Dilemma of International Community

The US prevention strategies against international terrorism have come a long way since the mid-1990s. The disciplined, centralized organization that conducted the September 11 is diminished because most of the group’s senior and midlevel leaders are either incarcerated or dead, while the majority of those still at large are on the run and focused at least as much on survival as on offensive operations. However, Al Qaeda still has the potential to impose lethal threat.From the critical standpoint, the key challenges for contemporary counterterrorism efforts are not as much Al Qaeda or any other terrorist organizations as what will follow them. The emerging primary terrorist threat includes the global network of mostly Sunni Islamic extremists, which extends beyond members of Al Qaeda. The foundations of these extremist sources remain very much alive and in some cases are growing deeper. Practically, they contain the interconnected economic and political systems of the Muslim w orld.In addition to â€Å"Muslim† factor, there is a widespread opposition toward U. S. policies within and toward the Muslim world, especially the U. S. political position on the Israeli-Palestinian conflict and, which is more important, the invasion and occupation of Iraq (Byman, 2003:61). Considering the mentioned trends and reasons, the counterterrorism challenges after the liquidation of Al Qaeda may very well be even more complex than they were before.Decentralization and secretive nature of terrorist plots as well as indeterminate nature of the final target imposes extreme challenges on the intelligence. While the mission of intelligence in counterterrorism is to monitor and prevent terrorist activity, practically it may become vain due to its inability to identify terrorist groups and individuals. However, even a decentralized terrorist threat has some connections that can be discovered, and this will constitute the core of intelligence counterterrorist efforts.From t he practical standpoint, although almost every extremist can be connected at least indirectly to the network of Sunni Islamic terrorists, the majority of linkages includes only casual contacts and do not involve preparations for terrorist operations directed against the United States. No intelligence service possesses the resources to monitor all of these linkages, to construct the life history of every terrorist, or to compile comprehensive sociograms of the radical Islamist scene (Rothkopf, 2005:34).International community’s willingness to assist in the struggle against terrorist organizations to the major degree has depended on Al Qaeda’s record and menacing capabilities. However, from the contemporary point of view, foreign cooperation becomes more problematic as the issue moves beyond Al Qaeda. Mentioned difficulties that the United States has already encountered in dealing with Lebanese Hizballah depict some of the problems in more generally enlisting foreign hel p against terrorist groups (Byman, 2003:63).An underlying limitation to the willingness of international community to collaborate with the United States on antiterrorist efforts is the skepticism among foreign political elite that the most powerful country in the world needs to be preoccupied with small groups of radicals. Critically, the skepticism of foreign community can be considered in terms of fact that the U. S. preoccupation is no longer with the group that carried out the terrorist attacks on September 11 (Nash, 2004:56). However, the most significant challenge to the U. S.counterterrorist efforts that may emerge along with a more decentralized terrorist threat is the ability to uphold the nation’s own commitment to struggle it. Surprisingly, the American society has revealed that its determination to fight counterterrorism can be just as inconstant as that of foreign publics. During the past quarter century, the U. S. public and government has given different and co ntradictive attention, priority, and resources to U. S. counterterrorist programs, with interest and efforts increasing in the aftermath of a major terrorist incident and declining as time passes without an attack.International Threats of Terrorism From the critical standpoint, it is clear that even being the world’s only superpower the United States can no longer sustain a war on terrorism. Due to inability of the US to provide detection, monitoring and elimination of 100 percent of international terrorist groups, international cooperation in this area seems to be a promising solution. Moreover, terrorist organizations are now acting across the domestic borders of hosting states, jeopardizing security of entire international community and recent terrorist acts in London’s subway became an evident support for this statement.Brian Jenkins underlines that the success of terrorism has much to do with the perception of a nation’s capability to deal with such crises, proposing that â€Å"public perceptions of government standing and competence in combatting terrorism are based not on overall performance, but rather on performance in a few dramatic hostage incidents, where the government, of course, suffers disadvantages from the outset† ((Jenkins, 1983:10). Indeed, the public sees the government only in crisis, demonstrably unable to provide security for its citizens, sometimes yielding to terrorists to save lives, unable to bring its enemies to justice.Practically, a rescue attempt or successful prevention of an attack adds immeasurably to a nation’s image of military prowess, while an attempt that fails does incalculable damage. Many statistics exist to quantify the activities, numbers, types, locations and targets of international terrorists. It was reported in 1986 that â€Å"incidents of terrorism – those involving citizens or territory of more than one country – have doubled in number since 1975, to slightly o ver 800 last year [1985]† (Hanley, 1986:3).Notwithstanding the bombings in August 1998 in Kenya and Tanzania, there are analysts who believe terrorism has been in decline in recent years. â€Å"Patterns of Global Terrorism: 1997†, published by the American State Department, reported that there were a total of 304 acts of international terrorism, one of the lowest annual totals since 1971 (US Department of State, 1997). According to Patterns of Global Terrorism: 1998, the number of acts of international terrorism dropped to 273 attacks. However, in 1998 there was a record high toll of 741 people killed and 5,952 injured in terrorist attacks (US Department of State, 1998).In 2000, there were 423 terrorist acts, an increase of eight percent from the 392 attacks in 1999. The death toll for 2000 was 405, and 791 were wounded (US Department of State, 1999, 2000). The year 2001 witnessed a dramatic increase due to the audacious attacks on 11 September of that year. Many commen tators agree that terrorist violence is, and will likely remain, an integral part of international relations. As Scotland Yard’s counterterrorist specialist George Churchill-Coleman stated, â€Å"Terrorism is with us now, whether you like it or not. You’ve got to adjust your way of life to that† (Hanley, 1986:3).This mentality has now reached the American scene as the head of the Office of Homeland Security, Tom Ridge, noted, â€Å"We need to accept that the possibility of terrorism is a permanent condition for the foreseeable future. † He stated, â€Å"We just have to accept it† (Calabresi & Ratnesar, 21). At airports there is a â€Å"get on with the job† attitude and in daily living one must accept the need to be on guard, like steering clear of suspicious packages and reporting them to the local police. One columnist wrote, â€Å"By not surrounding the (terrorist) incident with hysterical posturing, we cut it down to size.We make it seem a nuisance rather than a cataclysm. We stifle its capacity to instill terror. We decline to be afraid† (McCabe, 1996a:4). In that regard, Great Britain is one of the few nations which is intimately familiar with terrorism and its impact. Lacking any other alternative, the British have essentially learned to live with the threats and the bombings. Moreover, the British have learned to live with intrusive surveillance cameras, the cost of bomb insurance (3. 2 billion dollars a year), as well as a higher awareness of the threat that has been assimilated into the society over the years, particularly since the late 1960s.Even despite the recent terrorist attacks in London’s subway, â€Å"the British approach to terrorism, developed over many years, seems natural in a culture that places great store on a ‘stiff upper lip’† (McCabe, 1996b:8). The prognosis becomes ever more frightening as terrorists seek out softer targets, as witnessed in the 1998 bombing s of the American embassies in Kenya and Tanzania. This is because international police and security agencies will, for the most part, strengthen the defenses of consulates, embassies and residences, and will provide other forms of personal security for the more likely terrorist targets.Therefore, terrorist attacks will probably become more indiscriminate. The bombing campaigns in Paris during the summers of 1986 and 1995, aimed at government buildings, restaurants and cafes, the bombings in London during the spring of 1992 of commuter train stations and the financial district, and the use of sarin in the subway in Japan by the Aum Shinrikyo in 1995, and the February 2001 reported discovery by the British police of a terrorist plot to release sarin into the London underground system as well as the suicide hijacking of four airliners in September 2001 are examples of what we may expect.(Other examples of indiscriminate terrorism are the strikes at airports such as those in December 1 985, in Rome and Vienna. ) Furthermore, targets abound in highly developed industrialized societies and analysts anticipate that terrorist groups will begin targeting vital points such as â€Å"computer systems, power grids and other key links of industrial societies† (Hanley, 1986b:2). Reports underline that terrorists are expanding their interests in nuclear, chemical, and biological weapons as well as information warfare.Some of these concerns were highlighted in December 1999 when the Solicitor General of Canada, Lawrence MacAulay, told the House of Commons that Canada needed to strengthen the government’s capacity to address the threat of a nuclear, biological or chemical attack by terrorists. Although the possibility of such an attack happening was low, Mr. MacAulay felt all levels of government must be prepared to deal with such eventualities (Evenson, 2001:2).His concerns followed warnings by scientists of the Health Protection Branch that a release of the dead ly anthrax bacteria in a major Canadian population center could kill upwards of 35,000 and cost 6. 5 billion to the health care system, underlining the fact that medical facilities were not prepared to deal with such an incident (Evenson, 2001:2). In the fall of 2001, a series of letters containing the anthrax virus were mailed to media centers in New York City.The letters were sent to ABC, NBC and CBS, and were orchestrated to attain the maximum amount of media coverage, while concomitantly stirring up popular fear and anxiety about these and other possible attacks. Another issue that relates to this is that of nuclear scientists who represent a valuable resource to those nations developing nuclear programs, such as modern Iran. Potential Responses to Terrorism: International Scope The evolution and deployment in the 1970s of elite counterterrorist teams in Israel and West Germany was in response, partly, to the frustrations of employing a series of so-called â€Å"non-force† methods against terrorists.Livingstone has argued that â€Å"governments have employed a variety of nonforce strategies in their efforts to resist terrorism, including diplomacy, negotiation, concessions, and cooptation. Occasionally such methods have worked, but more often than not they have failed or only provided a temporary prophylaxis to an endemic problem† (Livingstone, 1982:176). Now it is widely recognized that, under most circumstances, making concessions to terrorists only invites further acts of terrorism. This fact, combined with the failure of the U. N.to take concerted action to develop effective remedies to the problem of international terrorism, has resulted in a growing tendency on the part of national governments to resort to unilateral military action against terrorism in the belief that, if it is not possible to make terrorists answerable to the law, then they must be answerable to the gun. It is apparent from recent twentieth-century history in Western countries that the responsibility for combating terrorism has been, for the most part, that of law enforcement authorities.On occasion, army units were tasked and, for the most part, were found to be operationally wanting in a number of areas such as strategy, methodology and structure. Conventional military forces and tactics have not met the challenge of terrorism: â€Å"Not only are contemporary weapons and tactics far too destructive to be employed in heavily populated urban regions, but also the deployment of large numbers of soldiers against terrorists simply increases the number of targets at which they can strike† (Livingstone, 1982:176).General George Grivas, the famous Cypriot terrorist leader, noted that the level of terrorist operations is much lower than that of conventional military operations. Counterterrorist operations demand specially adapted and trained soldiers, tactics and strategy. He noted the â€Å"only hope of finding us was to play cat and mouse: to use tiny, expertly trained groups, who could work with cunning and patience and strike rapidly when we least expected† (Taber, 1977:118).In short, one must use those same weapons and tactics belonging to the terrorists’ inventory – psychology, stealth, speed, surprise and cunning – against the terrorists themselves. Moreover, candidates for such units must have motivation and determination, physical and mental stamina, initiative and self-discipline, be capable of operating in small groups during long-term isolated operations, and they must have the aptitude to assimilate a wide range of skills and think laterally. This type of military operation demands a different type of soldier, namely one who can develop a broad spectrum of skills.Practically, contemporary counterterrorism demands highly trained and motivated commandos, operating in small groups; skilled in electronics, communications, demolitions, marksmanship, deception, silent killing; and familia r with terrorist tactics and behavior. References Byman, Daniel (2003). Should Hizballah Be Next? Foreign Affairs 82, no. 6, November/December: 54-66. Calabresi, Massimo, & Romesh Ratnesar (2002). â€Å"Can We Stop the Next Attack? † Time, 11 March, 16–26 Evenson, Brad (2001). â€Å"Canada Poorly Prepared for Germ Warfare. † National Post, 1 FebruaryHanley, Charles (1986a). â€Å"Experts Note Common Traits in Terrorists. † Ottawa Citizen, 19 April Hanley, Charles (1986b). â€Å"International Terrorism: Global Order Shaken by Wanton War. † Ottawa Citizen, 19 April Jenkins, Brian Michael (1983). New Modes of Conflict. Santa Monica, California: Rand Corporation, June. Livingstone, Neil C (1982). The War against Terrorism. Lexington, Massachusetts: Lexington Books McCabe, Aileen (1996). â€Å"Britain Learns to Live with Terrorism after Decades of Blasts. † Ottawa Citizen, 4 August McCabe, Aileen (1996).â€Å"Facing Terror with a Stiff Upper Lip . † Montreal Gazette, 3 August Nash, James L (2004). Prevention or cure. Organisation for Economic Cooperation and Development. The OECD Observer. Paris: May:56 Rothkopf, David (2005). Can Technology Fix U. S. Intelligence. Technology Review. Cambridge: Feb. 108(2) Taber, Robert (1977). The War of the Flea: Guerrilla Warfare Theory and Practice. St. Albans, Frogmore, Herts, Great Britain: Paladin United States, Department of State, Patterns of Global Terrorism: 1997 Retrieved From < http://www. mipt.org/Patterns-of-Global-Terrorism. asp> Accessed Jan 3, 2006 United States, Department of State, Patterns of Global Terrorism: 1997 Retrieved From < http://www. mipt. org/Patterns-of-Global-Terrorism. asp> Accessed Jan 3, 2006 United States, Department of State, Patterns of Global Terrorism: 1999 Retrieved From < http://www. mipt. org/Patterns-of-Global-Terrorism. asp> Accessed Jan 3, 2006 United States, Department of State, Patterns of Global Terrorism: 2000 Retrieved From < http:/ /www. mipt. org/Patterns-of-Global-Terrorism. asp> Accessed Jan 3, 2006

