Intermediate accounting Essay Example for Free

Intermediate accounting Essay1. Distinguish between perpetual and periodic inventory dodge. wherefore conduct fleshly inventory? When should, if any a animal(prenominal) inventory count occur?Perpetual inventory system is a system for determine the cost of goods sold by keeping continuous records of the physical inventory as goods atomic number 18 bought and sold. In other words, under the perpetual inventory system records are kept of the quantity and usually the cost of individual items of inventory throughout the year, as items are bought and sold. The cost of goods sold is recorded as goods are transferred to customers, and the inventory balance is kept current throughout the year, as items are bought and sold. The physical inventory is important because it is an actual amount of all merchandise on hand at the end of an accounting period.The actual physical count of the product must occur after the Pre-Physical Inventory update is run. It means that no movements of th e product can occur until after the actual count is make. In other words the product is frozen until a physical count is done on the item. After the actual count the movement of the individual item within the product group can resume while other products are being count. In periodic inventory system, it is a system for determining the cost of goods sold by deducting the ending inventory (based on a physical count of the inventory) from the beginning inventory plus total purchases over the period.2. Intangible assets bring on two main characteristics. They lack physical existence and they are non financial instruments. Costs incurred internally to create intangibles are generally expensed as incurred. Explain the procedure for amortizing intangible assets.Intangible assets are a long-term assets that cause no physical substance but have a value based on rights or privileges that accrue to the owner. Intangible assetsdont have the obvious physical value of afactory or equipment th ey can prove very valuable for a firm and can be critical to its long-term achievement or failure. For example, a company such as Coca-Cola wouldnt be nearly assuccessful was it not for the high value obtained through its bulls eye-name recognition. Although brand recognition is not a physical asset you can see or touch, its positive effects on bottom-line profits can prove super valuable to firms such as Coca-Cola, whose brand strength drives global sales year after year.In FASB STATEMENT NO. 142, the useful purport of true intangible assets is difficult to judge, particularly assets that involve contracted or other legally set terms. Companies use the useful life of assets to guide their decisions on whether or not to amortize them on their financial statements.The key factor in determining whether to amortize an other intangible asset is its useful life. If it is indefinite, the asset is not amortized. Although the question of whether an assets useful life is definite or ind efinite may seem straightforward, certain intangiblesparticularly those that are a go forth of contracted or other legally set termsare difficult to judge. Prior to the issuance of FASB Statement no. 142, the maximum useful life of an intangible asset was 40 years. Could an asset a company was amortizing over a useful life of less than 40 years now have an indefinite life under Statement no. 142?The answer is maybe. Prior to its implementation companies may not have taken all of the three criteria in Statement no. 142renewability, costs and modificationsinto account in making amortization decisions. Further, it was not an option for an asset to have an indefinite useful life, regardless of how a company evaluated the criteria before Statement no. 142. The limit was 40 years. The bottom line? Even those intangibles that werent assigned the full 40-year useful life anterior to Statement no. 142 should be evaluated against the statements criteria. They may have indefinite useful live s as well.Referenceshttp//www.sdc.on.ca/sdc6/help/Physical%20Inventory%20Process.htmJennefer M. Mueller. Journal of Accountancy amortisation of Certain Intangible Assets.DECEMBER 2004 / Volume 198, Number 6.

Indian Removal Act Essay Example for Free

Indian Removal Act EssayKnown as having adopted an Indian child as his son, Andrew capital of Mississippi was quite fond of the Indian race however, with pressure to expand westward, he needed to transfer the Indians farther west and soon became their worst enemy. Andrew Jacksons Indian Policy was to drive the Indians westward as peacefully as possible, for the tribes that stayed in the East Coast were annihilated. Also, moving them West lead help them make love vaster, and there is a fair exchange for the tribes moving. Another important component is the gain of Western lands and the addition of American power this will add on to Americas size and increase Americas authority.Jackson validates his actions by saying he will pay for the land the Indians inhabit, pay for their long journey West, also known as the Trail of Tears, and support them a little while their settling in. President Jackson also said if they move west, they will enjoy sovereignty forever. Jackson made the point that with the Indians gone there will be less conflict between them and state governments, it will allow for prosperous populations and cities to flourish, and the free land will add another line of defense for America.President Jacksons attitude toward the Indians in his spoken language reveals that he wants the Indians gone so America can gain land and grow stronger. He uses words like Red Men and Savages to describe them, so they seem like outcasts. He makes it sounds like the Indians are a nuisance and if they move, they will prosper as a people. Jackson says, perhaps cause them stepwiseto cast off their savage habits and become an interesting, civilized, and Christian community. Overall, Jackson wants the Indians gone for his own benefit. He refers to them as uncivilized, uninteresting, and having savage habits, and was proving that he is just looking for a gain for his country, not the native people who have lived there forever.

Frank Wedekinds Lulu: An Analysis

blunt Wedekinds stunner An AnalysisDiscuss Frank Wedekinds hit in relation to its cultural and social context. Pay goicular attention to the ways in which the bend ch whollyenges and/or perpetuates certain assumptions concerning sex and intimateity take on a intelligence of the plays relevance to our contemporary context.This essay will be exploring and discussing the character of Lulu in Frank Wedekinds play of the analogous name. It will bowl everyplace into the relationship that Lulu has with the workforce and women of the late 1800s, as easily as the challenges that women have experienced over the centuries having to deny their sexual appetite in a patriarchal world. There will be investigations into female oppression and gender berth. Also one will be looking at the roles of fictional and genuine Femmes Fatales through start the ages, from those in story books to actual icons who have reached out to the world through modern media coverage. It will discuss whether creation a sexually sweet womanhood is help or hindrance, is a woman a slave to mens desires or is it a tool that women use to live and lead the life that they neediness?In research of the character of Lulu I read the introduction from the play Lulu adapted by Nicolas Wright and his insight to the character of Lulu and Frank Wedekinds method research by having sexual encounters with a number of prostitutes. Using this method Frank Wedekind created knockout, by taking disparate the qualities and flaws of the prostitutes he had met, women who are exposit as irresistible, some(a) fearlessly honest, some devious, some manic, all doomed. (Wedekind/Wright, 200711) Nicolas Wright gives the impression in the introduction thatCertainly he must have come crosswise a woman who, at the age of five or so, was raped and prostituted by a man who may have been her buzz off. This is exactly what had happened to Lulu, as Wedekind goes to some trouble to spell out. Is he saying that this hideo us event has formed her life, thats its made her what she is as an adult? As a 19th-centery buck, he may non spot the connection. Yet his comments on women are full of insight, and the way the way mantrap sexualises constantlyy relationship she enters into with a man seems very lots part of damaged- child syndrome.(Wedekind/Wright, 200711)By reading Nicolas Wrights thoughts on how the character of Lulu is an abused child and is a damaged soul and as a character has a very warped view of what is acceptable and what is normal in a relationship. Due to the impression of her childhood raised by a man who is give tongue to to be her father who is insinuated in the play they had an inappropriate relationship. This is apparent in Act 4. She asks Schigolch to kill Rodrigo (an acrobat who is blackmailing lulu) for her.Lulu what do you requisite? Dont ask too much.Schigolch well, now. if you ever felt nostalgic for our old arrangement..Lulu oh god..Schigolch Why non?Lulu Im .changed. I m not a child any more.Schigolch what do see when you look at me now? Some aged monster?Lulu but youve already got a mistress.