READING PASSAGE 1
You should spend about 20 minutes on Questions 1-13, which are based on Reading Passage 1 below.
The Diagnose of Bridge
A. MOST road and rail bridges are only inspected visually, if at all. Every few months, engineers have to clamber over the structure in an attempt to find problems before the bridge shows obvious signs of damage. Technologies developed at Los Alamos National Laboratory, New Mexico, and Texas A&M University may replace these surveys with microwave sensors that constantly monitor the condition of bridges.
B. “The device uses microwaves to measure the distance between the sensor and the bridge, much like radar does,” says Albert Migliori, a Los Alamos physicist. “Any load on the bridge- such as traffic- induces displacements, which change that distance as the bridge moves up and down.” By monitoring these movements over several minutes, the researchers can find out how the bridge resonates. Changes in its behavior can give an early warning of damage.
C. The Interstate 40 bridge over the Rio Grande river in Albuquerque provided the researchers with a rare opportunity to test their ideas. Chuck Farrar, an engineer at Los Alamos, explains: “The New Mexico authorities decided to raze this bridge and replace it. We were able to mount instruments on it, test it under various load conditions and even inflict damage just before it was demolished. “In the 1960s and 1970s, 2500 similar bridges were built in the US. They have two steel girders supporting the load in each section. Highway experts know that this design is “fracture critical” because a failure in either girder would cause the bridge to fail.
D. After setting up the microwave dish on the ground below the bridge, the Los Alamos team installed conventional accelerometer at several points along across it and while subjecting it to pounding from a “shaker”, which delivered precise punches to a specific point on the road.
E. “We then created damage that we hoped would simulate fatigue cracks that can occur in steel girders,” says Farrar. They first cut a slot about 60 centimeters long in the middle of one girder. They then extended the cut until it reached the bottom of the girder and finally they cut across the flange- the bottom of the girder’s “I” shape.
F. The initial, crude analysis of the bridge’s behavior, based on the frequency at which the bridge resonates, did not indicate that anything was wrong until the flange was damaged. But later the data were reanalyzed with algorithms that took into account changes in the mode shapes of the structure- shapes that the structure takes on when excited at a particular frequency. These more sophisticated algorithms, which were developed by Norris Stubbs at Texas A&M University, successfully identified and located the damage caused by the initial cut.
G. “When any structure vibrates, the energy is distributed throughout with some points not moving, while others vibrate strongly at various frequencies,” says Stubbs. “My algorithms use pattern recognition to detect changes in the distribution of this energy.” NASA already uses Stubbs’ method to check the behavior of the body flap that slows space shuttles down after they land.
H. A commercial system based on the Los Alamos hardware is now available, complete with the Stubbs algorithms, from the Quatro Corporation in Albuquerque for about $100 000.
I. Tim Darling, another Los Alamos physicist working on the microwave interferometer with Migliori, says that as the electronics become cheaper, a microwave inspection system will eventually be applied to most large bridges in the US. “In a decade I would like to see a battery or solar-powered package mounted under ea bridge, scanning it every day to detect changes,” he says.
READING PASSAGE 2
You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 below.
Western Immigration of Canada
A. By mid-1870s Canada wanted an immigrant population of agricultural settlers established in the West. No urban centres existed on the prairies in the 1870s, and rural settlement was the focus of the federal government’s attention. Western rural settlement was desired, as it would provide homesteads for the sons and daughters of eastern farmers, as eastern agricultural landfilled to capacity. As well, eastern farmers and politicians viewed western Canada, with its broad expanses of unpopulated land, as a prime location for expanding Canada’s agricultural output, especially in terms of wheat production to serve the markets of eastern Canada.
B. To bolster Canada’s population and agricultural output, the federal government took steps to secure western land. The Dominion of Canada purchased Rupert’s Land from the Hudson’s Bay Company in 1870. In 1872, the federal government enacted the Dominion Lands Act. This act enabled settlers to acquire 160 acres of free land, as long as settlers remained on their land for a period of three years, made certain minor improvements to the land, and paid a $10.000 registration fee. The Canadian government also created a Mounted Police Force in 1873. The Mounties journeyed West to secure the area for future settlers. By 1876 the NWMP had established themselves in the West. The major posts included Swan River, Fort Saskatchewan, Fort Calgary, Fort Walsh and Fort Macleod. All of these initiatives attracted a number of eastern- Canadian settlers, as well as European and American immigrants, to Canada’s West, and particularly to the area of Manitoba.
C. The surest way to protect Canadian territory, and to achieve the secondary goal of joining British Columbia to the rest of the country, was to import large numbers of Eastern Canadian and British settlers. Settling the West also made imperative the building of a transcontinental railway. The railway would work to create an east-west economy, in which western Canada would feed the growing urban industrial population of the east, and in return become a market for eastern Canadian manufactured goods.
