Monday, May 25, 2020

Statement of Purpose for Computer Science - 635 Words

My inclination to see logic helped me code right from high school. I still remember the â€Å"Computer Applications† course that I took, where despite learning very basic Java, I could write snippet programs. I was fascinated with loops and arrays and was surprised how easily I could learn to apply logic and get the required output. An undergraduate program in Information Science and Engineering gave me the exposure to core concepts of programming and hands on experience across categories like –utility applications, microprocessors and web applications. My skill of formulating algorithms and writing codes in required language to meet the requirements were being honed here. My programming abilities can be attested by the fact I scored more than 90% aggregate (top 2 in a class 120) for my entire practical courses. As the passion for programming grew, I could extend beyond academia and design and execute a basic Customer Relationship Management (CRM) application for my father’s business; build an Android game along the lines of â€Å"Wordament† – where the player had to find logic between numbers, amongst participating and winning various extracurricular activities. An academic project I undertook, Crowdsourcing in Intelligent Transportation System or Crowd-ITS on the Android mobile plat form, recorded crowd-sourced location data, I was enthralled how this information could be used to avoid traffic congestion and build better roads in urban areas. This project paved way for anShow MoreRelatedStatement of Purpose of Computer Science827 Words   |  3 PagesSTATEMENT OF PURPOSE Every generation has its own dimension. In the ages of Apes, man’s primary motive was to feed himself and so, he learned the means of hunting; In the Stone Age he learned means, which made his work easier and he invented tools in this pursuit; In the Iron Age he discovered technologies, he started manufacturing and later established business. This development saga of the man continued, always re-inventing him. Information is the dimension of the present age. How fast, how efficientRead MoreStatement of Purpose for Computer Science812 Words   |  3 PagesIt is universally agreeable that with the advent of Computer technology, every ambitious and enthusiastic individual is really obsessed with the idea of doing computer science at graduate level because it seems to have created a zeal and enthusiasm in the hearts of youth, particularly those who aspire to be marked as high achievers. I, for one, seem to have been enchanted by these computer applications as they have made the world smaller, speaking in terms of globalization. I have no hesitation toRead MoreStatement of Purpose Computer Science Essay773 Words   |  4 PagesSTATEMENT OF PURPOSE My four years of undergraduate studies in CS at PSG College of Technology, Coimbatore and my exposure and penchant for research have made the choice of further study, for me, an obvious one. My goal is to pursue a career in research, either in industry or in academia. Ten years from now, I envisage myself as a full-fledged research professional in an organization, or a faculty member at one of the leading universities. The first step towards my objective would be to pursueRead MoreA Statement of Purpose: Computer Science Essay545 Words   |  3 PagesStatement of Purpose Course applied: Computer Science My passion for Computers developed when my fingers felt the first touch of it. The abstruse world of computers fascinated me to penetrate the technology and learn more about it, when I was in my 6th grade. The passion for this ever changing technology of computers enthralled me to take up graduation in Computer Science, further to go for research in this stream. My ambition towards this subject andRead MoreStatement of Purpose: Master in Computer Science602 Words   |  2 Pages Statement of Purpose/Computer Science Master Playing games on my fathers computer as a child fascinated me in the way the computer works, how fast it develops, and now how the computer helps the world to communicate. It still amazes me in how fast computers change and how communication across the globe is enhanced with the computer. Computers have drastically changed how society lives and does business. Even small businesses can do global sales without leaving their location. With new strategiesRead MoreStatement of Purpose on Computer Science and Management614 Words   |  3 Pageshave been fascinated by technology since childhood. This motivated me to pursue my bachelor’s degree in the field of Computer Science, which exposed me to programming languages such as C, C++ and JAVA. I also learnt the concepts of Data Structures, Algorithm Analysis and Design, DBMS, Data Warehousing and Data Mining. My inclination towards exploring the practical domain of computers led to my involvement in many projects like ‘Virtual DOS using JAVA’, ‘Steganography’ and ‘Hotel Management System’Read MoreStatement of Purpose for Master in Computer Science540 Words   |  2 Pagesachievement and begin to replace youth with wisdom, innocence with understanding, and lack of purpose with self-actualization. -Bo Bennett I present upon myself a precious gift of â€Å"Curiosity† which made me what I am today in the field of Computer Science. The quote attributes to my tendency to pursue the path of knowledge and passion to reach this goal with due diligence and perseverance. I have chosen Computer Science as major during Bachelors and pruned the knowledge with industry experience at Tata ConsultancyRead MoreEssay on Statement of Purpose for a Masters of Computer Science940 Words   |  4 Pages Statement of Purpose Security of computer systems and networking has become an issue of extreme importance due to the rapid increase in Internet usage. Making computer systems and Internet more secure for the society is the goal that I have set for myself. I have continued to make serious efforts in this direction during my undergraduate education and presently at software industry. My urge to continue my efforts aggressively propelled my interests to pursue Masters of Computer Science at theRead MoreStatement of Purpose for a Masters Degree in Computer Science 798 Words   |  3 PagesMy decision to undertake a master’s degree stems from my aspiration to have greater knowledge about Computer Science, an avid interest in the field of Software Engineering and a stimulating research environment present at the University of Pennsylvania. By pursuing a graduate degree, I will be able to strengthen my knowledge base and also further my career prospects. One of the greatest discoveries in the past few decades has been the Internet. It has revolutionised how we live, made distanceRead MoreEssay on Statement of Purpose for MS in Computer Science640 Words   |  3 PagesPersonal Statement MS in Computer Science, University of Illinois Being naturally intrigued about Computers, I pursued my undergraduate studies in Computer Science and Engineering at College of Engineering Trivandrum, University of Kerala, India. I intend to do my higher education in Computer Science and would like to get enrolled into the Masters Program at University of Illinois at Urbana-Champaign starting Fall ‘14. My Interest in science started in early childhood. I was fascinated by

