Saturday, May 23, 2020

A Critical Analysis Of The Theory Of Endosymbiosis And It...

A critical analysis of the Theory of Endosymbiosis and it’s supporting evidence Abstract Introduction The endosymbiotic theory is an evolutionary theory explaining the origin of Eukaryotic cells from Prokaryotic, and is at present; the most widely accepted evolutionary theory of the Eukaryotic cell. The theory explains the origins of mitochondria and chloroplasts and their double membranes, suggesting that chloroplasts and mitochondria represent formerly free-living bacteria that were taken into a cell as an endosymbiont. Molecular evidence suggests that mitochondria developed from proteobacteria and chloroplasts from cyanobacteria. It is thought that the Prokaryotes may have entered the host cell as a parasite or source of nutrient for the host, however avoided digestion. The primitive chloroplast may have provided the host cell with crucial nutrients, and the primitive mitochondrion may have aided the exploitation of oxygen for the extraction of energy. In return the host cell offered a protected environment for the Prokaryotes to live in. This was the beginning of a symbiotic rela tionship between the primitive chloroplast and mitochondria, and the Eukaryotic cell. The theory was ridiculed for years due its controversial nature, however in 1967 Lynn Margulis, a biologist from Boston University, developed the modern Serial Endosymbiosis Theory. Primary Endosymbiosis vs. Secondary Endosymbiosis Primary endosymbiosis involves the engulfment of a bacterium by another

Monday, May 18, 2020

Essay about The Washington Monument - 4283 Words

The Washington Monument The Washington Monument, a memorial structure designed and constructed in the nineteenth century, signifies an important tribute to the prestigious role and achievements of our nation’s founding father. Ideas for such a monument first arose in 1783, by which time â€Å"the fame George Washington, Commanding General and first President of the United States, was assured in the pantheon of statesmen of the world† (1). It was during this year that the Continental Congress proposed an â€Å"equestrian statue† in honor of â€Å"Washington’s services and his unique role in the founding of the new Republic† (1). Despite the project’s popularity with the public, however, little action was taken following†¦show more content†¦Despite the difficulties that were faced during both the planning and construction of the Washington Monument, the impressive tributary obelisk still stands today as one of the nation’s â€Å"noblest architectural structures† (1). Prior to beginning construction in 1848, the government spent nearly seventy years in legislation. Shortly after it was decided in 1783 that an â€Å"equestrian statue† should be erected in honor of George Washington, a French landscape engineer by the name of Major Charles Pierre L’Enfant drew up the first plan for Washington’s future capital, including the statue as â€Å"one of the principal features of the Federal District† (1). The idea resurfaced after the death of George Washington in December of 1799, when a proposal made by U.S. Representative John Marshall suggested the erection of a marble monument under which the founder’s body would be deposited. But Congress could take no immediate action due to conflicting opinions in both the House and Senate and with Washington’s family members: when the House â€Å"appropriated $200, 000 for the construction of †¦ [a] ‘mausoleum of American granite and marble, in pyra midal form 100 feet square at the base and of proportionate height’† (1), the grant was opposed by the Senate and family members (who did not want to move the remains from the site where Washington had specifically asked they be placed). â€Å"Throughout the Nation there was a deep sense of disappointment over theShow MoreRelatedEssay on The Washington Monument991 Words   |  4 PagesThe Washington Monument The most stunning monument in our capital is the Washington Monument. At 555 feet high, it is the tallest such monument in the world. It is an obelisk by shape, yet not a true obelisk because it is not carved out of a single stone. The monument was built at intervals between 1848 and 1885. It memorializes George Washingtons achievements and his devotion to principles and to his country. The Washington Monument has an interesting history. The idea of a monument celebratingRead MoreThe Statue Of Liberty, The Washington Monument901 Words   |  4 Pages Monuments preserve a memory that serves as a reminder of a significant event or person. The Statue of Liberty, the Washington Monument, Bunker Hill Monument— these structures honor and immortalize remarkable occurrences in history, people, or concepts; and when it is time to construct