Physical properties of transparent optical polymers Dissertation

Physical properties of transparent optical polymers - Dissertation Example substituted ethylenic) copolymer (Weber, 2003). Structural units of most of these polymers are given in the figure 5.2. Fig. 5.2: Structural units of common optical polymers (Martienssen and Warlimont, 2006). Because of the variations in structure, the properties such as refractive index, thermal stability, etc. vary among the different polymers (Losch et al., 1992). The properties of certain optical polymers (PC, PMMA, and ADC in comparison to glass are shown in figure 5.3. Fig. 5.3: Comparison of physical properties of glass and optical polymeric plastics – PC, PMMA and ADC (Optical Polymers International, 2010). This chapter describes and compares the physical properties of common optical polymers. The following physical properties will be discussed further: 1. ... The scattering loss of these materials is low and their refractive indices are controllable (Jones, 1997). This allows their fabrication into waveguide structures. 5.2.1. Comparison of Refractive Index The refractive index of most transparent polymeric materials is around 1.5. As these are carbon based, their refractive indices and dispersion are very different from crystals and glasses (Weber, 2003). Polyetherimide (PEI) has a refractive index higher than most other optical polymers. Other polymers with high refractive indices include polyarylsulfone, polyarylate, PC, and PS. PMMA has a refractive index of 1.491. The refractive indices of some common polymers are shown in table 5.1. The refractive index of ADC is 1.50, which compares well with that of glass. Polymer Refractive index PEI 1.658 Polyarylsulfone 1.651 Polyarylate 1.61 PS 1.590 PC 1.586 SAN 1.579 CR-39 1.504 PMMA 1.491 TPX 1.466 Table 5.1: Refractive indices of common polymeric materials. The refractive index of a polyme r is influenced by the polarizability, free volume and the difference between the maximum absorption wavelength and optical wavelength of the material (Ma et al., 2002). The higher the density and the polarizability of the material, the higher will be its refractive index. Various other polymeric materials have been used in optical focusing mechanisms. These include polyimides (PI), fluoropolymers (FP) such as Tedlar ® PVF, Tefzel ® ETFE, and Teflon ® FEP, and hydrocarbon polymers (HCP) like polyvinylbutyral (PVB). Among the fluoropolymers, the lowest index of refraction is that of Teflon FEP, which is completely fluorinated (French et al., 2011). It is observed that as the amount of

Nobody Gets Married Anymore, Mister by Gerry Garibaldi Article

Nobody Gets Married Anymore, Mister by Gerry Garibaldi - Article Example The author predicts in the article that although money, reforms, and the gleaming porcelain hold great importance for the schools they can hardly make a good impact on the minds of the children. The reason is that urban teachers and students are facing such problems, which are associated with the mindset of children, which cannot be changed due to reforms. â€Å"Urban teachers face an intractable problem, one that we cannot spend or even teach our way out of teen pregnancy†. In the remaining part of the article, the author describes her experience of dealing with her pregnant students. The author mainly emphasizes her encounter with a girl named Nicole who is likely to become a teenage mother. Along with Nicole, who has been the focus of the author in the whole article, the author also highlights her experience with another student, jasmine, who gave birth to a child nearly six months ago. In the end, the author tells us about Data Wall, which is a strategy for the teachers to produce data about the progress of the students. My own belief about the issue of teenage pregnancies is somewhat conservative. I believe that teenage pregnancies result in creating many social and health problems. The government of the U.S.A provides considerable benefits to the unwed teenage mothers, which is one of the main factors behind the increase in the rate of teenage pregnancies. Jansson states, â€Å"Refusing or severely limiting public benefits to teenage mothers, will reduce out-of-wedlock birthrates†. Some girls do not get pregnant intentionally. Such girls forget using pills or other contraceptive methods during sex, so their chances of getting a pregnant increase. Such pregnancies also give rise to illegal abortions, which is another ethical issue.

