Structure of The Major Histocompatibiltiy Complex (MHC) Essay

Structure of The Major Histocompatibiltiy Complex (MHC) - Essay Example The functions performed by the complex are: binding of peptide fragments from invading pathogens and then displaying these peptide fragments on the cell surface so that it should be recognized by T-cells fro further degradation. MHC has got two unique properties, which make it difficult for any pathogen to evade immune responses in this way. These are:i) the MHC is polygenic: there are different varieties of MHC class I and MHC class II genes, hence every individual has got a set of MHC molecules with different ranges of peptide-binding specificities.ii) the MHC is highly polymorphic; there are multiple variants of each gene within the population as a whole. The MHC genes are, in fact, the most polymorphic genes known (Janeway 2001). It has become an important and more frequent clinical practice to replace diseased organs through transplantation. The response of the body to tissues with nucleated cells is more severe, as compared to blood transfusion containing anucleated RBCs, and it is the response of T-cells to highly polymorphic MHC molecules. This can be achieved by matching of the MHC type between donor and recipient that is not possible to 100%. (Janeway 2001) Previously rejected graft from a donor decreases the probability of acceptance of the second graft from the same donor to the same recipient and this response even earlier than the first set reject when body rejects it within a week time. This is again mediated by CD8 T cells, by CD4 T cells, or by both and at times even antibodies also become a part of this team (Janeway 2001). Matching donor and recipient at the MHC When donor and recipient differ at the MHC, the immune response, which is known as an alloreactive response as it is directed against antigens (alloantigens) that differ between members of the same species, is directed at the nonself allogeneic MHC molecule or molecules present on the graft. Most tissues contain predominantly MHC class I antigens. Once a graft is rejected due to presence of a particular MHC type, the second graft with the same nonself MHC molecule will also be rejected in a second-set response in a rapid manner. This is because of the frequency of T cells specific for any nonself MHC molecule that is very high, making differences at MHC loci the most potent trigger of the rejection of initial grafts (Janeway 2001). In human, HLA matching significantly improves the success rate of clinical organ transplantation but even it cannot in itself prevent rejection reactions. There are two main reasons behind this phenomenon: a) HLA typing is imprecise, owing to the polymorphism and complexity of the

Economies of Scale Essay Example | Topics and Well Written Essays - 2500 words

Economies of Scale - Essay Example This concept is popularly known as 'Economies of Scale'. Many firms in different sectors of the economy are experiencing the economies of scale by virtue of expanding their economic activities to a greater level. The economies of scale may be internal or external. Internal economies of scale are experienced within the same firm while external economies of scale are experienced in the same industry. In this paper the internal economies of scale are discussed in detail in the Section-I. Subsequently disadvantages of the economies of scale for a firm as well as for the consumers of the firms experiencing economies of scale are described in the section-II and III. Finally the implications of the regulatory authorities on the concept of 'minimum efficient scale' has been described in section-IV. If the average cost per unit of input falls per unit increase in the output, then the firm is said to be enjoying the internal economies of scale. This in other words it can be expressed as a percentage change in all inputs leads to a greater percentage change in outputs. Here average total cost (ATC) first decreases because fixed cost such as buildings, equipments and management expenses remains constant and have been utilized to their optimum. The total cost is spread over a greater range of outputs. This increasing returns to scale is achieved till an optimum level after which any increase in the quantity of input, the average total cost(ATC) increases showing the diseconomies of scale. Firms which generally require large capital investments show economies of scale. This internal economies of scale is of five types, such as technical, commercial, managerial, financial and risk bearing economies. The pattern of the economies of scale is shown in the figure- 1. Figure-1: Various types of economies of scale (Source: http://www.bized.co.uk/educators/16-19/economics/firms/presentation/scale_map.htm ) There are various factors as shown in the figure-1 contributes to different economies of scale. Each factor has got significance for reduction in average cost of production thus making the output cheaper. Technical: Technical economies are when improved techniques benefits a firm to increase its production to a large extent. "Businesses with large scale production can use more advanced machinery (or use existing machinery more efficiently). This may include using mass production techniques, which are more efficient form of production" ( tutor2u.net). This technical economies of scale is achieved due to several factors, such as: Indivisibility of Plant:- Due to imperfect divisibility of factors the economies of scale occur and the long-run average cost falls because of this indivisibility of factors (Kaldor & Robinson, cited by Ahuza, 2004). In this case most of the factors are 'lumpy' i.e. they are available in large indivisible units which can therefore yield lower cost of production when they are used to produce a large output. Here example can be given of telecommunication industry where the initial investment in infrastructure is too high. So by increasing a larger clientele base only the fixed cost can be spread over and increasing return to scale may be seen. Likewise another example is radio-dispatching technology used by the police officers. The cost of installing the technology is about the same no