a monument, many aspects of the established memorial need to be planned. Factors a group or agency should consider when memorializing an event or person and in creating a monument is the location, which should be inRead MoreDescriptive Essay On Lost And Found986 Words   |  4 Pagesexperienced once before. One of the most stressful times I have ever been a part of is when I lost my wallet in Washington D.C. It was this event that taught me a lesson about being responsible. As we arrived at the station, my family and I exited the train and headed to ground level. From there we proposed a plan. Our plan for the day was to visit the Lincoln Memorial, Washington Monument, the Capitol Building, and the White House. After my family and I devised our plan, we sought out the LincolnRead MoreThe Story Of My Life924 Words   |  4 PagesThe sun shone high, a little too high. Walking down the path of the Washington Monument in, quite obviously, Washington D.C., the Lincoln memorial looked bigger of an obstacle than my friends and I had thought itd be. I made a grand mistake of wearing a heavy shirt; sweat was dripping in torrents down my neck. Elli and Kennedie, my greatest friends who always remained faithful, were walking somewhat a few paces in front of me. The heat was very unbearable, but Ellis mom, who lagged behind me moreRead MoreShort Story : The Story Of The World 3079 Words   |  13 PagesOkay, so because Dak has the power to transform shapes of thi ngs and people, he has made each of us a tent in a part of Washington only we know about. Were going to have to stay here and plan until we stop Cassius because this is the most vulnerable part of the nation: the countrys capital, Violet explained as she lead me to my tent. I noticed once we got past the trees and rocks and into the hiding place that the tents were divided by color. The five on the left were green, the five on theRead MoreThe Liberty Bell, Washington Monument, The Bald Eagle918 Words   |  4 PagesThe symbols of this great nation are many. The Liberty Bell, Washington Monument, the Bald Eagle, the White House, and the document that is the foundation on which this country is built, the Constitution of the United States. These symbols are immediately recognized by the citizens of the United States and some internationally, however the one symbol that is universally recognized is the Stars and Stripes. It is the symbol of a free nation whose citizens are allowed to strive for the AmericanRead MoreGrand Canyon National Park, New York City, and the Washington Monunent Short Report1299 Words   |  6 Pageslandmarks that is visible from space (NATURE, CULTURE, AND HISTORY). Although the canyon is now a national park, it hasn’t al ways been one. Its first designation was as a Forest Reserve in 1893. It was not until much later that it became a National Monument. However, it still had not yet achieved the status of National Park. That status was official achieved in 1919 (History Culture). Although it was a National Park it was still not frequently visited, and only had, approximately, 44,173 visitorsRead MoreThe Statue Of Liberty936 Words   |  4 PagesThroughout centuries, architecture and monuments have given America the name it has today. Some of the oldest forms of art made on American soil hundreds of years ago are what is cherished dearly today. There are over a hundred different statues alone in the US that near and dear to us all but thousands forms of art that makes Americans proud to be called American. United States is a place that underwent plenty of struggles and monumental milestones to make it the powerful land it has become todayRead MoreHonoring The Veterans Essays1403 Words   |  6 Pag esHonoring the Veterans What is Honor Flight? It is an amazing organization that honors World War II and Korean veterans. The veterans go to Washington D.C. to see their monuments for an entire day and some even go for multiple days. The veterans finally get to see the monuments that were built for them. The Korean War memorial, the World War II memorial, and the beginning of Honor Flight all have a great story. Honor Flight is one the widest known organization that is dedicated to veterans. HonorRead MoreMaya Lin Vietnam Veterans Memorial Analysis1276 Words   |  6 Pagesand angered many people. Since them, works and designs she has created for competitions have been mainly memorials and remembrances based on historical events. Her works are intended to use the natural texture and geology of the space around the monument to its advantage in its creation. 2. The Vietnam Veterans Memorial Fund, a non-profit organization, began collecting private funds and donations to create a memorial. Over 8 million dollars were raised. A site was picked near the Lincoln Memorial