(Wedekind/Wright, 2007 Act 494)Lulu from a young age was passed roughly like a toy for mens enjoyment. This information reflects that Lulu is always looking for someone to look after her, and the security which comes with marriage, as she has never had that as a child. Now as an adult Lulu pot only rely on her exceptional beauty and the event all men from different status are drawn to her. This in turn em springs her to command the men in her life, to bend to her every whim while the man still thinks he is in control. But in return by becoming what the man wants from her Lulu is able to enchant them by targeting their weaknesses and getting what she may want in that times before her eyes start to wonder again. This is more apparent when she marries for the second time, Eduard Schwarz. In this relationship she is the one who is control and she doesnt lik e this as she has nothing to manipulate him with, so it is my belief this is the reason she begins an affair with Dr Franz Schoning. This marriage to Schwarz seems to be a healthy relationship and very comfortable life style, and which by Lulu incoming into this affair with Schoning makes me wonder that Lulu is not wanting a loving family and the security of being married, she wants some danger and excitement to her life, and to me this selfish attitude which umpteen women from her background would kill for makes me think what does Lulu really want? Its apparent she needs the security of marriage which is what society expects of women in her status and situation. But this isnt what lulu wants she is a healthy sexed woman with a natural sexual appetite which unfortunately was acquittance against the society grain.Lulus character was ahead of the times as she was written in a time when women were repressed and had to attach for security. In a way that was most women in that era am bition was to marry well and above their station. In Pride and Prejudice by Jane Austin Mrs. Bennet was obsessed with finding maintains for her five daughters. The heroine of Pride of Prejudice Elizabeth Bennet is the complete reverse of Lulu. Whereas Elizabeth Bennet wants to marry for dearest, and disliked the idea of marrying just for security.When she was proposed by her cousin Mr Collins it takes him some time to understand that his aim is being rejected by Elizabeth, in that time was quiet unheard of to actually refuse a proposal.Your portion is unhappily so small that it will be in all likelihood undo the effects of you loveliness and amiable qualifications. As I must in that locationfore conclude that you are not serious in your rejection of me, I shall chuse to attribute it to your wish of increasing my love by suspense, according to the usual practice of elegant females.(Austin,1996106)Even Jane Austen herself in 1802 accepted a marriage proposal from Harris Bigg-With er, but she later changed her mind the next day. In all of her novels the heroine somehow ended in a suitable marriage with the man of their affections, yet she herself went on to becoming an old maid which was her choice but in this article it states thatAusten never felt she had been presented with adequate choices it was either get married or catch a governess or a teacher. (http//www.sexualfables.com/spinster.php).Harris Bigg-Wither who after her death read her books more closely in trying to understand her refusal of him and came to conclusion that marriage didnt interest her, because in her novels she didnt include sexual passion, and also she would only write about the prelude to marriage in a platonic way. So does this mean that Austen felt that sexual tension in a marriage would be the downfall of a relationship that started without it and that was based on affection? I feel that Austen a women of the early(a) 1800s who was expected to marry and was scared of sex and the complications that come with it, and thought marriage should be the product of two people in love and not a realistic and practical arrangement. She is quoted from a letter to her nieceAnything is to be preferred or endured rather than marrying without Affection, (http//www.sexualfables.com/spinster.php).So in the early 1800s Jane Austen was changing the way women behaved towards marriage that being an old maid was the only acceptable life style if one wasnt inclined to marry. But by not marrying sparked rumours in the 1990s that Austen was in situation a lesbian and that was the real reason she didnt marry. This theory hasnt be proved or disproved, I think its an insult to any women if they choose not to marry that they are assumed be a lesbian. Even in todays society women are targeted and frowned upon if they choose to have a career over starting a family, which in my opinion it is a mans ego that is being injured by not being needed.Frank Wedekind went a different way his play Lulu by making her of sorts a high class prostitute and giving Lulu the looks and the skills to manipulate the men she wanted to pursue. In my opinion the reason why Lulu was shocking for the time it was written in is because, it was common thought that men were driven by their sexual desires and women had none. If Lulu was a man this play would be called Casanova. If the lead was a male it wouldnt be as shocking as the world would have heard of the antics of Giacomo Girolamo Casanova de Seingalt who had died 1798 who was renowned for a sexual marauder of young women and a gambler. But Lulu wasnt a man but she was influenced by the men in her life, she tried to gain power by enslaving the men she wanted with her sexual desire. Another woman in fiction used the same skills in attain what information her pray had.Milady Clarick de pass from The Three Musketeersa novelbyAlexandre Dumas. Milady Clarick de Winter was a teenager forced to enter the convent, but when she gets there she f alls in love with a priest with who she escapes with. They leave the church with stolen property to computer storage their new life together, for which both of them get caught and were branded criminals with the fleur de liys. Then she appears in Athos village living with a man, and pretending to be his sister. When Athos, fell in love with her and married her. After some time together he finds the brand on her shoulder, saying she was a thief. Thinking she had married him only for his money which is not true, a heart-broken Athos tries to kill her by hanging her from a tree. But she survived. At the time the book is written, apparently it was acceptable to kill your wife if you found out she had committed a crime. Milady Clarick de Winter is a capable and beautiful spy, she is an example of a strong, independent woman with a tragic past, and filled with hate for men, she enjoys seduction and the destruction of men. The men she traps will provide her with support for a short perio d of time but will most likely to meet an previous(p) end if they learn of her past. Milady Clarick de Winter is remorseless for her countless crimes.In my opinion Lulu and Milady Clarick de Winter are femme fatales, and to achieve their hidden purpose, by using their effeminate assets such as beauty, charm, and sexual allure. Both seem to be victims, caught in a situation from which they cannot escape the connections between Milady Clarick de Winter and Lulu are spiritual having relationships ending in deadly consequences for the men they ensnare. Both Milady Clarick de Winter and Lulu have many names given or changed them through marriage. Dr Goll Lulus graduation exercise husband in the play is in discussion with Dr Franz Schoning on their preferences on what they like to call her.With all these men renaming her is it any wonder that no-one knows the real Lulu? Does lulu exist anymore? I feel that there is such a power in a name, and by changing that aspect of a psyche they no desireer exist. So by changing lulus name constantly she becomes a whole new person with a new personality over and over again, and is sculptured into whatever the man wants.Goll You see I call her Popsy.Schoning I thought Mignon suited her well.Goll Mignon? No, Popsys better, from my personal point of view. I have a weakness for the incomplete . . . the immature . . . the innocent child in need of fatherly protection.