Persecution in the early church Research Paper Example | Topics and Well Written Essays - 2750 words

Persecution in the early church - Research Paper Example The Reason for Persecution Although there was no recognizable or serious offence with the early Christians professing their faith in Jesus Christ, the Roman Empire and the pagan fraternity did not bother but instead fabricated a number of allegations1. At no point did the Christian religion in the early days interfere with or distract their normal operations or peace of mind therefore one can only read mischief and ulterior motives in their quest to wipe away the early church out of existence2. Unanimously, both the pagans and the Roman Empire leveled allegations of incest, perversions, and cannibalism against their Christian counterparts3. With Emperor Nero in their lead, the persecutors insisted that their Christian brothers and sisters constantly partook of illegal and inhuman ritual and activities contrary to the acceptable norms within the Roman Empire4. Fully appreciating the government’s support, the pagans pressured the Nero, the Roman Emperor who rained from 54 AD to 64 AD, to succumb to their demands. In real sense, the good followers of Jesus Christ only practiced what they read from their respective Bibles like Baptism5. With John the Baptist as the pioneer of Baptism in water, Jesus Christ only sanctified the same through the incorporation of ‘fire’ baptism where He emphasized on the essence of involvement of the Holy Spirit6. It is by this doctrine that the early Christians based and practiced their strong beliefs, irrespective of what their ‘enemies’ thoughts and opinions. When the pagans and some officials of the Roman Emperor saw the relentless worship by the early church, they accused them of ill practices, allegation which cost most staunch Christians their lives while maiming others in the process7. Perhaps one of the most controversial reasons as to why the early church faced senseless persecution was subversion and ungodly behavior, at least according to those who strongly supported the idea of persecution. Ordinarily, the atheists and those who believed in the Roman gods united on some fronts especially those pertaining to the official religious practices as manifested by the Roman Emperor8. Occasionally, all the inhabitants of the Roman Emperor offered sacrifices to the Roman gods as a sign of gratification and honor, a practice the early church came strongly against for their own reasons. During the first century, most Romans and atheists believed that by worshipping and offering sacrifices to their gods, they would receive blessings, protections, and improve in their general wellbeing9. The early Christians on the other hand, believed in and followed strictly the teachings inscribed within the Christian Bible that fiercely condemned the worship, honor, or offering of sacrifices to the so called ‘idols’. Duly guided by this clause, these believers in Jesus Christ objected to the pleas by the vast majority of the officials of the Roman Emperor10. As if that was not enou gh, the cult extended to the honor and offering sacrifices to the Roman Emperors, fully acknowledging the fact that they were sanctified monarchs, who deserved equal and undivided attention as other gods11. The successive Roman Emperors highly encouraged this trend as it they felt that it boosted their ego besides elevating them above normal human beings. Beginning with Emperor Nero to

Produce a written technical report on one of these topics (please see Essay

Produce a written technical report on one of these topics (please see description) - Essay Example Turbine gas engines have almost replaced the piston engines in the aviation industry for aircraft power generation. Categorized as turbojet, turbofan, turboprop, or turboshaft engine, the gas turbine engines are the most significant breakthrough in the history of aviation. Constant (1980) highlights that specific to their purpose, different types of engines are employed in the industry. Design characteristics including number of spools, principle of compression, distribution of airflow within the engine, utilization of the exhaust gas are the main deciding factors for this purpose. Basically, four types of turbine engines are used in aviation industry, these include In Turbojet and turbofan engines, reaction of exhaust gases leaving the exhaust nozzle is used ro produce thrust. Turbofan engines are further classified as as high-bypass or low-bypass-ratio engines based on requirements of mass flow. A typical schematic diagram of turbofan and turbojet engines is shown below for reference study. In third type of gas engines, turboprop, propeller is driven a turbine rotated by hot gases. Major portion of the exhaust gases is absorbed by turbine to produce mechanical work with a very small portion to produce thrust. Below is a schematic diagram of the turboprop engine. Air intake is the most important part of a subsonic and a supersonic aircraft as it ensure optimum supply of air to engine for producing required thrust. The design of intakes depends on engine requirements and aircraft design speeds. since the primary task of air intakes is to supply air for engine, then the ultimate responsibility for air intake design is attributed to aircraft airframe designer rather than engine designer. Therefore, it is important that both designers work in coordination with each other to reach optimum design (Mattingly 2005). The intake design such that it ensures that required amount of air

