The Daily Telegraph

For my coursework piece, I decided to a newspaper editorial which had been published online. The piece was written as if it had been published in The Daily Telegraph, a right-wing middle class newspaper. I chose to do the piece because I am interested in current affairs and newspapers, and I am a very opinionated person. I thought that a newspaper column would be a good place to share my opinion on the topical story of waterboarding. For my style model, I went onto the Telegraph's website and found a newspaper column by Boris Johnson, the Conservative Mayor of London. As a Conservative, his column had a slight anti-Labour bias, although it was very subtle and often humorous. I attempted to replicate this when I mentioned that waterboarding is classed as an ‘enhanced interrogation technique' and quickly quipped that that was â€Å"more spin in one phrase than Alaistair Campbell managed in an entire dossier† – a reference to the controversial September Dossier which ‘sexed up' claims that Iraq had Weapons of Mass Destruction. From that quote, we can see some of the writer's persona, seeing immediately that they are critical of the Iraq War, despite later making it clear he is a Conservative (â€Å"thankfully, I'm a son of Thatcher†). We can see more of the writer's persona throughout, by writing with a high register, we see that they are quite sophisticated and maybe slightly arrogant. The piece starts with a graphic description of what would happen to a victim of waterboarding, but as it features direct address, it makes the reader feel like that it is happening to them – â€Å"you have a bag over your head†, â€Å"you are shackled†, â€Å"you feel like you are drowning†. After each description of the torture, the actual theme is introduced. Originally, my piece was going to follow a structure by which each waterboarding scenario would be followed by the writer's opinion, but before my final draft I decided that this actually distracted from the main point of the article, so I decided not to continue with this idea. My main argument starts in the paragraph beginning â€Å"Let's be clear on this matter†. That sentence of â€Å"let us be clear† makes it seem like I know what I am talking about and that I am being completely honest. My arguments are further bolstered by listing officials who have disagreed with George Bush's claims, such as the Director of Public Prosecutions and the United Nations High Commissioner on Human Rights. The summing up of my arguments begins with George Bush's original comment which sparked this news story. The language used in the ensuing four paragraphs is emotive, and reads almost as if it were a speech. It really attempts to put the reader on the side of writer, and make them believe that Bush was completely out of order. The story was published on the week on which Remembrance Day fell, so I as the writer incorporated this to try and shock the reader and make them nod sagely in agreement with me when I state that the reason we entered the Word Wars in the first place was to â€Å"fight for our lives and our rights†, and then contrasting that by saying that Bush â€Å"a former leader of the free world† can say that â€Å"freedom and democracy†¦ can go to pot if it might save some lives†. The following one clause sentences have a short and long lasting impact by simply refuting Bush's claims. I enjoyed writing this piece, as it gave me a chance to put my opinions forward. Having my peers read my work and give feedback was a good experience that I enjoyed, as I like people correcting me and reading my work.

Origin of the Internet Essay

The Internet as we know it originates from government-funded research into networking technologies with strategic applications. Journalist and erstwhile Internet historian David Hudson (14-16) observes that the ARPANET or Advanced Research Projects Agency Network formed the technical backbone of what would become the Internet. The ARPANET was a communications network in which each node had equal network privileges. The rationale behind this decentralized architecture was that regardless of which node on the network would be destroyed, the network’s functionality would not be compromised. This is perhaps what distinguishes the Internet most from other communications technologies, and is possible due to the development of packet switching and TCP/IP which enabled data to be sent discontinuously to circumvent the need for a dedicated data stream. However, it was not until the ARPANET was interlinked with the NSFNet in the mid-70s that the term â€Å"Internet† began to attain increasing currency among network professionals. Furthermore, the increasing adoption by other nations as well as universities and research institutions of TCP/IP permitted the expansion of the ARPANET’s fundamental architecture, effectively increasing the geographical coverage of the emerging network. (National Science Foundation 10-12) What truly permitted the Internet to integrate itself into the lives of individuals beyond government and research was the rise of several applications and protocols that increased its ‘extracurricular’ potential, most notably hypertext. Hypertext within a computer networking context was developed by CERN’s Tim Berners-Lee but was made ubiquitous by Marc Andreessen’s Mosaic browser, which was the first web browser to gain mass acceptance. Since then, the Web has become the popular face of the Internet. Works Cited Hudson, David. Rewired. Indianapolis, Indiana: MacMillan Technical Publishing, 1997. Aboba, Bernard. The Online User’s Encyclopedia: Bulletin Boards and Beyond. Massachusetts: Addison-Wesley Professional, 1994. National Science Foundation. America’s Investment in the Future, The Internet: Changing the Way We Communicate. Retrieved October 30, 2008 from: http://www. nsf. gov/about/history/nsf0050/pdf/internet. pdf

Qualitative analysis Essay Example | Topics and Well Written Essays - 1500 words

Qualitative analysis - Essay Example Through qualitative research, the group will be able to establish the characteristic that stands out among the members of the population hence this may be concluded as the behaviour of the population members. NOTE: The characteristics (qualities) could be behaviour, habits, grades, depending on the qualities the group will base their research on., qualitative research will be of great importance to the general public, like to businessman, they can easily learn the preferences of their customers, to politicians, they can learn the expectations of the general public in terms of leadership and sometimes even managers can learn the attitude of their workers towards them. Through the different groups of people learning about what others think, expect and want ,the general public will be able to benefit by having different leaders, like politicians keeping to the expectations of the general public thus better running of public affairs. Also businessmen will keep to the standards that their customers expect among other benefits. The data to be collected is mainly primary data and the group will mainly collect their data through interviews which will be audiotape thus this interviews could be conducted by visiting the sites of the survey or through radio and also through telephone calls. The group is to study the different... a to be collected is mainly primary data and the group will mainly collect their data through interviews which will be audiotape thus this interviews could be conducted by visiting the sites of the survey or through radio and also through telephone calls. The group is to study the different qualities of the population and they might identify outstanding practices in their study and also learn why the population has to practice certain characteristics in relation to the qualities identified. This research is to be carried out by the focus group in a site of their own choice where they find suitable depending on the qualities they would like to study, in relation to the population of their choice. METHODS OF ANALYSIS Qualitative data can mainly be analyzed by describing data using: i) Numerical methods and ii) Graphical methods. Numerical analysis: The data could be classified into Classes: This is where data in the audiotapes is categorised in relation to the different qualities being studied. (Data is grouped into: Class frequency: The number of observations in the data set falling in a particular class grouped together. Class relative frequency: The class frequency divided by the total number of observations in the data set. Through these descriptions, qualitative data can be analysed in a table such as the one shown below: Behaviour (class) No. of individuals (frequency) Relative frequency (proportion) Kind Rude polite 5 7 10 0.227 0.318 0.455 Totals 22 1.000 Advantages: i. One is able to get an overview of the data clearly in one glance. ii. We can easily determine the number of different individual that full under each quality. iii. The total number of the population of study can be easily determined and also the proportions. iv. They are easy to

Strategic Human Resources Planning for Hilton Hotel Research Paper

Strategic Human Resources Planning for Hilton Hotel - Research Paper Example It helps to identify the problems and issues which impacts on the organization and determine its competitive position in the industry. Strengths The strength of the company lies in its vast international presence. The main presence of the company is felt in Europe and USA. However, its operations are spread across almost all nations including China, India, Japan, Germany etc. One of the main strengths of the hotel is that it is well diversified in terms of the services it offers. Its services range from high-end services to middle and low-end product mix (Hilton Hotels and Resorts, 2011). Moreover, it also possesses the additional strength of having solid integration features, such as having ownership of companies which manufactures products and furniture for the company or even invests in its online travel reservation enterprises (Hilton Hotels and Resorts, 2011). Weaknesses The hotel was greatly impacted by the economic and financial downturn. It remains highly vulnerable to the do wnturn happening in the global economy or other catastrophes which could limit its global operations. The financial downturn was one of the main reasons why Hilton Hotels was caused to move headquarters to the D. C. Area with the aim to cut down costs. This has also resulted in high employee turnovers in the organization (Rosenwald, 2009). The Hilton hotel in the USA can also be vulnerable to the worker’s strikes and cracking down on the undocumented workers in the country. This is because the majority of the holdings of the organization are based in the US. Opportunities The quick technology changes and changing landscape has been enhancing demands for hotels in the world. Consumer demands rise having to push forth for the growth of hotels which appears as a favorable opportunity for the organization to explore. According to the Smith Travel Research (STR), the USA hotels are projected to see an increase in the performance indicators in terms of occupancy and average daily r ates. Occupancy rates were projected to be 58.5% in 2011 while average daily rates are projected to be increased from 4.2% to the US $102.21. The following figure would reflect the occupancy rates and the ADR rate increases since 2004 till 2011 (Travel Media Group, 2011). Figure 1: Occupancy Rates, 2004-2011 (Source: Travel Media Group, 2011) Figure 2: ADR (Source: Travel Media Group, 2011) With the growth of the emerging markets the company could its resources to tap them. This is especially applicable to the business class and the middle prices markets in the hotel industry. Moreover, there has been an increase in attractiveness of features like spas, gaming activities, games for kids and various other features. Apart from that consumers also look for the eco-friendly atmosphere which Hilton hotels could incorporate in order to add to unique features (Travel Media Group, 2011). Threats There is tremendous competition in the hotel industry with the entry of new firms in both the US A and also other nations. This could be a matter of a threat to the company and it would have to strengthen its base to fight against this competition. Also, the changing tastes of consumers can be a challenge before the organization. There would also be diversity among competitors in terms of price strategies, product differentiation strategies, service management etc.