D. Winnipeg became the metropolis of the West during this period. Winnipeg’s growth before 1900 was the result of a combination of land speculation, growth of housing starts, and the federal government's solution in 1881 of Winnipeg as a major stop along the CPR. This decision culminated in a land boom between 1881 and 1883 which resulted in the transformation of hamlets like Portage la Prairie and Brandon into towns. And a large increase in Manitoba’s population. Soon, Winnipeg stood at the junction of three transcontinental railway lines which employed thousands in rail yards. Winnipeg also became the major processor of agricultural products for the surrounding hinterland.
E. The majority of settlers to Winnipeg, and the surrounding countryside, during this early period, were primarily Protestant English-speaking settlers from Ontario and the British Isles. These settlers established Winnipeg upon a Britsh-Ontaian ethos which came to dominate the society’s social, political, and economic spirit. This British-Ontarian ethnic homogeneity, however, did not last very long. Increasing numbers of foreign immigrants, especially from Austria-Hungary and Ukraine soon added a new ethic element to the recent British, the older First Nation Metis, and Selkirk’s settler population base. Settling the West with (in particular) Eastern Canadians and British immigrant offered the advantage of safeguarding the 49th parallel from the threat of American take-over, had not the Minnesota legislature passed a resolution which provided for the annexation of the Red River district. The Red River in 1870 was the most important settlement on the Candian prairies. It contained 11,963 inhabitants of whom 9,700 were Metis and 575 First Nations. But neighbouring Minnesota already had a population of over 100,000.
F. Not all of the settlers who came to western Canada in the 1880s, however, desired to remain there. In the 1870s and 1880s, economic depression kept the value of Canada’s staple exports low, which discouraged many from permanent settlement in the West. Countries including Brazil, Argentina, Australia, New Zealand and the United States competed with Canada for immigrants. Many immigrants, and thousands of Canadians, chose to settle in the accessible and attractive American frontier. Canada before 1891 has been called “a huge demographic railway station” where thousands of men, women, and children were constantly going and coming, and where the number of departures invariably exceeded that of arrivals.
G. By 1891 Eastern Canada had its share of both large urban centres and problems associated with city life. While the booming economic centers of Toronto and Montreal were complete with electricity and telephones in the cities’ wealthiest areas by the turn of the century, slum conditions characterized the poorest areas like the district known as ‘the Ward’ in Toronto. Chickens and pigs ran through the streets; privy buckets spilled onto backyards and lanes creating cesspools in urban slums. These same social reformers believed that rural living, in stark contrast to urban, would lead to a healthy, moral, and charitable way of life. Social reformers praised the ability of fresh air, hard work, and open spaces for ‘Canadianising’ immigrants. Agricultural pursuits were seen as especially fitting for attaining this ‘moral’ and family-oriented way of life, in opposition to the single male-dominated atmosphere of the cities. Certainly, agriculture played an important part of the Canadian economy in 1891. One-third of the workforce worked on farms.
H. The Canadian government presented Canada’s attractions to potential overseas migrants in several ways. The government offered free or cheap land to potential agriculturists. As well, the government established agents and/or agencies for the purpose of attracting emigrants overseas. Assited passage schemes, bonuses and commissions to agents an settlers and pamphlets also attracted some immigrants to Canada. The most influential form of attracting others to Canada, however, remained the letters home written by emigrants alrealdy in Canada. Letters from trusted friends and family members. Letters home often contained exggerations of the ‘wonder of the new world.’ Migrant workers and settlers already in Canada did not want to disappoint, or worry, their family and friends at home. Embellished takes of good fortune and happiness often succeeded in encouraging others to come.
READING PASSAGE 3
You should spend about 20 minutes on Questions 27-40, which are based on Reading Passage 3 below.
Talc Powder
A. Peter Brigg discovers how talc from Luzenac’s Trimouns in France finds its way into food and agricultural products – from chewing gum to olive oil. High in the French Pyrenees, some 1,700m above sea level, lies Trimouns, a huge deposit of hydrated magnesium silicate – talc to you and me. Talc from Trimouns, and from ten other Luzenac mines across the globe, is used in the manufacture of a vast array of everyday products extending from paper, paint and plaster to cosmetics, plastics and car tyres. And of course, there is always talc’s best-known end use: talcum powder for babies’ bottoms. But the true versatility of this remarkable mineral is nowhere better displayed than in its sometimes surprising use in certain niche markets in the food and agriculture industries.