Miles and Flora in ‘The Turn of the Screw’ Essay

The children in the novella are very distinctive in a manner of how the reader can perceive them. They can be seen by many as good children or bad children. In Victorian times the majority of children were actually brought up in the lower class and the middle class, Miles and Flora were not, they were lucky enough to be in the upper class but they had to follow the ideals of their mother or father. They didn’t have a mother or father therefore the governess was the only option of a friend to have and confide in, this was seen as morally wrong in the society since many Victorians believed that their shouldn’t be friendships between different classes, they believed in a strict social hierarchy. The children can be seen as innocent in the novella by the governess’ first views of them. On her first sighting of Miles, the governess describes him as being ‘angelic’, this can be seen as quite confusing to the reader since she has only just met him, it is a very powerful word to use on first impressions. But mainly it has religious connotations, it conveys a very strong image of Miles being this perfect little child, and sets him up as an innocent character throughout the entire novella. Also the governess is ‘carried away’ by Miles as well as the Master; this suggests that the governess is always in awe of strangers making her seem very vulnerable. Miles is constantly referred to as ‘little’ by the governess throughout the novella. She calls him a ‘little fairy prince’ which shows how highly she speaks of Miles, this suggests how little he is in physical appearance but mainly the innocence of him, small things are usually very vulnerable and innocent and need comfort and support from somebody bigger than them. The use of ‘prince’ not only shows how pristine he is but also correlates with his Victorian upper class position in society. This perception of Miles stays the same even until the end when his ‘little heart, dispossessed had stopped’. Since there has been many sides to Miles in the novella, the end sentence conveys how innocent he really he is. He is only a little boy and that’s what the reader needs to remember. Flora is also spoken very highly of by the governess. Generally there is more of a loveable connection between the two because they are female, and the daughter looks up to both of her parents as role models but to the mother most of all. The governess thinks that Flora is ‘the most beautiful child she has ever seen’; this is kind of inferred in the quotation but also has a very loveable element to it and an innocence one too. The governess doesn’t really experience any problems with Flora in the novella; she wants to protect her all the time from the ghosts that she believes are terrorizing her. Flora’s position in society as being upper class is also linked to by the use of her ‘hair of gold’, ‘gold’ symbolizing money but also makes her stand out in the crowd, the author has made her out to be like a little prodigy. Another perception of the children’s innocence comes with the idea if there are actually ghosts corrupting them, which the governess thinks is happening. The fact that they are only children conveys the general idea that children tend to be scared of ghosts and don’t want to hear anything about them. The children may be getting scared by the governess’ dramatic reactions to her so called sightings of Quint and Jessel. When Flora is awake in the middle of the night looking out the window, the governess, straight away, believes that she is contacting ghosts and so her suspicions about ghosts are increased but they are only children and it turns out they were only having a joke. Children can still have fun even though they are of noble birth but the governess doesn’t seem to realize this. Maria Edgeworth commented on the grave dangers of leaving young children in the supervision of servants, in this case the governess is actually a servant in social hierarchy terms but the master in terms of profession terms. The children however can be seen as being ‘bad’. The quote in the title itself tells how Miles could be being sinister. When the governess wakes up to see why Flora is standing up at the window, she immediately believes that she is contacting either Quint or Jessel because she is extremely paranoid. But when she sees Miles on the grounds of Bly she panics because not only is he all alone without anyone supervising him, he is also looking above the window Flora is looking out so the governess believes he is contacting Quint. When talking to Mrs.Grose about what happened the previous night, she watches Miles and Flora walking the grounds and believes that ‘they’re talking horrors!’, this could have several implications, one could be that they are plotting and scheming against the governess to maybe overthrow her position and get their uncle back to them and another could be that they are talking to the horrors and in this case the horrors could be Quint and Jessel since the word horror is often associated with ghosts and the supernatural. One thing that could suggest that the children are deceiving the governess and manipulating her is the fact that the employer who is the children’s uncle is nowhere to be seen at Bly. Since being employed the governess is told strictly not to contact him about anything whatsoever, not even about his own nephew and niece. This surely arouses suspicion and could possibly make the reader think that maybe the children are actually bad. Perhaps the past between Miles and Quint had made the Master resort to madness like the governess possibly has as well. It could in fact possibly be that Quint corrupted Miles before the governess was at Bly which leads to the reason why he was expelled from his school which the governess believes is a massive concern. Are the children the cause of their uncle’s behavior? And maybe, what have they done to make him not want to stay at Bly? The governess has all these sorts of questions but knows that they she cannot contact him for the sake of her job, which drives her mad because she thinks she is being corrupted. The descriptions of the children actually change as the reader progresses through the novella. On first impressions the children are compared to being like angels and royalty which is all well and good but she has yet to meet their true personalities. She describes Flora as an ‘old, old woman’ which is honestly the most ridiculous thing that a child can be called. This obviously cannot be a description of her physical appearance since she is only 8 years old but possibly how the governess believes that she is corrupted by Miss Jessel. Perhaps every time Jessel is around, Flora’s soul seems to be aging or it could actually be that she is becoming smarter with every appearance of Jessel so she is scheming more. This could suggest a loss of innocence in Flora, she used to be ‘the most beautiful child’ and now she is an ‘old, old woman’. To conclude I believe that the children are actually innocent. They are only children so how in any way can they actually be sinister and possibly evil? Yes there is strong evidence that the children could be being bad and corrupting the governess but being evil is too much of an extent. Therefore I believe in the innocence of the children.

