Unit Testing of Software Essay Example | Topics and Well Written Essays - 1000 words

Unit Testing of Software - Essay Example Unit testing increases confidence in maintaining or changing the code. Good unit tests also increase the detectability of defects that may arise when changing codes. The development of unit testing is faster. The test runs take very less time as there is no need of firing the GUI and providing all the inputs. Â  Additionally, fixing defects detected during unit testing costs lesser than in higher levels of testing (Craig & Jaskiel, 2002). Debugging at this level is easy since only the latest changes need to be debugged contrary to higher levels where changes made over the span of several days or weeks may need to be debugged (Software Testing). Â  There are limits to the number of scenarios and test data that a developer can use to verify the source code. This means that after exhausting all options the developer has no choice but to merge the code segment with other units (Software Testing). Â  Integration testing involves testing combined parts of an application to determine if they function correctly together. Integration testing is performed after unit testing and before system testing. Integration testing is necessary to identify faults in the interaction between integrated units. Test stubs and test drivers are useful in performing integration testing (Tutorials Point). Â  When manufacturing a ballpoint pen, the body, the cap, the clip and tail, the ballpoint, and the ink cartridge are unit tested separately. When the units are ready, they are assembled and integration testing is performed. For instance, one would test whether the cap fits into the body (Tutorials Point). Â  Big bang approach involves combining all or most of the units together and testing them together.

Ielts Essays Essay Example for Free

Ielts Essays Essay 1. Sample essay: Every week millions of people buy lottery tickets, hoping their small investment will make them rich. They often believe that if they won a million dollars, their troubles would be over. If they actually got the money, would their dreams come true? Whether people live happily ever after when they win the lottery probably depends on what their dreams are. Money can buy some things but not others. Cash buys houses, cars, and college educations; it pays for medical treatment and clears up overdue bills. Money also purchases travel and new experiences. A million dollars could allow someone to quit a tough, boring job and try for something better. It could provide a feeling of security. On the other hand, winning so much money could actually cause some problems. A person who quit working might eventually become bored or lose some self-respect. Family members might squabble over what should be purchased. Long-lost friends, relatives, and even complete strangers are likely to want a handout. The winner must then decide whom to help and whom to offend. Despite all these drawbacks, I would rather win the money than not. The difficulties of having to manage a million dollars are troubles I would like to have. 2. Sample essay: After the baby is born, things will never be the same. People say that to expectant parents-and they are right! It will be a long time before those parents can again sleep late in the morning. A baby wakes early, screaming for food. The toddler thinks 6 a.m. is the right time to start the day. After that come early school mornings. It will be years before the parents can go anywhere together on the spur of the moment. Every outing must be planned ahead so that a baby-sitter can be found. The budget will be stretched, the work load will get heavier, and by the time parents can be alone, they may be too tired to talk. Still, people want children. Why? One reason is that children are a link to the future. They will probably be here after the parents are gone. In addition, their children will live after them. A deeper reason for wanting children, perhaps, is that the more people we have to love, the more fulfilled our lives can be. By giving to a child, people enrich their own lives. In the end, we live not only for ourselves, but for others. 3. Sample essay: It hurts to look at a paycheck and see how much of it was taken out for income tax. That money could have paid some important bills. It is easy to dream of doing away with the income tax and keeping all that money for ourselves. If there were no income tax, however, the government would have a lot less to spend. The money we send to Washington seems to fall into a black hole and disappear. Actually, though, many people depend on it. The money pays the salaries of government employees, who provide services from drug control to highway building. It supports our military defense. Also, much of the money is returned to people in the form of student loans, veterans benefits, and payments to farmers, for example. The government has been working to cut its budget lately. With every cut, someone complains loudly. So if the income tax were eliminated, other taxes would have to make up for it. Paying those other taxes would also hurt. Sales taxes fall most heavily  on poor people. Taxes on manufacturers only result in higher prices to consumers. Income taxes are not fun to pay. But doing without them would be worse. In my opinion, income taxes should be made as fair as possible. Then we each must bite the bullet and do our share. 4. Sample essay: Television has changed both the way we spend our time and what we know about the world. Some of the changes brought by television have improved our way of life, but others have made it worse. People today on the average spend several hours a day watching television. In times past, they would sit on their front steps and visit on nice evenings. This neighborly visiting built close friendships, but it seldom takes place any longer. Even though families may all watch TV together, they may not communicate much. Some women have called themselves sports widows because their husbands spend every spare minute watching televised football, baseball, and other sports. On the other hand, people have learned more about the world because of television. People in small towns know more about the city, and people in cities have learned about the country. Politicians, celebrities, wars, and disasters appear in the living room. Programs take viewers to the bottom of the sea, the tops of mountains, and even outer space. Some people think television leads to violence, immorality, and greed for possessions. I am not sure whether this is true. However, good or bad, TV is here to stay. It is up to each of us to make the most of its opportunities and avoid its problems. 5. Sample essay: When lack of money prevents us from having something we want very much, it is  tempting to dream of being rich. It is hard to keep in mind that Americans are already wealthy compared with people in many other parts of the world. Our modern conveniences would have been the envy of kings in times past. Just the same, most people would like a larger. Whether most people are capable of making a lot of money is another question. People in average circumstances can often get ahead through education, hard work, and careful money management. But getting ahead is not the same as actually becoming rich. Only a small percentage of Americans could be called truly wealthy. Some people joined this group from ordinary beginnings. Usually they have done it by carefully riding some major development in the economy on its way up. In the past, great fortunes have been made in oil, steel, and railroads. Recently, some people have made millions in computers and real estate. Usually, though, it takes money to make money. Big investors often start rich and then get richer. Most of us cannot strike oil or start the next new technical breakthrough. Most people are not born into wealthy families, either. In America it certainly is possible to become more prosperous. But unless someone wins the lottery, real wealth is not very likely to come along. 6. Sample essay: You come home alone after a long day at work. You open the door to your home. No one is there. Is it blessed silence you hear or echoing emptiness? The millions of people who live alone today may have either experience. Some love living alone, yet others wish they didnt have to. When they open that door at night, people who live alone do not have to put up with demands or listen to someones noise or meet anyones dinner deadlines. They do not have to debate about which TV program to watch or  stay off the phone because someone else is expecting an important call. No one else messes up their kitchen. But when they are sick, no one else will bring them an aspirin or call the doctor. Preparing dinner for one can be difficult, and eating dinner for one night after night can be very lonely. Perhaps no one really cares what they did all day. If they are feeling sad, there may be no one to cheer them up. Some people who live alone say the worst times come when something very good happens because there is no one to share the joy. During the course of a lifetime, one may sometimes live with others and sometimes live alone. Each way of life has its advantages. Learning to take advantage of them is one key to contentment. 7. Sample essay: Sports includes both national teams and the teams for the rest of us. The national teams are mainly concerned with winning and with money. The other teams are mainly concerned with winning and with money. The other teams provide different satisfactions. Being on a team helps people learn teamwork to rely on others and to do their own part as well. Players learn both to win and to lose. When the team loses, the members learn that they can come back from a loss. They look for the reasons they were beaten, work on their weaknesses, and try again. When the team wins, the members can learn to be gracious winners and good sports. Sports are also for play. Most of us have work to do most of the time. Now and then we need to have fun. Sports can provide the time to relax. If a team helps people learn to work together, lose win, and have fun, its a winner regardless of the score. But if players on a winning team have not worked together, if they feel that winning makes them better than others, if there was no joy in the sport, those winners are losers. Having the winning score is important. Being a winner as a person is worth even more. 8. Sample essay: Advertisers who directly attack their competitors may amuse me if they do it cleverly. However, they have probably lost me as a customer. Companies who attack their rivals remind me of people who boost their egos by criticizing others. When people do this, I often suspect they have little to offer and may even have something to hide. I would rather find out what is good about a person, not what is bad about someone else. Similarly, I like advertising that lets me know about products that might meet my needs. I dont place much faith in ads telling me what may be wrong with a rival product. I tend to suspect that the information could be biased. I also believe advertisers are foolish to name their rivals because by doing so they give the competing product free publicity. If the competition is worth attacking, I tend to think it may actually have something to offer. In advertising, as in life, I believe we should try to be the best we can be, without belittling the next person or the rival product. 