Ammonium Nitrate Facts and Uses

Ammonium Nitrate Facts and Uses Ammonium nitrate is the nitrate salt of the ammonium cation. It may be considered the ammonium analog to potassium nitrate or saltpeter. Its chemical formula is NH4NO3  or N2H4O3.  In pure form, ammonium nitrate is a crystalline white solid that readily dissolves in water. Heat or ignition readily cause the substance to ignite or explode. Ammonium nitrate is not considered toxic. Options for Obtaining Ammonium Nitrate Ammonium nitrate may be purchased  as a pure chemical or  collected from instant cold packs or some fertilizers.  The compound is most commonly prepared by reacting nitric acid and ammonia. Its also possible to prepare ammonium nitrate from common household chemicals. While it is not difficult to make ammonium nitrate, it is dangerous to do so as the chemicals involved can be hazardous. In addition, it can easily become explosive when mixed with fuels or other chemicals. Ammonium Nitrate Uses and Sources Ammonium nitrate is a chemical compound used in agriculture as a fertilizer, to make pyrotechnics, as an ingredient in cold packs, and for science demonstrations. Its also used to create controlled explosions in mining and quarrying. It was once mined as a natural mineral (niter) in the deserts of Chile, but it is no longer available except as a man-made compound. Because ammonium nitrate may be misused, it has been phased out in many countries.

Ptolemys Contributions to Geography

Ptolemys Contributions to Geography Not much is known about the life of the Roman scholar Claudius Ptolemaeus who is more commonly known as Ptolemy. However, he was estimated to have lived from approximately 90 to 170 CE and worked in the library at Alexandria from 127 to 150.   Ptolemys Theories and Scholarly Works on Geography Ptolemy is known for his three scholarly works: the  Almagest- which focused on astronomy and geometry, the  Tetrabiblos- which focused on astrology, and, most importantly, Geography- which advanced geographic knowledge. Geography consisted of eight volumes. The first discussed the problems of representing a spherical earth on a flat sheet of paper (remember, ancient Greek and Roman scholars knew the earth was round) and provided information about map projections. The second through seventh volumes of the work was a gazetteer of sorts, as a collection of eight thousand places around the world. This gazetteer was remarkable for Ptolemy invented latitude and longitude- he was the first to place a grid system on a map and use the same grid system for the entire planet. His collection of place names and their coordinates reveals the geographic knowledge of the Roman empire in the second century. The final volume of Geography was Ptolemys atlas,  featuring maps that utilized his grid system and maps that placed north at the top of the map, a cartographic convention that Ptolemy created. Unfortunately, his gazetteer and maps contained a great number of errors due to the simple fact that Ptolemy was forced to rely upon the best estimates of merchant travelers (who were incapable of accurately measuring longitude at the time). Like much knowledge of the ancient era, the awesome work of Ptolemy was lost for over a thousand years after it was first published. Finally, in the early fifteenth century, his work was rediscovered and translated into Latin, the language of the educated populace. Geography gained rapid popularity, and there were more than forty editions printed from the fifteenth through sixteenth centuries. For hundreds of years, unscrupulous cartographers of the middle ages printed a variety of atlases with the name Ptolemy on them, to provide credentials for their books. Ptolemy erroneously assumed a short circumference of the earth, which ended up convincing Christopher Columbus that he could reach Asia by sailing west from Europe. Additionally, Ptolemy showed the Indian Ocean as a large inland sea, bordered on the south by Terra Incognita (unknown land). The idea of a large southern continent sparked countless expeditions. Geography had a profound effect on the geographical understanding of the world in the Renaissance and it was fortunate that its knowledge was rediscovered to help establish geographical concepts that we almost take for granted today. Note that the scholar Ptolemy is not the same as the Ptolemy who governed Egypt and lived from 372-283 BCE. Ptolemy was a common name.

