Australasian Science: Australia's authority on science since 1938

Exclusive subscriber content

By Stephen Luntz

Subscribe for complete access to dozens of Browse articles and features each month.

A New Type of T-Cell
An unexpected observation has led to the discovery of a new type of immune cell, although so far its role in the immune system remains largely unknown.

The new cell is a form of natural killer T-cell (NKT). Most of the immune system’s T-cells attack proteins on the surface of viruses or bacteria, but NKT cells attack fatty lipid-based molecules.

Prof Dale Godfrey of the University of Melbourne’s Department of Microbiology and Immunology says that the new cells are quite rare, and suspects that those who had seen them before dismissed them as a mistake.

“The identification of a new cell type paves the way for many new studies into the unique function of these cells and how they might be harnessed for the development of new types of vaccines,” he says.

Lipids are not necessarily a better target for the immune system than proteins, but they provide an extra option. “Interestingly though, glycolipid-reactive T-cells tend to be much more reactive than protein T-cells, so they have a powerful impact on the immune system,” Godfrey says.

NKT cells have been implicated in coronary artery disease by attacking lipid-containing plaques, causing inflammation, but are also believed to play a role in the body’s cancer surveillance. It is too early to tell whether the new cell has a role in either of these diseases, but Godfrey says: “We’re excited because it is a new kind of cell, related to cells we know have a powerful role, but we don’t know what its role is yet”.

The discovery was announced in Nature Immunology.

Decorations Protect the Web
Orb-weaving spiders include highly visible crosses, circles or lines in their webs, but the reason for these has been obscure. The decorations reflect UV light, and might attract some insects, but they could also warn potential predators or prey of the presence of the web, which is presumably the last thing the spider would want.

Now it seems that these web decorations are created for the orb-weaving spider’s own protection. “It’s much like we mark glass windows with tape to prevent people walking into them,” says Prof Mark Elgar of the University of Melbourne’s Department of Zoology.

“Most people who have investigated the evolutionary significance of decorations have looked at the fact that different species decorate their webs to different extents, and observed the foraging success as a result,” Elgar says. Instead he decided that “this is variable behaviour” and set about seeing what circumstances would cause the spiders to change their approach.

Elgar damaged the webs of various spiders, some mildly and some severely. “The fact that spiders increased their decorating activity in response to severe damage but didn’t increase their decorating following light damage suggests that the conspicuous building of silk crosses serves to make webs more visible to animals that might accidentally walk or fly into them,” he says.

A damaged web exposes the spider to greater danger from predators, and costs a day of catching prey while the web is re-spun. Consequently, if webs are located where they might be threatened by large animals it makes more sense to decorate the web and keep them out.

The finding does not explain how it is that potential prey is not also warned off by the presence of decorations. However, it follows previous work by Elgar showing that if a web was damaged on one side the spider would be inclined to recreate it with a slight shift across in the opposite direction, presumably because some locations are more dangerous than others.

Elgar says he would not be surprised if the spiders could differentiate between different sorts of damage, and might ignore damage caused by strong winds or other factors that could not be visually deterred.

Sleep Disturbance a Sign of Parkinson’s Disease
Some little-known symptoms can provide early warning of Parkinson’s disease. “Possibly the most dramatic of its symptoms is known as Rapid Eye Movement Sleep Behaviour Disorder,” says Dr Simon Lewis of the University of Sydney’s Brain and Mind Research Institute. “Parkinson patients have been known to start acting out in their dreams, often punching or kicking the person sharing their bed.”

The major drugs used to treat Parkinson’s disease are not necessarily helpful here. “Some people get better, but some find the sleep behaviour actually gets worse,” Lewis says, describing one patient who broke his wife’s nose while asleep. Fortunately some drugs can reduce this symptom and “save a few marriages in the process”.

While the same symptoms can be caused by other conditions, Lewis recommends that people who may be suffering from the condition see a GP and get a referral to a sleep physician. MRIs can reveal the parts of the brain activated during sleep disturbance, providing an indication whether someone is likely to develop Parkinson’s disease in time.

Other symptoms, such as mood change, loss of smell and constipation, can also be related to Parkinson’s. A combination of several of these symptoms may be indicative.

Current Parkinson’s drugs treat the symptoms rather than curing or preventing the disease. However, Lewis is on the advisory board of the producers of Rasagiline, a drug that slowed the early progress of Parkinson’s disease in one study. If the findings are confirmed Lewis says the importance of early diagnosis will increase substantially.