9. Sample essay: Three generations living together can have both financial and personal advantages. On the other hand, it can also have personal disadvantages. In years past and today, three generations have probably lived together mostly out of economic necessity or advantage. Sometimes a young family moves in with the older generation because the husband and wife cant afford a place of their own. Sometimes grandparents move in because they arent well enough or cant afford to live alone anymore. Occasionally, grandparents come to take care of the children so both parents can work. In  times past, and sometimes today, three generations have lived together because they all depended on the same farm or business. Usually these arrangements do help solve financial and practical problems. Everyone has a roof over his or her head. Children and old people in need of care are likely to get it. Often a family can get ahead financially by sharing the work and the bills. In addition, a strong sense of family and of belonging can develop in everyone. What may be harder to work out are questions of whos in charge. If grandparents dont let go of some authority, the middle generation is likely to resent it. On the other hand, ailing grandparents may force their children to be parents to them and to their own children as well. If parents and grandparents disagree on discipline, children may be confused or angry. The personal disadvantages can be overcome. For three generations to live together successfully, everyones needs must be respected. 10. Sample essay: Television news shows are dramatic and interesting. Watching them is pleasant and does not require the effort of reading. If television did not cover the news, some people would know nothing about what is going on in the world. However, television newscasters cover only the events that they have time for, and they prefer stories that include some dramatic pictures. Viewers are quickly bored with reporters who sit and talk into the camera. As a result, a complicated story is often cut short. Newspapers and magazines do a better job of explaining complex events. They can include details, and a person with a special interest can take the time to read them. Others can stick to the headlines. Reading allows more freedom of choice than television. The TV audience cannot decide which stories to watch. In broadcasting, one size fits all.  However, a person who reads newspapers and magazines can choose to spend time on business, sports, health, or the school board election, depending on special interests. Television provides a useful glance at whats happening. However, a person who has individual interests and who wants the whole story needs newspapers and magazines as well. 11. Sample essay: Some people live in one community all their lives, while others move around almost as much as nomads. Both experiences have their advantages and disadvantages. People who stay in one spot can develop lifelong friendships, and such friends may lend a hand if trouble comes. They know each others life history, and they judge each other for the kind of person each is, not for the image each projects. Yet spending a lifetime in one location can also lock a person into a limited way of life. Personal change may become very difficult. People with few experiences may develop a narrow outlook and find it hard to understand those who have different ethnic, racial, or religious backgrounds. On the other hand, moving to different parts of the country is usually stressful. A person may feel lost and uprooted in a place where streets, stores, schools, and churches all are different. At first there are no friends to help. However, those who do move learn that people in other places have a variety of outlooks. There is a chance to appreciate different ways of life and even to choose the way one likes best. For a person who moves to a different place year after year, the disadvantages of moving probably outweigh the advantages. But a few moves  are probably worth the effort. By staying in each place for a length of time, people can broaden their outlook but have enough time to make adjustment and form friendships. 12. Sample essay: The automobile has probably changed peoples way of life more than any other invention of the last century. More than electric lights, television, air travel, or even computers, automobiles have changed where people live and work, how they make a living, and even how they find a mate. Before there were cars, people generally traveled on foot or by horse and buggy over unpaved roads. Whether they lived in the city or the country, they rarely went farther than a few miles from home. They saw the same people and places year after year. The car opened up whole new worlds. Roads were paved, and motorists went to see different parts of the country. Some decided to stay. People with cars could live farther from their jobs, and so the age of commuting began. New suburbs sprang up around the cities. The auto industry boomed, and millions of Americans made a living manufacturing, selling, servicing, or insuring cars. As more people got cars, your people began driving them. No longer was courtship confined to the girls front porch, under the watchful eye of her parents. The automobile began the sexual revolution. Some people believe that commuting, suburban life, and courting in cars are mixed blessings. Whether the changes are good or bad, they seem to be here to stay. 13. Sample essay: Many people complain that modern society is too materialistic. Other people, they say, place too great an importance on material property. Rather than  value values, these critics insist, people today value things. There is no doubt that we live in a material, consumer-oriented society. In economic terms, consumers use products; in everyday language, they acquire things: TVs, cars, clothes, furniture. This kind of materialism can actually be good for a society since it helps create jobs. When people have jobs, they acquire self-respect along with the money they need to provide the material things they and their families require. It is true, on the other hand, that many people have taken healthy consumerism too far. Materialism is evident when an otherwise intelligent person goes into debt charging things that he or she cannot pay for. Materialism is evident when people insist on buying a particular designer label even though the same quality can be found in a cheaper product. Materialism is evident when people are judged and admired for what they own rather than what they are or can do. Even if society has gone too far in the direction of materialism, as some say, the individual person doesnt need to surrender. He or she can still value honesty, integrity, freedom, talent, quality, and all the other values there are to value and leave the materialism to others. 14. Sample essay: People spend a great deal of time, money, and energy to see or read about movie stars, TV actors, singers, and athletes. Such celebrities often become idols. Posters, T-shirts, fan clubs, and attendance at live performances prove that. What do celebrities do to merit this attention? Celebrities create excitement. They create excitement because they have done something or can do something that supposedly not everyone else can do. Raising a child, waking early to go to work each morning, building a home and a place in the community-these achievements actually deserve more admiration than rolling through Beverly Hills in a limousine or jetting across the Atlantic to star in a new movie. Yet because these achievements  are part of many peoples everyday lives, they are not considered special. Celebrities help us dream by lifting us out of our everyday lives and imagining ourselves doing other than everyday activities. Celebrities also set styles. They become models for behavior, clothing, and hairdos. Just consider Elvis Presley or the Beatles, for example. Celebrities also influence politics, as Bob Hope and Robert Redford have done. Celebrities roles as special people and trendsetters, then, are the reason for the attention many of us lavish on them. In many ways, the celebrities of today have merely replaced the kings and queens of old. 15. Sample essay: Most people want to be successful in life, but success can come about in four ways: fame, money, knowledge, and pleasure. Success is also usually characterized by the word more; to be successful, people feel they have to be more famous, have more money, absorb more information, or enjoy life more. Success does not need to be characterized by quantity, however. Instead, you can measure the success of your life by its quality. It is not important, for example, how many people know you but who knows you and for what. Working in your community or on good relationships with family and friends can bring quality fame. Earning less money but spending it wisely and learning the joy saving is another way to succeed. Learning more so that you can turn around and teach someone else produces quality knowledge. And finally, all the above will most likely bring you quality success in enjoying the pleasures of living. Success, in conclusion, can be seen in different ways by different people. Only one thing is sure. No matter what other people see, the only one who knows whether youre succeeded is you. 16. Sample essay: Every year billions of dollars are spent on advertising. Many approaches are used to persuade consumers to buy a product. Some seem to work better than others. One approach, for example, is to try to make the reader or viewer identify with the people shown using the product. These people seem to be glamorous, loved, successful, elite, clever, or sexy. Supposedly, anyone who uses the product can expect the same reward. Another approach is to let the product speak for itself; people are attracted to scrumptious food, beautiful clothing, and sleek new cars. Sometimes good prices and special deals are the focus. Ads for complicated products, such as computers, may provide a lot of information. Endorsements by celebrities are especially common. In general, many of the ads succeed. People do tend to buy what they see advertised. However, some advertising can backfire. People may be offended, for example, by ads that are overly sexy or ones that viciously or sarcastically attack competitors products. Advertising can be a useful aid for the consumer. It helps a person learn what is new or in style or handy to have around, what things cost, and where to buy them. To use this information effectively, however, a person must learn to look past the emotional appeals and find the facts. 17. Sample essay: Some animals are pets, some are wild, and many of them provide us with food. All have a different and important role in our lives. It is easy to forget that the steak at the supermarket once formed part of a steer. But without domestic animals such as chickens and cattle, we would all be vegetarians, or a great deal of our time would need to be spent hunting. Wild animals attract sport hunters. For some people they are even an  important source of food. When urban people visit the wild, deer, bears, and other wild animals remind them of an older way of life. Pets, however, are the animals that are especially significant for most of us. They are undemanding companions; they love us when we are not at our best. A pet can be a great comfort when life seems hard. For children, pets can be both fun and instructive. If a child cares for a pet, he or she learns to take responsibility for another being. Watching kittens or puppies being born can be a natural form of sex education. For children, as for adults, pets are loving companions and a help in tough time. As I recall, an Indian chief once said, Without our brothers, the animals, we would all be very lonely. I believe he was right.

