The American Imperialism free essay sample

DBQ Imperialism: To what extent was late nineteenth-century and early twentieth-century United States expansionism a continuation of past United States expansionism and to what extent was it a departure? By the year 1901, the United States possessed the third-largest navy in the world, a considerable overseas empire, and a burgeoning reputation as a world power. It had acquired this international precedence through its involvement in the fervent imperialism of the era; the rapid expansion, colonization, and competition that was occupying the most influential nations of the world, including Britain, France, Germany, and Japan. America’s new found role as a colonial power was not, however, a sudden development. Whereas the United States expansionism of the late nineteenth- and early twentieth-centuries was a clear continuation of the social and cultural principles that had fueled the nation’s past expansionism, it was to a greater degree a departure from the methods of the past through its pursuit of new economic and political motives. We will write a custom essay sample on The American Imperialism or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page American imperialism of the late 1800s and early 1900s demonstrated the same cultural and social justification of previous expansionism. The original doctrine of Manifest Destiny, which emerged in the 1840s to accompany westward continental expansion, advocated a belief that America was destined by God to expand its borders across the continent in order to spread the blessings of liberty. As Senator Albert J. Beveridge explicates in his 1900 speech to 56th Congress (Doc. E), this belief was equally influential in later imperial America; he expresses the Americans’ self-recognition as God’s chosen people, a race not only blessed, but bound by a holy duty to enlighten the rest of the world through their own expansion. This was the sentiment of â€Å"The White Man’s Burden†, described in Rudyard Kipling’s 1899 poem of this title, which invoked the social responsibility of the American race to elevate the primitive peoples of the earth. In the past, this duty had been attempted by the Christian missionaries’ permeation of the Indian tribes of the west, and was continued at the turn of the nineteenth century by the United States’ alleged efforts to civilize the inhabitants of foreign territory. Josiah Strong reaffirmed this ethnocentricity in his book Our Country: Its Possible Future and Its Present Crisis (Doc. B) as he described the holy mission of the Anglo-Saxon race to spread civil liberty and Christianity throughout continents across the globe. He thereby justified American imperialism with an assertion of cultural and racial superiority that had been a motivation of American expansion since the early nineteenth century. Although expansionism around the year 1900 shared some similar motivation with that of earlier decades, it was to a greater degree the result of new economic and political pursuits. Past expansion had involved annexing adjacent territory contiguous with the existing states that enabled the spread of American settlement; it was utilized for the spread of agriculture and the American population, and all acquired territory was intended to ultimately become states. Contrastingly, new territory in the age of imperialism was acquired with the economic intent of use as a colony: a provider of raw materials and markets for the products of industrialism. By denying citizenship to the inhabitants of the territory of the Philippines in the Insular Case Downes v. Bidwell (Doc. H) the Supreme Court demonstrated that the Constitution did not â€Å"follow the flag†, thereby proving that the United States had no intention of granting new territories equal status to states; they would instead be colonies serving American economic interests that contrasted with the settlement-based expansion of past decades. A further deviation from past expansionism that served as a political motivation of imperialism was the United States’ attempt to fill a role as a world power. This entailed competition with other nations in an imperialist race to claim foreign territory. In his 1899 book The Interest of America in Sea Power (Doc. C), Alfred T. Mahan expressed the need for America to prevent foreign acquisition of ideal territories that would serve American economic interests. He further mentioned the pressure that other expanding empires were exerting upon the United States to acquire crucial territories before another power did. Jingoists Henry Cabot Lodge and Theodore Roosevelt answered this demand by supporting entrance into the Spanish-American war, primarily to acquire new territory; Roosevelt ordered the taking of Manila Bay from Spain’s Philippine territory the moment war was declared in 1898. As president of the United States, Roosevelt would also be a proponent of America’s political dominance. He expressed in his Annual Message to Congress (Doc. F) in 1904 the responsibility of the United States to monitor and maintain the social and political stability of all nations in the Western Hemisphere. He compared his nation to an international police force that would inevitably dominate the affairs of all Latin American nations. This political motivation was clearly a development new to American imperialism, since past expansionism had only extended the country’s borders and maintained its policy of isolationism. The early twentieth century heralded an era of American expansionism that broke with past principles in its pursuit of economic and political interests, while it maintained cultural and social incentives of past continental expansion. As the United States began to acquire a colonial empire however, it became apparent that the allegedly noble social motives of Manifest Destiny and the spread of liberty merely served to justify the true secular intentions beneath imperialism: a desire for commercial gain and international power. It was ultimately a pursuit of these self-serving interests that fueled American imperialism and catapulted the nation to a position of dominance.