Gender in West Africa

In the West African community, the concept of power among women lies within the vibrant differences between the roles of each gender. Women were and still are the foundation of the African community as they exercise the power to protect life and educate children. Despite this prominent position, they are not in any way seen as equal to men.This conventional perception changed temporarily, or perhaps was slightly regarded differently, when in 19th Century, Behanzin, one of the most renowned kings of Dahomey, a country now known as Benin, used his army of women to fight the French army because of the invasion of the French settlers in the Dahomey territory, which brought resistance. These women, called â€Å"Amazons,† fought with exceptional courage and were often considered invincible by their opponents.With the use of Amazons in the kingdom of Benin, a significant alteration in the gender roles occurred in the African community. This alteration, giving female soldier’s roles almost exclusively reserved for males, reflects what Butler and Kimmel discuss in their books—gender as social construct and performativity. It could be conceded that gender lines were crossed with this new position of women, but a closer look at the situation will prove the opposite to be.At first glance the physical and mental transformations of Amazons into men would make it seem that the women were able to achieve power that had been formerly reserved for men; however, on closer inspection, there is significant evidence that many features of the traditional gender norms were unchanged in the long-run, despite appearances to the contrary.

Retail business Dissertation Example | Topics and Well Written Essays - 2500 words

Retail business - Dissertation Example Secondary research involves using collecting information on a phenomenon under study from existing resources of databases. Secondary research is cheaper relative to primary research. In addition, it takes less time to collect and analyze data in secondary research compared to primary research. Secondary data analysis enables a research to analyze data from large samples. This kind of analyses would be difficult when conducting a primary research due to time and financial constraints (David & Sutton 2004, p.69; Hulley 2007, p. 207). Researchers sometimes utilize primary and secondary research methods in the same study. The information collected from secondary sources in some cases is sufficient to answer all the research questions in a study. This is particularly true for studies that many researchers have analyzed the research topic extensively and the researcher may not add any new insights into the field by conducting a primary research. In addition, sometimes secondary data is the only source of information on a research topic especially when a researcher is not able to conduct a primary research. Secondary data is useful in a research for providing a foundation or background information on the research problem. In this case, secondary data shapes the expectations of a researcher and provides the current level of knowledge on the topic under study (Wrenn, Stevens & Loudon 2006, p. 71; Webb 2002, p. 32). In the proposed study, the information from secondary sources will be sufficient to answer all the research questions. Extensive research has been conducted by independent researchers and those working under government agencies on UK’s retail sector. It is possible for the researcher to conduct a primary research on the UK’s retail sector. However, such a research would be tedious because the retail sector is large. For the researcher to obtain a sample that would be a true representation of the entire retail sector, different organizations in d ifferent industries would be involved in the study. A large sample would be required and this is costly in terms of time spent in collecting and analyzing data from a large sample as well as resource requirement. Researchers use secondary data as a source of exploratory information on their research topics. This exploratory information helps a research in designing research instruments for a primary research. For instance, a researcher may use the exploratory information as a guide to formulating questions in a questionnaire or for focus groups. The nature of existing secondary data on a research topic can help a researcher in making a decision on the most appropriate research design to use in his or her studies. For instance, secondary data may indicate past attempts by other researchers to conduct primary research on a topic and their success or failure. If past researchers have ruled out the possibility of conducting a primary research in a certain filed, secondary data will help a researcher to save time and resources by adopting a secondary research design (Wrenn, Stevens & Loudon 2006, p. 72). The existing literature on UK’s retail sector indicates the significance of the sector to the economy as well as its magnitude. The retail sector is large and consists of very many significant industries. Past researches and government publications indicate its trend over the years including its performance during the financial crisis. This

Summary Essay Example | Topics and Well Written Essays - 1250 words - 3

Summary - Essay Example Hedge fund is often depend on the manager’s expertise, is largely offered as private investment, is structured as limited partnership and often presents a narrow range of investors. Compared to the traditional funds, Hedge funds; have an industry size of $2.6 trillion, it has an absolute return, it has short or long investment, has high strategic complexity, has lower correlation to the market, has leverage, higher turnover, high based on performance, has large minimum investment and a low transparency. Investors are high net worth people, institutional investors and funds of funds managers. For hedge funds, the minimum size of investment is often high and at least 1 million dollars. Investors often seek stable, attractive and non market correlated returns. Pension funds make up 15%, followed by individual funds 30%, endowment 12% percent and corporation 11% (Zimmermann, 2009). Hedge fund strategies cover aids in representing the hedge fund universe that includes event driven, long/short equity, global macro, multi-strategy, emerging markets, fixed income arbitrage, managed future. Event driven strategy helps to exploit pricing that results from corporate events that are often anticipated. Managed futures strategy is also known as commodity trading advisors and is an approach aimed at investing in futures contracts in equity, bond, current market and commodity (Zimmermann, 2009). It utilizes pattern and trend recognition models as well as means reversion. Fund of hedge funds entails investing in another hedge fund. The main aim is the fund, manager and strategy. Some of the key risks to the hedge fund strategy entail poor liquidity, high leverage, lack of regulation, operational risks and lack of transparency (Zimmermann, 2009). CPP is the proportion portfolio insurance which aids in ensuring a hundred percent of the capitals of the investors is protected. CPPI determines the composition of investment

The Theory of Corporate Finance Assignment Example | Topics and Well Written Essays - 3500 words

The Theory of Corporate Finance - Assignment Example The company's pricing data revealed that the Staples planned to establish their monopoly, and wanted to increase the prices of their product 13% after the merger. The merger was therefore criticized and blocked by the trading regulatory organizations, this saved 'consumers an estimated $1.1 billion over five years' (Yang, 2005), which otherwise would have been spent towards high prices. The acquisition and merger of the supplier with the reseller are regarded as a vertical merger. In the case of the vertical merger, both the parties are involved in the buyer-seller relationship. The acquisition of the Medico Container Services by Merck is regarded as a vertical merger. The regulatory authorities have appreciated exercises of vertical mergers. It is expected that consumers are also able to benefit from the vertical mergers, because such activities i.e. the integration of the supply chain, increase the efficiencies, the prices stabilize and quality of the services also improve. The mer ger of the Time Warner Inc. and Turner Corp., which are entirely different entertainment networks, has improved the services of the entertainment giants greatly. The regulatory authorities expressed their concerns that Time Warner after merger will be reluctant to offer and sell its video programs to other competitors of the cable TV companies, and Turner Corp. will have extra benefit through such bargains of merger, and Turner Corp. will be offered to programme right at discriminatory rates, therefore both the companies will establish their monopolies against other competitors including Direct Broadcast Satellite and new wireless cable technologies. The regulatory authority also feared that the merger will affect competition in the production of video programming; the merger will allow Time-Turner to refuse the services of transmission by competitors. The regulatory authority, therefore, approved the merger as it was likely to improve the services, but ' Direct Broadcast Satellite and new wireless cable technologies' (Yang, 2005). The Corporate Diversification has been discussed in detail by the financial economists, the analysts are of the opinion that corporate diversification has a lesser degree of favorable impact in judging the benefits of diversification for different reasons. The primary reason is that 'any diversification possibilities that corporations might have, will, in a perfect capital market, already have been exhausted through shareholders' individual portfolio choices' (Yang, 2005). The secondary reason is that the diversification discount i.e. the diversified corporations have the privilege to trade at discounted rates as compared to their non-diversified counterparts. It has been therefore concluded that corporate diversification is neutral, but has the potential to damage strategy. Surprisingly, the corporate diversification has been strong practice, 'At face value, diversification can be explained by the fact that when pooling income stre ams that are less than perfectly positively correlated, the resulting income stream is less volatile than were the constituent income streams' (Yang, 2005). The dilution of the risk factor, therefore, has the potential to be beneficial. The critics of the corporate diversification are of the opinion that any reduction that can be achieved through diversification, by any of the firms, 'can be replicated by the individual shareholders through an appropriately chosen portfolio'.

It 1 Essay Example | Topics and Well Written Essays - 500 words

It 1 - Essay Example Furthermore, experts in the IT sector require prior knowledge in business strategies and the technological sector. Therefore, IT management is about management because in all business entities, management usually involves togetherness to accomplish certain objectives using available resources. I think that IT experts have a clear understanding of the business better than other individuals in the business sector. In fact, IT experts have the ability to gain a better understanding of the business. It is quite clear that there is no other department in the business sector which interacts with diverse parties as compared to the IT sector. In fact, in the contemporary world, most activities usually require IT information and skills. This has been significantly attributed to the development in technology. Research asserts that business knowledge and technical knowledge should be merged together to improve the overall functioning of the company. If the business experts and the technological individuals share knowledge, communication can be enhanced significantly in the company. This affirms that the overall performance of a company can be improved by the business manager and the IT experts (Austin, Nolan, and O’Donnell 11). According to Barton, it is quite evident that business knowledge and technical knowledge should be merged together. According to the context, the capability gap is depicted by two hills and a valley between them. One of the hills represents the executive side while the other side represents IT leaders. The executives are supposed to acquire enough understanding of a business to become effective IT experts. This capability gap is brought about by the fact that business executives lack knowledge in IT management. Lack of communication between the business executives and the IT department has also contributed to the capability gap. Barton explains that it is difficult to bridge the