A Introduction To Satellite Television

A Introduction To Satellite Television Satellite television first the consumer market in the early 1990s. Dishes made for the average household were expensive and took up a lot of space in the garden. I n the first few years of satellite TV only the wealthiest, or more die-hard fans of television, would go to the trouble of buying and setting up a satellite dish. Satellite television was also a lot harder to get than cable or broadcast TV. In the present day you see satellite dishes on the rooftops of most homeowners in the UK and indeed the rest of the western world. The major satellite TV companies are getting more and more people to buy their product with promises of films, sports and especially news from around the world. The advancement into high-definition televisions and being able to get a high definition satellite signal has made it even more prominent. Satellite Television gives us many solutions to the problems that come with broadcast TV and, although not perfect itself, is now the main way to view television. In its basic form satellite television is a lot like broadcast television. They are both a wireless system for delivering television programming to a viewers house. And they both use satellite stations to transmit programming via a radio signal. Using powerful antennas broadcast stations transmit radio waves to the area surrounding them. The viewers, however, pick up the signal with a much smaller antenna. Broadcast television works fine it just has one massive drawback, which is range. When a broadcast antenna shoots out a radio signal it is shot out in a straight line. To receive these signals you have to be in the direct line of sight of the antenna. If you are not the signal may become distorted. Small obstacles such as trees or small buildings should not be a problem but bigger obstacles, such as planet earth, would pose a problem. If you transmitted a broadcast signal over a perfectly flat surface you would be able to pick up a signal thousands of miles away from the source. However in the real world the curvature of the planet distorts and blocks the signal sent out from the satellite, to get a perfect signal you would have to be close to the antenna with no obstacles in between. The Satellite TV Solution Satellite TV solves this problem by transmitting signal from satellites orbiting the Earth. Because these satellites are so high in the sky it means there are a lot more customers in range and line of sight. Satellite TV systems transmit and receive radio signals using specialized antennas called satellite dishes. Diagram of how Satellite TV works . When the satellites that broadcast these radio signals are sent up in to space they are all sent up in geosynchronous orbit. This means that they all stay in one place in the sky relative to the Earth. Some facts: Every satellite is launched into space at 7000mph Each one reaches about 22,200 miles above the Earth. When the satellite is this high and moving at such a speed it will revolve around the Earth once every 24 hours, keeping it in the same position above the Earth giving constant signal to the viewer with uninterrupted signals. The Components of Satellite TV In a DTH (direct to home) or DBS (direct broadcasting) satellite system there are five major components. These are the programming source, the broadcast center, the satellite, the satellite dish and the receiver. Programming source this is where the channels that provide the programmes are based. This is where the satellite TV providers go to pay other companies (for example MTV or Nickelodeon) for the right to broadcast there programmes through their satellites. Broadcast Center The broadcast center is central part of the system. In the broadcast center the people who are providing the TV to the viwers at home receive signals from different programming sources and then beam a broadcast signal to satellites to geosynchronous orbit. Satellites The satellites in space receive the signal sent from the broadcast center and beam them back down to Earth. Dish The viewer then picks up this rebroadcasted signal and the satellite dish passes it onto the receiver in the house. Receiver All the receiver then has to is process the signal and pass it on to a standard TV. This is a very good system to providing a good quality signal to a large area. It has very picture display and sound quality with hundreds of channels and the service is ready to use in rural and urban areas and provides a lot of access to digital and high definition programming. However satellite is not without its drawbacks. It can be quite expensive to buy all the equipment at the outset (satellite dish and receiver etc) and if you want to access satellite television in multiple rooms in your home be prepared for the extra cost. As well as this satellite television can be subject to extreme weather conditions. Satellite TV signals Satellites signals have a very long way to travel before they appear on your TV screen. Because of this and because they contain very high-quality digital data it would be near impossible to transmit them without compression. Compression is defined, in this case, as removing all unnecessary or repeated information. After the signal is transmitted it is reconstructed. Satellite TV has to use a very unique type of video file compression standardized by the Moving Pictures Experts Group or MPEG for short. This allows the provider to successfully transmit significantly more channels than without using this method of compression. MPEG standards exist to promote interoperability among your computer, televisionand hand held video and audio devices. These MPEG standards are: MPEG-1: this is the original standard. It is used for encoding and decoding streaming video and audio files. MPEG-2: this standard compresses files which are used and transmitted for a high quality of video and is the standard for digital television. MPEG-4: the function of this standard is to compress high definition video onto a smaller scale so you can stream it to computers, mobile phones and PDAs. MPEG-21: This standard basically interprets digital content so that the media plays flawlessly no matter what machine it is, what language it is in or the user conditions. It is also referred as the Multimedia Framework. Most satellite TV providers used to use the MPEG-2 standard to compress their signals but changed to the MPEG-4 standard of compression. This is because MPEG-4 is more efficient at encoding can provide a much greater bandwidth than MPEG-2. However MPEG-2 still remains the official standard for digital television. This is because it is more able to analyse static images, like those you would see in such programmes like talk shows or newscasts whereas MPEG-4 is better at analysing moving, dynamic images. MPEG-4 can do this through such things as spatial  [1]  and temporal  [2]  compression. This is how satellite TV manages to provide such a high quality picture of fast-moving objects on the screen, that are always moving, like in a football game. Satellite Dish When the signal reaches the viewers house it is captured by the satellite dish. The satellite dish is made up of an aparabolic (bowl-shaped) surface and a central feed horn. The signal passes through the horn and then the dish focuses the signal into a narrow beam. This receiving dish works in the exact opposite way to the transmitter as it cant transmit information, it can only receive it. The dish acts just like a concave mirror in that the shape of the dish reflects the signal inward onto a particular point just like a concave mirror focuses light onto a particular point. The dishes feed horn feeds the signal on to the receiving equipment, and if there hasnt been any obstacles between the satellite and the dish there should be a perfect signal coming into the viewers receiver (unless the weather is bad). Before the dish sends the signal to the viewers receiver it amplifies and filters the signal using LNB, or low noise blockdown converter. After this the LNB passes the amplified, filtered signal to inside the house. Sometimes, in some systems, the dish needs to pick up a signal from two different satellites. Sometimes this may be possible but when it isnt it may compromise the quality of the signal because the dish cannot be aimed at both of the satellites at the same time so either one or both of the signals would be distorted. Satellite Receiver At the end of the satellite TV system is the receiver. It has four important jobs: It takes the encrypted signal and de-scrambles it It takes the digital MPEG-2 or MPEG-4 signal and changes them into an analog signal so the standard television can recognize It also has to sort out the individual As well as this it keeps the providers headquarters up to date with the payments the viewer owes the provider of the satellite television. Conclusion After closely studying satellite television and how it works it is clear to me that is much better and more practical then the older normal broadcast television. This is because of the greater range and line of sight that satellites have got rather than the regular antennas which are impeded by the curvature of the earth and even small obstacles. Although satellite television does have some drawbacks I would say it is definitely the way forward in television broadcasting and has already nearly taken over the market.

Marijuana vs. Cigarettes: Why is one legal? Essay -- Harmful, Brain,

Marijuana and Cigarettes are both things that all Americans have heard about. Man untrue ideas have been spread about both products. Marijuana is not legal and it may not be as harmful as cigarettes. Marijuana is less harmful to the brain, body, and environment than cigarettes. When someone smokes a cigarette they say they feel a sensation all over their body. Users may experience different feelings. Many people say it creates a relaxing feeling all over the body, some say it helps to clear their head, and some say they like the taste of the cigarette. Marijuana creates a different sensation in the body. Marijuana can be used in different ways including using a bong, a pipe, or rolling it into a hollowed out cigarette called a joint or blunt (American Lung Association). When users smoke marijuana they say it creates a high sensation. This sensation is described as making the user feel floaty, a distorted sense of time, haziness, increased hunger, happy, giggly, and dizziness. Some people have reported hallucinations from high doses of marijuana. Occasionally users say it has made them anxious, panic, or feel distrustful (Volkow). They say the effects last around two to four hours. All of these effects vary from person to person and the amount of marijuana inhaled. The ingredients used in Cigarettes and Marijuana are very different. The main ingredient in cigarettes is tobacco however it does not make up a cigarette alone. Cigarettes can have 600 ingredients, including vinegar, rocket fuel, sewer gas or paint (Tri-County Cessation Center). Marijuana is solely made of the plant Cannabis sativa. The active ingredient in Cannabis sativa is delta-9-tetrahydrocannabinol (THC). This ingredient is from the plant alone with no additi... ...on, 2014. Web. 20 Feb. 2014. . â€Å"New Study Shows Smokers Underutilize Proven Treatment and Services For Quitting.† Centers for Disease Control and Prevention. N.p., n.d. Web. 27 Feb. 2014. . Tri-County Cessation Center. N.p., n.d. Web. 20 Feb. 2014. . Volkow, Nora D., M.D. â€Å"Marijuana Abuse.† National Institute on Drug Abuse. N.p., July 2012. Web. 19 Feb. 2014. . â€Å"Youth and Tobacco Use.† Centers for Disease Control and Prevention. N.p., 14 Feb. 2014. Web. 24 Feb. 2014. .

Compensation

Compensation is an important motivator when looking to achieve desired organizational results. Money is thought of s a powerful motivator, however that only holds for sometime until the next pay increase is due. Compensation strategies reinforce the organizational culture that you desire, this enables the culture where pay is linked to performance. To ensure this process works, it must be reflected in the strategic business objectives. The objectives must clearly be defined, must be communicated as soon as decision has been reached.By doing this proper, the organization can motivate employees and make them want to perform better. CONTENT An incentive plan is defined as a formal scheme used to promote or encourage specific actions or behavior by a specific group of people during a defined period of time. So what are the reasons so many companies would find a need to offer such incentive plans? Some of the top reasons are, for motivation, company morale, company loyalty, increased prod uctivity, increase achievement, reduced absenteeism, reduce company cost, decreased turnover and to create more team work.The organization I am employees with created for both union and non- urn employees an incentive compensation plan. When developing this plan it was to focus on two major points, safety and waste reduction. It was then also decided that a third element would also be counted, improved productivity. In order to receive the incentive there were requirements; you need to be a full time Compensation-Bemires 3 employee, employed for the last three (3) consecutive months and be actively employed at the time of payout, which was quarterly.There are also goals that need to be reached in order to collect the incentive for that portion of the goals. The safety component is that the TRIP (total recordable incident rate) needs to be low. Following the guidelines as noted: Greater than 1. 50 payout was O 01 -? 1. 50 payout is 1% of quarterly wages less than 1. 01 payout is 2% o f quarterly wages As a company this component is important because the safety of the employees is and will always be the most important thing to the company. Their safety should come first not only to Bemires but also to the employees.It was after looking at these aspects that a separate incentive plan needs to be created just for the non-union/salary employees. The SHIP (salaried performance incentive plan) needs to be created for salary personnel of the Bemires Company. It is intended to provide an incentive for employees to perform their jobs at the highest level possible to facilitate achievement of division and Compensation-Bemires 5 the plant goals, contributing to overall profitability.This plan was designed to reward individuals with additional annual cash compensation in recognition of their individual and collective efforts to meet or exceed annual goals. Unlike a merit increase which is an increase to your salary based on demonstrated ability to meet job responsibilities over an extended period Of time, incentive award is based on annual performance, targeting specific areas which may change from year to year. Employees must be regular full time employees, must be active employees t time of distribution.Eligibility does not necessarily entitle a participant to an award and does not constitute an agreement with the company. In making the requirements for this SHIP incentive it will depend on many factors which include, the individual base salary earnings for the eligibility period, normal reward percent, performance rating given by employees superiors, all targets/measurements are meet, and funding scale. The following are the factors to determine each of these. Base salary earnings: amount of pay a participant received throughout the plan year in eligible base earnings excluding all other forms of compensation.Normal award percent: each participant is assigned a normal award percent for his/her position; employees will be notified of this percentage . Normal award: is the base dollar amount of incentive eligible to the participant, it is then impacted up or down by individual performance rating and the results Of the profit and other targets set for the plan year. Individual performance rating (l PR): this will be given by the supervisor and can range from . 500 up to 1 250, the PR should correlate to the overall performance of the Compensation-Bemires 6 employee based on their yearly appraisal.