Tuesday, May 12, 2020

Outline Of The Oklahoma City Bombing - 1665 Words

Muskan Hossain American Terror: The Oklahoma City Bombing cements terrorism into the minds of citizens Thesis: Due to the Oklahoma City Bombing, U.S. citizens are corrected of their stereotypical thoughts towards terrorism; Terrorists aren’t commonly Muslims or foreign enemies. I. Overview II. The significance of the Oklahoma City Bombing A. Controversies that arose B. Questions thought and asked by the citizens C. Impact towards the Federal Government D. How it shook the illusion held by many Americans of a nation safe from the political unrest and terrorism outside its borders (an illusion that would be shattered for good on 9/11). III. Addressing an argument from the opposing viewpoint (Not all Muslims were†¦show more content†¦because U.S. citizens were not questioned of their motives until the first American terrorist bombing. Before then Muslims were doubted, questioned, and hated for all motives whether good or not., Due Muskan Hossain to the typical thought of Muslims being the ones to bomb buildings in the U.S. many people showed hatred to all Muslims until an American terrorist, Timothy, had bombed the Federal Building in Oklahoma City., and Timothy McVeigh and John J. McNamara were both American Terrorist Bombers that were involved in major city building bombings. . Thesis Statement Model #4: Thesis with Concession and Reasons This model both makes a concession to opposing viewpoint and states the reasons/arguments for the writer s main idea. While Not all Muslims were punished by the U.S., Due to the Oklahoma City Bombing, U.S. citizens are corrected of their stereotypical thoughts towards terrorismÍ ¾ Terrorists are commonly NOT Muslims or foreign enemies. because U.S. citizens were not questioned of their motives until the first American terrorist bombing. Before then Muslims were doubted, questioned, and hated for all motives whether good or not., Due to the typical thought of Muslims being the ones to bomb buildings in the U.S. many people showed hatred to all Muslims until an American terrorist, Timothy, had bombed the Federal Building in Oklahoma City., and Timothy McVeigh and John J. McNamara were both American Terrorist Bombers that were involvedShow MoreRelatedAnnotated Bibliography On Terrorism And Terrorism945 Words   |  4 Pages Formal Outline Topic: Terrorism General Purpose: To Persuade Specific Purpose: To Persuade the reader that terrorism exists and that is important for the U.S to increase their security in order to decrease the terrorism in the country. Thesis: Although terrorism has caused most of the world to increase their security, it still seems to not be enough to make the world safe, Therefore the U.S. should increase their securityRead MoreNational Response Framework for Terrorist Attacks559 Words   |  2 Pagesanticipated and prepared for properly (Pilat, 2005). While shortly after the Oklahoma City bombing and foreign nuclear scares of the Clinton administration, the emphasis of WMD attacks rested on nuclear weapons, it became readily apparent that biological weapons were equally if not more dangerous to the public (Chittaranjan, 1998). Along this line of thought, the federal government enacted the CONPLAN, a plan that outlines the status and treatment of certain terrorist attacks and how these attacksRead MoreA Strategic Plan For The Fbi1244 Words   |  5 PagesIn order to outline the beginnings of a strategic plan for the FBI, the planner must begin with the identification of mission scope. The FBI utilizes a St rategy Management System to â€Å"improve intelligence capabilities, critical incident response effectiveness, talent and technology readiness, and other performance objectives† (FBI, 2010, para. 1). In the case of the Bureau, there are multiple mission scopes: Protect the United States from terrorist attack and foreign intelligence activity. CombatRead MoreEssay about Violence in America2573 Words   |  11 Pagesbetween came the incidents at Ruby Ridge, Idaho, and Waco, Texas, involving dubious law enforcement assaults on separatists, which led to the terrorist bombing at Oklahoma City — the single worst terrorist act in American history. Since then, law enforcement agencies have thwarted twenty-four major domestic terrorist attacks.   Shootings and bombings at abortion clinics, the slaying of abortion providers by right-wing fanatics and racial disturbances, some of which involved flagrant police brutalityRead MoreEssay on Women in Afghanistan1708 Words   |  7 PagesWomen in Afghanistan Brief Outline of Afghanistan History: 1910’s-1920’s : Reform movements in Afghanistan 1933-1973 : Some reform, country remains fairly static 1978-1992 : Democratic Republic of Afghanistan 1979-1989 : Soviet Intervention 1992-1996: Islamist Mujanidin 1996-2001 : Taliban 2001-Present : U.S. Occupation, new government The reason I chose to study Islamic Feminism and Afghanistan, is that for many people, these words do not belong in the same sentence. AfghanistanRead MoreThe Principal Agent System1623 Words   |  7 PagesRefugee Act of 1980. This act created the Federal Refugee Resettlement Program, was reauthorized in 2002, and was intended to assist refugees in achieving self-sufficiency and economic stability upon their resettlement in the United States. This law outlines the government’s responsibility to provide refugees with cash assistance, employment training and placement, the opportunity to acquire sufficient English skills, and also specifies that all women are to be provided with all the same opportunitiesRead MoreThe Rise of Domestic Terrorism in the United States2030 Words   |  8 Pageshighway for trash cleanup, with mixed success. The political turmoil of the 1960s and 70s saw the emergence of a number of leftist terrorist groups, perhaps the most notable of which was the Weather Underground, which was responsible for a number of bombings in opposition to American foreign and domestic policy. The examples of the Klu Klux Klan and the Weather Underground reveal an essential fact about domestic terror in the United States; namely, that groups organize for a variety of reasons andRead MorePre-Columbian Period9302 Words   |  38 Pagesoperation of the new government and efforts soon began to improve upon it.[28] The territory of the newly formed USA was much smaller than it is today. A French map showing Les Etats Unis in 1790A series of attempts to organize a movement to outline and press reforms culminated in the Congress calling the Philadelphia Convention in 1787. The structure of the national government was profoundly changed on March 4, 1789, when the American people replaced the confederation type government of theRead MoreThe Right to Bear Arms in the United States2637 Words   |  10 PagesNichols). This man is pro-gun; he believes that in most cases talking and words can solve almost any situation. Although far too often the need for the sword (gun) is forgotten. James Nichols is the brother of the man who helped carry out the Oklahoma City bombings; his insight helps paint the picture of why Americans need guns. Many different events have impacted the institution of gun laws, although none may have been influential as Columbine. It seems that school shootings are usually the driv ingRead MoreModern History.Hsc.2012 Essay25799 Words   |  104 Pages1920s, the initial blow of the Depression was crushing†. (McIlvaine) Unemployment rates amongst workers skyrocketed as big business was forced to ‘let them go’. 100,000 people fired every week 1930-1933 (Leuchtenburg) 1 million unemployed in NY city alone. Cleveland had an unemployment rate of 50% in 1932. Akron 60%. Toledo 80%. The collapse of agriculture (especially cotton) in the south left many black americans without income. By 1932 over 50% of the Blacks in the South were unemployed.