(Wedekind/Wright, 200718)In the case of Milady Clarick de Winter she had to change her name as Athos, her first husband whom she loved deeply thought she was dead after hanging her from a tree, and for her own protection she changed it when she married Lord De Winter. With all these name changes is there wonder that these women manipulate men for their own gain. When its the man who has the power to change their names a moulding them into their puppets or to force them to change their name for protection. In the process stripping them of whom there are and who they could have been.Does society put the pressure on women to behave a certain way still? In a culture that is obsessed with the celebrity and the morbid fantasy of when things go wrong trying to find the information because even in death we as a society still want more. Marilyn Monroe was a beauty with curves she was more than a 50s sex goddess. She dominated the age of movie stars to become the most illustrious woman of the 20th Century and still has a strong fan base growing 45 years after her death. She was born Norma Jeane Mortenson and never knew who her father and was baptized Norma Jeane Baker. Her mother was mentally ill and Norma Jeane had to spend most of her childhood in foster homes and orphanages until she moved in with family friend, but when she was 16 the family she was living with was going to move and couldnt take Norma Jeane with them. She had two options return to the orphanage or get married.So even in the 1940s girls without family had two choices the state or m arriage, she married a boy who she had been dating for 6 months. On being discovered by a photographer while helping towards the war effort in a factory, and from then on she became a model and Marilyn Monroe. But her marriage didnt survive her new found career. Then she soared to fame by landing film roles and various awards, but on the 5th august 1962 she died of a possible suicide. The events surrounding her death isthe most talked and debated conspiracy theories of the twentieth and twenty-first centuries. Many believe she was killed by aim of the Kennedys and this was the belief of her second husband Joe DiMaggio and he died convinced the Kennedys were to blame, in an article about a book of his life written by his long term lawyer and friend Morris Engelberg. DiMaggio is to of expressedThey murdered the one person I loved, DiMaggio confided to Mr Engelberg.(http//news.scotsman.com/marilynmonroe/Joe-DiMaggio-died-convinced-JFK.2401434.jp)These beliefs come from man who loved her very deeply and expressed that the men she was in a romantic relationship was the cause of her demise, and many of her fans believe that there are allot of unanswered questions connected with her death and I agree the hoi polloi there is too much information missing. She was at the mercy of very powerful men who wanted to keep her quiet and the scandal if she ever diverged in the information she knew. The allegations of the Kennedys being connected with her death has not been proved or disproved. Like Lulu, Marilyn Monroe was playing a very dangerous game by underestimating the power she had over men and the men in power. It is insinuated that Lulu was killed by Jack the Ripper an educated man who used his status to lure vulnerable prostitutes with his refinery and wealth, one the suspects was Prince Albert Victor, Duke of Clarence and Avondalehe was grandson of male monarch Victoria but this was neither proved or disproved. When doing my research the similarities between Lulu and Marilyn Monroe was very chilling both women were killed as the result of men, but for me the fact that Lulu is a fictional character based on the women Wedekind met on his sex romping with prostitutes and his character has so many similarities with the icon Monroe is disturbing that plight of women hasnt changed much in a hundred years and more.My aim in this essay was to Discuss Frank Wedekinds Lulu including the context and time it was written in, and if the female gender role has changed much in the time scale, by exploring other writers, and eventually looking at a modern day icon. I feel my discussion is in a very female point of view and Im sure that if this was written by a man it would have a very different angle and maybe I should have gotten a male opinion on the subject. Did Frank Wedekind write Lulu to shock society? Or to describe that women of the 1800s were restricted my gender and status through text. When Frank Wedekind wrote Lulu I think he knew it would be s hocking in his society as a sex tragedy but I dont think that knew that he had divulged so much into the way women were repressed by their gender and how certain sexual traumas can affect the way women as a gender enter a sexual relationship. Even today women use their sexual allure to get what they want or to influence a man into doing things for them. Im my opinion women have been fighting for the right to be equal with men but yet we as a sex still choose to use our beauty to get what we want and is that because from a young age society and story books use the stereotype of the woman is at home with the children and the man makes a living and supports his family. The times have changed and as a culture we have accepted same sex marriage, same sex adoption and a black president which I thought I would never see in my life time, but the life long battle of the sexes continues and I dont think this is going to end with any outcome which will be acceptable for either side. Lulu is a modern gambol of sex. Its not a helpful story about gender roles or sexual politics, or even at heart a marriage play, as all four of her marriages end badly. Lulu is a ruthless test of the terrible destructive would be of a basic human drive, and of that favourite whipping boy for that destruction, the femme fatale.BibliographyAusten.J (1996) Pride And Prejudice, London, Penguin Group.http//news.scotsman.com/marilynmonroe/Joe-DiMaggio-died-convinced-JFK.2401434.jphttp//www.sexualfables.com/spinster.phpWedekind.F/Wright.N (2007) Lulu, London Nick Hern Books limited.ResearchAscription of Identity The Bild motif and the character of Lulu, Silvio Jose Dos Santos, The Journal of Musicology, Vol. 21, No.2 (spring 2004), pp. 267-308http//www.marilynmonroe.com/Masterpieces of French literature By Marilyn S. SeversonRefraction of the effeminate The Monstrous Transformations of Lulu, Karin Littau, MLN, Vol. 110, No. 4, Comparative Literature Issue (Sept., 1995), pp. 888-912The Three Musket eersbyAlexandre Dumas

Biography of Chanakya (Kautilya)

Biography of Chanakya (Kautilya)INTRODUCTIONThe extraordinary thoroughness of Kautilyass work, its eminent inductiveness and practical character, its unflinching logic, heedlessness of adventitious lesson or religious standard and its wide range of subjects and interests gave it a unique combination of features..1-D.R.BhandarkarIn Indian history, the centuries to come and that passed by, ar recorded m any(prenominal) colossal someones and legendary characters who shaped time through their extraordinary deeds and their excellence in every skill. But among of them, Kautilya may be the only one record who has been respected and accepted as a brilliant person not only by Indian scholars but as well as western Scholars too. Kautilya was great political philosopher and thinker. We have been described as a great teacher, shrewd statesman, devoted patriot, deep thinker, ruthless administrator, master strategist, egoless ascetic, ideal philosopher and true saint.2 He is called all-aro und(prenominal) because he got mastery in all the branches of knowledge. He was well versed in commerce, warfare, Politics, Economics and Vedas. He lived around the third century B.C. but still today his ideas and principles show relevancy and applicability in the present day society. He is a historical milestone in the making of India. Kautilya is the greatest person with wisdom and knowledge. He is regarded pioneer in the field of Economics. The credit of establishment of Mauryan Empire goes to the foresight and knowledge of Kautilya. He was a key advisor and councilor of Chandragupta Maurya, the bring out of Mauryan Empire. This empire was not merely composed of a number of unrelated districts brought together under single sceptra it was a real unit based on common government which everywhere not only established the kings authority but the public good.3 Kautilya was chief architect of his rise to spot so he is called kingmaker too. A man full of vision he was always prepared for the worst. He had the guts to speak his heart out eventide in front of the rulers. He himself lived such a flavor, refusing all adornments, compassion towards the poor and evil to deceit when needed which shows some of his good characteristics of nature. Kautilya was a prof at the University of Takshashila which is located near Peshawar in Pakistan. He was the first man to envision the first Indian Empire by unification of the various down(p) kingdoms in the Indian subcontinent.His prominent works are Nitishastra, Chanakya Niti and Arthashastra. Among these, Arthshastra was most important. He considered economic activity as driving force behind the functioning of any political action. Kautilya was a true thinker who bridged the gap between knowledge and vision. For Kautilya, good governance was supreme.LIFE SKETCH OF KAUTILYA Unfortunately There is not certainity just about the time period of the Kautilya So, details of his birth and life are not dependable and we have to re ly on tradition. The expected period of the Kautilya is from 350-283 B.C.E. There are very few real historical facts about his birth and death except that he helped Chandragupta to mount the throne, to strengthen his empire and to unite theIndian states for engagement against Alexander of Macedonia around 327 B.C.E. Chandragupta Maurya established the Mauryan Empire in the year 321 B.C.E. Kautilya was probably born around 350 B.C.E. This shows that Kautilya was junior contemporary of Aristotle (384-322 B.C.E.). There is no proof that Kautilya was