Outline Types for Research Papers

Outline Types for Research Papers Outline Types for Research Papers Your first step when writing a research paper is the outline. It helps you arrange your thoughts and keeps ideas coherent. Whether the paper is meant to be a lengthy discussion or a short presentation, an outline is a useful guide for the writer. There is no single, correct way to write an outline. The best outline is one you’re comfortable creating and is appropriate for the assignment. Here are some types of outlines for research papers: Informal Outline Starting with an informal outline will help you concentrate and list your thoughts. You’ll discover which points you’d like to emphasize, the details you lack, and how you’d like the paper to look. The informal outline consists mainly of words or phrases, with only bullets or numbers as a format. This kind of outline is especially handy when you’re pressed for time and need to draft something quickly. Formal Outline When writing a more formal or longer paper, or when you have more time to prepare the work, constructing a formal outline is a good idea. You can begin with an informal outline and transform it later With a formal outline, a specific format must be followed. Roman numerals, letters and numbers are used to organize the ideas. The phrase or sentence structure of the main points and supporting points must be the same. Both formal and informal outlines can be further expanded to form topic or sentence outlines: Topic Outline In a topic outline, your ideas and explanations are sorted and distributed into different parts. Each part focuses on a certain topic (written in phrase form), and enumerates the details below. The usual format for topic outlines is Roman numerals for the main points, capital letters for the topics under each main point, and numbers for those under the sub-topics. Sentence Outline The sentence outline presents (in sentence form) the proofs supporting your thesis statement. The summary of the entire research paper is embodied in the sentences of this outline. The main points are labelled with Roman numerals, the supporting points for each labelled with capital letters, and details for each supporting point labelled with numbers. Reverse Outline While formal and informal outlines are created before the actual writing of the paper, the reverse outline is developed when you’re done with an initial draft. It can be used to check: If the draft accomplishes its purpose If all key elements are present If the order of ideas makes sense To create a reverse outline, determine the main idea of each of your paragraphs. When combined, they should form the summary of your thesis statement. Following an outline helps you keep ideas clear and that you don’t neglect any important information. There can be instances when you need to make changes or add to your outline, but your main points should remain the same. If you need assistance drafting any research papers, in Ontario and Canada is available for your academic needs. Our team is committed to helping you compose, proofread, and edit your essays.

Oragan Transplants essays

Oragan Transplants essays Now you have to realize that we are in a no win situation with the issue of organ transplants. It isnt fair, and there is no way we can make it completely fair until there are enough organs available to satisfy the demand for them. Some people are just not going to receive a transplant, and there is nothing we can do about that right now. Dividing people into three classifications, and listing them according to that, will maximize the efficiency by which we distribute our limited supply of organs, and minimize the loses we are incurring because of the organ shortage. Some would say this system is not fair to the people on the secondary and tertiary lists, because if the primary list is big enough to use all of the available organs, then the people on the other lists will most likely die. Well, people are dying anyway while waiting for organs, and yes it is unfair that people have to die, but it is even more unfair when somebody dies who needs a new liver through no fault of their own, and an alcoholic who has boozed their life away, takes that liver and lives. Who in their sober right mind would call that fair? Who has the right to judge which people die or not? You and I are not some god-like figure, so we dont have the right to do that. I would completely agree with these critics about nobody have the right to judge other people, but these lists are not judging anybody. By choosing to participate in certain activities, or not, people are ultimately deciding their own placement on these lists. They arent be judged by anybody, just categorized by their lifestyles. In other words, people would simply be taking responsibility for their actions. If one chooses to get consume large amounts of alcoholic beverages every night until they need a new liver, then that is their own choice, and they should pay the consequences for it. If it means death, so be it. They had their chance with life,...

Greed and Taxation Led to the Fall of Rome

Greed and Taxation Led to the Fall of Rome Whether you prefer to say Rome fell (in 410 when Rome was sacked, or in 476 when Odoacer deposed Romulus Augustulus), or simply morphed into the Byzantine Empire and medieval feudalism, economic policies of the emperors had a heavy impact on the lives of the citizens of Rome. Primary Source Bias Although they say history is written by the victors, sometimes its just written by the elites. This is the case with Tacitus (ca. 56 to 120) and Suetonius (ca.71 to 135), our primary literary sources on the first dozen emperors. Historian Cassius Dio, a contemporary of Emperor Commodus (Emperor from 180 to 192), was also from a senatorial family (which, then as now, meant elite). Commodus was one of the emperors who, although despised by the senatorial classes, was loved by the military and lower classes. The reason is mainly financial. Commodus taxed the senators and was generous with the others. Likewise, Nero (Emperor from 54 to 68) was popular with the lower classes, who held him in the kind of reverence reserved in modern times for Elvis Presley- complete with Nero sightings after his suicide.   Inflation Nero and other emperors debased the currency in order to supply a demand for more coins. Debasing currency means that instead of a coin having its own intrinsic value, it was now the only representative of the silver or gold it had once contained. In 14 (the year of Emperor Augustus death), the supply of Roman gold and silver amounted to $1,700,000,000. By 800, this had dwindled to $165,000. Part of the problem was that the government would not permit the melting down of gold and silver for individuals. By the time of Claudius II Gothicus (Emperor from 268 to 270), the amount of silver in a supposedly solid silver denarius was only .02 percent. This was or led to severe inflation, depending on how you define inflation. Especially luxurious emperors like Commodus, who marked the end of the period of the five good emperors, depleted the imperial coffers. By the time of his assassination, the Empire had almost no money left. The 5 Good Emperors Leading to up Commodus 96 to 98: Nerva  98 to 117: Trajan  117 to 138: Hadrian  Ã‚  138 to 161: Antoninus Pius  161 to 180: Marcus Aurelius177/180 to 192: ​Commodus Land The Roman Empire acquired money by taxation or by finding new sources of wealth, like land. However, it had reached its furthest limits by the time of the second good emperor, Trajan, during the period of the high empire (96 to 180), so land acquisition was no longer an option. As Rome lost territory, it also lost its revenue base. Romes wealth was originally in the land, but this gave way to wealth through taxation. During the expansion of Rome around the Mediterranean, tax-farming went hand-in-hand with provincial government since the provinces were taxed even when Romans proper were not. Tax farmers would bid for the chance to tax the province and would pay in advance. If they failed, they lost, with no recourse to Rome, but they generally made a profit at the hand of the peasants. The diminishing importance of tax-farming at the end of the Principate was a sign of moral progress, but also meant the government couldnt tap private corporations in the event of an emergency. The means of acquiring crucial monetary funds included debasing the silver currency (seen as preferable to increasing the rate of taxation, and common), spending reserves (depleting the imperial coffers), increasing taxes (which was not done during the period of the high empire), and confiscating the estates of the wealthy elite. Taxation could be in kind, rather than coinage, which required local bureaucracies to make efficient use of perishables, and might be expected to produce reduced revenue for the seat of the Roman Empire. Emperors deliberately overtaxed the senatorial (or ruling) class in order to render it powerless. To do this, the emperors needed a powerful set of enforcers- the imperial guard. Once the wealthy and powerful were no longer either rich or powerful, the poor had to pay the bills of the state. These bills included the payment of the imperial guard and the military troops at the empires borders. Feudalism Since the military and the imperial guard were absolutely essential, taxpayers had to be compelled to produce their pay. Workers had to be tied to their land. To escape the burden of tax, some small landowners sold themselves into slavery, since slaves didnt have to pay tax and freedom from taxes was more desirable than personal liberty. In the early days of the Roman Republic, debt-bondage (nexum) was acceptable. Nexum, Cornell argues, was better than being sold into foreign slavery or death. It is possible that centuries later, during the Empire, the same sentiments prevailed. Since the Empire wasnt making money from the slaves, Emperor Valens (ca. 368) made it illegal to sell oneself into slavery. Small landowners becoming feudal serfs is one of the several economic conditions  responsible for the fall of Rome. Resources and Further Reading Barnish, S. J. B. â€Å"A Note on the ‘Collatio Glebalis.†Ã‚  Historia: Zeitschrift Fà ¼r Alte Geschichte, vol. 38, no. 2, 1989, pp. 254-256.  JSTOR.Bartlett, Bruce. â€Å"How Excessive Government Killed Ancient Rome.† Cato Journal, vol. 14, no. 2, 1994, pp. 287-303.Cornell, Tim J. The Beginnings of Rome: Italy and Rome From the Bronze Age to the Punic Wars (c. 1000-264 B.C.). Routledge, 1995.Hammond, Mason. â€Å"Economic Stagnation in the Early Roman Empire.† The Journal of Economic History, vol. 6, no. S1, 1946, pp. 63-90.Heather, Peter. Fall of the Roman Empire: A New History of Rome and the Barbarians. Oxford University, 2014.Hopkins, Keith. â€Å"Taxes and Trade in the Roman Empire (200 B.C.-A.D. 400).† Journal of Roman Studies, vol. 70, Nov. 1980, pp. 101-125.Mirković Miroslava. The Later Roman Colonate and Freedom. American Philosophical Society, 1997.West, Louis C. â€Å"The Economic Collapse of the Roman Empire.†Ã‚  The Classi cal Journal, vol. 28, no. 2, 1932, pp. 96-106.  JSTOR.Wickham, Chris. â€Å"The Other Transition: From the Ancient World to Feudalism.† Past Present, vol. 103, no. 1, 1 May 1984, pp. 3-36. Woolf, Greg. â€Å"Imperialism, Empire and the Integration of the Roman Economy.† World Archaeology, vol. 23, no. 3, 1992, pp. 283-293.

Crisis communications plan Essay Example | Topics and Well Written Essays - 500 words

Crisis communications plan - Essay Example Hence, appointing an experienced Public Relations Officer to take charge of CCP is vital to its success. A good crisis communication plan will contain the following key elements. First, it should have gotten the endorsement of the Director of Communications. Second, it should contain a list of clearly designated employee responsibilities. The information contained in the plan would have gone through verification and clearance checks. It will include a lits of media contact points and also contain details regarding local public health agencies. The plan will clearly identify who the spokesperson is going to be as well as identifying members of the Emergency Response Team. The efficiency and speed with which the crisis is dealt with is in itself a key element (and the first step) of a good plan. Later, the drawn up plans need to be communicated to the stakeholders through proper Public Relations procedures. This usually involves publication and coverage of the crisis in media outlets s uch as newspapers and television stations. In most instances, a crisis situation never gets covered in the media, probably because the story is not newsworthy.

