Art work Essay Example | Topics and Well Written Essays - 250 words - 1

Art work - Essay Example It belongs to the Metropolitan museum of Art. The credit line to this piece of art belongs to George A. Hearn Fund, 1957. Judging from this piece, I get to realize that Jackson Pollock was a prime champion of his time.by standing before this abstract painting and many others that he has done, one can observe his level of fineness. One immediately realizes that he was the greatest painter America ever produced. My attraction and appreciation of this piece shows my love for abstract painting. My desire to produce such fine work is engraved to the feeling of desire to achieve the levels of success that Jackson did. It also shows my belief in expressing emotions efficiently through abstract painting. The metropolitan museum of art. Autumn Rhythm (Number 30) Jackson Pollock  (American, Cody, Wyoming 1912–1956 East Hampton, New York): retrieved from http://www.metmuseum.org/Collections/search-the-collections/210009206. Retrieved on

Nursing Research and Evidence-Based Practice Essay Example for Free

Nursing Research and Evidence-Based Practice Essay I did not understand why I had to take a research class when all I wanted to do was be a staff nurse in a critical care unit. Research? Evidence-based practice? Why are these topics in the nursing program? I have enough to do just learning all the content in my clinical courses. What do research and evidence have to do with developing my nursing abilities? I trust the faculty, the textbooks, and clinical experience to prepare me for nursing. I’m already getting what I need to know. That was my earlier attitude. Now that I am practicing, I have a new appreciation for nursing research and the evidence it provides for application to practice. I have an entirely different way of addressing clinical questions. I’m starting to ask questions about how I can improve the care I give to patients and how I can be involved in my workplace’s efforts to improve care for the patients it serves. I have discovered by purposeful reading in my practice area that research reports and research summaries contain many implications that apply to practice in the critical care unit.  ¦ QUESTIONS TO CONSIDER WHILE READING THIS CHAPTER: 1 How can faculty encourage students to read research journals? 2 How does research affect nursing practice? 3 How can nurses motivate colleagues to base their practice on research? KEY TERMS Clinical nurse researcher (CNR) An advanced practice nurse who is doctorally prepared and directs and participates in clinical research. Clinical nurse specialist (CNS) An advanced practice nurse who provides direct care to clients and participates in health education and research. Clinical practice guideline (CPG) an evidence-based guide to clinical practice developed by experts in a particular ? eld for direct application in clinical environments. Control group Subjects in an experiment who do not receive the experimental treatment and whose performance provides a baseline against which the effects of the treatment can be measured. When a true experimental design is not used, this group is usually called a comparison group. Data collection The process of acquiring existing information or developing new information. 104 Nursing Research and Evidence-Based Practice CHAPTER 6 105 Empirical Having a foundation based on data gathered through the senses (e. g. , observation or experience) rather than purely through theorizing or logic. Ethnography A qualitative research method for the purpose of investigating cultures that involves data collection, description, and analysis of data to develop a theory of cultural behavior. Evidence-based practice The process of systematically ? nding, appraising, and using research ? ndings as the basis for clinical practice. Experimental design A design that includes randomization, a control group, and manipulation between or among variables to examine probability and causality among selected variables for the purpose of predicting and controlling phenomena. Generalizability The inference that ? ndings can be generalized from the sample to the entire population. Grant Proposal developed to seek research funding from private or public agencies. Grounded theory A qualitative research design used to collect and analyze data with the aim of developing theories grounded in real-world observations. This method is used to study a social process. Meta-analysis Quantitative merging of ? ndings from several studies to determine what is known about a phenomenon. Methodologic design A research design used to develop the validity and reliability of instruments that measure research concepts and variables. Naturalistic paradigm A holistic view of nature and the direction of science that guides qualitative research. Needs assessment A study in which the researcher collects data for estimating the needs of a group, usually for resource allocation. Phenomenology A qualitative research design that uses inductive descriptive methodology to describe the lived experiences of study participants. Pilot study A smaller version of a proposed study conducted to develop or re? ne methodology, such as treatment, instruments, or data collection process to be used in a larger study. Qualitative research A systematic, subjective approach used to describe life experiences and give them meaning. Quantitative research A formal, objective, systematic process used to describe and test relationships and examine cause-and-effect interactions among variables. Quasi-experimental research A type of quantitative research study design that lacks one of the components (randomization, control group, manipulation of one or more variables) of an experimental design. Randomization The assignment of subjects to treatment conditions in a random manner (determined by chance alone). Secondary analysis A research design in which data previously collected in another study are analyzed. State-of-the-science summary A merging of ? ndings from several studies concerning the same topic. Examples include meta-analysis with a quantitative approach and integrative review with a descriptive approach. Survey A nonexperimental research design that focuses on obtaining information regarding the status quo of a situation, often through direct questioning of participants. Triangulation The use of a variety of methods to collect data on the same concept. LEARNING OUTCOMES After studying this chapter, the reader will be able to: 1 Summarize major points in the evolution of nursing research in relation to contemporary nursing. 2 Evaluate the in? uence of nursing research on current nursing and health care practices. 3 Differentiate among nursing research methods. 4 Evaluate the quality of research studies using established criteria. 5 Participate in the research process. 6 Use research ? ndings to improve nursing practice. 106 UNIT ONE The Development of Nursing CHAPTER OVERVIEW This chapter provides basic knowledge regarding the research process and the ultimate importance of evidence-based nursing practice. The intent is to inspire an appreciation for nursing research and to show how it can improve nursing practice and how results can be translated into health policy. Nursing research is de? ned as a systematic approach used to examine phenomena important to nursing and nurses. A summary of major points in the evolution of nursing research in relation to contemporary nursing is presented. A description of private and public organizations that fund research is given, and their research priorities are listed. Major research designs are brie? y described, and examples of each are given. Nurses of all educational levels are encouraged to participate in and promote nursing research at varying degrees. The process of locating research and evidence for practice is reviewed. Students are introduced to the research process and guided in the process of critically appraising published research and research syntheses. Ethical issues related to research are examined, and historical examples of unethical research are given. The functions of the institutional review board (IRB) and the use of informed consent in protecting the rights of human subjects are emphasized. DEFINITION OF NURSING RESEARCH Research is a process of systematic inquiry or study to build knowledge in a discipline. The purpose of research is to develop an empirical body of knowledge for a discipline or profession. Speci? cally, research validates and re? nes existing knowledge and develops new knowledge (Burns and Grove, 2007). The results of research process provide a foundation on which practice decisions and behaviors are laid. Research results create a strong scienti? c base for nursing practice, especially when deliberately and carefully evaluated for application to speci? c clinical topics (Melnyk and Fineout-Overholt, 2005). In recent decades the nursing discipline has begun to pay much greater attention to the necessity of participating in research. Nursing research is a systematic approach used to examine phenomena important to nursing and nurses. Because nursing is a practice profession, it is important that clinical practice be based on scienti? c knowledge. Evidence generated by nursing research provides support for the quality and cost-effectiveness of nursing interventions. Thus recipients of health care—and particularly nursing care—reap bene? ts when nurses attend to research evidence and introduce change based on that evidence into nursing practice. The introduction of evidence-based change into the direct provision of nursing care may occur at the individual level of a particular nurse or at varied organizational or social levels. In addition to nursing research aimed at affecting the direct provision of nursing and health care to recipients of nursing care, nursing research also is needed to generate knowledge in areas that affect nursing care processes indirectly. Research within the realms of nursing education, nursing administration, health services, characteristics of nurses, and nursing roles provides evidence for effectively changing these supporting areas of nursing knowledge (Burns and Grove, 2007). Today the importance of nursing research to the discipline is recognized. However, much nursing history underlies the current state of acceptance. EVOLUTION OF NURSING RESEARCH Nursing research began with the work of Florence Nightingale during the Crimean War. After Florence Nightingale’s work, the pattern that nursing research followed was closely related to the problems confronting nurses. For example, nursing education was the focus of most research studies between 1900 and 1940. As more nurses received their education Nursing Research and Evidence-Based Practice CHAPTER 6 107 in a university setting, studies regarding student characteristics and satisfactions were conducted. As more nurses pursued a college education, staf? ng patterns in hospitals changed because students were not as readily available as when more students were enrolled in hospitalaf? liated diploma programs. During this period, researchers became interested in studying nurses. Questions such as what type of person enters nursing and how are nurses perceived by other groups guided research investigations. Teaching, administration, and curriculum were studies that dominated nursing research until the 1970s. By the 1970s more doctorally prepared nurses were conducting research, and there was a shift to studies that focused on the improvement of patient care. The 1980s brought nursing research to a new stage of development. There were many more quali? ed nurse researchers than ever, widespread availability of computers for collection and analysis of data, and a realization that research is a vital part of professional nursing (Polit and Beck, 2006). Nurse researchers began conducting studies based on the naturalistic paradigm. These studies were qualitative rather than quantitative. In addition, instead of conducting many small, unrelated research studies, teams of researchers, often interdisciplinary, began conducting programs of research to build bodies of knowledge related to speci? c topics, such as urinary incontinence, decubitus ulcers, pain, and quality of life. The 1990s brought increasing concern about health care reform, and now in the twenty-? rst century, research studies focus on important health care delivery issues, such