How Santas Reindeer Got Their Names

How Santa's Reindeer Got Their Names If you ask the average American to name Santas reindeer, the first name to pop up will probably be  Rudolph  (the Red-Nosed Reindeer). The next two would no doubt be  Donner  and  Blitzen. But is this correct? And where did these names come from? Origin of Reindeer Names The popular Christmas song  Ã¢â‚¬Å"Rudolph the Red-Nosed Reindeer† was a 1949 hit tune sung and recorded by Gene Autry and based on a character originally created by a marketing team for Montgomery Ward in 1939. The lyrics were written by  Johnny Marks, who borrowed most of the reindeer names from the classic 1823 poem â€Å"A Visit from Saint Nicholas† (more commonly known as â€Å"Twas the Night before Christmas†) by Major Henry Livingston, Jr. (Historically,  Clement Clarke Moore has been credited for the poem, but most scholars now believe Livingston to have been the poet.) The original poem refers to â€Å"eight tiny reindeer† (Rudolph actually makes it nine tiny reindeer) and names them: â€Å"Now Dasher! now, Dancer! now Prancer and Vixen!/On, Comet! on, Cupid! on Dunder and Blixem!† Later Versions Dunder and Blixem? Youve always heard Donner and Blitzen, right? The former were Dutch names written into the poem by Livingston. Only in later versions, modified by Moore in 1844, were the two names changed to German:  Donder  (close to  Donner, thunder) and  Blitzen  (lightning), to better rhyme with Vixen. Finally, for some reason, in the song â€Å"Rudolph the Red-Nosed Reindeer† Marks turned Donder into Donner. Whether Marks made the change because he knew German or because it just sounded better is uncertain.* In any event, there is certainly some logic in using German  Donner  and  Blitzen  (thunder and lightning) for the names. Since 1950 or so, the two reindeer names have been  Donner  and  Blitzen  in both â€Å"Rudolph the Red-Nosed Reindeer†Ã‚  and the â€Å"A  Visit  from Saint Nicholas.

Giardiasis Research Paper Example | Topics and Well Written Essays - 1000 words

Giardiasis - Research Paper Example Its existence in beavers informed the alternative name. Van Leeuwenhoek discovered Giardia in the year 1681, in the parasite’s trophozoite stage, though Giardia also exists in as cyst but Lambl developed more information on the parasite in the year 1959. The parasite was however believed to a non-toxic parasite until towards the year 1980 when it was known to cause diarrhea. The cyst stage of the parasite is a domant stage that allows Giardia to survive even in hostile environments. At this stage, the parasite can survive under cold temperatures, as cold as 80C. Giardia is common in water bodies such as streams and lakes (Chandlee, Clarke, Wisti, and Zucker, n.d.). Its primary habitant is the intestines of human beings and those of other animals and it is normally discharged in feces, and due to its ability to survive in its cyst form, can survive on or under the earth’s surface, and in water (The Centers for Disease Control and Prevention, 2011). In the United States, the infection is more prevalent among children between zero and 10 years old and adults between 35 and 49 years. Incidence rate also increased from the year 2009 to the year 2010, suggesting an increasing trend. Change in incidence rate by gender reflected this and incidence rate increased among Asians and Blacks but decreased among Native Americans and Whites. A total 19403 cases were reported in the year 2009 while 19888 cases were reported in the year 2010. The infection is also more prevalent in the northern region of the nation than in other regions and state incidence rates ranged from 2.6 cases per 100000 population to 29.6 cases per 100000 population (Yoder, Gargano, Wallace, and Beach, 2012). Globally, the infection is more prevalent in developing countries than it is in developed countries. While infection rates in developed countries such as in

