-
توجه: در صورتی که از کاربران قدیمی ایران انجمن هستید و امکان ورود به سایت را ندارید، میتوانید با آیدی altin_admin@ در تلگرام تماس حاصل نمایید.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
نمونه سوالات آزمون IELTS
- شروع کننده موضوع melika
- تاریخ شروع
Reading 1
Why Risks Can Go Wrong
Human intuition is a bad guide to handling risk
Paragraph A
People make terrible decisions about the future. The evidence is all around, from their investments in the stock markets to the way they run their businesses. In fact, people are consistently bad at dealing with uncertainty, underestimating some kinds of risk and overestimating others. Surely there must be a better way than using intuition?
Paragraph B
In the 1960s a young American research psychologist, Daniel Kahneman, became interested in people's inability to make logical decisions. That launched him on a career to show just how irrationally people behave in practice. When Kahneman and his colleagues first started work, the idea of applying psychological insights to economics and business decisions was seen as rather bizarre. But in the past decade the fields of behavioural finance and behavioural economics have blossomed, and in 2002 Kahneman shared a Nobel prize in economics for his work. Today he is in demand by business organizations and international banking companies. But, he says, there are plenty of institutions that still fail to understand the roots of their poor decisions. He claims that, far from being random, these mistakes are systematic and predictable.
Paragraph C
One common cause of problems in decision-making is over-optimism. Ask most people about the future, and they will see too much blue sky ahead, even if past experience suggests otherwise. Surveys have shown that people's forecasts of future stock market movements are far more optimistic than past long-term returns would justify. The same goes for their hopes of ever-rising prices for their homes or doing well in games of chance. Such optimism can be useful for managers or sportsmen, and sometimes turns into a self-fulfilling prophecy. But most of the time it results in wasted effort and dashed hopes. Kahneman's work points to three types of over-confidence. First, people tend to exaggerate their own skill and prowess; in polls, far fewer than half the respondents admit to having below-average skills in, say, driving. Second, they overestimate the amount of control they have over the future, forgetting about luck and chalking up success solely to skill. And third, in competitive pursuits such as dealing on shares, they forget that they have to judge their skills against those of the competition.
Paragraph D
Another source of wrong decisions is related to the decisive effect of the initial meeting, particularly in negotiations over money. This is referred to as the 'anchor effect'. Once a figure has been mentioned, it takes a strange hold over the human mind. The asking price quoted in a house sale, for example, tends to become accepted by all parties as the 'anchor' around which negotiations take place. Much the same goes for salary negotiations or mergers and acquisitions. If nobody has much information to go on, a figure can provide comfort - even though it may lead to a terrible mistake.
Paragraph E
In addition, mistakes may arise due to stubbornness. No one likes to abandon a cherished belief, and the earlier a decision has been taken, the harder it is to abandon it. Drug companies must decide early to cancel a failing research project to avoid wasting money, but may find it difficult to admit they have made a mistake. In the same way, analysts may have become wedded early to a single explanation that coloured their perception. A fresh eye always helps.
Paragraph F
People also tend to put a lot of emphasis on things they have seen and experienced themselves, which may not be the best guide to decision-making. For example, somebody may buy an overvalued share because a relative has made thousands on it, only to get his fingers burned. In finance, too much emphasis on information close at hand helps to explain the tendency by most investors to invest only within the country they live in. Even though they know that diversification is good for their portfolio, a large majority of both Americans and Europeans invest far too heavily in the shares of their home countries. They would be much better off spreading their risks more widely.
Paragraph G
More information is helpful in making any decision but, says Kahneman, people spend proportionally too much time on small decisions and not enough on big ones. They need to adjust the balance. During the boom years, some companies put as much effort into planning their office party as into considering strategic mergers.
Paragraph H
Finally, crying over spilled milk is not just a waste of time; it also often colours people's perceptions of the future. Some stock market investors trade far too frequently because they are chasing the returns on shares they wish they had bought earlier.
Paragraph I
Kahneman reckons that some types of businesses are much better than others at dealing with risk. Pharmaceutical companies, which are accustomed to many failures and a few big successes in their drug-discovery programmes, are fairly rational about their risk-taking. But banks, he says, have a long way to go. They may take big risks on a few huge loans, but are extremely cautious about their much more numerous loans to small businesses, many of which may be less risky than the big ones. And the research has implications for governments too. They face a whole range of sometimes conflicting political pressures, which means they are even more likely to take irrational decisions
Why Risks Can Go Wrong
Human intuition is a bad guide to handling risk
Paragraph A
People make terrible decisions about the future. The evidence is all around, from their investments in the stock markets to the way they run their businesses. In fact, people are consistently bad at dealing with uncertainty, underestimating some kinds of risk and overestimating others. Surely there must be a better way than using intuition?
Paragraph B
In the 1960s a young American research psychologist, Daniel Kahneman, became interested in people's inability to make logical decisions. That launched him on a career to show just how irrationally people behave in practice. When Kahneman and his colleagues first started work, the idea of applying psychological insights to economics and business decisions was seen as rather bizarre. But in the past decade the fields of behavioural finance and behavioural economics have blossomed, and in 2002 Kahneman shared a Nobel prize in economics for his work. Today he is in demand by business organizations and international banking companies. But, he says, there are plenty of institutions that still fail to understand the roots of their poor decisions. He claims that, far from being random, these mistakes are systematic and predictable.
Paragraph C
One common cause of problems in decision-making is over-optimism. Ask most people about the future, and they will see too much blue sky ahead, even if past experience suggests otherwise. Surveys have shown that people's forecasts of future stock market movements are far more optimistic than past long-term returns would justify. The same goes for their hopes of ever-rising prices for their homes or doing well in games of chance. Such optimism can be useful for managers or sportsmen, and sometimes turns into a self-fulfilling prophecy. But most of the time it results in wasted effort and dashed hopes. Kahneman's work points to three types of over-confidence. First, people tend to exaggerate their own skill and prowess; in polls, far fewer than half the respondents admit to having below-average skills in, say, driving. Second, they overestimate the amount of control they have over the future, forgetting about luck and chalking up success solely to skill. And third, in competitive pursuits such as dealing on shares, they forget that they have to judge their skills against those of the competition.
