Harriet Tubman Fight for Freedom free essay sample

A strong and powerful lady said these wise words: â€Å"There was one of two things I had a right to, liberty or death; if I could not have one, I would have the other; for no man should take me alive; I should fight for my liberty as long as my strength lasted, and when the time came for me to go, the Lord would let them take me†. The brave women who said these words were Harriet Tubman and she was one of the leaders of the Underground Railroad that helped slaves reach freedom. Although not an actual railroad of steel rails, locomotives and steam engines, the Underground Railroad was real nevertheless† (encyclopedia The Civil War and African Americans 329) The term â€Å"Underground Railroad† referred to the network of safe houses, transportation and the many very kind hearted people who risked their own lives to help the slaves escape from the Southern States to freedom. We will write a custom essay sample on Harriet Tubman Fight for Freedom or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Many different kinds of transportation were actually used. Sometimes the slaves would travel by foot or they could be hidden on boats, or hide in wagons or carts carrying vegetables or other goods The runaway slaves became known as â€Å"passengers†, and the route traveled was the â€Å"line† while people who helped out along the way were called the â€Å"agents†. Leaders like Harriet Tubman who would travel with the slaves that were escaping, were called â€Å"conductors†. Araminta Ross later known as Harriet Tubman was born a slave. Since her master needed money, he would rent her out to work for different masters doing housekeeping and childcare but Harriet was not good at this type of work and so she was often beaten and sent back to her original master. She eventually was made to work as a slave in the fields with her father. One day, while Harriet was working, a slave who was trying to escape ran past her. The slave’s master was running after him â€Å"Araminta (Harriet Tubman) was told to hold the slave that had tried to escape while the owner whipped him. She refused and tried to help the slave escape instead† (Journey to Freedom 13) She did this by getting in the way of the master who was running after the slave. This is how Harriet Tubman even as a child, helped a slave reach freedom and it was a big part of what inspired her to gain her own freedom and want to help other slaves escape. Even though Harriet Tubman was never taught to read or write she was very strong willed, religious and smart and she believed that people had the right to be free and did not think it was right to beat people just because they did not have white skin. Harriet was determined to be free and help others, â€Å"she would become a beacon of hope to other slaves, â€Å"Moses† helping to set her people free†. (Harriet Tubman Moses of the Underground Railroad 23) Araminta married a white man named Richard Tubman when she was in her twenties. She still worked as a slave for her master but at night she was allowed to stay with her husband. She tried to talk to her husband about escaping but he just got mad and said that he would turn her in, so without Harriet telling him, she and three of her brothers decided to escape. Her brothers became scared and turned back but Harriet made it to Philadelphia. When Harriet Tubman arrived in Philadelphia she later remembered feeling that â€Å"I had crossed the line of which I had so long been dreaming. I was free. She said she felt as if she were in heaven. † (Harriet Tubman Moses of the Underground Railroad 35) She got a job in Philadelphia and saved as much money as she could so that she could help other slaves to escape. Harriet Tubman became active with the â€Å"Philadelphia Vigilance Committee†. This was a group that provided one of the stations of the Underground Railroad that helped runaway slaves. She was very anxious to become involved. Her first trip to rescue slaves was a trip to bring her sister and family to freedom. Harriet was an excellent planner and thought out every detail. She arranged for her brother-in-law to pose as an agent for a master and pretend that his master wanted to see the slaves before purchasing. The plan worked and Harriett’s sister, husband and family were able to calmly walk away without anyone suspecting that they were going to escape. Harriet had many helpers or â€Å"agents† helping her. She used signals to let others know when it was safe to go from one place to another. Harriet’s sister and her family were able to crawl on a wagon that was carrying vegetables and make it all the way to Baltimore. Harriet met them in Baltimore and got them safely to Philadelphia by planning the entire route and hiring the necessary transportation and agents to help. Harriett Tubman was herself a fugitive and could have been caught anytime but he was brave and believed that she â€Å"heard the voice of god† and that He was telling her what to do to help the slaves escape. On another of her trips south to help free slaves, she sent a message to her husband asking him to join her in the North but she found out that he had married someone else. This made Harriett even more determined. She returned to the South nineteen times. The slaves would know who she was because of the song she would sing. â€Å"Dark and thorny is the pathway, Where the pilgrim makes his ways; But beyond this vale of sorrow, Lie the fields of endless days. (The Underground Railroad in American History 65) Each time she came back she would bring a group of 4 to 5 slaves with her. She was personally responsible for bringing over 70 slaves to freedom, and is given credit for helping many more. It was never an easy trip. Even though there were, at times, safe places to stay along the way, most of the journey was done by foot and at night. Sometimes when they were traveling at night it would be so dark that the only way they could tell which direction they were going was to try to feel the moss on the trees since the moss grew thicker on the North side. She would always leave on a Saturday night because on Sunday’s the slaves did not have to work and they would not be missed until Monday. Many times the slaves that came with her would become weak and scared and want to return, but she would not allow this because if one of them talked, then everyone who was set to help them now or in the future would be at risk. â€Å"The whole network of safe houses, agents and white and black allies who made the Railroad possible would be put in danger†. Harriet Tubman Moses of the Underground Railroad 59) At one point, one of the slaves traveling with her became scared, Harriet always traveled with a gun and she took out her gun and said â€Å"do you think I would let so many die just for one coward man? † Harriett Tubman Moses of the Underground Railroad 59) She became very well known and even had a reward of $40,000 for her capture. In 1850 it became even more dangerous for slaves escaping to the North because of the Compromise of 1850 â€Å"It required citizens to assist in the recovery of fugitive slaves†. There were posters that gave the names of slaves and stated â€Å"You’ve crossed the treacherous border states and, sor far, eluded slave catchers. But you can feel their breath, and as you cross into New England, you’ve heard tell of a law giving anyone with a badge not just the power but the obligation to arrest you. † (The Boston Globe, Sepember 26, 2010) Because of this, Canada was becoming the safest place for escaping slaves. Canada was governed by the British who had passed the â€Å"Abolition of Slavery Act† in 1834. In Canada â€Å"Emancipation was not only a word in the dictionary but an action to liberate one’s destiny. Harriet Tubman now helped slaves escape all the way to Canada because even slaves that had escaped to states in the North were not safe and could be sent back. During one of her journeys to Canada she was helping a group of slaves going from Philadelphia to Canada, the slaves were sure they were going to be caught and sent back but Harriett helped them take a train over a bridge that went to Canada and when they arrived in Canada â€Å"Tubman ran to one of the doubting slaves and said â€Å"You shook the lion’s paw, Joe. You’re free† Harriet not only had to overcome the slave states in the South, but the efforts of the Southern States to get their slaves back. The Dred Scott case before the Supreme Court in 1857 made her efforts to keep slaves free in the North more difficult. It ruled that Black’s had no rights and could be kept as slaves. â€Å"Abraham Lincoln opposed this decision and in his campaign speeches for the presidency he said the Supreme Court should not have denied equal rights to African Americans†. (Journey to Freedom 25) It was not until the end of the Civil war that the Blacks were freed. During the civil War Harriet aided the Union Army she helped set up field hospitals and formed a group of African American Scouts on a raid that freed 700 slaves. Using her skills from the Underground Railroad, she let them through the woods behind enemy lines (Journey to Freedom 26) after the war she continued helping the freed slaves to survive by buying food and get educated by fundraising for a school. Harriett Tubman truly was the â€Å"Moses† for her people helping lead them out of slavery. Harriett Tubman lived a long life dying in 1913 at the age of 93.