How effective was Khrushchevs religious policy Essay

How effective was Khrushchevs religious policy - Essay Example x Church that offered support for the war effort; in return Stalin â€Å"promised them a new deal involving the return of some churches and other institutions, a limited right of publication, and the freeing of such religious personnel as had survived the terror of the 1930s and earlier† (Anderson 1994, p. 8). Consequently, the number of registered religious communities increased considerably after the war and within no time the influence of the church posed a great threat to the state’s autonomy. It was at this juncture that a full-scale persecution of religion began in the nation under the leadership of Khrushchev who became the undisputed leader of the party and government after Malenkov retired in 1959 (Pospielovsky 1998, p. 313). This paper seeks to make a probe into the religious policy of Khrushchev and how far his policies have been effective in attaining their goals. Khrushchev adorns the place of a radical reformer and liberalist in the history of Soviet Union; despite his anti-religious policies one can never undermine his initiatives to bring about a ‘considerable degree of liberalization in many other areas of Soviet life’ and there are many who think that his assault on religion stemmed from a ‘personal commitment to the building of a communist society within the foreseeable future’ (Anderson 1994, p. 7). For Chumachenko & Roslof (2002, p. 148), Khrushchev was in a way distancing himself from church problems until the end of the 1950s and that â€Å"issues of church policy originally did not have any fixed place in his grandiose plans for reconstructing and altering Soviet society†. However, Khrushchev later turned vehemently against the Russian church as he believed that the disappearance of religion was an essential prerequisite for the creation of a total communist society. As a liberalist, Khrushchev des cribed himself as an atheist and an advocate of the scientific world view; he held that â€Å"education, scientific knowledge and the study

Creating Academic and Professional Success Essay - 1

Creating Academic and Professional Success - Essay Example A team is a collection of individuals that have unique talents and expertise. As a team they are able to exploit and share the knowledge that they possess. A team is able to assign a task to the most applicable member of the team and in doing so it makes the most advantageous use of their resources. This also allows the team members some flexibility in their role as a team member. In addition, the team allows management to assign workflow as needed. Teams can be assembled for a short period of time on an as needed basis. Teams also have the advantage of sharing a common goal. When the group shares the common goal, all work and resources are devoted to reaching the goal. This reduces redundancy and ambiguity among the workforce and makes the best use of their time. It further allows the team to direct their attention to complex problem solving as a group that an individual may not be able to accomplish. This interjects more creativity and flexibility into the workflow process. While there are many advantages, it must be remembered that teams must have the appropriate communication skills to be able to take advantage of the team structure. When using a team for decision making, the group may be guided by group-think or extreme positions advocated by powerful members. This is a major challenge to overcome to assure all team members have an equal input. Another challenge to a team is the acceptance, by its members, that responsibility and rewards are shared equally. This may face difficulties in introducing the team concept where the organizational culture is ingrained with a task oriented and individual concept. The team may have loafers that assume they can slack off and spread the responsibility out among the other members. Miscommunication or cultural differences that are misunderstood can also challenge the team. The team will be challenged to work to overcome these problems as the team matures. For Chris to deal with stress