The Important of Simulations Assignment Example | Topics and Well Written Essays - 500 words

The Important of Simulations - Assignment Example They only need to be totally within the computer environment to play any game. Another interesting part of simulation is how the whole concept works. It is hard to believe that something good can come out of mimicking. However, this is made to look more serious where one earns that simulation is not about imitation alone (Pidd, 2003). 2-In the case of any decision making type, the makers of the decisions will have to understand, plan, analyse as well as manage the system. These activities are involved in decision making. Typically, the decisions involve real systems comprised of complex methods with highly interdependent components that exhibit vulnerability as well as change over time. With the absence of a model, makers of decisions would make use of various processes for information gathering from a system that is real, process it and finally select an action which creates some change within the system. In general, model based decision making as well as simulation based decision making particularly do offer decision makers a way of investigating the system’s representation, use alternatives to experiment and then predict the proposed changes effects, that are external to the system. The approach does increase the decision space greatly. This means that it allows for the evaluation of many alternatives. The approach is not invasive on the system and allow for the assessment of risk of actions. For a decision maker to directly interact with simulation models effectively, models require to be entrenched in decision support systems, which enable data entering within the model as well as enhance the model’s output presentation (Pidd, 2003). 3-Some highly complex operations that benefit from simulation include transportation of raw material. Trains or truck, which transport finished goods or raw materials are scheduled as well as planned on the simulation basis. The

Chapter 9 A and B Essay Example | Topics and Well Written Essays - 1250 words

Chapter 9 A and B - Essay Example However, there was a remarkable transformation after the 1960’s. For example, Japan turned its World War II defeat into a stepping stone for postwar economic success (East Asia 368). In the years that followed, Japan experienced economic growth that was above that of china. Consequently, it was considered an economic engine for the world and even rivaled the United States economy. On the other hand, after 1972 china started to experience economic success. This was after it opened doors for bilateral talks with the United States. Currently, East Asia act as the most active region in the global economy, it is changing the world in different ways. On the other hand, East Asia is mainly composed of mainland in terms of total land area. However, the role played by islands and its people in forging realms regional geography has been tremendous. This region has also been dominated by conflicts of water between the mainland and the islands (East Asia 369). In fact, the Japanese and Ch inese have been arguing over the ownership of islands in these waters. This is because of the vast oil deposits and the fishing grounds. Sometimes china is referred to as being East Asia. This is because it is the prominent country in this area in terms of population and has played a massive role in the world affairs (East Asia 369). However, there are other political entities in the East Asia. They include Japan, South Korea, North Korea, Mongolia, and Taiwan (East Asia 369). However, Taiwan is referred as part of china while North Korea is viewed as a failed state. China has been defined by the four famous rivers system. This is in together with their basins, valleys, deltas, and estuaries. However, the most notable are the Huang He. This makes a large loop around the Ordos Desert and then flows into Bohai Gulf, and the Yangzi River (East Asia 372). This river with its tributaries forms the source of water ideal for most of the activities in the capital of china. There is also Yan gzi River in the Chang Basin in china. These two rivers originate in the snowy mountains of the Qing-Hai-Xizang Plateau (East Asia 372). The other two rivers have a shorter distance. However, one of the rivers (Xi River) forms an estuary that acts as the greatest center for China globalization. Additionally, there is another river known as Liao. China, for a long time, has been controlled by dynasties. At these dynasties, China area continued to expand and at the same time decreasing. On the other hand, China had Qing Empire as the largest. However, the empire became weak at its final stage. This is because it was confronted by the imperial powers such as Europeans, Russians, and Japanese (East Asia 376). The collapse of China Empire paved way for the revolutionary China and charismatic leader named Sun Yat-sen led this (East Asia 377). The nationalistic blamed the authorities for China woes. Consequently, they attacked the emperor’s garrison all over China, and this resulted in the fall of Qing Dynasty (East Asia 378). This was followed by the formation of China Communist. Initially, the nationalist cooperated with the imperial authority. However, after Chiang Kai-shek rise to power, all the foreigners fled China. On the other hand, Japan has played a significant historical role in East Asia. Since the seventeen century, Japan policy was on isolation. In fact, contact with the outside world was of a limited nature. However, the Meiji Restoration dropped the policy. This regime

The Picture of Dorian Gray Essay Example | Topics and Well Written Essays - 1750 words

The Picture of Dorian Gray - Essay Example For Dorian, the appearance of beauty is all that matters, and many characters in the novel judge him solely on his looks, rather than his actions. It is the worship of youth and beauty for beauty's sake that leads to Dorian down the path of hedonism and from there to the embrace of sin. Early in the novel, Dorian is a somewhat innocent character, and the artist, Basil Hallward, feels protective toward the young man, and does not want others to intrude on their friendship, especially the cynical Lord Henry. The boy has had such a profound effect on Hallward's soul that it has influenced all his work, and he tells Lord Henry, "He is all my art to me now" (Wilde 11). To Hallward, Dorian's looks do reflect something beyond youth and beauty, an admirable personality. But once Dorian begins to associate with Lord Henry Wottan, he learns a new way of expressing himself. Lord Henry likes to play with the idea of morality, teaching Dorian that "the only way to get rid of a temptation is to yield to it" (Wilde 21). In this, he is beginning to lead Dorian down a path of selfish immorality, one where he may do whatever he likes without consequence. He explains the route of hedonism, beginning by convincing Dorian that "youth is the one thing worth having" (Wilde 24), that beauty is more important than thought (Wilde 25), and that his life will be completely worthless without these two qualities. He also explains, "Nothing can sure the soul but the senses, just as nothing can cure the senses but the soul" (Wilde 23), and Dorian, unfortunately, takes to heart only the first part of this maxim. Where Lord Henry's philosophy allows the beautiful young man to become a hedonist, it does acknowledge the importance of the soul, but Dorian doesn't understand this. As Martin Fido succinctly puts it, "Dorian's delight in his own beauty and youthleads him to place the stimulation of the senses through exotic beauty above every other value. This leads to his appalling corruptions" (Fido 85). Oscar Wilde was familiar with the aesthetics of both Hallward and Henry. As an artist, he was familiar with the ideal of beauty for beauty's sake, and he discusses this in his preface, where he explains the role of the artist as "the creator of beautiful things" (xxiii) and also that seeing beauty in beautiful things is the only way to be cultivated. However, we also see Henry's amorality in this preface, when Wilde dismisses the idea of morality or immorality in art (Wilde xxiii). Wilde must have examined this idea from many angles, due to the world he lived in. As he was writing The Picture of Dorian Gray, the culture he lived in was busy condemning his own behavior as immoral. Since he believed "his literary and social standing would protect him" (Nunokawa 12) from persecution, he became less discreet about his relationships with other men even as the English parliament was passing laws again homosexuality, and eventually he was convicted of being gay, and sentenced to two years of hard labor for this crime (Nunokawa 12). If Wilde had instead remained secretive about his actions, he

Argument paper -- Obamacare Essay Example | Topics and Well Written Essays - 1500 words

Argument paper -- Obamacare - Essay Example However, Obama care is not a good option in our society at this moment due the cost involved, biases and high operating costs (Fact 1). Despite its help towards average earners in the American society, it has created havoc and high operational costs to the rich and big businesses. The Obama care affects the American negatively by increasing taxes, causing unfairness in society, straining the economy and changing the cost of operating businesses. First, for the government to get funds to insure millions of American citizens, obviously the money has to come from taxes. Moreover, this can negatively affect the high-income earners thus causing bias in the society. Because of high taxation rates on the rich people, this can in turn affect their employees as a result of the reduction of working hours. The Obamacare is not a good solution, as it seems to be a punishment towards the rich people and big businesses (Investors Business Daily 1). Moreover, due to high taxation on rich businesses might lower the investors confidence, and this might negatively affect the local economy. Another negative situation on the Obama care is its ultimatums towards all American citizens. This law is forceful in that it requires that by January 2014 everybody was to have registered in this programme and those who fail a fee was to apply. Additionally, this Medicaid can only be achieved through the State and the federal funding. Unfortunately, not all states have the capability of fully funding this plan (Obama care facts 1). Thus, about 5.7 million people from the poor backgrounds will be without an insurance cover exposing their lives to danger. Furthermore, the state and the federal governments also provide fund for the plan making matters even more badly. A classic example is the Children Health Insurance Fund (CHIP). As a result, the operation cost of health insurance gets higher than the growth of the economy. This phenomenon strains the available resources in

Investment between China and Africa Essay Example | Topics and Well Written Essays - 2000 words

Investment between China and Africa - Essay Example The researcher states that many studies have shown that China is currently the major destination of foreign direct investment from many parts of the world. However, Chinese have also been aggressive in making investments in other foreign countries with African region being their major target. Just like many other developed countries, China has been engaged in a vicious competition with other countries like the USA and other developed European countries like the United Kingdom in the scramble for resources in Africa. This has been attributed by the fact that Africa is currently the leading continent with so much untapped potential that includes unexploited natural resources and availability of abundant business opportunities resulting from the undeveloped nature of most of its countries. This has made governments of various states apply different strategies in order to have at least a significant pie in these developing economies, one being creating good relationships. China is one of the giant economies in the world today has been applying all means possible in luring African countries to enter into treaties and good business relations, a factor that has made some of the major Chinese companies establish their operations in Africa. Some studies have shown that China is the leading bilateral trade partner with Africa, a two-way trade that has dramatically been growing in the past two decades through the major growth has experienced in the last one decade. In the year 2011, the bilateral trade between China and Africa is estimated to be over US$166 billion from US$10.6 billion in the year 2000. This growth can only be termed as incredible and is likely to grow at an even higher rate in the coming years.

Dance Paper Essay Example for Free

Dance Paper Essay This dance is danced to live music with traditional Cambodian instruments. There is also singing done by the musicians. It is performed on an indoor stage. The dancers are very graceful and move slowly. The focus a lot on head movements even though there is a slight tilt from side to side. The dancers are carrying a goblet. They wear costumes with headpieces. The hands and wrist move and the focus is on the upper body because the long skirts cover up the legs. This dance looks like it may symbolize something that has to do with the goblet prop. Royal Ballet of Cambodia. This dance is danced on stage and with live music and traditional singing. The dancers are very graceful and the women play both the male and female part. There are dancers in the background sitting. The dancers use their hands and do not travel very much. The costumes are elaborate and the headpieces are very large. The facial expressions are subtle and not dramatic. The torso remains upright. The dance is performed indoors on a stage with lighting. This dance may symbolize a love story because there are both male and female roles. Tahiti Group Dance Performance This dance is performed on an outdoor stage with live music. The male dancers wear grass skirts just as the female dancers. The dance is very fast and upbeat. The female dancers move their hips while the male dancers move their legs in a scissor motion. Like the Cambodian dances, the facial expressions are not dramatic- they are very subtle. Male Tahitian Dance This is performed outdoors on grass to live music. The audience is not shown in this video but it seems like the audience is very casual. The dancers are scream and chant with passion. The male dancers wear garlands around their arms and ankles. They are in very short grass skirts. The dancers move very quickly using their legs and arms. They travel as a group and do the same movements as a group. Fiji Dance This dance is performed outdoors to live music and live singing. This dance is about the Fiji ancestors. The dancers wearing grass garlands around their arms and grass skirts. The singing is very beautiful and the dancers are fluid in their movements. This seems to be a production because there are many dancers. It seems like a very large ceremony. There are different parts to this dance and it goes from smooth and fluid to a part that is more warrior-like. The males march and carry props like they are in battle. In the battle scene, they have their face painted to create a bigger effect of battle. The scene after the battle has the female dancers who are wearing dresses. They dance very fluidly with the paddle prop. It seems like the male dancers bring the strength to the dance and the female dancers bring the grace. Maori- Dances of Life excerpt The dancers provide their own music using their voices and slaps. This seems like it is a warrior dance because the male dancers are very intense. They have painted faces and their faces are dramatic. The dance is about frightening the enemy and getting ready for war. They are dressed in loin cloths and use a spear prop. They dance outdoors in front of an audience. The dance itself has a lot of stomping and moving of the arms. New Zealand- Haka They are dressed in military outfits on the streets. It looks a lot like the Maori dance because they are chanting and using their legs in a squatting motion. They mostly dance with their upper body by moving their arms. It is very dramatic because of the chanting. They are honoring a member of the military who has passed away.