Thursday, May 14, 2020

Test Anxiety Understanding Some Of The Ways - 1623 Words

Exploiting the Pressure: understanding some of the ways in which test anxiety can develop within students. Imagine sitting in a small coffeehouse with a delicious coffee sitting close by, on a peaceful rainy day. This is the perfect time to stay inside and prepare for an upcoming exam. A large stack of color coded, handwritten note cards are filled with all the information discussed within the class, textbooks and notes are scattered. Hours go by, a great amount of studying and reviewing is done. The student continues to study for several days leading to the exam, but there is just one problem, this student suffers from test anxiety. Test anxiety can be defined as, â€Å" an unpleasant feeling or emotional state that has a psychological and†¦show more content†¦In a response to these alarming statistics, it is crucial that educators understand how test anxiety can develop in the classroom, are able to recognize anxious behavior within a student, and how to help a student work through his or her anxiety. There are many ways in which test anxiety can develop within a student, it is crucial to first analyze some of the key factors that may come in to play within a classroom setting. The authors of Test Anxiety: A Major Problem and What Can We Do About It, Kennedy T. Hill and Allen Wigfield state, discuss that motivational factors may exert as much influence on their school performance as do cognitive skills and abilities, (Hill, Wigfield 106). This statement opens the discussion over positive and negative motivations, that may have a significant effect on a student’s academic success. Through a personal interview with social/emotional/behavioral teacher, Donna Barron discusses some positive and negative inspiration she has experienced. She states, â€Å"I encourage my students to be encouragers and up lifters.† This means if there is a situation where the classroom environment becomes competitive, each student is re-enforced, especially when collectively learning. Howeve r, Barron does not disagree in allowing her students to have chances to earn prizes for good behavior, â€Å"I am pushing them to work for a chance to win pizza if they do their

