Monday, December 30, 2019

The Current Climate Of K 12 Education - 706 Words

With the continuing trend of external accountability pressures the position of school principal has become laborious. Professors Christopher Branson and Steven Jay Gross (2014) believe that the current climate of K-12 education requires â€Å"leaders with ethical codes that are deep, innate, and instinctive, so that they will not lose direction in the face of uncertainty or external pressure† (p. 2). Accordingly, the time is ripe for school leaders to lead with an innate ethical framework. Yet, Branson (2014a) argues that ethical leadership does not result from an innate characteristic that an individual possess, rather a school principal must learn to become an ethical leader. Furthermore, Branson (2014c) asserts that ethical leadership â€Å"is an achievement and not a given. A leader has to strive to become an ethical leader, as it is unlikely to happen automatically† (p. 294). In short, the challenge and demand for today’s school districts is to find and cult ivate ethical school leaders. The position of school principal’s holding the status of â€Å"professional† was highly sought and eventually established during the 20th and the 21st century. With this in mind, philosopher Sigurdur Kristinsson (2014) asserts that because school principals are professional’s, the actions taken by educational leaders are â€Å"inherently ethical.† The basic argument being made by Kristinsson (2014) is that because all professions are essentially ethical and educational leadership is a profession, then theShow MoreRelatedSignificance of the K to 12 Curriculum from the BEC Curriculum1525 Words   |  7 PagesThe K to 12 Program covers Kindergarten and 12 years of basic education (six years of primary education, four years of Junior High School, and two years of Senior High School [SHS]) to provide sufficient time for mastery of concepts and skills, develop lifelong learners, and prepare graduates for tertiary education, middle-level skills development, empl oyment, and entrepreneurship. This program of the government have six salient features, first is the strengthening of early childhood education, secondRead MoreModern K 12 Schools : Implementing Innovative Pedagogical Practices Essay1128 Words   |  5 PagesModern K-12 schools are tasked with implementing innovative pedagogical practices to meet the needs of today’s digital learners. Consequently, K-12 schools are dedicating a significant amount of time and resources to professional development toward the cultivation of more creative learning environments. Despite such investments, most K-12 schools are far removed from implementing effective teacher improvement programs toward the development of organizational cultures of ongoing learning (The NewRead MoreThe Common Core State Standards930 Words   |  4 PagesI am assuming the role of a principal and I am questioning the support of the Common Core State Standards (CCSS) within my school environment. Based on the information in Issues in K-12 Educatio n Case Study Document 5, there are numerous issues concerning CCSS that a principal must consider for their school to be successful. These issues include: federal jurisdiction over curricula, the time allotted for implementation of federal standards, the impact of test results on professional developmentRead MoreIn This Autoethnographic Narrative Study, I Relay My Lived1173 Words   |  5 Pageseducator in a high school and the obstacles in gathering diverse art education materials on race and gender. The absence of Black female artists artwork in the K-12 art education classroom fits within a broader array expounding on the White gaze and the differences of how we look and how we see people. Therefore, this study is informed by the literature and theories related to the White gaze of Black women, feminist art education, and intersectionality (Collins 2000, Lorde, 2014; Thornton ZambranaRead MoreCorrelation Between School Culture And Student Performance Essay2561 Words   |  1 1 Pagesexamine all decisions made in education. Whether it is the implementation of national standards such as common core or state standardized testing, all stakeholders have a voice in improving student learning. In recent years the focus has been on the improvement of teaching, but the shift from teaching to student learning is taking hold with educators across the nation. This change in mindset from teaching to learning is significant and has the potential to change education as we know it. No matterRead MoreSocial Emotional Learning Essay827 Words   |  4 Pagesuse in Wilton Public Schools across all tiers of intervention. Thus far, the committee has set goals, reviewed protocols for meetings, researched current practices amongst the building and discussed curricular options. The committee is comprised of staff from every building and discipline as well as the Assistant Superintendent and the School Climate Advisor. This summer we met as a sub-committee to review to examine the Social Emotional Learning (SEL) goals, standards, benchmarks and performanceRead MoreMarine Ecosystems: Coral Reefs1349 Words   |  6 Pagesapproximately 284,300 km2 (Spalding Ravilious et al., 2001) providing a home for 25% of all marine life. An increase in greenhouse gasses in our atmosphere is occurring due to the increase in population and burning of fossil fuels, this is a major cause of climate change. The average global temperature is rising, with 71% of the earth being water; our oceans temperatures are greatly affected. The optimum temperature for a reef to maximise its productivity is between 26-27oC. Very few reefs exist in watersRead MoreStrategies Of Effective Instructional Leadership1714 Words   |  7 PagesWahlstrom, 2004; Robinson, Lloyd, Rowe, 2008) and standards for education leadership programs (National Policy Board for Educational Administration [NPBEA], 2002, 2011) unanimously confirmed the significance of the instructional leadership skills in running an educational institution. Thus, principals performing instructional leadership are the key elements in development circle of an educational institution. Correspondingly, the current paper aims to elucidate approaches to become a positively impactfulRead MoreImpact Of Biodiversity On The Environment1323 Words   |  6 Pagesfor instance, means that the process of climate regulation performed by ecosystems and their correlation will be threatened and disrupted. As a result, it will intensify problems with the biodiversity and lead to further extinction of many species. Nonetheless, researchers agree that it is difficult to predict exact impacts of biodiversity loss on the environment and the combined effect of the biodiversity loss, degradation of the environment, and climate change. The latter three phenomena may intensifyRead MoreSustainable Energy And The Hot Air1640 Words   |  7 PagesEnergy – Without The Hot Air† by David J.C. Mackay focused on the current dependency on fossil fuels today, which is not sustainable. In fact, the majority of developed countries solely burn fossil fuels as their source of energy. There are three main factors why this is bad. First, the quantity of fossil fuels are not infinite, eventually reserves will be depleted. Second, it is proven that burning fossil fuels influences climate change and global warming. Third, in the case of Britain and many