Paragraph D
Another source of wrong decisions is related to the decisive effect of the initial meeting, particularly in negotiations over money. This is referred to as the 'anchor effect'. Once a figure has been mentioned, it takes a strange hold over the human mind. The asking price quoted in a house sale, for example, tends to become accepted by all parties as the 'anchor' around which negotiations take place. Much the same goes for salary negotiations or mergers and acquisitions. If nobody has much information to go on, a figure can provide comfort - even though it may lead to a terrible mistake.
Paragraph E
In addition, mistakes may arise due to stubbornness. No one likes to abandon a cherished belief, and the earlier a decision has been taken, the harder it is to abandon it. Drug companies must decide early to cancel a failing research project to avoid wasting money, but may find it difficult to admit they have made a mistake. In the same way, analysts may have become wedded early to a single explanation that coloured their perception. A fresh eye always helps.
Paragraph F
People also tend to put a lot of emphasis on things they have seen and experienced themselves, which may not be the best guide to decision-making. For example, somebody may buy an overvalued share because a relative has made thousands on it, only to get his fingers burned. In finance, too much emphasis on information close at hand helps to explain the tendency by most investors to invest only within the country they live in. Even though they know that diversification is good for their portfolio, a large majority of both Americans and Europeans invest far too heavily in the shares of their home countries. They would be much better off spreading their risks more widely.
Paragraph G
More information is helpful in making any decision but, says Kahneman, people spend proportionally too much time on small decisions and not enough on big ones. They need to adjust the balance. During the boom years, some companies put as much effort into planning their office party as into considering strategic mergers.
Paragraph H
Finally, crying over spilled milk is not just a waste of time; it also often colours people's perceptions of the future. Some stock market investors trade far too frequently because they are chasing the returns on shares they wish they had bought earlier.
Paragraph I
Kahneman reckons that some types of businesses are much better than others at dealing with risk. Pharmaceutical companies, which are accustomed to many failures and a few big successes in their drug-discovery programmes, are fairly rational about their risk-taking. But banks, he says, have a long way to go. They may take big risks on a few huge loans, but are extremely cautious about their much more numerous loans to small businesses, many of which may be less risky than the big ones. And the research has implications for governments too. They face a whole range of sometimes conflicting political pressures, which means they are even more likely to take irrational decisions
Reading 2
There has always been a sense in which America and Europe owned film. They invented it at the end of the nineteenth century in unfashionable places like New Jersey, Leeds and the suburbs of Lyons. At first, they saw their clumsy new camera-projectors merely as more profitable versions of Victorian lantern shows, mechanical curiosities which might have a use as a sideshow at a funfair. Then the best of the pioneers looked beyond the fairground properties of their invention. A few directors, now mostly forgotten, saw that the flickering new medium was more than just a diversion. This crass commercial invention gradually began to evolve as an art. D W Griffith in California glimpsed its grace, German directors used it as an analogue to the human mind and the modernising city, Soviets emphasised its agitational and intellectual properties, and the Italians reconfigured it on an operatic scale.
So heady were these first decades of cinema that America and Europe can be forgiven for assuming that they were the only game in town. In less than twenty years western cinema had grown out of all recognition; its unknowns became the most famous people in the world; it made millions. It never occurred to its financial backers that another continent might borrow their magic box and make it its own. But film industries were emerging in Shanghai, Bombay and Tokyo, some of which would outgrow those in the west.
Between 1930 and 1935, China produced more than 500 films, mostly conventionally made in studios in Shanghai, without soundtracks. China's best directors - Bu Wancang and Yuan Muzhi - introduced elements of realism to their stories. The Peach Girl (1931) and Street Angel (1937) are regularly voted among the best ever made in the country.
India followed a different course. In the west, the arrival of talkies gave birth to a new genre - the musical - but in India, every one of the 5000 films made between 1931 and the mid-1950s had musical interludes. The films were stylistically more wide ranging than the western musical, encompassing realism and escapist dance within individual sequences, and they were often three hours long rather than Hollywood's 90 minutes. The cost of such productions resulted in a distinctive national style of cinema. They were often made in Bombay, the centre of what is now known as 'Bollywood'. Performed in Hindi (rather than any of the numerous regional languages), they addressed social and peasant themes in an optimistic and romantic way and found markets in the Middle East, Africa and the Soviet Union.
In Japan, the film industry did not rival India's in size but was unusual in other ways. Whereas in Hollywood the producer was the central figure, in Tokyo the director chose the stories and hired the producer and actors. The model was that of an artist and his studio of apprentices. Employed by a studio as an assistant, a future director worked with senior figures, learned his craft, gained authority, until promoted to director with the power to select screenplays and performers. In the 1930s and 40s, this freedom of the director led to the production of some of Asia's finest films.
The films of Kenji Mizoguchi were among the greatest of these. Mizoguchi's films were usually set in the nineteenth century and analysed the way in which the lives of the female characters whom he chose as his focus were constrained by the society of the time. From Osaka Elegy (1936) to Ugetsu Monogatari (1953) and beyond, he evolved a sinuous way of moving his camera in and around a scene, advancing towards significant details but often retreating at moments of confrontation or strong feeling. No one had used the camera with such finesse before.
Even more important for film history, however, is the work of the great Ozu. Where Hollywood cranked up drama, Ozu avoided it. His camera seldom moved. It nestled at seated height, framing people square on, listening quietly to their words. Ozu rejected the conventions of editing, cutting not on action, as is usually done in the west, but for visual balance. Even more strikingly, Ozu regularly cut away from his action to a shot of a tree or a kettle or clouds, not to establish a new location but as a moment of repose. Many historians now compare such 'pillow shots' to the Buddhist idea that mu - empty space or nothing - is itself an element of composition.