Zachman Enterprise Architecture Framework Analysis Assignment

Zachman Enterprise Architecture Framework Analysis - Assignment Example It should be noted that the framework is not an ordinary model but more of a conceptual model, a composition of concepts, in that it exists in its applicability, mental synchronization and or personal/mind interpretations so as to guide the user to know, understand and where possible simulate the ideas in a practical situation (Raynard, 2000). Enterprise framework differs with structural/building framework in that as the building framework seeks to apply the laid out methodology, that is, to collect, manage and use information to achieve a prescribed/ designed model(s) to a tangible object, enterprise framework seeks to transform the abstract ideas, that is, intentions and semantics through designing documents, specifications, considerations of available models; without implying any specific and /or defined process. Therefore it can be viewed as a process to think, apply, re-apply, evaluate and solve problems through formalization and effective communication (Zachman & Geiger, 1997). With this in mind, we shall look at how Zachman’s enterprise architectural framework applies in reality by first understanding the types and scope of its architectural design. Types and Scope For conceptual enterprise architecture to be effective, there should explicitly define techniques to help individuals understand the represented system, it should convey the system details to the stakeholders, should provide a point of reference so as to simplify extractions of system specifications by designers and it should automatically and/or in a simplified manner, document the system for future reference and provide room for collaborations and implementation (Fishman & Selkow, 2003). For instance, it should first analyse the need for transformation within a given organizational process/intention or a phenomenon cross examine the available concepts to come up with a conceptual model and ideas to achieve the transformation. It should analyse the validation of the process, clearly sh ow its specifications analysis and the simulation process. It should reflect accreditation, verifications of the perceived implementation and execution and finally outline the expected results and the impact (Uckelmann, 2012). The Zachman’s enterprise architecture is based on six core questions; what, how, where, who, when and why, which form basis of applications in the modern organization. To come up with stronger arguments and justifications to support the model, these questions are further analysed in different business perspectives such as the scope: which seeks to explain the contextual business activities, the business model: which is the evaluation of the conceptual nature of the organization and its stakeholders, the system model: which is the logical approach of the required transformation in line with the business needs, technology model: it represents the physical and the intended aspects by the transformers of the new phenomenon, detailed representations by other members of the transformation and finally the analysis of the functioning enterprise. The Scope/ Contextual Approach The planner tries to figure out: what content will the framework contain and/or the overall model represent? This call to ascertain and prioritize on all important business processes and what transformations can bring an impact. This may take course through the analysis of available data and the projected/intended goal. The planner then needs to ask how the conceptual model will be presented. This seeks to explain the functioning of the perceived model which can be achieved through intensive analysis of the core

Photography Research Paper Example | Topics and Well Written Essays - 4000 words

Photography - Research Paper Example Part 3 Digital photography has changed the way we see the world around us. It has opened up the world of photography to anyone with the ability to peer through a viewfinder and push a button. It has made it possible for us to easily pull images into our computers and change the captured reality. For this reason, it has become a concern that digital photography has changed the face of photography forever. We can no longer look at an image and assume that it is depicting what really happened at the time the photograph was taken. Many people remain suspicious about digital photography because of the ease with which photos can be manipulated, but this aspect of photography hasn't really changed since its earliest days. Part 3 Digital photography has changed the way we see the world around us. It has opened up the world of photography to anyone with the ability to peer through a viewfinder and push a button. It has made it possible for us to easily pull images into our computers and chang e the captured reality. For this reason, it has become a concern that digital photography has changed the face of photography forever. We can no longer look at an image and assume that it is depicting what really happened at the time the photograph was taken. Many people remain suspicious about digital photography because of the ease with which photos can be manipulated, but this aspect of photography hasn't really changed since its earliest days. By looking at the history of photography and how it has been affected by digital technology, I plan to show that manipulation of photos is something that has been a part of photography for as long as cameras existed. To do this, I will show how the function of the digital camera is not really that different from the function of the traditional film camera and then show how each method is easily manipulated to create an impression of reality. The only true difference is our realization that this is possible. Digital Technology Has Not Chang ed Photography Student name Course name Instructor name Date Student name Instructor name Course name Date Digital Technology Has Not Changed Photography The world as we see it today is mostly shaped by what is captured in the form of digital photography. Film cameras are almost non-existent as more and more people have found the ease and cost-convenience of digital to far outweigh the hassles of film for most applications. Because of its widespread use, we are all now much more aware of just how easy it is to manipulate photographs to change what we think we see. While most of us embrace the ease of digital photography for ourselves, there is a group of individuals who are outraged at the idea that news photographers are also able to use digital technologies in reporting the news. These people feel that the only way we can get an accurate representation of what's happening in other parts of the world is through the use of film cameras, which produce images that are not as easy to m anipulate. My role in the following research is to investigate how film cameras and digital cameras operate to see if there are any differences in the actual capturing of an image and then to compare how images are processed, again with the purpose of comparing techniques and the level to which they can be manipulated. In conducting this research, I bring my own experience as a film and digital amateur photographer as well as someone interested in how the media works to shape our understanding of the world. I have studied how images are used in print ads, video

Korean Christianity Paper Essay Example | Topics and Well Written Essays - 1000 words

Korean Christianity Paper - Essay Example However, the strength of the influence in the clergy, which was once a driving factor in moving the people, now lay down at the side, and materialism as well as influences from other cultures has taken over. Prior to being divided into the south and the north, Korea was once a single nation, being ruled by s single government. Around the 1880’s foreign missionaries started to enter the nation, but was not readily accepted by the people due to various conflicts in their teachings as well as the already present traditions in Korea (Lee 117). Moreover, only some of the educated elite which had the chance to study in Japanese or American universities were successfully converted to Christianity. Common folk, called minjung were still worshipping their ancestors and offering them food and wine, among others, which has been the norm for more than a thousand years (Oak 1). Thus the conversion of Koreans during the start of the 20th century was rather slow and limited. The conversion f rom the pagan religions of the masses and the Confucian and Buddhist principles in the upper class society of Korea was not an easy task. Foreign missionaries did not have an idea that deeply-rooted religions associated with ties to families and ancestors would be hard to break, and converts would have to face ostracism from their families or suffer severe torture or death (Oak 5). Many Koreans also see the conversion as a strong political force that yearns to topple the government, thus many oppose to being converted. Most of the elite that were sent to Japan, the United States or any other country either as a diplomat, a scholar, or exiled were easily converted to Christianity, but their ideals were not easily accepted by many, and people would rather cling to old traditions than lose their families in the process (6). However, after the great depression of the 1920’s and the continuing struggle for independence after being annexed by Japan, Protestant Christianity was prom ulgated by many of the movement’s leaders and revolutions regarding the economic and political reform ensued (118). The association of Korean pride, self-sufficiency and nationalism was spearheaded by a Presbyterian Elder named Cho Man-sik, which was a man with a lot of experience regarding teachings in Christianity, governing a school, and law (Wells 828). In order to initiate the economic stability of Korea (which was struggling due to low wages as well as dependence on Imperial Japan), Cho lived in simple house and worn traditional clothing suited for heavy work, among others. Becoming the symbol for New Korea, Cho held seminars and rallies to push the rest of the nation to become self-governing and self-sufficient (829). Making the people move was something that the socialists were not able to do alone. Protestant Christianity as a religion took its own course and development as well as the integration into the lives of the common folk through the subtle intermingling wit h pagan traditions. Initially, Korean Protestantism was not iconoclastic and sacral in nature, but due to the strong ties of shamanism and other pagan religions, it eventually evolved as such. Also, since the presence of sacred artifacts, people and places was already being practiced, these influenced how converted people worshipped in their faith (Lee 8). And since the lower classes, or minjung were easily converted into Christianity due to the adaptation of old customs, there was an explosion of

Rail car brake caliper Assignment Example | Topics and Well Written Essays - 500 words

Rail car brake caliper - Assignment Example Non-Ferrous metals are costly. Yield strength refers to the minimum tension that yields plastic deformations (Somaiya, Wieffering & Blaine, 2008). Tensile strength refers to minimum stress essential for the failure of the material. Fracture resistance is significant in measuring strain degree. Describes the resistance of a material to fracture and is measured using the aggregate energy contained in the material (Somaiya, Wieffering & Blaine, 2008). In the design of the brake caliper, toughness is important since strong materials absorb more energy compared to fragile ones. Tension tests include; static tension tests, which define the infringement point of the material and compression tests that determine the material’s reaction to crushing (Somaiya, Wieffering & Blaine, 2008). In general, tensile testing determines the strength and amount of stretch in the material. The failure point is the ultimate strength. Torsion test measures the relationship between stress-strain of a material. Hardness tests, which include Brinell hardness test, which uses a steel ball with enormous force. The applied weight for harder materials like iron and steel is about 3000kg while that of softer materials like aluminium alloys and copper is about 500kg (Somaiya, Wieffering & Blaine, 2008).Vickers hardness test is obtained by dividing force by the external area. Rockwell hardness test measures the penetration depth in the material to determine the hardness. Scratch test involves scratching harder materials to rank their hardness. Harder materials scratch the softer ones. Mohs hardness scale is applicable. Rebound test utilizes changes in potential energy to determine the hardness. Indentation tests utilize the impression of force on the material to test for hardness. Aluminum oxides make calipers abrasives that boost friction because of its low density. Steel filler recommended

Patterns and trends in health and illness Essay Example for Free

Patterns and trends in health and illness Essay Women are more likely to become ill than men for many reasons. Men are likely to have strong immune systems than women as they tend to put themselves first, whereas a woman has different priorities. Another reason why women may become ill opposed to men is the fact that a lot more women have to work the double day than men. The double day consist of the individual going out to work on a day to day basis and then returning home to start chores. These chores can be anything from looking after the children to cleaning the house. A person who works the double day are more likely to become ill as they are more likely to become stressed or exhausted, both of which can lead to the individual becoming ill at a later stage. Men are seen to have more physical or dangerous jobs than women, which should mean they become ill on a more regular basis. However this is not the case because a lot of men return home from work and then relax, whereas the women go to work and then come home to situations such as sorting the children making sure all the washing and things are complete. This is not always the case as it could be the male that has to work the double day but it is usually the women. On the other hand women take better care of themselves, which is shown by the fact that women seem to live longer. Elderly and Youth Elderly people are more likely to become ill than a young person as things such as their immune system are no longer as strong. This means that it takes and elderly person longer to recover from an injury or illness than someone who is a lot younger than them. If an elderly person’s immune system is weaker it means that they are likely to catch the illnesses quicker and they could catch more than one illness a time. The youth of today are also a lot less likely to break a bone than the elderly, as the elderly’s bones are a lot weaker than those of a youth. If a youth is ill they usually recover by themselves and only occasionally rely on the help of medication, usually when the illness is strong or aggressive. Whereas an elderly person can take weeks to recover and often rely on medication for support. Rich and Poor Poor people are more likely to become ill than richer people as their life style is not to the same standard. The poor are more likely to live in cold conditions and have a poor diet whereas the rich are more likely to have good healthy diets and live in homes with central heating and that are clean. Rich people are also at an advantage when it comes to being ill as they can afford treatment and medication. This means that they are likely to recover quicker and don’t have to worry about still being able to pay for other necessities such as food and water. The poor however have other priorities to spend their money on such as providing a shelter for their children, food and clothes. This means that medication is one of the things that is given less thought. They would rather the child be fed than them paying for medication for themselves. On the other hand poor people are likely to smoke and drink than those who have more money