Sunday, December 22, 2019

The Health History Of A Student At The University Of Arizona

Introduction This paper will look at the health history of a student at the University of Arizona in the BSN program. This paper will explore the risks this student has of contracting diabetes mellitus due to a predisposition in her family history. The reason for the disease, patterns, risk, and preventative measures will be discussed and explained through the paper. Many people in the world suffer from type II diabetes [diabetes mellitus (DM)]. This student explored her health history back tracing diseases through her sibling, parents, aunts, uncles, and grandparents. This disease has a genetic component, but is also about lifestyle and choices that can be made to prevent the severity of this disease. Pathophysiology Diabetes†¦show more content†¦739). These are all genetic factors that contribute to potentially develop diabetes type II mellitus. These genetic factors alone are not enough to contract diabetes there needs to be environmental factors/life choices. Environmental factors include â€Å"obesity, hypertension, and metabolic syndrome† (McCane, 2014, p. 739). When a person has the environmental â€Å"risk factors for type II diabetes with insulin resistance, only those who have the genetic predisposition to beta cell dysfunction will develop type II diabetes† (McCane, 2014, p. 739). This means that a person who is not considered overweight, but has hypertension or does not live a healthy lifestyle and is predisposed can develop this disease as well. This is a rare occurrence in type II because â€Å"obesity is present in 60-80% of those with type II diabetes† (McCane, 2014, p. 739). Being obese contributes to the development of diabetes in five ways. These five ways are â€Å" 1. Adipokines are hormones produced by adipose tissue. /†¦/ Adipokines have effects not only on tissues but [also] on the hypothalamic and pancreatic function. /†¦/ 2. Elevated serum free fatty acids and high intracellular deposits of triglycerides and cholesterol. These lead to metabolic overload with interfere of insulin signaling and a decrease in tissue response to insulin. 3. Obesity causes release of inflammatory cytokines. /†¦/ These play an important role in the genesis of a fatty liver [which impairs the function]. 4.