Lewis advises people who are considered likely to suffer Parkinson’s disease within a few years may find certain exercises beneficial.

Fruit Beats Vitamin Supplements
Mice absorb five times as much vitamin C from kiwi fruit as they do from an equivalent amount of purified supplements. The finding calls into question the value of the huge food supplement industry, as well as the validity of some past scientific research.

A/Prof Margreet Vissers of Otago University says her results were quite unexpected. “The kiwi fruit versus supplements was a secondary result to our research,” she says.

Vissers was investigating the theory that recommended vitamin C intakes are set too low. “They’re based on the intake required to stop you getting scurvy,” she says. “However, we have evidence that a lot of organs – such as the liver, kidney and heart – are depleted.”

Most mice make their own vitamin C, so Vissers compared the levels in the organs of a strain that can’t do this with those in wild-type mice. The mice were fed a low vitamin C diet for a period and then given either kiwi fruit or purified vitamin C.

Vissers says kiwi fruit was chosen because it is very high in vitamin C, mice like it, and people eat substantial servings.

As well as absorbing vitamin C better from kiwi fruit, Vissers found that mice retained the fruit-sourced vitamin better than vitamin C absorbed from supplements. She says she has “no idea” what is causing the higher absorption from fruit but suspects that absorption and retention may be bolstered by different factors.

The discovery is not wholly unprecedented. Vissers says that in the 1930s and 1940s some studies found similar results, with speculation of a mystery compound known as “vitamin P” for its capacity to protect vitamin C in food. However, this belief fell into disfavour.

“The findings of the mouse trial have important implications for human nutrition,” Vissers says. A pilot human trial was conducted last year, and Vissers is about to start a more substantial trial on people with poor diets.

The findings may shed light on the question of why studies differ over whether large doses of vitamin C are effective against the common cold (AS, September 2006, p.10). However, Vissers says that variations in definition and study design also have a role.

Vitamin C is already known to assist with iron absorption, bolstering the more general case that whole foods are better sources of nutrition and supplements.

The research was published in the American Journal of Clinical Nutrition, and assisted by the kiwi fruit industry.

Early Visual Decline Test
A test that indicates signs of visual decline before age-related macular degeneration (AMD) takes hold may help people avoid the disease that is affecting the sight of one in seven Australians over the age of 50.

AMD is caused by a combination of genetic and environmental factors, the latter including poor diet, lack of exercise and smoking. Although we can test for a genetic predisposition for the disease, no reliable test exists prior to the small changes at the back of a patient’s eye that ophthalmologists use for assessment.

However, Dr Beatrix Feigl has found that the “dim light vision” test correlates with genetic factors that can predict AMD. The test uses varying light stimuli to distinguish the response of the rods and cones in the eye under low light conditions. People with three different genetic risk factors for AMD had lower visual functioning using this test.

“The test is a research instrument used in basic science,” Feigl says. “We are the first to match it to genetic factors.”

The work was published in Investigative Ophthalmology and Visual Science. Feigl is now beginning a longitudinal study to see if dim light vision results correlate with the development of AMD over time.

At the moment no cure exists for AMD, although some treatments exist for those with the wet form of the disease. However, Feigl hopes that evidence of loss of visual functioning may spur those most at risk to change their lifestyle in ways that reduce the chances of developing the clinical condition.

Scientists Play Possum Matchmakers
The transfer of six male mountain pygmy-possums from Mt Hotham to Mt Buller has been hailed as a success after the capturing of a hybrid juvenile.

The existence of a colony of mountain pygmy-possums on Mt Buller was only discovered in 1996, and since then the population has crashed from around 300 to 30. “In that time they’ve lost 75% of the genetic diversity, so their ability to handle climate change and disease is being lost,” says Dr Andrew Weeks of the University of Melbourne’s Department of Genetics. “They’re also inbreeding.”

Weeks blames the population decline on habitat loss and an increase in predators. However, he says that since the discovery of the possums “Mt Buller has been very active in restoring habitat and controlling pests”. However, without a restoration of genetic diversity this activity would probably be too late.

The Mt Hotham population numbers around 1000, and is in a far better genetic state. Female mountain pygmy-possums are territorial, and Weeks says that Buller females will have occupied the best breeding spots. The males migrate across territory seeking females to mate with.

Although only one juvenile has had its mixed heritage confirmed genetically, Weeks says that a typical litter is three or four individuals, so he is confident that others exist. “They’re very hard to catch at that age.” Whether other successful matings occurred remains unknown.