Edward sciccorhands review Essay Example

Edward sciccorhands review Essay Example Edward sciccorhands review Essay Edward sciccorhands review Essay Essay Topic: Batman Yet again Tim Burton has brought a masterpiece to our screens, this is indefinitely his best work following fankenwenie (1984), and batman (1989). Its the story of a shy lonely man (Johnny Depp) who finds friends, a lover, and then rejection in the heart of suburbia. Like the best fairytales, the story can be read many ways.  Scissorhands is arguably Burtons most personal film, a moving portrait of an imaginative outsider who cannot touch what he desires without harming or damaging it.  Tim has brought a great supply of cinematography once again, especially when he pans across the family and introduces them at the same time by doing this. While hearing slow and classical music to represent the difference in feeling from confused to happy and admiration. Burton mixes classic fairytale themes to create an original and touching character in Edward. Taken from his gothic castle to a colourful and romanticized suburban neighborhood he changes the lives of the towns people forever. The first half of the film is very funny, full of subtle physical comedy and gentle satire on suburban life. Edward brings his artistic skill to the town and the people almost ignore his creepy, weird and disturbed appearance. Then he begins a longing romance for Kim (Wynona Ryder), the girl he shares a house with but who seems to want nothing to do with him. He eventually wins her love, but is exploited by and then violently rejected by the towns people. The film is made with a skill far exceeding all of Burtons previous works of art. The unforgettable images make this a film to remember. Every performance is amazing. Johnny Depp brings a feeling of scared emotion to his almost silent character that lingers long in the memory. I almost forgot who was playing the part. Dianne Wiest and Alan Arkin are, respectively, touchingly real and hilariously blank as the parents who adopt him. Winona Ryder brings warmth and beauty to her supporting role as the object of Edwards affectations, who comes to love him for his artistic vision. Anthony Michael Hall is suitably menacing as the jealous jock that eventually gets his what he is deserved, and Kathy Baker funny as the sex-starved, Tom Jones-listening housewife. Finally, Vincent Price, in his last feature film role, brings extra resonance as Edwards inventor.  Some people criticize the plot holes such as where did he get the ice? They are missing the point, as this fairytale bears no relation to the real world, except in its themes. You have to suspend your disbelief. Edward is the most normal person in the movie and it is the twisted towns people who are the real monsters, resulting in his loss of innocence. Edward represents, among other things: a childlike imagination; the unconditional love of an animal; someone who longs for love and close affection. The famously beautiful scene where Edward makes an ice-sculpture as Kim dances in the snow is the ultimate representation of the artist communicating his feelings through his work. This film is almost perfect in its own way, even with the unfortunately sad ending.  To sum up, I believe Burton will never make anything near the depth and emotion of this amazing film again. Its funny, sad at times and visually striking. This was an outstanding movie in everyway.

Technological Advances In Video Games Research Paper

Technological Advances In Video Games - Research Paper Example 2000s – A virtual universe F. Future technological developments of the video game industry G. Conclusion Technological Advances in Video Games Through the Years The video game industry has evolved into what it is now through the advancement in technological developments. This essay aims to present the technological advances that the video game has undergone spanning more than 50 years of constant innovations. A. The early beginnings (1947 to 1960s) In January 1947, a patent was filed by Thomas T. Goldsmith Junior and Estle Ray Mann for the first electronic video game, the Cathode-Ray Tube Amusement Device, where the players hit targets printed on overlays through light beam missiles by just adjusting knobs (Polsson , par 1). Later in 1952, a tic-tac-toe game, Noughts and Crosses, became the first known computer game which was created by A. S. Douglas (KCTS Television 1). It ran on the Electronic Delay Storage Automatic Calculator (EDSAC), a big Cambridge University computer. T his game enabled a person to play tic-tac-toe against a computer player. Six years later, Tennis for Two, an interactive game which uses an analog computer and an oscilloscope as a screen was created by American physicist Willy Higinbotham to entertain visitors of the Brookhaven National Laboratory (KCTS Television 2). A milestone was achieved in 1962 when Steve Russell created the Spacewar! which ran on a PDP-1 computer and uses a vector-graphics screen. The game consists of two small flying spaceships which are controlled by two players with joysticks and buttons (Polsson , par 4). The â€Å"Brown Box†, the first console that works on a standard television was created by German-born television engineer, Ralph Baer in 1967. This marked the birth of the first television ping-pong video game system (Polsson , par 9). Baer later applied for a patent for his invention. B. 1970s – The video game empire is born a. Home game console The 1970s was the start of the video game empire. It was in the year 1971 when Nolan Bushnell created Computer Space, the first coin arcade-style game and first commercial video game (Polsson , par 19). This game did not gain much popularity though, as that of the Magnavox Odyssey, which was the first home game console which contains 12 different games, including Ping-Pong (KCTS Television 6). This console was also the first to use a light gun for target shooting. Cards are inserted to select the games. The Odyssey however only used â€Å"simple black and white graphics enhanced by plastic overlays for the television screen† (Miller , par 4). In 1975, Atari sold a home version of Pong whose â€Å"unique feature is the single chip that produces both an on-screen score and the sound the game makes when the paddle hits the ball† (Time Inc. 3). In August of 1976, Fairchild Camera and Instrument introduced the first programmable home video game system (Miller , par 11). Moreover, it boasted of 16-color graphics and a variety of games as programmed by removable ROM cartridges. A year after, Atari launched the Atari 2600 which is the first multi-game home console which had cartridges that store game information (KCTS Television 9). It included the famous games Space Invaders, Breakout, Missile Command and Combat. It was during this decade that home computers were released in North America such as the Apple II, the TRS-80 and the Commodore PET, along with the famous Atari 400/800. b. Arcades Aside from home computers, arcade games rose in popularity because consumers could just