My High School Years Essay Example for Free

My High School Years Essay We all have nice memories of when we attended high school. Memories that will never be forgotten. For most of us it has been a while since high school and it is all a blur. We all remember a lot of things, especially things that the school did and we didn’t approve of. Something that would annoy us, but we wouldn’t be able to do anything about it. The majority of us, I’m sure, don’t like the way the school handled the schedule, the food we had for lunch, or the teachers we had to listen to. One of the things that they need to change in high school is the way they handle the lunch periods. School is already hard on us because of all the homework we get and I don’t think is fair that they won’t allow us to pick our lunch period. We are all accustomed to eating at a certain time. The school would either give us lunch too early or too late. If they gave us lunch too early, we wouldn’t be hungry. In my case I would have breakfast during my study hall which was 3rd period, then I would have lunch which was 4rd period. I would have to force myself to eat or else I would be hungry the rest of the day. If we had lunch too late, we would not be able to concentrate in class because while we were working silently on our work we could hear our stomach growling, students that were sitting around us would just laugh. I remember that when that would happen to me I would start turning the pages of my book real fast so that the students around me couldn’t hear me. When I was in high school most of the students were mean and unfriendly. It was really hard to make friends, at least for me it was, and to be placed in a lunch period where you didn’t know anyone wasn’t easy. Our high school had a big cafeteria that could be divided into three smaller rooms, but they would never open up the walls. The reason for this was that there had been a huge fight once and they didn’t want any more confrontations. Each room had a name, they were named Commons A, Commons B, and Commons C. We weren’t able to pick the common in which we wanted to be in. The school, to make our life more miserable, would also give us assigned seats. One thing that I can’t complain about and that my classmates are probably going to look at me right now for saying this is the food. I went to Belvidere High School and I loved the food! I would look forward to lunchtime every day just because of the food. Till this day I have not found alfredo sauce that is as good as the one that they just to give us in high school. One thing that I would hate in high school was how they would run the schedules. They would give us too much time for one thing and not enough for another. We would go into a classroom for 15 minutes and do nothing. This class period was called home room. The teacher was supposed to inform us of changes that would be going on around the school, but they never would. We would sit there for 15 minutes of our life and basically do nothing. The teacher herself didn’t know what was going on. They also need to take away study hall, people didn’t do their homework during study hall. They would just sit there and talk, they wouldn’t even bring their books to study hall. Instead of getting study hall we should get more gym time. I mean, 45 minutes isn’t enough to actually exercise. By the time that we are done getting dressed we only have about 35 minutes left. Then the teachers instead of hurrying up the students, they’re over there having conversations with the other gym teachers . Then they take forever to take attendance. By then time they’re done explaining what were actually doing that day, we have like 25 minutes left of gym, not including the 5 minutes they give us at the end of the class period to get changed. 20 minutes is not enough time to run a gym class. We can’t exercise, sweat and take a shower in that little time and then the media complains that the students are obese. The method that some teachers have of teaching is absolutely awful. My Spanish teacher for native speakers was really nice and got along with everyone. All the students would talk so well about her, they would always say positive things about her. Probably because they never did anything while they were in her class. The only thing was that she was horrible at teaching. Well, it wasn’t that she was horrible at it, it was just that she wouldn’t teach anything. I remember she got sick and was out for three months. During that time we literally did not do anything. I remember that the substitute would just look at us and he would ask us what would we usually do, we would look at him, smile and answer â€Å"nothing†. Don’t ask why, but this was the second year that I had taken Spanish class with her, so when she came back she told us that most of us had been with her for two years so she would give us a grade based on what we had gotten the year before. I took that class to improve my writing in Spanish, to learn the proper grammar, but I did not achieve any of that. The English teachers weren’t as bad as the Spanish teacher, but we still didn’t accomplish much. The only time that I remember writing an essay in high school was junior year. Maybe it had to do with the school that I was in. My junior year of high school I went to Belvidere High School instead of Elgin High School. In Belvidere High the teachers were a little more strict, at least that’s what I thought. Until I found out that the only teacher that had ever assigned me to do an essay had been with one of the students. I was completely shocked because she had always been very professional about her job. Even though there’s a lot of negatives things with the high school that I went to, I still enjoyed every minute of it. I got to meet new people and experience new things. Sure my high school wasn’t the best, but I am still thankful that I received a basic education. The only thing that I do regret is not going to prom. I told myself that if no one asked me to prom that I wouldn’t go. Nobody ended up asking me so I didn’t go. I lost the chance to experience something that you only get to experience once in your life. So enjoy your high school while you can because once you are out, there is no turning back.