as cost, quality, and access. Research ? ndings are being used increasingly as the basis for clinical decisions. Evidencebased practice (EBP) can be de? ned as the process of systematically ? nding, appraising, and using research ? ndings as a basis for making decisions about patient care. The rise of technology and the worldwide access and ? ow of information have transformed the decision-making processes of practitioners. Helpful informational websites for busy practitioners are listed in Box 6-1. No longer do nurses simply compare outcomes of patient care with other units in the B O X 6–1 Helpful Websites l f l b i National Guideline Clearinghouse—resource for evidence-based clinical practice guidelines www. guidelines. gov US Department of Veterans Affairs Clinical Practice Guidelines www. healthquality. va. gov AHRQ Healthcare Innovations Exchange—innovations and tools to improve health care www. innovations. ahrq. gov/index. aspx The Evidence-Based Medicine Education Center of Excellence—extensive list of databases, journals, and textbooks http://library. ncahec. net/ebm/pages/resources. htm U. S. National Institute for Health Consensus statements http://consensus. nih. gov Centre for Evidence-Based Nursing, based at University of York—United Kingdom www. york. ac. uk/healthsciences/centres/evidence/cebn. htm The Joanna Briggs Institute, based at Royal Adelaide Hospital and the University of Adelaide, Australia—multiple evidence resources for practice www. joannabriggs. edu. au Cochrane Center—resource for evidence-based clinical practice guidelines www. cochrane. org 108 UNIT ONE The Development of Nursing same hospital. Nurses and other health care professionals are more likely to look for solutions, choices, and outcomes for patients that represent the best available knowledge internationally (Hamer and Collinson, 2005). RESEARCH PRIORITIES Why set priorities for research in the nursing discipline? Can nurses do research in areas that match personal areas of interest? The answer to the second question is, yes, certainly. But nursing exists to provide high-quality nursing care to individuals in need of health-promoting, health-sustaining, and health-restoring strategies. The main outcome of research activity for a nurse is to eventually put the knowledge gained to work in health care delivery. Research priorities, often set by groups that fund research, encourage nurse researchers to invest effort and money into those areas of research likely to generate the most bene? t to recipients of care. Of course the funding opportunities offered by such groups do not hurt the research enterprise either. Research costs money. Thus nurses engaged in research often match personal interests with funding opportunities that are available during the planning phase for a proposed investigation. Two major sources of funding for nursing research are the National Institute of Nursing Research (NINR) and the Agency for Healthcare Research and Quality (AHRQ) (formerly known as the Agency for Health Care Policy and Research [AHCPR] and reauthorized as AHRQ by Congress in 1999). Both of these organizations are funded by federal congressional appropriations. Private foundations and nursing organizations also provide funding for nursing research. National Institute of Nursing Research As part of the National Institutes of Health (NIH), the NINR supports research on the biologic and behavioral aspects of critical health problems that confront the nation. The NINR’s research focus encompasses â€Å"health promotion and disease prevention, quality of life, health disparities, and end-of-life† (NINR Strategic Plan 2006-2010, 2006). A small sampling of potentially supported research topics includes those aimed at: ? Determining disease risk and treatment through utilizing genetic information ? Determining effective health-promotion strategies for individuals, families, and communities ? Discovering approaches that encourage people to effectively take responsibility for symptom management and health promotion ? Assisting in identi? cation and effective management of symptoms related to acute and chronic disease ? Improving clinical settings in which care is provided ? Improving the quality of care giving in settings such as long-term care facilities, the home, and the community ? Understanding predisposition to disease, socioeconomic factors that in? uence health, and cultural health practices that either protect from or expose to risk for health problems ? Improving symptom management for those at end of life The areas of research emphasis published by the NINR are useful guides for investigators developing proposals but are not considered to be prescriptive in nature. Investigators bring to bear their own unique expertise and creativity when proposing research in harmony with NINR priority research areas. Annually the NINR conducts a roundtable discussion with multiple nursing organizations to obtain the feedback of the disciplines regarding the need for continued or new research Nursing Research and Evidence-Based Practice CHAPTER 6 109 emphases. Information obtained is used in setting future research agendas and making decisions about funding of proposals submitted by researchers (Of? ce of Science Policy and Public Liaison, NINR, 2009). The NINR website details current announcements regarding research priorities (www. ninr. nih. gov/ResearchAndFunding). Agency for Healthcare Research and Quality The AHRQ broadly de? nes its mission as â€Å"improving the quality, safety, ef? ciency, and effectiveness of health care for all Americans† (AHRQ, 2009a). As an agency of the U. S. Department of Health and Human Services, the AHRQ’s health-related aims are to reduce the risk of harm by promoting delivery of the best possible health care, improve health care outcomes by encouraging the use of evidence to make informed health care decisions, transform research into practice to facilitate wider access to effective health care services, and reduce unnecessary costs (AHRQ, 2009a). Since the inception of the agency in 1989, strategic goals have centered on supporting improvements in health outcomes, strengthening measurement of health care quality indicators, and fostering access to and cost-effectiveness of health care. The 1999 reauthorizing legislation expanded the role of the agency by directing the AHRQ to: ? Improve the quality of health care through scienti? c inquiry, dissemination of ? ndings, and facilitation of public access to information. ? Promote patient safety and reduce medical errors through scienti? c inquiry, building partnerships with health care providers, and establishment of centers for education and research on therapeutics (CERTs). ? Advance the use of information technology for coordinating patient care and conducting quality and outcomes research. ? Establish an of? ce on priority populations to ensure that the needs of low-income groups, minorities, women, children, the elderly, and individuals with special health care needs are addressed by the agency’s research efforts. The research-related activities of the AHRQ are quite varied, but a recent shift emphasizes a more deliberate translation of research evidence into practice. In a process similar to that used by the NIH, investigators are invited to submit research proposals for possible funding through grant announcements. A listing of current areas of the agency’s research interests can be found online at www. ahrq. gov/fund/portfolio. htm. The AHRQ actively promotes EBP, partially through the establishment of 14 EBP centers (EPCs) in the United States and Canada. EPCs conduct research on assigned clinical care topics and generate reports on the effectiveness of health care methodologies. Health care providers may then use the evidence in developing site-speci? c guidelines that direct clinical practice. AHRQ also actively maintains the National Guideline Clearinghouse (www. guidelines. gov), an website that makes available to health care professionals a wide array of clinical practice guidelines that may be considered in health care decision making. Another recent addition to AHRQ’s initiatives is the Healthcare Innovations Exchange (2009b), which provides a public source of information about innovations taking place in health care delivery. Submitted innovations are reviewed for the quality of achieved outcomes, providing evidence as a foundation for decision making by others who may be searching for or considering similar innovations. Although most AHRQ activities are intended to support health care professionals and institutions, the agency supports health care recipients by designing some information speci? cally for dissemination to the lay public (AHRQ, 2009a). 110 UNIT ONE The Development of Nursing Private Foundations Federal funding is available through the NIH and the AHRQ. However, because obtaining money for research is becoming increasingly competitive, voluntary foundations and private and community-based organizations should be investigated as possible funding sources. Many foundations and corporate direct-giving programs are interested in funding health care projects and research. Computer databases and guides to funding are available in local libraries. In addition, grant-seeking enterprises often purchase subscriptions that allow computer access to enhanced listings of funding foundations that include information about the types of projects those foundations typically fund. Though subscriptions are expensive, costs are often balanced by the ef? ciency with which suitable funding prospects are identi? ed. An example of such a service is Prospect Research Online (www. iwave. com). Private foundations, such as the Robert Wood Johnson Foundation (2009a, 2009b) or the W. K. Kellogg Foundation (2009), offer program funding for health-related research. Investigators should be encouraged to pursue funding for small projects through local sources or private foundations until a track record is established in research design and implementation. After several years of experience in the research arena, investigators are more likely to be successful in securing funding through federal sources, such as the NIH. Nursing Organizations Sigma Theta Tau International (STTI), the American Nurses Association (ANA), and the Oncology Nurses Society (ONS), are a few of the nursing organizations that fund research studies. STTI makes research grant awards to increase scienti? c knowledge related to nursing practice. STTI supports creative interdisciplinary research and places importance on identifying â€Å"best practices† and benchmark innovations. Awards are made at the international and local chapter levels. The ANA awards small grants through the American Nurses Foundation. Specialty nursing organizations offer grants to support research related to their specialty. For example, the ONS awards grants that focus on issues related to oncology. To summarize, multiple potential sources of funding are available for research projects. The individual or group wishing to conduct research will need to carefully develop a proposal, search for a possible funding source, and submit the proposal. Libraries and the Internet provide ample information about the many foundations and organizations interested in funding research endeavors. Most research institutions establish of? ces that help in the search and procurement of funding. Thus researchers are supported in their work of knowledge building. COMPONENTS OF THE RESEARCH PROCESS The research process involves conceptualizing a research study, planning and implementing that study, and communicating the ? ndings. The process involves a logical ? ow as each step builds on the previous steps. These steps should be included in published research reports so that the reader has a basis for understanding and critiquing the study (Box 6-2). STUDY DESIGNS Study designs are plans that tell a researcher how data are to be collected, from whom data are to be collected, and how data will be analyzed to answer speci? c research questions. Research studies are classi? ed into two basic methods: quantitative and qualitative, two distinctly different approaches to conducting research. The researcher chooses the method based on the research question and the current level of knowledge about the phenomena and the problem to be studied. Quantitative research is a formal, objective, systematic process in which numeric