Six Sigma Term Paper Example | Topics and Well Written Essays - 2500 words

Six Sigma - Term Paper Example In this respect, a manufacturer produces products that are of the same quality standards and which do not have defects that could lender them unusable and inefficient in performance of the intended services. Conclusively, Six Sigma enables manufacturers to produce products that are within a level of quality that is not extremely different from each other so long as they have a similar brand name. Introduction In the initial implementation of Six Sigma, the aspects that manufacturers considered were focused on the defects and products without defects. These manufacturers set some platform for measuring the standards according to outlined parameters. With Six Sigma, many manufacturers were able to establish parameters to moderate their production of commodities in the market so that the products were able to compare to the earlier produced having similar brand name. However, with time, some parameters that were related to time were developed to measure quality in the process of product ion so as to indicate the importance of efficiency. ... This means that efficiency in production is an aspect that is essential to measure the quality of production that could be experienced in any manufacturing company because it plays an essential role (Eckes, 2003, p53). Due to the numerous benefits associated with this management approach, its acceptance by various fields/organizations s been positive. This has been due to the fact that it effectively addressed problems experienced in the use of traditional management approaches. Other aspects of the Six Sigma included customer satisfaction, reduction in cost, increase in profit and reducing the pollution effects resulting from the use of a product. According to these values, people ensure that they improve the quality of production by ensuring that they are no issues/properties that cause defects while maintaining lowest levels of variability in manufacturing and business processes. This ensures that all people using the strategy are able to moderate the various things in the process of production so that they can ensure that they can sustain high quality or raise it, which would be beneficial to the company in terms of the sales level. The process uses some aspects of quality management to ensure that all the people are able to analyze the process of production so that it is acceptable in production. In this aspect, various things are put into consideration in the course of production to ensure that production has met some quality standards and are within some standards of production. On the other hand, according to the standards used in Six Sigma strategy, the producers are categorized in relation to their level of expertise on the production process (Schonberger, 2008, p.15). Aspects of Six Sigma In the

Information Technology-Use of Statistical Measures in Research Essay

Information Technology-Use of Statistical Measures in Research - Essay Example This paper studies the use of two of the most common statistical measures used in information technology research viz. measures of central tendencies and variability. Statistics enables the researcher in viewing the collected data in two ways. Descriptive statistics describes the shape of the data. Frequency and distribution are forms of descriptive statistics that help in this. Descriptive statistics uses measures such as mean, median, mode, correlation ,covariance etc.This data may be a sample or population data and we may have population mean compared to sample means etc. Inferential statistics attempts to fit a model to collected data and establishes causality .Inferential statistics also deals to develop predictive models which are based on causality analysis. In this paper mainly simple concepts of descriptive statistics are explored and inferential statistics is not touched upon. Statistical measures, not having real existence, simply support an argument or hypothesis and are just mental constructs. While statistics helps in summary organization of data, interpretation of the same, on its way to hypothesis, is the primary task of the resea rcher. Comparative cost of ownership analysis of Server Operating Systems was done with elaborate use of mean analysis and t test significance (Cahner, 1997). Mean and standard deviation model, multivariate model, Markov process model and time series model were used as part of statistical technique in developing Misuse Detection Systems (Christina, 1997).Statistical user profiles were used as part of multilayered security system (Steve, 1999).A combination of arithmetic mean, median and standard deviation gave sufficient support to help conclude on Survey results on Operating systems'(David, 1998). Discussion A basic primer of descriptive statistics is necessary not only for understanding such concepts but also for pointing to their specific use on research data. "The most frequently used average is the Mean, which is the balance point in a distribution. Its computation is simple - just add up the scores and divide by the number of scores.Formally mean is the value around which the deviations sum to zero.The formal definition also explains as to why informally one defines the mean as the balance point in a distribution. At mean value the positive and negative deviations balance each other out. A major drawback of the mean is that it moves in the direction of extreme scores. If in any two distributions most values are about same size however in one distribution one or two values are inordinately high then the mean of such a distribution would be pulled up greatly in comparison to the other distribution. This is a skewed distribution. For such skewed distributions, a different average, the Median, which is defined as the middle score is used. To get an approximate median, scores are put in order from low to high and count is made till middle score, which is set as median. The Mode is simply the score with highest frequency. The mode is sometimes used in informal