As the art form most swayed by money and market, cinema would appear to be too busy to bother with questions of philosophy. The Asian nations proved and are still proving that this is not the case. Just as deep ideas about individual freedom have led to the aspirational cinema of Hollywood, so it is the beliefs which underlie cultures such as those of China and Japan that explain the distinctiveness of Asian cinema at its best. Yes, these films are visually striking, but it is their different sense of what a person is, and what space and action are, which makes them new to western eyes
There has always been a sense in which America and Europe owned film. They invented it at the end of the nineteenth century in unfashionable places like New Jersey, Leeds and the suburbs of Lyons. At first, they saw their clumsy new camera-projectors merely as more profitable versions of Victorian lantern shows, mechanical curiosities which might have a use as a sideshow at a funfair. Then the best of the pioneers looked beyond the fairground properties of their invention. A few directors, now mostly forgotten, saw that the flickering new medium was more than just a diversion. This crass commercial invention gradually began to evolve as an art. D W Griffith in California glimpsed its grace, German directors used it as an analogue to the human mind and the modernising city, Soviets emphasised its agitational and intellectual properties, and the Italians reconfigured it on an operatic scale.
So heady were these first decades of cinema that America and Europe can be forgiven for assuming that they were the only game in town. In less than twenty years western cinema had grown out of all recognition; its unknowns became the most famous people in the world; it made millions. It never occurred to its financial backers that another continent might borrow their magic box and make it its own. But film industries were emerging in Shanghai, Bombay and Tokyo, some of which would outgrow those in the west.
Between 1930 and 1935, China produced more than 500 films, mostly conventionally made in studios in Shanghai, without soundtracks. China's best directors - Bu Wancang and Yuan Muzhi - introduced elements of realism to their stories. The Peach Girl (1931) and Street Angel (1937) are regularly voted among the best ever made in the country.
India followed a different course. In the west, the arrival of talkies gave birth to a new genre - the musical - but in India, every one of the 5000 films made between 1931 and the mid-1950s had musical interludes. The films were stylistically more wide ranging than the western musical, encompassing realism and escapist dance within individual sequences, and they were often three hours long rather than Hollywood's 90 minutes. The cost of such productions resulted in a distinctive national style of cinema. They were often made in Bombay, the centre of what is now known as 'Bollywood'. Performed in Hindi (rather than any of the numerous regional languages), they addressed social and peasant themes in an optimistic and romantic way and found markets in the Middle East, Africa and the Soviet Union.
In Japan, the film industry did not rival India's in size but was unusual in other ways. Whereas in Hollywood the producer was the central figure, in Tokyo the director chose the stories and hired the producer and actors. The model was that of an artist and his studio of apprentices. Employed by a studio as an assistant, a future director worked with senior figures, learned his craft, gained authority, until promoted to director with the power to select screenplays and performers. In the 1930s and 40s, this freedom of the director led to the production of some of Asia's finest films.
The films of Kenji Mizoguchi were among the greatest of these. Mizoguchi's films were usually set in the nineteenth century and analysed the way in which the lives of the female characters whom he chose as his focus were constrained by the society of the time. From Osaka Elegy (1936) to Ugetsu Monogatari (1953) and beyond, he evolved a sinuous way of moving his camera in and around a scene, advancing towards significant details but often retreating at moments of confrontation or strong feeling. No one had used the camera with such finesse before.
Even more important for film history, however, is the work of the great Ozu. Where Hollywood cranked up drama, Ozu avoided it. His camera seldom moved. It nestled at seated height, framing people square on, listening quietly to their words. Ozu rejected the conventions of editing, cutting not on action, as is usually done in the west, but for visual balance. Even more strikingly, Ozu regularly cut away from his action to a shot of a tree or a kettle or clouds, not to establish a new location but as a moment of repose. Many historians now compare such 'pillow shots' to the Buddhist idea that mu - empty space or nothing - is itself an element of composition.
As the art form most swayed by money and market, cinema would appear to be too busy to bother with questions of philosophy. The Asian nations proved and are still proving that this is not the case. Just as deep ideas about individual freedom have led to the aspirational cinema of Hollywood, so it is the beliefs which underlie cultures such as those of China and Japan that explain the distinctiveness of Asian cinema at its best. Yes, these films are visually striking, but it is their different sense of what a person is, and what space and action are, which makes them new to western eyes
Reading 3
Quiet Roads Ahead
The roar of passing vehicles could soon be a thing of the past
Paragraph A
The noise produced by busy roads is a growing problem. While vehicle designers have worked hard to quieten engines, they have been less successful elsewhere. The sound created by the tyres on the surface of the road now accounts for more than half the noise that vehicles create, and as road building and car sales continue to boom - particularly in Asia and the US - this is turning into a global issue.
Paragraph B
According to the World Health Organization, exposure to noise from road traffic over long periods can lead to stress-related health problems. And where traffic noise exceeds a certain threshold, road builders have to spend money erecting sound barriers and installing double glazing in blighted homes. Houses become harder to sell where environmental noise is high, and people are not as efficient or productive at work.
Paragraph C
Already, researchers in the Netherlands - one of the most densely populated countries in the world - are working to develop techniques for silencing the roads. In the next five years the Dutch government aims to have reduced noise levels from the country's road surfaces by six decibels overall. Dutch mechanical engineer Ard Kuijpers has come up with one of the most promising, and radical, ideas. He set out to tackle the three most important factors: surface texture, hardness and ability to absorb sound.
Paragraph D
The rougher the surface, the more likely it is that a tyre will vibrate and create noise. Road builders usually eliminate bumps on freshly laid asphalt with heavy rollers, but Kuijpers has developed a method of road building that he thinks can create the ultimate quiet road. His secret is a special mould 3 metres wide and 50 metres long. Hot asphalt, mixed with small stones, is spread into the mould by a railmounted machine which flattens the asphalt mix with a roller. When it sets, the 10-millimetre-thick sheet has a surface smoother than anything that can be achieved by conventional methods.
Paragraph E
To optimise the performance of his road surface - to make it hard wearing yet soft enough to snuff out vibrations - he then adds another layer below the asphalt. This consists of a 30-millimetre-thick layer of rubber, mixed with stones which are larger than those in the layer above. 'It's like a giant mouse mat, making the road softer,' says Kuijpers.
Paragraph F
The size of the stones used in the two layers is important, since they create pores of a specific size in the road surface. Those used in the top layer are just 4 or 5 millimetres across, while the ones below are approximately twice that size - about 9 millimetres. Kuijpers says the surface can absorb any air that is passing through a tyre's tread (the indentations or ridges on the surface of a tyre), damping oscillations that would otherwise create noise. And in addition they make it easier for the water to drain away, which can make the road safer in wet weather.