stirred by Aristotles idea. Some historians have questioning about Kautilyas existence. His place of birth is not assured. Some say that he got the pick up Chanakya because he was born in China. The Buddhist mentions his birthplace as Takshashila while Jaina scripture mention his birthplace as Chanak in Gola district of South India. correspond to one version, birthplace of Chanakya was Dravida so one of the Chanakyas various names was D ramila. Some believes his birthplace was Patliputra. However, Kautilyas birthplace will continue to remain a disputation. Kautilya had two other two names Chanaka and vishnugupta. As he was born in the village of chanaka, he was called chanakya , Dr. Ganapati Shastri is of the opinion that he was born in the kutala gotra. so he was named as Kautilya. His parents gave him the name of Vishnugupta at namkaran ceremony.4When Kautilya was born, he had blessed with the full set of teeth, which showed that child will become king or emperor.Rishi Chanak was a Kautilyas father who was learned Brahmin. He was a teacher teacher so he knew the importance of direction. He started teaching his son Kautilya in his early age.In his early age, Kautilya was well versed in Vedas though he memorized them completely at early age, At that ancient time, the Vedas were considered as the toughest scripture to study. He was also taught mathematics, geography and science along with religion. Right from hi s childhood, Kautilyas wisdom and shrewdness was visible and effective. His favorite subject was Politics. Kautilya had seen very difficult circumstances from his childhood. His father,Chanak was erudite, decent and self respected Brahmin. He opposed blemish or immortal deeds. The fraudulent and arrogant king Dhannanda did not like him naturally. The king disparated the rightness of Chanak so he harassed Chanaks family for fake reasons. Chanak was put in prison by the king. He died in prison. No one raised a voice against the injustice with Chanak. Kautilya was a very little boy that time. He was extremely sad because of his fathers death and injustice happened with his family. After his fathers death, his life was also in danger. So he left Patliputra by taking an oath that he would return and fight against injustice and gather in revenge against Dhannanda. Kautilya had his education at a famous university of Takshashila which was very reputed one at that time.Being a Brahmin of strong determination anf strong will, he thought to take revenge from Nanda King of Patliputra. He left the capital humiliated and he went to search for a warrior. On his way, he came across the young Chandragupta. He arrange in the latter a promising young man and started the campaign for his installation on the throne of Magadha. Their First attempt Proved to be a failure. However eventually, Chandragupta regrouped his forces, overwhelmed the borderstates and launched onslaught on the capital. The wicked king- Dhannanda best of Nanda dynasty wa skilled in 322BC. Thus a new dynasty-Maurya was established with Chandragupta Maurya enthroned as the king of Magadha in 321 BC and reigned upto 298 BC.The credit for this victory goes to kautilya widely accepted name whose diplomatic skill and encyclopaedic knowledge of administration enabled Chandragupta, his pupil not only to blessedness against the Nandas but also consolidate his empire.51 Vishnoo Bhagwan, Indian Political Thinkers,A tma Ram Sons publications,p.302 Retrieved from http//www.chanakya.com/chanakya.htm on 20 Mar.2014.11.28PM3 Paul Masson-Oursel et al Ancient India and Indian Civilization,p.374 Sankaracharya Commentary on Kamandaka5 Vishnoo Bhagwan, Indian Political Thinkers,Atma Ram Sons publications,p.31

Additive Manufacturing of Medical Implants: A Review

additive Manufacturing of Medical Implants A ReviewE. GordonWayne State University College of EngineeringAbstractanalogue manufacturing has numerous applications and is gaining interest in the bio aesculapian field. The quality of additively manufactured parts is constantly improving, which contri plainlyes to their increase use for medical infixs in patients. This paper reviews the literature on running(a) additive manufacturing applications use on patients, with a focus on the customization of 3D printed founds and the world power to incorporate scaffolds on the implant surface. Scholarly literature databases were apply to find brokerral in governance on the focus topics, as well as case studies of surgical applications of additive manufacturing implants in rodents and humans. The advantages of additive manufacturing medical implants intromit improved medical outcome, cost effectiveness, and reduced surgery time, as well as customization and incorporated scaffold. Over entir ely, the nigh effective type of additive manufacturing for the medical implant application is electron carry melting using Ti-6Al-4V because it rear end produce a high quality, high ingenuousness biocompatible implant that has the inevitable robotlike properties.Keywords Additive Manufacturing, Customized implants, Scaffold, 3D Printing, Ti-6Al-4VIntroductionIn recent years, additive manufacturing technologies digest improved pregnantly, thus expanding the fields and applications for which they can be apply. These 3D printing technologies create somatic models from digital models without the need for tool and die and process planning. Additive manufacturing can fabricate prototypes of complex shapes in a variety of materials such as metals, polymers, and nylon. metal components, in particular, can be used for practical applications such as medical implants devices manufactured to replace or support a biological structure. The biocompatibility of these auriferous devices must be considered, creating rigorous requirements for the material selection and final material properties of the structure. Studies be allow shown that additive manufacturing successfully produces implants with biocompatible materials that meet the structural requirements 1-6.3D printing medical implants can provide many benefits such as the customization and personalization of the implants, cost-effectiveness, increased productivity, and the ability to incorporate scaffold. Using custom made implants, fixtures and surgical tools can help lessen surgery time and patient recovery time, plot of ground increasing the likelihood of a successful surgery 7. An another(prenominal) benefit is the cost efficiency of 3D printing medial implants. Traditional manufacturing rules argon cheaper for large quantities, but ar much expensive for personalized designs and small production runs 8, 9. 3D printing is peculiarly cost effective for small-sized implants like spinal or dental implant s. 3D printing is also faster than traditional manufacturing if a custom implant inevitably to be made traditional regularitys require milling, forging, and a long delivery time while 3D printing may only take slightly a day 1. Another notable benefit of additive manufacturing is the ability to share data files of designs. Files saved as an .STL can be downloaded and printed anywhere in the world. The National Institutes of Health established a 3D Print Exchange to promote open-source sharing of 3D print files for medical models 7. The most significant benefits for the biomedical industry, however, are the ability to manufacture biocompatible materials, customize implants, and incorporate a porous scaffold surface.Types of Additive ManufacturingThe additive manufacturing approach uses computer software to solidus a complex 3D model into layers of 2D cross-sections with a minute onerousness. The layers are then printed layer by layer beting on the particular method chosen for the application. There are dozens of types of additive manufacturing systems on the market, some of the most common being stereolithography (SLA), direct metal laser sintering (DMLS), selective laser sintering (sodium lauryl sulphate), selective laser melting (SLM), 3D printing (3DP), and electron beam melting (EBM). These systems are classified according to the form of the raw material, which can be powder, liquid, or solid form 8. The deuce types of additive manufacturing that are most commonly used for medical implants are SLS and EBM.Figure 1 fulfil chain for SLM and EBM. The pre-processing before manufacturing includes 3D modeling, file preparation, and slicing of the 3D model into layers. Post-processing may include affectionateness treatment and polishing of assumed parts 10. discriminating Laser SinteringAn SLS printer uses a powder form of material for printing preys. A laser fuses a single layer of powder by drawing the shape of the object according to the first 2D cr oss-section of the 3D model. Immediately, the build platform is lowered by the defined layer thickness and another layer of powder is rolled across 10. The process repeats, fusing each layer one at a time to form the object. SLS can be used with metal, ceramic, and plastic powders. The precision of the laser and the diameter of the powder determines the degree of detail of the final object, so it is possible to create detailed structures with an SLS printer 11.Figure 2 Schematic of SLS system. The key components of SLM