Importance of Intellectual Capital Essay Example | Topics and Well Written Essays - 1000 words

Importance of Intellectual Capital - Essay Example Intellectual capital produces wealth through information technology and also encourages business leaders to become critical analysts of economic trends specially those factors associated to finance, performance management, production, distribution, marketing and other related exchanges in trade flows, investment, and human resource management. It also hastens wise decision-makings on matters affected by political and market behaviours. These days, business enterprises rely on information capital as technologies have elaborately underscored the role of information, knowledge and experiences for economic activities. It’s in this context too that the world’s economy transitioned itself from simple dependency on science and technology to an economic system that considered the production of knowledge as primary factors for business management. Nowadays, intellectual capital is considered as the most valuable asset in this era of information. Business leaders would opt for hu man resources that have strong cognitive skills and the capacity to undertake market research and finance analysis. Moreover, the operation of a corporation require intensive and accurate reporting of all offices or departments to know results and which will form part in the planning for execution, and auditing – processes that are integral to effective corporate governance. Experts opined that investors and information users would certainly delve into the reasonableness of justification, for instance, in accounting information. The latter is needed for financial and operational decision-making which may cover issues on investments, credit, management stewardship, resource allocation and corporate responsibility. Thus, shareholders would demand documented accounting to determine growth, return of investments, risks, capital gain or profit, for stock options or for rewards. For monitoring purpose and management concern, quality accounting information is necessary to ascertain collation, litigation, or political costs, including concern for competitive leveraging. Such wide information is required in managing business to enforce regulatory measures to protect and control business interests. 2. Why investors and other information users search for intellectual capital information from other sources? Investors search for intellectual capital to ascertain that their investments will be managed well. This relates to business sector’s interest to be certain that the company they collaborate or partner with have the capacity to professionally manage assets, real estates, or securities -- which include bond and debt instruments. With financial stability and profits as goals, investors and information users will also be interested that the intellectual capital of the company can wield demanded performance that warrants better if not excellent corporate standing of a company. As such the company will also be evaluating to assess financial viability, to deter mine business leadership and to secure return of investments. Thus, for company seeking more capital investments, disclosure of financial status offers corporate reputation; inspire third party certification that will show its compliance or adherence to legal requirements. A corporation with business integrity could assert corporate control

Technology and the Teacher PowerPoint Presentation

Technology and the Teacher - PowerPoint Presentation Example With every new advancement in technological tools they tend to become even more interactive and attractive for their users. These tools are immensely effective in the classroom. It is expected that each of the tools would enhance the delivery of lecture on the instructor’s side and would enable ease of understanding on the side of the student. Acting as a helping hand for the teacher, these tools aide in delivering the concept with the help of embedded techniques within them that may practically be impossible for the teacher to deliver personally or merely with the use of hand. The speed and flexibility associated with computers enables the representation and comprehension of concepts via digital imaging. The student dragging and clicking the mouse and the digital response that the learning software generates invokes the understanding and responses of the students themselves. The ability to zoom in on images, rotation of figures and embedding of animated characteristic features like avatars etcetera enable imagination of the students to extend way beyond the written text and conventional methods of teaching. The ability of digital tools to scale real world objects into many forms is one of their major advantages. The manner in which digital classroom tools encompass a variety of information within themselves that practically has limitless boundaries enables the transmission of a large variety of information in much less time duration. The plan to manage technology tools like Prezi in the classroom is to use it in combination with the verbal lectures that are directly transmitted to the students. Prezi is designed to be a cloud based software application that enables the creation of presentations on a virtual canvas. As an example a lesson plan about teaching the concept behind â€Å"The Water Cycle† is attached at the following

INVESTMENT AND PORTFOLIO MANAGEMENT Assignment Example | Topics and Well Written Essays - 2000 words

INVESTMENT AND PORTFOLIO MANAGEMENT - Assignment Example The investor who prefers to bank his funds to generate a fixed ‘certain’ interest at the end of a term is the classic case of risk-averse individual while a casino gambler who bets against high ‘uncertain’ odds is at the other end of the spectrum (Pietersz, 2009). In scenario whereby an individual investment is assured of a  £500 return, in the uncertain situation, a bet is considered that with a toss of a penny, the individual can get  £1,000 or naught, while in the certain situation the individual will definitely receive the  £500. Although both situations have a guaranteed return of  £500, the uncertain situation has a 50 percent chance of garnering  £1,000 or nothing. Therefore, three possible scenarios emerge: Risk aversion is therefore a characteristic case of martingale effect whereby the most likely scenario is the investor risk-taker only gaining the original amount (Yates, 2009). In modern portfolio theory, risk aversion is calculated as the added subsidiary return an investor needs to admit supplementary risk, which is calculated through the standard deviation of the ROI or the square root of its variance (Baker, 2001). Modern portfolio theory established mean-variance efficient portfolios in a fixed time horizon that ignored future market movements hence not applicable to multi-period investment horizon. Sharpe (1964), Lintner (1965) and Mossin (1966) separately have been ascribed to establishing the Capital Asset Pricing Model (CAPM) model that was developed from Markowitzs (1959) exposition of the Modern Portfolio Theory (MPT) particularly the mean-variance model. The fundamental theory of the CAPM indicates that there is a linear link involving systematic risk, as measured by beta, and projected share returns (Brewton, 2009). The CAPM model endeavours to illustrate the linkage by applying beta to describe the differences involving the likely proceeds from shares and share portfolios (Laubscher, 2002, p.

History of the English Language Essay Example | Topics and Well Written Essays - 500 words

History of the English Language - Essay Example did not take place overnight since the language developed over hundreds of years with influences from many different languages therefore it has interesting origins. The English language began to form with the arrival of three Germanic tribes who invaded Britain in the fourth century. The three tribes were the Angles, the Saxons and the Jutes and came from the northern areas of Germany. The Celtic language speakers of Britain were repelled by the invaders to areas of Wales and Scotland (Wells, 1982). At the same time, the language of the Angles tribe became the predominant language of the region from which the words England and English are taken (English Club, 2006). The language developed into what we know as ‘Old English’. This language would be difficult if not impossible for us to understand since there would be many more modifications to the language before it would develop into modern English. Even so, many of the words we use in English today have their roots in Old English. For instance words like Strong and Water come from Old English even though they are in common use today (Wells, 1982). In 1066, the same tribes were conquered by William the Conqueror who came from the area of Normandy which is in modern day France. He and his forces spoke a version of French which was used in the royal court while the lower classes spoke English with a mixture of French words. This version of English came to be known as Middle English and was used by Chaucer to write his Canterbury tales. It is difficult for modern speakers of English to understand or read this language but it does show how French words came to be accepted in English use (English Club, 2006). Modern English as we see it today has two distinct periods of development, the first is the early period which lasted from 1500-1800 where changes were made in pronunciation, character use and many more words were added to English. With the coming of the Renaissance, words from classical languages found

Historical events of the US Essay Example | Topics and Well Written Essays - 1250 words

Historical events of the US - Essay Example The conventional Protestant spiritual groups set up religious bases in Asia and Africa, as well as over 450 missions in China by the year 1900.The 20th century started with the US entangled in a severe and bloody war. However, that war is no longer remembered, a war that cost millions of dollars, thousands of lives and displacement of millions. ThePhilippine-American War that was fought between1899 to 1902 resulted in approximately 265,000 human deaths. Thewarassistedthe US establish itself as a military powerhouse in the Pacific regions. While the European powers were engaging themselves in the First World War (WWI), the then president of the US Wilson Woodrow was apprehensive that Germany might take up Haiti and destabilize the pathway leading to the Panama Canal. In order to assert and protect its interest, Wilson sent a few hundred US Marines and Navy men to Haiti. In 1898 and 1899, The US took over Hawaii and obtained the Philippines, Puerto Rico, and some parts of the Pacific I slands. Theexpansionraisedthesignificantquery of if their recently annexed states would be given the American citizens civil rights. HavingwonboththeSpanish-American War and Philippines War symbolized both an addition to earlier expansionist desires and a quick departure from suppositions that had steered American foreign strategy before. Fortheveryfirsttime, the US made significant strategic dedications in the Far East; acquiring regions that had never been planned for statehood, and dedicated itself to law enforcement actions.

INVESTMENT AND PORTFOLIO MANAGEMENT Assignment Example | Topics and Well Written Essays - 2000 words

INVESTMENT AND PORTFOLIO MANAGEMENT - Assignment Example The investor who prefers to bank his funds to generate a fixed ‘certain’ interest at the end of a term is the classic case of risk-averse individual while a casino gambler who bets against high ‘uncertain’ odds is at the other end of the spectrum (Pietersz, 2009). In scenario whereby an individual investment is assured of a  £500 return, in the uncertain situation, a bet is considered that with a toss of a penny, the individual can get  £1,000 or naught, while in the certain situation the individual will definitely receive the  £500. Although both situations have a guaranteed return of  £500, the uncertain situation has a 50 percent chance of garnering  £1,000 or nothing. Therefore, three possible scenarios emerge: Risk aversion is therefore a characteristic case of martingale effect whereby the most likely scenario is the investor risk-taker only gaining the original amount (Yates, 2009). In modern portfolio theory, risk aversion is calculated as the added subsidiary return an investor needs to admit supplementary risk, which is calculated through the standard deviation of the ROI or the square root of its variance (Baker, 2001). Modern portfolio theory established mean-variance efficient portfolios in a fixed time horizon that ignored future market movements hence not applicable to multi-period investment horizon. Sharpe (1964), Lintner (1965) and Mossin (1966) separately have been ascribed to establishing the Capital Asset Pricing Model (CAPM) model that was developed from Markowitzs (1959) exposition of the Modern Portfolio Theory (MPT) particularly the mean-variance model. The fundamental theory of the CAPM indicates that there is a linear link involving systematic risk, as measured by beta, and projected share returns (Brewton, 2009). The CAPM model endeavours to illustrate the linkage by applying beta to describe the differences involving the likely proceeds from shares and share portfolios (Laubscher, 2002, p.