Should The Harris Superquarry Go Ahead? :: essays research papers

Should The Harris Superquarry Go Ahead? TABLE OF FIGURES FIGURE 1 LOCATION OF THE SUPERQUARRY  Ã‚  Ã‚  Ã‚  Ã‚  3 1 SUMMARY There is considerable environmental opposition to the development of the Harris superquarry. This is unlikely to stop the development on its own, but if the Scottish Office decides that the project can go ahead environmental restrictions are likely to be imposed on the operation to minimise, as far as possible, the impact. The reasons for the development centre round the need for economic development to bring jobs and prosperity to this remote area. The life of the quarry is expected to be around 60 years and provide an initial 30 jobs, rising to 80 as the quarry reaches peak production. The question is if a superquarry is the best solution to the problems of a remote rural area. What will happen when the jobs come to an end and would another form of investment not be more appropriate to their needs? Would the presence of a quarry restrict the choice for further development? Could an integrated approach be adopted and a 2nd generation quarry planned? The decision of whether or not to go ahead cannot be delayed indefinitely as Norway and Spain are looking at developing their own. If it is to go ahead then an early start will give Harris a stronger position in the market. 2 INTRODUCTION This report examines the controversy and key issues surrounding the superquarry at Rodel, Lingerbay on the southern coast of the Isle of Harris (Figure 1) and attempts to find an acceptable solution. The quarry will hollow out the heart of the mountain but leave enough of a shell to leave the skyline largely unaffected. The whole question of whether or not it should go ahead or not is the subject of the current public enquiry in Stornaway. A decision must be made soon. The market for aggregates is limited, Norway and Spain (Section 3.1, 1991) have their own sites and are also looking at the potential for developing them. FIGURE 1 LOCATION OF THE SUPERQUARRY   Ã‚  Ã‚  Ã‚  Ã‚  (Glasgow Herald, 20/10/94) 3 THE ISSUES SURROUNDING THE DEBATE 3.1 History 1927  Ã‚  Ã‚  Ã‚  Ã‚  A detailed geological survey identified the deposit of anorthosite. 1965  Ã‚  Ã‚  Ã‚  Ã‚  Planning permission was given in principle to quarry the rock. The remit covered a larger site than is planned today. 1966  Ã‚  Ã‚  Ã‚  Ã‚  Some small scale quarrying took place but found an on site rock crushing plant and a deep harbour were necessary for economic viability. 74-76  Ã‚  Ã‚  Ã‚  Ã‚  Outline planning permission was given for quarrying, shipping and loading facilities but this was never acted on. 1977  Ã‚  Ã‚  Ã‚  Ã‚  The Scottish Office issued National Planning Guidelines. Harris was identified as one of 9 potential sites. (The Scotsman 18/7/93)