Saturday, December 14, 2019

First modern solar cell Free Essays

The first modern solar cell In 1954, the first modern silicon cells raised by Bell Labs, then it shown at the National Academic of Science meeting. Moreover, this kind of cell can make 6 percent efficiency. Then, the New York Time come up with that the cell would lead to a source of â€Å"Limitless energy of the sun†. We will write a custom essay sample on First modern solar cell or any similar topic only for you Order Now In 1955, the Western Electric created very significant solar cell technologies. The technology start to use in makes solar cells. In 1957, the ATT telecom company used the â€Å"solar battery’ for their cell phones. Hoffman Electronics created about 8 percent efficient solar cell. Thinking about investing in a solar array but concerned about the lifespan of photovoltaic cells? Consider this: the world’s oldest solar panel † a 60 year-old crystal ball-like contraption † still works. The panel was built by a British science teacher who wanted to prove the novel idea that sunlight could be converted into electricity. Of course, the panel doesn’t produce much electricity-Just 1. 5 volts of electricity in direct sunlight, or enough to power a digital watch. And while todays panels only need indirect sunlight to function, the 60 year-old version requires direct sunlight. Still, the selenium-based panel is surprisingly similar to current models. The half century-old device is the first example of a modern solar panel, but it isn’t the first piece of solar technology. That distinction goes to Charles Fritts, who built the first solar cell in 1883. Want to check out the panel for yourself? It’s currently on display at Antiques for Everyone, a British antique event. How to cite First modern solar cell, Papers

Friday, December 6, 2019

Should Downloading Music Be Illegal. free essay sample

I have some comments about it I would like to acknowledge about it: Firstly when you mention that you advocate a culture In which people actually want to spend money on music, but I actually think we should advocate a culture where everybody listens to music and not Just the ones who have a computer and and a bank account, I believe that music should be a right and not a privilege and everybody should want to willingly listen to music.Then you argue that people value music but they dont value it in the sense that they will willingly fork over $1 for a song, I have more than 2 thousand songs in my library, that is equal to 2 thousand dollars and I really dont have that extra money to spend and people usually dont Eke to spend their money on things they can get for free. I would much rather use that money to buy something else and if we had to pay for every single song we would like to listen to our music library would be much smaller and we could not enjoy music as much as we enjoy It when we have a large variety ofIt. We will write a custom essay sample on Should Downloading Music Be Illegal. or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page For the consumer, music Is not a product or a service. They pay for physical copies music such as Cads, they pay for music sheets or for subscriptions to music services, but they dont pay for a song by itself. After that you state that artists now have no money to keep recording music and have to go on tours to get the money. I do agree that some artist that are not yet discovered should get support from their fans so they could keep recording music, but arent musicians supposed to be doing music because its their passion?They are to supposed to go into the business because they want money and fame even though I dont see the artist at the top of the charts starving to death. Music Is about passion and the ones who are recording music are supposed to want to bring their music to all kinds of people so they can enjoy It and the musician Is supposed to be satisfied with that and not be crushed because they are not the cover of a magazine. I also think that tours are a great thing, why listen to a record when you can go out and the real human behind the voice live and enjoy it more closely.Its clear that everybody thinks music should be free, because its going to sell everywhere else. Why should the music industry care whether the money comes from a tour with $100 in profits or the exact same amount is broug ht in from CD purchases? In the end, it doesnt matter, money is still coming in and can be used to record more music. Then you talk about how music labels are closing because the lack of money they are getting but I actually think that record labels are trying to turn music into gold, music cording labels are getting a large cut of the artists money and are overcharging.The artist who are not yet discovered cant record a good album because the labels are asking for absurd quantities of money which the artist cant pay, so the label closes and the villous circle starts again elsewhere. I think labels should spend more time developing the artists because they would have a stake in them that extended n music and be looking for money and a the same time state that they truly care about the musicians.In conclusion I think that we do need to support our artists, but that could be done a million ways other than paying an overpriced dollar for a song. Ninth the internet now how can we be surprised when people now expect to get their music online for free? The internet file sharing and the advantages we now have in technology I see no way to make the clock turned back and force people to start paying again. So the business has to get creative and evolve away from the sale of recorded music and start receiving money in other ways.