Paragraph G
Compared with the complex manufacturing process, laying the surface is quite simple. It emerges from the factory rolled, like a carpet, onto a drum 1.5 metres in diameter. On site, it is unrolled and stuck onto its foundation with bitumen. Even the white lines are applied in the factory.
Paragraph H
The foundation itself uses an even more sophisticated technique to reduce noise further. It consists of a sound-absorbing concrete base containing flask-shaped slots up to 10 millimetres wide and 30 millimetres deep that are open at the top and sealed at the lower end. These cavities act like Helmholtz resonators - when sound waves of specific frequencies enter the top of a flask, they set up resonances inside and the energy of the sound dissipates into the concrete as heat. The cavities play another important role: they help to drain water that seeps through from the upper surface. This flow will help flush out waste material and keep the pores in the outer layers clear.
Paragraph I
Kuijpers can even control the sounds that his resonators absorb, simply by altering their dimensions. This could prove especially useful since different vehicles produce noise at different frequencies. Car tyres peak at around 1000 hertz, for example, but trucks generate lower-frequency noise at around 600 hertz. By varying the size of the Kuijpers resonators, it is possible to control which frequencies the concrete absorbs. On large highways, trucks tend to use the inside lane, so resonators here could be tuned to absorb sounds at around 600 hertz while those in other lanes could deal with higher frequency noise from cars.
Paragraph J
Kuijpers believes he can cut noise by five decibels compared to the quietest of today's roads. He has already tested a l00-metre-long section of his road on a motorway near Apeldoorn, and Dutch construction company Heijmans is discussing the location of the next roll-out road with the country's government. The success of Kuijpers' design will depend on how much it eventually costs. But for those affected by traffic noise there is hope of quieter times ahead
Quiet Roads Ahead
The roar of passing vehicles could soon be a thing of the past
Paragraph A
The noise produced by busy roads is a growing problem. While vehicle designers have worked hard to quieten engines, they have been less successful elsewhere. The sound created by the tyres on the surface of the road now accounts for more than half the noise that vehicles create, and as road building and car sales continue to boom - particularly in Asia and the US - this is turning into a global issue.
Paragraph B
According to the World Health Organization, exposure to noise from road traffic over long periods can lead to stress-related health problems. And where traffic noise exceeds a certain threshold, road builders have to spend money erecting sound barriers and installing double glazing in blighted homes. Houses become harder to sell where environmental noise is high, and people are not as efficient or productive at work.
Paragraph C
Already, researchers in the Netherlands - one of the most densely populated countries in the world - are working to develop techniques for silencing the roads. In the next five years the Dutch government aims to have reduced noise levels from the country's road surfaces by six decibels overall. Dutch mechanical engineer Ard Kuijpers has come up with one of the most promising, and radical, ideas. He set out to tackle the three most important factors: surface texture, hardness and ability to absorb sound.
Paragraph D
The rougher the surface, the more likely it is that a tyre will vibrate and create noise. Road builders usually eliminate bumps on freshly laid asphalt with heavy rollers, but Kuijpers has developed a method of road building that he thinks can create the ultimate quiet road. His secret is a special mould 3 metres wide and 50 metres long. Hot asphalt, mixed with small stones, is spread into the mould by a railmounted machine which flattens the asphalt mix with a roller. When it sets, the 10-millimetre-thick sheet has a surface smoother than anything that can be achieved by conventional methods.
Paragraph E
To optimise the performance of his road surface - to make it hard wearing yet soft enough to snuff out vibrations - he then adds another layer below the asphalt. This consists of a 30-millimetre-thick layer of rubber, mixed with stones which are larger than those in the layer above. 'It's like a giant mouse mat, making the road softer,' says Kuijpers.
Paragraph F
The size of the stones used in the two layers is important, since they create pores of a specific size in the road surface. Those used in the top layer are just 4 or 5 millimetres across, while the ones below are approximately twice that size - about 9 millimetres. Kuijpers says the surface can absorb any air that is passing through a tyre's tread (the indentations or ridges on the surface of a tyre), damping oscillations that would otherwise create noise. And in addition they make it easier for the water to drain away, which can make the road safer in wet weather.
Paragraph G
Compared with the complex manufacturing process, laying the surface is quite simple. It emerges from the factory rolled, like a carpet, onto a drum 1.5 metres in diameter. On site, it is unrolled and stuck onto its foundation with bitumen. Even the white lines are applied in the factory.
Paragraph H
The foundation itself uses an even more sophisticated technique to reduce noise further. It consists of a sound-absorbing concrete base containing flask-shaped slots up to 10 millimetres wide and 30 millimetres deep that are open at the top and sealed at the lower end. These cavities act like Helmholtz resonators - when sound waves of specific frequencies enter the top of a flask, they set up resonances inside and the energy of the sound dissipates into the concrete as heat. The cavities play another important role: they help to drain water that seeps through from the upper surface. This flow will help flush out waste material and keep the pores in the outer layers clear.
Paragraph I
Kuijpers can even control the sounds that his resonators absorb, simply by altering their dimensions. This could prove especially useful since different vehicles produce noise at different frequencies. Car tyres peak at around 1000 hertz, for example, but trucks generate lower-frequency noise at around 600 hertz. By varying the size of the Kuijpers resonators, it is possible to control which frequencies the concrete absorbs. On large highways, trucks tend to use the inside lane, so resonators here could be tuned to absorb sounds at around 600 hertz while those in other lanes could deal with higher frequency noise from cars.
Paragraph J
Kuijpers believes he can cut noise by five decibels compared to the quietest of today's roads. He has already tested a l00-metre-long section of his road on a motorway near Apeldoorn, and Dutch construction company Heijmans is discussing the location of the next roll-out road with the country's government. The success of Kuijpers' design will depend on how much it eventually costs. But for those affected by traffic noise there is hope of quieter times ahead
Reading 4
Sustainable Architecture - Lessons from the Ant
Termite mounds were the inspiration for an innovative design in sustainable living
Africa owes its termite mounds a lot. Trees and shrubs take root in them. Prospectors mine them, looking for specks of gold carried up by termites from hundreds of metres below. And of course, they are a special treat to aardvarks and other insectivores.