Importance Of Soil Conservation Environmental Sciences Essay

Importance Of Soil Conservation Environmental Sciences Essay Quantitative determination of the extent and impact of soil erosion by water in the tropics have been sketchy. However all available evidence indicates that accelerated erosion is a problem of serious magnitude and with a multitude of negative effects in many tropical countries. The awareness to conserve soil began approximately nine thousand years ago when human civilization shifted from nomadic hunting and gathering experience to a more permanent, settled and intensive soil-dependent plant and animal farming systems (Miller, Rasmussen and Meyer, 1985). Soil provides the medium from which most of the sustenance for humankind is derived. This thin, complex, crustal carpet uniquely integrates many attributes of the lithosphere, atomosphere, hydrosphere and biosphere (Miller, Rasmussen and Meyer 1985). Soil is regarded as a nonrenewable source since its formation from the parent rock material to an agriculturally productive growth medium is a very slow process (Lal 1990). The top soil is where most of the living activities of both flora and fauna take place. According to Brady and Weil 1999, the top soil is the upper most part of the soil ordinarily moved in tillage or its equivalent in uncultivated soils which range in depth from 7 to 25 cm (the plow layer). Removal of this plant nutrient enriched topsoil due to soil erosion would result in lowering of soil fertility through losses of both organic matter and nutrients which would result in decline of crop yields (Lal 1986; Rose and Dalal 1988). This loss in soil productivity due to erosion is serious in caribbean countries where fertilizer substitute for the lost plant nutrients is not affordable. This would lead to poorer soil profile characteristics such as low organic matter levels (Rose 1989;Rose 1998). Soil Erosion is perhaps the most serious form of land degradation throughout the world. For the tropics specifically, while it is acknowledged that erosion is more serious than else where, no analytical or systematic studies have been undertaken to document the problem, it consequences or potential solutions. Soil erosion results in lost water and plant nutrients at rates even greater than those occurring naturally through leaching ( Brady and Weil 1999). If there are no conservation practices present, soil erosion will occur and land degradation, reduced productivity due to loos of top soil, increased runoff and off site sedimentation problems (such as siltation of bodies of water and damage to crops and roads) will occur. The consequent socio-economic costs of sometimes more obvious off site damage are commonly easier to identify and quantify (Chrisholm 1987; Rose 1993). 1.2 Soil Conservation Strategies The caribbean is characterized by steep slopes. The degrees of steepness and the proportion of the land area classified as steep may vary. In Trinidad and Tobago, a larger propotion of steep slopes is still covered with natural vegetation which reduces the soil washed off the surface. Trinidad is marked with a long dry season in the early part of the year and then followed by an intense wet season. Most erosion occurs when the land is cleared of vegetation for farming. This usually occurs just before the rainy season. It is important to note however that most food crop production in Trinidad as well as the rest of the Caribbean, is carried out by small farmers on sloping land with no attention to soil conservation practices. This is the main reason for severe soil erosion in Trinidad and Tobago and by extension the Caribbean. Soil conservation is understood as not only involving the control of loss of soil material due to erosion but also the decline in fertility (chemical, physical and biological breakdown of the soil). (Young 1984). The adverse effect of soil erosion is not confined only to decrease in soil depth but ultimately to the loss loss of organic matter and plant nutrients and consequently to degradation of soil physical properties and crop yield decline ( Young 1984). It is important to note however that treating the benefits of soil conservation in isolation from other agricultural improvements does not assure adoption of the soil conservation practice (Young 1984). Integration of soil conservation is important ( Douglas 1988; Shaxson 1988). Sheng and Meiman (1988) stated reasons for the difficulty of farmers in adopting soil conservation practice. The reasons are as follows: i) long time for the result of soil conservation to be realized, ii) identification of benefits from soil conservation and iii) the need for big investments by farmers. It is important to note however that Williams and Walter (1988), in a terracing project in Venezuela, found that improvement in the living incomes and opportunites for employment, increases the difficulty of motivating the farmers to adopt soil conservation practices. Apparently when low income and underemployment prevail, farmers easily participate in soil conservation programmes (Williams and Walter 1988; Liao et al 1988). The adverse effect of soil erosion is not confined only to loss of soil particles but also the loss of organic matter and plant nutrients. As a result of this crop yield decline will occur (Young 1984). Conservation farming should serve as the basis for counteracting the problem of soil erosion. To carry out this approach in developing countries, novel approaches in extension and research are needed. The majority of the soil conservation techniques were developed in the United States of America under condtions different from the other parts of the world experiencing erosion (Sheng, 1982; Hudson 1988; Sheng 1988). The techniques that worked well in the United States were extrapolated to the tropics in the 1930s and 1940s. It took fifty years to realize that these methods were unsuitable for the tropics ( Hudson,1987; Hudson 1988). The dominant traditional farming system in the tropics are the shifting cultivation and related bush fallow systems (Okigbo and Greenland, 1976). The non-ac ceptance of the many recommendations on soil conservation methods is attributed to their in appropriateness and incompatibility with the farmers operating environment (Douglas, 1988). The following agricultural conditions in the United States of America paved the way for the development of soil conservation activities (Hudson,1982;Hudson 1987): Combined good topography and favourable climate Low population pressure for intensive land use Strong and sustained government support well educated and informed agriculture sector Readily available credit and financial support Reliable prices and market outlets for agricultural produce Highly developed and highly mechanized agricultural industry. According to Hudson (1987), the absence of these conditions in most developing countries made the North American approach to soil conseration in appropriate. The absence of political will, or the limitations in or lack of resources often hindered soil conservation programmes in developing countries. The main aim of soil conservation should be preventation rather than cure. Soil conservation activity should be focused mainly on preserving good land rather than reclaiming damaged land. Without waiting for visible soil erosion damage, farmers should be encouraged to understand that there is a need for soil conservation due to continuing reduction in agricultural yield (Hudson, 1987). Loss of agricultural productivity should be emphasized in any soil conservation programme. For sometime, soil erosion research activities had almost been exclusively directed towards uantfying soil loss, hence data on the effect of soil erosion on agriculture productivity is seriously lacking (Crosson and Stout, 1983; ASAE,1985; Follet and Stewart, 1985; Stocking, 1985). Removal of topsoil resulted in decline of yield of a variety of agricultural crops (El-Swaify, Dangler and Amstrong 1982). Factors like type of soil, depth of soil, fertility status, topography, and type of crop affected the size of the decline in agricultural yield (Frye et al, 1982; Langdale and Schrader, 1982; Schertz 1983). There is limited data for soil and crops in the tropics (Lal, 1977). The effects of soil erosion on soil productivity in the tropics are move severe than for temperate countries (Moberg, 1972). This is because of highly weathered soils, fragile fertility status and most crop nutrents are found in the topmost layer of the soil. There is also significant deterioration of physical qualities of the soil as a growing medium after soil erosion (Lo, 1990). Higher erosion rates, the more severe changes in chemical qualities resulting from erosion and the inability of the farmer to provide the necessary inputs for restoring those qualities to a sufficient level were the primary reasons given for these conclusions (El-Swaify, 1990). The benefits of soil conservation are not immediately realized in every case and may initially result in crop yield reductions (John 1988). Improvement in agricultural production, rather than mitigating soil erosion, is of more significance and desirable for the farmer, while prevention of soil loss is an unreal concept for them (Hudson, 1987). The new approach of soil conservation will be a mixture of both agronomy measures as well as mechanical works ( Tracy, 1988). Mechanical systems are frequently expensive, consume space and time, need regular maintenance and do not assure improved crop production (Roose, 1988). Too much emphasis put into mechanical works discourages effective soil conservation policies (Rose, 1989). Conservation farming systems include improved farming, with mechanical protection works being a component of last resort. This approach is consistent with the principle that improved agricultural production should lead to better soil erosion control (Hudson 1988). Biological measures provide immediately recognizable short term benefits to farmers. Any mechanical work involved in soil conservation must m aximize the use of locally available experts, minimize, the use of structures and required labour. Community involvement must be involved (Hudson, 1987). To gain acceptance by farmers, any proposed soil conservation strategy should offer short-term, apparent, rapid or immediately recognizable, directly effective benefits and positive results, particularly for subsistence farmers who work in a short-time scale and who comprise a large percentage of farmers in less developed countries (Harper and El-Swaify 1988; Hudson,1988; Lovejoy and Naiper, 1988; Sanders, 1988; Thomas 1988; Tracy, 1988; Wenner, 1988; Williams and Walter, 1988). Soil conservation techniques recommended for farmers should be simple, easily understood and demonstrated, low cost, productive, sustainable and acceptable (Douglas, 1988;Vonk 1988). Conservation measures should involve principles that can be applied to more than one situation. However, methods and techniques are often site specific and caution should be exercised in extrapolating them to other sites (Saunders 1988). Adoption of soil conservation technology is assured if the farmers have full understanding, support and participation in all the stages of the project, from planning, implementation to maintenance (Harper and El-Swaify, 1988; Sanders, 1988; Vonk 1988; Tracy 1988). Farmers full participation is ensured if they are convinced that their relevant and important needs can be adequately met (Sanders 1988). Thus the farmer needs to be recognized as part of the solution rather than a part of the problem (Hudson,1987; Hudson,1988).