African Corruption Essay

This study intends to clearly show the extent to which Africa and Africans have been suffering from the ravages of corruption, fraud, and intentional mismanagement by their governments and their leaders, much to the disappointment and anger of the people. The impact of corruption on the lives of the people, the businesses, and the economy of any of the nations concerned has been studied by a number of authors, scholars, and worldwide institutions such as the World Bank, the IMF, and even donors (highly industrialized nations). Although Africa has a large share of the worlds raw material and mineral resources, African nations are by far the least developed and the poorest countries in the world. Robert Harris, in his book, Political Corruption In and Beyond the Nation State, (1990, p. 29,) introduced three themes. First, political corruption is an illegitimate extension of normal political activity. In trying to understand the central issue of corruption, one needs to understand the complex and intricate nature of corruption. If we ask, what is â€Å"corruption†? The American Heritage English Language Dictionary (Pickett, 2000) defines corruption as â€Å"the art or process of corruption, the state of being corrupt, decay, and rot.† As indicated above, corruption comes in many forms. In the least developed countries (LDC’s) such as Africa, all types of corruption are prevalent. The following brief case histories of these three companies will present the magnitude of the scandals, corruption, and deceit these companies perpetrated on the unsuspecting public and their business partners. Other countries of the world have similar problems of corruption, fraud, and mismanagement. From time to time, stories appear about the corruption trial of a government official, a banker, or corporate head in other parts of the world. Doing Business in Africa and Other Non-Industrialized Nations, the basic tenets of the guiding principles are that corruption, dishonesty, and unethical behavior among public officials represent serious threats to the basic principles and values of government, undermining public confidence in democracy and threatening to erode the rule of law. The aim of these guiding principles is to promote public trust in the integrity of officials within the public sector by preventing, detecting, and prosecuting or sanctioning official corruption and unlawful dishonest or unethical behavior. Monsanto Co.: Settled an SEC complaint in January alleging that the company funneled more than $700,000 in corrupt payments to Indonesian government officials between 1997 and 2002. ExonMobil, Chevron Texaco, Marathon Oil, Devon Energy, and Amerada Hess, as well as several other oil companies: These reportedly are involved in SEC investigations into bribes allegedly paid to government officials in Equatorial Guinea. Public perception of police corruption stems mainly from instances where the public has come face to face with the vice as they interact with police in their discharge of duty. My personal experience also left me with no doubt that police corruption in South Africa was daunting task for the new democratic government of South Africa. While police brutality in Kenya is much less compared to that of the apartheid South Africa, the police corruption in Kenya is much more widespread and open. Corruption in the police force takes various forms and in various degrees of sophistication. Corruption in Kenya and more particularly among the police has reached unprecedented levels. Thieves have been set free from police cells because of corruption. The ministry of public works: This is the second most corrupt institution in Kenya. Finding found that this is the Ministry that has the highest rent corruption in Kenya. A large population of the Kenyan people expressed disgust at the corruption in this ministry. The corruption at the ministry of public works is more sophisticated than meets the eye. It is also in charge of construction of government residential houses and offices. The ministry houses the largest number of government employed Engineers, professionals, and Architects. It is actually a key ministry in any government.   Millions of shillings are spent in purchasing goods and services for the government. There was no good will from the establishment to deal with cases of corruption. Where genuine outside companies have been awarded contracts, big bribes were paid to the committee before the award. In one case a contractor has given a job to put up some government circles. The author discovered that this was done just to get free money as penalties from the government. The poor jobs that we have seen on our roads are a result of corruption. This makes the land law in Kenya, one of the most complicated land systems in the world. The Crown Lands Ordinance (Cap. 280) passed in 1915 defined crown land as â€Å"All public land including all land occupied by the native tribes of the protectorate and all land reserved for the use of the members of any native tribe.† All the land rights of the natives were ignored. After all and without exception, African customs recognized land rights. African communities saw land as a gift of God to every individual. That has been the root cause of land problems in this country. Nowhere in Africa is land such expensive commodity as it is in Kenya. A Kenyan who has no land will always work hard to buy himself land. Land and Corruption in Africa The Ministry of Lands is one of the most corrupt institutions in this country. Land Cartels Land allocations, is the biggest single activity that goes on at the Lands office, Nairobi. Here, the people of Kenya will spend as much time and spend as much money, to ensure that they have been allocated land. Income tax department: African Revenue Authority is the main government agency for collecting all government revenue. No government can run on its own without taxes. Money collected from taxes is what the government uses to provide public services like Education, Health, Infrastructure, security and policing, a forestation, public service employment, defence and many others. (Transparency International Report, 2006) You cannot tax people so highly and yet fail to provide services. Over Kenya Shillings 250 billion taxes, (Transparency International Report, 2006), are collected annually by the Kenya Revenue Authority. The African revenue authority has some of the best professionals in the public service. Corruption at the African Revenue Authority is a matter of great concern. There is corruption in the organization both corporate and individual taxpayers. With the present economic situation most business people are stressed out and depressed. Research revealed that there is massive corruption in the import and export sector. Tax evasion is very high in this sector and the government loses millions of shillings through fraud and tax evasion. It was found that tax officers collude with importers and exporters to avoid tax and deny the government the badly needed revenue. This area has provided a good breeding ground for corruption in the income tax department. Officers in the Revenue Authority come across these businesses every day. The government is losing a lot of revenue by leaving these sectors out.

Guidelines For Assignment

Define Organizational Culture What Is meant by Organizational Culture? Characteristics of Organizational Culture ? Positive (good) and Negative (bad) Provide relevant examples Research can be done by referring to similar researches that were conducted previously. The sources of references can be obtained from books, Journals, magazines or newspapers. Related research materials such as graphs, charts or pictures can also be used to support a statement. Students are also encouraged to give their opinions and their own understanding of the research topic.Provide examples of outcomes from previous researches (done by another searcher) regarding topics that are similar or almost similar. – relationship between Organizational Culture and the success or failure of an organization. Gather the information needed from books, magazines, newspapers or Journals relevant to the topic being discussed. From the gathered information, identify how elements of Organizational Culture affect the s uccess or failure of an organization. Provide examples. 1 State the outcome of the research based on the gathered Information.Relate between the theories learned with the real situation. Is It true Organizational Culture Is a factor that determines the success and failure of an organization? Yes or No Provide a conclusion from the overall research and give your suggestions for the development of a better Organizational Culture to enhance the success of the organization. Format for preparing the assignment: Paper Use Ã'›white-bond† quality paper Paper size : AAA (210 mm x 297 mm) Paper weight : 80 MGM Method of typing The text should be typed on one side of the page only.For text : black-colored ribbon or ink cartridge that produces an even black color. For diagrams, tables and charts : black or colored ink. Line Spacing For text : double-spacing For references (refer vii), appendices and tables: single-spacing Font Times New Roman Size: 12 2 Margin Left margin : at least 4. 0 CM (1. 5†³) Top, bottom and right margin : 2. 5 CM (1. 0†³) Section New major sections must begin on a new page. A new paragraph must begin with a Ã'›tab† from the left margin. V) Page numbering Excerpts, references, appendices and tables a) In the text.If an excerpt is taken from a reference material, the reference must be stated. Ex : Stoner and Yankee define strategy as, â€Å"†¦ The broad program for defining and achieving an organization†s objectives; the organization†s response to its environment over time. † (Stoner and Yankee, 1986) b) List of References At the end of the assignments, all references or bibliography must be stated in alphabetical order according to the name of the author. Book:Name of author.