Caffeine and Stress Create Hallucinations
People who are suffering from stress and consume caffeine equivalent to five cups of coffee per day are more likely to hallucinate, a La Trobe University study has found.

Prof Simon Crowe of the School of Psychological Sciences asked 92 people to report the stressful events that had happened to them in the previous year and describe their caffeine intake. He then asked them to listen to some white noise after telling them they might hear snatches of Bing Crosby’s White Christmas mixed in. They were asked to press a button when they thought they heard the song.

The song was never played, but on average the participants pressed the button a little more than once per trail. Those whose self-description placed them in the high caffeine– high stress group thought they had heard the song an average of three times. Those with low stress levels, but high caffeine consumption, were also more likely to think they heard the song, but not by a statistically significant amount.

In the journal Personality and Individual Differences, the authors acknowledge: “There are, however, a number of limitations that can be identified with the study”. For example, the sample size for high caffeine users was too small to establish whether the source or timing of the caffeine consumption was important. Moreover, while some factors that contribute to high caffeine consumption were ruled out as influencing factors, they did not control for age, body mass or cigarette smoking.

“Caution needs to be exercised with the use of this overtly ‘safe’ drug,” Crowe says. Some other studies have indicated a correlation between caffeine use and schizophrenia, but this research demonstrated that hallucinations may be more likely even among people who are far from clinically ill.

“The results also support the continuum theory of schizophrenia in that stress plays a role in the symptoms of schizophrenia and that everyone, to some degree, can experience these symptoms. This was demonstrated by a significant effect of stress on the occurrence of hallucinatory experiences, or hearing the song,” says Crowe.

The story gained considerable media coverage, leading some worried people to contact Crowe. His advice is: “If you’re highly stressed it’s better not to increase that by adding a lot of a stimulant like caffeine. It’s a drug, and moderation is appropriate.”

Extract Suppresses Tumours
Polysaccharopeptide (PSP), a compound extracted from the turkey tail mushroom, has had complete success in suppressing prostate tumours in mice.

“In the past, other inhibitors tested in research trials have been shown to be up to 70% effective, but we’re seeing 100% of this tumour prevented from developing with PSP,” says Dr Patrick Ling of the Queensland Institute of Technology. “Importantly, we did not see any side-effects from the treatment.”

Turkey tail mushroom has been considered beneficial in traditional Chinese medicine, but Ling says one would need to eat unrealistically large amounts to get the prostate cancer-preventing effects he observed in mice.

PSP has been found to be effective against other forms of cancer before, but Ling says: “What is exciting about our research is that it kills cancer stem cells”.

Ling has received no grants to continue research on PSP, but a fundraising event has been organised by people excited by the potential of the work.

Although Ling says the turkey tail mushroom makes good soup, with evidence it bolsters the immune system, he has heard that its importation into Australia may be restricted so he doubts it will be on the event’s menu.

Punishment Fits the Crime
The first recorded example has been found of a non-human species adjusting the punishment it meets out to another of its species according to the severity of the misbehaviour. It comes not from apes but cleaner fish.

Dr Lexa Grutter of the University of Queensland’s School of Biological Sciences has demonstrated that cleaner fish prefer the mucus of the fish they clean to parasites, and are sometimes tempted to cheat by eating the mucus instead (AS, August 2006, p.9). Cheated client fish refuse to be cleaned by a cheater, and sometimes react aggressively. Fish that witness a cleaner cheat usually go elsewhere.

In collaboration with UK and Swiss scientists, Grutter has revealed that male cleaner wrasse punish cheating females, particularly if the cheating is of a valuable client.

Male cleaner wrasse usually have a harem of around three females. The male and largest female clean together, with the other females spread out at other stations. Males occasionally visit the other females to mate and maintain their territory.

Males have been observed chasing females that cheated, presumably because if the client leaves the male loses the chance to feed as well. Grutter and her colleagues modelled this situation by presenting cleaner wrasse in lab with plates made of prawns, which they prefer, and fish flakes. When either fish ate the prawns the plate was removed. “They learn very fast,” Grutter says. “In a couple of days they knew not to eat prawn.”

When the female ate prawn the male would punish her by chasing and biting. After punishment the females were more likely to behave. In Proceedings of the Royal Society B Grutter revealed that the males adjusted their punishment, with it being more severe when the plate was larger, representing a high-value client.