Outline Of Critique Of W E B Dubois History Essay

Outline Of Critique Of W E B Dubois History Essay W.E.B. DuBois, is one of the greatest African American thinkers, oraters and writers of history. His works are often bold assassinations of the development of the Black, former slave class in the US, through periods were they repeatedly faced bold and subtle racism but were simultaneously expected to be successful, because laws were, better than they used to be. DuBois work The Souls of Black Folk, though constituent of several divergent essays is to many the source and center of nearly all his messages regarding the truth telling that needs to be done, in history to properly place the plight of Blacks into the context and even to some extent the present. According to the editor of the W.E.B. DuBois reader, which republished the whole of The Souls of Black Folks in its pages the works purpose is;to transcend the pain and liabilities of the past while remembering and restoring the power of the African American heritage- and this theme, à ¢Ã¢â€š ¬Ã‚ ¦runs throughout The Souls of Black Folk. No work before or since has met the challenge so well. (Sundquist 99) Summary As was stated in the introduction The Souls of Black Folk,consists of several thematic essays regarding the position and reality of black life through its history in the US. Each work discusses a theme of necessary report and honesty. According to DuBois himself, in his forethought to his collection he ..sought here to sketch, in vague, uncertain outline, the spiritual world in which ten thousand thousand Americans live and strive. (DuBois 100) The first two essays discuss the meaning of emancipating to blacks, and its aftermath. The third chapter deals with the relatively slow progress of personal leadership, criticizing heavily the president of the Tuskegee Institute, for capitulating to the idea that trade skills rather than intellectual development is the necessary next step in the development of blacks. In two additional chapters he juxtaposes the world of blacks in and outside what he calls the veil i.e. the black world and black men in the white world, and dealing specifically with how such a color line as it exists could realistically train black men to live productive lives. He then covers black poverty in two chapters and closes with a chapter on what he calls the, present relations of the sons of master and man. (Dubois 100) Black Spirituals as Thematic Introductions It as been pointed out by many that Dubois use of black spirituals to open the themes of his essays was masterful in several ways, in part because it sets the tone for how the theme to be discussed realistically played a part in the lives of blacks, as such spirituals were often the only form of mass communication available to black men and women during large periods of their history in the US. Additionally, he has been praised for their use because they cannot be found anywhere else, as an oral tradition, forced by the illegality and if not then the unconventional allowance of literacy among blacks. The black spiritual loses is power as those who have used it to communicate joy and woe begin to die off, as with all other oral traditions, the death of people often marks the death of tradition, if such tradition is not communicated effectively to the next generation. This loss, is substantial and in some ways DuBois purpose is to stress the deeper meanings of these spirituals by intel lectual and political discussion, that he as an educated African American can do. Most importantly an educated African American man, who unlike Washington, was willing to tell the truth, rather than capitulate to the standards of white society, in his beliefs assertions and expectations of his brethren. A foundational example, and theme that pervades the work can be seen in the spiritual he uses to introduce the theme of chapter 2, Of the Dawn of Freedom. Careless seems the great Avenger;/Historys lessons but record/One death-grapple in the darkness/Twixt old systems and the Word;/Truth forever on the scaffold,/Wrong forever on the throne; (DuBois 107) The chapter stresses the extreme juxtaposition of legal emancipation, following his first chapter which discusses the great hope that emancipation and freedom would be real, and the lack of real systems to allow for the development of black men and women that follow it. DuBois makes clear that the hope was met with constant dashing, a s the reality of the world of blacks was constantly stunted by traditions, fear and racially motivated systems that still barred blacks from success and the expression of free will. Truth Telling There is no better chapter to discuss with regard to truth telling in DuBois work that that which adamantly attacks Booker T. Washington. Washington, in the eyes of many whites (and even some blacks) had the most logical and rational response to the development of blacks in society. These men and women would need to be trained to do work, work that is demonstrative of their previous restricted options. Washington believed that the black race would be most successful if instead of fighting for the right to hold positions and vocations that had been previously reserved only for the majority, they would seek to work with their hands and train to make those works more productive. To DuBois and other intellectuals this was an assault on blacks as it continued to stress that their abilities were less than those of whites and perpetuated the idea that most blacks would not be able to hold real positions of vocational power, such as those achieved through traditional white only higher educat ion. DuBois stresses that Washingtons capitulation, offering one of the only advanced education options for blacks as a trade school, that did not stress the need to develop intellectually was paramount to supporting white society, as blacks had always done. The Tuskegee institute did not train the first round of black attorneys, doctors, professors, entrepreneurs or anything like them it continued to train blacks to provide services to whites, only to do it more scientifically and better. Not only that but Washington came to a position of influence precisely at time when it might have been possible to begin to offer blacks better options than trade training and yet he chose to capitulate, and as the only scale offering of any advanced education to blacks his school succeeded and his ideology of a, à ¢Ã¢â€š ¬Ã‚ ¦programme of industrial education, conciliation of the South, and submission and silence as to civil and political rights, was supported. (DuBois 122) DuBois, chose to chal lenge Washington, who was seen by many as one of if not the most important black man of his time as a capitulator who chose to teach complacency over change. This is not DuBois telling a wrongful truth of the white race, it is him attacking a man of his own race for buying and selling the black man limitations rather than real fruits of freedom. In Washingtons own words there is a tell tale truth to Dubois frustration, with him and others who would continue to hold freed black men and women to standards that were not inclusive of their real abilities to progress. In the economy of God there is but one standard by which an individual can succeedthere is but one for a race. This country demands that every race shall measure itself by the American standard. By it a race must rise or fall, succeed or fail, and in the last analysis mere sentiment counts for little. During the next half century and more, my race must continue passing through the severe American crucible. We are to be tested in our patience, our forbearance, our perseverance, our power to endure wrong, to withstand temptations, to economize, to acquire and use skill; in our ability to compete, to succeed in commerce, to disregard the superficial for the real, the appearance for the substance, to be great and yet small, learned and yet simple, high and yet the servant of all. This, this is the passport to all that is best in the life of our republic, and the Negro must possess it, or be debarred. (Denton 189) According to Washington, Negroes in America must face the reality of the American system, work within it and stop or refrain from seeking higher (unreal) answers to their options to succeed. Washington believed that there would be a time when challenging these roles was an option, but right now blacks needed to suck it up and excel at what was offered them, trades. To DuBois, this was offensive, as it belittled blacks and gave them little if any hope for change, and any real fundamental application of the strides made from emancipation or the frustration of reconstruction. DuBois stresses that there are many who criticize Washingtons capitulation, but that he chooses not to, because there is danger in silence; But the hushing of the criticism of honest opponents is a dangerous thing. It leads some of the best of the critics to unfortunate silence and paralysis of effort, and others to burst into speech so passionately and intemperately as to lose listeners. (DuBois 124) DuBois, stres ses that he and other opponents of Washingtons policies and ideologies would like to see the silence end and the cry for and allowance of three essential things, for Blacks, in America 1. The right to vote. 2. Civic equality. And 3. The education of youth according to ability. (DuBois 128) Conclusion DuBois work The Souls of Black Folk is a fundamental document that should be read and understood by all who have any interest in black history and the way in which this history is portrayed. DuBois, unlike many mainline thinkers is demonstrative of a strong, educated black man worthy of praise and capable of intellectual musings regarding a whole group of people who were fundamentally silenced for most of their history in this nation. The use of the spiritual aspect as the thematic source of the work is also an essential strength, as even though many of DuBois words are wholly secular in nature the ideologies that he attests to should have a firm place in the spiritual character of hope, hope for change and hope for voice.