Assess 'Reformasi' and the democratic transition in Indonesia Essay

Assess 'Reformasi' and the democratic transition in Indonesia - Essay Example An assessment is made of the ideals and goals of Reformasi and how these compare with the present reality. The conclusion identifies key issues facing the country. Indonesia is a Southeast Asian archipelago of over 12,000 islands, with a total population of 270 million, making it one of the largest Islamic nations in the world (CIA, 2007). A Dutch colony for over 350 years, it gained independence in 1945 under Sukarno, a nationalist leader who established a parliamentary government with him as its first President. By 1959, the government was struggling to contain three challenging threats: Islamism, communism, and militarisation. Sukarno established a â€Å"Guided Democracy† characterised by military-backed authoritarian rule, a non-aligned foreign policy, and socialist anti-modern economic policies, all of which proved chaotic and difficult to manage (Smith, 1999). Due to growing threats to peace and stability, the army staged a coup d’etat in 1965 under the leadership of Army Minister Suharto, who justified it as the only way to protect the nation from communism. Sukarno was deposed and on house arrest until his death in 1970. In 1967, Suharto was declared President and ruled Indonesia until his resignation in May 1998, succeeded by his hand-picked successor, B.J. Habibie, who initiated the period of reform in Indonesian politics. During his short term, he allowed parliamentary elections, granted independence to East Timor, and in October 1999 handed the Presidency to Abdurrahman Wahid, who in July 2001 stepped down on charges of corruption and handed power to Megawati, Sukarno’s daughter. When her term ended in late 2004, Susilo Bambang Yudhoyono or SBY, a retired Army general who played a key role in 1998 became the country’s first democratically elected President (Soesastro et al., 2003; McGibbon, 2006). Indonesia’s recent history could be divided into three

The Patriarchal and Hierarchical Development of Western Civilization Research Paper

The Patriarchal and Hierarchical Development of Western Civilization - Research Paper Example The earliest human civilizations emerged in the great river deltas of the world, where the land was fertile, water was plentiful, and the rivers provided a means of easy transport. It was the ability to create food surpluses, store them and transport them around the local area that prompted early societies to give up a nomadic hunter gatherer lifestyle, and develop solid buildings for permanent residence. This created the leisure time for experimentation and the practical need for the development of technologies. In Mesopotamia the first writing tablets appear to have been made, and they record many lists and commercial details relating to the trade in basic goods. The famous Epic of Gilgamesh tells the story of a famous ruler who started out behaving badly towards his subjects, and particularly women. He has a lot of power, partly because of his status as heir to the throne of Uruk, but partly also because â€Å"Two thirds of him is god, one-third of him is human† (Tablet 1). He is descended from a goddess, and the story tells of his interactions with both human and godly characters. Goddesses play a big part in the plot, since it is the goddess Aruru who creates the special friend Enkidu for Gilgamesh, and the goddess Ishtar openly taunts him and tries to tempt him into a relationship with her. Gilgamesh is at the mercy of these divine figures, and they largely determine the course of his life. Gilgamesh refuses the advances of Ishtar, showing great strength of character, but in the course of the epic he comes to learn the lessons that his mother and the other goddesses have made every effort to teach him: love for others is of much greater worth than riches, fame and power. The power of the female to bring forth life, and the danger of amorous entanglements, remain key motifs in the story, and they serve to tame the faults of the male, and to counterbalance his arrogance and immaturity. The ruler Gilgamesh at the end of the epic reflects on the massiv e architecture of his city’s walls which encloses the well-ordered community that thrives under the care of the goddess Ishtar: â€Å"is not even (the core of) the brick structure of kiln-fired brick, †¦ one league city, one league palm gardens, one league lowlands, the open area of the Ishtar temple, three leagues, and the open area of Uruk it encloses† (tablet XI). The moral of the tale is that he finally accepts that he must settle down as an administrator in a settled urban community, rather than a wanderer in search of amorous or other adventure. In contrast to this the female characters in The Iliad, which dates from more than a thousand years later, are little more than goods to be passed from one powerful male hero to another, sometimes more or less willingly in matrimony, and sometimes as the spoils of war. In The Iliad notions of power are very much the main theme (Sherman, 2003, p. 47) The women like Helen of Troy are trophies, and their function is mor e symbolic than as an active participant in society. Homer stresses the heroic deeds of the warriors, and his western society values possessions, cities, and conquering other peoples. The patriarchal line of descent is stressed through the frequent repetition of lists of names and titles such as this: â€Å"After Diomede same the Atreidae/Agamemnon and Menelaus and then/the two named Aias, jacketed with brawn/then came Idomeneus and his

An Analysis on the Factors Affecting the Recent US Economic Growth Research Paper