Essay --

Describe the role and functions of the PCI security standards council â€Å"The PCI Security Standards Council is an organization created by the major credit card companies in an effort to better protect credit card holder data.† (Rouse, 2012) The council was formed in response to the increase in data security breaches that not only affected customers but also credit card companies cost. With PCI Security Standards Council being a open global forum, The five founding credit card companies – American Express, Discover Financial Services, JCB International, MasterCard Worldwide and Visa Inc. – are responsible for carrying out the organization’s work. Functions of the council include coming up with a framework of specifications, measurements, and support resources to help organizations ensure the safe handling of cardholder information at every step. This is done by managing the Payment Card Industry Security Standard (PCI DSS) and the Payment Application Data Security Standard. Identify/describe key requirements for data security standards The key requirements for the Data Security ...

Use Of Literary Elements :: essays research papers

Use of Literary Elements There are many important elements to The Catcher in the Rye but there are two that stand out from the rest by a great margin. These elements of the novel are the message that the book gives to reader as well as the style of writing that J.D. Salinger uses while writing the book. The messages can be seen clearly and are very important to the book, but they are not an original theme for a book. What does set the ideas in this book apart from other books with the same theme is the writing style that Salinger uses in the book; this writing style is called stream of consciousness writing. Stream of consciousness writing is a type of writing that is not typically used in books because of its well defined limits. These limits are that when using stream of consciousness narration, the story line is required to revolve around one and only one main character if the writing is to be effective. With S. of C. writing it is also required that the author develop the main character extremely well into a very believable person both emotionally and physically through thoughts and actions. To write an effective book in this writing style an author must be exceptionally talented, and thankfully Mr. Salinger is just that. The S. of C. writing style is used effectively with the character of Holden Caulfield in The Catcher in the Rye because the story line Mr. Salinger developed follows Holden specifically as well as the fact that the subject matter of the book is one of an personal nature. The ideas in the book are presented as thoughts of Holden through out the story. These topics include the fakeness of the world, as well as the rebellion against the world that many teenagers have. Holden does not like the phonies in the world and constantly voices his opinion about it as well. The rebellion against the world in not a conscious thing that Holden does but it is apparent in the story line of the book. An example of this rebellion is the constant use of profanity in the book. Salinger makes good use of the constant profanity to show this rebellion but because of HoldenÕs character it is not out of context. Because Holden is upper-middle class and educated he used profanity to exemplify points that he is trying to make, not because he is swearing out of anger.

New Media Technology Essay

Tim Berners-Lee, the creator of the worldwide web, initially intended his invention to be a haven of collaboration where people could share their knowledge (Gauntlett 2009:39). Although the prospect of such public journalism corresponded with democratic and egalitarian principles, journalists took this idea with a pinch of salt. This was almost 20 years ago, before the information highway had, for better or for worse, stretched its limbs across the globe. Today, the new media has redefined both journalism and self expression in conflicting ways that leave an individual wondering at the veracity of digital information. In the last decade, internet has gone through an explosive growth and diversification. No one could have foreseen how the internet would pervade our lives and transform the very notion of being part of a society. It has provided the ultimate freedom of the new age: a single blogger can speak to the entire world, a concept virtually impossible two decades ago. However, with this flourishing and unbound growth, the internet brings a unique set of predicaments and dilemmas. The most profound and relevant of such problems is the age-old clash of a person’s right of self-expression with the hazards of misinformation of the whole society. Whether this deceit comes about due to ignorance or design is irrelevant; in a society that promotes freedom of speech, misinformation is bound to occur on both grounds. While conferring infinite freedom to the common person, this means of self-expression comes with the acrid realization that words from a layman, presented as the predominating views of his community, are not necessarily a blessing. The news on the new media of today is more about gossip and entertainment then first-rate journalism. Since when did journalism begin to cater to the ever-growing need of the populace to be entertained? In an interview to BBC World News America, Ted Koppel, former Nightline presenter, criticized the digital journalist of today for being a mere supplier for consumers (Whitlock 2010). The commercial expansion of new media and ever-growing competition in the free market means that journalists have to write what sells; or rather, gets the most â€Å"hits† on a website. How did we come to a situation where the populace demands not to be informed, but to be perpetually entertained? Discussing news on the television, Daya Kishan Thussu (2007: 9) states: â€Å"There is a concern that too much news is creating an information overload, contributing to a structural erosion of the public sphere in the Habermasian sense, where the viewer, bombarded with visuals, is unable to differentiate between public information and corporate propaganda. † If that is true regarding television news, it most definitely holds water concerning internet news. The gargantuan flow of information, most of which lacks in credibility, is bombarded on any user who wades through the mire of pop up advertisements, banners, and mass e-mailing. Although, these devices are some of the tools used in the race to get more traffic on ones website, the capitalist agenda is far from being the most unfavorable feature of journalism. It is the ubiquitous use of new media, especially by the youth that yields the most detrimental effects. The frivolous writing that is spilt across the new media today may be the first literature some of us encounter, and draw heavily from. However, there have been examples of the internet doing its job where other media have failed. Earlier this year, on January 12th, an earthquake hit the Caribbean island of Haiti. All landlines and mobile connections were suspended. The production team of the news program Sunrise at Sky News, London, was finding it difficult to channel in the first reports from the disaster-struck area. It was to be a young member of their team, Emily Purser, who used Twitter and instant messaging via Google and Skype, to secure the first reports of the incident (Elward 2010). Another, much publicized affair was the use of Twitter by the political opposition in Iran to protest the presidential elections. The protestants took to all sorts of media, but the loudest dissent was voiced, surprisingly, through microblogging. This medium proved to be fast, portable, and most importantly very difficult to contain. Ironically, this very accessibility makes the medium too erratic, unreliable, and mundane to be of any journalistic value (Grossman 2009). An obvious embodiment of the debate between free speech and quality journalism is Wikipedia. This resource epitomizes the â€Å"by the people, for the people† ideology, but this trait alone does not give it any credibility whatsoever, at least not in academic circles. A former editor-in-chief of Encyclopedia Britannica compared Wikipedia to a â€Å"public toilet†, accusing it of delivering information that has no authenticity (Shirky 2006). On the other hand, notions that anything that appears in print media will always be more accurate than digital information are absurd. What Wikipedia envisions is the process through which one can witness the knowledge of its users evolving and perfecting itself through countless revisions (Shirky 2006). The trump card in the argument for Wikipedia comes from a comparison of veracity of data between itself and Britannica; the scientific journal Nature declares them to be of similar accuracy (Giles 2005:900). This collaboration is a sign for those who think people are becoming ever more antisocial and misanthropic, for this is a global effort in creating something for the benefit of all and no monetary gain (Gauntlett 2009:42) . Patricia Wallace, in her book, The Psychology of the Internet writes about how free flow of information can be used to cultivate critical and analytical thinking amongst students who access it (1999:245). Nevertheless, the fact remains that the new media is losing credibility day by day. Although, the global sharing of information and its revision by collaboration is a noble idea, public journalism makes it exceedingly difficult to acquire accurate information; and to accept the new media as a genuine journalistic medium. BIBLIOGRAPHY Gauntlet, David. (2009). Case Study: Wikipedia. Eds. Creeber, G & Martin, R. Digital Cultures. Maidenhead: McGraw-Hill. Thussu, Daya Kishan. (2007). News as Entertainment: The Rise of Global Infotainment. London: SAGE Publications. Wallace, Patricia. (1999). The Psychology of The Internet. Cambridge: Cambridge University Press. Shirky, Clay. Interviewed on Imagine, BBC1, UK (aired 5th December 2006) Giles, Jim. (2005). Internet encyclopedias go head to head, Nature, 438:900. www. nature. com/nature/journal/v438/n7070/full/438900a. html (5th May, 2010) Grossman, Lev. (2009). Iran Protests: Twitter, the Medium of the Movement. Time. http://www. time. com/time/world/article/0,8599,1905125,00. html (5th May, 2010) Whitlock, Scott. (2010). Ted Koppel Slams Undisciplined Internet Journalism. NewsBusters. http://newsbusters. org/blogs/scott-whitlock/2010/04/13/ted-koppel-slams-undisciplined-internet-journalism-longs-good-old-da (5th May, 2010) Elward, David. (2010) Work of a trainee newspaper journalist. (5th May, 2010) http://davidelward. com/2010/03/09/the-digital-revolution-need-not-sound-the-death-knell-for-good-journalism/

Veja Sneakers with a Conscience Essay Example

Veja Sneakers with a Conscience Essay Example Veja Sneakers with a Conscience Paper Veja Sneakers with a Conscience Paper I. Background Morillion and Kopp founded Veja, an eco-sneaker company to serve the ethical fashion industry. This case focuses on the development of sustainable business practices in organic cotton, natural rubber and leather. Veja shows that they can create a product that is both appealing and conscientious. The company grew rapidly due to praise from the media and word of mouth. What leads to their success is the fact that they can integrate sustainable practices into a holistic and ever improving offering, which engages multiple supply chain participants (employees, consumers, suppliers, partners, even artists) in co-devising a value proposition that appeals not just to our sense of fashion, but also to our conscience. II. Challenges and Opportunities Veja encountered challenges due to their small-scale operation at first and the inherent fierce competition from big players in the market. Customers expect ethical products in the first place, so having eco-shoes in Veja’s production line may raise unnecessary costs. Since Veja does not spend on advertising, they may not be able to get the message to the customers that their stores are different from everyone else. In addition, supply for organic materials such as cotton and rubber are limited, which may hinder Veja’s future growth and interrupt their supply chain should adverse weather affect their sources. However, being the few players in the ethical fashion industry, Veja enjoy their first-mover advantage of selecting the finest suppliers. Also, Veja entered the market at the right time because this niche market is growing at a fast rate. Customers are also embracing the green lifestyle and being more aware of ethical fashion. In addition, the corporate culture at Veja allows the employees to be happy, which in turn contribute to the success of the company. III. Veja’s business model vs. conventional model Veja’s business model resembles that of a small business with an entrepreneurial spirit. Since the company started very small, Veja founders were able to control every aspect of their business. The founders knew very little about the fashion industry, aside from the fact that both of them are sneaker addicts. The difference in Veja’s model is that the company learns by doing and making mistakes and willing to take some risks. Veja’s distribution is also different. Instead of having their own store or section for display, the company decided to place their products next to non-ethical brands. This may lead to consumers thinking that their products are just the same as the other name brands. However, this model works for them because Veja’s products are appealing to the mass and the fact that the products were placed in trendy avenues increased their appeals. Veja’s corporate culture is also different from that of conventional model. The company treats the employees well, allowing them lots of freedom and flexibility, paying higher wages than most fashion companies. Veja also encourage work-life balance which show they care for the employees’ happiness. As a result, Veja was able to keep a lot of the original talents. The founders created a supply chain that was based on sustainable relationships. Whereas the fashion industry was accustomed to contracting new parties as soon as a factory could deliver on time or cut costs, Veja tried to improve living conditions and to work cooperatively with supply chain to jointly develop the best product they could imagine. Veja bought raw materials directly from producers. The company paid a fixed price, which, though higher than the market price, was calculated by the farmers. This allowed the farmers to have a higher standard of living. Veja also works solely with cotton and rubber families to produce organic materials. Doing so not only help preserve the Amazon rainforest, but also employ the families in the poverty-stricken area of northern Brazil. Also, Veja continues to research ways to make leather sustainable and works in collaboration with specialist in the field to ensure a sustainable product. This type process improvement mentality is rarely seen in the fashion industry. In contrast to conventional business model, Veja employs two distinct strategies: zero ads and zero stock. Since most of the cost of producing a sneaker was dedicated to marketing, Veja was able to save on cost by having a no advertising policy. Veja benefitted widely from media coverage, blogs, and word of mouth due to their eco-friendly products and ethical business line. Also, most outlets had fewer Veja sneakers than they could sell. Veja did not produce extra, only according to orders placed six months in advance. Doing so ramped up Veja’s popularity because their products are now becoming scarce. Veja’s main business goal was not to make money only by having large volumes, but they want profitability with a conscience.

