IELTS Academic Reading Practice Test 473

For at least a millennium, pastoralists on the steppes of Central Asia have inhabited a portable dwelling that can be dismantled, transported on pack animals and re-erected within a couple of hours. In Mongolia this structure is known as a ger; foreigners generally employ the Turkish term yurt. Its design has altered remarkably little over the centuries, because it answers two problems at once. The Mongolian plateau swings from summer heat to winter temperatures far below freezing, and the pasture on which livestock depend is exhausted within weeks, obliging families to move several times a year. A ger is therefore light, robust and rapid to assemble.

The circular wall consists of a lattice: a sequence of flat wooden slats lashed together so that they fold shut like a concertina or open into a rigid grid. A substantial ger may incorporate five or six sections, bound to one another with rope manufactured from camel hair or horsehair, enclosing a ring approximately five metres in diameter. The open grid confers a degree of springiness upon the wall, allowing it to flex in powerful winds rather than fracture. Individual sections are light enough for a single person to carry, and the entire timber frame can be loaded onto a lorry or a pair of camels.

Above the wall, long roof poles — rafters — incline inwards from the uppermost edge of the lattice to a wooden ring positioned at the centre of the roof. This ring, termed the crown, constitutes the most significant structural element of the whole assembly: it secures the upper extremities of every rafter and determines the profile of the roof. It simultaneously functions as a chimney and a window, permitting smoke from the stove to escape and daylight to penetrate. In a large ger, two painted pillars stand beneath the crown to bear its weight. The aperture also operates as a sundial, since the patch of sunlight admitted by it traverses the floor throughout the day.

The frame is subsequently covered. Thick sheets of felt, manufactured by wetting and compressing sheep's wool, are wrapped around the lattice and laid across the rafters. Above them is placed a white canvas cover, which repels rain and snow. During winter additional layers of felt are inserted and the lower edge is banked with earth or snow; in summer certain covers are raised to allow air to circulate. Ropes pass entirely around the structure and are drawn tight. A ger is thus held in position by its own weight rather than anchored to the ground.

Felt is among the oldest of textiles, and its manufacture requires no loom. Fleeces are spread in layers, moistened, and then rolled tightly and pressed repeatedly, so that the barbed fibres of the wool interlock into a dense, seamless sheet. The work is exhausting but can be performed by several people together, and it produces a material that insulates far better than woven cloth of comparable weight.

The door frame faces south, away from the prevailing winter wind, and normally incorporates a solid wooden door, occasionally richly decorated. Within, the interior is organised according to strict conventions. The northern side, opposite the entrance, constitutes the place of honour, where visitors are seated and the family's most treasured possessions are displayed. The stove occupies the centre, directly beneath the crown, and the floor is covered with carpets or felt. Traditionally, men occupied the western half and women the eastern, and a guest who seated themselves in the incorrect position would be quietly corrected.

Erecting a ger is a skill acquired in childhood. An experienced family can assemble one in roughly an hour and dismantle it more rapidly still; at festivals where teams compete, the swiftest accomplish the task in a fraction of that period. The wooden components — lattice slats, rafters and crown — are normally produced by specialist carpenters, whereas the felt is the work of the herders themselves. A well-constructed frame may endure for decades, repaired piece by piece as individual parts deteriorate.

The craft received international recognition in 2013, when UNESCO inscribed the traditional craftsmanship of the Mongolian ger, together with its associated customs, on its representative list of intangible cultural heritage. The inscription encompasses not merely the carpentry and the felt-making but the elaborate etiquette surrounding the dwelling: how to approach it, where to sit, and how to offer and accept food. For Mongolians the ger remains a potent emblem of national identity, and families who have relocated to apartments frequently retain one for summer occupation.

The majority of Mongolians now reside in towns, and a substantial proportion of the capital, Ulaanbaatar, inhabits districts of gers and rudimentary houses encircling the city. Here the dwelling has acquired difficulties for which it was never intended. In a valley where winter air is trapped by temperature inversions, the stoves that heat gers contribute substantially to atmospheric pollution, and piped water and sewerage are absent from many plots. Aid organisations have distributed improved stoves, and municipal authorities have attempted to persuade residents to relocate into apartments, although many prefer to remain. A ger is accompanied by land that may eventually be developed.