Wednesday, May 6, 2020

Essay about Caged Bird - 650 Words

I Know Why the Caged Bird Sings Maya Angelou, in I Know Why the Caged Bird Sings, tells her story of how and when she grew up. In Arkansas at the time of Maya Angelous childhood, many things were looked upon as bad or unfavored. Mayas problem was that she was black and a woman. Her novel depicts her life in rural Stamps, Arkansas with her grandmother and in St. Louis, Missouri, where her mother resided. At the age of three Maya and her four-year old brother, Bailey, were turned over to the care of their paternal grandmother in Stamps. Southern life was filled with humiliation, violation, and displacement. These actions were exemplified for blacks by the fear of the Ku Klux Klan, racial separation of the town, and the many†¦show more content†¦She thinks she cannot be heroic like all the boys she read about in her comics, for the fact of being a girl. Being female was just as limiting for Maya as being black, and seemed to be something to struggle against rather than embrace. Maya knew that to be blac k and female is to be faced with violence and violation. In her society, blacks were no good and women were only useful for sex. Maya struggled throughout her childhood to accept her race and gender. This is brought into focus when she went to live with her mother and is raped by her mothers boyfriend. After Maya eventually reveals who did this to her, the man is killed. She believed that her own voice killed him. This childhood rape reveals the pain that African American women suffered as victims not only of racism but also sexism. She withdrew herself and vows never to speak again. Her mother feels that she has done everything in her power to make Maya talk, but she cannot reach her. She sends Maya and her brother back to Stamps. After Maya returned to Stamps, and with the help of her Teacher Ms. Flowers, she began to speak again. For the most part, though as a struggle, Mayas experiences have made her a much stronger person. African-American women, during Mayas time, faced great er troubles than a colored male would have. The society was racist and sexist as well. Maya saw this as a challenge and rose through everything, eventually becoming a successfulShow MoreRelated Maya Angelou as a Caged Bird Essay1153 Words   |  5 PagesMaya Angelou as a Caged Bird    The graduation scene from I Know Why The Caged Bird Sings illustrates how, living in the midst of racism and unequal access to opportunity, Maya Angelou was able to surmount the obstacles that stood in her way of intellectual develop and find higher ground.   One of the largest factors responsible for Angelous academic success was her dedication to and capacity for hard work, My work alone has awarded me a top place...No absences, no tardinesses, and my academicRead MoreI Know Why The Caged Bird Sings1482 Words   |  6 Pages Maya Angelou tells of her life experiences and struggles in her book â€Å"I Know Why the Caged Bird Sings† that gives us insight about Maya’s life as a young black girl growing up in a time of racism. The novel discusses various forms of oppression that she had to face as well cope with them. Robert A. Gross wrote an analysis for Newsweek about the book and claimed that Angelou’s book is not only an interesting story of her ow n experience, but also a portrayal of a Southern black communityRead MoreI Know Why The Caged Bird Sings1555 Words   |  7 Pages28th of May 2014, she was an Activist, acclaimed American poet, storyteller and autobiographer. However, all her accomplishments were born out of abuse, violence, neglect and pain, that she wrote about in her autobiographical novel, I know why the caged bird sings which was published in 1969. In the book, she wrote not only about the conflicts that plagued her for much of her life but also how the role they played in her life. Particular problem areas discussed include, the difficulties she experiencedRead MoreI Know Why The Caged Bird Sings948 Words   |  4 Pagesis a poet and award-winning author known for her acclaimed memoir I Know Why the Caged Bird Sings and her many poetry and essay collections. So many things happen to Maya Angelou but she was amazing and a brave woman too not everyone would be same after what happen to her. Maya Angelou has be come the most amazing singer, dancer, actress, poet and writer she is even an author of autobiography â€Å"I Know Why the Caged Bird Sings† a book that tells the things that setback and helped Maya to be who she isRead MoreI Know Why The Caged Bird Sings1445 Words   |  6 PagesPresentation I Know Why the Caged Bird Sings is a self-portraying record of Maya Angelou that shows how cherish for writing and having a solid character can assume a huge part in conquering bigotry and misery. Throughout the story, it is clear that Maya changes from being a setback of bigotry to end up distinctly a young lady with self-nobility and character that helps her to conquer partiality. The setting of I Know Why the Caged Bird Sings concentrates on the issues connected with bigotry thatRead MoreI Know Why The Caged Bird Sings1126 Words   |  5 PagesMaya Angelou was a gifted woman with one of the greatest voices of African American literature. Previously known as Marguerite Johnson, she was one of the most important women of our time. She was best known for her autobiography I Know Why the Caged Bird Sings. Not only was Maya Angelou able to overcome all the racial discriminations and interferences that she endured growing up, she was also able to prove to many people what a successful African American author and activist she was. She was a womanRead MoreI Know Why The Caged Bird Sings2695 Words   |  11 Pages I Know Why the Caged Bird Sings According to Willard Scott, â€Å"Positive Feelings come from being honest about yourself and accepting your personality, and physical characteristics, warts and all; and, from belonging to a family that accepts you without question.† Maya Angelou illustrates this in I Know Why the Caged Bird Sings, an autobiography on herself. It illustrates Maya Angelou’s struggles of accepting herself because of some cruel experiences in her life. Maya was an African American girlRead MoreEssay on I Know Why The Caged Bird Sings1319 Words   |  6 Pagesseems to care much more about her than her father did. Thesis Statement: Maya Angelou faces many hardships, yet manages to overcome them all, in her autobiography, â€Å"I Know Why the Caged Bird Sings.† Maya Angelou faces many hardships, yet manages to overcome them all, in her autobiography, â€Å"I Know Why the Caged Bird Sings.† Maya is a strong willed, often stubborn, outgoing, somewhat outspoken, and rather intelligent girl. She becomes very tolerant due to some of her experiences. She also maturesRead MoreI Know Why The Caged Bird Sings Essay1097 Words   |  5 Pagesviews. She is one of the few recognisable civil rights activist working right beside Martin Luther Jr and many other leaders including presidents. Working in the Reagan and Bush ad ministry. She wrought a best-selling auto biography â€Å"I know why the caged bird sings†. Trough-out her legacy she continuously created poems promoting civil rights from her personal and social views. â€Å"still I rise â€Å"is one of her earlier working but is still consider one of the greatest poems on discussing the social views atRead MoreI Know Why The Caged Bird Sings2495 Words   |  10 PagesIn the memoir, I Know Why the Caged Bird Sings, Maya Angelou presents the theme: coming of age. This theme is shown throughout the book many times, espec ially when something big happens to her, changing the way that she reacts to things and the way that she sees things. Another way that this theme is shown throughout the book is the way that she words things in the beginning, vs the way that she words things in the end. The change in her writing style and her language shows this. Not only was she