Glass-ceramics: Types, Technology and Application

Glass-ceramics: Types, Technology and Application CHAPTER 1 1. Introduction 1.1 Glass-ceramics Glass-ceramics are fine-grained polycrystalline materials formed when glasses of suitable compositions are heat treated and thus undergo controlled crystallisation to the lower energy, crystalline state. It must be emphasised here that only specific glass compositions are suitable precursors for glass-ceramics due to the fact that some glasses are too stable and difficult to crystallise whereas others result in undesirable microstructures by crystallising too readily in an uncontrollable manner. In addition, it must also be accentuated that in order for a suitable product to be attained, the heat-treatment is critical for the process and a range of generic heat treatment procedures are used which are meticulously developed and modified for a specific glass composition. A glass-ceramic is formed by the heat treatment of glass which results in crystallisation. Crystallisation of glasses is attributed to thermodynamic drives for reducing the Gibbs free energy, and the Amorphous Phase Separation (APS) which favours the crystallisation process by forming a nucleated phase easier than it would in the original glass. When a glass is melted, the liquid formed from the melting might spontaneously separate into two very viscous liquids or phases. By cooling the melt to a temperature below the glass transformation region it will result in the glass being phase separated and this is called liquid-liquid immiscibility. This occurs when both the phases are liquid. Hence a glass can simply be considered as a liquid which undergoes a demixing process when it cools. The immiscibility is either stable or metastable depending on whether the phase seperation occurs above or below the liquidus temperature respectively. The metastable immiscibility is much more inmporta nt and has two processes which then cause phase seperation and hence crystallisation; nucleation and crystal growth and spinodal decomposition. The first APS process has two distinguished stages; Nucleation (whereby the crystals will grow to a detectable size on the nucleus) and Crystal growth. Nucleation can either be homogeneous; where the crystals form spontaneously within the melt or heterogeneous; crystals form at a pre-existing surface such as that due to an impurity, crucible wall etc. Many a time the parent glass composition is specifically chosen to contain species which enhance internal nucleation which in the majority of cases is required. Such species also called nucleating agents can include metallic agents such as Ag, Pt and Pd or non-metallic agents such as TiO ­2, P2O5 and fluorides. The second process is spinodal decomposition which involves a gradual change in composition of the two phases until they reach the immiscibility boundary. As both the processes for APS are different, the glass formed will clearly result in having different morphology to each other. A glass-ceramic is usually not fully crystalline; with the microstructure being 50-95 volume % crystalline with the remainder being residual glass. When the glass undergoes heat treatment, one or more crystalline phases may form. Both the compositions of the crystalline and residual glass are different to the parent glass. In order for glass-ceramics having desirable properties to be developed, it is crucial to control the crystallisation process so that an even distribution of crystals can be formed. This is done by controlling the nucleation and crystal growth rate. The nucleation rate and crystal growth rate is a function of temperature and are accurately measured experimentally (Stookey 1959; McMillan 1979, Holand Beall 2002) The aim of the crystallisation process is to convert the glass into glass-ceramic which have properties superior to the parent glass. The glass-ceramic formed depends on efficient internal nucleation from controlled crystallisation which allows the development of fine, randomly oriented grains without voids, microcracks, or other porosity. This results in the glass-ceramic being much stronger, harder and more chemically stable than the parent glass. Glass-ceramics are characterised in terms of composition and microstructure as their properties depend on both of these. The ability of a glass to be formed as well as its degree of workability depends on the bulk composition which also determines the grouping of crystalline phases which consecutively govern the general physical and chemical characteristics, e.g. hardness, density, acid resistance, etc. As mentioned earlier, nucleating agents are used in order for internal nucleation to occur so that the glass-ceramic produced has desirable properties. Microstructure is the key to most mechanical and optical properties; it can promote or diminish the role of the key crystals in the glass-ceramic. The desirable properties obtained from glass-ceramics are crucial in order for them to have applications in the field of biomaterials. Glass-ceramics are used as biomaterials in two different fields: First, they are used as highly durable materials in restorative dentistry and second, they are applied as bioactive materials for the replacement of hard tissue. Dental restorative materials are materials which restore the natural tooth structure (both in shape and function), exhibit durability in the oral environment, exhibit high strength and are wear resistance. In order for dental restorative materials to restore the natural tooth structure, it is crucial to maintain the vitality of the tooth. . However non-vital teeth may also be treated with restorative materials to reconstruct or preserve the aesthetic and functional properties of the tooth. In order for glass-ceramics to be used for dental applications, they must possess high chemical durability, mechanical strength and toughness and should exhibit properties which mimic the natural tooth microstructure in order for it to be successful as an aesthetic. Glass-ceramics allow all these properties to be united within one material. As mentioned previously, for a glass-ceramic to have the desired properties, the glass is converted into a glass-ceramic via controlled crystallisation to achieve the crystal phase wanted and hence the desired properties it could possibly have. Hence, the glass-ceramic developed allows it to have properties such as low porosity, increased strength, durability, toughness etc which are crucial in the field of dental restorations as it prevents restorative failures which are mainly due to stress and porosity which causes cracks and hence failures. It took many years of research in order to get a material strong enough to be initially used as a dental reconstructive material. However over the past 10-15 years, research has progressed vastly and now glass-ceramics demonstrate good strength, high durability and good aesthetics. The development and processing of glass-ceramics has been focused on particular clinical applications, such as dental inlays, crowns, veneers, bridges and dental posts with abutments. Glass-ceramics are divided into seven types of materials: Mica glass-ceramics Mica apatite glass-ceramics Leucite glass-ceramics Leucite apatite glass-ceramics Lithium Disilicate glass-ceramics Apatite containing glass-ceramics ZrO2-containing glass-ceramics The first commercially usable glass ceramic products for restorative dentistry were composites of mica glass ceramics. Dicor ® and Dicor ® MGC were products based on these. According to the mechanism of controlled volume crystallisation of glasses, tetrasilicic micas, Mg2.5Si4O10F2, showing crystal sizes of 1 to 2 ÃŽ ¼m in the glass ceramic were produced. Dicor ® being amongst them was shaped by means of centrifugal casting methods to produce dental restorations such as dental crowns and inlays. Depending on the different crystal sizes and the corresponding microstructure of the glass ceramic, it was also possible to manufacture glass ceramics for machining applications. [53], Dicor ® MGC being amongst them. This resulted in the characteristic of good machinability in this type of glass-ceramic to be exploited and results concluded that crystals upto only 2 ÃŽ ¼m in length in the material improved mechanical strength over other materials. Mica-apatite glass-ceramics have been produced in the SiO2-Al2O3-Na2O-K2O-MgO-CaO-P2O5-F system. The main crystal phases are phlogopite, (K,Na)Mg3(AlSi3O10)F2  and fluorapatite, Ca5(PO4)3F. The base glass consists of three glass phases: a large droplet-shaped phosphate-rich phase, a small droplet-shaped silicate and a silicate glass matrix. Mica is formed during heat treatment, as in apatite-free glass-ceramics, by in-situ crystallization via the mechanism of volume crystallization. Apatite is formed within the phosphate-rich droplet phase. Astonishingly, every single apatite crystal possesses its own nucleation site in the form of a single phosphate drop. The glass-ceramic is biocompatible and suitable for applications in head and neck surgery as well as in the field of orthopaedics. Leucite glass-ceramics can be formed by applying the advantage of the viscous flow mechanism. IPS Empress ® is of this type of glass-ceramic. The material is processed by using the lost wax technique, whereby a wax pattern of the dental restoration such as an inlay, onlay, veneer or crown is produced and then put in a refractory die material. Then the wax is burnt out to create space to be filled by the glass-ceramic. As the glass-ceramic has a certain volume of glass phase, the principle of viscous flow can be applied and hence the material can be pressed into a mould. Surface crystallisation and surface nucleation mechanisms were controlled in order for this type of glass-ceramic to be formed. [42, 54] Consequently, the manufacturing of inlays and crowns developed due to the application of viscous flow mechanism of glass-ceramics in different shapes. The resulting leucite glass-ceramic restorations transluceny, colour and wear resistance behaviour can then be adjusted to those of natural tooth.[55] Additionally, the leucite glass-ceramic restorations can be produced by machining with CAD/CAM. IPS ProCAD ® and IPS Empress ® CAD are glass ceramics produced via this method. All leucite glass-ceramic restorations are bonded to the tooth structure with a luting material, preferably an adhesive bonding system. The retentive pattern produced on the glass-ceramic surface is particularly advantageous in this respect. It was possible to develop a leucite apatite glass-ceramic derived from the SiO2-Al2O3-Na2O-K2O-CaO-P2O5-F system by combining two different mechanisms, i.e. controlled surface nucleation and controlled bulk nucleation. IPS d.SIGN ® is amongst these. The glass-ceramic was prepared according to the classic method of glass-ceramic formation: melting, casting to prepare a glass frit, controlled nucleation and crystallization. A two-fold reaction mechanism leads to the precipitation of fluoroapatite, Ca5(PO4)3F and leucite, KAlSi2O6 [42]. SEM pictures show the two-phase crystal content of apatite and leucite in this type of glass-ceramic. Fluoroapatite phase takes the form of needle-shaped crystals whereas the oval areas are the leucite crystals. The clinical application of this glass-ceramic has been proven to be suitable for clinical application as veneering material on metal frameworks for single units as well as for large dental bridges involving more than three units. The first glass-ceramic to be developed was by Stookey et al (1959) which contained Lithium disilicate. [37]. Further research into this field allowed for IPS Empress ®2 to be developed. This glass-ceramic was developed in order to extend the range of indications of glass-ceramics from inlay and crowns to three-unit bridges, by offering high strength, high fracture toughness and at the same time, a high degree of translucency. Both the flexural strength and fracture toughness of lithium disilicate glass-ceramics are almost three times of those of leucite glass-ceramics. Lithium disilicate glass-ceramic ingot are utilizied to produce the crown or bridge framework in combination with the viscous flow process. To further improve the aesthetic properties, i.e. translucency and shade match, and to optimally adjust the wear behaviour to that of the natural tooth, the lithium disilicate glass ceramic is veneered with an apatite-containing glass-ceramic using a sintering process. In order to meet the demanding requirements of CAD/CAM applications, a lithium metasilicate glassceramic, IPS e.max ®was developed. This material, which is supplied in a typically blue colour, is adjusted by thermal treatment in order to demonstrate a characteristic tooth colour. The range of IPS e.max ®products also encompasses various apatite-containing glass ceramics that are suitable for both layering material on lithium disilicate glass-ceramic and veneering material on ZrO2 sintered ceramic. The apatite crystal phase of the Ca5(PO4)3F type acts as a component that adjusts the optical properties of the restoration to natural tooth. For this reason, the crystallites are of nanoscale dimension. ZrO2 containing glass-ceramics was the first glass-ceramic developed to be fused to high strength ZrO2 ceramic dental posts. The glass-ceramic contains Li12ZrSi6O15 crystals as the main phase; however different types of crystals are also precipitated in the glassy matrix. ZrO2 has become very interesting not only in the field of medicine but also in dental applications. High-strength and high toughness dental posts, crowns and bridges can be prepared from this material. In order for a dental restorative material to be of clinical success, their most important properties include; high strength, high toughness, abrasion behaviour comparable to natural teeth, translucency, colour, durability) and the processing technologies (moulding, machining, sintering). [56] Furthermore, the material should have good marginal fit with the tooth, biocompatibility, good mechanical properties and low porosity. In addition to the aforementioned properties, the recent requirement for dental restorative materials is for its appearance to be similar to that of a natural tooth. Glass-ceramics have been researched immensely in order to fulfil high standards of function and aesthetics from an early stage. The trend for metal free dental restorations began from the 1970s whereby metal free feldspathic ceramics were reinforced with additional components. Since then, increasing the strength of these materials progressed rapidly by controlling the nucleation and crystallisation of glasses, as discussed earlier. These developments have now led to the introduction of a trend which is focused on achieving exceptional aesthetic results with glass ceramics as metal free dental restorations. Although glass-ceramics exhibit the desired properties for dental restoration, their main drawback is that they are brittle which the main cause of failure is. This is due to either fabrication defects; which are created during production of the glass-ceramic or secondly, surface cracks; which are due to machining or grinding. Therefore when processing the glass-ceramic, care needs to be taken in addition to choosing the suitable method for production for specific compositions of the glass-ceramic in order to improve their mechanical properties. Apart from the use of glass-ceramics for dental restorations, they can also be applied as bioactive materials for the replacement of hard tissue. Bone is a complex living tissue which has an elegant structure at a range of different hierarchical scales. It is basically a composite comprising collagen, calcium phosphate (being in the form of crystallised hydroxyapatite, HA or amorphous calcium phosphate, ACP) and water. Additionally, other organic materials, such as proteins, polysaccharides, and lipids are also present in small quantities. Because bone is susceptible to fracture; there has always been a need, since