Wednesday, May 6, 2020

Terrorism - 677 Words

TERRORISM Prof Nerove SEC 300 May 28, 2012 On the next couple of pages, I will be discussing terrorism as a threat to people and infrastructure. My discussion will include how individuals in private and public security can attribute to the prevention of terrorism within the U.S. terrorism is a threat that does not recognize borders and may affect states and peoples irrespective of their geographical location. Individuals and groups who believe that they can advance their political aims by using terror pose a serious threat to the democratic values of our societies and to the rights and freedoms of our citizens, especially by indiscriminately targeting innocent people. Acts of terrorism are criminal and unjustifiable, and must be†¦show more content†¦This would increase their strength and improve their ability to serve and protect the country. Security officers should stay alert for routine crimes or activities as red flags to possible terrorist planning (Hess, 2009). Police officers will need to extend their normal community policing activities, improve their handling of information, and protect vulnerable targets. Both private and public security will need to become more expert in crime prevention and security matters, and they will have to develop partnerships with businesses. Personally, I think that both public and private security has been doing a great job with assisting the country in the prevention of terrorist attacks. So far everyone that’s been trying to commit terrorist acts within our country has been stopped. The U.S. and their partners are attacking terrorist and their networks in a campaign of direct and continuous action by denying them their needs to operate and survive overseas. They are also being offensive at home, taking the fight to an enemy that exploits our open and diverse society, who hides among us, and tries to attack us from within (Hoffman, 1988). In conclusion, terrorism as a threat to people and infrastructure is considered to be very critical. The U.S i nfrastructure is potentially vulnerable to cyber- attacks. Most infrastructures are soShow MoreRelatedTerrorism : Terrorism And Terrorism1326 Words   |  6 Pagesallowing terrorism to be successful and continue. Terrorists gain power through the common, innocent people they attack. How the world responds to terrorist attacks determines whether or not terrorism will cease. The common people’s response to terrorism, the interest of the state, and the media’s role in terrorism all aide to terrorism’s success and its continuation in the future. How people willingly choose to respond to terrorist attacks defines terrorism and determines if terrorism will continueRead MoreTerrorism : Terrorism And Terrorism1126 Words   |  5 PagesTerrorism Have you ever had a fear for your family, your town, your country, or your world. How about the fear to have everything taken from you, destroyed, and not caring if it has hurt you or not? What about your fear and pain is, and can be someone else’s happiness? The fear of you being terrorized? That is terrorism. Someone else bringing fear and terrorizing you. That is a terrorist’s goal. Terrorism is common and is very difficult to stop. The government promises protection for the peopleRead MoreTerrorism : Terrorism And Terrorism1035 Words   |  5 PagesOver the past Century, terrorism has advanced from random killings to enormous plans for terrorist groups. To understand terrorism you must first define it. Terrorism as we all know it is hard to define and understand, and has many different definitions as it is used widely. The word terrorism stems from the word terror, which means to instill fear in. People become terrorists when they take the actions towards instilli ng fear and terror upon people to prove a certain point or agenda. Some terroristsRead MoreTerrorism : Terrorism And Terrorism1626 Words   |  7 PagesTerrorism can be categorized as â€Å"the use of intentionally indiscriminate violence as means to create terror, or fear, to achieve a political, religious, or ideological aim (Fortna).† Although there is no formal definition of terrorism, we typically associate the words terrorism and terrorists with acts of violence that are used unlawfully to intimidate in pursuance of political gain. Terrorists do not act at random, but rather use violence to maximize on fear and publicity with a specific goal inRead MoreTerrorism And Terrorism : Terrorism1231 Words   |  5 Pages Terrorism is a common term used in the media and news everyday, especially in the United States. We are in a constant battle against ‘terrorism’, â€Å"Counterterrorism has to be woven into the everyday workings of every department. It should be included on the agenda of every meeting†¦Ã¢â‚¬  (Kelling Bratton, 2006). Terrorism and How to Respond All terrorism is criminal but not all criminals are terrorists. Terrorism unlike most crimes has a political agenda behind it. Many terrorists are involved withRead MoreTerrorism : Terrorism And Terrorism851 Words   |  4 PagesTerrorist attacks are major threats that could occur in any nation. Terrorism is one of those things that can happen at any time. It will strike in small, medium and large cities. Although we will never be able to remove all risk from terrorism, we can definitely reduce the risk through hazard mitigation and disaster preparedness (GBRA, 2011). To better understand terrorism we need to know what it is. Terrorism can be defined as the use of force or violence against persons or property in violationRead MoreTerrorism : Terrorism And Terrorism1377 Words   |  6 PagesTerrorism in Sudan In the past, Sudan had been designated as a State Sponsor of Terrorism regarding support for international terrorist groups. However, Sudan has changed its approach ever since the 9/11 attacks has been aiding the United States in diminishing the pervasiveness of terrorist groups in Sudan, and in the world. Recently, Sudan has remained cooperative with the United States in its war on counter terrorism. Sudan has taken many preventive measures to keep these terrorist groups outRead MoreThe Effects Of Terrorism On Terrorism And Terrorism944 Words   |  4 PagesEffects of Terrorism â€Å"The history of terrorism is a history of well-known and historically significant individuals, entities, and incidents associated, whether rightly or wrongly, with terrorism,† (History of Terrorism). The history of terrorism is a long bloody road. One of the bloodiest of acts of terrorism in the early years, was the reign of terror. In which, the Jacobin leader, Maximilien Robespierre, executed 40,000 people. Newspapers coined the word â€Å"Terrorism† as a way of describing RobespierreRead MoreTerrorism Between Terrorism And Terrorism1207 Words   |  5 PagesQuestion † What trends are evident in terrorism over the past 5 years? How have these trends impacted on the ways in which counter terrorism has responded in the Australian context? Introduction Terrorism poses a serious security challenge to the Australia and globally as it prevalence has increased over a decade although less attacks occur in the Western nations. The purpose of this assignment is to examine what trends and terrorist tactics are evident internationally over the past 5 years andRead MoreTerrorism Between Terrorism And Terrorism2012 Words   |  9 PagesTerrorism has played a brutal and alarming role in societies across the world. Many nations have been confronted with the need to develop solutions in the wake of tragedies caused by terrorism. Unfortunately, terrorist organizations are still operating and terrorist acts have continued. Many questions that have still gone unanswered despite careful study, but governments are finding some relief when collaborating with anti-terrorism organizations (Fischer, 2002). Terrorists have struck almost everywhere

