SCIENCE STUFF

BACTERIA SPIKED BY BLACK SILICON

Dragonfly 03A number of diseases are caused by bacteria. They range in severity from mild, irritating infections or a bit of diarrhoea, to life-threatening illnesses such as bacterial meningitis. Killing harmful bacteria is important in both preventing and treating disease.

There are ways to stop bacteria before they even enter the body. Bacteria are mostly water, so boiling temperatures can cause enough damage to kill most types of bacterial cells. Boiling contaminated water is one way to make it safe for drinking. Some pieces of medical equipment are also treated with high-pressure steam to eliminate any nasties present. However, some bacteria can survive high temperatures.

Another way to kill bacteria is by chemical means. Examples include antibacterial hand soap, and cleaners such as bleach. Sometimes antibiotics – chemicals to treat bacterial disease or infection – are prescribed. However, an increasing problem is antibiotic resistance, where bacteria evolve that cannot be controlled or killed by conventional antibiotics.

Recent research indicates that some surfaces also have bacteria slaying abilities. Inspired by the surface of some insect wings with antibacterial properties, scientists studied a material called black silicon. While it feels smooth to human touch, the surface of black silicon consists of tiny spikes at the nanoscale. The antibacterial insect wings have a similar structure.

Black silicon’s spikes are able to kill bacteria, not through heat or a chemical process, but by impaling them. One advantage of black silicon is that it killed a range of bacteria in the study, while many antibiotics are only effective against particular types of bacteria. The discovery of black silicon’s properties could lead to new antibacterial surfaces, suitable for medical devices.

 

YOUR MICROBIOME

Your microbiome consists of a range of microbes that live in your body. Most of the microbes are bacteria, although it also includes other organisms, including fungi and bacteria-like organisms called archaea. There are a lot of these microbes inside you too: while the human body contains around 10 trillion human cells, the number of microbial cells is estimated to be about 10 times greater!

Most of the human microbiome is found in the intestines, although you can find microbes living in other places, such as in your mouth and on your skin. The fact that most of the microbes are found in the gut means you may also hear them referred to as gut flora. When you were born, you didn’t have a microbiome. Your gut would have been colonised by microbes pretty much as soon you entered the world. These microbes would have come from the environment and people around you.

It turns out that these microscopic buddies are pretty useful to their human hosts. They have been shown to help in the digestion of food, providing energy that would otherwise be unavailable. They also help produce some vitamins, and are also able to help keep harmful bacteria from growing out of control and making you sick.

Scientists are still learning a lot about the human microbiome and what it does. For one thing, most of the microbes are very hard to grow outside of the human body, meaning identifying individual microbe species is difficult. Advances in DNA technology now means that other identification techniques are possible, but there’s still a long way to go.

Your microbiome could have an even larger impact on health than first thought. Recent evidence suggests that the microbes in your body can affect things such as allergies, obesity and even mental health. You may not notice them, but it’s nice to know that every day you have a few trillion tiny friends looking out for you!

 

Cyclone 03SUPER STORMS

A massive storm called Typhoon Haiyan hit the Philippines earlier in November 2013. One of the largest storms ever observed, it has caused widespread destruction in the island nation.

Typhoons, cyclones and hurricanes are all different names for the same thing: a particularly violent type of tropical storm. Which name it is given depends on where such a storm starts. If it starts around the Americas in the Atlantic and Northeast Pacific ocean, it’s a hurricane. Around Asia, they’re called typhoons. If they form in the South Pacific or Indian ocean they’re referred to as tropical cyclones.

These huge storms start with tropical waters close to the Equator. The warm water heats the air above it. As the air heats it expands in volume and its density decreases, making it rise higher. This creates what is called a low-pressure system. 

The warm air cools as it rises. If it cools fast enough the low-pressure system encourages the formation of thunderstorms – a key cyclone ingredient. Still more things are needed, including the right amount of moisture in the air, and existing atmospheric disturbances. Sometimes, even when all these conditions are present, a cyclone still won’t form. The reasons why might not be obvious, and this makes predicting cyclones difficult. 

Tropical cyclones are given a category, usually based on how strong their winds are. The Australian Bureau of Meteorology (BOM) uses five categories. The most dangerous tropical cyclones, called category 5, have wind gusts of more than 280 kilometres per hour. Other places will have slightly different systems.

