Australia's Airborne Dentists
A Australians living or traveling in rural and remote areas can face particular difficulties when they need medical care. Hundreds of kilometres from major cities and many hours by road from the closest hospital or clinic, some rural Australians do not have easy access to doctors, nurses and dentists. Organisations such as the Royal Flying Doctor Service (RFDS) have been established to bring health services to outback Australian communities. The RFDS provides free medical care to people who live, work or travel in remote and regional parts of Australia. This non-profit organisation is the oldest and largest airborne health service of its kind in the world, and since 1928 it has used small planes to bring doctors and nurses to some of Australia's most far-away communities.
B In recent years, the RFDS has also started to fly dentists to regional Australia. As well as offering mobile dental clinics, the RFDS offers a range of preventative and educational services. Looking after the teeth of people in remote areas presents special challenges. These include providing care to disparate communities with no established dental facilities, and dealing with higher incidences of other diseases which are linked to, or caused by poor dental health.
C People in remote areas have very infrequent visits by health staff. RFDS dentists might only visit a community once every few months, or sometimes once per year. Because of infrequent dentist visits, patients in these areas often need to put up with their dental problems before they can get treatment; consequently, people in remote areas are more likely to have tooth decay (the blackening and deterioration of teeth) and develop gum and other mouth diseases.
D In some locations that the RFDS visits, there are no suitable dental facilities, so dentists have to bring everything with them. This includes drills, dentists' chairs, portable X-ray machines, and computers for keeping track of patients' treatments. Equipment can weigh up to 100 kilograms, and since the small planes that transport dentists have limited space, dentists cannot always bring everything that they need.
E While dentists in town or city centres can specialise in certain types of treatment, RFDS dentists need to be 'all-rounders'. They need to be able to do all kinds of dental procedures, as they don't have the ability to refer patients to more specialised dentists. Even with their broad experience, there are some services that are particularly challenging for RFDS dentists. For example, dentures (artificial teeth) can be very difficult to provide, as they need to be the right shape and size for the patient, and this requires many visits over a long period of time. As a result, it is not practical to make dentures available.
F Some chronic illnesses are more common in remote communities than in the rest of Australia. These illnesses can in turn lead to a lowered resistance to infection, including gum and other oral infections. As a result, people in outback Australian communities are more likely to experience oral health problems than city folk, and this poses extra challenges for both the dentists and the doctors of the RFDS.
G Because there aren't a lot of dental services in remote areas, people living in these areas also receive less education about good dental hygiene than their city counterparts do. Australians in very remote communities might not be aware of things that people in cities take for granted, such as the importance of daily tooth brushing. Also, basic dental hygiene items such as toothpaste and toothbrushes can be more expensive in outback areas. Many people are on low incomes, meaning they have extra difficulty affording these products. If this is the case, the RFDS supplies these.
H As well as treating patients, RFDS dentists try to focus on preventative oral health and educate their patients on good oral hygiene, such as tooth brushing and flossing. The RFDS also provides mouthguards for young sports players. Playing contact sports, such as rugby league or Australian rules football, can damage young people's teeth, so mouthguards provide protection which prevents accidental injuries.
I Adding fluoride to water supplies has been proven to reduce the incidence of tooth decay in many parts of the world. City dwellers in Australia use water supplies that have been fluoridated, and their rates of tooth decay are lower because of this. In remote areas, it is not practical to fluoridate drinking water supplies, and so people living in these areas are more subject to tooth decay. As a result, it is particularly important that people living in areas without fluoridated water pay special attention to regular brushing of their teeth with fluoridated toothpaste.
J Despite many challenges, the RFDS continues to offer much-needed dental and medical support. Its presence in isolated communities greatly improves the quality of dental health, and supports important oral hygiene and health initiatives.
How are deserts formed?
A A desert refers to a barren section of land, mainly in arid and semi-arid areas, where there is almost no precipitation, and the environment is hostile for any creature to inhabit. Deserts have been classified in a number of ways, generally combining total precipitation, how many days the rainfall occurs, temperature, humidity, and sometimes additional factors. In some places, deserts have clear boundaries marked by rivers, mountains or other landforms, while in other places, there are no clear-cut borders between desert and other landscape features.