Mexico the Yucatan Peninsula Free Essays

Mexico: The Yucatan Peninsula The Yucatan Peninsula is located in southeastern Mexico, which separates the Caribbean Sea from the Gulf of Mexico, on the northern coastline on the Yucatan Channel. The Yucatan Peninsula lies east of the Isthmus of Tehuantepec, a northwestern geographic divider separating the region of Central America from the rest of North America. The Yucatan Peninsula comprises of the Mexican states of Yucatan, Campeche, and Quintana Roo; the northern part Belize; and Guatemala’s northern subdivision of El Peten. We will write a custom essay sample on Mexico: the Yucatan Peninsula or any similar topic only for you Order Now Geology The peninsula is the exposed part of the large Yucatan Platform. The Yucatan Peninsula is an unconfined flat lying erosion landscape. Sinkholes, locally called cenotes are widespread in the northern lowlands. According to the Alvarez hypothesis, the mass extinction of the dinosaurs at the transition from the Cretaceous (K) to the Tertiary (T) Periods (the K-T Boundary) 65 million years ago was caused by an asteroid impact somewhere in the Caribbean Basin. The deeply buried Chicxulub Crater is centered off the north coast of the peninsula near the town of Chicxulub. The now-famous â€Å"Ring of Cenotes† outlines one of the shock-waves from this impact event in the rock of ~65 millions years of age, The presence of the crater has been determined first on the surface from the Ring of Cenotes, but also by geophysical methods, and direct drilling with recovery of the drill cores. Water resources Due to the extreme erosion nature of the whole peninsula, the northern half barely consists of any rivers. Where lakes and swamps are present, the water is marshy and is not suitable for drinking water. The thousands of sinkholes, locally called Cenotes throughout the region provide access to the groundwater system, and the cenotes have long been relied on by ancient and contemporary Mayan people. Vegetation The short and tall tropical jungles are the predominant natural vegetation types of the Yucatan Peninsula. The boundaries between northern Guatemala (El Peten), Mexico (Campeche and Quintana Roo), and western Belize are still occupied by the largest continuous tracts of tropical rainforest in Central America. However, these forests are suffering extensive deforestation. Etymology There is a popular myth that the name Yucatan comes from the Yucatec Maya phrase for â€Å"listen how they speak,† or â€Å"I don’t understand your words† — supposedly said by contact period Maya, when the first Spanish explorers asked, what the area was called. The proper derivation of the word Yucatan is widely debated. However, it is also claimed that the actual source of the name â€Å"Yucatan† is the Nahuatl (Aztec) word Yokatlan, â€Å"place of richness. † People The Yucatan Peninsula comprises a significant proportion of the ancient Maya Lowlands. There are many Mayan archaeological sites throughout the peninsula; some of the better-known sites are in Chichen Itza, Tulum and Uxmal. Indigenous Mayans and Mestizos of partial Mayan descent still make up a sizable portion of the region’s population, and Mayan languages are still widely spoken there. Economy In the late historic and early modern eras, the Yucatan Peninsula was largely a cattle ranching, logging, chicle and henequen production area. Since the 1970’s, the Yucatan Peninsula has fixed its economy towards tourism, especially in the Mexican state of Quintana Roo. Once a small fishing village, Cancun in the northeast of the peninsula has grown into a thriving city. The Riviera Maya, which stretches along the east coast of the peninsula between Cancun and Tulum, houses over 50,000 beds and is visited by millions of tourists every year. The best-known locations are the former fishing town of Playa del Carmen, the ecological parks Xcaret and Xel-Ha and the Mayan ruins of Tulum and Coba. Climate Like much of the Caribbean, the Yucatan Peninsula lies within the Atlantic Hurricane Belt, and with its almost uniformly flat terrain, it is vulnerable to these large storms coming from the east. The 