The Western Experience Essay Example | Topics and Well Written Essays - 750 words

The Western Experience - Essay Example Indeed we were going to the new world that we did not know anything about although we felt that there must be wonderful things that we needed. Reaching the new land which was strategically located in the Pacific Northwest part of the country prompted us to take a journey which is popularly known as the Oregon Trail. The hardship we experienced with our children was one of its kinds. I influenced my family because I wanted to start of life in the west. In the beginning, the desire to explore new world overwhelmed me and I could not think about any other thing (Peavy & Smith, 1998). Before the adventure life was very interesting and relaxing especially to women who did not have much to do in their homes. Women did not expect their men to explore the tales of gold and prosperous green land in the west because their husbands were already established businessmen or working on their lands. I initially believed that life was satisfying because I did not lack anything I wanted (Woodworth-Ney , 2008). However, one time I just changed my mind and decided to explore the great things that existed in the west. There was severe depression in the Midwest as well as propaganda from fellow traders and other government officials regarding the fertility and the value of land in the west. I fully packed my wagon with foodstuff such as beans, coffee, dried meat, flour as well as clothing and furniture. Interestingly, I had to drop some of my heavy household items such as furniture because they were too heavy to be carried while crossing rivers (Peavy & Smith, 1998). Although we ran through fairly even country of the Great Plains, there was a good number of obstacles on the way such as the perils of crossing rivers as well as the candid risk of the Indian attackers. We drew our wagons into a circle at night to create a rough-and-ready barrier for fear of the India attacker. Few people died from accidental discharge of firearms or be drowned while we were crossing rivers. In addition, there were other more mundane causes such as diseases, some people would fall off horses and the difficulties of walking along rocky terrain that was full of steep ascents and descents as well as injuries got from overturning and runaway wagons (Woodworth-Ney, 2008). I travelled almost 2000 miles along with other pioneers whom we were forced to travel through five states after the journey began in Missouri. The journey was full of people with different ages and sex. Most of the women we travelled with complained that their husbands forced them to take the journey in search for new places despite the fact that they were already established in their homes (Woodworth-Ney, 2008). Travelling in group was amazing since we could make stories and also for our safety. Some of our properties were being robbed at gunpoint by highway people along the trail. It was really heartbreaking to see women bearing children and losing them on the way due to unbearable conditions thus forcing them to liv e the bodies behind (Morito, 2012). Jefferson wanted to boost the economy by using resources which would arise due to exploration of new fertile land. I currently stay in Williamette Valley. There were several significant technological, infrastructural and economic growths that resulted as the Oregon Trail. Domestic farming was introduced into the West because of enormous herding and introduction of the domestic animals by us. Surprisingly, I can see some of the modern highways and railroads built alongside the Oregon Trail.