Summary and Analysis of the Compton Effect

Summary and Analysis of the Compton Effect En = nhf (1) where En is the energy, n is a non-negative integer, h is Plancks constant, and f is the frequency of the photon.2 In 1905, Albert Einstein extended Plancks inference to include not only black body radiation but all electromagnetic waves! Therefore, Einstein hypothesized that light is quantized with energy proportional to its frequency.3 The obvious principle to be deduced from these discoveries is that light possessed attributes of waves and particles! In 1922, Arthur Holly Compton solidified Plancks assumption and therefore firmly established a new era of physics. Compton theorized and then experimentally demonstrated that electromagnetic waves had the properties of particles. Classically, x-rays would shake the electrons of a target material at the same frequency of the x-ray. Hence, the wavelength of radiation from the oscillating electrons would be identical to the wavelength of the incoming xrays. 1 However, it was observed that x-rays were more easily absorbed by materials than waves of longer wavelength. In other words, the scattered  x-rays were of longer wavelength.4 This was contrary to the predictions of classical physics. Compton realized though, that if the interaction was modeled as a collision between two particles (electron and photon), the scattered x-rays would-be of longer wave length (compared to the incident-rays) because the recoiling electron would acquire some of the energy and momentum of the  incoming x-ray.4 Since wavelength is inversely proportional to frequency, the frequency of the scattered x-rays was less. From eq. (1), it is seen  that the energy would also be decreased. When Compton carried out this experiment in 1922 using molybdenum as his target, he verified his theory and provided even more evidence that light also possessed a mass less particle nature Detailed Description of Compton Effect   the elastic scattering of electromagnetic radiation by free electrons, accompanied by an increase in wavelength; it is observed during scattering of radiation of short wavelength-X rays and gamma rays. The corpuscular properties of radiation were fully revealed for the first time in the Compton Effect. The Compton effect was discovered in 1922 by the American physicist A. Compton, who observed that X rays scattered in paraffin have a longer wavelength than the incident rays. Such a shift in wavelength could not be explained by classical theory. In fact, according to classical electrodynamics, under the influence of the periodic electric field of an electromagnetic (light) wave, an electron should oscillate with a frequency equal to that of the wave and consequently should radiate secondary (scattered) waves of the same frequency. Thus, in classical scattering (the theory of which was provided by the British physicist J. J. Thomson and is therefore called Thomson scattering) the wavelength of the light does not change. An elementary theory of the Compton effect based on quantum concepts was given by Compton and independently by P. Debye. According to quantum theory a light wave is a stream of light quanta, or photons. Each photon has a definite energy Ø ¹ =hv=hc/ÃŽÂ »and a definite momentum pÃŽÂ ³= (h/ÃŽÂ »)n, where ÃŽÂ » is the wavelength of the incident light (vis its frequency),cis the speed of light,his Plancks constant, and n is the unit vector in the direction of propagation of the wave (the subscript ÃŽÂ ³ denotes a photon). In quantum theory the Compton Effect appears as an elastic collision between two particles, the incident photon and the stationary electron. In every such collision event the laws of conservation of energy and momentum are obeyed. A photon that has collided with an electron transfers part of its energy and momentum to the electron and changes its direction of motion (it is scattered); the decrease in the photons energy signifies an increase in the wav elength of the scattered light. The electron, which previously had been stationary, receives energy and momentum from the photon and is set in motion (it experiences recoil). The direction of motion of the particles after the collision, as well as their energy, is determined by the laws of conservation of energy and momentum (Figure 1). Elastic collision of a photon and an electron in the Compton effect. Before the collision the electron was stationary:pÃŽÂ ³and pÃŽÂ ³are the momentum of the incident and scattered photons, pe=mvis the momentum of the recoil electron (vis its velocity),(is the photons scattering angle, and à ¸ is the angle of escape of the recoil electron relative to the direction of the incident photon. Simultaneous solution of the equations expressing the equality of the summed energies and momentums of the particles before and after the collision (assuming that the electron is stationary before the collision) gives Comptons formula for the shift in the wavelength of the light: =ÃŽÂ » à ¢Ã‹â€ Ã¢â‚¬â„¢ÃƒÅ½Ã‚ »=ÃŽÂ »0(1 Ë- cos ÃŽÂ ¸) Here ÃŽÂ » is the wavelength of the scattered light, ÃŽÂ ¸ is the photons scattering angle, and ÃŽÂ »0=h/mc= 2.426 ÃÆ'- 10Ë-10cm = 0.024 angstrom (Ã…) is the Compton wavelength of the electron (mis the mass of the electron). It follows from Comptons formula that the shift in the wavelength does not depend on the wavelength ÃŽÂ » of the incident light itself. It is solely determined by the scattering angle ÃŽÂ ¸ of the photon and is maximal when ÃŽÂ ¸ = 180 °, that is, when scattering is straight back: max= 2ÃŽÂ »o. Expressions for the energy Ø ¹eof the recoil, or Compton, electron as a function of the angle à ¸ of its escape may be obtained from the same equations. The dependence of the energy Ø ¹ ÃŽÂ ³ of the scattered photon on the scattering angle ÃŽÂ ¸, as well as the dependence of Ø ¹eon à ¸, which is related to it, is shown in Figure 2. From the figure it is apparent that the recoil electrons always have a velocity component in the direction of motion of the incident photon (that is, à ¸ does not exceed 90 °). Experiment has confirmed all the above theoretical predictions. The correctness of the corpuscular concepts of the mechanism of the Compton effect-and thus the correctness of the basic assumptions of quantum theory-has been experimentally proved. In actual experiments on the scattering of photons by matter, the electrons are not free but are bound to atoms. If the energy of the photons is high in comparison with the binding energy of the electrons in the atom (X-ray and gamma-ray photons), then the electrons experience a recoil strong enough to expel them from the atom. In this case the photon scattering proceeds as if with free electrons. However, if the energy of the photon is not sufficient to tear the electron from the atom, then the photon exchanges energy and momentum with the entire atom. Since the mass of the atom is very great compared to the photons equivalent mass (which, according to the theory of relativity, equals  £y/c2), the recoil is virtually nonexistent; therefore, the photon Dependence of the energyØ ¹ÃƒÅ½Ã‚ »of the scattered photon on the scattering angleÃŽÂ ¸(for convenience, only the upper half of the symmetrical curve is depicted) and the dependence of the energy Ø ¹eof the recoil electron on the angle of escape 0 (lower half of the curve). Quantities related to the same collision event are labeled with identical numbers. The vectors drawn from point 0, at which the collision between the proton with energy Ø ¹ÃƒÅ½Ã‚ ³ and the stationary electron occurred, to corresponding points on the curves depict the state of the particle after scattering: the magnitudes of the vectors give the energy of the particles, and the angles formed by the vectors with the direction of the incident photon define the scattering angle à ¸ and the angle 0 of the recoil electrons path. (The graph was plotted for the case of scattering of hard X rays with wavelengthhc/Ø ¹ÃƒÅ½Ã‚ ³= ÃŽÂ ³o= 0.024 Ã….)  