Friday, November 29, 2019

Scholarship Boy Essay Research Paper Scholarship Boy free essay sample

Scholarship Boy Essay, Research Paper Scholarship Boy You re a pretty lucky child to hold received this scholarship to that private school in Virginia. Mrs. Casas spoke to me in her really serious tone of voice, which caused my chocolate-brown eyes to concentrate profoundly on her intense expression. Esther Casas was a member of the I Have a Dream Foundation, and the adult female who made it possible for me to be admitted to VES by giving the school good word about my work ethic and possible that I carried within my little frame. Yeah, I m a pretty lucky. I responded with a flicker in my immature voice because I was excited and felt lucky. Excited I was, because it was my first clip go toing a boarding school, and everything seemed so cryptic to me that I could non wait another second of clip to be present in Virginia, a topographic point that I knew nil approximately but merely that it was located in the eastern portion of the US. We will write a custom essay sample on Scholarship Boy Essay Research Paper Scholarship Boy or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page When the clip came to eventually get down this great new experience, I was overcome with felicity that the enigma would be solved by a twosome of hours of winging above the endless cragged land. When I arrived on this campus, I found it rather surprisingly quiet and peaceable. My journey to this beautiful green campus had started four old ages antecedently in Mrs. Brown s 6th class home room category at Markham Junior High. Mrs. Brown was asked by the I Have a Dream disposal to pick 10 names of pupils in her category who she thought were good all around pupils and besides who seemed interested in go oning their instruction. Mrs. Brown felt that I had the demands to measure up for the lucky 10 who would shortly go Dreamers. Bing a Dreamer was one of the best things that could go on to me while I was seeking to turn up in a community of force and offense. While other childs were out hanging at the corners, the IHAD would pick up a group of us in a spotless, long white new wave with ma rkers on the side that read I Have A Dream Foundation, Los Angeles in large black letters. This new wave would weave is manner through the crowded smoggy streets to a topographic point where our instruction would be expanded. This topographic point was a big room located inside a Great Western bank. The room indoors contained computing machines, books, coachs, and other helpful beginnings that would dispute our heads and increase our cognition. The IHAD non merely tried to increase our instruction, but the foundation besides manage to take us on trips to topographic points that I had neer seen earlier such as the Big Bear mountains in California or to operas such as the Carmen. The feeling that I got from this plan was that they were seeking to open up the universe for me in many ways so that I would hold a wider position about things in life. Since the first twenty-four hours at VES everything happened the manner a new pupil would desire his first twelvemonth to be. During this twe lvemonth I maintained a steady norm of 83 % ; I had a batch of friends ; the instructors were all polite and helpful when needed, and I had a large function in athletic as a member of the varsity association football squad, j.v. hoops squad, and the path Te am where I broke a school record in the 800-meter relay. I felt good about my achievements my first twelvemonth and there were no complains from any of the instructors or disposal because I was populating up to the outlooks they had for a scholarship male child. About the half manner into my sophomore, the scholarship male child began to take different determinations and rapidly drew the attending of some module members who looked upon him as person with a bad, violent, and negative attitude. This all happened when I and a few other pupils got into a large bash with other pupils from E.C. Glass, and I decided to draw out a knife. I pulled out the knife to protect my friends and me from the oppositions, savages who were acquiring ready to contend our bantam group of four because we were from a prep school. The school did non see my actions as a signifier of protection for our group ; alternatively they saw it as a delinquent reaction in me. I had violated the school regulations and was suspended for a twenty-four hours of deadening categories. I had let their outlooks down ; I wasn t to the full fulfilling their hopes. You can make better than this. Mr. Mundy, my adviser, spoke to me in his deep powerful voice as he handed me my agenda for th e undermentioned trimester. Passing me the light piece of paper, Mr. Mundy walked away go forthing me entirely in a universe of enigmas that had to be discovered. I though to myself standing in the blocks of dirty clay below my cold pess, an 80 % norm is non the best class in the school but is non near to the worst. I felt that my classs were reasonably nice, but Mr. Mundy did non accept that fact and left me with no room to speak. He turned his dorsum on me. Since the embarrassment with Mr. Mundy, I began to believe that being at a private school on a scholarship wasn t the best thing, and decidedly non the lucky state of affairs that Mrs. Casas had told me and I had thought. It seemed as if all eyes were on me, the scholarship male child from Watts, watching every individual measure and action I made to do certain that I didn t cross the boundaries that they didn t expect me to traverse. Then the ideas of other pupils began to twirl around my busy head. If it had been another pupi l perpetrating a minor discourtesy or acquiring bad classs, he wouldn T hold had to worry every bit much because he came to this school with no outlooks from instructors, but merely from parents and friends. It felt as though I carried a heavy load on my dorsum to make good because it was expected of me. It was non merely that I wanted to make good or that my household expected this of me. I knew the whole clip that I was working hard for myself and cipher else, but I felt as though excessively much flawlessness was required of me because I was a different type of pupil. To this twenty-four hours I still find myself believing that instructors expect more out of me because I came here in particular fortunes and with really high vitamin E outlooks for my hereafter that I felt had to carry through. In world I do everything for my ain will and because of my love for my household and friends but cipher else.