Tuesday, May 5, 2020

Decolonization of Algeria and Mozambique free essay sample

Decolonization of Algeria and Mozambique Essay Preparation Draft Today, Algeria and Mozambique are independent countries in Africa, but before that, since the early 1900’s and earlier, both countries were under colonial rule. Before Algeria and Mozambique gained their independence as a country, Algeria was under the French rule, while Mozambique was under Portuguese rule. However, eventually in 1962, Algeria gained its independence and in 1974 Mozambique gained its independence. In terms of the process of decolonization, Algeria and Mozambique went through a similar process, that was successful due to the failures of the colonial powers to satisfy and control their settler population socially, economically and politically, which resulted into successful organized rebellion actions. Referring back to the pre-call for independence, the Algerians and Mozambique settler population felt that they were being mistreated by their colonial power. In Algeria even since 1942, according to the West Chester University, the French were mistreating the Algerians by taking over â€Å"French-owned† farms and forcing the Algerian ex workers to work for them. We will write a custom essay sample on Decolonization of Algeria and Mozambique or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page At the end of WW2, the Vichy French government increased taxes, specifically for the Algerians and implemented â€Å"racial policies†, that favored the French. Similarly, Mozambique’s were discriminated, as the Portuguese deprived with lack of education, lack of political justification and very â€Å"cheap wages†. Despite both Algeria and Mozambique being treated unfairly socially, economically and politically, on May 8, 1945, the Algerians celebrated the end of WW2, by marching in Setif, but the Algerians raised â€Å"the green and white flag† of Abd al Kader’s 1840 uprising, which angered the French, causing violence and resulting in 45,000 deaths. Being unfairly treated, the Algerians and Mozambique’s called for independence. Algeria and Mozambique’s call and war for independence were a result of creating large organized rebellion groups, however, each country’s political aim was different. As for Algeria, on October 1952, Ahmen Ben Bella an Algerian rebellious soldier formed the Revolutionary Committee of Unity and Action, which was later known as the National Liberation Front (FLN) on 1962. The FLN was responsible for the â€Å"political direction of the revolution. † The sole purpose of the FLN was to â€Å"acquire arms, supplies, and funds† for the commanders and gain independence. Similarly, on June 1962, the Mozambique formed the FRELIMO liberation movement, which was lead by Eduardo Mondlane. Unlike Algeria, FRELIMO was vastly supported by â€Å"communist† nations, primarily Soviet Union, East Germany and Cuba by receiving military aid, such as â€Å"shipments of 122mm artillery rockets in 1972. † Therefore, during the war for independence in Mozambique, was a cold war element, in which the communist nations saw Mozambique as an opening to advocate communism spread. Hence, Mozambique was disrupted by other nation’s political aims efforts of anti-imperialist, towards spreading communism. Through the war for independence, Algeria and Mozambique would eventually gained independence. At the end, Algeria and Mozambique gained independence, however each country’s colonial efforts of letting go, was different. Speaking of Algeria, the war for independence lasted from 1953 to 1962, about 9 years. On the other hand, Mozambique lasted from 1962 to 1974, about 12 years. Algeria gained independence, as the FLN was too powerful and resulted in â€Å"hundreds of thousands of deaths. † It was reported that, â€Å"kidnapping was a common place† as there were murders of captured French and Muslims, regardless of age and sex. Portugal at the same time tired to hold on with military efforts, as troop numbers rose to 24,000 and more. Differently, Portugal from the 1960’s to 1970’s attempted to counter the FRELIMO with the use of government propaganda by creating â€Å"roads, railways, bridges, dams, irrigation systems, schools, hospitals. † However in the end, on July 1962 Algeria gained independence, with 350,000 colons leaving the country and 1. 4 million more the next year and counting. Meanwhile, on June 1975, Portuguese handed over the power to the FRELIMO. In conclusion, Algeria and Mozambique were both very similar to the process of decolonization, as both countries’ settler population was unsatisfied by the treatment that they’re colonial power, socially, economically and politically. Reflecting back, the most common similarity that both countries had was the creation of large rebellion groups to overpower the colonial power, which were both successful, despite the violence. Therefore, the overarching reason why both countries lost their colonial power was because of their actions.