is scattered without a change in its energy (t hat is, without a change in its wavelength, or coherently). In heavy atoms only the peripheral electrons are weakly bound (in contrast to the electrons filling the inner shells of the atom), and therefore the spectrum of the scattered radiation has both a shifted (Compton) line, from scattering by the peripheral electrons, and an un-shifted (coherent) line, from scattering by the entire atom. With increasing atomic number (nuclear charge) the electron binding energy increases, the relative intensity of the Compton line decreases, and that of the coherent line increases. The motion of the electrons in atoms leads to a broadening of the Compton lines in the scattered radiation. This occurs because the wavelength of the incident light appears to be slightly changed for moving electrons; in addition, the amount of change depends on the magnitude and direction of the electrons velocity (the Doppler effect). Careful measurements of the intensity distribution in a Compton line, which reflects the velocity distribution of the electrons in the material, has confirmed the correctness of quantum theory, according to which electrons obey Fermi-Dirac statistics. The simplified theory of the Compton Effect examined here does not permit the calculation of all characteristics of Compton scattering, particularly the intensity of photon scattering at various angles. A complete theory of the Compton Effect is provided by quantum electrodynamics. The intensity of Compton scattering depends on both the scattering angle and the wavelength of the incident radiation. Asymmetry is observed in the angular distribution of the scattered photons: more photons are scattered forward, and the asymmetry increases with increasing energy of the incident photons. The total intensity of Compton scattering decreases with an increase in the energy of the primary photons (Figure 3); this indicates that the probability of the Compton scattering of a photon passing through matter diminishes with decreasing energy. Such a dependence of intensity on  £y determines the place of Compton scattering among the other effects of interaction between matter and radiation that ar e responsible for loss of energy by photons in their passage through matter. For example, in lead the Compton effect makes the main contribution to the energy loss of photons at energies of the order of 1-10 mega electron volts, or MeV (in a lighter element, aluminum, this range is 0.1-30.0 MeV); below this region it is surpassed by the photoelectric effect, and above it by pair production. Compton scattering is used extensively in studying the gamma radiation of nuclei; it is also the basis of the principle of operation of some gamma spectrometers. The Compton effect is possible not only for electrons but also for other charged particles, such as protons; however, because of the protons large mass its recoil is noticeable only during the scattering of photons with very high energy. The double Compton effect consists of the formation of two scattered photons in place of a single incident photon during scattering by a free electron. The existence of this process follows from quantum electrodynamics; it was first observed in 1952. Its probability is approximately a hundred times less than that of the ordinary Compton effect. Graph showing the dependence of the total Compton scattering intensity Inverse Compton effect. If the electrons on which electromagnetic radiation is scattered are relativistic (that is, if they are moving with speeds close to the speed of light), then in an elastic collision the wavelength of the radiation will decrease: the energy and momentum of the photons will increase at the expense of the energy and momentum of the electrons. This phenomenon is called the inverse Compton effect and is often used to explain the radiation mechanism of cosmic X-ray sources, the production of the X-ray component of the background galactic radiation, and the transformation of plasma waves into high-frequency electromagnetic waves. Description of the phenomenon By the early 20th century, research into the interaction ofX-rayswith matter was well underway. It was known that when a beam of X-rays is directed at an atom, an electron is ejected and is scattered through an angleÃŽÂ ¸.Classical electromagnetismpredicts that the wavelength of scattered rays should be equal to the initial wavelength;-9-2[3]however, multiple experiments found that the wavelength of the scattered rays was greater than the initial wavelength. In 1923, Compton published a paper in thePhysical Reviewexplaining the phenomenon. Using the notion ofquantized radiationand the dynamics ofspecial relativity, Compton derived the relationship between the shift in wavelength and the scattering angle: Where ÃŽÂ »is the initial wavelength, ÃŽÂ »Ãƒ ¢Ã¢â€š ¬Ã‚ ²is the wavelength after scattering, his thePlanck constant, meis the mass of the electron, cis thespeed of light, and ÃŽÂ ¸is the scattering angle. The quantityhà ¢Ã‚ Ã¢â‚¬Å¾mecis known as theCompton wavelengthof the electron; it is equal to2.43ÃÆ'-10à ¢Ã‹â€ Ã¢â‚¬â„¢12m. The wavelength shiftÃŽÂ »Ãƒ ¢Ã¢â€š ¬Ã‚ ²Ãƒ ¢Ã‹â€ Ã¢â‚¬â„¢ÃƒÅ½Ã‚ »is at least zero (forÃŽÂ ¸= 0 °) and at most twice the Compton wavelength of the electron (forÃŽÂ ¸= 180 °). Compton found that some X-rays experienced no wavelength shift despite being scattered through large angles; in each of these cases the photon failed to eject an electron.Thus the magnitude of the shift is related not to the Compton wavelength of the electron, but to the Compton wavelength of the entire atom, which can be upwards of 10à ¢Ã¢â€š ¬Ã¢â‚¬ °000 times smaller. Compton Scattering the scattering of3.html#c4x-raysfrom electrons in a carbon target and found scattered x-rays with a longer wavelength than those incident upon the target. The shift of the wavelength increased with scattering angle according to the Compton formula: Compton explained and modeled the data by assuming a particle (photon) nature for light and applying conservation of energy and conservation of momentum to the collision between the photon and the electron. The scattered photon has lower energy and therefore a longer wavelength according to the2.html#c3Planck relationship. At a time (early 1920s) when the particle (photon) nature of light suggested by the1.html#c2photoelectric effectwas still being debated, the Compton experiment gave clear and independent evidence of particle-like behavior. Compton was awarded the Nobel Prize in 1927 for the discovery of the effect named after him. Compton Scattering Data Comptons original experiment made use of molybdenum K-alpha x-rays, which have a wavelength of 0.0709 nm. These were scattered from a block of carbon and observed at different angles with a2Bragg spectrometer. The spectrometer consists of a rotating framework with a calcite crystal to diffract the x-rays and an ionization chamber for detection of the x-rays. Since the spacing of the crystal planes in calcite is known, the angle of diffraction gives an accurate measure of the wavelength. Examination of the Compton scattering formula shows that the scattered wavelength depends upon the angle of scattering and also the mass of the scattered. For scattering from stationary electrons, the formula gives a wavelength of 0.0733 nm for scattering at 90 degrees. That is consistent with the right-hand peak in the illustration above. The peak which is near the original x-ray wavelength is considered to be scattering off inner electrons in the