Imaginative Freedom of Birches :: Robert Frost Birches Essays

Imaginative Freedom of Birches        Ã‚  Ã‚   In "Birches" (Mountain Interval, 1916) Frost begins to probe the power of his redemptive imagination as it moves from its playful phase toward the brink of dangerous transcendence. The movement into transcendence is a movement into a realm of radical imaginative freedom where (because redemption has succeeded too well) all possibilities of engagement with the common realities of experience are dissolved. In its moderation, a redemptive consciousness motivates union between selves as we have seen in "The Generations of Men," or in any number of Frost's love poems. But in its extreme forms, redemptive consciousness can become self-defeating as it presses the imaginative man into deepest isolation. "Birches" begins by evoking its core image against the background of a darkly wooded landscape: When I see birches bend to left and right Across the lines of straighter darker trees, I like to think some boy's been swinging them. But swinging doesn't bend them down to stay As ice storms do. The pliable, malleable quality of the birch tree captures the poet's attention and kicks off his meditation. Perhaps young boys don't bend birches down to stay, but swing them they do and thus bend them momentarily. Those "straighter, darker trees," like the trees of "Into My Own" that "scarcely show the breeze," stand ominously free from human manipulation, menacing in their irresponsiveness to acts of the will. The malleability of the birches is not total, however, and the poet is forced to admit this fact into the presence of his desire, like it or not. The ultimate shape of mature birch trees is the work of objective natural force, not human activity. Yet after conceding the boundaries of imagination's subjective world, the poet seems not to have constricted himself but to have been released.   Ã‚  Ã‚   Often you must have seen them Loaded with ice a sunny winter morning After a rain. They click upon themselves As the breeze rises, and turn many-colored As the stir cracks and crazes their enamel. Soon the sun's warmth makes them shed crystal shells Shattering and avalanching on the snow crust-- Such heaps of broken glass to sweep away You'd think the inner dome of heaven had fallen. Fascinated as he is by the show of loveliness before him, and admiring as be is of nature as it performs the potter's art, cracking and crazing the enamel of ice coating on the birch trees, it is not finally the thing itself (the ice-coated trees) that interests the poet but the strange association be is tempted to make: "You'd think the inner dome of heaven had fallen.

Having A Gun :: essays research papers

Having A Gun Very often in life I would find myself strongly disagreeing and upholding the totally opposite point of view about the actions and behavior of those, whose deeds seemed to me rather disadvantageous and harmful to the entire community or society. These kind of actions were mostly coming from government authorities, and quite obviously, there was not much that could have been done in order to refute or override them. Therefore, not only once, the idea of having adequate power and authority to ban these kind of pernicious practices, would appeal to me. For the purpose of decreasing the crime rate, that was the top concern of the Ukrainian citizen, in 1994, some misguided politicians in government adopted the legislation repealing the previous amendment and thus, abolishing the constitutional right to own the handguns. Banning the sale of firearms seems to me a most malicious and reckless deed, that instead of safeguarding and protecting, endangers more the entire society. The Government justified this act by saying that it would protect the innocent citizens. But it failed to even entertain the notion that the enactment of this law would come to protect the right of those who violate the rights of others. It has never occurred to authorities that vicious criminals, in spite of this legislation, will still manage somehow to get the firearms. Innocent people, however, will suffer, because they will be less likely to obtain handguns in order to protect themselves and their families. Therefore, it would not be hard to imagine the carnage of the citizens, should there not be any guns in their homes. The criminals would walk in at any time they desired, they would take whatever they wanted, rape whom they wanted, and shoot whoever would resist. The Government defended the enactment of this law by declaring that people could not be secure as long as there would be handguns around; they could not be secure when three million people in the country had shotguns stuck in the glove compartment of their cars, bedside drawers, pockets and kitchen cabinets. But could they be secure if some criminal would try to take away somebody's car under the threat, rob and rape somebody in the street or try to burglarize somebody's home, knowing that they would not have any guns to protect themselves? The prompt and correct answer is "NO". The government was established to insure that none of our rights would be violated or taken away. It seems to me that the government, by infringing the right of people to keep and bear arms, has failed to provide its citizens with

Eulogy for Friend :: Eulogies Eulogy

Eulogy for Friend The phone rang in the early hours of the morning. Rolf G. informed us that Michael had suffered a heart attack a few hours earlier and had not survived. My wife whispered a few words I could not hear, sat silently on the edge of the bed for a moment, then turned to me and said, "Michael passed away at the airport, its just not fair. He was doing so well." No, it was just not fair. We try to share with Michael's family, with Kathy, Molly and Tom, Molly, Clint and Wendy and their families the grief they feel, but it is not really in our power to do so. We are compelled to measure the loss of our friend and colleague, father and husband each in our own way and turn instead to what we can share, the extraordinary life that touched us all. I spoke with Michael several times well before we had actually met. When it was determined that Marilyn and I were coming to a university in far off Montana, he called us in Washington, D.C. to welcome us, to ask questions about courses I wanted to teach, shared information about students and the university. A few weeks after the Fall term began that year, he came into my office and asked me a question about a Native American tribe that lived in the Montana western border region. "How did they subsist," I think he asked. I replied that they hunted and fished and planted crops, they were a "seasonal people." He liked that phrase. "Ya, Ya" and then he was back to his typewriter. Some months later, the first addition of his book Montana: A History of Two Centuries, written with colleague Dick R., came out. He gave me a copy and I was perusing through the early chapters, when there in the middle of a discussion about Montana's native people, was "Historian Thomas R. Wessel refers to them as ‘seasonal people'." It was a small matter that hardly enhanced his scholarly reputation of mine for that matter, but I came to learn it was typical. A quiet, generous gesture followed in the years we spent together in the Department of History and Philosophy, and after, when he climbed the administrative ladder to the President's Office. I would soon learn that I was hardly alone as a recipient of Michael's generosity and concern. Eulogy for Friend :: Eulogies Eulogy Eulogy for Friend The phone rang in the early hours of the morning. Rolf G. informed us that Michael had suffered a heart attack a few hours earlier and had not survived. My wife whispered a few words I could not hear, sat silently on the edge of the bed for a moment, then turned to me and said, "Michael passed away at the airport, its just not fair. He was doing so well." No, it was just not fair. We try to share with Michael's family, with Kathy, Molly and Tom, Molly, Clint and Wendy and their families the grief they feel, but it is not really in our power to do so. We are compelled to measure the loss of our friend and colleague, father and husband each in our own way and turn instead to what we can share, the extraordinary life that touched us all. I spoke with Michael several times well before we had actually met. When it was determined that Marilyn and I were coming to a university in far off Montana, he called us in Washington, D.C. to welcome us, to ask questions about courses I wanted to teach, shared information about students and the university. A few weeks after the Fall term began that year, he came into my office and asked me a question about a Native American tribe that lived in the Montana western border region. "How did they subsist," I think he asked. I replied that they hunted and fished and planted crops, they were a "seasonal people." He liked that phrase. "Ya, Ya" and then he was back to his typewriter. Some months later, the first addition of his book Montana: A History of Two Centuries, written with colleague Dick R., came out. He gave me a copy and I was perusing through the early chapters, when there in the middle of a discussion about Montana's native people, was "Historian Thomas R. Wessel refers to them as ‘seasonal people'." It was a small matter that hardly enhanced his scholarly reputation of mine for that matter, but I came to learn it was typical. A quiet, generous gesture followed in the years we spent together in the Department of History and Philosophy, and after, when he climbed the administrative ladder to the President's Office. I would soon learn that I was hardly alone as a recipient of Michael's generosity and concern.

Practical Book Review

GUIDELINES FOR THE Practical Book Review By [Your Name] Student ID: [type ID w/out brackets] Presented to [Dr. Professor’s Name] In partial fulfillment of the requirements of Introduction to Pastoral Counseling PACO 500 Liberty Baptist Theological Seminary Lynchburg, VA PRACTICAL BOOK REVIEW [ONE]: [AUTHOR’S LAST NAME] My Summation Communication is a tremendously important part of the human experience. Any effort to improve one’s skills is valuable. Most people think they listen well when having a conversation, but the reality is that most people walk away from a conversation feeling unheard, misunderstood, and disconnected.Petersen uses real world experiences to teach the reader how to handle difficult situations and people. In Petersen’s concept, improvement in listening skills will result in an overall improvement in relationships. Peterson describes the flat brain syndrome in his book. Stomach functions consist of people’s emotions or feelings – those inner nudges that let people know when they’re uncomfortable, happy, excited, interested, attracted, irritable, angry, resentful, frustrated, and curious. Feelings are people’s internal responses to the world around them, to what they’re thinking, and to their bodies.Heart functions give and receive concerns, suggestions, and support. They are ready to consider many options and possibilities. Healthy hearts recognize that people don’t possess â€Å"the whole truth,† but are confident both in owning their views and remaining open to the views of others. The head functions incorporate thinking, planning, remembering, reviewing, deciding, and rationalizing. Petersen points out that a correct understanding of these relationships can make the difference when it comes to lessening conflicts.A unbalanced blend of either too much brain or too much stomach creates flat-brained syndrome where it is all emotion and no thought, or the flat-brain tango, all thought with no emotion. The Talker-Listener Process is the key to creating an environment where two or more people can talk and listen to each other. This promotes a healthy communication atmosphere. The Talker Listener Card, (TLC), can help those who want to improve their ability to interact with others and communicate better. This is especially true for the listening aspect of the relationship.Peterson explains that if we would all go back to our kid-learned skill of taking turns, communication , or speaking vs. listening, would be better achieved. We should focus on listening to one person’s point of view at one time to establish feeling heard, feeling safe, and feeling understood. This will also directly lead to feeling more of a human connection and thus broadening our relationships with others. The TLC helps this process because it allows for each person (the talker and listener) to roll play while having the conversation. Each has a part to play and respon sibilities to take on.The TLC simply states these roles to help remind one what to do. Peterson moves on to explain the way people communicate, especially when asking questions. He refers to this process as similar to being in a courtroom. The way people ask questions makes a huge difference in the outcomes of the questions. People tend to ask questions in a way that sort of guides ones thinking when answering instead of just getting to the point and saying what one really feels. If people would just come out and say what they are feeling, relationships would be better off according to Peterson.Peterson continues to outline several listening techniques. The art of listening has to be practiced in order to succeed. One must first provide a safe place or environment for the talker in order to promote peace and safety. After this is established, the goal is to really listen and understand what the talker is trying to say. Also, clarifying the problem for the talker is very important in order to fully comprehend the situation and how to effectively listen and respond to the talker. In the final process, Petersen puts it all together to examples how to use the process of talking and listening effectively.He gives examples of how to use his theory of â€Å"Flat Brained Syndrome† to overcome issues and people with the syndrome. In the end, he shows you how to become a person that good things happen to due to having great communication skills. My Reflection My Investigation My Application The most crucial element after reading this book is the practical application that one would start to incorporate into their life. I have learned now that I am more committed to becoming an actual listener instead of being a talker. Too often am I getting caught up in the notion that my ideas are somehow more important than those that I am listening to.Peterson said, â€Å"Listen first (and longer) and then, talk second† (125). Peterson has given me methods of becoming a better listener, which in turn will enrich my relationships with people. I will use the skills that are outlined in chapter eighteen to improve the way I listen. I will do this process slowly in order to ensure a more successful outcome by starting with one or two skills first and then moving onto another skill once the preceeding skill was mastered. As a future minister, the ability to really listen is going to be a crucial aspect.One important skill that I need to incorporate first is my ability to repeat accurately what the speaker is trying to say. I have a tendency to take what others say and rephrase it while putting my own twist on it. Peterson says that this is common. In giving feedback, listeners routinely alter the content of what other people say (Peterson 2007). I did not realize how important this is to the listener until Peterson pointed it out. The point is that most people do not seek advice to solve a problem. Most people have the ability to solve problems on the ir own but need a sounding board to bounce thoughts off of when finding a solution.In order to successfully help people as a minister, I must work on my communication skills from here on out. I will improve on being more direct with my words and thoughts so that the talking time that I do have will be more goal oriented and satisfying. I will also learn how to become a better listener. Listening to people and their feelings or thoughts is one of my main concerns when it comes to giving people the proper soul care they deserve from a minister. Peterson’s book has only helped me discover ways to put this into practice. References