The Raven Analysis Essay

The Raven Analysis Essay Free Online Research Papers Edgar Allan Poe’s â€Å"The Raven† is a dark reflection on lost love, death, and loss of hope. The poem examines the emotions of a young man who has lost his lover to death and who tries unsuccessfully to distract himself from his sadness through books. Books, however, prove to be of little help, as his nights become a nightmare and his solitude is shattered by a single visitor, the raven. In this poem, Poe uses symbolism, imagery, and tone, as well as a variety of poetic elements to suggest that the sorrow felt about the loss of a love can lead to insanity. Within the poem, Poe divides the characters and imagery into two conflicting aspects of light and dark in which darkness overwhelms the light. Almost everything in the poem reflects one world or the other. â€Å"For the rare and radiant maiden whom the angels named Lenore†. Lenore, who is repeatedly described as â€Å"radiant† epitomizes the world of light along with the angels, emphasize the light. â€Å"And the lamp-light oer him streaming throws his shadow on the floor†. The lamplight the character uses to light his chamber, bring the element of light in the otherwise dark and shadowy chamber. However, The Raven, as well as the dreary December night shows signs of darkness. â€Å"But the raven, sitting lonely on the placid bust, spoke only That one word as if his soul in that one word he did outpour.† The raven is the darkest illustration in the poem and essentially it represents all the pain and grief that is slow pushes him to insanity. These images o f light and darkness go even further to represent love and grief. The man associates images of light in the poem with his love for Lenore and the dark images are associated with the grief of losing Lenore. Told from the third person, Poe also uses symbolism to create a strong melancholy tone. For instance, both midnight and December symbolize an end of something and the hope of something new to happen. Another example is the chamber in which the narrator is placed; this is used to show the loneliness of the man. Along with imagery and symbolism, Poe incorporates many poetic elements to express the characters feeling of sorrow and grief. These include assonance, alliteration, and rhyme. Assonance is the repetition of vowel sounds. For example â€Å"For the rare and radiant maiden, whom the angels name Lenore.† This repeats the vowel sound of â€Å"a†. Poe also used a lot of alliteration. For example, â€Å"Doubting dreaming dreams no mortal ever, dared to dream before†. Observe the repetition of the â€Å"d† sound. Other examples of alliteration can be found in line 64; â€Å"Followed fast and followed faster till his songs one burden bore† Notice the repetition of the â€Å"f† sound at the beginning of the sentence. One last element used in â€Å"The Raven† is a rhyme. A good example of this can be found in the first stanza; dreary, weary, tapping, door, door, more. This is an abcbbb pattern. Each of these sound devices reinforces the meaning by emphasizing important words. Including many elements such as tone, imagery, and symbolism, Poe provided the reader with a better understanding of what exactly is going on in his poem. Without these elements, the reader may have never fully recognized Poe’s theme of death and sadness; loss and loneliness. Research Papers on Analysis Essay of the "The Raven"Albatross and Rimm of the Ancient MarinerLove DivorceTartaros A Place of Ultimate PunishmentThe Damnable Life of FaustThe Broken FamilyThe Gnostic JesusThe Colour PurpleHenderson the Rain KingDefinition of Export QuotasEmmett Till Biography

Oil Drilling in the Artic National Wildlife Refuge essays

Oil Drilling in the Artic National Wildlife Refuge essays In 1870 the first national parks and forests were set aside for wildlife protection and for the extraction of resources. Along with the timber, oil and mining industries, tourism offered economic benefits. But by the 1920s all development was prohibited on these land areas. However external pressure from commercial interests led to the re-opening of these land areas so that the industries could resume operation. In 1964 the Federal Wilderness Act designated wilderness areas as areas where ecosystems are not harmed by man and where man is a visitor and does not remain. Unfortunately it has become quite clear that man has an effect on his entire environment. This is proved in the development and employment of pesticides and other man-made chemicals that travel by ocean currents or seep into ground-water. Moreover, there is still pressure to expand the commercial use of national forests and parks and strip wilderness areas of their protection from this commercial use to exploit their r esources. In 1960, the Artic National Wildlife Refuge (ANWR) was classified as a wildlife preserve. However in 1980 the ANWR was evaluated for its potential economic gain by drilling oil. In 1987 the Department of the Interior proposed that the coastal plain be open for drilling but President Bill Clinton vetoed Congresss approval. In 2001 California experienced many electrical blackouts. President George W. Bush declared that California was experiencing an energy crisis and that opening the ANWR was imperative to maintain national energy security. The National Energy Security Act of 2001 was promptly enacted and debated strongly ever since. Overall, the debate over the protection of wildlife areas is primarily focused around economic arguments. The first argument suggests that the economic benefits from the exploitation of natural resources are so great that it should be permitted. The alternative side recognizes only a short-ter...

Juvenile Offenders Term Paper Example | Topics and Well Written Essays - 2000 words

Juvenile Offenders - Term Paper Example Third, majority of the juvenile offenders have a traumatic history which not only questions their mental health but also the efficiency of social institutions such as schools, high schools, hospitals, family and others to ensure proper development of children. Fourth, European Convention of Human Rights, Universal Declaration of Human Rights, United Nations Convention on Rights of the Child and other international charters and conventions clearly state about the right of every person to live and the fact that children can not receive capital punishments. Fifth, the public opinion is supports the stance of this paper. Sixth, capital punishment evades the chance of any individual to prove him or her innocent in future in light of any new developments or evidence. Introduction This paper is an attempt to explore the controversial, serious, and debatable issue about juvenile offenders. The paper discusses the question of legal execution of juvenile offenders who are less than the age of 18 years and have committed a murder. Statement of Problem The paper will take the stance that "Juvenile offenders who commit murder under the age of 18 should not be legally executed". ... First, since the past few years, this issue has been of great attention and debate in the public and expert circles. Second, in light of my personal stance on the topic, I believe that by legal execution of juvenile offenders, the law enforcement agencies are not following but breaking the law and contributing to a crime and it is our responsibility to play our part to stop it. Third, children are the future of any nation and if they are committing such actions then this is a wake up call for all authorities and with the help of this paper, I put emphasis on the fact that it is time for them to sit down and reexamine the entire system and the root cause of the same. Discussion One of most important arguments in opposition of juveniles facing legal execution is the fact that studies have shown that children under the ages of 18 are still in their developmental stages. During this age, juveniles are still immature and they fail to understand the full weight and consequences of their de cision (Siegel & Welsh, 2008). Furthermore, children are more vulnerable to peer-pressure and are more likely to engage in risky behaviors. Since they are developmentally different from adults, they fail to control their temptations and impulses, which make it morally incorrect to treat them as adults or blame them for their actions in the same way as adults (Hesse, Lawrence & Hesse, 2009). That is also the reason why 18 years is the minimum age for every big step in life. There are many countries in the world, which do not allow marriage before the age of 18; in fact, some countries and states extend the same to the limit to the age of 21 (Boesky & American Correctional Association, 2002). Moreover, 18 years is also the minimum age for voting, entering into a

Britain and the empire Essay Example | Topics and Well Written Essays - 1000 words

Britain and the empire - Essay Example Thompson believes that the concept of the new clock time, came into existence because of capitalistic interests, replaced the earlier perception of time3. These earlier perceptions of time, emanated from the collective wisdom of mankind. These earlier views regarding time were imposed by religious and social authorities, before the emergence of the industrial revolution. This paper analyzes the ideas of Thompson regarding how time was perceived by the traditional society, and how it changed during the industrial revolution. This is in the late 1700s. Furthermore, this paper analyzes who had the ability of telling time, and how the changes and use of time affected the rural laborers during the 1700s, and what is meant by â€Å"Saint Monday†. This paper further analyzes how the discipline of time regulation related to the wages and experiences of the workers during the 18th century. It further analyzes the context of idleness, in the view of Thompson. This paper also contains the independent ideas and insights of the essay by Thompson. Thompson denotes that during the pre-industrial societies, people had different views and believes about time4. This believes and views were imposed by social and religious authorities, and based on collective wisdom of members of a society. These societies viewed time, based on their commercial, social, and religious activities. For example, in societies that practiced hunting, agriculture, and other human interaction activities with the natural world, time discipline was governed by biological, as well as astronomical factors. People knew specific seasons, or times through observations. The Islamic lunar calendar is an example in which people identified time and seasons through religious means. This calendar was developed by the nomadic Arabs, who lived in the deserts. The lunar calendar does not reflect any seasons, because it was not convenient for these Arabs. However, with the arrival of