Wednesday, April 8, 2020

Waiting For Godot Essay Example For Students

Waiting For Godot Essay Waiting for Godot has been a subject of my thoughts for about two weeks now. While considering the work, its author, and the comments I have found about the play, I have come up with three hypotheses as to the meaning and overall theme. Either it is about Humanity waiting for a savior that does exist to return; or it could be about the hopelessness of Humanity waiting for a savior that doesn’t exist, and therefore will never come; or, the easiest of possibilities, that Waiting really has no theme at all. This last theory is the one that I most readily accept, and the answer that Samuel Beckett, the author of the play, put forth when questioned about the meaning of his strange little piece. We will write a custom essay on Waiting For Godot specifically for you for only $16.38 $13.9/page Order now Many critics put the first theory forth as the true meaning of Waiting, and there are many aspects of it by which they can make their point. The most obvious is the title character, Godot, because the root word of the name is God. The many references to Christianity also create a close connection between the storyline and many important stories from the Bible. From the very beginning Vladimir and Estragon ponder their salvation, consider death, and draw a parallel between themselves and the two thieves that were crucified along with Jesus, according to the Gospels. Vladimir: †¦One of the thieves was saved. It’s a reasonable percentage. Gogo. Estragon: What? Vladimir: Suppose we repented. Estragon: Repented what? Vladimir: Oh†¦we wouldn’t have to go into the details. Estragon: Our being born? The general attitude expressed throughout is the hopelessness, or possibly the meaningless-ness of life. Humanity’s purpose is simply to wait out its existence until the Second Coming. Everything we do, say, feel, experience, etc., is just passing the time until our lives come to an end. Vladimir: That passed the time. Estragon: It would have passed in any case. Vladimir: Yes, but not so rapidly. Let us assume that Godot does symbolize God. He is someone who will come to make a great change in the Vladimir and Estragon’s lives, a great change for the better. But Godot, and whatever that change may be, does not come throughout the length of the play. They mistake Pozzo for Godot, and they mistake the messenger for Godot, because they do not know what Godot looks like or what manner of person he may be. Likewise, through our lives we mistake people and occurrences for Christ. And that helps us to pass the time until we die. The fact that Godot never comes also helps to prove the second theory about the meaning of Waiting. What if God and the afterlife do not exist? What then? We spend our entire lives waiting, biding our time in anticipation of our great reward. But when our lives end, that’s it. All the preparation, all our good intentions, are useless and meaningless because there was no meaning in the first place. Beckett may have used the play to illustrate how pathetic Humanity seems as it strives toward a nonexistent goal. He also made great fun of all those philosophers that ponder on the meaning of our existence using the character of Lucky. When Lucky makes his lengthy oration of nonsense, it is illustrating what nonsense everything that all the great thinkers have said on the meaning of life. For if life has no meaning, then it is all gibberish, and Lucky makes just as much sense as Voltaire. The third and final theory about the meaning of Waiting for Godot is that it has no meaning. When questioned repeatedly on the matter, Beckett was quoted in the New York Times as saying, â€Å"I know no more of this play than anyone who manages to read it attentively,† and, †I do not know who Godot is. I do not even know if he exists.†