Another thing about cyclones that sets them apart is the fact that they are given names. For Australian cyclones, BOM maintains a list of alternating male and female names. When a tropical cyclone forms, it is given the next name on the list. Other naming systems exist, which use things like animal and plant names as well. As cyclones move from one region to another, they might be given multiple names, based on the different systems.

Typhoon Haiyan, also known as Typhoon Yolanda, was a category 5 super typhoon – the worst category. Similarly powerful storms have also affected North America and Australia in recent years. No matter what you call them, cyclones have the potential to be devastating. 

 

SCORCHED EARTH NOT BARREN

Evidence of bushfires burning thousands of years before the arrival of Australia’s Indigenous people can be found in the form of ancient layers of charcoal. The size, severity and frequency of these blazes varied, depending on the climate at the time. The importance of fire to the Australian environment is seen in some plant species, including Banksia and Hakea species, whose seed pods only open under intense heat.

Australian Indigenous communities developed practices involving the intentional starting of controlled fires. Such fires were small, being restricted to patches of vegetation. These fires are called fire mosaics and formed an important part of Indigenous cultures.

Fire mosaics were used in hunting to reveal or flush out animals, but they had other uses as well. These small, controlled fires prevented vegetation from building up. This in turn prevented larger, uncontrolled fires down the track. The regular burning also encouraged a diversity of different types of vegetation.

Given the often destructive nature of fire, and the fact that it was used for hunting animals, it might seem logical to conclude that fire mosaics lead to reductions in animal populations. However, a study in Western Australia has revealed the opposite to be case.

Researchers investigated the fire practices of the Martu people, and counted the number of fresh burrows of a goanna species called the sand monitor. They found that the monitors are most common in the areas they were hunted the most. Rather than decreasing sand monitor populations, the researchers concluded that fire mosaics led to increased numbers of monitors over time.

The researchers suggest that the reason for this is that burning stimulates regrowth of vegetation, and promotes a diversity of niche environments. In turn, this increase in habitat diversity encourages the growth of sand monitor populations.

While this study only looked at one species of goanna, it may also apply to other animal species. At the very least, it highlights that fire is important for life on this hot, dry continent.


THE WORM THAT WANTS TO BE EATEN

Atop a blade of grass waits a baby worm. Sheep graze all around in the South Australian pasture, ripping up mouthfuls of juicy greenery. The worm quivers as a mouth nibbles nearby. Then finally, the moment arrives. In a flurry of teeth and gums the worm is swallowed. But not by a sheep. Instead, it’s eaten by a wild hare.

Introduced to Australia around the same time as rabbits, European hares are larger and have bigger ears to help cool them in hot weather. They are also carriers of the black scour worm commonly found in sheep, according to research by the University of Adelaide.

Parasitic worms are a major source of sheep disease, causing diarrhoea and even death. An adult worm in a sheep’s small intestine lays up to 200 eggs a day, which pass out in poo onto the field. Worms can be killed with a sheep drench – a dose of de-worming chemicals. But some worms will be more resistant to the drench than others. It only takes a few survivors to produce hundreds of eggs that will hatch into drench-resistant worms.

“It’s a major problem worldwide,” says Philip Stott, from the University of Adelaide. “Usually within five or so years of a new chemical drench being developed, somewhere in the world the worms are starting to show signs of resistance.”

Farmers can delay resistance by giving sheep the correct dose of medicine and keeping visiting rams in quarantine. But hares can move easily between paddocks, spreading worms around.

This can be good or bad depending on the circumstances, explains Philip. If the next door neighbour is saving money by only giving sheep half a dose of the drench, those worms will become resistant quickly. “Hares happily hopping from one property to another can spread resistance, grazing on the poorly drenched farm and defecating on the other.”

Hares can also be helpful. By providing a refuge for untreated worms, they can delay resistance. The young of untreated worms compete with drench-resistant worms and eventually outnumber them. When a sheep swallows the waiting baby worms, the parasites are more likely to be killed by the drench next time, making it easier for farmers manage the problem.

 

NOBEL PRIZE FOR CHEMISTRY

Three United States scientists shared the Nobel Prize in Chemistry last week for creating powerful computer programs to simulate chemical reactions. Like flight simulators and climate modelling, these programs calculate and crunch numbers to replicate the real world as closely as possible.