Nitric oxide therapy

There is not much use for the lungs during the fetal life. At such stage, the function of the lungs is carried out by the placenta through the umbilical cord. Fetal life is characterized by a high pulmonary vascular resistance (PVR) with pulmonary blood flow being restricted to a less than 10% lung-directed cardiac output. Blood vessels that connect the heart and the lungs are constricted, sending the circulating blood back to the heart through the ductus arteriosus, a blood vessel that functions only in fetuses. In other words, the lungs in the fetal stage are bypassed.At birth, when the lungs finally assume the function of gas exchange, the PVR decreases, allowing for an increase in pulmonary blood flow. The blood vessel that is previously constricted, favoring blood flow to the ductus arteriosus is now relaxed, simultaneously with the permanent closure of the ductus arteriosus. This happens as the lungs become ventilated and the alveolar oxygen tension is increased.Persistent Pulm onary Hypertansion occurs when at birth, the lung circulation fails to achieve the normal drop in PVR, preventing the transition from fetal to newborn circulation. This failure results in the continuous functioning of the ductus arteriosus which impairs the flow of blood from the heart to the lungs and limits the amount of oxygen that can be picked up by the blood to be delivered to the different parts of the body. The blood that flows back to the heart remains in an unoxygenated state which could lead to the development of refractory hypoxemia, respiratory distress and acidosis.It is only in 1987 when nitric oxide (NO) was recognized as a key endothelial-derived vasodilator molecule. From then, research has been expanded to establish the role of NO throughout the body, and to discover its therapeutic potential.   To appreciate the effects of NO in alleviating pulmonary hypertension, it is important to gain understanding of its chemistry and mechanism of action.Nitric Oxide is a g aseous compound that rapidly diffuses across membranes and has a single unpaired electron. This explains its high reactivity, especially to Hemoglobin (Hb) in the blood. This nature of the compound accounts for its noted biological significance. It has been discovered to function as stimulant in the release of hormones; as neurotransmitter; a significant participant in the magnification of synaptic actions and learning processes; and an inhibitor in platelet aggregation, which makes it a marvel in the field of cardiology.In the field of pulmonology, nitric oxide is valued for its vasodilatory effect in the blood vessels. This effect can be explained by the mechanism involving the compound's diffusion from the vascular endothelial cells to the subjacent smooth muscles of the pulmonary vessels. From here, NO activates the enzyme guanylate cyclase to change conformation to promote smooth muscle relaxation by converting GTP to cGMP.   This vasodilatory effect signals the mechanism to modulate blood flow and vascular tone.Given the mechanism of action, it is easy to surmise how NO can be utilized as a therapeutic agent in the management of blood-vessel-related diseases such as those related to the heart (hypertension), the reproductive system(erectile dysfunction) and in this case, the lungs (Persistent Pulmonary Hypertension in infants (PPHN)).Before NO, treatments used in infant PPHN are hyperventilation, continuous infusion of alkali, tube vasodilation and vasodilator drugs. A study on the effects of these various treatments was done by Ellington, Jr., et. al., (2001) showing no specific therapy clearly associated with the reduction in mortality in infants. In determining whether therapies were equivalent, the study showed that hyperventilation reduced the risk of extracorporeal membrane oxygenation (ECMO) with no oxygen increase at 28 days, while alkali infusion increased the use of ECMO as well as an increase in the use of oxygen at 28 days (Ellington, Jr., et. al., 2001). ECMO is a highly invasive procedure that requires major surgery, performed in serious cases of PPHN when patients fail to respond to treatments.It is only after post-lab studies were able to identify the role of NO-cGMP signaling in the regulation of lung circulation that NO therapy was developed for PPHN (Channick, R., et. al., 1994). Like previous treatment methods, NO therapy improves oxygenation as well as reduces the risk of ECMO in infants with PPHN (Oliveira, et. al., 2000). But because nitric oxide is capable of acting on its own upon inhalation to relax the blood vessels and improve circulation, it is considered as a less invasive procedure in the management of infants with PPHN compared to the previous treatments mentioned in the preceding paragraphs.The efficiency of the treatment procedure can be determined by observing its effect on the patient's ventilation and blood flow, which is a determinant of the efficiency of transpulmonary oxygenation and partia l pressure of oxygen in the systemic arterial blood (Ichinose, et. al., 2004). NO therapy enhances the mechanism by which blood flow is redistributed toward regions in the lungs with better ventilation and higher intra-alveolar partial pressure of oxygen (Ichinose, et. al., 2004).Other treatments used in the management of PPHN such as tube ventilation, alkalosis and intravenous vasodilators were shown to be effective in ameliorating pulmonary hypertension in some infants, but in many instances, it does not, as ECMO almost always becomes a necessity in saving the life of the infants (Ichinose, et. al., 2004). A type of hyperventilation has been proven not to increase the risk of ECMO, but unlike NO-therapy (Ellington, Jr., et. al., 2001), it is invasive as to require a tube inserted inside the infant's trachea.In patients with moderate PPHN, there is an improvement in arterial p a O 2, reduced necessity of ventilator support and low risk of progression to severe PPHN (Sadiq, et. al., 2003) and this, without the risk of increasing the incidence of adverse outcomes when the age of 1 year is reached (Clark, et. al. 2003). Inhaled NO is able to rapidly increase the arterial oxygen tension and increase the blood flow in the lungs without causing systemic hypotension (Roberts, 1992; Kinsella, 1992). No apparent increase in morbidity has been shown after one year of treatment with NO (Aparna and Hoskote, 2008). For high-risk infants with PPHN, inhaled NO has been found to lessen the risk of pulmonary hypertensive crisis (PHTC) after congenital heart surgery (Miller, et. al. 2000).Studies on the role of NO in the management of PPHM show that while it is therapeutic, it also prevents the occurrence of chronic lung disease which affects morbidity. Vascular cell proliferation and pulmonary vascular disease have been shown to decrease with NO in the newborn (Roberts, et. al., 1995). In addition, while NO treatment can be more costly, it is the most cost-effective among oth er methods because of the reduced need for ECMO (Angus, et. al. 2003). For these reasons, it is understandable why NO therapy seems to have taken over in the area of PPHN treatment.ReferencesAngus DC, Clermont G, Watson RS, et al. (2003). Cost-effectiveness of inhaled nitric oxide in the treatment of neonatal respiratory failure in the United States. Pediatrics. 112, 1351–1360.Aparna U., Hoskote, MD., et. al. (2008). Airway function in infants treated with inhaled nitric oxide for persistent pulmonary hypertension. Pediatr Pulmonol. 43, 224-235.Channick R, Hoch R, Newhart J, et al. (1994). Improvement in pulmonary hypertension and hypoxemia during nitric oxide inhalation in a patient with end-stage pulmonary fibrosis. Am J Respir Crit Care Med. 149, 811-814Clark, RH., Huckaby, JL., et. al. (2003). Low-Dose Nitric Oxide Therapy for Persistent Pulmonary Hypertension: 1-Year Follow-up. Journal of Perinatology. 23, 300.Ellington Jr, Marty, O'Reilly, et. al. (2001). Child Health S tatus, Neurodevelopmental Outcome, and Parental Satisfaction in a Randomized, Controlled Trial of Nitric Oxide for Persistent Pulmonary Hypertension of the Newborn. Pediatrics,107.Ichinose F, Roberts JD, et.al. (2004). A Selective Pulmonary Vasodilator: Current Uses and Therapeutic Potential. Circulation. 109, 3106-3111. Kinsella JP, Neish SR, Shaffer E, et al. (1992). Low-dose inhalation nitric oxide in persistent pulmonary hypertension of the newborn. Lancet.   340, 819–820.Miller O, Tang SW, et. al. (2000) Inhaled nitric oxide and prevention of pulmonary hypertension after congenital heart surgery: A randomised double-blind study. The Lancet. 356: 9240, 1464.Oliveira cac, et. al. (2000). Inhaled Nitric oxide in the management of persistent pulmonary hypertension of the newborn: a meta-analysis. Rev. Hosp. Clin. Fac. Med. S., 55 (4): 145-154, 2000Roberts JD Jr, Polaner DM, Lang P, et al. (1992). Inhaled nitric oxide in persistent pulmonary hypertension of the newborn. Lan cet. 340, 818–819.Roberts JD Jr, Roberts CT, Jones RC, et al. (1995). Continuous nitric oxide inhalation reduces pulmonary arterial structural changes, right ventricular hypertrophy, and growth retardation in the hypoxic newborn rat. Circ Res. 76, 215-222.Sadiq HF, Mantych G, et. al. (2003). Inhaled Nitric Oxide in the Treatment of Moderate Persistent Pulmonary Hypertension of the Newborn: A Randomized Controlled, Multicenter Trial. Journal of Perinatology.   23, (2).98

Health Care Email Essay

Thinking back a hundred years ago the history of health care has evolved and has become one of the most demanding fields to work in. The ultimate goal of health care is to treat, prevent or to intervene for those who are ill. Technology is also a major evolution that is now a vital role in the health care system. It allows patients to become more involved with their healthcare. They can follow up on test results, make appointments, and contact their doctors with the progression of technology. Not only has technology evolved but medication is another area that has improved the lives of many, back a hundred years ago the various medication was not available. The future has so much in store for those in the health care field. There are many interesting areas of the health care field. The one thing that interests me most is how disease treatment has changed the path to healing. The idea of medicine has change the look on life of healing and living. Medicine has change the ways we care for our customer know as our patient. In the earlier centuries, epidemics like cholera and smallpox were a widespread across countries; now those diseases are rarely heard of. With the research and implementation of new medicines most of the diseases that were killing thousands of people are now nonexistent. Nurses are the care takers in the health care field. With nurses patients receive one on one care, in many areas of the health care field. Nursing comes from the heart and spirit and truly from within. Healthcare was my number one choice field to work in. After working in a nursing home for many years showed me the reward for caring for others. I have learned many lessons in the healthcare field both positive and negative. . There are many resources and information on the history of health care in the U.S Department of Health & Human Services, Centers for Disease Control and Prevention, and Public Health Services. These are only a few of the resources were information on the  history of health can be found. There are many aspect and field to go into, but you have to know which area of expertise or group and how they all tie into the health care.