Monday, March 9, 2020

How to Write a STRONG Follow Up Email After Your Job Interview

How to Write a STRONG Follow Up Email After Your Job Interview After spending hours preparing for your job interview, the big day finally arrives. You go to your interview and all of your preparation has paid off. You ace it! You leave your interview feeling satisfied and confident. But you’re not quite finished yet. Even though you nailed your interview, someone else may have performed just as well. So how do you go above and beyond to differentiate yourself? You can’t just go home and watch reruns of Seinfeld. I mean, you can, but not before you perform one last crucial step. Send a follow up email after your job interview. According to  Whitney Purcell, associate director of Career Development at Susquehanna University, it’s vital to send a thank you email within 24 hours after your job interview. You should also make sure to send it during company business hours (obviously).But more importantly, Purcell goes on to say that sending a simple thank you note is not enough. Your follow up email needs to make you stand out f rom the crowd. You should highlight the best parts of the conversation you had, followed by a reminder as to why you are the best fit for the job.So the question becomes how do you write a strong follow up email after your job interview? According to  Dr. Deborah Good, an assistant professor at the University of Pittsburgh Katz School of Business, the email below is  ideal because it contains 6 very important characteristics:  Ã‚  Source: [BusinessInsider]

Friday, February 21, 2020

Fluride Varnish and how often general and pediatric dentist use them Essay

Fluride Varnish and how often general and pediatric dentist use them and how they feel about pediatricians applying them - Essay Example Health professionals, nevertheless, endorse prevention of oral diseases first to parents through proper oral hygiene for preventive purposes (Nowak, 2006). It has been noted among experts about the lack of information on what is the extent of damage on fluoride use to children (Moss, 2005). In fact, use of fluoride toothpaste is actually recommended during infanthood as soon as a substantial quantity of baby teeth have grown as part of the proper care for children's teeth, although it is also highly recommended that a pediatric dentist be sought for any necessary treatments such as the use of fluoride varnish (Jacobs, 2005). Starting in 1977 until 2003, the American Academy of Pediatric Dentistry or AAPD advocated the use of fluoride as "a safe and effective adjunct in reducing the risk of caries and reversing enamel demineralization," to the extent that AAPD encouraged public health officials, health care providers, parents and caregivers to "optimize fluoride exposure," (AAPD, 2003). Nevertheless, the "Policy on Use (cannot delete "Use" because it is the title of a policy!) of Fluoride" cautioned the use of topical fluoride-containing products to young children to prevent ingestion of excessive amounts of fluoride (Warren & Levy, 1999). Fluoride varnish is considered as one of the breakthrough innovations in dentistry. The simple coating of fluoride treatment can provide long-term dental relief. Accordingly, fluoride varnish has higher concentration of fluoride compared with other forms of dental enhancements. Fluoride varnish is less toxic and provides no harm to children. According to Autio (2000), fluoride varnish quickly adheres to teeth and it takes less time than other topical treatment to be released to the tooth surface nurturing the minerals in the teeth. Toxicity has been a major concern with fluoride treatment especially among children ages 6 and below. In previous studies, it has been proven that fluoride varnish has the lowest rate of fluoride in the blood plasma compared with other topical treatments making it a safer choice for children (Moss, 2005). The use of fluoride varnish has been commonly seen in Europe. Also, the commercialization of fluoride varnish has become a crucial component of its introduction to other locations such as the United States, and some parts of Asia. Most important, the efficacy of fluoride varnish has been widely recognized (Moss, 2005). Fluoride varnish is a liquid coating that is applied to the teeth using a brush. The liquid dries quickly minutes after the application. Fluoride varnish provides a protective coating of fluoride on teeth. According to studies (Moss 2005 and Autio, 2000). The fluoride is released over a period of months that strengthens teeth and prevents tooth decay. The fluoride varnish needs to be reapplied every 3-4 months to maintain its effectiveness. This tasteless liquid has been used in several dental clinics. It has also been proven to be effective in preventing tooth decay and other related dental problems (Autio, 2000 and Moss, 2005). Fluoride varnish is safe as approved by the American Dental Association (ADA). After the fluoride varnish is