The simulations by Martin Karplus, Michael Levitt and Arieh Warshel straddle two ways of seeing the world: classical physics and quantum mechanics. Classical physics would describe an electron as a particle orbiting around the centre of an atom, like a tiny moon. Quantum mechanics would describe it as a packet of energy, with properties of a wave. 

Simulating quantum mechanics is tough work for computers, as calculating each electron is a huge and complex task. Classical models are easier, but less accurate at modelling areas where molecules ‘dance’ together in a reaction, swapping electrons and energy and atoms.

With these simulations scientists get the best of both worlds. Large chemicals contain lots of atoms, but not all of them are involved in a reaction. Those can be modelled using classical physics, saving the time-consuming quantum mechanics for just those few atoms at the site of the reaction. These models are important tools for chemists, whether they’re looking for new drugs or improving solar cells.

The Nobel Prize in Physics was awarded to François Englert and Peter Higgs for their theoretical mechanism that creates mass in the Universe, which was confirmed by experiments in the Large Hadron Collider that found a Higgs-like boson.

In Medicine, James Rothman, Randy Schekman and Thomas Südhof were recognised for their discovery of how key chemicals such as insulin are transported around cells, which improves our understanding of diabetes.

BRAVE ROVER

On 22 January 2014, Earth received a selfie from Mars Rover Opportunity – proving she is still going strong 10 years after she first landed on Mars!

The image from Opportunity was taken with her panoramic camera, and showed the rover covered in dust. When she landed on Mars in 2004, scientists thought she would survive no more than three months, and were amazed when they celebrated the 10th anniversary of Opportunity on Mars last week. CSIRO’s Dr Paulo de Souza, who worked with NASA on the rover design, said “she is way beyond ‘warranty’. Opportunity is older than many of the cars we drive on Earth and there’s no roadside assistance to help her out!”

Opportunity landed on Mars with her twin, Spirit, a decade ago. The rovers needed power to move and communicate with the Earth, so they were fitted with batteries and solar panels. Scientists thought that dust from Mars would settle on the solar panels – making it difficult for the batteries to recharge – destroying the rovers within 90 days of the mission.

To everyone’s surprise, dust devils or whirlwinds on Mars regularly cleaned the solar panels of any dust, making it possible for their batteries to recharge. Unfortunately, Spirit stopped working six years after she landed when her wheel got stuck in sand. But Opportunity is still trundling over the surface of the red planet, and frequently sends phenomenal findings and photos back to Earth – many of which are received by the Canberra Deep Space Communication Complex in Australia.

Scientists have since sent a more modern rover, Curiosity, to study Mars’ environment and see if it could have supported small life forms in the past. Curiosity, about the size of a minivan, is the largest rover that has been sent to Mars, and her energy source is different to Opportunity. Curiosity gets energy from the radioactive decay of plutonium and scientists have estimated the reactor will last another seven months.

We need water to survive on Earth, and any signs of water on Mars could be a sign that Mars once supported life. The rovers have found evidence of past water in the rocks and minerals. Next steps in the Mars mission are to see if the planet really did have life on it. Opportunity continues to send astonishing images from Mars and – with a little help from the dust devils – could yet see another decade of exploration!

 

THE SCIENCE OF SHARKS

Following a fatal attack off New South Wales, sharks are once again in the spotlight. As tragic as these events are, shark attacks are so rare, scientists aren’t sure why humans are bitten at all

Sharks are found in oceans all around the world – some live near the coast, others in deeper water. Some can even live in freshwater. There are more than 400 species, ranging in size from 17 centimetres to more than 12 metres. Many species are apex predators, and play an important role in marine ecosystems by managing fish populations.

While shark attacks on humans can cause serious injury and even death, they are extremely rare. In Australia there have only been around 50 fatalities in the last 50 years. In 2012, there were only 14 unprovoked attacks. Given that Australians make a total of around 100 million trips to the beach each year, the chances of being bitten by a shark are extremely low.

Because attacks are so rare, marine scientists still aren’t exactly sure why sharks attack in the first place. Some species are more likely to attack than others. Three species – the tiger, white and bull shark – are responsible for most unprovoked attacks on humans. Theories explaining why sharks attack include mistaking humans for prey species such as seals or fish, defending their territory against perceived threats, or simply curiosity.