include the laser system (a fiber laser, F-theta and galvanometer used to overtop the laser beam movement) and the mechanical system (movable build platform and powder roller) 10.Electron Beam MeltingAn EBM printer uses a powder form of material for printing objects, similar to SLS. However, while SLS uses a laser to fuse each layer of the powder, EBM uses an electron beam. This energy is delivered th untrimmed an electric circuit between a tungsten strand inside of the electron gun and the build platform 10. An electric current heats the filament to emit a beam of electrons 1. Electric energy is transformed to heat energy which melts the powder on the build platform. The process continues similarly to SLS, where powder is spread across the platform in a thin layer, the cross-section of the object is melted, and then the build platform lowers by the layer thickness. A key element of EBM is that the build chamber is kept under vacuum, which allows the object to be produce great detail (70-100m) 1.Figure 3 Schematic of EBM system. The key components of EBM include an electron beam system (electron gun assembly, electron beam focusing electron lens and deflection coils used to control the electron beam) and the mechanical system (movable powder rake and fixed powder cassettes) 10.Materials of Medical ImplantsThe most common metals used for surgical implants are stainless steel 316L (ASTM F138), Cobalt ground alloys (ASTM F75 and ASTM F799) and titanium alloy Ti-6Al-4V (ASTM F67 and F136) 12, 13. However, these metals pay disadvantages such as the potential release of toxic ions and particles due to wearing that cause inflammation and allergic reactions, affecting biocompatibility 14. Also, the materials that have an elastic modulus that is not similar to natural bone stimulate new bone growth naughtily 12. Despite this, the low Youngs modulus, high strength, and nonlinear elasticity of titanium-based alloys make it the least harmful choice 3. The most commonly used titanium alloy is Ti-6Al-4V (Ti64) because it also has a better enemy to corrosion compared to stainless steels and cobalt-based alloys 15. Additive manufacturing has also been done using Tantalum. Tantalum is biocompatible, hard, ductile, and chemically resistant, but it is expensive and difficult to apparatus 6. Titanium based alloys are superior, thus Ti-6Al-V4 is the best material for additive manufacturing medical implants.MaterialYoungs modulus (GPa )Ultimate tensile strength (MPa)Yield strength (MPa)extension (%)TiTa75.77 4.04924.64 9.06882.77 19.6011.72 1.13Ti6Al4V131.51 16.401165.69 107.251055.59 63.636.10 2.57cpTi111.59 2.65703.05 16.22619.57 20.255.19 0.32Table 1 Tensile properties of SLS produced TiTa, Ti6Al4V and commercial-gradely pure titanium samples (n = 5) 16.Customized ImplantsAdditive manufacturing allows for the design and fabrication of customized prosthetic implants that are created to meet the specific needfully of a patient, such as the size, shape, and mechanical properties of the implant. Additive Manufacturing reduces design time as well as manufacturing time because the implant pattern is computer generated with CT and MRI scans, thus removing the need for a physical model 8. The ability to produce custom implants quickly solves a common problem with orthopedics where commonplace implants do not always fit the needs of certain patients. Previously, surgeons had to manually modify implants t o make them fit the patient 7. These techniques can be used by professionals in a variety of specialties such as neurosurgery, orthopedics, craniofacial and plastic surgery, oncology, and implant dentistry 8.One example of an application in which a customized implant is required is craniofacial re excogitationion. Craniofacial abnormalities are a diverse group of congenital defects that affect a large count of people and can be acquired at birth or due to injuries or tumors 8. Standard cranial implants seldom fit a patient precisely because skulls have irregular shapes 7. The custom implant can be created by using a CT scan to create a 3D virtual model of the patients skull. Then the model can be used with CAD software to design an implant that would perfectly fit the patient 8. Using custom implants has shown to improve the morphology for large and complex-shaped cranial abnormalities, and some researchers have observed a greater improvement in neurological functions than after s imilar surgeries using traditionally manufactured implants 17, 18.Figure 4 Skull model and customized implant for craniofacial reconstruction surgery 8.ScaffoldAdditive manufacturing medical implants allows the porosity of the surface to be designed, controlled, and interconnected, which provides better bone growth into implants, thus decreasing the chances of the body rejecting the implant. Additionally, the rough surface quality of 3D printed implants enhances bone-implant fixation 1. Without scaffold, there is a risk of bone weakening and bone loss around the implant, which is a consequence of puree shielding due to high stiffness of materials 19. The probability of this problem occurring is lessened when bone can grow into a porous surface of the implant 19.cellular lattice structures are classified by stochastic and non-stochastic geometries. The pores in stochastic structures have random variations in size and shape, while the pores in non-stochastic structures have repeatin g patterns of particular shapes and sizes 10. The main challenge in additively manufacturing scaffolds is the difficulty to remove the loose powder from within the pores, but an advantage is that additive manufacturing technology allows for the manufacturing of different types of scaffolds if a design requires it different regions of the implant could have different porosities 1, 10.The procedure used to achieve the porous areas with traditional manufacturing methods includes coating a smooth surface with other materials such as plasma-sprayed titanium or a titanium wire mesh however, combining different metals increases the risk of the body rejecting the implant. Additive manufacturing allows the smooth and porous surfaces to be fabricated with the same material, thus decreasing that risk. A variety of additive manufacturing techniques can be used to create the lattice structure, but scaffold can be fabricated by SLS or EBM without the need for support structures, thus reservation it the most effective method 5.Figure 5 Acetabular cup with designedFigure 6 (a) Porous femoral stem on the buildingporous surface 10.platform, (b) post-processed femoral stem 5.ConclusionThere are many advantages to using additive manufacturing to fabricate surgical implants. These benefits include improved medical outcome, cost effectiveness, reduced surgery time, as well as customization and scaffold. Overall, the most effective type of additive manufacturing for the medical implant application is Electron Beam Melting because it can produce a high quality, high purity biocompatible implant that has the required mechanical properties. The recommended metal to use for most implants is the titanium-based alloy Ti-6Al-4V because of its low Youngs modulus, high strength, nonlinear elasticity, and corrosion resistance. Overall, additive manufacturing is an excellent production method for medical implants because it allows surgeons to customize implants and scaffold to the specific ne eds of the patient.References1.Petrovic, V., et al., Additive manufacturing solutions for improved medical implants. 2012 INTECH Open Access Publisher.2.Ahn, Y.K., et al., Mechanical and microstructural characteristics of commercial purity titanium implants fabricated by electron-beam additive manufacturing. Materials Letters, 2017. 187 p. 64-67.3.Yan, L.M., et al., Improved mechanical properties of the new Ti-15Ta-xZr alloys fabricated by selective laser melting for biomedical application. Journal of all toldoys and Compounds, 2016. 688 p. 156-162.4.Caldarise, S., Hip joint prostheses and methods for manufacturing the same. 1996, Google Patents.5.Simoneau, C., et al., cultivation of a porous metallic femoral stem Design, manufacturing, simulation and mechanical testing. Materials Design, 2017. 114 p. 546-556.6.Wauthle, R., et al., Additively manufactured porous tantalum implants. Acta Biomaterialia, 2015. 14 p. 217-225.7.Ventola, C.L., Medical Applications for 3D Printing elect ric current and Projected Uses. Pharmacy and Therapeutics, 2014. 39(10) p. 704-711.8.Jardini, A.L., et al., Cranial reconstruction 3D biomodel and custom-built implant created using additive manufacturing. Journal of Cranio-Maxillofacial Surgery, 2014. 42(8) p. 1877-1884.9.DUrso, P.S., et al., Custom cranioplasty using stereolithography and acrylic. British Journal of waxy Surgery, 2000. 53(3) p. 200-204.10.Sing, S.L., et al., Laser and electronbeam powderbed additive manufacturing of metallic implants A review on processes, materials and designs. Journal of Orthopaedic Research, 2016. 34(3) p. 369-385.11.Hoy, M.B., 3D printing making things at the library. Med Ref Serv Q, 2013. 32(1) p. 94-9.12.Kokubo, T., et al., Bioactive metals preparation and properties. J Mater Sci Mater Med, 2004. 