carbon atoms which are more tightly bound to the carbon nucleus. This causes the entire atom to recoil from the x-ray photon, and the larger effective scattering mass proportionally reduces the wavelength shift of the scattered photons. Putting the entire carbon nuclear mass into the scattering equation yields a wavelength shift almost 22,000 times smaller than that for an unbound electron, so those scattered photons are not seen to be shifted. The scattering of photons from charged particles is called Compton scattering after Arthur Compton who was the first to measure photon-electron scattering in 1922. When the incoming photon gives part of its energy to the electron, then the scattered photon has lower energy and according to the2.html#c3Planck relationshiphas lower frequency and longer wavelength. The wavelength change in such scattering depends only upon the angle of scattering for a given target particle. The constant in the Compton formula above can be written and is called the Compton wavelength for the electron. The formula presumes that the scattering occurs in the rest frame of the electron Compton scattering occurs when the incident x-ray photon is deflected from its original path by an interaction with an electron. The electron is ejected from its orbital position and the x-ray photon loses energy because of the interaction but continues to travel through the material along an altered path. Energy and momentum are conserved in this process. The energy shift depends on the angle of scattering and not on the nature of the scattering medium. Since the scattered x-ray photon has less energy, it has a longer wavelength and less penetrating than the incident photon. Compton Effect was first observed by Arthur Compton in 1923 and this discovery led to his award of the 1927 Nobel Prize in Physics. The discovery is important because it demonstrates that light cannot be explained purely as a wave phenomenon. Comptons work convinced the scientific community that light can behave as a stream of particles (photons) whose energy is proportional to the frequency. The change in wavelength of the scattered photon is given by: Where: L = wavelength of incident x-ray photon l = wavelength of scattered x-ray photon H = Plancks Constant: The fundamental constant equal to the ratio of the energy E of a quantum of energy to its frequency v: E=hv. me = the mass of an electron at rest C = the speed of light Q = The scattering angle of the scattered photon The applet below demonstrates Compton scattering as calculated with the Klein-Nishina formula, which provides an accurate prediction of the angular distribution of x-rays and gamma-rays that are incident upon a single electron. Before this formula was derived, the electron cross section had been classically derived by the British physicist and discoverer of the electron, J.J. Thomson. However, scattering experiments showed significant deviations from the results predicted by Thomsons model. The Klein-Nishina formula incorporates the Breit-Dirac recoil factor, R, also known as radiation pressure. The formula also corrects for relativistic quantum mechanics and takes into account the interaction of the spin and magnetic moment of the electron with electromagnetic radiation.Quantum mechanics isa system of mechanics based on quantum theory to provide a consistent explanation of both electromagnetic wave and atomic structure. The applet shows that when a photon of a given energy hits an atom, it is sometimes reflected in a different direction. At the same time, it loses energy to an electron that is ejected from the atom. Theta is the angle between the scattered photon direction and the path of the incident photon. Phi is the angle between the scattered electron direction and the path of the incident photon. Derivation of the scattering formula A photonÃŽÂ ³with wavelengthÃŽÂ »is directed at an electronein an atom, which is at rest. The collision causes the electron to recoil, and a new photonÃŽÂ ³Ãƒ ¢Ã¢â€š ¬Ã‚ ²with wavelengthÃŽÂ »Ãƒ ¢Ã¢â€š ¬Ã‚ ²emerges at angleÃŽÂ ¸. Leteà ¢Ã¢â€š ¬Ã‚ ²denote the electron after the collision. From theconservation of energy, Compton postulated that photons carry momentum;-9-2[3]thus from theconservation of momentum, the momenta of the particles should be related by Assuming the initial momentum of the electron is zero. The photon energies are related to the frequencies by Wherehis thePlanck constant. From therelativistic energy-momentum relation, the electron energies are Along with the conservation of energy, these relations imply that Then From the conservation of momentum, Then by making use of thescalar product, Thus The relation between the frequency and the momentum of a photon ispc=hf, so Now equating 1 and 2, Then dividing both sides by 2hffà ¢Ã¢â€š ¬Ã‚ ²mec, SincefÃŽÂ »=fà ¢Ã¢â€š ¬Ã‚ ²ÃƒÅ½Ã‚ »Ãƒ ¢Ã¢â€š ¬Ã‚ ²=c, Detector characteristics Even large Compton-scatter telescopes have relatively small effective areas. This is because only a small number of the incident gamma-rays actually Compton scatter in the top level. So even if an instrument like COMPTEL has a geometric area of several thousand cm2, the effective area (weighted for the probability of an interaction) is a few tens of cm2. Energy resolution is fairly good for these detectors, typically 5-10% This is limited by uncertainties in the measurements of the energy deposited in each layer. Compton scatter telescopes have wide fields-of-view and can form imageseven though the so-called point spread function (the probability that an event came from a certain area on the sky) is a ring. Applications Compton scattering is of prime importance toradiobiology, as it is the most probable interaction of gamma rays and high energy X rays with atoms in living beings and is applied inradiation therapy.3[4] In material physics, Compton scattering can be used to probe thewave functionof the electrons in matter in the momentum representation. Compton scattering is an important effect ingamma spectroscopywhich gives rise to theCompton edge, as it is possible for the gamma rays to scatter out of the detectors used.Compton suppression is used to detect stray scatter gamma rays to counteract this effect. Inverse Compton scattering Inverse Compton scattering is important inastrophysics. InX-ray astronomy, theaccretion disksurrounding ablack holeis believed to produce a thermal spectrum. The lower energy photons produced from this spectrum are scattered to higher energies by relativistic electrons in the surroundingcorona. This is believed to cause the power law component in the X-ray spectra (0.2-10 keV) of accreting black holes. The effect is also observed when photons from thecosmic microwave backgroundmove through the hot gas surrounding agalaxy cluster. The CMB photons are scattered to higher energies by the electrons in this gas, resulting in theSunyaev-ZelHYPERLINK http://en.wikipedia.org/wiki/Sunyaev-Zeldovich_effectHYPERLINK http://en.wikipedia.org/wiki/Sunyaev-Zeldovich_effectdovich effect. Observations of the Sunyaev-Zeldovich effect provide a nearly redshift-independent means of detecting galaxy clusters. Some synchrotron radiation facilities scatter laser light off the stored electron beam. This Compton backscattering produces high energy photons in the MeV to GeV rangesubsequently used for nuclear physics experiments. Future developments Current research on Compton telescopes is emphasizing ways of tracking the scattered electron. By measuring the direction of the scattered electron in the top level, a complete solution for the incoming trajectory of the cosmic gamma-ray can be found. This would allow Compton telescopes to have more conventional data analysis approaches since the event circle would no longer exist.