Historical events of the US Essay Example | Topics and Well Written Essays - 1250 words

Historical events of the US - Essay Example The conventional Protestant spiritual groups set up religious bases in Asia and Africa, as well as over 450 missions in China by the year 1900.The 20th century started with the US entangled in a severe and bloody war. However, that war is no longer remembered, a war that cost millions of dollars, thousands of lives and displacement of millions. ThePhilippine-American War that was fought between1899 to 1902 resulted in approximately 265,000 human deaths. Thewarassistedthe US establish itself as a military powerhouse in the Pacific regions. While the European powers were engaging themselves in the First World War (WWI), the then president of the US Wilson Woodrow was apprehensive that Germany might take up Haiti and destabilize the pathway leading to the Panama Canal. In order to assert and protect its interest, Wilson sent a few hundred US Marines and Navy men to Haiti. In 1898 and 1899, The US took over Hawaii and obtained the Philippines, Puerto Rico, and some parts of the Pacific I slands. Theexpansionraisedthesignificantquery of if their recently annexed states would be given the American citizens civil rights. HavingwonboththeSpanish-American War and Philippines War symbolized both an addition to earlier expansionist desires and a quick departure from suppositions that had steered American foreign strategy before. Fortheveryfirsttime, the US made significant strategic dedications in the Far East; acquiring regions that had never been planned for statehood, and dedicated itself to law enforcement actions.

State of the U.S. economy for the first half of 2008 Essay Example for Free

State of the U.S. economy for the first half of 2008 Essay In the first half of 2008, four things are pummeling the typical American: the housing bust, the credit crunch, higher fuel and food costs and, most recently, a weakening labor market. The unemployment rate rose to 5. 1% in March, while the private sector lost jobs for the fourth month in a row. Consumer confidence is in a 26-year low. Feeling poorer and with fewer people prepared to lend money, consumers are cutting back. Seeing that consumer spending accounts for 70% of American demand, makes it more difficult for the economy especially when it is coupled with a collapse in the once mighty construction industry. The International Monetary Fund (IMF) now officially predicts an American recession in 2008. (The Economist). For the first time, Federal Reserve Chairman Ben Bernanke conceded that the U. S. economy may slip into recession but said growth should pick up later this year as the impact of interest rate cuts and other emergency steps take root. Bernanke told a congressional panel that the economy appeared to be growing, but warned it could shrink in the first half of 2008 as housing and financial markets remain distressed despite dramatic Fed interest rate cuts and emergency lending (Reuters). Volatility and crisis were the watchwords of the U. S. economy in 2007 buffeted by rising oil prices and the subprime mortgage crisis. Their combined impact stretched into 2008 especially in the first half, slowing economic growth. The impact of these factors was felt in the broader economy undermining both business investment and consumer confidence. The U. S. Chamber of Commerce appears to be more optimistic predicting modest growth averaging about 2% in the first half of the year, an improvement over a weak fourth quarter of 2007. Growth should increase to 2. 5% in the second half, as the housing sector bottoms out. Job growth will continue, albeit at a relatively slow pace-with the unemployment rate rising slightly above 5%. Corporate profits should improve as 2008 progresses and business investment will pick up modestly by the middle of the year. Export growth will continue to brighten the overall economic picture. Inflation will be in the moderate range, making further interest rate reductions less likely as the year progresses (US Chamber of Commerce). As 2008 progressed, many Americans experienced a growing despair as they watched their largest asset- the family home- decline in value. The United States is experiencing its worst housing recession in more than 15 years. Underscoring the breadth of the real estate recession, sales of existing homes fell in 45 states and Washington D. C. and prices dropped in more than half the metro areas it tracks according to the National Association of Realtors. In fact, homes are selling at a price 24% less than year ago as foreclosures continue to increase dramatically at 57% in Southern California. The slide in sales are predicted to persist and prices will likely fall throughout 2008, according to a majority of economists surveyed last month by USA TODAY (Knox). The housing downturn is spreading more broadly through the economy. Employers are shedding jobs, consumer confidence and spending have been shaken, and lenders have pulled back. If not for stronger demand for U. S. goods brought on by a weaker dollar, the economy would be in worse shape. To cushion the effect of the on-going crisis, the Federal Reserve has slashed interest rates, promised more cuts if the economy stays weak and perhaps most importantly sharply reduced the odds of financial-market catastrophe by extending its safety net to investment banks. The Federal Reserve has lowered benchmark interest rates by three percentage points to 2. 25 percent since mid-September to help put a floor under an economy hit hard by a housing slump and credit market turmoil. Bernanke said those rate cuts and other emergency measures to thaw frozen credit markets should promote growth over time. Also, Bernanke staunchly defended the Federal Reserves decision last month to broker JPMorgan Chases (JPM) takeover of investment bank Bear Stearns, (BSC) including approval of a loan backed by $30 billion of Bear Stearns assets. According to Bernanke, â€Å"A Bear Stearns default could have sparked a chaotic unwinding affecting the overall economy. Given exceptional pressures on the global economy and financial system, the damage caused by a potential Bear Stearns default could have been severe and extremely difficult to contain† (Kirchhoff). In retrospect, if the Federal Reserve did not intervene bankruptcy was inevitable which might have caused the U. S. and global markets to collapse. Even though the economy is slowing, inflation, boosted by skyrocketing energy and food prices remains a concern and constraint for the central bank. Another factor would be the declining value of the dollar; if the dollar buys less, inflation rises. The Federal Reserve data show that the U. S. dollar has declined about 10 percent over the past year against a trade-weighted basket of currencies from major U. S. trading partners. Moreover, the dollar sank to new lows against the euro in the days following March 4, 2008 after a series of dour reports on the U. S. economy and expectations that the Federal Reserve will continue slashing interest rates. Indeed, with the falling of the dollar, prices of all the things bought are rising. The Producer Price Index for one month was up 1. 1% in March with the price of wheat and rice up at least 100 percent than last year. The price of oil reached $114 a barrel and gasoline is also at a new high of $3. 38 per gallon. Purchases of crude oil jumped, reflecting increases in the number of barrels bought and a record price surpassing $100 a barrel on the New York Mercantile Exchange early this year. The U. S. is the worlds biggest consumer of crude oil and higher fuel costs are making imports more expensive (Bloomberg). America is in fact the worst food and energy inflation in two decades and consumers take a direct hit. The pace of job losses in America has been relatively mild compared with previous downturns. However, data showed the economy during February shed the biggest amount of jobs in nearly five years. Because of the high fuel prices, budget airlines are bleeding and are filing bankruptcies resulting to further job losses. Frontier airline was the fourth airlines to do so in just two weeks. There is also slow spending in malls everywhere as increasing number of consumers struggling to make ends meet causing retailers such as Sharper image, Levitz Furniture and stores like Ann Taylor, Zales Jeweler and Footlocker to close. General Electric (GE), second largest company on Earth, reported a 6% loss in income for the first quarter. It was a surprise result that rattled Wall Street with the stocks of GE experiencing its worst one-day loss since the 1987 crash. GE had a lot of trouble selling commercial real state and people are not buying appliances. Economic figures indicate a weakening economy. The Energy Information Administration (EIA) forecast that U. S. real gross domestic product would contract from $11. 577 trillion in the fourth quarter of 2007 to $11. 563 trillion in the first quarter of 2008, then decline to $11. 542 trillion in the second quarter. U. S. Stock prices continue to slip, with the blue chip Dow Jones industrial average closing down at the 12,000-level. Prices for U. S. government bonds also fell, as did the value of the dollar. As waves of bad news began to wash in- foreclosures, tumbling dollar, falling retail sales and more recently investment bank rescues- exporters were the only thing keeping the national nose and lips above the recessionary waters. The decline in the value of the dollar relative to other currencies, notably the euro, has helped make U. S. goods less expensive for overseas buyers and therefore more attractive. This fuelled a healthy global demand for U. S. products and services resulting to earnings from exports rising to a new record (Chandra). So what can be done in order to address the crisis? The government should introduce a fiscal stimulus, which would help create new jobs in 2008, and induce consumer spending through tax rebates in order to keep the economy moving. To try and keep the subprime-mortgage crisis from escalating, the Federal Reserve should propose changes for loans including requirements that creditors should strictly verify a prospective borrower’s income and assets before providing actual loans. The government must offer mortgage advice to homebuyers who may not have understood the risks. Often borrowers did not even realize that their monthly payment would rise if interest rates went up. Subprime borrowers on adjustable interest rates, whose mortgages make up just 7% of the total, accounted for more than 40% of the foreclosures begun in the fourth quarter of last year (The Economist). And if the subprime mortgage crisis gets worse, the government should consider a possible bailout for the housing market. For a long-term solution, a new version of a deliberate program to build up the middle class must be instituted similar in nature with postwar programs like the G. I. Bill, interstate highway system and other measures with job-creating investments in biomedical research, alternative energy, roads, railroads and education (McIntyre). The G. I. Bill, created after World War II, was one of America’s most successful investments. According to the 1988 report for Congresss Subcommittee on Education and Health of the Joint Economic Committee by 1952, the US government had spent $14 billion (1952 dollars) on educational and job training benefits for 7. 8 million veterans. Of these funds, $7 billion was spent on college and graduate school for 2. 2 million G. I. ’s. ? The first benefit from this investment was increased growth in the economy. The report calculated that about 40 percent of those who took advantage of the G. I. Bill would not otherwise have been able to attend college. The extra output those people created in the economy amounted to $35. 6 billion (1952 dollars after factoring out inflation) over the next 35 years. America is in the bleak of a recession and a sound economic plan should be in place to cushion its effect. References Chandra, Shobhana. â€Å"U. S. January Trade Deficit Rises 0. 6%; Exports Gain (Update6)†. Bloomberg. 29 April 2008. 29 April 2008. http://www. bloomberg. com/apps/news? pid=20601087refer=homesid=aynvcWrnI 8w. Doggett, Tom. â€Å"UPDATE 2-U. S. economy to contract in 1st half of 2008 –EIA†. Reuters. 11 March 2008. 2 May 2008. http://www. reuters. com/article/oilRpt/idUSN1148909720080311. Kirchhoff, Sue. â€Å"Fed chief Bernanke defends Bear Stearns deal†. USA Today. 4 April 2008. 2 May 2008. http://www. usatoday. com/money/economy/2008-04-02-bernanke economy_N. htm . Knox, Noelle. â€Å"Falling home sales problem spreads to 45 States†. USA Today. 14 Feb 2008. 2 May 2008. http://www. usatoday. com/money/economy/housing/2008-02-14 housing-q4 nar_N. htm. McIntyre, Jamie â€Å"Tenth anniversary of the Gulf War: A look back† CNN. com In-depth specials Gulf War. 16 Jan. 2001. 24 April 2008. http://archives. cnn. com/2001/US/01/16/gulf. anniversary/index. html. MoneyNews. â€Å"Treasury: Economy May Improve in 2nd Half 2008†. MoneyNews . 24 April 2008. 2 May 2008. http://moneynews. newsmax. com/money/archives/articles/2008/4/24/085350. cfm. Subcommittee on Education and Health of the Joint Economic Committee (1988). A Cost Benefit Analysis of Government Investment in Post-Secondary Education Under the World War II GI Bill. The Economist. â€Å"Getting it right on the money†. The Economist. 3 April 2008. 8 April 2008. http://www. economist. com/displaystory. cfm? story_id=10958702. US Chamber of Commerce. â€Å"The Economy in 2008†. US Chamber of Commerce. 2 May 2008.