B. Take, for example, the chewing gum business. Every year, Talc de Luzenac France- which owns and operates the Trimouns mine and is a member of the international Luzenac Group (art of Rio Tinto minerals)- supplies about 6,000 tones of talc to chewing gum manufactures in Europe. “We’ve been selling to this sector of the market since the 1960s”, says Laurent Fournier, sales manager in Luzenac’s Specialties business unit in Toulouse. “Admittedly, in terms of our total annual sales of talc, the amount we supply to chewing gum manufactures is relatively small, but we see it as a valuable niche market: one where customers place a premium on securing supplies from a reliable, high-quality source. Because of this, long terms allegiance to a proven supplier is very much a feature of this sector of the talc market.” Switching sources- in the way that you might choose to buy, say, paperclips from Supplier A rather than from Supplier B- is not an easy option for chewing gum manufactures,” Fournier says. “The cost of reformulating is high, so when customers are using a talc grade that works, even if it’s expensive, they are understandably reluctant to switch.”
C. But how is talc actually used in the manufacture of chewing gum? Patrick Delord, an engineer with a degree in agronomics, who has been with Luzenac for 22 years and is now senior market development manager, Agriculture and Food in Europe, explains that chewing gums has four main components. “The most important of them is the gum base”, he says. “It’s the gum base that puts the chew into chewing gum. It binds all the ingredients together, creating a soft, smooth texture. To this the manufacturer then adds sweeteners, softeners and flavourings. Our talc is used as a filler in the gum base. The amount varies between, ten and 35 per cent, depending on the type of gum. Fruit flavoured chewing gum, for example, is slightly acidic and would react with the calcium carbonate that the manufacturer might otherwise use as a filler. Talc, on the other hand, makes an ideal filler because it’s non-reactive chemically. In the factory, talc is also used to dust the gum base pellets and to stop the chewing gum sticking during the lamination and packing process,” Delord adds.
D. The chewing gum business is, however, just one example of talc’s use in the food sector. For the past 20 years or so, olive oil processors in Spain have been taking advantage of talc’s unique characteristics to help them boost the amount of oil they extract from crushed olives. According to Patrick Delord, talc is especially useful for treating what he calls “difficult” olives. After the olives are harvested- preferably early in the morning because their taste is better if they are gathered in the cool of the day- they are taken to the processing plant. There they are crushed and then stirred for 30-45 minutes. In the old days, the resulting paste was passed through an olive press but nowadays it’s more common to add water and centrifuge the mixture to separate the water and oil from the solid matter. The oil and water are then allowed to settle so that the olive oil layer can be decanted off and bottled. “Difficult” olives are those that are more reluctant than the norm to yield up their full oil content. This may be attributable to the particular species of olive, or to its water content and the time of year the olives are particular species of olive, or to its water content and the time of year the olives are collected- at the beginning and the end of the season their water content is often either too high or too low. These olives are easy to recognize because they produce a lot of extra foam during the stirring process, a consequence of an excess of a fine solid that acts as a natural emulsifier. The oil in this emulsion is lost when the water is disposed of. Not only that, if the waste water is disposed of directly into local fields- often the case in many smaller processing operations- the emulsified oil may take some time to biodegrade and so be harmful to the environment.
E. “If you add between a half and two per cent of talc by weight during the stirring process, it absorbs the natural emulsifier in the olives and so boosts the amount of oil you can extract,” says Delord. “In addition, talc’s flat, ‘platey’ structure helps increase the size of the oil droplets liberated during stirring, which again improves the yield. However, because talc is chemically inert, it doesn’t affect the colour, taste, appearance or composition of the resulting olive oil.”
F. If the use of talc in olive oil processing and in chewing gum is long established, new applications in the food and agriculture industries are also constantly being sought by Luzenac. One such promising new market is fruit crop protection, being pioneered in the US. Just like people, fruit can get sunburned. In fact, in every sunny region, up to 45 per cent of a typical crop can be affected by heart stress and sunburn. However, in the case of fruit, it’s not so much the ultra violet rays which harm the crop as the high surface temperature that the sun’s rays create.
G. To combat this, farmers normally use either chemicals or spray a continuous fine canopy of mist above the fruit trees or bushes. The trouble is, this uses a lot of water- normally a precious commodity in hot, sunny areas – and it is therefore expensive. What’s more, the ground can quickly become waterlogged. “So our idea was to coat the fruit with talc to protect it from the sun”, says Greg Hunter, a marketing specialist who has been with Luzenac for ten years. “But to do this, several technical challenges had first to be overcome. Talc is very hydrophobic: it doesn’t like water. So in order to have a viable product we needed a wettable powder – something that would go readily into suspension so that it could be sprayed onto the fruit. It also had to break the surface tension of the cutin (the natural waxy, waterproof layer on the fruit) and of course it had to wash off easily when the fruit was harvested. No-one’s going to want an apple that’s covered in talc.”
H. Initial trials in the state of Washington in 2003 showed that when the product was sprayed onto Granny Smith apples, it reduced their surface temperature and lowered the incidence of sunburn by up to 60 per cent. Today the new product, known as Invelop Maximum SPF, is in its second commercial year on the US market. Apple growers are the primary target although Hunter believes grape growers represent another sector with long term potential. He is also hopeful of extending sales to overseas markets such as Australia, South America and southern Europe.