The Wedding :: essays research papers

  Ã‚  Ã‚  Ã‚  Ã‚  In â€Å"The Wedding,† by Dorothy West, the major development I saw was in the character of Shelby. From the beginning till the end, the character changes and deals with many changes. Throughout the novel Shelby knows what she wants, knows she never gave a black a chance, and then decides whom she will marry.   Ã‚  Ã‚  Ã‚  Ã‚  At the beginning of the novel, Shelby is well focused and knows what she wants. She doesn’t care of what others think. Shelby stays focused on what going to take place and continues with the wedding. Many of her relative’s tries to talk her out of the marriage between her and the white-man, Meade. Although, she did have a little feeling for Lute.   Ã‚  Ã‚  Ã‚  Ã‚  Towards the middle of the novel, Shelby seems to feel a little confused and doesn’t really know what she wants. What people have been telling her seems to be sinking in. She begins to feel a little confused on what she really wants. Especially after the argument between her and her father, Clark. She expected him to support her, yet he also turns his back on her. At this time she feel confused and doesn’t know what to think or what to do. A talk with Liz, Shelby’s sister, convinces her to give a black a chance. Liz explains to Shelby on how she will have to live with her knowing she didn’t give a black a chance. It might come back to haunt her later.   Ã‚  Ã‚  Ã‚  Ã‚  Shelby decides to give the black a chance and decides see Lute. She feels good about seeing Lute, giving her a new sensation, a new feeling. Things seem to be okay and she is almost convinced of not marring Meade. Shelby gives Lute the idea she likes him and want to marry him. Right when Shelby is beginning to feel for Lute, he blows it when he decides to fight with his wife for a divorce. Shelby then is convinced of who she wants to marry.   Ã‚  Ã‚  Ã‚  Ã‚  Toward the end of the novel, Shelby is convinced and decides whom she really wants to marry. She decides to stick with her original plans and marries Meade.

Kantian Ethics Essay

Kant’s thought induced in philosophy what he himself christened ‘a Copernican revolution’, central to which was his ethical theory. Previous ethical theories had attempted to ground ethics in metaphysical or theological conceptions of â€Å"the good† or to base morality on human happiness as the final goal. For Kant, not only were conceptions of â€Å"the good† inaccessible to human thought, but any definition of human happiness could not be established and therefore used as a moral foundation. Instead he turned his moral thought to human nature as based within practical reason, and the moral principle he names the categorical imperative. This he defines according to the mottos ‘Act only on that maxim which you can at the same time will to be a universal law’ (Kant, [1785] 1948, p. 421) as well as ‘treat humanity†¦never simply as a means, but always at the same time as an ends’ (Kant, [1785] 1948, p. 429). With respect to the former, for example, the act of telling a lie would not be considered morally appropriate insofar as the individual telling the lie would not be able to will that all individuals in similar situations act in the same way. In order to function properly, society must operate within a contract of trust in which persons are able to assume a relative amount of truth and trustworthiness in their fellow citizens; otherwise human communication would inevitably collapse and civil society would prove unsustainable. Central to the categorical imperative is Kant’s notion of autonomy. Autonomy is defined as the individual’s freedom from external influences in his or her dutiful choice of the morally right. This is contrasted to heteronomy, in which the individual desires to do what is good for other reasons than simply the good itself. The connection between these concepts and the categorical imperative is clear: the imperative provides a deontological framework in relation to which and through which an autonomous individual may act ethically. If the moral agent follows the imperative for its own sake (i. e. in order to do his or her duty) and not for external reasons, then he or she, per definition, is acting freely and autonomously. Although Kant offers an insightful framework for morality, the picture of ethics he paints with respect to duty and autonomy is unfortunately inadequate to describe the human experience of morality. In the Groundwork in the Metaphysics of Morals, duty is given such great privilege over other human faculties that it is possible to think that Kant sees value in little else: ‘an action done out of duty has its moral worth, not from any purpose it may subserve, but from the maxim according to which it is determined on; it depends not on the effecting any given end, but on the principle of volition singly’ (Kant, [1785] 1836, p. 9). Of course, duty plays a crucial role in any moral act. For example, I may refrain from telling a lie to my wife because I have a duty—grounded in our wedding vows—to be honest with her. However, duty becomes a problem in our relationship if it serves the sole or most important reason for moral action: if I only act ethically toward my wife because I feel the need to grin and bear my duty, then our relationship will likely lack life and that which would make it a thriving partnership. Ethics incorporates more than duty, such that I do not simply do my duty to my wife for duty’s sake alone, but I also act ethically out of love, joy or perhaps even spontaneity. To restrict ethical behaviors to such a strict deontology unfairly limits the manifold and complicated ways in which humans practice ethics and relate to others individuals in a human moral framework. References Kant, Immanuel (1948). Groundwork of the Metaphysics of Morals. (H. J. Paton, Trans. ). London: Hutchinson. (Original work published 1785, and published in a collection in 1903; page references to this edition). Kant, Immanuel (1836). The Metaphysics of Ethics. (John William Semple, Trans. ). Edinburgh: Thomas Clark. (Original work published 1785).