Calculations of Rare Earth (Y, La and Ce) Diffusivities

Calculations of Rare Earth (Y, La and Ce) Diffusivities First-principles calculations of rare earth (Y, La and Ce) diffusivities in bcc Fe Xueyun Gaoa,b,[*], Huiping Rena, Chunlong Lia,c, Haiyan Wanga, Yunping Jia, Huijie Tan a ABSTRACT: The impurity diffusivities of rare earth elements, Y, La and Ce, in bcc Fe have been investigated by the first-principles calculations within nine-frequency model. The microscopic parameters in the pre-factor and activation energies have been calculated. For the three elements, the first nearest-neighbor solute-vacancy interactions are all attractive, in which Y and La solute atoms more favorably bond to the vacancy. The solute-vacancy binding energy can be explained in terms of the combination of the distortion binding energy and the electronic binding energy, and the decomposition results of the total solute-vacancy binding energy suggest that the strain-relief effect accounts for larger portion of the binding energy for Y and La than that for Ce. The diffusion coefficients of Y are one order of magnitude larger than that of La, and predicted to be comparable to that of Fe self-diffusion. Compared with Y and La, Ce shows large migration energy and small solute-vacancy att ractive interaction, which accounts for the lowest diffusivity of this element. Keywords: Diffusion; Rare earth; Bcc Fe; First-principles calculations 1. Introduction In the past years, the addition of rare earth (RE) elements has been regarded promising in steels. A series of beneficial research for the development of rare earth addition have been focused on the purification and modification of inclusion, since RE elements are characterized by significant negative free energy changes for compound formations [1-3]. RE doping also improve the high-temperature oxidation resistance and the corrosion resistance of steels due to the reactive-element effect (REE) [4,5].In addition, the solidification, phase transformations, recrystallization behavior, of steel can be improved by adding RE [6, 7]. Knowledge of the above mentioned mechanism is essential to understand the influence of RE additions on the physical, chemical and various properties of steels. In spite of the progress so far in RE application, it is apparent that many questions still remain rather controversial. A thorough theoretical study on the diffusivities of RE elements in Fe-based alloy is still lacking, which is essential for understanding the effects of RE on the structure and properties of steel, and is also helpful for designing and preparing RE doped steels [8]. For the three commonly used RE elements, Y, La and Ce, to our knowledge, only the diffusion coefficient of Y has been reported [9]. The diffusion of substitutional-type solute is mainly controlled by vacancy mechanism. In this case, the interaction of solute atom with vacancy plays significant roles in understanding of the diffusion properties of solutes. To understand the microstructure evolution in bcc Fe alloy, DFT method has been applied in calculations of the binding energies of solute atom with vacancy [10]. Based on the nine-frequency model of Le Claire, Ding and Huang et al. [11,12] developed a computational framework to calculate the solute diffusion coefficients in bcc Fe, which presents an effective method in investigation of the diffusion properties in bcc Fe alloy. The purpose of this work is to investigate the impurity diffusivities of rare earth elements, Y, La and Ce, in bcc Fe by the first-principles calculations within nine-frequency model and the semi-empirical corrections for magnetization[11,13], calculate the associated solute-vacancy binding energies, migration energies, pre-factors and activation energies for these impurity diffusivities, as well as the self-diffusion coefficient of Fe, thus discuss the related factors of the diffusion coefficients. 2. Methodology The temperature dependence of diffusion coefficient D is expressed in the Arrhenius form D=D0exp(-Q/kBT), where D0 and Q are the pre-factor and activation energy, respectively. Below the Curie temperature, the self-diffusion and solute diffusion coefficients in bcc Fe deviate downward from the Arrhenius type relationship extrapolated from the paramagnetic state [14]. These deviations are attributed to the change of magnetization which affects the diffusion activation energy. To investigate the effect of magnetic disorder on the diffusion activation energy of spin-polarized metals, Ding et al. [15] reported a first-principles approach based on the spin-wave DFT method for studying the self-diffusion of bcc Fe and fcc Co, and the calculated values of ÃŽÂ ± agree well with the experimental data. More recently, by combination of the first-principle calculations and Heisenberg Monte Carlo simulations, Sandberg et al. [16] presented a quasi-empirical model to study the magnetic contribu tion to the self-diffusion activation energy of bcc Fe. Murali et al. [17] conducted a systematic study of the effects of phonon and electron excitations on the free formation energy of vacancy, the solute-vacancy binding energy, and the vacancy migration energy in bcc Fe. The authors then calculated the Fe self-diffusion coefficient based on the computed free energies, by employing the semi-empirical model presented in Ref. [18]. The diffusion associated data yielded by these methods are in good agreement with experiments. We employ the semi-empirical model to describe the dependence of the diffusion activation energy on the magnetization in the ferromagnetic state [18]: QF(T)=QP[1+ÃŽÂ ±s(T)2] (1) where QP is the activation energy in the paramagnetic state; s(T) is the ratio of the magnetization of bcc Fe at a certain temperature T to that at 0K, and has been experimentally measured [19,20]; the constant ÃŽÂ ± quantifies the extent of the influence of magnetic on activation energy, the measured value of ÃŽÂ ± for Fe self-diffusion is 0.156 [11].In the case of the solute species investigated in this context that have no measured ÃŽÂ ± values available, the values can be estimated from a linear correlation with the induced changes in local magnetization on Fe atoms in the first and second neighbor shells of a solute atom [21]. The first-principles calculations give direct access to the magnitude of the activation energies for self- and solute diffusion in the fully ordered ferromagnetic state (T=0K). Given the values of ÃŽÂ ± and s(T), we can compute QP through the relation , and QF(T) from Eq. (1). We based the diffusion calculations on the assumption that the mechanism of diffusion is primarily monovacancy mediated. The self-diffusion and solute diffusion coefficients on a bcc lattice can be expressed as following [11,22]: Dself=a2f0Cvw0 (2) Dsolute=a2f2Cvw2(-ΆGb/kBT) (3) where a is the bcc lattice constant, f0=0.727 is the self-diffusion correlation factor, f2 is the correlation factor for solute diffusion which depends on the relative vacancy jump frequencies around the solute atom. Cv denotes the equilibrium vacancy concentration, can be written as Cv=exp(ΆSf /kB)exp(-ΆHf /kBT), where ΆSf and ΆHf are the vacancy formation enthalpy and entropy, respectively, the harmonic approximation makes these two become temperature-independent constants. and kB is Boltzmanns constant. w0 and w2 are the vacancy hopping frequencies for Fe and solute atoms to exchange with a nearest-neighbor vacancy, respectively. Based on transition state theory (TST), the vacancy hopping frequency w is written as , where and are the phonon frequencies in the initial state and transition state, and the product in the denominator ignores the unstable mode; ΆHmig is the migration energy, gives the energy difference for the diffusin g atom located at its initial equilibrium lattice position and the saddle-point position. The solute-vacancy binding free energy ΆGb can be expressed as ΆGb =ΆHbTΆSb, where ΆHb and ΆSb are the binding enthalpy and entropy, respectively. The correlation factor f2 can be calculated using the nine-frequency model developed by Le Claire [13] which involves different jump frequencies of vacancies to their first neighbor position in the presence of the solute atoms, as illustrated in Fig. 1. In this model, the interaction of solute-vacancy is assumed up to second neighbor distance. The nine frequencies shown in Fig. 1 illustrate all of the distinct vacancy jumps in a bcc system with a dilute solute concentration, including the host Fe atom jump w0 without impurity. The detailed calculation procedures could be found in Ref. [11]. Fig. 1. Schematic illustration of the nine-frequency model for the bcc Fe crystalline with a solute atom. The arrows denote the jump directions of the vacancy. The numbers in the circle represent the neighboring site of the solute atom. For convenience, we can represent the self- and solute diffusion equations (Eqs.(2) and (3)) in Arrhenius form to obtain the pre-factor and activation energy of diffusion. By combining the above Eqs., the diffusion coefficient for Fe self-diffusion and solute diffusion can be expressed as: (4) For self-diffusion, the pre-factor is, and the activation energy given as . Also, the solute diffusion coefficient can be expressed in an Arrhenius form with the pre-factor is, and. The first-principles calculations presented here are carried out using the Vienna Ab initio Simulation Package(VASP) with the projector augmented wave(PAW) method and the generalized gradient approximation of Perdew-Burke-Ernzerhof functional(GGA-PBE) [23]. All calculations were performed in spin polarized. The computations performed within a 4à ¯Ã¢â‚¬Å¡Ã‚ ´4à ¯Ã¢â‚¬Å¡Ã‚ ´4 supercell including 128 atoms. The binding, vacancy formation and migration energies were calculated with 300eV plane-wave cutoff and 12à ¯Ã¢â‚¬Å¡Ã‚ ´12à ¯Ã¢â‚¬Å¡Ã‚ ´12 k-point meshes. The residual atomic forces in the relaxed configurations were lower than 0.01eV/Ã…. The transition states with the saddle point along the minimum energy diffusion path for vacancy migration were determined using nudged elastic band (NEB) method [24] as implemented in VASP. We adopt the harmonic approximation (HA) to consider the contribution of normal phonon frequencies to free energy. The normal phonon frequencies were calcu lated using the direct force-constant approach as implemented in the Alloy Theoretic Automated Toolkit (ATAT) [25] package. Similar cutoff energy, k-point mesh size and supercell size used for the total energies were used for the vibrational calculations. 