Langevin (ILL) in Grenoble, France. The ILL itself is set to close in 2023 unless its partners agree otherwise. […]

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Sharpening up emissions from Asian land-use change

Energy & EnvironmentJon Cartwright

Carbon emissions due to changing land use and land-cover in Asia are becoming increasingly important worldwide, according to an international group of researchers.

Despite a steady decline in carbon emissions since the 1990s in the continent as a whole, South East Asia continues to see high emissions due to deforestation. But emissions due to land-use change are still hard to estimate accurately because of poor land-use definitions in the scientific literature, the team believes.

“A lot of the disagreement in our estimates simply comes from definitions,” said Benjamin Poulter of Montana State University, US. […]

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