Physics – Ceri Brenner

The diffraction, or spreading, of waves through and around obstacles is behind lots of things we all experience: hearing a conversation around a corner, receiving radio signal even in the shadow of hills and seeing a rainbow of colours from the surface of a CD. A wave is strongly diffracted when its wavelength is a similar size to the gap or slits that it’s passing through.

In January 2016, researchers from University of Strathclyde published research in the journal Nature Physics exploring what happens when the most intense laser in the world diffracts through a micro-pinhole. The laser light was infrared, meaning the wavelength was approximately one thousandth of a millimetre (one hundredth the width of human hair).
Fabricating a pinhole of this size and then making sure the laser hits the target is no easy feat. The laser temporarily transforms a micron-size blob of the solid material into the fourth state of matter, plasma. This plasma becomes so hot that it allows the laser to pass through, acting as a pinhole. This pinhole is about the same size as the wavelength of the laser, so “ta da!” – the intense laser diffracts strongly.

They observed the effect of the diffraction by finding relativistically energetic beams of charged particles were being emitted in spiralling patterns. The laser was acting as a miniature particle pusher (aka accelerator) and the diffraction was whizzing the particles up into a spin.

While beautiful on a fundamental physics level, marrying the basic phenomena of diffraction with the extremity of super intense laser light, this work is also highly innovative. These miniature laser accelerators are in development around the world as a next-generation technology to generate particle and x-ray beams for all sorts of applications. The potential uses range from high-precision x-rays and protons for medical imaging and proton cancer therapy through to high-resolution x-rays for nuclear waste barrel and port security inspection.

Ceri Brenner is a physicist who works for the Science and Technology Facilities Council


Biology – Lydia Leon

Despite its bad reputation, pain is important. Just look at individuals totally unable to feel pain: they face a lifetime of unintended injury and risk. Congenital Insensitivity to Pain (CIP) has been well studied. Rare genetic mutations have been identified as a likely underlying cause.

One mutation leads to the loss of an ion channel found throughout the body, NaV17. Ion channels let charged particles flow into and out of nerve cells, enabling electrical signals to travel from a painful stimulus – say a finger in a burning flame – to the processing centres in our brain. We feel pain, and respond by pulling away. It has long been assumed that NaV17 CIP sufferers live without pain because they can’t fire the right signals in response to danger.

Despite significant investment by pharmaceutical companies, attempts to mimic the painkilling (analgesic) effects of NaV17 mutations have proved largely unsuccessful, a fact that lead Professor John Wood’s team at UCL to suggest that other physiological changes may be involved. After an experiment comparing patterns of genetic activity between patients and normal individuals, the team observed huge increases in a naturally occurring opiate painkiller, an enkephalin, in CIP patients. It appeared that a constant exposure to high levels of these enkephalins, rather than an absence of the NaV17 channel itself, was causing CIP in these patients.

The group attempted to treat a NaV17 CIP patient with Naloxone, a drug normally used for heroin and morphine overdoses that blocks the analgesic activity of enkephalins. For the first time in her 30-year life, the patient felt pain. A recent fracture in her leg hurt, and tests showed an 80 per cent increase in sensitivity to pain. Although the change was transient, this discovery opens up fresh avenues of research not just for CIP but for one of the most poorly met challenges in modern medicine: the effective, safe treatment of chronic pain. The team are so confident about the power of this discovery, published last December in Nature Communications, that Wood has already taken out a patent on its use.

Lydia Leon is a PhD student at University College London


Chemistry – Mark Lorch

Farts are a problem, especially from cows. The methane they contain is a major greenhouse gas, second only to carbon dioxide (CO2). The reasons for the increase in atmospheric CO2 are clear; why the concentration of methane has increased 2.5-fold since the the industrial revolution is not. There are a myriad of natural and man-made methane sources and sinks; micro-organisms in sediments, animal digestive systems, petrochemical industry and piles of waste emit the gas. This is balanced against natural degradation of methane in the atmosphere and other microbes digesting the gas.
Techniques for tracking methane do exist. Small areas can be sampled by sucking up gases and analysing them. But using these to identify sources of gas and how they flow around a volume is laborious. Techniques that analyse larger areas don’t reveal individual sources.

To solve this, a group based in Stockholm have come up with a camera that makes methane visible and filmable. The videos, published in Nature Climate Change, reveal methane as if it were purple smoke billowing out of barns, chimneys and piles of sewage. The technique uses infrared hyperspectral imaging. Molecules absorb infrared light in characteristic ways, depending on their structure. So a given chemical will have a specific hue of infrared. If a camera is finely tuned enough to differentiate between these infrared “colours” then it produces images of plumes containing a given chemical.
Put another way, our eyes are capable of spectral imaging: we split the light spectrum up into red, green and blue light. Our brains then reconstruct millions of colours from these three signals. Hyperspectral imaging dissects the light being received into much narrower wavelengths than our eyes are capable of, then reconstructs the signals to reveal the unique “colour” of a molecule.

The result is a camera that allows the flow and concentration of methane to be easily tracked in real time. And these could easily be set up to audit methane emissions from industry – or to track cow farts

Mark Lorch lectures in chemistry at Hull University