3. Result and discussion Table 1 illustrates our calculated energies for vacancy formation, migration and binding, as well as the constant ÃŽÂ ± for solute species, the associated paramagnetic activation energies and fully ordered ferromagnetic activation energies for both self- and solute-diffusion. For pure bcc Fe, the vacancy formation energy and migration energy obtained here are consistent with the reported range of values, ΆHf=2.16-2.23 eV and ΆHmig=0.55-0.64 eV [11,26,27]. For Y impurity in bcc Fe, the calculated vacancy binding energy in full ordered ferromagnetic state also compare well with the previous first principles work [28], in which ΆHb=-0.73 eV. It can be seen that Y and La have smaller activation energy than that for Fe self-diffusion, while Ce is predicted to have a lager value of activation energy than that for Fe self-diffusion, in both the ordered ferromagnetic and paramagnetic state. Table 1 Vacancy formation energy ΆHf , solute-vacancy binding energy ΆHb, migration energy ΆHmig, the ferromagnetic activation energy and the paramagnetic activation energy QP; the variable dependence parameter of activation energy on magnetization ÃŽÂ ±. Fe Y La Ce ΆHf(eV) 2.31 à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ ΆHb (eV) à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ -0.69 -0.66 -0.43 ΆHmig (eV) 0.54 0.09 0.17 1.09 ÃŽÂ ± 0.156 0.088 0.038 0.125 (eV) 2.85 1.71 1.82 2.97 QP (eV) 2.47 1.57 1.75 2.64 Solute-vacancy binding energy plays a crucial role in understanding solute diffusion kinetics. Table 2 presents the binding energies of Y, La and Ce atoms with vacancy in their 1nn, 2nn and 3nn coordinate shells. From Table 2 it can be seen that referring to the first nearest-neighbor solute-vacancy pairs, the binding energies are all negative, which implies the solute-vacancy pairs are favorable. Specifically, Y and La impurities are computed to have higher values of solute-vacancy binding energies -0.69 eV and -0.66 eV in 1nn configuration, respectively, while that for Ce is -0.43 eV. Correspondingly, we found that Y, La and Ce atoms relax towards the 1nn vacancy by 22.3%, 19.6% and 12.2% of the initial 1nn distance (2.488 Ã…) after the structure optimization. The interactions of the solute-vacancy pair at the 2nn shells tend to be smaller in magnitude than that of 1nn, and that of Ce-vacancy predicted to be repulsive. The interactions of the 3nn solute-vacancy are relatively we ak, indicating that the interactions of the solute-vacancy are local. According to Le Clair model [13], in the situation that the interactions of the first and second nearest solute-vacancy neighbors are appreciable, the nine different jump frequencies should be considered. To obtain information on the origin of these attractive behaviors, we decompose the total binding energy into the distortion binding energyand the electronic binding energy as [29] . The distortion binding energy can be obtained by the distortion reducing of the bcc Fe matrix when a solute atom and a vacancy combine to form a solute-vacancy pair, and can be expressed as: (5) where and can be calculated as follows: after the supercell containing a solute-vacancy pair (or a substitutional atom) has been fully relaxed, the solute-vacancy pair (or the substitutional atom) is removed from the system, then the total energy can be calculated. denotes the total energy of the pure bcc Fe supercell, and denotes the total energy of the supercell containing a vacancy. Then can be calculated from . The calculated solute-vacancy binding energies of 1nn, 2nn and 3nn are shown in Table 2, along with the energy decomposition for 1nn solute-vacancy binding. The distortion energies (-0.31 to -0.65 eV) for all solute elements(Y, La and Ce) are negative, and much bigger than their corresponding electronic binding energies (-0.04 to -0.12 eV). This implies that the distortion energy accounts for a major part of the total solute-vacancy binding energy, i.e. the strain relief effect contributes significantly to the interaction between the impurity atom and the vacancy, esp ecially for the solute Y and La, which accounted for 94.2% and 97.0% of the total binding energy, respectively. Furthermore, there is a strong correlation between the binding energy and the distance of the solute-vacancy, and the lattice relaxation around the vacancy is local. For the case of Ce-vacancy , specifically, we found that Ce atom relax away from the 2nn vacancy by 4.3% of the initial 2nn distance, which leads to the positive binding energy. Table 2 Decomposition of the total solute-vacancy binding energy into distortion binding energy and electronic binding energy. Units are eV. Solute element Y La Ce ΆHb (1nn) -0.69 -0.66 -0.43 (1nn) -0.65 -0.64 -0.31 (1nn) -0.04 -0.02 -0.12 ΆHb (2nn) -0.16 -0.21 0.10 ΆHb (3nn) -0.06 0.09 -0.05 The calculated migration energies of the different vacancy jumps corresponding to the paths in Fig. 1 are listed in Table 3. The migration energies of w2 jump for Y and La are lower than that of w0 jump for host Fe atom (0.54 eV), while the migration barrier of Ce in bcc Fe is higher than that of Fe self-diffusion. The migration barrier of w2 jump for Y is 0.09 eV, comparable to the reported value of 0.03 eV and 0.02 eV [9, 30]. The results indicate that there is a correlation between the binding energy of solute-vacancy and the migration energy, i.e. the strong attraction of solute-vacancy in 1nn configuration gives rise the low migration energy of the corresponding vacancy jump. For the three solute atoms, because of the strong attraction of 1nn solute-vacancy, the migration barriers of which the 1nn vacancy jump away from the solute atom, i.e. w3, w3, and w3, are higher than that of the opposite jumps, i.e. w4, w4, and w4, as well as that of Fe self-diffusion in pure bcc Fe. And t he same tendency can be found in the results of jump w5 and w6. Table 3 Migration energies for different jumps in the presence of Y, La and Ce in bcc Fe matrix. Units are eV. Jump Y La Ce w2 0.09 0.17 1.08 w3 1.81 1.84 1.55 w4 0.91 0.99 0.92 w3 0.93 1.23 1.07 w4 0.04 0.03 0.08 w3 0.86 0.92 0.87 w4 0.12 0.05 0.11 w5 0.94 0.98 0.89 w6 0.69 0.67 0.82 The correlation factor f2 is related to the probability of the reverse jump of a solute atom to its previous position [31]. Table 4 lists the calculated values of correlation factors for Y, La and Ce at representative temperatures of 850, 1000 and 1150K. The correlation factor of Y is 3.3ÃÆ'-10-5 at 1000K, close to the value of 1ÃÆ'-106 obtained by Murali [9]. For the three elements, the correlation factors of Ce have the highest values, and the correlation factors of La are one order of magnitude lower than that of Y. Therefore, Ce atom is the most difficult to return back to its original position in the temperature range of our investigation. Including the smallest binding energy, highest migration energy and correlation factor, provides an explanation for the low diffusivity of Ce atom. Table 4 Correlation factors (f2) for Y, La and Ce solute-diffusion at representative temperatures of 850, 1000 and 1150K. T(K) Y La Ce f2 f2/ f0 f2 f2/ f0 f2 f2/ f0 850 6.4ÃÆ'-106 1.111 2.9ÃÆ'-107 1.264 0.379 1.373 1000 3.3ÃÆ'-10-5 1.070 2.4ÃÆ'-106 1.223 0.381 1.370 1150 1.2ÃÆ'-104 1.034 1.4ÃÆ'-10-5 1.188 0.383 1.367 Table 5 lists the calculated diffusion activation energies and pre-factors for Fe self-diffusion and Y, La and Ce impurity diffusion. For pure bcc Fe, we find our calculated results are in good agreement with the published values. For Y impurity in bcc Fe, the calculated activation energy in full ordered ferromagnetic state is lower than the previous first principles work, and the pre-factor is as much as two orders of magnitude lager than the reported value. The experimental or calculated diffusion coefficients of La and Ce are not available to the best of our knowledge. For the case of experimental investigation, due to the very small solubilities of La and Ce in iron, the measured data may be affected by segregation of solutes, grain boundary, other impurities and the method of detection. Besides, the theory calculations, e.g. molecular dynamics (MD), first-principles etc. have not been applied widely in the study of RE contained steel yet, so the fundamental data of RE elements i n iron, such as the potential functions of Fe-La and Fe-Ce, is lacking. Table 5 Activation energies in the fully ordered ferromagnetic state () and paramagnetic state (QP), along with diffusion pre-factors for Fe self-diffusion and impurity diffusion of Y, La and Ce in bcc Fe. Reference (kJ mol-1) QP(kJ mol-1) D0(m2/s) Fe Present work 275.3 238.1 2.99ÃÆ'-10-5 Huang et al. [11] 277 239 6.7ÃÆ'-10-5 Nitta et al. [32] 289.7 ±5.1 250.6 ±3.8 2.76ÃÆ'-10-4 Seeger[33] 280.7 242.8 6.0ÃÆ'-10-4 Y Present work 165.9 159.9 1.09ÃÆ'-109 Murali et al. [9] 218.1 à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ 8.0ÃÆ'-107 La Present work 175.6 169.2 2.88ÃÆ'-1010 Ce Present work 286.3 275.8 7.66ÃÆ'-106 Fig. 2 presents a direct comparison between the calculated and published temperature dependent diffusion coefficients for Fe self-diffusion and Y solute diffusion. For Fe self-diffusion, the calculated values are in good agreement with Huang et al. [11] and Nitta et al. [29], but smaller than the measured d