B In arid areas where there is not any covering of vegetation protecting the land, sand and dust storms will frequently take place. This phenomenon often occurs along the desert margins instead of within the deserts, where there are already no finer materials left. When a steady wind starts to blow, fine particles on the open ground will begin vibrating. As the wind picks up, some of the particles are lifted into the air. When they fall onto the ground, they hit other particles which will then be jerked into the air in their turn, initiating a chain reaction.
C There has been a tremendous amount of publicity on how severe desertification can be, but the academic community has never agreed on the causes of desertification. A common misunderstanding is that a shortage of precipitation causes the desertification—even the land in some barren areas will soon recover after the rain falls. In fact, more often than not, human activities are responsible for desertification. It might be true that the explosion in world population, especially in developing countries, is the primary cause of soil degradation and desertification. Since the population has become denser, the cultivation of crops has gone into progressively drier areas. It's especially possible for these regions to go through periods of severe drought, which explains why crop failures are common. The raising of most crops requires the natural vegetation cover to be removed first; when crop failures occur, extensive tracts of land are devoid of a plant cover and thus susceptible to wind and water erosion. All through the 1990s, dryland areas went through a population growth of 18.5 per cent, mostly in severely impoverished developing countries.
D Livestock farming in semi-arid areas accelerates the erosion of soil and becomes one of the reasons for advancing desertification. In such areas where the vegetation is dominated by grasses, the breeding of livestock is a major economic activity. Grasses are necessary for anchoring barren topsoil in a dryland area. When a specific field is used to graze an excessive herd, it will experience a loss in vegetation coverage, and the soil will be trampled as well as be pulverised, leaving the topsoil exposed to destructive erosion elements such as winds and unexpected thunderstorms. For centuries, nomads have grazed their flocks and herds to any place where pasture can be found, and oases have offered chances for a more settled way of living. For some nomads, wherever they move to, the desert follows.
E Trees are of great importance when it comes to maintaining topsoil and slowing down the wind speed. In many Asian countries, firewood is the chief fuel used for cooking and heating, which has caused uncontrolled clear-cutting of forests in dryland ecosystems. When too many trees are cut down, windstorms and dust storms tend to occur.
F What's worse, even political conflicts and wars can also contribute to desertification. To escape from the invading enemies, the refugees will move altogether into some of the most vulnerable ecosystems on the planet. They bring along their cultivation traditions, which might not be the right kind of practice for their new settlement.
G In the 20th century, one of the states of America had a large section of farmland that had turned into desert. Since then, actions have been enforced so that such a phenomenon of desertification will not happen again. To avoid the recurrence of desertification, people are encouraged to find other livelihoods which do not rely on traditional land uses, that are not as demanding on local land and natural resources, but can still generate viable income. Such livelihoods include but are not limited to dryland aquaculture for the raising of fish, crustaceans, and industrial compounds derived from microalgae, greenhouse agriculture, and activities that are related to tourism. Another way to prevent the recurrence of desertification is improving the economic prospects of life in city centres and places outside of drylands. Changing the general economic and institutional structures that generate new chances for people to support themselves would alleviate the current pressures accompanying the desertification processes.
H In society nowadays, new technologies are serving as a method to resolve the problems brought by desertification. Satellites have been utilised to investigate the influence that people and livestock have on our planet Earth. Nevertheless, this does not mean that alternative technologies are not needed to help with the problems and process of desertification.
Life on Mars?
Terraforming may sound like something out of science fiction, but some believe it is possible to turn that fiction into fact.
As plans are slowly being drawn up for the first manned mission to Mars, many space travel sceptics are asking one vital question: why go there? Mars is a barren, desolate planet, and with its thin atmosphere and bitterly cold climate, it would appear to be completely unsuitable for human life. Above all, it is a very distant place, and getting there would be an enormous challenge. However, the planet might just hold the key to long-term human survival. With the Earth's population currently at more than seven billion and climbing, we may eventually be forced to look elsewhere in the solar system for somewhere to live. It is just possible that, contrary to photographic evidence, Mars may be more promising than it appears.