15(2) p. 99-107.13.Staiger, M.P., et al., Magnesium and its alloys as orthopedic biomaterials A review. Biomaterials, 2006. 27(9) p. 1728-1734.14.Polo-Corrales, L., M. Latorre-Esteves, and J.E. Ram irez-Vick, Scaffold Design for Bone Regeneration. Journal of nanoscience and nanotechnology, 2014. 14(1) p. 15-56.15.Dinda, G.P., L. Song, and J. Mazumder, prevarication of Ti-6Al-4V Scaffolds by Direct Metal Deposition. Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science, 2008. 39A(12) p. 2914-2922.16.Sing, S.L., W.Y. Yeong, and F.E. Wiria, Selective laser melting of titanium alloy with 50 wt% tantalum Microstructure and mechanical properties. Journal of Alloys and Compounds, 2016. 660 p. 461-470.17.Rotaru, H., et al., Cranioplasty With make Implants Analyzing the Cases of 10 Patients. Journal of Oral and Maxillofacial Surgery, 2012. 70(2) p. e169-e176.18.Agner, C., M. Dujovny, and M. Gaviria, Neurocognitive Assessment Before and after Cranioplasty. Acta Neurochirurgica, 2002. 144(10) p. 1033-1040.19.Shah, F.A., et al., Long-term osseointegration of 3D printed CoCr constructs with an interconnected open-pore architecture prepared by electron beam melting. Acta Biomaterialia, 2016. 36 p. 296-309.Bacillus Thuringiensis Distribution and HabitatBacillus Thuringiensis Distribution and HabitatLITERATURE REVIEWFor several decades since its discovery, formulations of Bacillus thuringiensis (B. t.) have been seen as the ideal nub of controlling Lepidoteran pests in agriculture because of the many attributes that differentiate this microbial insecticide from the synthetic chemical formulations. No toxicity to mammals, environmental friendliness, apparent immunity to the pesticide resistance phenomenon (no longer true), good integration with other pest control methods and the possibility of being mass produced at farm level at low cost, all made B. thuringiensis the much-needed tool for IPM programmes in developing countries. Research of almost 85 years reveals that Bacillus spp., especially B. thuringiensis and Bacillus sphaericus are the most potent biopesticides (Boucias Pendland, 1998). B. thuringiensis is a species of bacteria that has insecticidal properties that affects a specific range of insect vagabonds. There are at least 34 subspecies ofB. thuringiensis (also called serotypes or varieties) and possibly over 800 attain isolates (Swadener, 1994). B. thuringiensis accounts for about 5-8% of Bacillus spp. population in the environment (Hastowo et al., 1992). Till date more(prenominal) than 130 species of lepidopteran, dipteran and coleopteran insects are found to be controlled byB. thuringiensis (Dean, 1984).historic Background of B. thuringiensisB. thuringiensis are interesting and important bacteria used in the biological control of insect pest which form toxic watch crystal proteins at the time of sporulation. Perhaps the most well known and widely used biopesticide comes from B. thuringiensis, a bacterium that produces insecticidal proteins during its sporulation. This common soil bacterium, most abundantly found in grain dust from soil and other grain memory board facilities, was discovered f irst in Japan in 1901 by Ishawata and then in 1911 in Germany by Berliner (Baum et al., 1999). It was subsequently found that thousands of strains of B. thuringiensis exist (Lereclus, 1993). The bacterium was isolated from unhealthinessd larvae of Anagasta kuehniella, and this finding led to the establishment of B. thuringiensis as microbial insecticide.The first demean of its application to control insects was in Hungary at the end of 1920, and in Yugoslavia at the beginning of 1930s, it was applied to control the European corn borer (Lords, 2005). Sporine which was the first commercial product of B. thuringiensis was lendable in 1938 in France (Waiser, 1986) for the control of flour moth (Jacobs, 1951). Unfortunately, the product was used only for a very short time, due to World war II (Nester et al., 2002). Formation of transgenic plant was also observed. The first reports of insertion of genes encoding for B. thuringiensis delta-endotoxins into plants came in 1987 and the fi rst transgenic plants to express B. thuringiensis toxins were tobacco and tomato plants (van Frankenhuyzen, 1993). In 1957 pacific barm products commercialized the first strain on B. thuringiensis, named as Thuricide due to the increasing concern of biopesticide over the use of chemical insecticides.B. thuringiensis is a gram-positive spore-forming bacterium that produces vapourous proteins called deltaendotoxins during its stationary phase of growth (Schnepf et al., 1998). The crystal is released to the environment after analysis of the cell wall at the end of sporulation, and it can account for 20 to 30% of the dry weight of the sporulated cells (Schnepf et al., 1998)Distribution Habitat of B. thuringiensisThis bacterium is distributed worldwide (Martin Travers, 1989). The soil has been described as its main habitat however it has also been isolated from foliage, water, storage grains, and dead insects, etc (Iriarte Caballero, 2001). Isolation of strains from dead insects has been the main source for commercially used varieties, which include kurstaki, isolated from A. kuehniella israelensis, isolated from mosquitoes, and tenebrionis, isolated from Tenebrio monitor larvae (Ninfa Rosas, 2009 Iriarte Caballero, 2001).. The spores of B. thuringiensis persist in soil, and vegetive growth occurs when nutrients are available (DeLucca et al., 1981 Akiba, 1986 Ohba Aizawa, 1986 Travers et al., 1987 Martin Travers, 1989).DeLucca et al., (1981) found that B. thuringiensis represented between 0.5% and 0.005% of all Bacillus species isolated from soil samples in the USA. Martin Travers (1989) corned B. thuringiensis from soils globally. Meadows (1993) isolated B. thuringiensis from 785 of 1115 soil samples, and the dowery of samples that containedB. thuringiensis ranged from 56% in novel Zealand to 94% in samples from Asia and central and southern Africa. Ohba Aizawa (1986) isolated B. thuringiensis from 136 out of 189 soil samples in Japan.There are seve ral theories on the ecological niche filled by B. thuringiensis. Unlike most insect pathogenic microbes, B. thuringiensis generally recycle poorly and rarely cause natural epizootics in insects, leading to speculation that B. thuringiensis is essentially a soil micro-organism that possesses incidental insecticidal natural process (Martin Travers 1989). Evidence to support this view is that B. thuringiensis are commonly reported in the environment independent of insects and there is a lack of association between occurrence and insect activity (van Frankenhuyzen 1993). Meadows (1993) suggested quaternary possible explanations for the presence of B. thuringiensis in soil 1) rarely grows in soil but is deposited there by insects 2) may be infective to soil-dwelling insects (as yet undiscovered) 3) may grow in soil when nutrients are available and 4) an affinity with B. cereus.B. thuringiensis has been found extensively in the phylloplane. NumerousB. thuringiensis subspecies have been recovered from coniferous trees, deciduous trees and vegetables, as well as from other herbs (Smith Couche, 1991 Damgaard et al., 1997). B. thuringiensis deposited on the upper side of leaves (exposed to the sun) may remain effective for only 1-2 days, but B. thuringiensis on the underside of leaves (i.e. protected from the sun) may remain active for 7-10 days (Swadner, 1994).B. thuringiensis kurstaki has been recovered from rivers and public water distribution systems after an aerial application of Thuricide 16B (Ohana, 1987).Crystal Composition and MorphologyThe existence of parasporal inclusions in B. thuringiensis was first noted in 1915 (Berliner, 1915), but their protein composition was not delineated until the 1950s (Angus, 1954). Hannay (1953) detected the crystalline fine structure that is a property of most of the parasporal inclusions. B. thuringiensis subspecies can synthesize more than one inclusion, which may contain different ICPs (Hannay, 1953).Depending on their IC P composition, the crystals have various forms (bipyramidal, cuboidal, flat rhomboid, or a composite with two or more crystal types) (Bulla et al., 1977 Hfte Whiteley, 1989). A partial correlation between crystal morphology, ICP composition, and bioactivity against target insects has been established (Bulla et al., 1977 Hfte Whiteley, 1989 Lynch Baumann, 1985).Classification of B. thuringiensis subspeciesThe classification of B. thuringiensis subspecies based on the serological analysis of the flagella (H) antigens was introduced in the previous(predicate) 1960s (de Barjac Bonnefoi, 1962). This classification by serotype has been supplemented by morphological and biochemical criteria (de Barjac, 1981). Until 1977, only 13 B. thuringiensis subspecies had been described, and at that time all subspecies were toxic to Lepidopteran larvae only. The discovery of other subspecies toxic to Diptera (Goldberg Margalit, 1977) and Coleoptera (Krieg et al., 1983) enlarged the host range a nd markedly increased the number of subspecies. Up to the end of 1998, over 67 subspecies based on flagellar H-serovars had been identified.Genetics of ICPIn the