Love and time Essay Example | Topics and Well Written Essays - 1000 words

Love and time - Essay Example Likewise, the second which will be analyzed is Andrew Marvell’s â€Å"To His Coy Mistress†. Even though these two points were written in roughly the same timeframe, the key differential which will be analyzed is with regards to the way in which the respective authors understand love and somewhat of an asymmetrical manner. As will be discussed within the preceding analysis, John Donne’s point focuses upon love existing outside of the con strains of time whereas Andrew Marvell’s point focuses upon the immediacy, urgency, and physical necessity of love existing within the very moment. Through an analysis and discussion of these facts, it is the hope of this author that the reader will gain a more informed understanding with respect to the way in which love was understood in different ways by different authors; even within the same era. Firstly, with regards to Andrew Marvell’s poem, â€Å"To His Coy Mistress†, the reader can quickly come to unde rstand that the approach that this particular poet utilizes is one that places a profound level of emphasis and importance upon what can only be described as a â€Å"carpe diem† approach to life. Within this particular approach, the poet encourages the Mistress to accept his sexual advances and to discontinue her coy behavior. However, by much the same token, rather than merely seeking to break down the walls of seeming rejection that the woman places as an impediment for the subject to overcome, a further focus is placed upon insisting that the love and devotion that he shares for her is not as fleeting and short-lived as a mere sexual fascination. Instead, the author focuses a great deal of energy on examining the fact that even though the time to act is now and an urgency, tension, and immediacy defines the love and passion that the subject has for the Mistress, a deeper and more profound realization of what defines love and the eternity of passion and interest that the su bject could direct for this Mistress if only she opened her heart and her body to the subject is reflected in a variety of different ways. For instance, after the exhortation to stop dismissing the advances of the suitor, Marvell references the fact that in so doing the woman would be able to experience love as she had never before seen it. Ultimately, what is presented to the reader is an argument for the immediacy, passion, and necessity to experience love in the moment. However, due to the fact that a woman would likely find the emotion of immediacy and the need to seize the day as alarming and definitive of a passing craze or crush, the poetry goes to great lengths to prove that the nature of the emotions that are being defined are not short-lived but will instead last for far longer than life itself is able to exist. By means of contrast, John Donne spends almost the entirety of his point in discussing the fact that love does not require a public profession and easily understoo d emotions. Ultimately, the key differential between these two poets is with regards the fact that John Donne’s poem focuses upon the fact that time in and of itself is unimportant to love and love exists beyond and outside of this temporal concept/construct (D'addario 421). Completely contrary to Andrew Marvell’

Macroeconomic Outlook for Oil Prices Owing to Unrest in the Middle Essay

Macroeconomic Outlook for Oil Prices Owing to Unrest in the Middle East - Essay Example So if for example, we choose to use oil as source of energy instead of thermal or wind, we are trading off thermal or wind for oil as source of energy. Economics is also about cost and benefit analysis. This is because when we try to solve our economic problems and make choices, we look at it through economic perspective by comparing the costs and benefits of our choices. By using oil for energy source means that its costs and benefits are favorable over the other alternatives, thermal and wind sources. B. Market, Demand and Supply Just like any good in the market, oil demand and supply are affected by several factors in the market. Any change in its demand and supply will affect its price and its impact will be felt by the whole economy as well. 1. Market Market is simply a mechanism or arrangement which brings buyers or demanders and sellers or suppliers of a good or service into contact with one another (McConnell and Brue 2002, 49). In this article, we will be analyzing the oil m arket, meaning the mechanism or arrangement where the exchange happens between the buyers and sellers of oil. Buyers or demanders are the ones who are willing and able to exchange their money for oil. On the other hand, sellers or suppliers are those who are willing and able to exchange their product which is oil for money. 2.Demand The report cited that the EIA forecasted demand for oil is usually in the middle of OPEC and EIA demand outlooks. Demand refers to the quantities of a specific good or service that people are willing to purchase at any given price during a specified time period, given other things being constant (Miller 2004, 99). When taken singly, it is referred to as the... This essay presents a comprehensive analysis of the factors, determining the oil price and its volumes of deliveries against the background of worsening political situation in the Middle East. Market is simply a mechanism or arrangement which brings buyers or demanders and sellers or suppliers of a good or service into contact with one another. Demand refers to the quantities of a specific good or service that people are willing to purchase at any given price during a specified time period, given other things being constant. Supply is the amount of a particular good or service a seller or supplier is willing and able to produce and make available for sale at specific price and time. The total of all the supply available in a market will be the market supply Prices affect market demand and supply but there are other factors present in the market that can cause changes and can determine market demand and supply. The surplus in oil stocks was forecasted because the demand is at slower rate than the production. So, if the oil suppliers will continue producing oil at the same rate as before, they will be producing more than what the oil demanders are willing to buy from them. This situation will result to a surplus of oil in the market. To at least decrease the amount of surplus and bring the production near to equilibrium, OPEC members agreed to cut their supply by setting output quotas. The expectations about the future economic condition cause consumers to cut their spendings.

Globalisation and Tourism and the impact on local and indigenous Essay

Globalisation and Tourism and the impact on local and indigenous cultures - Essay Example It is about establishing interconnected relations throughout the world. Through globalization one can eliminate the barriers that persist within nations, develop healthy trade, bridges communication errors and shares resources. One of the disadvantages of globalization is that it has increased crime level interstate. Los Angeles is one of the most densely polluted countries of the world. Pollution has literally damaged the entire city in such a way that its impact is very obvious. Tourism is an essential part of Los Angeles economy. Los Angeles is one of those countries that are a major tourist attraction, Los Angeles has the honour of housing the home of all legendary actors that is Hollywood. From amazing shopping malls to Hollywood and an amazing blend of various restaurants, Los Angeles offers everything that a tourist wants during vacations. While travelling the quality and the atmosphere of the environment go hand in hand. The environment is made up of natural as well as manmad e things which together build up the tourism in a state. The relation between tourism and environment tends to get very tangling at times. The effects of tourism are very controversial. At times they can be helpful in generating revenue for the state resulting in a fruitful economy and on the contrary it can damage and dent the city's environmental condition resulting in a disaster which can damage countries natural resources. Tourism leads to the development of the place with the construction of roads, parks, malls, resorts, restaurants, hotel, golf courses, airports etc. which eventually build up the infrastructure of a place. "The notion of a tourism system is extremely important when we start to consider the notion of impacts. If we are to evaluate the effects of tourism trips, we need not only to examine where in the system immediate impacts occur, but also to consider if there are system-wide effects that contribute to change in the broader environment. In the case of maritime ship emissions, for example, nitrogen oxide( NOx) have both local and global effects on atmospheric pollution. In the Los Angeles – Long Beach area of California, which is both the United States busiest port and the country's most polluted area, oceangoing vessels are among the largest source of NOx, emitting more NOx than all power plants and refineries in the region's air basin combined. This is significant because as well as being a green house gas (GHG) that contribute to global warming and climate change. NOx reacts with other volatile organic compounds in the atmosphere to produce ozone/smog. Particulates from marine vessels also create significant cancer risks, with an estimated more than 700 premature deaths caused in the Los Angeles area annually by these emissions as of 2008. Because of their often localized nature, the effects of NOx are not just felt in ports, but also along shipping transit routes. For example, Santa Barbara county in California, which has no co mmercial port, estimates by 2020, 67 percent of its NOx inventory will come from shipping traffic transiting the Californian coast." (Scott, 45). This particularly deals with the marine emission that has damaged Los Angeles brutally. This text

Macroeconomic Outlook for Oil Prices Owing to Unrest in the Middle Essay

Macroeconomic Outlook for Oil Prices Owing to Unrest in the Middle East - Essay Example So if for example, we choose to use oil as source of energy instead of thermal or wind, we are trading off thermal or wind for oil as source of energy. Economics is also about cost and benefit analysis. This is because when we try to solve our economic problems and make choices, we look at it through economic perspective by comparing the costs and benefits of our choices. By using oil for energy source means that its costs and benefits are favorable over the other alternatives, thermal and wind sources. B. Market, Demand and Supply Just like any good in the market, oil demand and supply are affected by several factors in the market. Any change in its demand and supply will affect its price and its impact will be felt by the whole economy as well. 1. Market Market is simply a mechanism or arrangement which brings buyers or demanders and sellers or suppliers of a good or service into contact with one another (McConnell and Brue 2002, 49). In this article, we will be analyzing the oil m arket, meaning the mechanism or arrangement where the exchange happens between the buyers and sellers of oil. Buyers or demanders are the ones who are willing and able to exchange their money for oil. On the other hand, sellers or suppliers are those who are willing and able to exchange their product which is oil for money. 2.Demand The report cited that the EIA forecasted demand for oil is usually in the middle of OPEC and EIA demand outlooks. Demand refers to the quantities of a specific good or service that people are willing to purchase at any given price during a specified time period, given other things being constant (Miller 2004, 99). When taken singly, it is referred to as the... This essay presents a comprehensive analysis of the factors, determining the oil price and its volumes of deliveries against the background of worsening political situation in the Middle East. Market is simply a mechanism or arrangement which brings buyers or demanders and sellers or suppliers of a good or service into contact with one another. Demand refers to the quantities of a specific good or service that people are willing to purchase at any given price during a specified time period, given other things being constant. Supply is the amount of a particular good or service a seller or supplier is willing and able to produce and make available for sale at specific price and time. The total of all the supply available in a market will be the market supply Prices affect market demand and supply but there are other factors present in the market that can cause changes and can determine market demand and supply. The surplus in oil stocks was forecasted because the demand is at slower rate than the production. So, if the oil suppliers will continue producing oil at the same rate as before, they will be producing more than what the oil demanders are willing to buy from them. This situation will result to a surplus of oil in the market. To at least decrease the amount of surplus and bring the production near to equilibrium, OPEC members agreed to cut their supply by setting output quotas. The expectations about the future economic condition cause consumers to cut their spendings.