the earliest time, for the repair of damaged hard tissue. Many years of research has attempted to use biomaterials to replace hard tissue, ranging from using bioinert materials, to bioactive materials such as ‘Bioglass (Hench et al) to ‘Apatite-wollastonite (A-W) glass-ceramics (Kokubo et al) and to calcium phosphate materials. Calcium phosphate based materials have received a great deal of attention in this field due to their similarity with the mineral phase of bone. 1.2 Calcium Phosphate Glasses The application of calcium phosphate material as a bone substitute began by Albee (1920), who reported that a tricalcium phosphate compound used in a bony defect promoted osteogenesis. Many years later, Levitt et al (1969) [65] and Monroe et al (1971) were the first to suggest the use of calcium phosphate ceramics for dental and medical implant materials. Subsequently in 1971, Hench et al developed a calcium phosphate containing glass-ceramic, called Bioglass ® and demonstrated that it chemically bonded with the host bone through a calcium phosphate rich layer. Furthermore the advantageous properties of calcium phosphate ceramics arose when Nery et al (1975) used a calcium phosphate ceramic for implants in surgically produced infrabony defects in dogs. This demonstrated that the calcium phosphate ceramic was nontoxic, biocompatible, and caused no significant haematological changes in the calcium and phosphorus levels. Since then, a great deal of research into calcium phosphate glas s-ceramics has been conducted as potentially bone substitutes in dentistry. Calcium phosphate based ceramics can be characterised accordingly; Hydroxyapatite (HA, Ca5(PO4)3OH) ÃŽ ²-tricalcium phosphate (ÃŽ ²-TCP, ÃŽ ²-Ca3(PO4)2) Biphasic calcium phosphates, BCP; mixture of HA and ÃŽ ²-TCP ÃŽ ²-calcium pyrophosphate (ÃŽ ²-CPP, ÃŽ ²-Ca2P2O7) Fluorapatite (FAP, Ca5(PO4)3F) Calcium phosphate based ceramics and their properties have been characterised according to the proportion of calcium to phosphorus ions in the structure. One of the most widely used synthetic calcium phosphate ceramics is hydroxyapatite, Ca5(PO4)3OH, HA and this is due to its chemical similarities to the inorganic component of hard tissues. HA, has a Ca:P molar ratio of 1.67. It has higher stability in aqueous media than other calcium phosphate ceramics. Tricalcium phosphate (TCP) is a biodegradable bioceramic with the chemical formula, Ca3(PO4)2. TCP dissolves in physiological media and can be replaced by bone during implantation. TCP has four polymorphs, the most common ones being ÃŽ ± and ÃŽ ²-forms, of which ÃŽ ²-TCP has received a lot of attention in the field of bone substitutes. Slight imbalances in the ratio of Ca:P can lead to the appearance of extraneous phases. If the Ca:P ratio is lower than 1.67, then alpha- or beta tricalcium phosphate may be present after processing. If the Ca:P is higher than 1.67, calcium oxide (CaO) may be present along with the HA phase. These extraneous phases may adversely affect the biological response to the implant in-vivo. A TCP with a Ca:P ratio of 1.5 is more rapidly resorbed than HA. Hence, ÃŽ ²-TCP has been involved in recent developments aimed to improving its biological efficiency and its mechanical properties in order for it to be successful as bone substitutes. Mixtures of HA and TCP, known as biphasic calcium phosphate (BCP), have also been investigated as bone substitutes and the higher the TCP content in BCP, the higher the dissolution rate. The crystal structure of HA can accommodate substitutions by various other ions for the Ca2+, PO43− and OH− groups. The ionic substitutions can affect the lattice parameters, crystal morphology, crystallinity, solubility and thermal stability of HA. Anionic substitutions can either occur in the phosphate- or hydroxyl positions. Fluorapatite and chlorapatite are common examples of anionically substituted HA. They display a similar structure to HA, but the F− and Cl− ions substitute for OH−. A lot of research has gone into carbonate substituted HA and it has shown to have increased bioactivity compared to pure HA, which is attributed to the greater solubility of the carbonated substituted HA. Thus, recent work has been in progress in order to optimise the production and sintering behaviour of carbonated substituted HA in order for use in biomedical applications. Materials which are bioactive i.e. the ability to bond to living tissue and enhance bone formation, have the following characteristic compositional features: (i) SiO2 contents smaller than 60 mol%, (ii) high Na2O and CaO content, and (iii) high CaO:P2O5 ratio [80]. Although silica based bioactive materials have shown great clinical success in many dental and orthopaedic applications, its insoluble properties has resulted in it as a potential for a long term device and the long term reaction to silica, both locally and systematically is still unknown. [81] Therefore, silica free, calcium phosphate glasses have attracted much interest due to their chemical and physical properties. They offer a more controlled rate of dissolution compared to silica containing glasses, they are simple, easy to produce, biodegradable, biocompatible, bioresorbable due to their ability to completely dissolve in an aqueous environment and have excellent bioactivity, osteoconductivity as well as not causing a n inflammatory response. Due to their properties, especially due to it being bioresorbable, calcium phosphate glasses have been under investigation for several applications in the dental field, particular as implants. However only certain calcium phosphate compounds are suitable for implantation in the body, compounds with a Ca:P ratio less than 1 are not suitable for biological implantation due to their high solubility. The structural unit of phosphate glasses is a PO4 ­ tetrahedron. The basic phosphate tetrahedra form long chains and rings that create the three-dimensional vitreous network. All oxygens in the glass structure are bridging oxygens (BO), and the non-bridging oxygens (NBO) can be formed by including other species such as CaO and Na2O or MgO. Do to the effects of Ca2+, Na2+ ­ and Mg2+ in the glass structure; they are defined as glass network modifiers, which form the glassy state and are called ‘invert glasses. Hence the structure of phosphate glasses can be described using the Qn terminology, where n represents the number of bridging oxygens that a PO4 tetrahedron has in a P2O5 glass, every tetrahedron can bond at three corners producing layers of oxygen polyhedra which are connected together with Van der Waals bonds. When the PO4 tetrahedron bonds with three bridging oxygens, giving the Q3 species, it is referred to as an ultraphosphate glass, which usually consists of a 2D network. When it bonds to two bridging oxygens, usually in a 3D-network it gives the Q2 species, it is referred to as metaphosphate glass. Further addition gives Q1 species, also called pyrophosphate glass, which bonds only to one bridging oxygen. Finally, the Q0 species do not bond to any bridging oxygen and hence is known as an orthophosphate glass. [14] A large number of calcium phosphate glass compositions have been studied in order to exhibit suitable properties for use in biomedical applications until now, and they can be categorised into four groups: Calcium phosphate glasses containing Potassium Calcium phosphate glasses containing Magnesium Calcium phosphate glasses containing Sodium and Titania Calcium phosphate glasses containing Fluorine and Titania 1) Calcium phosphate glasses containing Potassium: Dias et al (2003) [12] conducted a study and prepared bioresorbable calcium phosphate glass-ceramics between the metaphosphate and pyrophosphate region based on the composition 45CaO-45P2O5-5K ­2 ­O-5MgO (Ca:P = 0.5). XRD results showed that addition of nucleating agents, K2O and MgO forms bioactive: ÃŽ ²-CPP and biodegradable phases: KCa(PO3)3, Ca4P6O19 as well as ÃŽ ²-Ca(PO3)2 which is considered to be non-toxic.[21] DTA results showed two crystallisation peaks, Tp at 627 °C and 739 °C and two melting temperatures, Tm at 773 °C and 896 °C which was thought to be due to the partial melting of the crystalline phases or residual glass matrix. The glass transition temperature, Tg was observed at 534 °C. FTIR results showed functional groups corresponding to metaphosphate and pyrophosphate, (PO3)- and (P2O7)4-. These results are in accordance with functional groups of the crystalline phases identified by XRD: ÃŽ ²-CPP, KCa(PO3)3, Ca4P6O19 and ÃŽ ²-Ca(PO3)2. Results from de gradation studies of these glass-ceramics confirmed that by controlling the overall composition of the O:P in the glass, glass ceramics with high degree of degradability can be obtained. The level of chemical degradation observed for these materials is well-above that reported in literature for bioactive ceramics that are clinically used, namely HA and TCP. It was therefore concluded that the incorporation of K2O in glass ceramics increases the solubility and also these calcium phosphate glass ceramics makes them potentially clinically helpful for promoting the regeneration of soft as well as hard connective tissue by allowing the degradability to be controlled. A study by Knowles et al (2001) [92] investigated the solubility and the effect of K2O in the glass-system based on the general composition: K ­2 ­O-Na2O-CaO-P2O5. The exchange of a mono or divalent ion with another of a similar charge was therefore investigated. The P2O5 and CaO content were fixed, at 45 mol% and the CaO content at 20, 24 or 28 mol% and the ratio of K2O to Na2O was varied from 0 to 25mol %. Results showed, firstly an increase in CaO content caused the solubility to decrease, as expected and confirmed from previous studies. [81,94] Secondly, for all CaO contents there was an increase in solubility, when K2O content was increased. [92] In a recent study by Marikani et al (2008), based on the same general composition, they demonstrated that the addition of K2O caused a decrease in both density (from 2.635 g cm-3 to 2.715 g cm -3 and microhardness measurements (from 257 to 335 HV) and hence weakens the structure. These findings are attributed to the replacement of l ighter cation (Na2O) by a heavier one (K2O). The ionic radius of potassium is larger than the ionic radius of sodium so, the addition of K2O has a larger disrupting effect on the structure and hence weakens the glass-network. The decrease of melting point with the addition of K2O content indicates that K2O increases network disruption by producing non-bridging oxygens. And the low value of Tg indicates that the glass samples are thermally unstable. Additionally, the elastic modulus, decreases when the concentration of K2O is increased, which implies the weakening of the overall bonding strength, as more cross linking is degraded. The increase of the internal friction and the decrease of the thermal expansion coefficient with the addition of the K2O content are due to the formation of non-bridging oxygen ions. The SEM micrographs of the glass samples recorded before immersion in SBF indicates the amorphous nature of the materials and when glasses were immersed in SBF solutions for 10 days, the glass-samples showed bioactivity. Although the addition of K2O to the ternary Na2O-CaO-P2O5 based system offers greater flexibility in terms of tailoring the solubility to suit potential biomedical applications, only little research has been conducted in using K2O in calcium phosphate glasses, probably because it has shown to increase network disruption which was confirmed by decrease in Tm, addition of K2O causes a decrease in density and microhardness measurements, it weakens overall bonding strength confirmed by a decrease in the elastic modulus, causing it to be less rigid as well as producing thermally unstable glasses which was confirmed by the low values of Tg. These mechanical properties are not desirable in the long run and due to it being less rigid, it would not withstand stress in biomedical applications and consequently result in failure. 2) Calcium phosphate glasses containing Magnesium: Research into calcium phosphate glasses which produce biocompatible and bioactive phases has generated a lot of interest. An attempt to induce ÃŽ ²-TCP was undertaken by Zhang et al (2000) on calcium phosphate glass-ceramics in the pyrophosphate region based on the composition 50CaO-40P2O5-7TiO2-1.5MgO-1.5Na2O (Ca:P molar ratio = 0.625). XRD results showed that the ÃŽ ²-TCP phase was not detected and the main crystalline phase precipitated was ÃŽ ²-CPP with smaller amounts of soluble Calcium titanophosphate, CaTi4(PO4)6 CTP, and Sodium titanophosphate, NaTi2(PO4)3. Kasuga et al (1998) reported a similar occurrence in the structure of glass-ceramics which contained TiO2 (wt 3 %). . SEM observations demonstrated light areas which were confirmed by EDS analysis to be ÃŽ ²-CPP, grey areas was thought to correspond to Na- containing phases and dark areas were composed of lower CaO contents compared to the other two areas and contained MgO and Na2O. These results were identical to Kasuga et als study (1999). The undetectable ÃŽ ²-TCP phase was possibly due to the low content of MgO and TiO2 added and the low Ca:P ratio of the glass. Although bioactive and biosoluble phases were precipitated in the glass-ceramic, no continuous apatite layer was formed even after 8 weeks of immersion in SBF solution. A study by Brauer et al (2007) observed the solubility of several phosphate glasses in the system P2O5-CaO-MgO-Na2O-TiO2. The glass compositions ranged from ultraphosphate glasses (with phosphate contents over 50 mol %) to polyphosphate glasses (containing 50 mol% P2O5 or less which are formed by phosphate chains or rings possessing different chain lengths) to invert glasses (pyrophosphate glasses- P2O5 concentrations of around 34 mol %.). Results showed that the phosphate glasses showed a uniform dissolution. No selective alkali leaching, which is known from silica based glasses, was observed. Also that the solubility of the glasses strongly depend on the glass-composition. The higher the phosphate content resulted in an increase in solubility; According to Vogel et al [104], this is due to the polymerisation of the phosphate chains and the Q1 end units being more susceptible to hydration and subsequent hydrolysis than Q2 middle groups. Also it was observed that the higher the conce ntration of Na2O resulted in an increase in solubility too due to the effect Na+ has on the glass structure. Addition of titanium oxide resulted in a decrease in both the solubility and the tendency of the glasses to crystallise by forming cross links between phosphate groups and titanium ions. Invert glasses showed a considerably smaller solubility than polyphosphate glasses and offer an alternative to polyphosphate glasses, since they are more stable to moisture attack. However, decreasing the P2O5 content makes glasses not only more stable to hydrolysis but also restricts the glass forming area. Hence, glasses in the pyrophosphate region show a larger tendency to crystallize than polyphosphate glasses [96]. However invert glasses in the system P2O5-CaO-MgO-Na2O showed that properties such as solubility and crystallization tendency can be controlled by adding small amounts of metal oxides [95]. Results of solubility experiments showed that the glass system investigated enabled adj ustment of solubility with only minor chemical changes. This ability to control the solubility is very promising for medical application where the coordination of implant degradation and bone formation are a key issue. A study by Dias et al (2005) studied the crystallisation of the glass-system: 37P2O5-45CaO-5MgO-13TiO2 (Ca:P=0.6)in the pyrophosphate and orthophosphate region, by using TiO2 as a nucleating agent and MgO as a network modifier. Results showed that they contained four different crystalline phases; two of them, ÃŽ ²-CPP and CTP are reported to be biocompatible and bioactive, respectively [88,97,98]. T