Males were also more aggressive in punishing females close to their size. Larger female wrasse can turn into males, and Grutter theorises that the males were keen to prevent the female growing enough to change sex, reducing the harem size and potentially creating rivals.

“This is the first non-human example of where punishment fits the crime and results in the offender adjusting their behaviour according to the potential penalties,” Grutter says.

Grutter tactfully avoids mentioning another finding. Male cleaner fish are more likely to cheat than females, having only one potential source of punishment.

Grutter has also recently published research in Current Biology showing that cleaner fish are less likely to cheat if they have an audience of fish they are seeking to impress.

Testosterone Spray Restores Women’s Memory
Research indicating that testosterone can restore memory in women aged 45–60 has been bolstered by the addition of a control group. Dr Sonia Davison and Prof Susan Davis of Monash University’s Women’s Health program observed a remarkable recovery in the memories of nine women given testosterone sprays (AS, Jan/Feb 2010, p.6). However, their study was criticised for lacking a control group.

Davison and Davis have now conducted similar tests on 30 women of the same age who received no treatment, and found that their performance did not improve over a similar period. In each case the women were given tests such as being read a shopping list and asked to recall the items on it immediately and 20 minutes later.

“There was no placebo, so it’s still not perfect,” Davison admits. “However, this was a pilot study. You normally don’t get results with such a small group.” Only nine women were originally given the spray because the study involved extremely expensive fMRI scans.

A larger study is now being conducted using cognitive tests but skipping the scans.

“What is exciting is that the testosterone-treated women were all healthy, with no cognitive impairment, and there was still a definite treatment effect from the spray,” says Davison.

Women aged 55–70 who are interested in taking part can call 03 9903 0827.

Good News for Venice
Venice is less threatened by climate change than previously thought, according to Dr Alberto Troccoli of CSIRO. The low-lying city may survive the rising waters, just as it has defeated so many previous threats.

Venice has been inundated many times over the centuries, and this became worse during the 20th century as the drawing of water from artesian wells caused the city to subside. Now that the wells have been banned, the threat comes from global sea level rise.

However, most of the city is still at least a metre above the Adriatic Sea. Not only is there much disagreement about the future rate of sea level rise, but the rise will not be evenly distributed across the world’s oceans. It may take many decades for the water from melting polar glaciers to raise the Adriatic.

The more immediate threat comes from frequent storm surges, where low pressure systems crossing the region lift the water level. Moreover, the same atmospheric conditions cause Sirocco winds to drive waters from the south-eastern Adriatic into the Venetian lagoon.

However, Troccoli found climatic models predict that these low pressure systems will be pushed further north, leaving the Mediterranean region relatively unscathed. “This pattern has been observed by others as well,” he says. An anticipated 30% decline in the frequency of such events is enough to offset a 17 cm rise in the Adriatic, which Troccoli extrapolated from the trend in recent decades.

Troccoli acknowledges that the extrapolation is conservative, as glacial melt is likely to accelerate, but says that no reliable predictions for sea level rise in the area exist. He also anticipates that the storms will decline in intensity.

The findings are consistent with recent observations that major storm surges have become less frequent. “The survival of Venice and its lagoon is seriously questioned under the International Panel on Climate Change global sea level rise scenarios,” Troccoli says. “The results of this study, published in the journal Climatic Change, emphasise the need for location-by-location studies to determine coastal flooding impacts.”

While the findings are good news for Venice, some other locations may find themselves exposed to larger and more frequent storms as a result of altered weather tracks. Troccoli has been applying similar methods to projections for Australia’s east coast.

Being Cold’s a Drag
Hot bodies can have up to 85% less drag than bodies of similar shape at lower temperatures, according to a study published in Physical Review Letters. What started out as a discussion over a few beers may prove useful for doubling the speed of objects moving through water.

Prof Derek Chan of Swinburne University’s Faculty of Life and Social Sciences was at a pub with long-time collaborator Dr Ivan Vakarelskit discussing the way drops of water appear to dance on very hot plates as a result of the Leidenfrost effect. The same effect can be observed at room temperature with liquid nitrogen. “What struck us is that the drops last a long time before they vaporise,” Chan says. “We wondered what would happen if you turned the effect inside out and put a hot solid into a liquid.”

They found that if they can heat a ball enough it will travel through a liquid much faster than a cold one. “A body hot enough to vaporise the thin layer of liquid in contact with it can drastically reduce energy-sapping drag forces when such bodies travel at high speed through the liquid,” Chan says.