2005 Atlantic Hurricane Season was a particularly bad season for Mexico’s tourism industry, with two forceful category 5 storms hitting, Hurricane Emily and Hurricane Wilma. The 2006 Atlantic Hurricane Season was a typical year which left the Yucatan untouched, but in the 2007 Atlantic Hurricane Season Yucatan was hit by the Hurricane Dean (which is also a category 5 storm); nevertheless Hurricane Dean left little damage on the peninsula despite heavy localized flooding. Strong storms called nortes can quickly descend on the Yucatan Peninsula any time of year. Although these storms pummel the area with heavy rains and high winds, they tend to be short-lived, clearing after about an hour. The average percentage of days with rain per month ranges from a monthly low of 7% in April to a high of 25% in October. Breezes can have a cooling effect; humidity is generally high, particularly in the remaining rainforest areas. Bibliography â€Å"Beautiful Underground Lakes Rivers. † Wonderfulinfo. com. 5 January 2010. http://www. wonderfulinfo. com/photos/underground/ â€Å"Climate and Weather of Mexico. † yahoo. answers. com. 26 Sept 2009. http://answers. yahoo. com/question/index? qid=20090419162859AAZ2D7m. crumb=eYF8u9vJN5s â€Å"Mapas de Mexico. † Mexicoadventourist. com. 5 January 2010. http://www. mexicoadventourist. com/Mapas/YucatanMap. jpg â€Å"Mexico’s Government. † Viva Mexico. 2 October 2009. http://staff. esuhsd. org/balochie/studentprojects/mexico/MexGovernment. html Parfit, Michael, â€Å"Yucatan Pe ninsula,† National Geographic. Aug 1996. 108-113. â€Å"Sunset over the Yucatan. † flickr. com/photos/afagen/. 5 January 2010. http://www. flickr. com/photos/afagen/2262221520/ The World And Its People. â€Å"Mexico – The Land Yucatan†. New York. Greystone Press. 1964. 34-35. â€Å"The World Factbook – Mexico. † CIA the World Factbook, 10 Sept 2009. ttp://www. cia. gov/library/publications/the-world-factbook/geos/countrytemplate_mx. html â€Å"Yucatani iguanaleso naplo. † atjeffs. blog. hu/2008. 5 January 2010. http://m. blog. hu/at/atjeffs/image/Yucatan_peninsula_250m. jpg â€Å"Yucatan Sunset. † flickr. com/photos/bjkresearch/. 5 January 2010. http://www. flickr. com/photos/bjkresearch/183792616/ â€Å"Yucatan Peninsula Sunset. † flickr. com/photos/kevmac66/. 5 January 2010. http://www. flickr. com/photos/kevmac66/3495944443/ â€Å"Yucatan Peninsula Resort. † Alwaysonvacation. com. 5 January 2010. http://www. alw aysonvacation. com/LSS/images/29225/YucatanPeninsula3BedroomsSle How to cite Mexico: the Yucatan Peninsula, Essay examples

Child Labor Laws in Nineteenth Century England free essay sample

This is a research paper based on Child Labor laws in 19th century England the working and living conditions of children then compared to now. This paper covers the evolution of child labor laws from 19th Century England through the present. The author discusses harsh working conditions endured and injuries suffered by children. Cited are specific pieces of legislation and non-profit campaigns aimed at stopping the phenomenon. Child labor in 19th century England was a shameful practice that many of us never look back on. The displaced working classes took it for granted that a family would not be able to support itself if the children were not employed. Therefore, children as young as five years old were working 12 hour shifts for less then 20 dollars a day. The conditions in which these children worked were below standards. It was a long and deadly fight to regulated child labor laws in England during the 19th century. We will write a custom essay sample on Child Labor Laws in Nineteenth Century England or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Today many of us take for granted the regulations on child labor; we act as if this is how it has been since the beginning. What we do not realize is how much child labor has progressed since the 19th century. Three hundred years may sound like a long time but when you consider how life was for a child then and compare it to a childs life today, I think youll begin to come to a better understanding of exactly what we have gone through to get where we are today.