An Analysis on the Factors Affecting the Recent US Economic Growth - Research Paper Example Since the degree of industrialization in the country is high, approximately 55% of its imports are crude oil (â€Å"The World Fact Book†). The economic prosperity of U.S. had declined to some extent during the oil price boom from 2001 to 2006 (â€Å"Recent U.S. Economic Growth†). The soaring prices of energy resources increased the cost of imports as well as industrialization in the nation. Moreover, the real estate sector of the nation was facing certain exuberances since the latter half of 2007 in U.S. (â€Å"The World Fact Book†). The real estate’s homes were traded for speculative purposes in the country. Over time, failure of some projects lead to severe crisis in the U.S. money market during 2008. The commercial banks were forced to offer to accept direct implicit bail outs and some of them like Lehman Brothers had collapsed due to severe financial crisis. The recession in 2008, had significantly lowered the economic growth of U.S. since the Great Depression. In order to set everything in the right state, the U.S. government in 2008 has decided to inject $700 billion in its market through the enactment of the Troubled Asset Relief Program (TARP) (â€Å"Recent U.S. Economic Growth†). Some of these funds were utilized by the state federal government for purchasing equities of banks and some industrial corporations. In addition to that in 2009, under the guidance of President Barack Obama, the Federal government injected an additional sum of $787 billion in the U.S. economy (â€Å"The World Fact Book†). It was claimed that this fund was supposed to be allotted for financing the expansionary fiscal policies of the country from 2010 to 2011. The federal budget defici t measured in terms of percentage change in GDP in U.S. was 9% in 2011 but it decreased to a level of 7.6% in 2012 (â€Å"The World Fact Book†). This proves that there are some substantial reasons for which the economic status of U.S. has

Taj Mahal Essay Example | Topics and Well Written Essays - 500 words

Taj Mahal - Essay Example The picture depicts the beautiful monument made of white marble, on the blue backdrop of the sky and the river, below! The Taj Mahal was built over a period ranging sixteen years, from 1632 to 1648, by the Mughal Emperor Shah Jahan, in the sweet remembrance of his wife, Mumtaz Mahal. It is essentially a mausoleum, built by the emperor, with love for his wife. Ever since, it has been the cynosure of tourists, architects and historians, alike. The first striking feature of this picture is the magnanimity of this mausoleum of love, contrasted against the miniature structure of humanity! We can see the huge graceful structure, against which the tourists and visitors look inconspicuous. This is what the monument delivers, with its beauty, which is a visual treat. The visitors and tourists possess expressions of awe and wonder, on viewing this magnificent building, which refuses not to cast a spell on anyone who visits or views it. Another striking feature of this monument is that the pure white marble used to build this monument is reflective of t