Whether the discovery can have practical applications remains to be seen. Chan notes that it is not simply a matter of warming an object slightly and having it go faster as result. Instead, an object needs to be substantially warmer than the boiling point of the liquid through which it is travelling to gain a benefit.

Chan conducted his studies in low boiling point liquids, but taking a submarine’s shell well past 100°C is likely to be far too energy-intensive to justify the reduced drag. There may also be increased corrosion in marine environments. However, torpedoes might be heated to give them extra speed for a short duration.

There is plenty more research to be done. “For one thing we were using spheres here,” Chan says. “Drag has two parts, from the shape and from the skin. We used a sphere because of the simple shape.” Further study is needed to see how more aerodynamically shaped objects are affected.

Groupers To The Rescue
The release of Indo-Pacific native lionfish spells trouble for the Caribbean, but groupers appear to be the one fish species capable of limiting the damage. The discovery, published in PLoS One by Prof Peter Mumby of the University of Queensland’s School of Biological Sciences, emphasises the importance of protecting groupers from overfishing.

“Although lionfish are amongst the most beautiful fish in the sea, they are voracious predators of small fish and conservationists are concerned about their impact on native fish populations,” Mumby says. Lionfish are popular in aquariums, and it is believed the release of a few individuals led to their arrival at all 12 of Mumby’s study sites in 2010, after being unsighted in 2006.

Lionfish have venomous spines that protect them against most predators, but some have been found in the stomachs of groupers, and Mumby observed that lionfish populations were much lower at sites where groupers are common. He suggested: “We’ll have to develop a taste for lionfish instead of grouper and drastically reduce the fishing of this species”.

Seagrass Under Threat
The seagrass Posionia sinuosa, which is found exclusively in Western Australia and South Australia, has been classified as one of ten endangered seagrasses in the world. The International Union for the Conservation of Nature classified P. sinuosa as vulnerable while determining the status of 72 seagrass species.

Sea grasses are one of the few ecosystems that appear to be benefiting from global warming, according to Prof Gary Kendrick of the University of Western Australia’s Oceans Institute. However, Kendrick says that “Posidonia sinuosa is declining at an alarming rate – about 1.2% every year,” as a result of coastal development, degraded water quality and dredging.

Seagrasses are important habitats and nurseries for commercial fish species and crustaceans, and are also a major carbon dioxide sink.

SKA Moves Forward
Radio telescopes across Australia and New Zealand have been linked by optical fibre in a step towards the establishment of the world’s largest telescope, the Square Kilometre Array (SKA).

The Australian SKA Pathfinder telescope in Western Australia and telescopes in NSW, Tasmania and New Zealand combined to study PKS 0637-752, a quasar 7.5 billion light years away. PKS 0637-752 is thought to be the result of two black holes orbiting each other.

“It’s a fascinating object, and we were able to zoom right into its core, seeing details just a few millionths of a degree in scale, equivalent to looking at a 10¢ piece from a distance of 1000 km,” said Dr Tasso Tzioumis of CSIRO.

The telescopes were all controlled from Sydney, while the data were streamed to Perth for processing into a single image at Curtin University, a step towards processing the daunting amount of information the SKA will produce.

Bio-Jet Fuel Could Work
Aviation is often considered the most difficult source of greenhouse gas emissions to switch to a non-polluting path, but a CSIRO study named “Flight Path to Sustainable Aviation” found that non-food biomass such as crop stubble or algae could produce substantial amounts of jet fuel.

The report finds: “The only alternative fuel which can meet all of the environmental, economic and technical challenges is sustainable aviation fuel derived from biomass”. However, it acknowledges: “There are currently no significant supplies of sustainable aviation fuel anywhere in the world”.

While a variety of new and existing non-food biomass resources are expected to be able to supply 46% of Australia and New Zealand’s aviation fuel needs by 2020, competition for some of the feedstocks will come from other forms of transport and industries such as cosmetics.

Colds Are Hormonal
Women produce a stronger immune response to rhinoviruses, the main cause of the common cold, according to a paper in Respiratory Research. “The difference disappears at 50,” said Prof John Upham of the University of Queensland’s Lung and Allergy Research Centre, “so it’s a hormonal response, not genetic”.

Some research suggests that our reaction to colds is actually an inappropriate immune response. Upham acknowledges that a strong response to rhinoviruses is not always good. “There’s probably a Goldilocks effect here, but generally women will recover more quickly than men.

Studies of other virus infections suggest that oestrogen is the mostly likely candidate. Upham hopes confirmation may lead to clues for a vaccine. More than 100 serotypes of rhinoviruses are known, so any vaccine will need to target sequences conserved across many strains.

