Tuesday 10th December 2013
Science in Brief Conor O’Donovan
Sex survey - a decade of changing habits and opinions The results of the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) in the UK, published recently in the Lancet, provide for stimulating reading. In the past 10 years, the rates of two high-risk sexually transmitted subtypes of human papillomavirus (HPV) fell from 11.3% to 5.8%, and attendance at STI clinics increased from 9.2% to16.9% in men and from 8.7 to 27.8% in women. Women reported increased numbers of male partners over the lifetime, and increased sexual experiences with female partners. There was expansion of oral and anal sex in the heterosexual population. Acceptance of
same-sex partnerships, and intolerance of non-exclusivity in marriage also both increased. Low sexual satisfaction and function were associated with the end of a relationship, inability to talk easily about sex with the partner, and not being happy in the relationship. The rate of “completed nonvolitional sex” was 9.8% in women (median age 18), and 1.4% in men (median age 16). In most cases, the perpetrator was known to the individual. Younger participants surveyed were also more likely to have told someone about it, and to have reported it to the police.
HIV vaccine no closer Illustration: Maria Kavanagh
Symmetrical snowflakes and chaotic crystals: The science behind the sneachta With the festive season on the way, Dylan Lynch explores the science behind a white – or perhaps yellow – Christmas..
I Dylan Lynch Staff Writer
t’s that time of year again. Grafton Street is all lit up, the woolly hats and ugly jumpers come out, and there’s a 25 minute delay getting home on the Dart: it’s Christmas. And since there’s a good chance of getting a white December this year, let’s look at some of the weird and wonderful properties of snowflakes that you might not have heard before. First and foremost, almost all snowflakes are unique. According to physicist Kenneth Libbrecht from the California Institute of Technology, finding two identical snowflakes is like “shuffling a deck of cards and getting the exact same shuffle back. You could shuffle every second for the entire life of the universe, and you wouldn’t come close to getting two of the same.” So while two snowflakes can look strikingly similar, they will never be exactly the same. Snowflakes form in the clouds from water that has been evaporated from rivers, transpired by plants and breathed out by you. The crystals form in different weather conditions, and from different water sources all over the world. However, the uniqueness of snow is barely scraping the surface of one of nature’s most beautiful marvels. Let’s talk about the shape. Most snowflakes have
six-fold symmetry, which means that the snow-crystal can be divided into six equal parts. Try and imagine cutting a snowflake using a straight line and folding it over on to itself, and you’ll get the idea. This hexagonal shape is due to the bonding of the two elements that make up water. A water molecule is composed of two hydrogen atoms and a single oxygen atom, and so when the water cools and freezes, the crystals grow in very specific ways from a central point or ‘nucleus’. Most snowflakes won’t look exactly like the drawing on your Christmas card, but they all seem to have six protruding ‘limbs’, and a hexagon at their core. The shape of snowflakes is also closely related to the weather conditions present in the 15 to 45 minutes it takes for one to form. Crystals being formed in high humidity and -15 °C weather will be beautiful ‘dendrite shapes’ (dendrite comes from the Greek word Dendron, meaning “tree”), while those growing in warmer temperatures and lower humidity may be in the shape of a plate or prism. From a mathematical point of view, snowflakes have been incredibly interesting in terms of studying infinity concepts, and also ‘chaos theory’. One of the most famous snowflakes in existence is known as the Koch
Snowflake, which takes its name from the Swedish mathematician Helge von Koch who studied the shape in terms of chaos theory and fractals. The shape regresses on itself infinitely, meaning that the closer we look into the snowflake, we just see the original shape but smaller. Think of placing two mirrors in front of each other and standing between them: the image of your face will become infinitely smaller between the mirrors, but no matter how closely you look you will still see your own head in the glass. This represents the idea of how snowcrystals can behave and form in a theoretical way, but your average snowflake may not be infinite itself. Is snow always the pure white fluff that covers the family car and causes the marquee out back to collapse? There is no doubt that numerous people have told you “don’t eat yellow snow!”, but oddly enough, they’ve been right all along. There have been a few rare cases of discoloured sleet and snow falling from the skies. In February 2002, yellow and orange snow fell in western Siberia. The official report concluded that the snow was in no way dangerous to humans, however the yellow crystals contained levels of nitrogen and iron four times greater than normal. A similar
case was reported in March 2006, but this time in Seoul, South Korea. More worryingly these flurries contained heavy minerals, meaning they could pose a serious health risk. In both cases, the rare occurrence of yellow snow was attributed to sandstorms in neighbouring countries and territories. One South Korean meteorological officer was quoted as saying “It’s tough to say whether it’s yellow sand mixed in snow or snow mixed in yellow sand. I have never seen yellow snow falling before.” More recently, there have been reports of brown “dirty” snow in Colorado, USA, due to high winds and dust particles being transferred into the air. So this winter when you’re having an annual family snowball fight, remember that you are taking a mathematically-influenced crystalline structure that was grown ever-so specifically and matured for almost an hour and cramming it down the back of your younger brothers jacket, or hurling it at your uncle’s face.
A trial of a potential HIV vaccine, involving 2,504 participants at high risk of contracting the virus has been halted early. Reported in the New England Journal of Medicine (NEJM) the trial’s data and safety monitoring board, found no effectiveness at preventing infection. Vaccine- and placeborecipients had no significant difference in HIV-1 acquisition rate, or viral load set point (level of HIV-1 in the blood at 10-20 weeks
following diagnosis). Though the trial failed to demonstrate efficacy for this vaccine strategy, it is encouraging that negative results have been published in the NEJM. This may be indicative of the growing appreciation of the importance of publishing negative data to direct future clinical trials and prevent unnecessary trial duplication and the inherent harm to patients involved.