Free Essays on Media Literacy

Despite numerous attempts to introduce a formal media education policy into all U.S. Public schools, is has not been officially accepted as a part of the general curriculum. Only handfuls of school across the country offer the option to choose courses in media literacy, and choosing the course in the first place is the students discretion. However, media education policies have been extremely effective in countries such as Norway, and our neighbors to the North, Canada. One fundamental difference as to why media literacy policies and education programs have been in effect in those countries and not the United States is because the United states has a decentralized education system; Norway and Canada both have centralized systems. Change of curricula comes about much easier in the centralized systems, while it is much more difficult in decentralized school systems. The policy in Canada requires that 30% of all high school students language arts credits be taken in the subject of Media Literacy and Education. However, New Mexico was one of the first states to implement a mandatory media literacy requirement. The New Mexico Media Literacy Project, or NMMLP, was created in 1993 as an outreach of Alberquerque Academy, one of the best private schools (grades 6-12) in the United States. The program that they have developed is used by thousands of schools across several states, with their main goal being â€Å"†¦ to make New Mexico the most media literate state in the United States, and to spread the NMMLP model of grassroots, action-oriented media literacy education to other states.† The NMMLP provides in-service training for public and private school teachers, counselors, principals and administrators. They also hold four-day workshops three to four times a year. The American Association of Pediatrics has also released its suggested policy on children and media literacy. Published in PEDIATRICS Vol. 108 No. 5, November 2001, pp. 1222-12... Free Essays on Media Literacy Free Essays on Media Literacy Despite numerous attempts to introduce a formal media education policy into all U.S. Public schools, is has not been officially accepted as a part of the general curriculum. Only handfuls of school across the country offer the option to choose courses in media literacy, and choosing the course in the first place is the students discretion. However, media education policies have been extremely effective in countries such as Norway, and our neighbors to the North, Canada. One fundamental difference as to why media literacy policies and education programs have been in effect in those countries and not the United States is because the United states has a decentralized education system; Norway and Canada both have centralized systems. Change of curricula comes about much easier in the centralized systems, while it is much more difficult in decentralized school systems. The policy in Canada requires that 30% of all high school students language arts credits be taken in the subject of Media Literacy and Education. However, New Mexico was one of the first states to implement a mandatory media literacy requirement. The New Mexico Media Literacy Project, or NMMLP, was created in 1993 as an outreach of Alberquerque Academy, one of the best private schools (grades 6-12) in the United States. The program that they have developed is used by thousands of schools across several states, with their main goal being â€Å"†¦ to make New Mexico the most media literate state in the United States, and to spread the NMMLP model of grassroots, action-oriented media literacy education to other states.† The NMMLP provides in-service training for public and private school teachers, counselors, principals and administrators. They also hold four-day workshops three to four times a year. The American Association of Pediatrics has also released its suggested policy on children and media literacy. Published in PEDIATRICS Vol. 108 No. 5, November 2001, pp. 1222-12...