Yet the ger survives because it suits a mode of existence that has not vanished. Herders continue to spend the summer in transit, and a dwelling that can be dismantled, loaded and reconstructed within a morning remains the most practical solution to that exigency. Engineers concerned with disaster relief have also displayed interest, since a structure requiring neither foundations nor machinery for its assembly has evident applications following an earthquake.

Humans spend roughly a third of their lives asleep, and for part of that time the brain produces experiences so vivid that they are sometimes mistaken for reality on waking. Dreams can be mundane or terrifying, coherent or nonsensical, and they have been explained in many ways: as messages from the gods, as prophecies, as the wanderings of the soul and, in the twentieth century, as the disguised expression of forbidden wishes. Only since the 1950s has it been possible to watch a sleeping brain at work, and much of what has been learned since then has made dreaming more puzzling rather than less.

The modern study of dreams began with a discovery about sleep itself. In 1953, Eugene Aserinsky, a graduate student at the University of Chicago working with the physiologist Nathaniel Kleitman, noticed that sleeping infants occasionally moved their eyes rapidly beneath closed lids. When the researchers recorded the electrical activity of the brain in adults during these periods, they found a pattern that closely resembled the waking state: fast, low-voltage waves, quite different from the slow, high-amplitude waves of deep sleep. The stage was named rapid eye movement sleep, or REM, and volunteers woken from it almost always reported a dream.

REM sleep is strange in other ways. The muscles of the body are effectively paralysed, apart from the eyes and the muscles used in breathing, so the dreamer cannot act out what is happening. Meanwhile the heart rate and breathing become irregular, and the brain consumes about as much energy as it does when awake. Sleep is not one uniform state but a cycle: periods of REM recur roughly every ninety minutes, becoming longer towards morning, and in total they occupy about a fifth of an adult's night. REM is not the only source of dreams, however, since sleepers woken from other stages also report them, though usually shorter and more like ordinary thought. Reports gathered in this way are inevitably fragmentary, because the sleeper must be woken in order to describe what has just passed through the mind.

Because dreams are difficult to capture, theories have to be built from indirect evidence. In 1977 two psychiatrists, John Allan Hobson and Robert McCarley, proposed that REM sleep is generated by bursts of random electrical activity in the brainstem, the stalk of tissue at the base of the brain. On this account the cortex, which is specialised for making sense of information, does its best with what it receives, weaving a story out of meaningless signals. Hobson maintained that dreams therefore have no function at all: they are a by-product of the sleeping brain, like the noise made by a machine. Critics objected that the theory left no room for meaning, and later work showed that the cortex is far from passive during sleep.

The strongest challenge to that view has come from research on memory. Sleep is now known to consolidate memory: fragile new memories are transferred into more lasting storage, and this happens largely while we are asleep. Recordings made in the 1990s from rats' brains showed that the sequence of activity produced while an animal runs a maze is repeated during sleep, suggesting that the brain is rehearsing what it has learned. In humans, the hippocampus, a structure deep in the temporal lobe, is central to this process.

Other theories focus on content rather than mechanism. In 2000 the Finnish psychologist Antti Revonsuo put forward the threat simulation hypothesis, which holds that dreams provide a safe arena in which to rehearse danger and practise responses to it, an ability that would have been useful to our ancestors. A different view, the continuity hypothesis, is associated with the American researcher William Domhoff, who has argued that dreams simply reflect the emotional concerns of waking life. Each theory accounts for some observations and struggles with others: many dreams, for instance, contain no threat at all, and content analysis suggests that dreams are usually duller and more ordinary than dreamers remember.

One phenomenon has begun to yield to experiment. In lucid dreams the sleeper knows that they are dreaming, and in the 1980s researchers showed that such dreamers could signal to the laboratory by moving their eyes in an agreed pattern, allowing the content of a dream to be reported while it was happening. Lucid dreaming is uncommon in the general population, though it can be learned to some extent. Clinicians have begun to use it as a treatment, teaching people who suffer from frequent nightmares to recognise the dream and change its course, and early trials with patients affected by post-traumatic stress have produced encouraging results.