Ribozymes Essay -- Biology, Catalytic Molecules, RNA

Ribozymes are catalytic molecules that cleave the ribonucleic acid (RNA) at specific sequences (Gesteland et al. 2006). RNA is the nucleic acid that is made in the process of transcription; when the deoxyribonucleic acid (DNA) anneals, it transcribes itself into a linear stranded molecule called RNA. In order for RNA to synthesise proteins, it requires catalytic enzymes to perform certain chemical reactions. In the past, it was thought that all chemical reactions are catalysed by protein enzymes; however, in the eighties this hypothesis was disproved as Thomas Cech and Sydney Altman discovered that RNA is able to carry out self-catalysing activities which were named as ribozymes because they perform similar functions as the protein enzymes (Jaeger, 1997). Even though, RNA ribozymes lack the functional groups diversity found in protein enzymes, they are able to carry out their own catalytic reactions due to their tendency to fold into a 3D structure and form helices by Watson-Crick ba se pairing role (Kiehntopf et al. 1995). Ribozymes are now play critical role in the understanding of biochemistry, as they have the ability to catalyse some of the most important chemical reactions such as RNA splicing as well as the synthesis of peptides, for instance ribozymes can speed up the phosphoryl transfer chemical reactions by 1011 folds. This review will describe the structure, sources and applications of ribozymes. There are several naturally occurring ribozymes that have been identified to date; these are divided into three distinct classes. Firstly, the self splicing introns that fall into groups I and II respectively depending on their structure and the recognition sequences. Self splicing group I intron was the first ribozyme to b... ...the cells, the localisation of the ribozymes in the cells as well as the selection site of the messengerRNA (James and Gibson, 1998). Ribozymes are currently considered to hold many promises for the future development of gene therapy as they have the ability to splice and cleave any target RNA sequences. There are seven natural ribozymes known and several artificial ribozymes have been created. These artificial ribozymes are being used as therapeutic agent to target the aberrant gene expression in many lethal diseases such as cancer. The limitation of artificial ribozymes is mainly due to the difficulty in their delivery to the target cells. Therefore, more research needs to be conducted in thoroughly studying the organisation and structures of the natural RNA ribozymes to achieve successful artificial ribozymes that have complex function in the future.

The Complex Relationship Between Multiculturalism and Feminism Essay

The Complex Relationship Between Multiculturalism and Feminism These days, it seems that multiculturalism is generally an assumed good. Increased acknowledgement of diversity and cultural sensitivity seem to be steps toward leveling the playing field for all human beings. And that is the goal of much scholarship and activism, right--to secure and ensure human rights across the board? That is one of global feminism’s aims, so it would seem that multiculturalism would help, not hinder, feminist work to better the situation of women. That is not necessarily the case. It may be helpful to first clarify what is meant by both feminism and multiculturalism. Though it is difficult to definitively state what is meant by these complex terms, Susan Moller Okin is able to sum up the essence of feminism and single out a facet of multiculturalism that is particularly relevant. In her essay, â€Å"Is Multiculturalism Bad for Women?,† Okin explores the relationship between feminism and multiculturalism, especially pertaining to the granting of â€Å"group rights.† Okin writes: â€Å"By feminism, I mean the belief that women should not be disadvantaged by their sex, that they should be recognized as having human dignity equal to that of men, and that they should have the opportunity to live as fulfilling and as freely chosen lives as men can.† She goes on, writing that â€Å"Multiculturalism is harder to pin down, but the particular aspect that concerns me here is the claim, made in the context of basically liberal democracies, that minority cultures or ways of life are not sufficiently protected by the practice of ensuring the individual rights of their members, and as a consequence these should also be protected through special group rights of priv... ...a hard time representing our entire country’s population in a few sentences, or even a few pages. The American cultural system of today is far different than the culture of the 1940’s, and my experience as a Southerner is quite different than that of someone from New England. Multiculturalism seeks to protect cultures from extinction, it is very dangerous to over-simplify a complex cultural system and identify it by its most extreme practices. Feminism and multiculturalism do have some of the same goals; chiefly, equality of rights for all human beings. It is true that some efforts of multiculturalism counter feminism’s goals to empower women, but I do not think that this must always be the case. Cultural sensitivity is not enough; we must consider cultural practices, the workings of the cultural system that supports them, and how that system itself came about.