Recovery System Dbms

17. Recovery System in DBMS – Presentation Transcript 1. Chapter 17: Recovery System * Failure Classification * Storage Structure * Recovery and Atomicity * Log-Based Recovery * Shadow Paging * Recovery With Concurrent Transactions * Buffer Management * Failure with Loss of Nonvolatile Storage * Advanced Recovery Techniques * ARIES Recovery Algorithm * Remote Backup Systems 2. Failure Classification * Transaction failure : * Logical errors : transaction cannot complete due to some internal error condition * System errors : the database system must terminate an active transaction due to an error condition (e. . , deadlock) * System crash : a power failure or other hardware or software failure causes the system to crash. * Fail-stop assumption : non-volatile storage contents are assumed to not be corrupted by system crash * Database systems have numerous integrity checks to prevent corruption of disk data * Disk failure : a head crash or similar disk failure destroys all or part of disk storage * Destruction is assumed to be detectable: disk drives use checksums to detect failures 3. Recovery Algorithms Recovery algorithms are techniques to ensure database consistency and transaction atomicity and durability despite failures * Focus of this chapter * Recovery algorithms have two parts * Actions taken during normal transaction processing to ensure enough information exists to recover from failures * Actions taken after a failure to recover the database contents to a state that ensures atomicity, consistency and durability 4. Storage Structure * Volatile storage : * does not survive system crashes * examples: main memory, cache memory * Nonvolatile storage : survives system crashes * examples: disk, tape, flash memory, non-volatile (battery backed up) RAM * Stable storage : * a mythical form of storage that survives all failures * approximated by maintaining multiple copies on distinct nonvolatile media 5. Stable-Storage Implementation * Maintain multiple co pies of each block on separate disks * copies can be at remote sites to protect against disasters such as fire or flooding. * Failure during data transfer can still result in inconsistent copies: Block transfer can result in * Successful completion Partial failure: destination block has incorrect information * Total failure: destination block was never updated * Protecting storage media from failure during data transfer (one solution): * Execute output operation as follows (assuming two copies of each block): * Write the information onto the first physical block. * When the first write successfully completes, write the same information onto the second physical block. * The output is completed only after the second write successfully completes. 6.Stable-Storage Implementation (Cont. ) * Protecting storage media from failure during data transfer (cont. ): * Copies of a block may differ due to failure during output operation. To recover from failure: * First find inconsistent blocks: * Expensive solution : Compare the two copies of every disk block. * Better solution : * Record in-progress disk writes on non-volatile storage (Non-volatile RAM or special area of disk). * Use this information during recovery to find blocks that may be inconsistent, and only compare copies of these. Used in hardware RAID systems * If either copy of an inconsistent block is detected to have an error (bad checksum), overwrite it by the other copy. If both have no error, but are different, overwrite the second block by the first block. 7. Data Access * Physical blocks are those blocks residing on the disk. * Buffer blocks are the blocks residing temporarily in main memory. * Block movements between disk and main memory are initiated through the following two operations: * input ( B ) transfers the physical block B to main memory. output ( B ) transfers the buffer block B to the disk, and replaces the appropriate physical block there. * Each transaction T i has its private work-area in which local copies of all data items accessed and updated by it are kept. * T i ‘s local copy of a data item X is called x i . * We assume, for simplicity, that each data item fits in, and is stored inside, a single block. 8. Data Access (Cont. ) * Transaction transfers data items between system buffer blocks and its private work-area using the following operations : * read ( X ) assigns the value of data item X to the local variable x i . write ( X ) assigns the value of local variable x i to data item { X } in the buffer block. * both these commands may necessitate the issue of an input (B X ) instruction before the assignment, if the block B X in which X resides is not already in memory. * Transactions * Perform read ( X ) while accessing X for the first time; * All subsequent accesses are to the local copy. * After last access, transaction executes write ( X ). * output ( B X ) need not immediately follow write ( X ).System can perform the output operation when it deems fi t. 9. Example of Data Access x Y A B x 1 y 1 buffer Buffer Block A Buffer Block B input(A) output(B) read(X) write(Y) disk work area of T 1 work area of T 2 memory x 2 10. Recovery and Atomicity * Modifying the database without ensuring that the transaction will commit may leave the database in an inconsistent state. * Consider transaction T i that transfers $50 from account A to account B ; goal is either to perform all database modifications made by T i or none at all. Several output operations may be required for T i (to output A and B ). A failure may occur after one of these modifications have been made but before all of them are made. 11. Recovery and Atomicity (Cont. ) * To ensure atomicity despite failures, we first output information describing the modifications to stable storage without modifying the database itself. * We study two approaches: * log-based recovery , and * shadow-paging * We assume (initially) that transactions run serially, that is, one after the other. 12 . Log-Based Recovery A log is kept on stable storage. * The log is a sequence of log records , and maintains a record of update activities on the database. * When transaction T i starts, it registers itself by writing a ;T i start ;log record * Before T i executes write ( X ), a log record ;T i , X, V 1 , V 2 ; is written, where V 1 is the value of X before the write, and V 2 is the value to be written to X . * Log record notes that T i has performed a write on data item X j X j had value V 1 before the write, and will have value V 2 after the write. When T i finishes it last statement, the log record ; T i commi t; is written. * We assume for now that log records are written directly to stable storage (that is, they are not buffered) * Two approaches using logs * Deferred database modification * Immediate database modification 13. Deferred Database Modification * The deferred database modification scheme records all modifications to the log, but defers all the write s to after part ial commit. * Assume that transactions execute serially Transaction starts by writing ;T i start ; record to log. * A write ( X ) operation results in a log record ;T i , X, V; being written, where V is the new value for X * Note: old value is not needed for this scheme * The write is not performed on X at this time, but is deferred. * When T i partially commits, ; T i commit ; is written to the log * Finally, the log records are read and used to actually execute the previously deferred writes. 14. Deferred Database Modification (Cont. ) During recovery after a crash, a transaction needs to be redone if and only if both ;T i start ; and; T i commit ; are there in the log. * Redoing a transaction T i ( redo T i ) sets the value of all data items updated by the transaction to the new values. * Crashes can occur while * the transaction is executing the original updates, or * while recovery action is being taken * example transactions T 0 and T 1 ( T 0 executes before T 1 ): * T 0 : rea d ( A ) T 1 : read ( C ) * A: – A – 50 C:- C- 100 Write ( A ) write ( C ) * read ( B ) * B:- B + 50 * write ( B ) 15. Deferred Database Modification (Cont. ) * Below we show the log as it appears at three instances of time. * If log on stable storage at time of crash is as in case: * (a) No redo actions need to be taken * (b) redo( T 0 ) must be performed since ; T 0 commi t; is present * (c) redo ( T 0 ) must be performed followed by redo( T 1 ) since * ; T 0 commit ; and ; T i commit; are present 16. Immediate Database Modification The immediate database modification scheme allows database updates of an uncommitted transaction to be made as the writes are issued * since undoing may be needed, update logs must have both old value and new value * Update log record must be written before database item is written * We assume that the log record is output directly to stable storage * Can be extended to postpone log record output, so long as prior to execution of an output ( B ) operation for a data block B, all log records corresponding to items B must be flushed to stable storage * Output of updated blocks can take place at any time before or after transaction commit * Order in which blocks are output can be different from the order in which they are written. 17. Immediate Database Modification Example * Log Write Output * ; T 0 start ; ; T 0 , A, 1000, 950; * T o , B, 2000, 2050 * A = 950 * B = 2050 * ; T 0 commit ; * ; T 1 start ; * ; T 1 , C, 700, 600; * C = 600 * B B , B C * ; T 1 commit ; * B A * Note: B X denotes block containing X . x 1 18. Immediate Database Modification (Cont. ) * Recovery procedure has two operations instead of one: * undo ( T i ) restores the value of all data items updated by T i to their old values, going backwards from the last log record for T i * redo ( T i ) sets the value of all data items updated by T i to the new values, going forward from the first log record for T i * Both operations must be idempotent That is , even if the operation is executed multiple times the effect is the same as if it is executed once * Needed since operations may get re-executed during recovery * When recovering after failure: * Transaction T i needs to be undone if the log contains the record ;T i start ; , but does not contain the record ;T i commit ; . * Transaction T i needs to be redone if the log contains both the record ;T i start ; and the record ;T i commit ; . * Undo operations are performed first, then redo operations. 19. Immediate DB Modification Recovery Example * Below we show the log as it appears at three instances of time. * Recovery actions in each case above are: * (a) undo ( T 0 ): B is restored to 2000 and A to 1000. (b) undo ( T 1 ) and redo ( T 0 ): C is restored to 700, and then A and B are * set to 950 and 2050 respectively. * (c) redo ( T 0 ) and redo ( T 1 ): A and B are set to 950 and 2050 * respectively. Then C is set to 600 20. Checkpoints * Problems in recovery procedure as discusse d earlier : * searching the entire log is time-consuming * we might unnecessarily redo transactions which have already * output their updates to the database. * Streamline recovery procedure by periodically performing checkpointing * Output all log records currently residing in main memory onto stable storage. * Output all modified buffer blocks to the disk. * Write a log record ; checkpoint ; onto stable storage. 1. Checkpoints (Cont. ) * During recovery we need to consider only the most recent transaction T i that started before the checkpoint, and transactions that started after T i . * Scan backwards from end of log to find the most recent ; checkpoint ; record * Continue scanning backwards till a record ;T i start ; is found. * Need only consider the part of log following above star t record. Earlier part of log can be ignored during recovery, and can be erased whenever desired. * For all transactions (starting from T i or later) with no ;T i commit ; , execute undo ( T i ). (D one only in case of immediate modification. * Scanning forward in the log, for all transactions starting from T i or later with a ;T i commit ; , execute redo ( T i ). 