Free Movement of Persons Within the European Union essays

Free Movement of Persons Within the European Union essays Free movement of persons rights can be seen as a tiered level of packages rotating around the fundamental concept of the worker. Rights and obligations arise out of the basic need to ensure the free movement of one of the main factors of production in the community. Illustrate this statement with case law and an analysis of the main regulation in this field. In what areas does the link with the worker concept no longer need to be so strong? Freedom of movement for persons and the abolition of controls at internal frontiers forms part of a wider concept, that of the internal market, in which it is not possible for internal frontiers to exist or for individuals to be hampered in their movements. The concept of the free movement of persons has changed in meaning since its inception. The first provisions on the subject referred merely to the free movement of individuals considered as economic agents, either as employees or providers of services. The original economic concept has gradually widened to take on a more general meaning connected with the idea of Union citizenship, independent of any economic activity or distinctions of nationality. Article 2: The Union shall set itself the following objectives (...)to maintain and develop the Union as an area of freedom, security and justice, in which the free movement of persons is assured in conjunction with appropriate measures with respect to external border controls, asylum, immigration and the prevention and combating of crime, Article 14 ECT: Establishing the internal market including the free movement of persons. The internal market shall comprise an area without internal frontiers in which the free movement of goods, persons, services and capital is ensured in accordance with the provisions of this Treaty. Article 18 ECT: Union citizens have the right to move and reside freely within the territory of the Member States. Every citizen of the Union shall h...

3 Reasons Quitting Might Be the Right Thing to Do

3 Reasons Quitting Might Be the Right Thing to Do The world is full of inspirational posters, coffee mugs, and bumper stickers telling us not to be quitters. But that kind of blanket dogma- black-and-white in a world of grey- can be hurtful on occasions when giving up might actually be the best idea. Here are three reasons why we think this advice doesn’t always have to be the final word. 1. It  can lead you to the path you really wantIt’s all well and good to say â€Å"winners never quit and quitters never win,† but what if you’ve devoted yourself to the wrong pursuit and quitting could lead you to a better one- where you could actually win and not just slog away forever because you’ve been told you’d be weak or lazy if you quit?If you’re on the wrong track, and you know it, sometimes quitting is the braver, nobler thing to do. And it just might be the only route to winning in the end. So have the courage to take stock of where you are and what you’re doing.2. Sometimes,   you’re just truly unhappyThere are a ton of cognitive biases that already predispose us against quitting. Like the sunk cost fallacy (â€Å"I’ve already spent so much on this hobby,† or â€Å"I’ve wasted so much of my life playing the tuba, so I can’t switch to building miniature boats†) or our bias towards the status quo (â€Å"I may have it rough now, but the unknown could be even worse†). Not to mention loss aversion and the need to hold on to whatever gains we’ve made at all costs. But none of these are good reasons to stick it out in bad relationships or careers. The last thing we need is some smarmy â€Å"Never give up† slogan making us feel even worse about our prospects.3. You  can set an example  and be an inspirationQuitting is considered weak, and quitters a failure. But we should buck this trend. Wouldn’t it be better to encourage people to be more mindful about what they do? And to check in from t ime to time to see whether they should still be doing it?Next time you notice someone spewing platitudes on Facebook about quitters or inspirational gifs about never giving up, take a moment to disagree. That advice can keep people from being their best selves, and can actually be harmful when wielded willy-nilly.

Client evaluation for Be Good To Go Research Paper

Client evaluation for Be Good To Go - Research Paper Example The company produces a nutritional health supplements that are geared towards helping people who travel to avoid constipation. Constipation among travelers is a common thing and many people who travel for relatively long distances using any means whether it is train, air, road or even water (ship) suffer from constipation upon reaching their destination (Westen 89). With the Be Good to Go products the traveler can travel safely knowing that they will reach to their destination and even further without having to fear about the issue of constipation. The products are capsules that people who are travelling can take. They come in pairs, one to be taken in the morning and the other in the evening after the parson has reached his or her destination. The mission of the firms is to make sure that people can travel contrary and without having to fear the age old problem of constipation. They achieved this by researching the issue and developing a product that when used properly will help the users to deal with the issue of traveler constipation. For Be Good to Go, it is almost hard to identify which industry or sector to place it. The first is that it not a public firm and scant information has been provided about the firm. However, given the nature of the products that the firm provides to its customers, it is only necessary to place it in the health and nutrition supplement industry. This industry has been regarded as the growth industry with regard to the fact that it is has a fast growing industry that will continue to grow at a very fast rate. The size of the Be Good to Go within this industry can be seen to be both big and small due t two main reasons. First, Be Good to Go has a unique sector in this industry, a sector which is a niche that not many firms have ventured into. In this regard, within this industry, Be Good to Go is a

POL 102 POLICY PAPER Essay Example | Topics and Well Written Essays - 250 words

POL 102 POLICY PAPER - Essay Example The policy on Africa and all African related matters is a policy that has been indoctrinated in the modus operandi of many developed nations. This is because Africa is a strategically significant country to the western world. The well-endowed governments all over the world having realized this and have been actively engaged in Africa’s affairs (Bender 15). This includes the social, political, economic and to some extent the cultural affairs. Many African countries have been assisted by the developed nations to revive their leadership, boost their economies, and solve internal wrangles. This policy was created with honorable intentions. However, its misuse is particularly evident in many African states all over the world. The policy has been manipulated to act as a bargaining chip for the western nations (Bender 47). It is necessary for the government to intervene in African states without expecting them to give something back. This aid has plunged many African countries into more darkness. The policy should be used to assist the African continent and the many problems it encounters. It should not be used as a bargaining block. Many historical injustices in Africa would have been avoided had the national policy on African related matters been applied to those countries. It is likely that the government is bound to accept the strengthening of this policy. This is because nations are demanding accountability and transparency from the government when exercising the policy in African states (Bender 51). Bender, G. J., Coleman, J. S., and Sklar, R. L. African Crisis and the US Foreign Policy. California: University of California Press, 2008. Web.