PRESENTATION Essay Example | Topics and Well Written Essays - 750 words

PRESENTATION - Essay Example 7 9.What are you doing to ensure the validity of your research? 7 10.What do they anticipate will be gained through your research? 8 References 9 1. Why have you chosen to base your research on this company/facility/organisation/etc? The major objective of the proposed research is to highlight the consequences of staff training programmes in an organisation. The study will focus on staff training programmes that are implemented by McDonald’s in its global business operations. An effective staff training program can be beneficial for McDonald’s in order to avoid the increasing risks and threats that can arise in various phases within the marketplace. Moreover, it can also be considered as one of the major strategic tools for the organisation in order to achieve competitive advantage in global marketplace (Pranicevic & et. al., 2011). ). From the perspective of McDonald’s, the food chain retail organisation significantly implements effective training and learning p rograms for the employees in various regions of socially, culturally as well as linguistically diversified markets. Therefore, the organisation can be recognised as one of the major fast-food chain retailers across the various regions of the world. 2. ... ll as with the increasing number of competitors in the hospitality and food chain industry, employee training and development programs have become an essential step for the modern organisations in order to maintain their sustainability. In the present day context, organisations frequently employ training programs for the employees in order to educate them regarding effective steps that can be followed by them while dealing with the consumers. Therefore, an assessment of the core concepts that are utilised by a globally leading company, McDonald’s in this context can facilitate to recognise the value of staff training in the organisational context in both short and long run (Pranicevic & et. al., 2011). 3. What are your main literature sources and how have you located and accessed these? In the context of this proposed research, the study would be conducted through assessing various numbers of journals and books that are written by different authors. Moreover, in order to incre ase the effectiveness and suitability of this research, the proposed study would be evaluated through collecting information from primary sources including company annual reports, by conducting interviews and through questionnaire survey with the consumers and employees of McDonald’s. 4. What is the overall aim of your proposal and why? Identifying and highlighting the major effects of staff training in McDonald’s in order to develop the experiences of the global customers of the company’s fast-food retail chain segment is the major objective of this research. Moreover, recognizing various types of innovative and exceptional business strategies that are executed by McDonald’s in its effective staff training initiatives is also a major aim of the proposed research. The recognised aims of

C Programming Essay Example | Topics and Well Written Essays - 750 words

C Programming - Essay Example C truly is much more of a â€Å"programming environment† than just a language. Using this environment, a single developer can quickly create a simple application; a team of developers can create a sophisticated, distributed application. The main reason why C is so popular and powerful is the same reason behind the success of Windows. Microsoft took a complex technology (writing computer programs) and made it easier to use through a graphical interface. Suppose you have to write a program for your company. In a visual programming environment, you can quickly design the windows that the user sees by drawing and arranging them just as you would lay out elements for a newspaper. Arithmetic operators These are the simple operators used in daily mathematics. These include the addition ‘+’ operator, subtraction ‘-’ operator, multiplication ‘*’ operator, division ‘/’ operator and the modulus ‘%’ operator.