Today, Mars is a viciously cold, dry place. However, it does have some things in common with our own planet. For example, it has a daily rotation rate of 24 hours 37 minutes, compared with 23 hours 56 minutes on Earth. It also has an axial tilt of 24 degrees, which is just half a degree more than Earth's, and a gravitational pull one third of Earth's. Furthermore, it holds many of the elements that are required to support life, including carbon and oxygen (in the form of carbon dioxide), nitrogen, and frozen water at its polar ice caps. In fact, if you were to travel back in time several billion years, you would notice some remarkable parallels between the atmosphere on Earth then and Mars today. Back then, Earth was also a lifeless planet; until photosynthetic bacteria developed and began to produce enough oxygen to allow for the development of animal and plant life, our atmosphere also consisted entirely of carbon dioxide and nitrogen.
It comes as no surprise to learn, therefore, that some scientists believe the same process which turned Earth's atmosphere from mostly carbon dioxide into breathable air could be repeated on Mars, but by using technology rather than by letting nature and evolution take its natural course. Terraforming, as this process is known, would initially create a greenhouse effect that would heat the planet, which in turn would create other conditions necessary to provide a suitable living environment for plants and animals. However, it would be a highly challenging undertaking, and the process of terraforming the entire planet into an Earth-like habitat could still take many thousands of years.
Three terraforming methods have been suggested, with the first already under development, albeit for a different purpose. At present, the American space agency NASA is working on a system that will use large mirrors to capture the sun's radiation. This radiation will be used to propel spacecraft through space, removing the need for heavy and expensive rocket fuel. With a few changes, it might be possible to use similar mirrors to reflect the sun's radiation and heat the surface of Mars. Aimed at the planet from a distance of two hundred thousand miles, these enormous mirrors would raise the surface temperature by a few degrees. If they were concentrated on the polar ice caps, they would provide enough heat to melt the polar ice caps and release the carbon dioxide that is believed to be trapped there. Gradually, as the temperature rose, greenhouse gases would be released, and this would create a form of Martian global warming, the first stage in making the planet sustainable for life.
The second method would be to set up greenhouse gas 'factories' in order to raise the temperature of the planet. It is generally accepted that greenhouse gases produced by heavy industry are raising the Earth's temperature. Therefore, by building hundreds of greenhouse-gas emitting factories on Mars, a similar effect could be achieved. Carbon dioxide, methane and other greenhouse gases would be pumped into the Martian atmosphere. The same factories would then produce oxygen by mimicking the natural process of plant photosynthesis: they would inhale the carbon dioxide they produce, and then emit oxygen. The process could be accelerated by sowing the planet's surface with photosynthetic bacteria, which would increase the rate at which oxygen is produced. Eventually, there would be enough oxygen on the planet for humans to breathe using only special apparatus similar to that used by mountain climbers.
The third, and by far the most extreme, method has been proposed by space scientists Robert Zubrin and Christopher McKay. They believe that it would be possible to produce greenhouse gases and water by firing large, ammonia-bearing asteroids at the planet. Each asteroid would weigh about ten billion tons, and would be powered by huge rocket engines which would move it towards Mars at over 10,000 miles per hour. At this speed, it would take each asteroid about ten years to reach its destination. The energy produced by one asteroid slamming into Mars' surface, say Zubrin and McKay, would raise the temperature of the planet by three degrees Celsius and melt about one thousand billion tons of ice at the polar caps. They believe it would take many of these asteroids, and at least fifty years, in order to create a temperate climate and enough water to cover a quarter of the planet's surface.
Terraforming Mars, if it is ever attempted, will be neither cheap nor easy. And it certainly won't be quick: although optimists like Zubrin and McKay say it could be achieved in five or six decades, the reality is that terraforming is more likely to take hundreds or even thousands of years. Furthermore, it will stretch human ingenuity to its limits, and will require levels of will and commitment that have rarely been seen before. The challenge of developing a habitable environment and bringing life to the cold, dry world of Mars is fraught with challenges, but it might just be one that saves the human race.