Perfect Competition Essay Example | Topics and Well Written Essays - 1750 words

Perfect Competition - Essay Example Perfect Competition The model of perfect competition is based upon four assumptions. Firstly the firms are price takers. There are so many firms in the market that and single firm does not produce enough of the whole to be able to influence the market price. Therefore, they are considered as price takers where the price has already been determined at the market forces of demand and supply. There are no barriers of entry or exit for the firms. There are no stopping firms who wish to enter or leave the market. The existing firms have no role in this process. All firms are producing homogenous products. This means that the products of all firms are identical and as a result there can be no marketing in terms of names of brands. All the producers and consumers have perfect information regarding the prices of the products. Very few firms or industries come close to this model in the real world. We may see such conditions temporarily in the agricultural industry but, these do not exist in the long run. In per fect competition as stated in the assumptions above it is assumed that there are many small firms and that they cannot do anything to influence the market price. Therefore, they are considered as price takers where the price has already been determined at the market forces of demand and supply. There are no barriers of entry or exit for the firms. There are no stopping firms who wish to enter or leave the market. The existing firms have no role in this process. All firms are producing homogenous products. This means that the products of all firms are identical and as a result there can be no marketing in terms of names of brands. All the producers and consumers have perfect information regarding the prices of the products. (Sloman,2006) Very few firms or industries come close to this model in the real world. We may see such conditions temporarily in the agricultural industry but, these do not exist in the long run. In perfect competition as stated in the assumptions above it is assu med that there are many small firms and that they cannot do anything to influence the market price. The firm’s contribution to the industry and market is so small that even if it changes its output it will have no effect on the market price of the product. Thus, the firm can produce any quantity hoping to sell all of it at market price. Considering this it is derived that the demand curve is perfectly elastic and thereby, marginal revenue earned for each additional output sold is same throughout. Therefore, the marginal revenue is equal to average revenue (Bamford et al 2002.). Thus, considering that the individual firms do not affect the market price the only real decision which they have to make is the level of output to be produced. This decision can be taken by taking into account the costs of production. Considering the basic objective of the firm is to maximize profits it will produce at the point where marginal costs equals marginal revenue (MC=MR). (Bamford et al. 200 2) The first thing which needs to be understood is the difference between the short run and the long run. During the short run the number of firms in the industry is fixed. This means that no new firms will be entering the market in the short run. The existing firms will have the chance to earn abnormal profits in the short run. However, in the long run there will be other firms entering the market. Firms will enter the market if there will be signs of abnormal profits. On the other hand, if there are losses some firms may also leave the industry. (Sloman,2006) The total revenue to be earned by the firm will be equal to the price multiplied by the quantity sold. If the total cost of producing this specified number of units is lesser than the total revenue then it can be said that the firm is making abnormal profits. This will actually be an incentive for the firm to keep producing at the current rate. However, if total revenue equals total coast (TR=TC), then the firm is barely maki ng it to the breakeven point. It is this point where the firm is earning normal profits. On the other hand, it is plausibility that the total cost is greater than the total revenue. If the costs are greater, the firm may exit the industry altogether. This may not be the case at all times. If the total revenue is greater than

International Students Essay Example for Free

International Students Essay Attention getter- â€Å"Did you have a lion in your backyard when you were growing up?† â€Å"Did you have to hunt for your food?† Reveal Topic- These were the questions asked by my classmates when I first moved to the United States. Often times, international students are asked bizarre questions about their culture. Frequently, international students are asked what their names mean and although most may know, some don’t have the slightest idea. My name, Taiwo, means first of the twins to be born and the first to taste the world. From the audience survey I received back, only 2 out of 16 people that took the survey knew the meaning of their name. Most questions asked of international students can be humorous but some are very offensive. Credibility Statement- I moved to the United States when I was 12 years old, and my biggest problem was readjusting to the weather, which by the way I’m still not adjusted to. In Nigeria, my home country, there are only two seasons which are the wet and the dry season. Although I am not an international student, I can relate because I had to go through so many changes and at one point it was unbearable. Each year, Johnson County Community College is home to international students from more than one hundred countries with their own cultures, skills, and struggles. Preview of main points- Today, I am going to inform you about international students struggle with challenges like cultural and social adjustment. Connective- First, I would like to explain I. International student’s struggles with cultural adjustments. A. According to Gregory Trivonovitch, there are four transitional stages: a honeymoon, hostility, integration/acceptance, and finally, the home stage. 1. The honeymoon stage is described as the stage full of joy and excitement because most international students that are just arriving are captivated with everything new. They  a excited to start studying at a United States university. The second stage is hostility that â€Å"is characterized by frustration, anger, anxiety, judgementalism, fear, and sometimes depression† (Claremont). The third stage  is integration and acceptance, meaning when international students start to feel comfortable and relaxed in their new environment. At this stage they can join different clubs like the international club. The international club at Johnson County Community college â€Å"brings together students from America and around the globe for educational and social activities† (Johnson County Newspaper). The last stage is the home stage. This final stage is the â€Å"feel at home† stage that allows the students to absorb both their culture and the American culture. 2. Students go through these stages because they feel that they have lost but at the same time gained their identity. B. The anxiety and stress of being separated from their families, relatives, and their friends in their native countries can be overwhelming for them. 1. Leaving a culture and surroundings that one is very familiar with while transitioning to a new one can be difficult. 2. For instance, my friend john, an international student, said he asked one of his friend to â€Å"hook up†, meaning he wanted to hang out, but his friend taught he meant to â€Å"hook up† â€Å"hook up† as in sexually. John also mention how difficult it was for him to adjust to this new lifestyle and is still learning how to. Connective- Now that I have informed you about international students struggle with cultural adjustment and along with it explaining the four stages of cultural shock, II. I am going to explain international students’ struggles with social adjustment. A. International students usually stay in the United States for a short period of time or depending on how long they study for. They face sets of challenges such as interacting with others and making new friends. B. â€Å"International students may also experience a loss of social status and self-respect because their social standing in their home country may not be recognized in the U.S.† (Eunyoung). 1. Even though their suffering might be too much there are ways to manage. As mentioned earlier, the Johnson County Community College International club is a great way to network. a. The club â€Å"is an organization that works to increase international understanding and friendship† (JCCC brochure). b. This club as many goals in mind like â€Å"support for new students, social activities that increase awareness about American culture, fundraising activities to support scholarships for international students† and more (JCCC brochure). 2. Fear of belonging and coping with it. Conclusion- In closing we have learned the struggle international students face with challenges like cultural and social adjustment challenges. International students badly need to be given full initial and ongoing explanations of what is expected of them, how the system works, and where to get help. Being in a country you’re not familiar helps you learn. If you go to a foreign country you are not familiar with, these tips will be very useful in adjusting without any complications. Bibliography Stages of Cultural Adjustment. CGU Writing Center. Claremont Graduate University, n.d. Web. http://www.cgu.edu/pages/945.asp. Hurtado, David. Students Clubs Aim to Increase Involvement. The Campus Ledger 21 Sept. 2012: 6. Print. Johnson County Community College International Club. Johnson County: n.p., 2012. Print. Eunyoung, Kim. An Alternative Theoretical Model: Examining Psychosocial Identity Development of International Students in the United States. Rep. Project Innovation (Alabama), n.d. Web.