Many basic questions remain. Almost everyone dreams, but people differ enormously in how much they remember: some recall several dreams a week and others none, and it is not clear whether the difference lies in the dreams or in the memory of them. Dreams fade within minutes of waking, particularly if the sleeper shifts position or is disturbed. Studies of people who claim never to dream have found that they usually report detailed dreams when woken directly from REM. As for the oldest question of all, the function of dreaming remains unresolved; it may be that dreams serve several purposes at once, or that they are the price the brain pays for other processes that occur around them. Whether other animals dream in anything like the human sense is also undecided.

Fireworks have marked public celebrations for centuries, and in many countries private use is concentrated in a single night of the year: 31 December in much of Europe, 4 July in the United States, Diwali in India and the Lunar New Year across East Asia. Supporters describe the custom as communal art, cheap enough for everyone to join in and visible from any rooftop. Yet a growing number of cities have restricted or banned the sale of fireworks to individuals, and it is worth asking what the evidence behind those restrictions actually shows.

The most consistent objection concerns air quality. A firework is, in effect, a small chemical reactor: a charge carries it upwards, and a mixture of oxidisers, fuels and metal salts burns to produce light and colour. Strontium compounds give red, barium green and copper blue. The particles left behind after the display are fine enough to be drawn deep into the lungs, and monitoring stations in European and North American cities have repeatedly recorded sharp rises in concentrations of fine particulate matter in the hours after midnight, sometimes many times the normal level, before falling again within a day. The metals that colour the display are deposited on streets, roofs and water, and the cases themselves must be swept up the next morning.

Noise is the complaint that residents make most often. Close to a large device, sound levels can exceed 140 decibels, a level at which hearing can be damaged, although the risk to spectators at a well-organised public display is small. Because sound spreads in all directions and carries over rooftops, a private display in a garden is heard by hundreds of households that have no part in it. The noise is brief, but it is unpredictable, and unpredictability is what makes it hard to tolerate.

Some residents suffer more than others. People with post-traumatic stress disorder report that an unexpected explosion can bring back the symptoms of their condition, and autistic people and others with sensory sensitivities often find an unscheduled bang far harder to manage than a display they know about in advance. Shift workers who must sleep during the day, parents of small babies and frail elderly people are also regularly heard from in city consultations. What these groups have in common is not that the noise is loud but that they have no way of knowing when it will come, and no realistic means of escaping it.

Animals are affected in ways that researchers have documented with some care. A study of geese in the Netherlands, using tracking devices, found that the birds took flight at midnight on 31 December and stayed unusually high and active for several days, apparently because the disturbance drained energy they could not spare in winter. Wild birds roosting in city centres are flushed from their perches in the same way. Dogs are frightened too, and charities advise owners to keep animals indoors, to close the curtains and to provide a familiar place to hide. Farmers report injured livestock that have bolted through fences in panic.

Fireworks injure people as well. Emergency departments treat burns, blast injuries to the hands and face and injuries to the eye, and the patients are disproportionately young men and boys; most of these injuries come from devices bought legally and set off by amateurs in gardens or streets. Fires are another cost, since dry grass, balconies, hedges and, in some cities, historic timber buildings have been set alight by falling sparks. Fire and rescue services therefore argue for tighter rules, and they note that their busiest night of the year is entirely predictable. What they cannot do is enforce a ban. Police are thinly stretched on 31 December, and a law that is widely broken makes other rules harder to uphold.

Opponents of prohibition make several arguments. Some see a ban as an intrusion on personal liberty that is out of proportion to the harm, since other accepted activities, from wood-burning stoves to motor racing, carry comparable risks. Others defend the tradition: a festival without fireworks, they say, is diminished, and replacing private fireworks with ticketed displays turns an event that anyone could join into one that costs money and excludes the poorest. There is a practical objection as well, and it has been borne out in cities that have tried prohibition: a ban on sales does not end use but pushes it into an unregulated market, in which devices are more powerful, less safe and untaxed.

The evidence, in my view, supports neither an outright ban nor the status quo. The harms described above are real, but they are concentrated in a few hours of the year, and a blanket prohibition is a blunt instrument that falls hardest on those who can afford it least. What is defensible is targeted regulation: sales restricted to licensed shops in the days before major festivals, strict noise limits on the largest devices, quiet zones around hospitals and care homes, and public money for organised displays, which concentrate both noise and pollution into a short, supervised event that residents can plan around. A city that bans private fireworks usually loses control of them; a city that regulates them does not.