Friday, May 1, 2020

Aluminum Alloy And Selective Laser Melting -Myassignmenthelp.Com

Question: Discuss About The Aluminum Alloy And Selective Laser Melting? Answer: Introduction Over the years previous, the 3d that is also known as the fabrication of the substance has led to the increase of the interest that will complicate it in the industry and the scholarly. more had been done on the AM innovation with the result distribution that includes the ISO and the ASTM guideline survey papers, books unique AM diaries and report guides.in contradiction to the normal assembling approaches, am gives the geometry without misuse of the materials and increasing the cost.in most metals, the system of the AM that is the specific laser liquefying has been the commonly used mostly and this can link to the general application ranges that is from 3D to mechanical design with the low volume me. in the selective laser melting a tiny portion of the metal powder is then dispersed at first, and the melting will be specifically done laser shaft within the environment. Similarly, in the examination of one layer, that stage has to be stopped by that one layer thickness and the powder is to be spread on the upper part of the metals(Gu, 2012). Literature review In most of the work had indicated that the aluminium alloy processing by the selective laser melting has been so cumbersome, by this the production of understandable components is done under high laser power of about 130w to 150w and with laser scanning speed that is slow. Most of the selective laser melting machine has higher power but that of the laser power is greater than it thus a significant factor.by combining the higher power and the reduction of the speed leads to melting thus forming a pool of the melted products that become very difficult to control. This will eventually lead to the balling of the melt and the power distribution system might be damaged. With the increase in power and reduction of the scanning speed, there will be the increase in the built time and cost of manufacturing(LEVY, 2009). Additive manufacturing This is a process by which the metal layers are joined together to form a CAD model through the building of objects, this done by combining several layers together. This process is also known as the standard tessellation language, where the shapes of the materials and the size of the components are defined. The data files are slice into the single layers by the software thus the additive manufacturing receives it as the instructions. The technology of the additive manufacturing uses the material in powder form. When the components have been manufactured, several activities have to take place e.g. it has to be polished, filled, cured, or painted with regards to the materials used(Kumar, 2006). Advantages of the additive manufacturing It is important as it uses small extraneous components to produce portions of the object thus an efficient process which reduces the waste during the manufacturing. By using less material during production this method reduces the steps of production thus reducing the amount of the energy consumed(Kumar, 2006). This method of production involves less waste thus the materials being used is not wasted during the manufacturing process thus an environmentally friendly process. This technique allows the producers to create a prototype. This will eventually save time, in times of production and development thus reducing the requirements during production leading to the use of few tools. With the reduction of the instructors, moulding and the required tools there will be the reduction in the cost of the manufacturing. The additive manufacturing technique allows for the innovation of the designs. The modifications of the design can be done anytime without extra cost. This technique can help in the reduction of the design complexity. The manufacturing using this traditional method can also be simply modified by this method(Murr, 2011). Application of the additive manufacturing The automotive industries require the development of new products. Since the development of the new products are very costly the industry has resorted to the use of the additive manufacturing technique in the designing and to develop automotive materials, the structure and the functioning parts of the components like the gearbox, drive shaft, drive shaft of the vehicle, and wheels(Kumar, 2006). Biomedical applications The additive manufacturing is a process that saves the life in the medical industry. The expansion of the applications of the additive manufacturing technology in the industry brought about by the development of the biologic science, biomaterials, and biomedicine has improved the use of this technology in the industry. The area of applications is, in the dental application, painted organs and in the bioprinting. Electronics industry Since the electronic products are reduced in terms of size and needs a high precision tool for the production, the industry uses this technology for the manufacturing of such products.it is also applied in the manufacturing of the embedded electronics, as it exists in the embedded frequency identification and object made of metals(Qian, 2015). Selective laser melting -materials, process parameters This is additive manufacturing new technology that comes up in the 1981 and has been consistently developed through different research.it began by 3D CAD file data being sliced into layers that lead to the formation of an image of layers of 2D in every layer. The files of the sliced data intern passed to the software package. The parameters, values and the report are then designed by the software. AM machine then is allowed to build the file in SLM. In the selective laser melting a tiny portion of the metal powder is then dispersed at first, and the melting will be specifically done laser shaft within the environment(Gu, 2012). Similarly, in the examination of one layer, that stage has to be stopped by that one layer thickness and the powder is to be spread on the upper part of the metals. The soft covering and the combination of the layers in the process are made together to form tough 3-D section. Process Parameters in SLM The parameter that influences the proper being of the selective laser melting is numerous.one can, therefore, understand