22. Example of Checkpoints * T 1 can be ignored (updates already output to disk due to checkpoint) * T 2 and T 3 redone. * T 4 undone T c T f T 1 T 2 T 3 T 4 checkpoint system failure 23. Shadow Paging * Shadow paging is an alternative to log-based recovery; this scheme is useful if transactions execute serially * Idea: maintain two page tables during the lifetime of a transaction –the current page table , and the shadow page table * Store the shadow page table in nonvolatile storage, such that state of the database prior to transaction execution may be recovered. Shadow page table is never modified during execution * To start with, both the page tables are identical. Only current page table is used for data item accesses during execution of the transaction. * Whenever any page is about to be written for the fi rst time * A copy of this page is made onto an unused page. * The current page table is then made to point to the copy * The update is performed on the copy 24. Sample Page Table 25. Example of Shadow Paging Shadow and current page tables after write to page 4 26. Shadow Paging (Cont. ) * To commit a transaction : * 1. Flush all modified pages in main memory to disk * 2. Output current page table to disk * 3.Make the current page table the new shadow page table, as follows: * keep a pointer to the shadow page table at a fixed (known) location on disk. * to make the current page table the new shadow page table, simply update the pointer to point to current page table on disk * Once pointer to shadow page table has been written, transaction is committed. * No recovery is needed after a crash — new transactions can start right away, using the shadow page table. * Pages not pointed to from current/shadow page table should be freed (garbage collected). 27. Show Paging (Cont. ) * A dvantages of shadow-paging over log-based schemes * no overhead of writing log records * recovery is trivial * Disadvantages : * Copying the entire page table is very expensive Can be reduced by using a page table structured like a B + -tree * No need to copy entire tree, only need to copy paths in the tree that lead to updated leaf nodes * Commit overhead is high even with above extension * Need to flush every updated page, and page table * Data gets fragmented (related pages get separated on disk) * After every transaction completion, the database pages containing old versions of modified data need to be garbage collected * Hard to extend algorithm to allow transactions to run concurrently * Easier to extend log based schemes 28. Recovery With Concurrent Transactions * We modify the log-based recovery schemes to allow multiple transactions to execute concurrently. * All transactions share a single disk buffer and a single log * A buffer block can have data items updated by one or more transactions * We assume concurrency control using strict two-phase locking; * i. e. the updates of uncommitted transactions should not be visible to other transactions * Otherwise how to perform undo if T1 updates A, then T2 updates A and commits, and finally T1 has to abort? * Logging is done as described earlier. Log records of different transactions may be interspersed in the log. * The checkpointing technique and actions taken on recovery have to be changed * since several transactions may be active when a checkpoint is performed. 29. Recovery With Concurrent Transactions (Cont. ) * Checkpoints are performed as before, except that the checkpoint log record is now of the form ; checkpoint L ; where L is the list of transactions active at the time of the checkpoint * We assume no updates are in progress while the checkpoint is carried out (will relax this later) * When the system recovers from a crash, it first does the following: * Initialize undo-list and redo-list to empt y Scan the log backwards from the end, stopping when the first ; checkpoint L ; record is found. For each record found during the backward scan: * if the record is ; T i commit ;, add T i to redo-list * if the record is ; T i start ;, then if T i is not in redo-list , add T i to undo-list * For every T i in L , if T i is not in redo-list , add T i to undo-list 30. Recovery With Concurrent Transactions (Cont. ) * At this point undo-list consists of incomplete transactions which must be undone, and redo-list consists of finished transactions that must be redone. * Recovery now continues as follows: Scan log backwards from most recent record, stopping when ; T i start ; records have been encountered for every T i in undo-list . * During the scan, perform undo for each log record that belongs to a transaction in undo-list . * Locate the most recent ; checkpoint L ; record. * Scan log forwards from the ; checkpoint L ; record till the end of the log. * During the scan, perform redo for e ach log record that belongs to a transaction on redo-list 31. Example of Recovery * Go over the steps of the recovery algorithm on the following log: * ; T 0 star t; * ; T 0 , A , 0, 10; * ; T 0 commit ; * ; T 1 start ; * ; T 1 , B , 0, 10; ; T 2 start ; /* Scan in Step 4 stops here */ * ; T 2 , C , 0, 10; * ; T 2 , C , 10, 20; * ;checkpoint { T 1 , T 2 }; * ; T 3 start ; * ; T 3 , A , 10, 20; * ; T 3 , D , 0, 10; * ; T 3 commit ; 32. Log Record Buffering * Log record buffering : log records are buffered in main memory, instead of of being output directly to stable storage. * Log records are output to stable storage when a block of log records in the buffer is full, or a log force operation is executed. * Log force is performed to commit a transaction by forcing all its log records (including the commit record) to stable storage. Several log records can thus be output using a single output operation, reducing the I/O cost. 33. Log Record Buffering (Cont. ) * The rules below must be followed if log records are buffered: * Log records are output to stable storage in the order in which they are created. * Transaction T i enters the commit state only when the log record ; T i commit ; has been output to stable storage. * Before a block of data in main memory is output to the database, all log records pertaining to data in that block must have been output to stable storage. * This rule is called the write-ahead logging or WAL rule * Strictly speaking WAL only requires undo information to be output 34. Database Buffering Database maintains an in-memory buffer of data blocks * When a new block is needed, if buffer is full an existing block needs to be removed from buffer * If the block chosen for removal has been updated, it must be output to disk * As a result of the write-ahead logging rule, if a block with uncommitted updates is output to disk, log records with undo information for the updates are output to the log on stable storage first. * No updates should be i n progress on a block when it is output to disk. Can be ensured as follows. * Before writing a data item, transaction acquires exclusive lock on block containing the data item * Lock can be released once the write is completed. * Such locks held for short duration are called latches . Before a block is output to disk, the system acquires an exclusive latch on the block * Ensures no update can be in progress on the block 35. Buffer Management (Cont. ) * Database buffer can be implemented either * in an area of real main-memory reserved for the database, or * in virtual memory * Implementing buffer in reserved main-memory has drawbacks: * Memory is partitioned before-hand between database buffer and applications, limiting flexibility. * Needs may change, and although operating system knows best how memory should be divided up at any time, it cannot change the partitioning of memory. 36. Buffer Management (Cont. ) Database buffers are generally implemented in virtual memory in spite of some drawbacks: * When operating system needs to evict a page that has been modified, to make space for another page, the page is written to swap space on disk. * When database decides to write buffer page to disk, buffer page may be in swap space, and may have to be read from swap space on disk and output to the database on disk, resulting in extra I/O! * Known as dual paging problem. * Ideally when swapping out a database buffer page, operating system should pass control to database, which in turn outputs page to database instead of to swap space (making sure to output log records first) * Dual paging can thus be avoided, but common operating systems do not support such functionality. 37. Failure with Loss of Nonvolatile Storage So far we assumed no loss of non-volatile storage * Technique similar to checkpointing used to deal with loss of non-volatile storage * Periodically dump the entire content of the database to stable storage * No transaction may be active during the dump p rocedure; a procedure similar to checkpointing must take place * Output all log records currently residing in main memory onto stable storage. * Output all buffer blocks onto the disk. * Copy the contents of the database to stable storage. * Output a record ; dump ; to log on stable storage. * To recover from disk failure * restore database from most recent dump. Consult the log and redo all transactions that committed after the dump * Can be extended to allow transactions to be active during dump; known as fuzzy dump or online dump * Will study fuzzy checkpointing later 38. Advanced Recovery Algorithm 39. Advanced Recovery Techniques * Support high-concurrency locking techniques, such as those used for B + -tree concurrency control * Operations like B + -tree insertions and deletions release locks early. * They cannot be undone by restoring old values ( physical undo ), since once a lock is released, other transactions may have updated the B + -tree. * Instead, insertions (resp. el etions) are undone by executing a deletion (resp. insertion) operation (known as logical undo ). * For such operations, undo log records should contain the undo operation to be executed * called logical undo logging , in contrast to physical undo logging . * Redo information is logged physically (that is, new value for each write) even for such operations * Logical redo is very complicated since database state on disk may not be â€Å"operation consistent† 40. Advanced Recovery Techniques (Cont. ) * Operation logging is done as follows: * When operation starts, log ; T i , O j , operation-begin ;. Here O j is a unique identifier of the operation instance. While operation is executing, normal log records with physical redo and physical undo information are logged. * When operation completes, ; T i , O j , operation-end , U; is logged, where U contains information needed to perform a logical undo information. * If crash/rollback occurs before operation completes: * the operatio n-end log record is not found, and * the physical undo information is used to undo operation. * If crash/rollback occurs after the operation completes: * the operation-end log record is found, and in this case * logical undo is performed using U ; the physical undo information for the operation is ignored. Redo of operation (after crash) still uses physical redo information . 41. Advanced Recovery Techniques (Cont. ) * Rollback of transaction T i is done as follows: * Scan the log backwards * If a log record ; T i , X, V 1 , V 2 ; is found, perform the undo and log a special redo-only log record ; T i , X, V 1 ;. * If a ; T i , O j , operation-end , U ; record is found * Rollback the operation logically using the undo information U . * Updates performed during roll back are logged just like during normal operation execution. * At the end of the operation rollback, instead of logging an operation-end record, generate a record * ; T i , O j , operation-abort ;. Skip all preceding log records for T i until the record ; T i , O j operation-begin ; is found 42. Advanced Recovery Techniques (Cont. ) * Scan the log backwards (cont. ): * If a redo-only record is found ignore it * If a ; T i , O j , operation-abort ; record is found: * skip all preceding log records for T i until the record ; T i , O j , operation-begi n; is found. * Stop the scan when the record ; T i , start; is found * Add a ; T i , abort ; record to the log * Some points to note: * Cases 3 and 4 above can occur only if the database crashes while a transaction is being rolled back. Skipping of log records as in case 4 is important to prevent multiple rollback of the same operation. 43. Advanced Recovery Techniques(Cont,) * The following actions are taken when recovering from system crash * Scan log forward from last ; checkpoint L ; record * Repeat history by physically redoing all updates of all transactions, * Create an undo-list during the scan as follows * undo-list is set to L initially * Whene ver ; T i start ; is found T i is added to undo-list * Whenever ; T i commit ; or ; T i abort ; is found, T i is deleted from undo-list * This brings database to state as of crash, with committed as well as uncommitted transactions having been redone. Now undo-list contains transactions that are incomplete , that is, have neither committed nor been fully rolled back. 44. Advanced Recovery Techniques (Cont. ) * Recovery from system crash (cont. ) * Scan log backwards, performing undo on log records of transactions found in undo-list . * Transactions are rolled back as described earlier. * When ; T i start ; is found for a transaction T i in undo-list , write a ; T i abort ; log record. * Stop scan when ; T i start ; records have been found for all T i in undo-list * This undoes the effects of incomplete transactions (those with neither commit nor abort log records). Recovery is now complete. 