No-Fault Divorce Essay Example | Topics and Well Written Essays - 1250 words

No-Fault Divorce - Essay Example In the first decade of this century the grown of divorce rates has reached almost epidemic proportions in the United States with as many as 12 million divorces registered over the 1990s which is the highest the developed world (Williams, 2000). Consequently, a number of experts view no-fault divorce as one of the key contributors to the increasingly high divorce rates in the US. Even brief analysis of the no-fault legislation and specifics of divorce granted under it suggests that such belief relies on solid evidence and might be absolutely correct: no-fault laws in their current form must be revised on the basis of sociological and legal experience that has been accumulated over the last three decades. The concept of no-fault divorce does not require demonstration of any proofs or evidences of wrong-doing to dissolve a marriage. The first state to adopt no-fault laws was California where they came in force on January 1, 1970. The example of California was soon followed by other states that implemented similar legislation. Prior to that, the procedure for obtaining a divorce involved mandatory provision of evidences demonstrating fault of one of the spouses. Requirements to the nature of such evidences were strict too. It was not sufficient to make a mere statement of not loving the spouse: only a proved case of committed adultery, wrongdoing, abandonment or other serious guilt qualified as a valid reason for divorce. At the same time, the spouse who preferred to save marriage had most instruments to do so. Therefore, it was up to the judge to weigh all evidences provided by both sides to the marriage, and often the decision regarding granting divorce was negative (Baskerville, 200 0). The sophisticated divorce procedure forced many couples who did not commit any act sufficient for the court to grant divorce seek for the way to bypass it. This resulted in numerous tricks and legal fictions invented by lawyers to satisfy the needs of such couples. For the most part, these tricks were based on false testimonies. This tendency produced highly negative response from the legal community with numerous judges and lawyers arguing against the excessively strict divorce procedure. The key concern was that such increase of perjury cases occurrence might undermine the reputation and integrity of the US system of justice. Advocates of a simplified divorce procedure claimed that adoption of no-fault laws was a better choice than forcing spouses continue living together or making perjury (Friedman, 2002). Although the no-fault legislation apparently simplified the divorce procedure, there has recently been a considerable movement for revocation of no-fault laws in the United States. Several key problems are associated with the concept of no-fault divorce. Firstly, the initial objective pursued by authors and advocates of no-fault laws was to facilitate dissolution of marriage by mutual consent of both spouses. However, it turned out that in most cases mutual consent was not in place and the new procedure enabled any party to the marriage to dissolve it without the other party's agreement. Thus, according to some estimates four out of five no-fault divorces were unilateral with only one of the spouses insisting on ending the marriage (Baskerville, 20

Communication Media Essay Example | Topics and Well Written Essays - 1500 words

Communication Media - Essay Example Another name in this category is of a female artist Noor Jehan from who has sung songs to boost up the morale of Pakistani Army at kargil war (fought between India and Pakistan).Many people believe that her songs enabled young soldiers to die for their country with such a great passion. This was the power of this specific medium that not only contains healing power but also had the power to reinforce our goals of life. Sometimes we listen to a particular song and think that this is made for us as it represent our goals of life, dreams or the way I want to live life. It won't be wrong if we say that songs have become the tool of mass media. History of human world is a strong evidence of the power of songs and one of its example is the freedom of African American or "black people" when they accepted Christianity and started composing songs to preach the particular religion. They also used songs as a medium to express their feelings after getting freedom. These songs contain lyrics like : Steal away, steal away, steal away to Jesus Steal away, steal away, home I aint got so long to stay here My lord He calls me, He call me by the thunder The trumpet sounds within my soul I aint got so long to stay here Many Africans accepted Christianity after hearing such effective lyrics. People remember the freedom of African Americans because of these songs so directly or indirectly these songs also played an important role in analyzing the history of African Americans as well. Music is no longer used for entertainment purpose only but a sort of infotainment that portrays our thoughts, ideologies, religion and needs in some cases as well. Robert Wyatt has also composed lyrics on mass media as a tool of communication which says: And as history... This report approves that songs are also used as alternative mean of communication for children who do not respond adequately to traditional treatment approaches. Physiotherapist through out the world use music or songs to do therapies and believe that it’s a way of relaxing the mind and body of human being. Not only human beings but birds also use songs as a tool of communication. This essay makes a conclusion that that music was and is used as a tool of communication and is a powerful medium of communication as well. Today the songs or lyrics that are dedicated to represent cultures, religions or ideologies will be used by historians of tomorrow to analyze the history. Many young artists of today use music as a way to reinforce the mutual goal of today’s young generation and boost up their morals to do what they should do and majority of these songs are liked by masses. Along with TV, radio, internet, publications and other forms of communication song is also a communication medium which is much older then all the mentioned forms. Researchers, historians and media people have accepted songs as a communication medium and so did many of common people. No wonder the way this medium is progressing; it could become one of the most popular medium of communication among masses sooner or later. Every culture of the world has cultural songs that represent their culture and ideologies. The purpose of composing such songs is to let the historians of coming generation know about the particular culture and indirectly a message that the particular culture doesn’t want itself to be forgotten from minds of the people.