4 Types of Hypersensitivity Reactions

4 Types of Hypersensitivity Reactions Our immune system works continuously to keep us healthy and protect us against bacteria, viruses, and other germs. Sometimes, however, this system becomes too sensitive, causing hypersensitivity reactions that can be harmful or even deadly. These reactions are the result of exposure to some type of foreign antigen either on or in the body. Hypersensitivity Reactions Key Takeaways Hypersensitivity reactions are exaggerated immune responses to allergens.There are four types of hypersensitivity reactions. Types I through III are mediated by antibodies, while type IV is mediated by T cell lymphocytes.Type I hypersensitivities involve IgE antibodies that initially sensitize an individual to an allergen and provoke a quick inflammatory response upon subsequent exposure. Allergies and hay fever are both type I.Type II hypersensitivities involve the binding of IgG and IgM antibodies to antigens on cell surfaces. This induces a cascade of events that leads to cell death. Hemolytic transfusion reactions and hemolytic disease of newborns are type II reactions.Type III hypersensitivities result from the formation of antigen-antibody complexes that settle on tissues and organs. In an attempt to remove these complexes, underlying tissue is also damaged. Serum sickness and rheumatoid arthritis are examples of type III reactions.Type IV hypersensitivities are regulated by T cells and are delayed reactions to antigens associated with cells. Tuberculin reactions, chronic asthma, and contact dermatitis are examples of type IV reactions. Hypersensitivity reactions are categorized into four major types: type I, type II, type III, and type IV. Type I, II, and III reactions are the result of antibody actions, while type IV reactions involve T cell lymphocytes and cell-mediated immune responses. Type I Hypersensitivity Reactions This image is depicting hay fever showing pollen grains (yellow) entering the nasal cavity (left) of a hay fever sufferer. The symptoms are caused by a massive release of the chemical histamine in the body in response to the pollen. Claus Lunau/Science Photo Library/Getty Images Type I hypersensitivities are immune reactions to allergens. Allergens can be anything (pollen, mold, peanuts, medicine, etc.) that triggers an allergic reaction in some individuals. These same allergens do not normally cause problems in most individuals. Type I reactions involve two types of white blood cells (mast cells and basophils), as well as immunoglobulin E (IgE) antibodies. Upon the initial exposure to an allergen, the immune system produces IgE antibodies which bind to the cell membranes of mast cells and basophils. The antibodies are specific to a particular allergen and serve to detect the allergen upon subsequent exposure. A second exposure results in a rapid immune response as IgE antibodies attached to mast cells and basophils bind allergens and initiate degranulation in the white blood cells. During degranulation, mast cells or basophils release granules that contain inflammatory molecules. The actions of such molecules (heparin, histamine, and serotonin) result in allergy symptoms: runny nose, watery eyes, hives, coughing, and wheezing. Allergies can range from mild hay fever to life-threatening anaphylaxis. Anaphylaxis is a serious condition, resulting from inflammation caused by histamine release, that impacts the respiratory and circulatory systems. The systemic inflammation results in low blood pressure and blockage of air passages due to swelling of the throat and tongue. Death may occur quickly if not treated with epinephrine. Type II Hypersensitivity Reactions This image shows type A blood (A antigen) that was agglutinated (clumped) by mixing the blood with a serum containing anti-A antibody. An antigen-antibody reaction agglutinated the red blood cells forming a large clump. Ed Reschke/Photolibrary/Getty Images Type II hypersensitivities, also called cytotoxic hypersensitivities, are the result of antibody (IgG and IgM) interactions with body cells and tissues that lead to cell destruction. Once bound to a cell, the antibody initiates a cascade of events, known as complement, that causes inflammation and cell lysis. Two common type II hypersensitivities are hemolytic transfusion reactions and hemolytic disease of newborns. Hemolytic transfusion reactions involve blood transfusions with incompatible blood types. ABO blood groups are determined by the antigens on red blood cell surfaces and the antibodies present in blood plasma. A person with blood type A has A antigens on blood cells and B antibodies in blood plasma. Those with blood type B have B antigens and A antibodies. If an individual with type A blood were given a blood transfusion with type B blood, the B antibodies in the recipients plasma would bind to the B antigens on the red blood cells of the transfused blood. The B antibodies would cause the type B blood cells to clump together (agglutinate) and lyse, destroying the cells. Cell fragments from the dead cells could obstruct blood vessels leading to damage of the kidneys, lungs, and even death. Hemolytic disease of newborns is another type II hypersensitivity that involves red blood cells. In addition to A and B antigens, red blood cells may also have Rh antigens on their surfaces. If Rh antigens are present on the cell, the cell is Rh positive (Rh). If not, it is Rh negative (Rh-). Similar to ABO transfusions, incompatible transfusions with Rh factor antigens can lead to hemolytic transfusion reactions. Should Rh factor incompatibilities occur between mother and child, hemolytic disease could occur in subsequent pregnancies. In the case of an Rh- mother with an Rh child, exposure to the childs blood during the final trimester of pregnancy or during childbirth would induce an immune response in the mother. The mothers immune system would build up antibodies against the Rh antigens. If the mother became pregnant again and the second child was Rh, the mothers antibodies would bind to the babies Rh red blood cells causing them to lyse. To prevent hemolytic disease from occurring, Rh- mothers are given Rhogam injections to stop the development of antibodies against the blood of the Rh fetus. Type III Hypersensitivity Reactions Arthritis is an inflammation of the joints. This colored X-ray shows the hands of an 81 year old female patient with rheumatoid arthritis. Credit: Science Photo Library/Getty Images Type III hypersensitivities are caused by the formation of immune complexes in body tissues. Immune complexes are masses of antigens with antibodies bound to them. These antigen-antibody complexes contain greater antibody (IgG) concentrations than antigen concentrations. The small complexes can settle on tissue surfaces, where they trigger inflammatory responses. The location and size of these complexes make it difficult for phagocytic cells, like macrophages, to remove them by phagocytosis. Instead, the antigen-antibody complexes are exposed to enzymes that break down the complexes but also damage underlying tissue in the process. Immune responses to antigens of type III hypersensitivities are serum sickness (systemic inflammation caused by immune complex deposits), lupus, and rheumatoid arthritis. Type IV Hypersensitivity Reactions Contact dermatitis is a type IV hypersensitivity that results in severe skin rash. Smith Collection/Stone/Getty Images Type IV hypersensitivities do not involve antibody actions but rather T cell lymphocyte activity. These cells are involved in cell mediated immunity, a response to body cells that have become infected or carry foreign antigens. Type IV reactions are delayed reactions, as it takes some time for a response to occur. Exposure to a particular antigen on the skin or an inhaled antigen induces T cell responses that result in the production of memory T cells. Upon subsequent exposure to the antigen, memory cells induce a quicker and more forceful immune response involving macrophage activation. It is the macrophage response that damages body tissues. Type IV hypersensitivities that impact the skin include tuberculin reactions (tuberculosis skin test) and allergic reactions to latex. Chronic asthma is an example of a type IV hypersensitivity resulting from inhaled allergens. Some type IV hypersensitivities involve antigens that are associated with cells. Cytotoxic T cells are involved in these types of reactions and cause apoptosis (programmed cell death) in cells with the identified antigen. Examples of these types of hypersensitivity reactions include poison ivy induced contact dermatitis and transplant tissue rejection. Sources Hypersensitivity Reactions. Microbiology and Immunology Online.Parker, Nina, et al. Microbiology. OpenStax, Rice University, 2017.