An operational amplifier

An operational amplifier Introduction: Anoperational amplifier, which is often called anop-amp, is aDC-coupledhigh-gainelectronic voltageamplifierwith a differential input and, usually, a single-ended output.An op-amp produces an output voltage that is typically millions of times larger than the voltagedifferencebetween its input terminals. Typically uses of the operational amplifier are to provide voltage amplitude changes (amplitude and polarity), oscillators, filter circuits, and many types of instrumentation circuits. An op-amp contains a number of differential amplifier stages to achieve a very high voltage gain. Typically the op-amps very large gain is controlled bynegative feedback, which largely determines the magnitude of its output voltage gain in amplifier applications, or thetransfer functionrequired. Without negative feedback, and possibly withpositive feedbackforregeneration, an op-amp essentially acts as acomparator. High inputimpedanceat the input terminals and low output impedance at the output terminals (ideally zero) are important typical characteristics. Op-amps are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices. Many standard IC op-amps cost only a few cents in moderate production volume; however some integrated or hybrid operational amplifiers with special performance specifications may cost over $100 US in small quantities. Op-amps sometimes come in the form of macroscopic components, or asintegrated circuitcells; patterns that can be reprinted several times on one chip as part of a more complex device. The op-amp is one type ofdifferential amplifier. Other types of differential amplifier include thefully differential amplifier(similar to the op-amp, but with two outputs), theinstrumentation amplifier(usually built from three op-amps), theisolation amplifier(similar to the instrumentation amplifier, but with tolerance to common-mode voltages that would destroy an ordinary op-amp), andnegative feedback amplifier(usually built from one or more op-amps and a resistive feedback network). An Amplifier is made of: A Gain Block (ideally possessing infinite gain) Feedback A Network that sets the amount of feedback (e.g. resistors) The circuit symbol for an op-amp is shown to the right, where: The power supply pins (V_{text{S}!+}andV_{text{S}!-}) can be labelled in different ways). Despite different labelling, the function remains the same to provide additional power for amplification of signal. Often these pins are left out of the diagram for clarity, and the power configuration is described or assumed from the circuit. Op amps are versatile ICs that can perform a variety of mathematical functions. For this reason, they are the building blocks of many signal processing circuits. They have almost infinite gain, high input impedance, and low output impedance. Because of this, there is no current drawn at either input, and the voltage at both inputs must be equal (they are often drawn with a short connecting them) Op amps have two inputs, an inverting (-) and non inverting (+). A positive voltage source and negative voltage source or ground are connected directly to the op amp, although these are rarely shown on circuit diagrams. There is a single output, which is almost always connected to the inverting input with a feedback loop. Ideal Op Amps: There are three rules for analyzing op amp circuits. In addition to KVL and KCL, any op amp circuit should be solvable with these rules. Infinite input impedance. No current is drawn so: Infinite gain. This means that the input voltages must be equal. Zero output impedance. This means that output voltage does not depend on the output current. Real Op Amps: Ideal op amps are modelled with infinite gain and infinite impedance. While real op amps have high gain and low impedance, they are not infinite. This limiting factor can affect the performance of the circuit, so it should be considered. Another limitation of real op amps is voltage gain. Instead of being infinite, the maximum output voltage is about 1.4 V lower than the supply voltage (this is due to diode drops in the op amp). Ideal behaviour is not an accurate modelling technique when square waves are used. For this type of input, the voltage changes infinitely fast as it jumps from the high to the low parts of the wave. Op amps cant change instantaneously, there is a slight slope produced in the output. This can be measured by the slew rate (with is the change in voltage over the change in time). Rise time is another parameter used to calculate how quickly an op amp can adjust. The amount of time it takes the voltage to change from 10% to 90% of the desired value is the rise time. For application with square wave input, these two factors can affect the response of your circuit. Connecting an Op Amp: Op amps with Dual in Line Packages should be connected to a breadboard as shown here. The notch is at the top of the op-amp, with pins counted counter clockwise from the upper left corner. Operation: The amplifiers differential inputs consist of V_{!+}input and aV_{!-}input, and ideally the op-amp amplifies only the difference in voltage between the two, which is called thedifferential input voltage. The output voltage of the op-amp is given by the equation, WhereV_{!+}the voltage at the non-inverting terminal is,V_{!-}is the voltage at the inverting terminal andGopen-loopis theopen-loopgain of the amplifier. (The term open-loop refers to the absence of a feedback loop from the output to the input.) Op-amp with inverting input grounded through a resistor; input at the non-inverting input, and no feedback With no negative feedback, the op-amp acts as a switch. The inverting input is held at ground (0 V) by the resistor, so if the Vinapplied to the non-inverting input is positive, the output will be maximum positive, and if Vinis negative, the output will be maximum negative. Since there is no feedback from the output to either input, this is anopen loopcircuit. The circuits gain is just the Gopen-loopof the op-amp. Standard two-resistor non-inverting amplifier circuit The magnitude ofGopen-loopis typically very large-seldom less than a million-and therefore even a quite small difference betweenV_{!+}andV_{!-}(a few microvolts or less) will result in amplifier saturation, where the output voltage goes to either the extreme maximum or minimum end of its range, which is set approximately by the power supply voltages.Finleys lawstates that When the inverting and non-inverting inputs of an op-amp are not equal, its output is in saturation. Additionally, the precise magnitude ofGopen-loopis not well controlled by the manufacturing process, and so it is impractical to use an operational amplifier as a stand-alonedifferential amplifier. If linear operation is desired,negative feedbackmust be used, usually achieved by applying a portion of the output voltage to the inverting input. The feedback enables the output of the amplifier to keep the inputs at or near the same voltage so that saturation does not occur. Another benefit is that if much negative feedb ack is used, the circuits overall gain and other parameters become determined more by the feedback network than by the op-amp itself. If the feedback network is made of components with relatively constant, predictable, values such as resistors, capacitors and inductors, the unpredictability and inconstancy of the op-amps parameters (typical of semiconductor devices) do not seriously affect the circuits performance. If no negative feedback is used, the op-amp functions as a switch or comparator. Positive feedback may be used to introducehysteresisor oscillation. Returning to a consideration of linear (negative feedback) operation, the high open-loop gain and low input leakage current of the op-amp imply two golden rules that are highly useful in analysing linear op-amp circuits. Golden rules of op-amp negative feedback Ifthere is negative feedback andifthe output is not saturated, both inputs are at the same voltage; no current flows in or out of either input. These rules are true of the ideal op-amp and for practical purposes are true of real op-amps unless very high-speed or high-precision performance is being contemplated (in which case account must be taken of things such as input capacitance, input bias currents and voltages, finite speed, and otherop-amp imperfections, discussed in a later section.) As a consequence of the first rule, theinput impedanceof the two inputs will be nearly infinite. That is, even if the open-loop impedance between the two inputs is low, the closed-loop input impedance will be high because the inputs will be held at nearly the same voltage. This impedance is considered as infinite for an ideal opamp and is about onemegaohmin practice. Ideal and real op-amps: An equivalent circuit of an operational amplifier that models some resistive non-ideal parameters. An ideal op-amp is usually considered to have the following properties, and they are considered to hold for all input voltages: Infiniteopen-loop gain(when doing theoretical analysis, alimitmay be taken as open loop gainGgoes to infinity) Infinite voltage range available at the output (vout) (in practice the voltages available from the output are limited by the supply voltagesV_{text{S}!+}andV_{text{S}!-}) Infinitebandwidth(i.e., the frequency magnitude response is considered to be flat everywhere with zerophase shift). Infiniteinput impedance(so, in the diagram,R_{text{in}} = infty, and zero current flows fromv_{!+}tov_{!-}) Zero input current (i.e., there is assumed to be noleakageorbiascurrent into the device) Zeroinput offset voltage(i.e., when the input terminals are shorted so thatv_{!+}=v_{!-}, the output is avirtual groundor vout= 0). Infiniteslew rate(i.e., the rate of change of the output voltage is unbounded) and power bandwidth (full output voltage and current available at all frequencies). Zerooutput impedance(i.e.,Rout= 0, so that output voltage does not vary with output current) Zeronoise InfiniteCommon-mode rejection ratio(CMRR) InfinitePower supply rejection ratiofor both power supply rails. In practice, none of these ideals can be realized, and various shortcomings and compromises have to be accepted. Depending on the parameters of interest, a real op-amp may be modelled to take account of some of the non-infinite or non-zero parameters using equivalent resistors and capacitors in the op-amp model. The designer can then include the effects of these undesirable, but real, effects into the overall performance of the final circuit. Some parameters may turn out to havenegligibleeffect on the final design while others represent actual limitations of the final performance that must be evaluated. History: 1941: First (vacuum tube) op-amp An op-amp, defined as a general-purpose, DC-coupled, high gain, inverting feedbackamplifier, is first found in US Patent 2,401,779 Summing Amplifier filed by Karl D. Swartzel Jr. of Bell labs in 1941. This design used threevacuum tubesto achieve a gain of 90dB and operated on voltage rails of  ±350V. It had a single inverting input rather than differential inverting and non-inverting inputs, as are common in todays op-amps. ThroughoutWorld War II, Swartzels design proved its value by being liberally used in the M9artillery directordesigned at Bell Labs. This artillery director worked with the SCR584radarsystem to achieve extraordinary hit rates (near 90%) that would not have been possible otherwise. 1947: First op-amp with an explicit non-inverting input In 1947, the operational amplifier was first formally defined and named in a paper by Professor John R. Ragazzini of Columbia University. In this same paper a footnote mentioned an op-amp design by a student that would turn out to be quite significant. This op-amp, designed by Loebe Julie, was superior in a variety of ways. It had two major innovations. Its input stage used a long-tailedtriode pair with loads matched to reducedriftin the output and, far more importantly, it was the first op-amp design to have two inputs (one inverting, the other non-inverting). The differential input made a whole range of new functionality possible, but it would not be used for a long time due to the rise of the chopper-stabilized amplifier. 1949: First chopper-stabilized op-amp In 1949, Edwin A. Goldberg designed achopper-stabilized op-amp.This set-up uses a normal op-amp with an additionalACamplifier that goes alongside the op-amp. The chopper gets an AC signal fromDCby switching between the DC voltage and ground at a fast rate (60Hz or 400Hz). This signal is then amplified, rectified, filtered and fed into the op-amps non-inverting input. This vastly improved the gain of the op-amp while significantly reducing the output drift and DC offset. Unfortunately, any design that used a chopper couldnt use their non-inverting input for any other purpose. Nevertheless, the much improved characteristics of the chopper-stabilized op-amp made it the dominant way to use op-amps. Techniques that used the non-inverting input regularly would not be very popular until the 1960s when op-ampICsstarted to show up in the field. In 1953, vacuum tube op-amps became commercially available with the release of the model K2-W from George A. Philbrick Researches, Incorporated. The designation on the devices shown, GAP/R, is a contraction for the complete company name. Two nine-pin 12AX7 vacuum tubes were mounted in an octal package and had a model K2-P chopper add-on available that would effectively use up the non-inverting input. This op-amp was based on a descendant of Loebe Julies 1947 design and, along with its successors, would start the widespread use of op-amps in industry. 1961: First discrete IC op-amps With the birth of thetransistorin 1947, and the silicon transistor in 1954, the concept of ICs became a reality. The introduction of theplanar processin 1959 made transistors and ICs stable enough to be commercially useful. By 1961, solid-state, discrete op-amps were being produced. These op-amps were effectively small circuit boards with packages such as edge-connectors. They usually had hand-selected resistors in order to improve things such as voltage offset and drift. The P45 (1961) had a gain of 94dB and ran on  ±15V rails. It was intended to deal with signals in the range of  ±10V. 1962: First op-amps in potted modules By 1962, several companies were producing modular potted packages that could be plugged intoprinted circuit boards. These packages were crucially important as they made the operational amplifier into a singleblack boxwhich could be easily treated as a component in a larger circuit. 1963: First monolithic IC op-amp In 1963, the first monolithic IC op-amp, the  µA702 designed byBob Widlarat Fairchild Semiconductor, was released. MonolithicICsconsist of a single chip as opposed to a chip and discrete parts (a discrete IC) or multiple chips bonded and connected on a circuit board (a hybrid IC). Almost all modern op-amps are monolithic ICs; however, this first IC did not meet with much success. Issues such as an uneven supply voltage, low gain and a small dynamic range held off the dominance of monolithic op-amps until 1965 when the  µA709 was released. 