Monday, November 25, 2019

The Avro Arrow - There Never Was essays

The Avro Arrow - There Never Was essays It was supposed to be the biggest, fastest, and most powerful plane that the world, and especially Canada, had ever laid its eyes upon. It was in a class of its own, at least twenty years ahead of any other country technology-wise. It was to be the most technologically advanced supersonic jet fighter in the world, a combination of sheer brain and willpower of 14 000 world-class engineers and technicians. And yet, the Avro Arrow, which gave Canadians a sense of pride bigger than itself, was never meant to be. Formally named the CF-105, the Avro Arrow was a dream denied. The Arrow was built by A.V. Roe Canada to counterattack the air superiority of the Soviet bombers that would presumably carry nuclear warheads over North America. Ironically enough, the day it was unveiled, the public had its eye fixed on the launch of the first Sputnik, a product that would jumpstart the Soviet Unions space race. However, the Arrow didnt stay unnoticed for very long. It was soon the talk of th e town in various parts of the world. Unfortunately, the Avro Arrow didnt last very long. On February 20, 1959, John Diefenbaker, then the Prime Minister of Canada, stood up in the House of Commons and stated, The government of Canada has carefully examined and re-examined the probable need for the Arrow aircraft... The conclusion arrived at is that the development of the aircraft...should be terminated now (Campagna, Palmiro pg.54). This announcement came as a shock to everyone, and suddenly 14 000 very highly qualified engineers were left on the streets. The British, the French and the Americans wasted no time in grabbing these individuals, who later became instrumental in helping the Americans putting a man on the moon, as well as the development of the Anglo-French Concorde. Also, the Diefenbaker government immediately ordered the scrapping of the six existing aircraft and the 34 still in the production stage. Also, all rec...

Thursday, November 21, 2019

Customer service problem solving and alcohol management Essay

Customer service problem solving and alcohol management - Essay Example In this context, it is significant to develop a cohesive and strong staff. We train the employees in reference to the ways that we feel best for them to deal with the customers. Despite the fact that we realize that the staff has some prior experience before coming to work for us, we prefer to give them additional training so as to bring them up to par with the standards of restaurant management. We equip the staffs with the necessary information and skills that are critical in their line of work in the restaurant (Pattie 89). We are aware that customers are of different characteristics. In this sense, it is important to prepare for instances where one has to deal with customers of all types. There are customers who are stubborn while others are angry and in some cases there are violent ones. These are some of the worst customers that one has to deal with, but there are others who are sick or injured and these are calmer ones. Therefore, we also train the staff so as to aid them in dealing with these people. We advise the staff to make sure that they pay keen attention to the concerns of the customers and this means listening to the customers. Listening is an important step in the quest to find a resolution to the problems that affect the customers. We advise the staff that it is imperative to listen to the customers in order to understand their problem. After establishing the problem, it is also important to acknowledge the severity or fatality of the matter. Thus, the most applicable negotiating skills are listening and acknowledging the root of the problem (Pattie 127). The restaurant has several facilities that offer spots for relaxation for the clients. There is a bar that is fully stocked with all brands of alcohol ranging from wines, whiskey, vodka, gins among others. The bar is mostly for the middle age individuals who are looking for a place to relax as they

Wednesday, November 20, 2019

Final Report and Ratios Essay Example | Topics and Well Written Essays - 250 words

Final Report and Ratios - Essay Example ive when compared to that of Lowe’s. Total debt ratio is more than 1 in the year 2009 and 2008 for Home depot but it’s less than 1 for Lowe’s in the year 2009 and 2008, which suggests that in case of liquidation, shareholders will be left with nothing in case of Home Depot as debt holders would be paid first. Lowe’s also has a better cover for the interest payables, as the times interest earned ratio which stands at 10.93 is far ahead when compared to that of Home Depot which stands at only 6.89. Lowe’s cash conversion is of particular significance because the operating profit attributable to shareholders is converted into cash, which could be paid to investors without affecting the business, more efficiently and effectively when compared to that of Home Depot. References Home Depot Annual Report, 31 January 2010, Web site: http://www.homedepot.com/ Lowe’s Annual Report, 31 January 2010, Web site: www.lowes.com