early 1980s, it was established that most genes coding for the ICPs breathe on large transmissible plasmids, of which most are readily exchanged between strains by conjugation (Gonzlez Carlton, 1980 Gonzlez et al., 1981). Since these initial studies, numerous ICP genes have been cloned, sequenced and used to constructB. thuringiensis strains with novel insecticidal spectra (Hfte Whiteley, 1989).The currently known crystal (cry) gene types encode ICPs that are specific to either Lepidoptera (cryI), Diptera and Lepidoptera (cryII), Coleoptera (cryIII), Diptera (cryIV), or Coleoptera and Lepidoptera (cryV) (Hfte Whiteley, 1989). All ICPs described to date attack the insect gut upon ingestion. To date, each of the proteolytically activated ICP molecules with insecticidal activity has a variable C-terminal domain, which is r esponsible for receptrecognition (host susceptibility), and a conservedN-terminal domain, which induces pore brass (toxicity) (Li et al., 1991).Most naturally occurring B. thuringiensis strains contain ICPs active against a single order of insects. However, conjugative transfer between B. thuringiensis strains or related species can occur, resulting in new strains with various plasmid contents (Gonzlez Carlton, 1980). Thus the mobility of the cry genes and the exchange of plasmids may explain the diverse and complex activity spectra observed in B. thuringiensis (Gonzlez Carlton, 1980 Gonzlez et al., 1981 Gonzlez et al., 1982 Reddy et al., 1987 Jarrett Stephenson, 1990). New B. thuringiensis strains have been create by conjugation that is toxic to two insect orders.Nutritional billet of B. thuringiensisSince sporulation and germination in bacilli are dependent on the nutritional status of the organism (Hardwick Foster, 1952), a study of the nutritional requirement ofB. thuring iensis var. thuringiensis is important for delineating the control mechanisms which regulate spore and parasporal crystal formation. Certain amino acids support growth, sporulation and crystal formation of B. thuringiensis var. thuringiensis, while others inhibit the growth (Singer et al., 1966 Singer Rogoff, 1968 Bulla et al., 1975 Nickerson Bulla, 1975 Rajalakshmi Shethna, 1977). A lower concentration of cystine (Nickerson Bulla, 1975) or cysteine (Rajalakshmi Shethna, 1977) promotes growth, sporulation and crystal formation in . thuringiensis, while at a higher concentration of cys/cysSH, only the vegetative growth was observed, (Rajalakshmi Shethna, 1977).Classification of B. thuringiensisThe classification of B. thuringiensis subspecies based on the serological analysis of the flagella (H) antigens was introduced in the early 1960s (de Barjac Bonnefoi, 1962). This classification by serotype has been supplemented by morphological and biochemical criteria (de Barjac, 1981) . Many strains of B. thuringiensis have been isolated and classified within more than 20 different varieties by serological techniques. On the basis of their potency for insect these varieties have been grouped into five pathotypesLepidopteran-Specific (e.g. B. thuringiensis .var Kurstaki)Dipteran-Specific (e.g. B. thuringiensis . var israelensis)Coleopteran-Specific (e.g. B. thuringiensis .var. tenebrionis)Those active against Lepidoptera and Dipter(e.g. B. thuringiensis . var. aizawai)Those with no toxicity recorded in insects (e.g. B. thuringiensis . var. Dakota) way of ActionThe ICP structure and function have been reviewed in detail by Schnepf et al., (1998). Binding of the ICP to putative receptors is a major determinant of ICP specificity and the formation of pores in the midgut epithelial cells is a major mechanism of toxicity (Van Frankenhuyzen, 1993). After ingestion of B. thuringiensis by insect the crystal is dissolved in the insects alkaline gut. Then the digestive enzy mes that are present in insects body break down the crystal structure and activate B. thuringiensiss insecticidal component, called the delta-endotoxin (Swadner, 1994). The delta-endotoxin binds to the cells lining the midgut membrane and creates pores in the membrane, upsetting the guts ion balance. The insect briefly stops feeding and starves to death (Gill et al., 1992).Target OrganismsIn the past decades, B. thuringiensis Cry toxins were classified according to the target pest they attacked (Hofte Whiteley, 1998) however, due to the dual toxic activity exhibited by some cry genes and the inconsistencies in the original classification proposed by Hfte and Whiteley(1998), Crickmore et al., (1998) proposed a revision of the nomenclature for insecticidal crystal proteins, based on the ability of a crystal protein to exhibit some experimentally verifiable toxic effect in a target organism (Crickmore et al., 1998 Hfte Whiteley, 1998). The diversity of B. thuringiensis is exhibit i n the almost 70 serotypes and the 92 subspecies described to date (Galan-Wong et al., 2006).It is well known that many insects are susceptible to the toxic activity ofB. thuringiensis among them, lepidopterans have been exceptionally well studied, and many toxins have shown activity against them (Jarret Stephens., 1990 Sefinejad et al., 2008). Order Lepidoptera encompasses the majority of susceptible species belonging to agriculturally important families such as Cossidae, Gelechiidae, Lymantriidae, Noctuidae, Pieridae, Pyralidae, Thaumetopoetidae, Tortricidae, and Yponomeutidae (Iriarte Caballero, 2001).General patterns of use technical applications of B. thuringiensis have been directed mainly against lepidopteran pests of agricultural and forest crops however, in recent years strains active against coleopteran pests have also been marketed (Tomlin, 1997). Strains of B. thuringiensis kurstaki active against dipteran vectors of parasitic disease organisms have been used in public health programmes (Tomlin, 1997).Applications in agriculture and forestryCommercial use of B. thuringiensis on agricultural and forest crops dates back nearly30 years, when it became available in France (Van Frankenhuyzen, 1993). Use ofB. thuringiensis has increased greatly in recent years and the number of companies with a commercial interest in B. thuringiensis products has increased from four in 1980 to at least 18 (Van Frankenhuyzen, 1993). Several commercial B. thuringiensis products withB. thuringiensis aizawai, B. thuringiensis kuehniella or B. thuringiensis tenebrionise have been applied to crops using conventional spraying technology. Various formulations have been used on major crops such as cotton, maize, soybeans, potatoes, tomatoes, various crop trees and stored grains. Formulations have ranged from ultralow-volume oil to high-volume, wettable powder and aqueous suspensions (Tomlin, 1997). In the main, naturally occurring B. thuringiensis strains have been used, but tra nsgenic microorganisms expressing B. thuringiensis toxins have been developed by conjugation and by genetic manipulation, and in some cases, these have reached the commercial market (Carlton et al., 1990). These modified organisms have been developed in order to increase host range, prolong field activity or improve delivery of toxins to target organisms. For example, the coleopteran-active cryIIIA gene has been transferred to a lepidopteran-active B. thuringiensis kuehniella (Carlton et al., 1990). A plasmid bearing an ICP gene has been transferred from B. thuringiensis to a non-pathogenic leaf-colonizing isolate of Pseudomonas fluorescens fixation of the transgenic cells produces ICP contained within a membrane which prolongs persistence (Gelernter, 1990).Applications in vector controlB. thuringiensis Kurstaki has been used to control both mosquitos and blackflies in large-scale programmes (Lacey et al., 1982 Chilcott et al., 1983 Car, 1984 Car de Moor, 1984 Cibulsky Fusco, 1987 Becker Margalit, 1993 Bernhard Utz, 1993). For example, in Germany 23 tonnes of B. thuringiensis Kurstaki wettable powder and 19 000 litres of liquid concentrate were used to control mosquitos (Anopheles and Culex species) between 1981 and 1991 in the Upper Rhine vale (Becker Margalit, 1993). In China, approximately 10 tonnes of B. thuringiensis Kurstaki have been used in recent years to control the malarial vector, Anopheles sinensis.Resistance of Insect PopulationsA number of insect populations of several different species with different levels of resistance to B. thuringiensis have been obtained by laboratory selection experiments during the last 15 years (Schnepf et al., 1998). The species include Plodia interpunctella, Cadra cautella, Leptinotarsa decemlineata, Chrysomela scripta, Tricholplusia ni, genus Spodoptera littoralis, Spodoptera exigua, Heliothis virescens, Ostrinia nubilalis and Culex quinquefasciatus (Schnepf et al., 1998). The Indian meal moth, a pest of grain s torage areas, was the first insect to develop resistance to B. thuringiensis. Kurstaki (Swadner, 1994).Resistance progresses more quickly in laboratory experiments than under field conditions due to higher selection pressure in the laboratory (Tabashnik, 1991). No indications of insect resistance to B .thuringiensis were observed in the field, until the development of resistance was ob-served in the diamondback moth in crops where B. thuringiensis had