Now, Africa is paying an offbeat tribute to these towers of mud. The extraordinary Eastgate Building in Harare, Zimbabwe's capital city, is said to be the only one in the world to use the same cooling and heating principles as the termite mound.
Termites in Zimbabwe build gigantic mounds inside which they farm a fungus that is their primary food source. This must be kept at exactly 30.5C, while the temperatures on the African veld outside can range from 1.5C at night - only just above freezing - to a baking hot 40C during the day. The termites achieve this remarkable feat by building a system of vents in the mound. Those at the base lead down into chambers cooled by wet mud carried up from water tables far below, and others lead up through a flue to the peak of the mound. By constantly opening and closing these heating and cooling vents over the course of the day the termites succeed in keeping the temperature constant in spite of the wide fluctuations outside.
Architect Mick Pearce used precisely the same strategy when designing the Eastgate Building, which has no air conditioning and virtually no heating. The building - the country's largest commercial and shopping complex - uses less than 10% of the energy of a conventional building its size. These efficiencies translated directly to the bottom line: the Eastgate's owners saved $3.5 million on a $36 million building because an air-conditioning plant didn't have to be imported. These savings were also passed on to tenants: rents are 20% lower than in a new building next door.
The complex is actually two buildings linked by bridges across a shady, glass-roofed atrium open to the breezes. Fans suck fresh air in from the atrium, blow it upstairs through hollow spaces under the floors and from there into each office through baseboard vents. As it rises and warms, it is drawn out via ceiling vents and finally exits through forty-eight brick chimneys.
To keep the harsh, high veld sun from heating the interior, no more than 25% of the outside is glass, and all the windows are screened by cement arches that jut out more than a metre.
During summer's cool nights, big fans flush air through the building seven times an hour to chill the hollow floors. By day, smaller fans blow two changes of air an hour through the building, to circulate the air which has been in contact with the cool floors. For winter days, there are small heaters in the vents.
This is all possible only because Harare is 1600 feet above sea level, has cloudless skies, little humidity and rapid temperature swings - days as warm as 31C commonly drop to 14C at night. 'You couldn't do this in New York, with its fantastically hot summers and fantastically cold winters,' Pearce said. But then his eyes lit up at the challenge. 'Perhaps you could store the summer's heat in water somehow ... .'
The engineering firm of Ove Arup & Partners, which worked with him on the design, monitors daily temperatures outside, under the floors and at knee, desk and ceiling level. Ove Arup's graphs show that the temperature of the building has generally stayed between 23C and 25C, with the exception of the annual hot spell just before the summer rains in October, and three days in November, when a janitor accidentally switched off the fans at night. The atrium, which funnels the winds through, can be much cooler. And the air is fresh - far more so than in air-conditioned buildings, where up to 30% of the air is recycled.
Pearce, disdaining smooth glass skins as 'igloos in the Sahara', calls his building, with its exposed girders and pipes, 'spiky'. The design of the entrances is based on the porcupine-quill headdresses of the local Shona tribe. Elevators are designed to look like the mineshaft cages used in Zimbabwe's diamond mines. The shape of the fan covers, and the stone used in their construction, are echoes of Great Zimbabwe, the ruins that give the country its name.
Standing on a roof catwalk, peering down inside at people as small as termites below, Pearce said he hoped plants would grow wild in the atrium and pigeons and bats would move into it, like that termite fungus, further extending the whole 'organic machine' metaphor. The architecture, he says, is a regionalised style that responds to the biosphere, to the ancient traditional stone architecture of Zimbabwe's past, and to local human resources
Sustainable Architecture - Lessons from the Ant
Termite mounds were the inspiration for an innovative design in sustainable living
Africa owes its termite mounds a lot. Trees and shrubs take root in them. Prospectors mine them, looking for specks of gold carried up by termites from hundreds of metres below. And of course, they are a special treat to aardvarks and other insectivores.
Now, Africa is paying an offbeat tribute to these towers of mud. The extraordinary Eastgate Building in Harare, Zimbabwe's capital city, is said to be the only one in the world to use the same cooling and heating principles as the termite mound.
Termites in Zimbabwe build gigantic mounds inside which they farm a fungus that is their primary food source. This must be kept at exactly 30.5C, while the temperatures on the African veld outside can range from 1.5C at night - only just above freezing - to a baking hot 40C during the day. The termites achieve this remarkable feat by building a system of vents in the mound. Those at the base lead down into chambers cooled by wet mud carried up from water tables far below, and others lead up through a flue to the peak of the mound. By constantly opening and closing these heating and cooling vents over the course of the day the termites succeed in keeping the temperature constant in spite of the wide fluctuations outside.
Architect Mick Pearce used precisely the same strategy when designing the Eastgate Building, which has no air conditioning and virtually no heating. The building - the country's largest commercial and shopping complex - uses less than 10% of the energy of a conventional building its size. These efficiencies translated directly to the bottom line: the Eastgate's owners saved $3.5 million on a $36 million building because an air-conditioning plant didn't have to be imported. These savings were also passed on to tenants: rents are 20% lower than in a new building next door.
The complex is actually two buildings linked by bridges across a shady, glass-roofed atrium open to the breezes. Fans suck fresh air in from the atrium, blow it upstairs through hollow spaces under the floors and from there into each office through baseboard vents. As it rises and warms, it is drawn out via ceiling vents and finally exits through forty-eight brick chimneys.
To keep the harsh, high veld sun from heating the interior, no more than 25% of the outside is glass, and all the windows are screened by cement arches that jut out more than a metre.
During summer's cool nights, big fans flush air through the building seven times an hour to chill the hollow floors. By day, smaller fans blow two changes of air an hour through the building, to circulate the air which has been in contact with the cool floors. For winter days, there are small heaters in the vents.
This is all possible only because Harare is 1600 feet above sea level, has cloudless skies, little humidity and rapid temperature swings - days as warm as 31C commonly drop to 14C at night. 'You couldn't do this in New York, with its fantastically hot summers and fantastically cold winters,' Pearce said. But then his eyes lit up at the challenge. 'Perhaps you could store the summer's heat in water somehow ... .'
