Assessing uncertainties in image registration

Researchers in the US and Denmark have demonstrated a new way to evaluate the uncertainty of deformable image registration (DIR), which tracks the changes of tumours in medical images. According to the study, which was based on real images of patients with prostate cancer, a “distance discordance metric” (DDM) is better able to evaluate uncertainties in DIR than existing methods. The new method should allow radiotherapists to provide cancer patients with more accurate treatment plans (Phys. Med. Biol. 61 6172).

The aim of radiotherapy is to localize radiation to a tumour while sparing healthy tissue, so that a patient does not have to suffer more radiation than necessary. To do this, radiotherapists make use of medical imaging, such as CT and MRI, to identify a tumour’s boundaries. But this is difficult if the relevant part of the body undergoes motion, or if the patient loses weight or the tumour itself begins to change in size. […]

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Photoacoustic imaging quantifies elasticity

Biomedical engineers in the US have developed a form of photoacoustic imaging that can quantify the elasticity of human tissue. The technique, which the engineers tested on skeletal muscle in a human, could be used to monitor the elasticity of the cervix during pregnancy, for example, potentially allowing doctors to predict premature delivery dates (J. Biomed. Opt. 21 066011).

Scientists have known for a long time that a change in the mechanical properties of tissue can be a sign of underlying bodily changes, including those brought about by disease. Physicians can examine tissue for such changes by manipulating them directly, but imaging techniques such as ultrasound, nuclear magnetic resonance and optical coherence tomography can provide more detailed knowledge by mapping the tissue’s internal deformation – that is, strain – under load. If the distribution of stress in the tissue is also known, these techniques can generate images of elasticity, known as elastograms. […]

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Was South Atlantic one of first regions to experience manmade climate change?

The South Atlantic may have been one of the first regions to experience a dramatic shift in atmospheric circulation due to anthropogenic climate change, according to an international study.

The research – which combined computer modelling with proxy records dating back 6000 years – suggests that a low-pressure system to the west of the Antarctic Peninsula has had a rising influence over circulation patterns in the South Atlantic since the 1940s, driving southerly air masses over the Falkland Islands and South Georgia.

The circulation pattern had not previously existed for millennia, the scientists believe, implying its emergence was an anthropogenic phenomenon – although they insist more evidence is needed before making any definite claims. […]

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Can late-imperialist China give climate lessons?

Published in ERW, 10 Aug 2016

Lessons could be learnt from the way that the Chinese economy responded to climate changes in the 17th to 19th centuries, according to a statistical study by researchers in China and Switzerland.

The team found that when China was ruled by its final imperial dynasty, a general cooling of the climate induced long-term fluctuations in the economy. It also discovered that the population acted primarily as consumers rather than producers, leaving it all the more vulnerable to these economic fluctuations.

“To improve current plans of adaptation or mitigation, we need to know about these past interactions between climate change and human societies,” said Qing Pei of the Education University of Hong Kong. “Economy is usually the pillar of a society. Therefore, lessons on climate change and the economy could be [beneficial in understanding] the future of human beings when facing unprecedented global warming.” […]

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Nitrogen fertilizer risks cellulosic biofuel advantage

Published in ERW, 9 Aug 2016

The application of surplus nitrogen fertilizer to cellulosic biofuels can reduce the climate benefit of the crop nearly two-fold, according to a study by US scientists.

The study, which focused on the biofuel crop switchgrass, has shown that increasing application of nitrogen fertilizer leads to an exponential rise in nitrogen leaching and in the emission of the greenhouse gas nitrous oxide. Beyond a small level of fertilizer application, however, the benefit to the crop itself was minimal.

“We are not saying ‘Do not fertilize’,” said Philip Robertson of Michigan State University, US. “If the crop is responsive to nitrogen fertilizer, then it makes good sense to fertilize at rates that result in greater crop growth – but no more than that.” […]

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Gold could have come from colliding stars

Published in Horizon, 4 Aug 2016

If you are wearing a gold ring on your finger, it may well have started life in the collision of two neutron stars – small celestial objects that are formed when massive stars collapse.

That is the conclusion of physicist Dr Andreas Bauswein at the Aristotle University of Thessaloniki in Greece and colleagues, who have been studying the ramifications of such colossal events in computer simulations.

‘The formation of heavy elements is a major topic in stellar astrophysics,’ said Dr Bauswein. ‘We want to understand where and how elements like gold and uranium were produced.’ […]

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Boron carbide bests graphite for proton therapy

Published in MPW, 3 Aug 2016

Scientists in Switzerland have found that boron carbide transmits nearly one-third more protons in the right direction than graphite when used as a degrader for proton therapy. The result suggests that boron carbide could reduce treatment times, with particular benefits for those undergoing eye treatments (Phys. Med. Biol. 61 N337).

Proton therapy is similar to conventional radiotherapy in that it is used to destroy tumours, but in principle has a finite range that spares surrounding healthy tissue. A cyclotron can be used to generate the protons, but these protons will always have the same initial energy and, if left unchecked, can pass through the body having little effect at all. For that reason the beamline’s operators must insert a degrader in the path of the protons; in general, the thicker the degrader, the less the protons’ penetration depth in the body. […]

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Inland water carbon dioxide emissions ‘underestimated’

Published in ERW, 2 August 2016

Estimates of CO2 emissions from inland waters could be underestimated, according to scientists who continuously studied the emissions from a US reservoir.

2 than previously thought, suggests that scientists had previously overlooked rises in emissions at night and from extratropical cyclones.

“The current CO2 emission rates from the global inland waters in the literature may be largely underestimated,” said Heping Liu of Washington State University, US. “Multiple year measurements are really needed to look at how much inter-annual variability in the climate or weather changes the emission rates.” […]

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Is savanna in east Australia controlling world carbon uptake?

Published in ERW, 19 Jul 2016

Much of the variability of the global carbon cycle can be attributed to the changing carbon uptake of savanna vegetation in east Australia, according to scientists in Australia and Sweden.

The researchers believe that the country’s disproportionate effect on carbon-cycle variability is due to the amount of moisture available to the semi-arid region – a factor that depends on the El Niño/Southern Oscillation (ENSO).

However, the scientists also found that the extreme carbon uptake seen in Australia in 2011, which contributed significantly to a particularly high global uptake, was less localized to the east. […]

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Wave erosion compounds damage of rising seas

Published in ERW, 18 Jul 2016

The damage of rising sea levels in the Solomon Islands over the past half century has been exacerbated by exposure to strong waves. That’s according to researchers in Australia who performed the first analysis of changing coastlines on reef islands within the Solomon Islands.

“The islands that were studied did not just ‘drown’ as might be anticipated from sea-level rise, but markedly changed their shape, and in many cases their location, indicating the significance of processes such as wave exposure,” said Colin Woodroffe of the University of Wollongong.

The fate of small, remote islands is of particular concern to those studying the effects of climate change, as rising seas can shrink the land that inhabitants have to live on. As the islands get more crowded, coastlines can be eroded further. […]

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