History And Fundamental Concept Of Acoustic Music Essay

History And Fundamental Concept Of Acoustic Music Essay Acoustics is the study of the physical characteristics of sounds. Its deal with things like the frequency, amplitude and complexity of sound waves and how sound waves interact with various environments. It can also be refer casually and generally to the over-all quality of sound in a given place. Someone might say in a non-technical conversation: I like to perform at Smith Hall; the acoustics are very brights.   From the everyday sounds of speech, the hum of appliances, to the sounds caused by wind and water, we are immersed in an ocean of sounds. Yet, what is sound, and how do we hear it? Why do two instruments playing the same note sound different? In this lab you will learn the basics of the answers to these questions. To answer the later question, we will analyze sound as an audio engineer would, through a technique called harmonic analysis. Harmonic analysis allows sound to be understood from a quantitative perspective. Also, we will come to an understanding of why the way a computer analyses sound is similar to how our ears analyse sound. I will start this genre presentation by introducing the genre acoustic music. It isnt really a genre, as music played with acoustic instruments can sound very different, but I chose to call the post this, as acoustic music have many similarities. If you like these songs, you should really check out  Bedtime Tunes, which is a site only with songs like these. So without further ado, here are 11 songs with acoustic guitars, pianos, strings and beautiful voices: First here is Antony Hearty with his band  Antony and the Johnsons. Antony Hegarty is a very special person, he is transgendrous, and his voice is absolutely amazing. Unfortunately I havent seen him live, but Ive heard that almost all of the audience comes out from the concert crying Or Acoustics (from Greek pronounced acoustics meaning of or for hearing, ready to hear) is the science that studies sound, in particular its production, transmission, and effects. Sound can often be considered as something pleasant; an example of this would be music. In that case a main application is room acoustics, since the purpose of room acoustical design and optimisation is to make a room sound as good as possible. But some noises can also be unpleasant and make people feel uncomfortable. In fact noise reduction is a major challenge, particularly within the transportation industry as people are becoming more and more demanding. Furthermore ultrasounds also have applications in detection, such as sonar systems or non-destructive material testing. 2. History of acoustic If he first mentioned the Acoustique Art in his  Advancement of Learning  (1605), Francis Bacon (1561-1626) was drawing a distinction between the physical acoustics he expanded in the  Sylva Sylva rum  (1627) and the harmonics of the Pythagorean mathematical tradition. The Pythagorean tradition still survived in Bacons time in the works of such diverse people as Gioseffo Zarlino (1517-1590), Renà © Descartes (1596-1650), and Johannes Kepler (1571-1630). In Bacons words: The nature of sounds, in some sort, [hath  been with some  diligence  inquired,] as far as concerneth music. But the nature of sounds in general hath been superficially observed. It is one of the subtlest pieces of nature. Bacons Acoustique Art was therefore concerned with the study of immusical sounds and with experiments in the migration in sounds so that the harnessing of sounds in buildings (architectural acoustics) by their enclosure in artificial channels inside the walls or in the environment (hydraulic acoustics). Aim of Baconian acoustics was to catalog,  quantify, and shape human space by means of sound. This stemmed from the  echometria,  an early modern tradition of literature on echo, as studied by the mathematicians Giuseppe Biancani (1566-1624), Marin Mersenne (1588-1648), and Daniello Bartoli (1608-1685), in which the model of optics was applied in acoustics to the behaviour of sound. It was in a sense a historical  antecedent  to Isaac Newtons (1642-1727) analogy between colours and musical tones in  Upticks  (1704). Athanasius Kirchers (1601-1680)  Phonurgia Nova  of 1673 was the outcome of this tradition. Attacking British acoustics traditions, Kirsches argued that the origin of the Acoustical Art lay in his own earlier experiments with sounding tubes at the Collegio Romano in 1649 and sketched the ideology of a Christian baroque science of acoustics designed to dominate the world by exploiting the boundless  powers of sound 17th-century empirical observations and mathematical explanations of the simultaneous vibrations of a string at different frequencies were important in the development of modern experimental acoustics. The earliest contribution in this branch of acoustics was made by Mersenne, who derived the mathematical law governing the physics of a vibrating string. Around 1673 Christian Huygens (1629-1695) estimated