The engineering firm of Ove Arup & Partners, which worked with him on the design, monitors daily temperatures outside, under the floors and at knee, desk and ceiling level. Ove Arup's graphs show that the temperature of the building has generally stayed between 23C and 25C, with the exception of the annual hot spell just before the summer rains in October, and three days in November, when a janitor accidentally switched off the fans at night. The atrium, which funnels the winds through, can be much cooler. And the air is fresh - far more so than in air-conditioned buildings, where up to 30% of the air is recycled.
Pearce, disdaining smooth glass skins as 'igloos in the Sahara', calls his building, with its exposed girders and pipes, 'spiky'. The design of the entrances is based on the porcupine-quill headdresses of the local Shona tribe. Elevators are designed to look like the mineshaft cages used in Zimbabwe's diamond mines. The shape of the fan covers, and the stone used in their construction, are echoes of Great Zimbabwe, the ruins that give the country its name.
Standing on a roof catwalk, peering down inside at people as small as termites below, Pearce said he hoped plants would grow wild in the atrium and pigeons and bats would move into it, like that termite fungus, further extending the whole 'organic machine' metaphor. The architecture, he says, is a regionalised style that responds to the biosphere, to the ancient traditional stone architecture of Zimbabwe's past, and to local human resources
Reading 5
Natural Choice
Coffee and chocolate
What's the connection between your morning coffee, wintering North American birds and the cool shade of a tree? Actually, quite a lot, says Simon Birch.
When scientists from London's Natural History Museum descended on the coffee farms of the tiny Central American republic of El Salvador, they were astonished to find such diversity of insect and plant species. During 18 months' work on 12 farms, they found a third more species of parasitic wasp than are known to exist in the whole country of Costa Rica. They described four new species and are aware of a fifth. On 24 farms they found nearly 300 species of tree - when they had expected to find about 100.
El Salvador has lost much of its natural forest, with coffee farms covering nearly 10% of the country. Most of them use the 'shade-grown' method of production, which utilises a semi-natural forest ecosystem. Alex Munro, the museum's botanist on the expedition, says: 'Our findings amazed our insect specialist. There's a very sophisticated food web present. The wasps, for instance, may depend on specific species of tree.'
It's the same the world over. Species diversity is much higher where coffee is grown in shade conditions. In addition, coffee (and chocolate) is usually grown in tropical rainforest regions that are biodiversity hotspots. 'These habitats support up to 70% of the planet's plant and animal species, and so the production methods of cocoa and coffee can have a hugely significant impact,' explains Dr Paul Donald of the Royal Society for the Protection of Birds.
So what does 'shade-grown' mean, and why is it good for wildlife? Most of the world's coffee is produced by poor farmers in the developing world. Traditionally they have grown coffee (and cocoa) under the shade of selectively thinned tracts of rain forest in a genuinely sustainable form of farming. Leaf fall from the canopy provides a supply of nutrients and acts as a mulch that suppresses weeds. The insects that live in the canopy pollinate the cocoa and coffee and prey on pests. The trees also provide farmers with fruit and wood for fuel.
'Bird diversity in shade-grown coffee plantations rivals that found in natural forests in the same region,' says Robert Rice from the Smithsonian Migratory Bird Center. In Ghana, West Africa, - one of the world's biggest producers of cocoa - 90% of the cocoa is grown under shade, and these forest plantations are a vital habitat for wintering European migrant birds. In the same way, the coffee forests of Central and South America are a refuge for wintering North American migrants.
More recently, a combination of the collapse in the world market for coffee and cocoa and a drive to increase yields by producer countries has led to huge swathes of shade-grown coffee and cocoa being cleared to make way for a highly intensive, monoculture pattern of production known as 'full sun'. But this system not only reduces the diversity of flora and fauna, it also requires huge amounts of pesticides and fertilisers. In Cote d'Ivoire, which produces more than half the world's cocoa, more than a third of the crop is now grown in full-sun conditions.
The loggers have been busy in the Americas too, where nearly 70% of all Colombian coffee is now produced using full-sun production. One study carried out in Colombia and Mexico found that, compared with shade coffee, full-sun plantations have 95% fewer species of birds.
In El Salvador, Alex Munro says shade-coffee farms have a cultural as well as ecological significance and people are not happy to see them go. But the financial pressures are great, and few of these coffee farms make much money. 'One farm we studied, a cooperative of 100 families, made just $10,000 a year - $100 per family - and that's not taking labour costs into account.'
The loss of shade-coffee forests has so alarmed a number of North American wildlife organisations that they're now harnessing consumer power to help save these threatened habitats. They are promoting a 'certification' system that can indicate to consumers that the beans have been grown on shade plantations. Bird-friendly coffee, for instance, is marketed by the Smithsonian Migratory Bird Center. The idea is that the small extra cost is passed directly on to the coffee farmers as a financial incentive to maintain their shade-coffee farms.
Not all conservationists agree with such measures, however. Some say certification could be leading to the loss - not preservation - of natural forests. John Rappole of the Smithsonian Conservation and Research Center, for example, argues that shade-grown marketing provides 'an incentive to convert existing areas of primary forest that are too remote or steep to be converted profitably to other forms of cultivation into shade-coffee plantations'.
Other conservationists, such as Stacey Philpott and colleagues, argue the case for shade coffee. But there are different types of shade growing. Those used by subsistence farmers are virtually identical to natural forest (and have a corresponding diversity), while systems that use coffee plants as the understorey and cacao or citrus trees as the overstorey may be no more diverse than full-sun farms. Certification procedures need to distinguish between the two, and Ms Philpott argues that as long as the process is rigorous and offers financial gains to the producers, shade growing does benefit the environment
Natural Choice
Coffee and chocolate
What's the connection between your morning coffee, wintering North American birds and the cool shade of a tree? Actually, quite a lot, says Simon Birch.
When scientists from London's Natural History Museum descended on the coffee farms of the tiny Central American republic of El Salvador, they were astonished to find such diversity of insect and plant species. During 18 months' work on 12 farms, they found a third more species of parasitic wasp than are known to exist in the whole country of Costa Rica. They described four new species and are aware of a fifth. On 24 farms they found nearly 300 species of tree - when they had expected to find about 100.
El Salvador has lost much of its natural forest, with coffee farms covering nearly 10% of the country. Most of them use the 'shade-grown' method of production, which utilises a semi-natural forest ecosystem. Alex Munro, the museum's botanist on the expedition, says: 'Our findings amazed our insect specialist. There's a very sophisticated food web present. The wasps, for instance, may depend on specific species of tree.'