1966: First varactor bridge op-amps Since the 741, there have been many different directions taken in op-amp design.Varactorbridge op-amps started to be produced in the late 1960s; they were designed to have extremely small input current and are still amongst the best op-amps available in terms of common-mode rejection with the ability to correctly deal with hundreds of volts at their inputs. 1968: Release of the  µA741 The popularity of monolithic op-amps was further improved upon the release of the LM101 in 1967, which solved a variety of issues, and the subsequent release of the  µA741 in 1968. The  µA741 was extremely similar to the LM101 except that Fairchilds facilities allowed them to include a 30pF compensation capacitor inside the chip instead of requiring external compensation. This simple difference has made the 741thecanonical op-amp and many modern amps base their pin out on the 741s.The  µA741 is still in production, and has become ubiquitous in electronics-many manufacturers produce a version of this classic chip, recognizable by part numbers containing741. 1970: First high-speed, low-input current FET design In the 1970s high speed, low-input current designs started to be made by usingFETs. These would be largely replaced by op-amps made withMOSFETsin the 1980s. During the 1970s single sided supply op-amps also became available. 1972: Single sided supply op-amps being produced A single sided supply op-amp is one where the input and output voltages can be as low as the negative power supply voltage instead of needing to be at least two volts above it. The result is that it can operate in many applications with the negative supply pin on the op-amp being connected to the signal ground, thus eliminating the need for a separate negative power supply. The LM324 (released in 1972) was one such op-amp that came in a quad package (four separate op-amps in one package) and became an industry standard. In addition to packaging multiple op-amps in a single package, the 1970s also saw the birth of op-amps in hybrid packages. These op-amps were generally improved versions of existing monolithic op-amps. As the properties of monolithic op-amps improved, the more complex hybrid ICs were quickly relegated to systems that are required to have extremely long service lives or other specialty systems. Recent trends Recently supply voltages in analog circuits have decreased (as they have in digital logic) and low-voltage op-amps have been introduced reflecting this. Supplies of  ±5V and increasingly 5V are common. To maximize the signal range modern op-amps commonly have rail-to-rail inputs (the input signals can range from the lowest supply voltage to the highest) and sometimes rail-to-rail outputs. A very typical commercial IC op amp circuit is the 741. This IC has been available for many years, and a number of variations have been developed to help minimize the errors inherent in its construction and operation. Nevertheless, the analysis we will perform here using the 741 will apply to any other IC op amp, if you take into account the actual parameters of the device you are actually using. Therefore, we will use the 741 as our example IC op amp. A differential amplifier connected as an op amp. To the right is a circuit using the 741 op amp IC, with the input and feedback resistors that are required for this circuit to operate properly in an analog computer. Note that there are actually two inputs to the amplifier, designated + and - in the figure. This is because the 741, like all IC op amps of this type, is in fact a differential amplifier. Thus, the output voltage is determined by thedifferencebetween the two input voltages. The +, or non-inverting input, is grounded through a resistor as shown. Thus, its input voltage is always zero. The -, or inverting input, is the one that is actively used. Thus, we establish that the inverting input, which is also the junction of the input and feedback resistors, must operate as a virtual ground in order to keep the output voltage within bounds. So far, so good, but what about the actual voltage gain? It cant possibly be infinite, and if it isnt infinite, there must be some non-zero input voltage to produce a non-zero output voltage. In fact, the typical open-loop voltage gain for the 741 is 200,000. This does not mean that every such device has a gain of 200,000, however. What is guaranteed is that the commercial version (the 741C) will have a minimum gain of 20,000. The military version is more stringently selected, and will have a minimum voltage gain of 50,000. For the 741C, then, with a maximum output voltage of  ±10 volts, the maximum input voltage required at the inverting input can never be more than  ±10/20,000 =  ±0.0005 volt, or 0.5 milli volts. Typical measurement accuracy uses three significant digits, so we would measure voltages from 0.00 volts to  ±10.00 volts. The maximum input voltage is more than an order of magnitude smaller than this, and hence is insignificant in a typical analog computer. But what about input bias current? Surely the IC requires at leastsomesmall amount of input current? Well, yes, it does. The 741C requires a typical input bias current of 80 nA (thats nano Amperes, where 1nA=10-9A). The maximum input bias current for the 741C is 500nA, or 0.5 µA. So how do we use this information to minimize the errors it could cause into insignificance? Well, lets consider the resistance that would be required for this current to cause a significant voltage drop. If we keep the voltage error small enough, we can ignore it as immeasurable. This means we must keep the values of Rinand Rfas small as possible, consistent with proper operation of the circuit. At the same time, we cannot make them too small, or the op amp itself will be overloaded. For proper operation, the total load resistance at the 741 output should not be smaller than 2000 ohms, or 2k. This amounts to a maximum output current of 5 mA at 10 volts output. This means that the output resistance of the op amp is not the desired zero ohms. However, as long as you dont draw too much current from the output, the use of heavy negative feedback has an added benefit: It makes the op amp behaveas ifit had zero output resistance. That is, any internal resistance will simply mean that the op amp must produce an internal voltage enough higher than the calculated value so that the final output voltage will be the calculated value. So what if we make our input and feedback resistors about 10k each? Then the current demand on the output is only 1 mA at 10 volts, leaving plenty of capacity for additional inputs. And the voltage caused by the input bias current wont exceed 10,000-0.5-10-6=0.005volt. This is half of the least significant digit of our measurement capability, which is not as good as we would like, but will do. Also, this is the absolute worst-case situation; most practical applications wont see an error this big. In addition, the input bias current applies equally to both inputs. This is the reason for the resistor connecting the + input to ground. If this resistor is close in value to the parallel combination of Rin and Rf, the same voltage error will be generated at the two inputs, and will therefore be cancelled out, or very nearly. Thus, we can relegate this problem to true insignificance by means of correct circuit design and careful choice of component values. The 741 does also have two error characteristics, calledinput offset voltageandinput offset current, which define the inherent errors which may exist between the two inputs to the IC. However, the 741 also has the means for balancing these variations out, so the actual errors are minimized or eliminated, thus once again removing them from significance. A problem with any op amp is a limited frequency response. The higher the gain of the complete circuit, the lower the working frequency response. This is one reason an overall gain of 20 is a practical limit. (Another reason is that the input and feedback resistors become too different from each other.) Also, the standard 741 has aslew rateof 0.5v/ µs. This means that the output voltage cannot change any faster than this. The newer generation of op amps, such as the 741S, have a slew rate more like 5v/ µs, and hence can operate over the entire audio range of frequencies without serious problems. Classification of Operational Amplifier: Op-amps may be classified by their construction: discrete (built from individualtransistorsortubes/valves) IC (fabricated in anIntegrated circuit) most common hybrid IC op-amps may be classified in many ways, including: Military, Industrial, or Commercial grade (for example: the LM301 is the commercial grade version of the LM101, the LM201 is the industrial version). This may defineoperating temperatureranges and other environmental or quality factors. Classification by package type may also affect environmental hardiness, as well as manufacturing options;DIP, and other through-hole packages are tending to be replaced bySurface-mount devices. Classification by internal compensation: op-amps may suffer from high frequencyinstabilityin somenegative feedbackcircuits unless a small compensation capacitor modifies the phase- and frequency- responses; op-amps with capacitor built in are termedcompensated, or perhaps compensated forclosed-loopgains down to (say) 5, others: uncompensated. Single, dual and quad versions of many commercial op-amp IC are available, meaning 1, 2 or 4 operational amplifiers are included in the same package. Rail-to-rail input (and/or output) op-amps can work with input (and/or output) signals very close to the power supply rails. CMOSop-amps (such as the CA3140E) provide extremely high input resistances, higher thanJFET-input op-amps, which are normally higher thanbipolar-input op-amps. Other varieties of op-amp include programmable op-amps (simply meaning the quiescent current, gain, and bandwidth and so on can be adjusted slightly by an external resistor). Manufacturers often tabulate their op-amps according to purpose, such as low-noise pre-amplifiers, wide bandwidth amplifiers, and so on. Single-Ended Inputs With single-ended inputs you connect one wire from each signal source to the data acquisition interface the Micro link. The measurement is the difference between the signal and the ground or earth at the Micro link. This method relies on the signal source being grounded (earthed), and the signal sources ground and the Micro links ground having the same value. Differences in Ground Levels We think of the ground as a constant 0V, but in reality the ground, or earth, is at a different level in different places. The closer together the places, the more likely the ground level will be the same. Make a connection between two grounds and the difference in levels can drive large currents, known as earth or ground loops. This can lead to errors when using single-ended inputs. Noise Errors Single-ended inputs are sensitive to noise errors. Noise (unwanted signal contamination) is added because signal wires act as aerials, picking up environmental electrical activity. With single-ended inputs you have no way of distinguishing between the signal and the noise. The ground and noise problems can be solved by differential inputs. Differential Inputs With differential inputs, two signal wires run from each signal source to the Microlink. One goes to a + input and one to a input. Two high-impedance amplifiers monitor the voltage between the input and the interface ground. The outputs of the two amplifiers are then subtracted by a third amplifier to give the difference between the + and inputs, meaning that any voltage common to both wires is removed. This can solve both of the problems caused by single-ended connections. It means that differences in grounds are irrelevant (as long as they arent too large for the amplifier to handle). It also reduces noise twisting wires together will ensure that any noise picked up will be the same for each wire. Floating Signals A common problem when using differential inputs is neglecting any connection to ground. For example, battery-powered instruments and thermocouples have no connection to a buildings ground. You could connect a battery, for instance, between the Micro links + and inputs. The 2 input amplifiers will try to monitor the voltages + to earth and to ground. However, as there is no connection between the battery and ground, these voltages to ground could be any value and may be too large for the amplifier to handle. For these floating signal sources you should provide a reference. The Micro link has a socket labelled 0V. Run a wire from, say, the wire to this OV socket, either directly or via a resistor. (If your signal source is itself grounded dont make a connection to the Micro links 0V socket.) Amplifier Ability and Operating Range The three amplifiers used for differential inputs are collectively known as an instrumentation amplifier. Ideally, as previously described, any voltage common to both wires (common mode voltage) is cancelled. In practice the two input amplifiers are not perfectly matched so a fraction of the common mode voltage may appear. How closely the instrumentation amplifier approaches the ideal is expressed as the common mode rejection ratio (CMRR). This is the reciprocal of the fraction let through and is usually given in decibels. The higher the rejection ratio the better. Another specification to look for is the common mode range. This is the maximum contamination voltage with which the amplifier can cope. If the difference in ground levels between your interface and signal source exceeds this value, your measurement will be inaccurate. Less Signals with Differential Inputs? An obvious disadvantage of differential inputs is that you need twice as many wires, so you can connect only half the number of signals, compared to single-ended inputs. Should you decide that single-ended inputs are OK for you if you have short signal wires, close together signal sources, and signals larger than around 100 mV for e.g. you can use differential inputs in single-ended mode. To do this short one of the signal wires (usually the input) to the Micro link V input. Differential inputs, therefore, give you the option of either mode. Op-Amp Characteristics: A very typical commercial IC op amp circuit is the 741. This IC has been available for many years, and a number of variations have been developed to help minimize the errors inherent in its construction and operation. Nevertheless, the analysis we will perform here using the 741 will apply to any other IC op amp, if you take into account the actual parameters of the device you are actually using. Therefore, we will use the 741 as our example IC op amp. A differential amplifier connected as an op amp. To the right is a circuit using the 741 op amp IC, with the input and feedback resistors that are required for this circuit to operate properly in an analog computer. Note that there are actually two inputs to the amplifier, designated + and - in the figure. This is because the 741, like all IC op amps of this type, is in fact a differential amplifier. Thus, the output voltage is determined by thedifferencebetween the two input voltages. The +, or non-inverting input, is grounded through a resistor as shown. Thus, its input voltage is always zero. The -, or inverting input, is the one that is actively used. Thus, we establish that the inverting input, which is also the junction of the input and feedback resistors, must operate as a virtual ground in order t