this parameter by doing a correct analysis of these parameters, hence obtain the appropriate mechanisms in the designing process. The selective laser melting is required a larger number of parameter that affects the productivity of the last product. Some of the parameters the influences the process are, laser beam, the speed of scanning, the spacing of the hatch, properties of the powder, the thickness of the layer and chamber temperature. Scanning pattern: this is an important parameter to the process. This where the hatches are arranged in a proper way among the layers. The patterns can be moved in different ways depending the originality of the designer. The patterns are repeated in every layer regardless of the scanning. Laser power, scanning speed and density of the speed: the determination of other parameters of the process is based on the selection of the laser powder which is related to the size of the focus of the laser spot. The optimization of the energy density depends on the fine parameter turning, quality and the properties of the parameter that are involved in the process. The density of the energy is the ratio of the average energy applied to the volume of the material. This will eventually influence the last part of the process(Chen, 2011). Where P=Laser power (W), V=scan speed (mm/s). Size, the shape of the powder and distribution of particles: the distribution of the particles, shape and size of the powder plays an important part of the process. The distribution of the size particles refers to the amount of particle according to their ranges of the size. This is important as it gives the ratio of the bigger particles to that of the smaller particles, hence determines the rate of flow of the particles.in the selective laser technique, the layer thickness is to be smaller and the size of the grain should not be larger than the thickness of the layer. This can also influence the flow of the particle hence affect the SLM process. Temperature: in the building chamber, the temperature inside can consequently affect the process of selective laser melting. This must be accurately managed to obtain the desired outcome. The selection of this temperature will depend on the materials used in the processing. For the best outcome, the temperature should be high and distributed uniformly. Atmosphere: with the higher temperature and being of the oxygen in processing chamber may lead to oxidation.to correct this the environment should be protected to avoid decarburization hence reducing the toughness of the components. This will influence the mechanical property e.g. Ductility. With the presence of oxygen in the chamber, there will be the influence of the final product of the processing. But with the lowering of the temperature, there with be the rise in carbon ii oxide formation which is attached to the metals that are solidifying hence creating the bubbles of the gas. Some recommended gases can be used to limit the amount of oxygen gas in the chamber e.g. argon, helium and nitrogen(Murr, 2011). Porosity characterization This is one of the most important parameters that influence the reliability and the execution of the metals part during the processing. Several methods have been used to determine the measurement of the portion in terms of its volume and the dispersion of the porosity inside the fabricated substance ALSi10Mg.an example is water relocation technique, 2D SEM, and 3DXbeam microtomography. Results and discussion At high amplification, the accelerated inter metallic stages are on the are on the powder surface.in the examination of the EDS spot between the metals give a breakdown Mg mass to about 12% that remains close but somehow less than 16% of AL18Fe7Si10 phase. The reason for Mg focus that is lower in the small analysis is that the measurement of the metals compared with electron collaboration volume. The general building of the examination can be added due to the moderate decrease in the Mg focus. This will, in turn, reduce the focus to a particular degree. The powder particles comprise certain pores. With this, there can be an influence on the part of the final product. The spreading conduct of the powder can also be influenced by the satellites. The estimation of the molecules that were found divided by the dendrite arm from a normal pattern. The dendrite arm that is optional dividing changed from (0.4 to 4) for the measurements of the molecules was from (4 to 140). Conclusion: The dissolution of the size of the pool and the rate of the cooling can be effectively seen in the Rosenthal condition. The microstructure of the selective laser melting and the powder gas that is atomized used by the selective laser melting is in conjunction with the connection between the rate of cooling and the hardening size of the microstructure in light conventional aluminium silicon compounds. AL2O3 contains oxides that are staying separated imperfection in relation to the pores is built by the selective laser melting(Kumar, 2006). Even though some melt pool is not predictable we can simply conclude that the width of the melt pool, its depth and the height might increase with laser power, but with speed of the scanning it decreases and for the density of the energy it increases. The hardness of the component is seen as the result of the laser energy density. The surface roughness also has the significant role in the melt pool as uneven surface lead to the larger amount of the balling effects. Also, lower powder and a fast scan can also lead very low energy. A lot of Small individuals balls are formed at high energy as at this point long lifetime of the excessive pool with low velocity is seen. Due to the fluctuations in the speed of the scanning the melt pool of the powder case is bigger and rounded at the beginning and at the final stage while at the end there is no melt pool formation and the melt pool of no powder case is narrow and rounded at the start(LEVY, 2009). References. Dink, W., 2012. laser additive manufacturing of metallic components. WASHINGTON: internal material. Gibson, B., 2014. Additive Manufacturing. Brisbane: Springer. LEVY, K., 2003. effects of laser scan speed on porosity and dimensional change of the selective laser melting components. 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