Monday, November 18, 2019

Does High Perception of School Environment Correlate with Teacher Essay

Does High Perception of School Environment Correlate with Teacher Performance - Essay Example coming in, many educators have approached this researcher on concerns pertaining to administration support, discipline, and overall knowledge to serve their students. Some expressed concerns of not being equipped or trained properly to perform their job expectations. As the â€Å"new person† to the school, I have faced with some of the same issues. In this study, the researcher will use stratified random sampling to find his data. Stratified random sampling involves looking at distinct subgroups while obtaining data (CustomInsight, n.d.). For the research question, â€Å"Does High Perception of School Environment Correlate with Teacher Performance,† this researcher will be looking at two groups: regular education teachers and special education teachers. Atha Elementary has 9 special education teachers and 34 regular education teachers. The objective is to get a clear view on how educators perceive their environment. Therefore, a likert-scale must be utilized (Super Survey, 2007). This research after attitudinal information: describes how a person thinks or feels about something. Educators will be able to rate their feelings on a scale of 1 to 5 as shown below. In order to select the appropriate method of data recording one must first understand variables. Variables are used in the study of statistics. A variable is a characteristic that can take more than one set of values that numerical measures can be assigned to: height, age, income, country, grades, and housing type (Statistics Canada, 2011). Quantitatively, this writer will give a survey to collect initial perception of the school before professional developments are provided or major concerns are addressed. Surveys will be given to two mixed groups of elementary school educators (both groups will contain an equal amount of special and regular education teachers). Group A labeled (control group) will not be provided with options on professional development, will only meet with assistant principals at their

