Good morning. The discussion topic for today's seminar is “Homelessness in America” In the United States homelessness has grown at a dramatic rate during the last decade. Estimates of the number of Americans currently without a permanent home vary wildly. Advocacy groups like the National Coalition for the Homeless say that closeto 3 million Americans live on the streets or in emergency and temporary shelters. The US department concerned puts the figure at 350,000. Yet both bureaucrats and advocates agree on one point, that is, the face of homelessness has changed radically in the past 10 years, as more and more low-income housing is mowed down inthe name of progress. Some 20 years ago, the typical “street person” was a white male who suffered from a mental illness or an addiction to drugs or alcohol. Today's homeless, however, are a more eclectic group. More than 60 percent of the homeless today are Black, mostly single mothers with small children. More than half of them have never been homeless before. In many cases, they have been evicted from their homes, or the low-income housing in which they lived was demolished or burned down. About 60 percent of all homeless people live on some form of public assistance with an average monthly income of 450 dollars. About 20 percent are mentally ill.
All sorts of people have been pushed out of the housing market because of the critical shortage of affordable places to live. As a result, homelessness has climbed to the top of the “me-generation's” short list of social concerns. But there is a great gap between concern and active involvement in the effort to solve this growing problem. For many people, the inaction is due to ignorance, not indifference.
The fact is that there are many ways in which individuals can help the homeless. Yet for those people truly interested in the cause, one of the first steps is to get to know the homeless and understand how they became that way. Many advocates believe that it is important for middle-class people to get to know and reach out to the homeless and bridge the gap that exists.
W: The other day I was reading a book about roofs, and I got very confused. You see, I think I may have some repairs done on my roof, and went to the library and borrow that book on roofs. I was trying to understand the hasic principles of roof construction. You know I have been interested in this kind of stuff ever since my retirement.
M: What's wrong with your roof?
W: The trouble is in what I think they call trusses, spelt T-R-U-S-S-E-S, and that's one of the terms that confuses me.
M: Well, a truss is a structure with straight pieces forming triangles to support a load. When properly designed, these pieces are placed only under tension and compression and do not bend.
W: You mean a truss is a triangle structure that supports a load.
M: That's right.
W: Also in the book I was reading, they talked about rises and spans.
M: Well. the distance between the centers of support is called the span. Rise is the distance between the highestpoint and base of the structure. The top members of the truss are called upper chords, while the base membersare the lower chords. It's really very simple.
W: Well, it may be to you as a builder. It's really too complicated to me. Anyway, I have one more question for you. How much weight must the truss support?
M: First of all, of course, its own weight. Then the roof covering. In addition, depending on the locality. the truss must be able to support the weight of snow and the pressure of wind in severe weather conditions.
W: Aren't trusses used in bridges, too?
M: Sure. Some suspension bridges have very long spans, as long as over 6,500 feet. By the way, the idea of the truss is a very old one. I read somewhere that, even in the Bronze Age, primitive men used trusses in their lake houses.
W: Well, I think I'll be able to understand what I read a little better now. I shall not worry about being overcharged by you builders.
M: You must be kidding. You really shouldn't.
关于房屋结构解释。
03 1603 - News Listening
BAMAKO, MALI
Malians woke up to a state of emergency after Friday's assault on the Radisson Blu Hotel in the capital killed
20 people plus two assailants, according to a military commander.
In addition to an American public health worker murdered in a terrorist raid on a luxury hotel in Mali's capitalon Friday, the 19 dead included six Russians, three Chinese, two Belgians and an Israeli national.
Two gunmen who conducted the assault died after Mali Special Forces entered the hotel. Mali troops, backedby French and U.S. Special Forces, conducted a seven-hour operation Friday that ended the violence and led to therescue of 170 hotel guests and staff held hostage during the siege.
SANTA CRUZ, BRAZIL
A wave of toxic mud travelling down the Rio Doce River in Brazil from a collapsed dam has reached the Atlantic Ocean, amid concerns it will cause severe pollution. The waste has travelled more than 500 km since the dam at an iron mine collapsed two weeks ago. The contaminated mud, tested by the water management authorities, was found to contain toxic substances like mercury, arsenic and chromium at levels exceeding human consumption levels.
In an interview, Andres Ruchi, director of the Marine Biology School in Santa Cruz, said that mud could have a devastating impact on marine life when it reaches the sea. He said the area of sea near the mouth of the Rio Doceis a feeding and breeding location for many species of marine life including the threatened leatherback turtle, dolphins and whales.
TEXAS，UNITED STATES
A security hole that could allow attackers to access users' personal data was inadvertently placed on Dell computers, the company has admitted. The hole represented a “profound security flaw”that could allow access to bank details and other personal data, experts said. Dell has issued guidance on removing the software that produced it.
In a statement released on Monday, Dell acknowledged the vulnerability and linked to a guide on permanently removing the software that caused it. “We became aware that a certificate (eDellRoot), installed on our PCs unintentionally introduced security vulnerability. The certificate was implemented as part of a support tool and intended to make it faster and easier for our customers. Customer security and privacy is a top concern and priority for Dell; we deeply regret that this has happened and are taking steps to address it.”
LEEDS, GREAT BRITAIN
Nearly 60 years ago, a crane was brought in to lift a huge computer “capable of addtion and substraction” into the disused Eidon Chapel across from our Chemistry building. Today, think about all the things the little microchip in your phone can do.
Micro-bubbles will be to drugs and manufacturing what microchips were to computing. In the near future, micro-bubbles will float through the human body to carry a drug to its target. And beyond medicine, you'll see how very small mixtures will revolutionise some manufacturing processes. Then, what's a micro-bubble?
Imagine a soap bubble that's 100th the size of a human hair. It includes a gas core and a surrounding shell. Why would such a small bubble be useful? It already is. Micro-bubbles were developed in the 1990s to improve the clarity of ultrasound. They help measure blood flow in organs because their gas core reflects stronger ultrasound waves better than tissue does. Scientists started thinking, “if these bubbles can safely travel around the human body, let's get a drug to hitch a ride and be dropped off exactly where we want it to go.”
NEW YORK, UNTTED STATES
Disney dragged down the Dow Jones industrial average Friday after the media and entertainment giant said ESPN lost 3 million subscribers in the last year.
Disney fell $3.54.or 3 percent, to $115.13, its biggest one-day loss since August. Late Wednesday, Disney disclosed that U.S. subscribers to its ESPN sports channel fell for the second year in a row, to 92 million as of 0ct.3, matching the lowest total since 2006. ESPN's subscriber totals had hovered around 100 million for years.
Disney has said that ESPN has lost subscribers, but investors appeared shaken by the size of the losses. Small but growing numbers of people are opting out of traditional cable TV bundles and buying smaller, less expensive groups of channels instead. Investors in media companies are worried about potential losses of subscribers and revenue.
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