English Castle Essay Example for Free

English Castle Essay Castles are fortifications made to protect resources and lives as well. It is also the main structure of defense. Walls made of large well-defined heavy stones that are stacked to perfection. The castle has a stable, storehouse, bakeries, kitchens, cottages and quarters for soldiers. Usually a city a situated in a castle where a city is surrounded by walls and the only entrance is a single huge gate. This gate is where the merchants and entrepreneurs trade goods for the city market. It was the Norman conquerors who made the castle building an art. They built castles primarily as a defense outpost. They situate a castle in a high ground wherein it will be surrounded by water or a deep ditch. It was supposed to be high because it will delay intruders from attacking also it will be very susceptible for archers to snipe down intruders. Castle acts as keeps or strongholds that no one can penetrate. A castle is governed by a king, the highest rule. In the English setting, castles were built in Medieval era, wherein castles were made out of stone. This is a linear representation of what has transpired back then. In the Stone age, Causewayed Camps and Stonehenge was discovered. The Bronze age produced the Hillforts of England and the Maiden Castle, which is considered to be the biggest castle. In the Iron Age and the Romans Hillforts of England was reinforced since the English were under siege. The English people put up Hadrian’s Wall and the Roman Forts as a line of defense. After the Romans have fallen, the English people were restless with war and were attacked by Scotts, the Welch and the Anglo-Saxons. These invaders were also accompanied by the sudden attacks of the Vikings. By that time Alfred the great thought of defense mechanism to make England less susceptible for attacks. Alfred the great made the not a formation of walls instead made a strategic positioning of fortified towns that was called â€Å"Burhs†. Logically, if there are many fortified towns reinforcing each other then there will less attacks made because the chances of survival will be small. This happened in the reign of the Anglo-Saxon which is also known as the Dark Ages. But the root of all the prestigious castles made were from the Medieval Period spearheaded by the Norman Invasion in which they introduced the Motte and Bailey castle which is made from stone and wood. At this time, the Medieval Kings have devised a plan to erect Windsor and Warwick Castle. Then King Edward I conquered the Wales. He established the massive fortifications called Concentric Castles. Examples of these Concentric Castles are the Cowny, Harlech and the Caernarvon Castle. Concentric Castles were also called Edwardian Castles. They have no basic points of concentration. Their defense is the wall rings built around them and the entrance is a single gate that serves as bridge and also served as the gate. They lower the gates in the morning and closes at night. Castles in general are mainly for protection and also for economic purposes. There are estimated to be seventy-two English Castles and here are some of them: Alnwick, Lindisfarne, Warwick, Carisbrooke, Pevensey, Tintagel, Stafford, Pendennis, Lancaster, Herstmonceux, Saint Mawes, Grimsthorpe, Calshot, Rochester, Ludlow, Kenilworth, Richmond, Carlisle, Yarmouth, Bodiam and Scotney Castle. Among those numbers of Castle, a few stand-out such as Pontefract, Bodiam, Caister, Allington, Hever, Tower of London, Windsor, Warwick and Leeds Castle. Pontefract Castle was King Charles last fortress in the Civil War. Bodiam Castle was erected by a soldier in the time of King Edward III named Sir John Dalyngrudge. He believed that fortifying the castle would make it hard for intruders to penetrate. Caister Castle was built by Sir John Fastolfe, who fought in the French Wars. In the Allington Castle, Sir Thomas Wyatt was born. This castle was his sanctuary for writing the prose and verse of his poems. Hever Castle has a beautiful garden always been associated with Queen Anne Boleyn which is the concubine of King Henry VIII. The Tower of London is considered to be the royal residence of the King. It also means that it was the center of power. Tower of London is not a single tower but it consists of other different tower as defense structures. It thwarted the attacks of the Vikings. Beheading and tortures are also done here to show disillusion the people from the strength the government has and also to promote fear to their enemies. Windsor Castle is longest standing castle with its nine hundred years of its glorious existence. The Windsor Castle is comprised of three wards namely: Saint George’s Chapel as the lower ward, royal apartments and grad state rooms as the upper ward and middle ward is an amphitheater. The Warwick Castle follows a Motte and Bailey style that is made of wood but since the William the conqueror was in-charge the he changed the wooden part of the castle into stone by exploiting the Anglo-Saxon labor force. Lastly, the Leeds Castle, which lies on the River of Len and is strategically engineered between to adjacent islands. The name Leeds came from King Ethelbert IV called Ledian. Whatever the advantages of Motte and Bailey and Concetric designs, for being cheap and crude or tough and expensive, it sure made the history of England very meaningful. Acquisitions of land here and there entailed that there was a decentralized rule of power and due to it colonizers took advantage of it and waged war. The Norman conquerors should be proud on what they have achieved. Today, castles are just remnants of what has transpired back then. All of which is written in history, engraved in our memory. The hardships and sufferings of those who are tortured are screaming in the air where the castle stood. Ghosts of the dead haunt these sacred places, a place rich with tradition and full of honor and dignity. Castles are not just fortifications for protection but a shelter for the weak and oppressed, a symbol of bravery and diplomacy and above all a symbol of life in its borrowed existence. The English Castles are rich with memories of the executed and the times of triumph. For what of it remains is what is ours to preserve. Its existence can never be replaced, its value, its worth, and its beauty. Lastly, castles are not built by stone, wood or clay, it is made of the people’s blood, sweat and tears. People visit English castles because of awe and amazement that it brings to them. Its structure reminds them of how people have lived and it also depicts the events that have transpired back then. Since wars are the predominantly remembered association with castles, rumors and stories about the existence of ghosts emerged. The existence of ghosts is attributed to the executions done inside a castle and also to the prisoners kept in the dungeon. Though there is no material evidence to show that there are ghosts within these castles, people still insists its existence. The intricate designs and ornamentation around the castle adds up to the mysticism it brings to the visitors. The main attraction in visiting castles is the place where the throne is situated since in represents royalty and dominance over a large scale of people. But there is also an equal attracting part of the castle in contrast to the throne is the dungeon or lair. This is where prisoners of war are kept. In this place, it is believed that prisoners are being tortured to death to extract information from their army. Since, loyalty is valued, these prisoners are executed and their screams fill the air like a resonating sound of a ghost. Death is considered to be the ending of their torment. In sum, castles are visited based on their history and to what historical events have happened there. Castles best explain how the pre-existing people have lived their lives and also it show how technology have transcended to what it is right now. The scientific engineering and planning of creating a good castle is logically thought of. Every detail of a castle has a rational purpose. It was distinctively modified upon the needs of the people living in it. Lastly, the long-lasting castles are the evidences of the great historical events for the English people.