been used repeatedly. Since then, resistance has been observed in the laboratory in the tobacco budworm, the atomic number 27 potato beetle and other insect species (McGaughey, 1992)B. thuringiensiss Ecological ImpactsSome of the most serious concerns about widespread use of B. thuringiensis as a pest control technique come from the effects it can have on animals other than the pest targeted for control. All B. thuringiensis products can kill organisms other than their intended targets. In turn, the animals that depend on these organi sms for food are also impacted (Swadner, 1994).Effect on Beneficial insectsMany insects are not pests, and any pest management technique needs to be especially concerned about those that are called rights, the insects that feed or prey on pest species (Swadner, 1994). B. thuringiensis has impacts on a number of undecomposed species. For example, studies of a wasp that is a parasite of the meal moth (Plodia interpunctella) found that treatment with B. thuringiensis reduced the number of eggs produced by the parasitic wasp, and the percentage of those eggs that hatched (Salama, 1993). Production and hatchability of eggs of a predatory bug were also decreased (Salama, 1991).Other insectsMany insects that do not have as directly beneficial importance to agriculture are important in the function and structure of ecosystems. A variety of studies have shown that B. thuringiensis applications can disturb insect communities (Swadner, 1994). Research pursuance large-scale B. thuringiensis applications to kill gypsy moth larvae in Lane County, Oregon, found that the number of oak-feeding caterpillar species was reduced for three years following spraying, and the number of caterpillars was reduced for two years (Miller, 1990).BirdsBecause many birds feed on the caterpillars and other insects affected by B. thuringiensis applications, it is not surprising that impacts of B. thuringiensis spraying on birds have been documented (Swadner, 1994). In New Hampshire, when B. thuringiensis-treatment reduced caterpillar abundance, black-throated blue warblers made fewer nesting attempts and also brought fewer caterpillars to their nestlings (Rodenhouse, 1992).Effects on HumansEight human volunteers ingested 1 gram of a B. thuringiensis kuehniella formulation(3 - 109 spores/g of powder) daily for 5 days. Of the eight volunteers, five also inhaled 100 mg of the B. thuringiensis kuehniella powder daily for five days. Comprehensive medical examinations in a flash before, after, an d 4 to 5 weeks later failed to demonstrate any adverse health effects, and all the blood chemistry and urinalysis tests were negative (Fisher Rosner, 1959).Pivovarov et al., (1977) reported that ingestion of foods begrime withB. thuringiensis gastroenteitis at concentrations of 105 to 109 cells/g caused nausea, vomiting, diarrhoea and tenesmus, colic-like pains in the abdomen, and fever in three of the four volunteers studied. The toxicity of the B. thuringiensis gastroenteritis strain may have been due to beta-exotoxin (Ray, 1990).In a purified form, some of the proteins produced by B. thuringiensis are acutely toxic to mammals. However, in their natural form, acute toxicity of commonly-usedB. thuringiensis varieties is limited to caterpillars, mosquito larvae, and beetle larvae (Swadner, 1994). special Concerns about B. thuringiensis ToxicityThe earliest tests done regarding B. thuringiensiss toxicity were conducted using B. thuringiensis var. thuringiensis, a B. thuringiensis s train known to contain a second toxin called beta-exotoxin (Swadner, 1994). The beta-exotoxin is toxic to vertebrates, with an LD 50 (median deadly dose the dose that kills 50 percent of a population of test animals) of 13-18 milligrams per kilogram of body weight (mg/kg) in mice when injected into the abdomen. An oral dose of 200 mg/kg per day killed mice after eight days (swadner, 1994) Beta-exotoxin also causes genetic damage to human blood cells (Meretoja, 1977).

Animal Farm as a Fable Essay -- Animal Farm

Animal Farm as a Fable   Traditional fables are clean stories that usually feature animals. Aesops Fables, which are probably the most well known, tell tales about animals that have clearly human characteristics, like the sly fox, the patient shoot a line and the selfish dog. Since Aesops stories have been told for over 2,500 years, they are clearly a form well suited to telling a universal truth in a way that is accessible to children and memorable for adults. In writing Animal Farm, Orwell wanted to express a particular set of ideas about revolutions - ideas that he thought were to a greater extent or less universal. The success of the book since its publication would seem to indicate that he had the right idea.   The plot of Animal Farm is clearly based on the events of the Russian Revolution. Old Majors ideas about animalism correspond to those of Karl Marx, and the way in which they are taken up and put into action represents the activities of Leon Trotsky (Snowball) and a combination of Lenin and Stalin (Napoleon). The indiscriminately nature of the rebellion closely parallels the opportunistic response to events that brought the Bolsheviks to power in 1917, and the history of the farm roughly follows events in European history up to the endorse World War. The fact that we are still reading Animal Farm recollective after these events have passed into history again suggests something of Orwells achievement.   The fable format allowed Orwell to wince complicated events to a level that almost anyone could understand - the workings of the Russian Politburo or of the NKVD (the secret police) are complex matters tho the story of Squealer and Napoleons teach dogs is much more accessible. Similarly, the lives an... ...such as when he speaks of Squealer, who had unaccountably been absent during the fighting. Again, young readers are likely to enjoy this kind of statement where the real meaning is that slightly below the surface.   Fables are meant to have a moral, and the moral of Animal Farm is that all revolutions fail in the end. Orwell could have written a long essay expressing such ideas but it is doubtful that many people would now be reading it. The success of Animal Farm is that it tells the sad tale of a group of creatures we care about, and how their hopes and dreams were dashed. Beyond the surface story, however, is the message that for ordinary people revolutions simply change one set of rulers for another. It is a depressing message but people are prepared to listen to it because it is told in a simple and entertaining way like all the best fables.

Taking The Castle of Otranto as your example, outline the main conventi

Taking The Castle of Otranto as your example, outline the main conventions of the knightly novel, and show how your knowledge ofTaking The Castle of Otranto as your example, outline the mainconventions of the black letter novel, and show how your knowledge of theseconventions affects your reading of Northanger Abbey. Is NorthangerAbbey most accurately described as parody of the Gothic genre, or isthere a more complicated race going on?Gothic novels purport to revive old stories and beliefs, exploringpersonal, psychical encounters with the taboo (Williams, 2000). Thegenre, as typified by The Castle of Otranto by Horace Walpole,involves a beautiful simple young woman who is held captive by anolder, powerful, evil man in his large, ancient and gloomy residencefor his own lustful purposes and who escapes, with the aid ofsupernatural manifestations, errors caused by false surmises andconjectures based on partial narratives (Hoeveler, 1995, p127) and ahandsome young hero. Walpoles novel centers around the tyrant wherethe female writers in the genre, for example, Ann Radcliffe, focusmore on the female victim and what she is thinking and feeling,exploring womens anxieties about their lack of control of theirfeelings, their bodies, and their property, and their desire forsomething far more extraordinary and exciting than simply to be adomestic woman. The use of the supernatural by Walpole is so frequentand monstrous as to excite laughter rather than terror but forRadcliffe and Austen the supernatural is not visible but is aninvisible hand that makes sure that good always triumphs and evil isalways punished (Andriopoulos, 1999) .It is necessary to be aware of these Gothic conve... ...omy and the Gothic Novel. ELH 66.3 (1999) 739-59.Austen, Jane. The Novels of Jane Austen. Ed. R.W. Chapman. 3rdedition.OxfordOUP, 1933-69Cudden, J.A. Dictionary of Literary Terms & Literary Theory. PenguinLondon, 1999.Hoeveler, Diane. Vindicating Northanger Abbey Mary Wollstonecraft,Jane Austen, and Gothic Feminism. Jane Austen and Discourses ofFeminism. Ed. Devony Looser. Houndsmills, Basingstoke, HampshireMacmillan, 1995. 117-35Jerinic, Maria. In Defense of the Gothic Rereading NorthangerAbbey. Jane Austen and Discourses of Feminism. Ed. Devoney Looser.Houndsmills, Basingstoke, Hampshire Macmillian, 1995. 137-49Neill, Edward. The Secret of Northanger Abbey. Essays in Criticism47 (1997) 13-32Williams, Anne. The standoff, the Horror Recent Studies in GothicFiction. Modern Fiction Studies 46.3 (2000) 789-99