CARS microscopy: you can look but you cannot touch!
M Gemma-Lee -Ann Melton Contributor
Gemma-Lee-Ann Melton explores how CARS microscopy has the potential to revolutionise microbiology. icroscopy has helped shaped the modern world. Imaging at the microscopic level changed how illness is treated, prevented and cured. The concept of a surgeon washing their hands to rid themselves of microscopic dangers is a relatively recent addition to their arsenal of weapons to keep you healthy. Germ theory was confirmed by scientists using microscopes to peer into the unseen realm of pathogens, and these discoveries showed us that there is a microscopic world waiting to be discovered. Today, scientists are much more familiar with this world. The collective call from scientists now is for more sophisticated imaging techniques to facilitate more accurate data analysis. The development of improved imaging has been at the forefront of the biological and physical sciences since the first working microscope. There is a lot of debate surrounding the invention of the microscope, a kind of ‘whodunnit’ story with the leading person depending on your historical preference. It is generally accepted though, that the first person to bring the microscope from the realm of curiosity into a useful tool for analysis was Antonie Van Leeuwenhoek who lived in the 17th and early 18th centuries. Van Leeuwenhoek, a Dutch draper and scientist, crafted intricate microscopes that enabled scientists to peer into the unseen, and the science of microbiology was born. Modern microscopy comes in many flavours, from the electron microscope (which, rather curiously to the uninitiated, fires beams of electrons at things to make them visible!) to conventional lenses. Scientists today have achieved the imaging of the
smallest of matter – single atoms – and the hunt for better resolution and more accurate imaging is progressing rapidly. Conventional microscopy routinely involves the staining of a sample for imaging. Biologists call this the “labelling” of a sample. Generally, very few samples can be imaged effectively without labelling. Unfortunately staining can result in the contamination of a sample, and this can render an experiment unfit for long-term analysis. Staining can introduce artefacts to a sample which can influence conclusions of analysis. It is also a time consuming process, and costs laboratories money. Staining usually means a dead sample too, it is pretty hard to keep a small animal or microbe alive while introducing a foreign compound to colour it. Coherent anti-Stokes Raman scattering spectroscopy, or CARS microscopy, is different. CARS microscopy images samples not by labelling, but by taking advantage of molecules intrinsic vibrational contrast, which allows for completely stain-free imaging. CARS achieves this by using three separate femtosecond laser beams that are sent down a microscope to excite and relax defined parts of the molecule to be imaged. This process forces the molecule to release a light particle, or photon, and an image can be translated. CARS microscopy is virtually non-intrusive, and this allows for live – in vivo – samples to be imaged unharmed and in real-time video quality at a spatial resolution of about 300 nanometres. A research group in Ottawa, Canada has been at the forefront of research into CARS microscopy since 2009 when the National
“This technique is allowing scientists to peer into cells, viruses and other living systems with as little disturbance as possible.”
Research Council Canada (NRC) and Olympus America Inc. officially opened CARSLab. “Our microscopes here can do fluorescence imaging, second harmonic imaging and CARS. With the flip of a switch, or the flip of a filter, we can image everything in one go” says Dr. Aaron Slepkov, a research associate with NRCOlympus. “We can really build a story of what is going on inside the cell”. Images of individual cells that make up the ear of a mouse have been achieved by CARSLab using the CARS microscopy technique. This essentially means using multiple CARS simultaneously to ‘illuminate’ the molecule of
interest. ‘It blows my mind!’ says Slepkov. The CARSLab group has primarily focused on the imaging of biological systems, casting light on the intricate world of the very small with as little human interference as possible. This technique is allowing scientists to peer into cells, viruses and other living systems with as little disturbance as possible, and is paving the way for a more accurate database of knowledge concerning biological systems. The implications for disciplines such as medicine and virology are profound. The aim of a researcher is to observe and collect data while interacting with the subject of analysis as little as possible, as interaction inevitably influences the outcome of experimentation – often in ways that cannot be accounted for. The CARS technique has obvious implications for the physical sciences too. The development of microscopes and their properties generally but not exclusively, lie at the feet of physicists. College’s own Photonics Research Laboratory at CRANN, part of the School of Physics, uses and researches this technique. CARS microscopy offers the possibility of increased imaging with the potential for interaction with the sample being dramatically reduced, and many research facilities are beginning to employ this technology as part of their daily research. This technique is advancing research into the properties of light and imaging and is allowing a closer, more accurate look into biological systems. This valuable technology is a new look into the familiar world of biological structures that could have profound consequences for future research and technologies.
The power of subconscious love In the journal Science, strong evidence is presented for the power of implicit, automatic (non-expressed) attitudes towards one’s partner for prediction of change in marital satisfaction over time. 135 newlywed couples answered questions that measured their explicit, conscious attitudes toward their relationship, and underwent an assessment of implicit attitudes (association of positive or negative words with brief images of their partner or control individuals). Couples were followed up for four years. Expressed and implicit attitudes did not correlate with each other, suggesting inability or unwillingness to accu-
Illustration: Maria Kavanagh
rately self-report one’s attitudes toward the partner or relationship. Automatic measures predicted changes in marital satisfaction over time, i.e. those with net positive implicit attitudes from the start experienced less decline in marital satisfaction in the long run. This association was significant despite controlling for several other variables. These findings lend support to the theory of automatic cognitive processes, and also to their role in practical social interactions. We may be able to predict, but not expressly articulate, the outcome of our long-term relationships.