Saturday, November 16, 2019

Tcp Congestion Control Methods Tutorial Information Technology Essay

Tcp Congestion Control Methods Tutorial Information Technology Essay Transmission Control Protocol (TCP) is one of the two core protocols of the Internet protocol suite. Together with IP, they constitute the backbone stack of many internet applications like the World Wide Web, the e-mail and file transfer (FTP). Its main function is to provide a reliable stream service utilizing an unreliable packet delivery system inherited by its underlying IP layer. By the term reliable, we mean the reliable ordered delivery of a stream of bytes from one peer to another that runs the same TCP protocol stack. To add this substantial functionality and reliability, TCP imposes complexity. It is a much more complex protocol than its underlying IP protocol. The main mechanism TCP uses to offer reliability is the positive acknowledgement and retransmission scheme. Transmitted segments must be acknowledged and if there is a loss, a retransmission takes place. To make the network utilization more efficient, instead of transmitting each segment only after reception of an acknowledgement for the previously transmitted segment, TCP uses the concept of a window. The window includes all those segments that are allowed to be sent without waiting for a new acknowledgment. TCP allows end to end adjustment of the data flow a sender introduces to the network by varying the window size. How can a sender know what is the suitable window size? A receiver indicates it in a window advertisement which comes to the sender as part of the acknowledgment. Since modern internet applications are hungry for bandwidth, there is a high possibility that network becomes congested at some time. Routers have a finite storage capacity for handling IP packets. If the packet flow rate becomes excessive, routerà ¢Ã¢â€š ¬Ã¢â€ž ¢s queue buffers will become full and their software will start to discard any new packets arrived. This has a negative impact in the TCP operation and performance in general. Increased delays and losses will impose retransmissions and hence increased traffic. In its turn, increased traffic will make congestion more severe and in this way, Internet will experience what is known as congestion collapse, exhibiting a performance fall of several orders of magnitude. To overcome this problem, TCP uses many mechanisms-algorithms to avoid congestion collapse and achieve high performance. The main idea behind these algorithms is to control the rate of data entering the network and keep it below a threshold rate. If this threshold we re to be crossed, a new collapse phase could be triggered. Data senders can infer from an increasing number of delays that the network is congested and so adjust the flow in order to mitigate the phenomenon and give the network the necessary time to clear the queues and recover from congestion. TCP Congestion Algorithms RFC5681 describes four congestion control algorithms. Slow start, congestion avoidance, fast retransmit and fast recovery. All these algorithms work with the admission that sender infers network congestion by observing segment losses. As mentioned above, in TCP, receiverà ¢Ã¢â€š ¬Ã¢â€ž ¢s buffer capability can be advertised backwards in the acknowledgement messages. This helps the sender to adjust its window size. Congestion algorithms introduce a second limit which is named congestion window. This new window is used for restricting the data flow of sender below the limit that main window determines. Actually, in a congested phase, the TCP window size used is the minimum value between the normal and congestion windows sizes. Reducing the congestion window reduces the injecting data flow to the network. Congestion avoidance algorithm reduces the congestion window by half upon each segment loss. For those segments that remain in the window, it also backs off the retransmission timer exponentially. In this way, quick and significant traffic reduction is achieved. Upon loss of successive segments, the algorithm uses an exponential rate to drop the data flow and increase the retransmission timers. This gives enough time for the network to recover and become stable again. Slow start algorithm is used when the network has recovered from the congestion and the windows start to increase again. To prevent oscillation between network congestion and normal conditions coming immediately after recovery, slow start indicates that congestion window must start at the size of a single segment and increase by one segment for each acknowledgement arrived. This effectively doubles the transmitted segments during each successive round trip time. To avoid increasing the window size too quickly, once congestion window reaches one half of its size prior to congestion, TCP enters a congestion avoidance phase and the rate of increment is abruptly slowed down. During this phase, congestion window increases by just one segment and only after all segments in the current window have been acknowledged. Upon detection of a duplicate acknowledgment, sender cannot deduce if there was a loss or a simple delay of a segment. If ordinary out-of-order conditions are present, one or two duplicate acknowledgements are typically expected. If however, sender receives three or more acknowledgements, it can infer that there is loss of segments due to congestion and so it retransmits the segment (indicated by the position of the acknowledgement in the byte stream) without waiting for the retransmission timer expiration. This constitutes the fast retransmit algorithm. Fast recovery follows fast retransmit algorithm and in the real TCP implementations these two algorithms are usually working together. Since reception of duplicate acknowledgements is a clear sign that data is still flowing in the receiver, fast recovery algorithm puts the sender in the congestion avoidance phase instead of the slow start phase. Therefore, if losses are not due to congestion, there will be a faster recovery of data flow without the penalty experienced by the use of slow start. However, fast recovery only works well for moderate congestion conditions. Newer algorithms Although the aforementioned four algorithms offer substantial congestion control, newer techniques have emerged in the bibliography as a result of extensive research in this specific area. These new algorithms try to build upon the old methods, enhancing TCP performance and increasing the responsiveness to congestion. One limitation of normal TCP operation is that if a transmitted segment is lost but subsequent segments in the same window are delivered normally, the receiver cannot send acknowledgements for these last segments. The reason for this is that receiver can acknowledge only contiguous bytes that it has received. Sender will be forced, once retransmission timer for the lost segment expires, to resend not only the lost segment, but all subsequent segments in the window too. This was identified as a potential case for improvement which led to the creation of the selective acknowledgments (SACK) algorithm (Jacobson and Braden, Oct. 1988). The algorithm helps to reduce the number of unnecessary retransmissions by allowing the receiver to send some feedback to the sender about the contiguous byte stream blocks it has already received. In order to take advantage of the new technique though, the two TCP endpoints must agree on using SACK upon negotiation (by using the option field of the TCP he ader). Two TCP original software implementations in the BSD Unix environment were named Tahoe and Reno. Tahoe includes the slow start, congestion avoidance and fast recovery algorithms whereas Reno includes all four basic algorithms described in the second section of this tutorial. NewReno is a slight modification of the Reno implementation and aims in boosting the performance during the fast retransmit and fast recovery phases. It is based on the notion of partial acknowledgements. In the case where multiple segments are dropped from a single window, sender enters fast retransmit phase and gets information about the retransmitted segments in terms of the first acknowledgment it gets. If only a single segment was dropped, then the acknowledgment will probably contain all segments previously transmitted before entering fast retransmit phase. If on the other hand, there were losses of multiple segments, the acknowledgment will be partial and will not contain all segments transmitted prior to fast retransmit phase entry. Using partial acknowledgements, fast recovery performance is enhanced as described in RFC2582. NewReno also improves round-trip and back-off timer calculations. In the literature, it is found that its main drawback is the poor performance in bursts of losses of segments within the same window (Wang and Shin, 2004). Non-TCP congestion control There are also some non-TCP techniques that can indirectly affect congestion control performance of TCP. These methods are not directly implemented in TCP software. The most popular technique of this kind is Random Early Detection (RED). In order to understand the method, one first has to consider what is called the global synchronization problem (D. Comer, 2000). Routers in the global Internet use the tail-drop policy for handling datagrams. When their input queue is full, any incoming datagram is discarded. Since datagrams are usually multiplexed in the Internet, severe problems can occur regarding congestion. Instead of dropping many segments of one TCP connection, tail-drop router policy actually causes single segment drops from many TCP connections. This, in turn, put the senders of these connections in slow start mode at almost the same time causing the global synchronization problem, which degrades performance considerably. To overcome this problem, RED (which is implemented in router software) defines two different thresholds that are associated with its internal queue, Tmin and Tmax. The following three rules govern the operation of RED It the queue size is less that Tmin, add any new incoming datagrams to it If the queue size is bigger that Tmax, drop any new incoming datagrams If the queue size is between Tmin and Tmax, randomly discard incoming datagrams with the help of a probability p. The main reason for this approach is to drop datagrams as congestion increases so as to avoid a queue overflow and a subsequent transition of many TCP connections to the slow start phase. As it is obvious, success of RED algorithm is based upon careful selection of the two thresholds Tmin and Tmax along with the probability p. Tmin must ensure high network utilization whereas Tmax must take into account the TCP round trip time so that it can accommodate the increase in queue size. Usually, Tmax is at least twice large as Tmin, or otherwise the same global synchronization problem may occur. Probability p computation is a complex task that is repeated for every new datagram. Non-linear schemes are used for this calculation in order to avoid overreacting to short bursts and protect TCP from unnecessary discards. These schemes usually take into account a weighted average queue size and use that size for determining the probability p. Details of RED are described in (S. Floyd and V. Jacob son, Aug. 1993). Research simulations show that RED works pretty well. It successfully handles congestion, eliminates the global synchronization problem that results from tail-drop policy seen before, and manages to allow short bursts without the need for extensive discards that could compromise TCP performance. When implemented by routers together with the TCP congestion control methods already built in the various network software implementations, it provides the necessary protection for network performance, securing its high utilization. Conclusions TCP performance is essential for providing true experience to single users, enterprises and everyone connected to the global Internet. One of the biggest challenges TCP faces as years come by, is congestion control (along with security which is another hot topic for TCP and other protocols). The original TCP standards described four methods that succeeded to almost eliminate congestion. As Internet increases in size and applications are becoming bandwidth hungry, new techniques that enhance inherent limitations of the four original algorithms are introduced and overall performance is kept in acceptable levels. Ongoing TCP research still focuses on congestion control and many new methods or variations are coming to fill any gaps that are gradually discovered by the ever-increasing Internet utilization.