45. Advanced Recovery Techniques (Cont. ) * Checkpointing is done as follows: Output all log records in memory to stable storage * Output to disk all modified buffer blocks * Output to log on stable storage a ; checkpoint L ; record. * Transactions are not allowed to perform any actions while checkpointing is in progress. * Fuzzy checkpointing allows transactions to progress while the most time consuming parts of checkpointing are in progress * Performed as described on next slide 46. Advanced Recovery Techniques (Cont. ) * Fuzzy checkpointing is done as follows: * Temporarily stop all updates by transactions * Write a ; checkpoint L ; log record and force log to stable storage * Note list M of modified buffer blocks Now permit transactions to proceed with their actions * Output to disk all modified buffer blocks in list M * blocks should not be updated while being output * Follow WAL: all log records pertaining to a block must be output before the block is output * Store a pointer to the checkpoint record in a fixed position last _ checkpoint on disk * When recovering usin g a fuzzy checkpoint, start scan from the checkpoint record pointed to by last _ checkpoint * Log records before last _ checkpoint have their updates reflected in database on disk, and need not be redone. * Incomplete checkpoints, where system had crashed while performing checkpoint, are handled safely 47. ARIES Recovery Algorithm 48. ARIES * ARIES is a state of the art recovery method * Incorporates numerous optimizations to reduce overheads during normal processing and to speed up recovery * The â€Å"advanced recovery algorithm† we studied earlier is modeled after ARIES, but greatly simplified by removing optimizations * Unlike the advanced recovery lgorithm, ARIES * Uses log sequence number (LSN) to identify log records * Stores LSNs in pages to identify what updates have already been applied to a database page * Physiological redo * Dirty page table to avoid unnecessary redos during recovery * Fuzzy checkpointing that only records information about dirty pages, and does not require dirty pages to be written out at checkpoint time * More coming up on each of the above †¦ 49. ARIES Optimizations * Physiological redo * Affected page is physically identified, action within page can be logical * Used to reduce logging overheads * e. g. hen a record is deleted and all other records have to be moved to fill hole * Physiological redo can log just the record deletion * Physical redo would require logging of old and new values for much of the page * Requires page to be output to disk atomically * Easy to achieve with hardware RAID, also supported by some disk systems * Incomplete page output can be detected by checksum techniques, * But extra actions are required for recovery * Treated as a media failure 50. ARIES Data Structures * Log sequence number (LSN) identifies each log record * Must be sequentially increasing * Typically an offset from beginning of log file to allow fast access * Easily extended to handle multiple log files Each page contains a PageLSN which is the LSN of the last log record whose effects are reflected on the page * To update a page: * X-latch the pag, and write the log record * Update the page * Record the LSN of the log record in PageLSN * Unlock page * Page flush to disk S-latches page * Thus page state on disk is operation consistent * Required to support physiological redo * PageLSN is used during recovery to prevent repeated redo * Thus ensuring idempotence 51. ARIES Data Structures (Cont. ) * Each log record contains LSN of previous log record of the same transaction * LSN in log record may be implicit Special redo-only log record called compensation log record (CLR) used to log actions taken during recovery that never need to be undone * Also serve the role of operation-abort log records used in advanced recovery algorithm * Have a field UndoNextLSN to note next (earlier) record to be undone * Records in between would have already been undone * Required to avoid repeated undo of already undone acti ons LSN TransId PrevLSN RedoInfo UndoInfo LSN TransID UndoNextLSN RedoInfo 52. ARIES Data Structures (Cont. ) * DirtyPageTable * List of pages in the buffer that have been updated * Contains, for each such page * PageLSN of the page RecLSN is an LSN such that log records before this LSN have already been applied to the page version on disk * Set to current end of log when a page is inserted into dirty page table (just before being updated) * Recorded in checkpoints, helps to minimize redo work * Checkpoint log record * Contains: * DirtyPageTable and list of active transactions * For each active transaction, LastLSN, the LSN of the last log record written by the transaction * Fixed position on disk notes LSN of last completed checkpoint log record 53. ARIES Recovery Algorithm * ARIES recovery involves three passes * Analysis pass : Determines Which transactions to undo * Which pages were dirty (disk version not up to date) at time of crash * RedoLSN : LSN from which redo should start * Redo pass : * Repeats history, redoing all actions from RedoLSN * RecLSN and PageLSNs are used to avoid redoing actions already reflected on page * Undo pass : * Rolls back all incomplete transactions * Transactions whose abort was complete earlier are not undone * Key idea: no need to undo these transactions: earlier undo actions were logged, and are redone as required 54. ARIES Recovery: Analysis * Analysis pass * Starts from last complete checkpoint log record Reads in DirtyPageTable from log record * Sets RedoLSN = min of RecLSNs of all pages in DirtyPageTable * In case no pages are dirty, RedoLSN = checkpoint record’s LSN * Sets undo-list = list of transactions in checkpoint log record * Reads LSN of last log record for each transaction in undo-list from checkpoint log record * Scans forward from checkpoint * .. On next page †¦ 55. ARIES Recovery: Analysis (Cont. ) * Analysis pass (cont. ) * Scans forward from checkpoint * If any log record found for transaction not in undo-list, adds transaction to undo-list * Whenever an update log record is found If page is not in DirtyPageTable, it is added with RecLSN set to LSN of the update log record * If transaction end log record found, delete transaction from undo-list * Keeps track of last log record for each transaction in undo-list * May be needed for later undo * At end of analysis pass: * RedoLSN determines where to start redo pass * RecLSN for each page in DirtyPageTable used to minimize redo work * All transactions in undo-list need to be rolled back 56. ARIES Redo Pass * Redo Pass: Repeats history by replaying every action not already reflected in the page on disk, as follows: * Scans forward from RedoLSN. Whenever an update log record is found: * If the page is not in DirtyPageTable or the LSN of the log record is less than the RecLSN of the page in DirtyPageTable, then skip the log record * Otherwise fetch the page from disk.If the PageLSN of the page fetched from disk is less than the LSN of the log record, redo the log record * NOTE: if either test is negative the effects of the log record have already appeared on the page. First test avoids even fetching the page from disk! 57. ARIES Undo Actions * When an undo is performed for an update log record * Generate a CLR containing the undo action performed (actions performed during undo are logged physicaly or physiologically). * CLR for record n noted as n ’ in figure below * Set UndoNextLSN of the CLR to the PrevLSN value of the update log record * Arrows indicate UndoNextLSN value * ARIES supports partial rollback * Used e. g. o handle deadlocks by rolling back just enough to release reqd. locks * Figure indicates forward actions after partial rollbacks * records 3 and 4 initially, later 5 and 6, then full rollback 1 2 3 4 4†² 3†² 5 6 5†² 2†² 1†² 6†² 58. ARIES: Undo Pass * Undo pass * Performs backward scan on log undoing all transaction in undo-list * Backward scan optimized by skipping unneeded log records as follows: * Next LSN to be undone for each transaction set to LSN of last log record for transaction found by analysis pass. * At each step pick largest of these LSNs to undo, skip back to it and undo it * After undoing a log record For ordinary log records, set next LSN to be undone for transaction to PrevLSN noted in the log record * For compensation log records (CLRs) set next LSN to be undo to UndoNextLSN noted in the log record * All intervening records are skipped since they would have been undo already * Undos performed as described earlier 59. Other ARIES Features * Recovery Independence * Pages can be recovered independently of others * E. g. if some disk pages fail they can be recovered from a backup while other pages are being used * Savepoints: * Transactions can record savepoints and roll back to a savepoint * Useful for complex transactions Also used to rollback just enough to release locks on deadlock 60. Other ARIES Features (Cont. ) * Fine-grained locking: * Index concurrency algorithms that permit tuple level locking on indices can be used * These require logical undo, rather than physical undo, as in advanced recovery algorithm * Recovery optimizations: For example: * Dirty page table can be used to prefetch pages during redo * Out of order redo is possible: * redo can be postponed on a page being fetched from disk, and performed when page is fetched. * Meanwhile other log records can continue to be processed 61. Remote Backup Systems 62. Remote Backup Systems Remote backup systems provide high availability by allowing transaction processing to continue even if the primary site is destroyed. 63. Remote Backup Systems (Cont. ) * Detection of failure : Backup site must detect when primary site has failed * to distinguish primary site failure from link failure maintain several communication links between the primary and the remote backup. * Transfer of control : * To take over control backup site first perform recovery using its copy of the database and all the long records it has received from the primary. * Thus, completed transactions are redone and incomplete transactions are rolled back. When the backup site takes over processing it becomes the new primary * To transfer control back to old primary when it recovers, old primary must receive redo logs from the old backup and apply all updates locally. 64. Remote Backup Systems (Cont. ) * Time to recover : To reduce delay in takeover, backup site periodically proceses the redo log records (in effect, performing recovery from previous database state), performs a checkpoint, and can then delete earlier parts of the log. * Hot-Spare configuration permits very fast takeover: * Backup continually processes redo log record as they arrive, applying the updates locally. When failure of the primary is detected the backup rolls back incomplete transactions, and is ready to process new transactions. * Alternative to remote backup: distributed dat abase with replicated data * Remote backup is faster and cheaper, but less tolerant to failure * more on this in Chapter 19 65. Remote Backup Systems (Cont. ) * Ensure durability of updates by delaying transaction commit until update is logged at backup; avoid this delay by permitting lower degrees of durability. * One-safe: commit as soon as transaction’s commit log record is written at primary * Problem: updates may not arrive at backup before it takes over. Two-very-safe: commit when transaction’s commit log record is written at primary and backup * Reduces availability since transactions cannot commit if either site fails. * Two-safe: proceed as in two-very-safe if both primary and backup are active. If only the primary is active, the transaction commits as soon as is commit log record is written at the primary. * Better availability than two-very-safe; avoids problem of lost transactions in one-safe. 66. End of Chapter 67. Block Storage Operations 68. Portion of t he Database Log Corresponding to T 0 and T 1 69. State of the Log and Database Corresponding to T 0 and T 1 70. Portion of the System Log Corresponding to T 0 and T 1 71. State of System Log and Database Corresponding to T 0 and T 1