CSIRO captures, tags, and releases some sharks species, including white and tiger sharks. The tags allow scientists to track the sharks’ movements, and will hopefully lead to a better understanding of their behaviour and interactions with their environment. 

In Australia white sharks and a number of other threatened shark species are protected by law. They may be scary, but sharks are an important part of marine food chain – and losing them could have serious consequences to the ecosystem.

 

moon_centaurus.2GRAVITY CAVITY

Can you imagine a force so powerful that it can pull in light? It may seem unreal, but this force exists in our Universe as a black hole, and nothing can escape its pull! 

Black holes are one of the most powerful and exotic objects in our Universe. They have the ability to slow down time, and most fascinating of all, life may not have been possible without them.

A regular black hole is formed when a large star – at least 20 times heavier than our Sun – runs out of fuel. Without new energy pushing the star out, the star collapses in on itself, shrinking down to a very small size. Eventually the star explodes in a supernova, leaving behind the smallest, densest part of the star. This core keeps collapsing until it is so dense, not even light can escape. However, in the centre of many galaxies are supermassive black holes – more than a million times heavier than our Sun – that grow by drawing in nearby material.

Black holes can be very hard to spot, and astronomers need you to help locate them! Researchers at CSIRO are looking to locate supermassive black holes. They have worked with Zooniverse to develop Radio Galaxy Zoo, a website where you can be a citizen scientist and contribute to research. All you need is a computer with an internet connection, and you can begin your career in astronomy! The instructions are simple and you will quickly learn how to locate black holes by comparing images from infrared and radio telescopes. Satellites and telescopes move through space and take images for you to study. There are many images to explore, and you can talk to the scientists online about your discoveries. So far, 2400 people have helped to classify over 370 000 galaxies, and you can help find more!

There are millions of black holes in our Universe, but only one supermassive black hole in the Milky Way Galaxy. It lies at the centre of the galaxy and is four million times the mass of the Sun. But don’t worry about being pulled in – luckily it is still over 30 000 light years away! 

 

SpiderPHOBIAS

We have long thought that a phobia or fear is caused by a mix of personal experiences and the environment we live in. This idea was challenged recently in research which found that fears could be inherited. Chemical changes in our DNA could make it possible for emotional reactions to be passed on from our parents and grandparents. This means that our fears could be a result of our ancestors’ experiences.

Researchers from the Emory University School of Medicine, Atlanta, designed experiments to test this theory in mice. The mice were trained in the laboratory to fear the smell of cherry blossom. The mice were then bred, and the offspring studied. The young showed signs of fear immediately after their exposure to the smell of cherry blossom, even though they had not been trained to do so. But when the offspring were exposed to unscented cherry blossom, they showed no sign of fear. The experiment showed that the parent mice passed on the fear of the scent of cherry blossom to their offspring.

Fears may be present in an individual before they are even born, and inherited due to trauma experienced by their ancestors. While it’s still early days, these findings could help us understand how information is stored and passed on in the genome. So if you are afraid of heights or think spiders are scary, but don’t know why, maybe your grandparents could explain!

 

BEACH RIP CURRENTS

When waves break at the beach, they create currents. Currents flowing away from the shore are called rip currents, which are important as they allow water to return seaward. The speed and strength of rip currents can vary, and often weak swimmers are in greater danger. However, these currents have been recorded at speeds of 2.4 metres per second, which is faster than an Olympic swimmer!

These characteristics allow rips to quickly carry swimmers away from the shoreline out into the ocean, which can lead swimmers to extreme tiredness, panic, and in severe cases, drowning. Scientists have estimated that rip currents are the leading cause of natural hazard deaths, with approximately 21 human deaths in Australia per year. This figure is higher than the number of deaths caused by cyclones, bushfires, floods and shark attacks combined! 

It can be difficult to identify rip currents, making their presence dangerous for beachgoers. You can scan the beach for signs that help to identify these hazardous currents. Some of these clues include: paths of darker water heading out through the breaking waves, or sandy water, or seaweed and debris flowing out beyond the breakers. 

To prevent getting caught in a rip, always swim between the flags, have someone with you at all times, and look out for signs of a rip current. Should you get caught in a rip, it may be instinct to swim against the current to safety, but this can lead to exhaustion. The best thing to do is remain calm, signal for help, and float with the rip until it weakens enough for you to swim across it to safer water.

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