Wednesday, November 13, 2019

What has the Internet done to Radio Listenership? :: Essays Papers

What has the Internet done to Radio Listenership? Annie McBride (name changed to protect the internationally famous) is a junior at Syracuse University who hails from the land of Guinness across the Atlantic. She has regularly kept in contact with her native land by listening to and calling the premier student run radio station in the Ireland, LSRfm at the Leeds University. She was an American correspondent who informed the listeners of LSM about the latest fads, movies, and television shows in the United States. The radio station is broadcast over the internet, and will be returning to the FM dial in Ireland in 2006. (lsmfm.com) LSMfm is part of a trend that has been growing since the late 1990s: internet radio broadcasting. Many radio stations, like LSM in Leeds, Ireland and z89 in Syracuse, New York, have live audio streams of their broadcasts in real time. This allows anyone on the planet to listen to their favorite local station, no matter how far away from home they may be. The internet also allows for access to an extraordinary range of music. All of this is contributing to radio losing its foothold in society to the internet. One of the main reasons that the internet has become such a popular source for music is its diversity. Kim Vasey (2005) says â€Å"†¦Internet radio (has) brought alternative music choices that mostly cannot be found on the 'dial,'†¦Ã¢â‚¬  (Newswire Association, 2005). These days, terrestrial radio stations have to take into account a wide diversity in their listeners’ musical tastes. In order to satisfy everyone’s palette, â€Å"the best a station can hope to do is program it's content so it hits "the middle" which, inevitably leads to little risk taking and bland programming.† (Deitz, http://radio.about.com/) This bland programming is of course what the turnoff for most radio listeners is in the first place, driving them to other annals of consumption, mostly the internet. A study done by a consumer research company called NPD reveals online radio listening is on the rise. â€Å"The research from NPD centers around people listening to music on thei r computers. It points to 77.2% of users having moved in this direction, and 55.3 million now listening to radio online.†(Music Online http://www.audiographics.com/) The internet is the one of the leading alternatives to terrestrial radio because it is so ready to use. The software is extremely accessible, and it is rare, in this day and age, that a computer is not hooked up to the internet.