Left-Hander’s Are Not Gifted
Being left-handed correlates with lower cognitive ability that is equivalent to being born prematurely, a Flinders University study has claimed.

Prof Mike Nicholls of the Brain and Cognition Laboratory contradicted the theory of left-handed giftedness. “The evidence, based on our analyses of very large databases of handedness and other attributes in people across Australia, the UK and the USA, doesn’t bear out that myth,” Nicholls says. “Our study of members of the same family confirms that left-handed children will do worse than their right-handed siblings.”

The Brain and Cognition Laboratory is also studying spatial attention. “We’re very interested in how the general population tends to pay more attention to the left-hand side of an object than the right,” Nicholls says. “When AFL footballers aim for the midpoint between two posts, they tend to kick slightly to the right of middle.”

One Kangaroo’s Poison
Cyanide is crucial to the germination of kangaroo paw seeds after a bushfire, a paper in Nature Communications has revealed.

“We found when plants burn they produce a substance that, after rain, hydrolyses to release cyanide,” says Dr Gavin Flematti of the University of Western Australia’s School of Biomedical, Biomolecular and Chemical Sciences.

Many plants use cyanide against herbivores, and it seems kangaroo paws, among others, have adapted it to form a trigger, alerting buried seeds of the best time to germinate.

Flematti was part of previous research revealing that compounds in smoke known as karrikins play a similar role. “We now find that many plant species respond to both karrikins and cyanide, while some respond to only one, such as the kangaroo paw,” Flematti says.

Rain Speeds Arctic Melt
A vicious circle has been created in the Arctic, with rain replacing snow and driving more rapid melting.

Dr James Screen of the University of Melbourne’s School of Earth Sciences reported in Climate Dynamics that warmer temperatures have increased the number of days on which precipitation falls as rain rather than snow. “As a result of this temperature shift, we estimate that there has been a 40% decrease in summer snowfall over the last 20 years,” said Screen.

“Snow is highly reflective and bounces up to 85% of the incoming sunlight back into space. Snow on top of ice effectively acts as a sunscreen protecting the ice from the power of the sun’s rays.”

Screen says that this affects sea ice. “As the snow cover has decreased, more sea ice has become exposed to the sunlight, increasing the melting of the ice.”

Kidney Risk from Premature Birth
Long-term kidney problems can be added to the risks associated with premature birth, with A/Prof Jane Black of Monash University’s Department of Anatomy and Developmental Biology finding abnormalities in the kidneys’ nephrons. “An average person has around 900,000 nephrons and the number we have at birth is the number we have for life,” Black explains.

“The majority of nephrons are formed in the last trimester of pregnancy at a time when preterm infants are already delivered. We have shown that babies born preterm do continue to grow nephrons after birth. However, in some babies up to 13% of the nephrons are abnormal and unlikely to ever be functional. So these babies will start life with a reduced number of functional nephrons.”

Low nephron numbers have been associated with hypertension and kidney disease in adults. Black notes that high survival rates for preterm babies are a relatively recent phenomenon, so the adult impact is not well studied.

Asteroid Sails Close
The University of Western Australia’s 1-metre Zadko Telescope tracked near-Earth asteroid 2011MD as it shot across Australian skies in June at a height of just 12,000 km. 2011MD was at most 12 metres long, but Prof Michael Boer, visiting at UWA, said: “If it were to enter the Earth’s atmosphere there would be a big bang and it would probably explode. A so-called air blast exploded over Russia in 1908 and the resulting air blast flattened a forest.”

Objects of this size come within the orbit of geosynchronous satellites approximately once every 6 years. 2011MD was first detected by a US asteroid tracker on 22 June and made its closest approach on the 27th.

Diamonds Aren’t Forever
Diamonds can be degraded by sunlight, according to work published in Optical Materials Express by A/Prof Richard Mildren of Macquarie University’s Photonics Research Centre. However, under normal sunlight conditions it would require the age of the universe to have a noticeable effect on our precious gems.

Mildren found that intense ultraviolet C light can rapidly eat into the surface of diamonds, causing small pits to appear and reducing the mass. The vast majority of UV C light is blocked by the ozone layer.

“If we can make structures in the diamonds that enable us to control the position of the light within a very narrow filament in the diamond, that’s the first step to making smaller and more efficient optical devices such as those used in quantum computing and high performance lasers,” Mildren says.