The reasons why the British, from Parliament to the Expeditionary Essay

The reasons why the British, from Parliament to the Expeditionary Forces, were defeated by a less trained and weaker American army in the American Revolutionary - Essay Example How could a group of colonies spread out over a vast region with no central government or treasury and an army that was inadequately trained and equipped possibly defeat the British who were the most powerful military force at that time? Britain had ruled over the thirteen colonies in America for more than 200 years prior to the Revolution. By the beginning of the Revolution, the wars against France fought on both sides of the Atlantic had burdened Britain with a massive national debt. To ease the national debt, Parliament imposed taxes on the colonists believing it only fair that they bear part of the expenses incurred by the British military in protecting them from Indian attacks and French invasions. The Stamp Act taxed paper goods sent to the colonies. It was the first of these laws while, with the tea tax, was one of the most infamous of these laws. The colonists thought taxation without representation in the British government to be unjust and openly protested these laws which led to hostilities between British troops and the Massachusetts Minutemen in 1775. This and other conflicts with the ‘Red Coats’ led to colonists forming the Continental Congress which immediately created the Continental Arm y and in 1776, signed the Declaration of Independence (The American Revolution, 2006). The Americans, outmatched by more than three-to-one, were predictably defeated in the majority of battles that occurred during the war’s first year. However, the Americans’ fortune began to change following the victories at Saratoga and Germantown in 1777. These important first triumphs gave increased credibility to what had previously been widely considered as an unorganized, minor uprising certain to be vanquished by the mighty British army. By 1778, France had become convinced that Britain stood the chance of being defeated. Wanting nothing more than this,