It's the same the world over. Species diversity is much higher where coffee is grown in shade conditions. In addition, coffee (and chocolate) is usually grown in tropical rainforest regions that are biodiversity hotspots. 'These habitats support up to 70% of the planet's plant and animal species, and so the production methods of cocoa and coffee can have a hugely significant impact,' explains Dr Paul Donald of the Royal Society for the Protection of Birds.
So what does 'shade-grown' mean, and why is it good for wildlife? Most of the world's coffee is produced by poor farmers in the developing world. Traditionally they have grown coffee (and cocoa) under the shade of selectively thinned tracts of rain forest in a genuinely sustainable form of farming. Leaf fall from the canopy provides a supply of nutrients and acts as a mulch that suppresses weeds. The insects that live in the canopy pollinate the cocoa and coffee and prey on pests. The trees also provide farmers with fruit and wood for fuel.
'Bird diversity in shade-grown coffee plantations rivals that found in natural forests in the same region,' says Robert Rice from the Smithsonian Migratory Bird Center. In Ghana, West Africa, - one of the world's biggest producers of cocoa - 90% of the cocoa is grown under shade, and these forest plantations are a vital habitat for wintering European migrant birds. In the same way, the coffee forests of Central and South America are a refuge for wintering North American migrants.
More recently, a combination of the collapse in the world market for coffee and cocoa and a drive to increase yields by producer countries has led to huge swathes of shade-grown coffee and cocoa being cleared to make way for a highly intensive, monoculture pattern of production known as 'full sun'. But this system not only reduces the diversity of flora and fauna, it also requires huge amounts of pesticides and fertilisers. In Cote d'Ivoire, which produces more than half the world's cocoa, more than a third of the crop is now grown in full-sun conditions.
The loggers have been busy in the Americas too, where nearly 70% of all Colombian coffee is now produced using full-sun production. One study carried out in Colombia and Mexico found that, compared with shade coffee, full-sun plantations have 95% fewer species of birds.
In El Salvador, Alex Munro says shade-coffee farms have a cultural as well as ecological significance and people are not happy to see them go. But the financial pressures are great, and few of these coffee farms make much money. 'One farm we studied, a cooperative of 100 families, made just $10,000 a year - $100 per family - and that's not taking labour costs into account.'
The loss of shade-coffee forests has so alarmed a number of North American wildlife organisations that they're now harnessing consumer power to help save these threatened habitats. They are promoting a 'certification' system that can indicate to consumers that the beans have been grown on shade plantations. Bird-friendly coffee, for instance, is marketed by the Smithsonian Migratory Bird Center. The idea is that the small extra cost is passed directly on to the coffee farmers as a financial incentive to maintain their shade-coffee farms.
Not all conservationists agree with such measures, however. Some say certification could be leading to the loss - not preservation - of natural forests. John Rappole of the Smithsonian Conservation and Research Center, for example, argues that shade-grown marketing provides 'an incentive to convert existing areas of primary forest that are too remote or steep to be converted profitably to other forms of cultivation into shade-coffee plantations'.
Other conservationists, such as Stacey Philpott and colleagues, argue the case for shade coffee. But there are different types of shade growing. Those used by subsistence farmers are virtually identical to natural forest (and have a corresponding diversity), while systems that use coffee plants as the understorey and cacao or citrus trees as the overstorey may be no more diverse than full-sun farms. Certification procedures need to distinguish between the two, and Ms Philpott argues that as long as the process is rigorous and offers financial gains to the producers, shade growing does benefit the environment
Reading 6
Painters of Time
'The world's fascination with the mystique of Australian Aboriginal art.'
Emmanuel de Roux
Paragraph A
The works of Aboriginal artists are now much in demand throughout the world, and not just in Australia, where they are already fully recognised: the National Museum of Australia, which opened in Canberra in 2001, designated 40% of its exhibition space to works by Aborigines. In Europe their art is being exhibited at a museum in Lyon, France, while the future Quai Branly museum in Paris - which will be devoted to arts and civilisations of Africa, Asia, Oceania and the Americas - plans to commission frescoes by artists from Australia.
Paragraph B
Their artistic movement began about 30 years ago, but its roots go back to time immemorial. All the works refer to the founding myth of the Aboriginal culture, 'the Dreaming'. That internal geography, which is rendered with a brush and colours, is also the expression of the Aborigines' long quest to regain the land which was stolen from them when Europeans arrived in the nineteenth century. 'Painting is nothing without history,' says one such artist, Michael Nelson Tjakamarra.
Paragraph C
There are now fewer than 400,000 Aborigines living in Australia. They have been swamped by the country's 17.5 million immigrants. These original 'natives' have been living in Australia for 50,000 years, but they were undoubtedly maltreated by the newcomers. Driven back to the most barren lands or crammed into slums on the outskirts of cities, the Aborigines were subjected to a policy of 'assimilation', which involved kidnapping children to make them better 'integrated' into European society, and herding the nomadic Aborigines by force into settled communities.
Paragraph D
It was in one such community, Papunya, near Alice Springs, in the central desert, that Aboriginal painting first came into its own. In 1971, a white schoolteacher, Geoffrey Bardon, suggested to a group of Aborigines that they should decorate the school walls with ritual motifs, so as to pass on to the younger generation the myths that were starting to fade from their collective memory. He gave them brushes, colours and surfaces to paint on - cardboard and canvases. He was astounded by the result. But their art did not come like a bolt from the blue: for thousands of years Aborigines had been 'painting' on the ground using sands of different colours, and on rock faces. They had also been decorating their bodies for ceremonial purposes. So there existed a formal vocabulary.
Paragraph E
This had already been noted by Europeans. In the early twentieth century, Aboriginal communities brought together by missionaries in northern Australia had been encouraged to reproduce on tree bark the motifs found on rock faces. Artists turned out a steady stream of works, supported by the churches, which helped to sell them to the public, and between 1950 and 1960 Aboriginal paintings began to reach overseas museums. Painting on bark persisted in the north, whereas the communities in the central desert increasingly used acrylic paint, and elsewhere in Western Australia women explored the possibilities of wax painting and dyeing processes, known as 'batik'.
