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What is the main idea of the (last three paragraphs)？
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Since about 1950, public transportation in the U.S. has had to struggle to survive. The growth of private automobile ownership, the change in cities with accelerated urban sprawl, and the immense highway construction program have added to transit problems. Moreover, changes in life-style. have contributed to reduced transit use, which has resulted in lower revenues from fares at a time when costs for operations have increased greatly.
As private transit systems were taken over by local government and the cost of operations continued to increase, pressure was exerted for federal participation in urban public transportation. The 1964 Urban Mass Transportation Act established this commitment. The legislation limited federal assistance to g0 percent of the capital expenditure for buses, rail cars, and fixed facilities. In 1974 the federal government added operating assistance to its program. Because passenger fares account for only about one-third of the average system' s operating funds, demand for federal subsidies escalated rapidly. In the early 1980s a Change in federal transportation policy resulted in relaxation of the rigid standards governing the way federal aid is used, imposing requirements for private sector participation and increased state, regional, and local funding. By the
end of the 1980s state and local operating assistance amounted to about 2 percent of the funds needed to operate U.S. transit systems; fare box and other revenues accounted for 43 percent, and federal assistance, 5 percent.
Private sector initiatives in public transportation include transit services provided by private operators under competitively bid contracts, and innovative public-private projects such as a joint development of transit stations.
It is estimated that 8 million people in the U.S. (5 percent of the urban population) have physical handicaps that prevent them from using conventional transportation services. With the aging of the population, more than one-fifth 0fthe people living in the U.S. will be over 65 in the year 2030. Many of the people in these groups are dependent on public transportation. In 1990 Congress passed the Americans with Disabilities Act, which will virtually require all transit services to be accessible to the disabled.
In the short run, existing transit modes will be improved. Cities with such systems will extend their lines, while others will plan and construct new ones, including rapid transit, buses, and light rail transit. The lower-cost alternatives will have a better chance of adoption. There is also a strong interest in commuter rail. Part of the appeal of this mode of transportation is that many cities have unused and underused rail corridors that can provide rights-of-way at low cost.
Because of major environmental concerns, electric trolley buses and methanol-powered and other alter- native fuel-powered buses will replace diesel engine buses.
An enormous range of new technology exists in the area of intelligent vehicle systems. For example, a commuter will be able to get real-time information on home computers as to when the next bus will arrive at the nearest bus stop. Information for trip planning will be available as well. Transit agencies will use advanced technologies for traffic and fleet management of their vehicles. Vehicle control systems that will guide buses along prescribed corridors and routes are being researched to reduce vehicle delay, increase capacity, and improve safety.
Automation through new technology can provide a means for reducing labor while providing performance and safety. A number of automated guideway transit systems operate in airports, shopping centers, college campuses, and amusement parks. Their applicability to a more diverse use is continually evaluated. Research is under way on magnetically levitated and air-supported vehicles. Directional control, spacing, switching, and lateral control are among
Which of the following situations is among the troubles print has？
From this passage, we can conclude that______.
Researchers investigating brain size and mental ability say their work offers evidence that education protects the mind from the brain's physical deterioration.
It is known that the brain shrinks as the body ages, but the effects on mental ability are different from person to person. Interestingly, in a study of elderly men and women, those who had more education actually had more brain shrinkage.
"That may seem like bad news," said study author Dr. Edward Coffey, a professor of psychiatry and of neurology at Henry Ford Health System in Detroit. However, he explained, the finding suggests that education allows people to withstand more brain-tissue loss before their mental functioning begins to break down..
The study, published in the July issue of Neurology, is the first to provide biological evidence to support a concept called the "reserve" hypothesis, according to the researchers. In recent years, investigators have developed the idea that people who are more educated have greater cognitive reserves to draw upon as the brain tissue to spare.
Examining brain scans of 320 healthy men and women ages 66 to 90, researchers found that for each year of education the subjects had, there was greater shrinkage of the outer layer of the brain known as the cortex. Yet on tests of cognition and memory, all participants scored in the range indicating normal.
"Everyone has some degree of brain shrinkage," Coffey said. "People lose (on average) 2.5 percent per decade starting at adulthood."
There is, however, a "remarkable range" of shrinkage among people who show no signs no mental decline, Coffey noted. Overall health, he said, accounts for some differences in brain size. Alcohol or drug use, as well as medical conditions such as diabetes and high blood pressure, contribute to brain-tissue loss throughout adulthood.
In the absence of such medical conditions, Coffey said, education level helps explain the range of brain shrinkage exhibited among the mentally-fit elderly. The more-educated can withstand greater loss.
Coffey and colleagues gauged shrinkage of the cortex by measuring the cerehrospinal fluid surrounding the brain. The greater the amount of fluid, the greater the cortical shrinkage.
Controlling for the health factors that contribute to brain injury, the researchers found that education was related to the severity of brain shrinkage. For each year of education from first grade on, subjects had an average of 1.77 milliliters more cerebrospinal fluid around the brain.
For example, Coffey's team reported, among subjects of the same sex and similar age and skull size, those with 16 years of education had 8 percent to 10 percent more cerebrospinal fluid compared with those who had four years of schooling.
Of course, achieving a particular education level is not the definitive measure of someone's mental capacity. And, said Coffey, education can be "a proxy for many things". More-educated people, he noted, are often less likely to have habits, such as smoking, that harm overall health.
But Coffey said that his team's findings suggest that like the body, the brain benefits from exercise. "The question is whether by continuing to exercise the brain we can forestall the effects of (brain shrinkage)," he said. "My hunch is that we can."
According to Coffey, people should strive throughout life to keep their brains alert by exposing them- selves to new experiences. Travelling is one way to stimulate the brain, he said; a less adventuresome way is to do crossword puzzles.
"A hot topic down the road," Coffey said, will be whether education even late in life has a protective effect against mental decline.
Just how education might affect brain cells is unknown. In their report, the researchers speculated that in people with more education, certain brain structures deeper than the cortex may stay intact to comp
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