Paragraph F
What Aborigines depict are always elements of the Dreaming, the collective history that each community is both part of and guardian of. The Dreaming is the story of their origins, of their 'Great Ancestors', who passed on their knowledge, their art and their skills (hunting, medicine, painting, music and dance) to man. 'The Dreaming is not synonymous with the moment when the world was created,' says Stephane Jacob, one of the organisers of the Lyon exhibition. 'For Aborigines, that moment has never ceased to exist. It is perpetuated by the cycle of the seasons and the religious ceremonies which the Aborigines organise. Indeed the aim of those ceremonies is also to ensure the permanence of that golden age. The central function of Aboriginal painting, even in its contemporary manifestations, is to guarantee the survival of this world. The Dreaming is both past, present and future.'
Paragraph G
Each work is created individually, with a form peculiar to each artist, but it is created within and on behalf of a community who must approve it. An artist cannot use a 'dream' that does not belong to his or her community, since each community is the owner of its dreams, just as it is anchored to a territory marked out by its ancestors, so each painting can be interpreted as a kind of spiritual road map for that community.
Paragraph H
Nowadays, each community is organised as a cooperative and draws on the services of an art adviser, a government-employed agent who provides the artists with materials, deals with galleries and museums and redistributes the proceeds from sales among the artists. Today, Aboriginal painting has become a great success. Some works sell for more than $25,000, and exceptional items may fetch as much as $180,000 in Australia.
Paragraph I
'By exporting their paintings as though they were surfaces of their territory, by accompanying them to the temples of western art, the Aborigines have redrawn the map of their country, into whose depths they were exiled,' says Yves Le Fur, of the Quai Branly museum. 'Masterpieces have been created. Their undeniable power prompts a dialogue that has proved all too rare in the history of contacts between the two cultures'
Painters of Time
'The world's fascination with the mystique of Australian Aboriginal art.'
Emmanuel de Roux
Paragraph A
The works of Aboriginal artists are now much in demand throughout the world, and not just in Australia, where they are already fully recognised: the National Museum of Australia, which opened in Canberra in 2001, designated 40% of its exhibition space to works by Aborigines. In Europe their art is being exhibited at a museum in Lyon, France, while the future Quai Branly museum in Paris - which will be devoted to arts and civilisations of Africa, Asia, Oceania and the Americas - plans to commission frescoes by artists from Australia.
Paragraph B
Their artistic movement began about 30 years ago, but its roots go back to time immemorial. All the works refer to the founding myth of the Aboriginal culture, 'the Dreaming'. That internal geography, which is rendered with a brush and colours, is also the expression of the Aborigines' long quest to regain the land which was stolen from them when Europeans arrived in the nineteenth century. 'Painting is nothing without history,' says one such artist, Michael Nelson Tjakamarra.
Paragraph C
There are now fewer than 400,000 Aborigines living in Australia. They have been swamped by the country's 17.5 million immigrants. These original 'natives' have been living in Australia for 50,000 years, but they were undoubtedly maltreated by the newcomers. Driven back to the most barren lands or crammed into slums on the outskirts of cities, the Aborigines were subjected to a policy of 'assimilation', which involved kidnapping children to make them better 'integrated' into European society, and herding the nomadic Aborigines by force into settled communities.
Paragraph D
It was in one such community, Papunya, near Alice Springs, in the central desert, that Aboriginal painting first came into its own. In 1971, a white schoolteacher, Geoffrey Bardon, suggested to a group of Aborigines that they should decorate the school walls with ritual motifs, so as to pass on to the younger generation the myths that were starting to fade from their collective memory. He gave them brushes, colours and surfaces to paint on - cardboard and canvases. He was astounded by the result. But their art did not come like a bolt from the blue: for thousands of years Aborigines had been 'painting' on the ground using sands of different colours, and on rock faces. They had also been decorating their bodies for ceremonial purposes. So there existed a formal vocabulary.
Paragraph E
This had already been noted by Europeans. In the early twentieth century, Aboriginal communities brought together by missionaries in northern Australia had been encouraged to reproduce on tree bark the motifs found on rock faces. Artists turned out a steady stream of works, supported by the churches, which helped to sell them to the public, and between 1950 and 1960 Aboriginal paintings began to reach overseas museums. Painting on bark persisted in the north, whereas the communities in the central desert increasingly used acrylic paint, and elsewhere in Western Australia women explored the possibilities of wax painting and dyeing processes, known as 'batik'.
Paragraph F
What Aborigines depict are always elements of the Dreaming, the collective history that each community is both part of and guardian of. The Dreaming is the story of their origins, of their 'Great Ancestors', who passed on their knowledge, their art and their skills (hunting, medicine, painting, music and dance) to man. 'The Dreaming is not synonymous with the moment when the world was created,' says Stephane Jacob, one of the organisers of the Lyon exhibition. 'For Aborigines, that moment has never ceased to exist. It is perpetuated by the cycle of the seasons and the religious ceremonies which the Aborigines organise. Indeed the aim of those ceremonies is also to ensure the permanence of that golden age. The central function of Aboriginal painting, even in its contemporary manifestations, is to guarantee the survival of this world. The Dreaming is both past, present and future.'
Paragraph G
Each work is created individually, with a form peculiar to each artist, but it is created within and on behalf of a community who must approve it. An artist cannot use a 'dream' that does not belong to his or her community, since each community is the owner of its dreams, just as it is anchored to a territory marked out by its ancestors, so each painting can be interpreted as a kind of spiritual road map for that community.
Paragraph H
Nowadays, each community is organised as a cooperative and draws on the services of an art adviser, a government-employed agent who provides the artists with materials, deals with galleries and museums and redistributes the proceeds from sales among the artists. Today, Aboriginal painting has become a great success. Some works sell for more than $25,000, and exceptional items may fetch as much as $180,000 in Australia.
Paragraph I
'By exporting their paintings as though they were surfaces of their territory, by accompanying them to the temples of western art, the Aborigines have redrawn the map of their country, into whose depths they were exiled,' says Yves Le Fur, of the Quai Branly museum. 'Masterpieces have been created. Their undeniable power prompts a dialogue that has proved all too rare in the history of contacts between the two cultures'