its absolute frequency, and in 1677 John Wallis (1616-1703) published a report of experiments on the overtones of a vibrating string. In 1692 Francis Roberts (1650-1718) followed with similar findings. These achievements paved the way for the 18th-century  acoustique  of Joseph Sauveur (1653-1716) and for the work of Brook Taylor (1685-1731), Leonhard Euler (1707-1783), Jean Le Rond d Alembert  (1717-1783), Daniel Bernoulli (1700-1782), and Giordani Riccati (1709-1790), who all attempted to determine mathematically the fundamental tone and the overtones of a  sonorous  body. Modern experimental acoustics sought in nature, a physical law of the sounding body, the perfect harmony that in the Pythagorean tradition sprang from the mind of the geometrizing God. Experimental epistemology in acoustics also influenced the studies of the anatomy and physiology of hearing, especially the work of Joseph-Guichard Duverney (1648-1730) and Antonio Maria Valsalva (1666-1723), that in the 19th century gave rise to physiological and psychological acoustics. 3. Fundamental concepts of acoustics The study of acoustics revolves around the generation, propagation and reception of mechanical waves and vibrations. The steps shown in the above diagram can be found in any acoustical event or process. There are many kinds of cause, both natural and volitional. There are many kinds of transduction process that convert energy from some other form into acoustic energy, producing the acoustic wave. There is one fundamental equation that describes acoustic wave propagation, but the phenomena that emerge from it are varied and often complex. The wave carries energy throughout the propagating medium. Eventually this energy is transduced again into other forms, in ways that again may be natural and/or volitionally contrived. The final effect may be purely physical or it may reach far into the biological or volitional domains. The five basic steps are found equally well whether we are talking about an earthquake, a submarine using sonar to locate its foe, or a band playing in a rock concert. The central stage in the acoustical process is wave propagation. This falls within the domain of physical acoustics. In  fluids, sound propagates primarily as a pressure wave. In solids, mechanical waves can take many forms including  longitudinal waves,  transverse HYPERLINK http://www.answers.com/topic/transverse-wavewaves  and  surface waves. Acoustics looks first at the pressure levels and frequencies in the sound wave. Transduction processes are also of special importance. 4. Application of Acoustics The science of sound and hearing. This treats the sonic qualities of rooms and buildings, and the transmission of sound by the voice, musical instruments or electric means. Voice is caused by vibration, which is communicated by the sound source to the air as fluctuations in pressure and then to the listeners ear-drum. The faster the vibration (or the greater its frequency) the higher the pitch. The greater the amplitude of the vibration, the louder the sound. Mostly musical sound consist not only of regular vibration at one particular frequency but also vibration at various multiples of that frequency. The frequency of middle C is 256 cycles per second (or Hertz, abbreviated Hz) but when one hears middle C there are components of the sound vibrating at 512 Hz, 768 Hz etc (see  Harmonics). The presence and relative strength of these harmonics determine the quality of a sound. The difference in quality, for example. between a flute, an oboe and a clarinet playing the same note is tha t the flutes tone is relatively pure (i.e. has few and weak harmonics), the oboe is rich in higher harmonics and the clarinet has a preponderance of odd-numbered harmonics. Their different harmonic spectra are caused primarily by the way the sound vibration is actuated (by the blowing of air across an edge with the flute, by the oboes double reed and the clarinets single reed) and by the shape of the tube. Where the players lips are the vibrating agent, as with most brass instruments, the tube can be made to sound not its fundamental note but other harmonics by means of the players lip pressure. The vibrating air column is only one of the standard ways of creating musical sound. The longer the column the lower the pitch; the players can raise the pitch by uncovering hole in the tubes. With that human voice, air is set in motion by means of the vocal cords, folds in the throat which convert the air stream from the lungs into sound; pitch is controlled by the size and shape of the cavities in the pharynx and mouth. For a string instrument, such as the violin, the guitar or the piano, the string is set in vibration by (respectively) bowing, plucking or striking; the tighter and thinner the string, the fasters it will vibrate. By pressing the string against the fingerboard and thus making the operative string-length shorter, the player can raise the pitch. With a percussion instrument, such as the drum or the xylophone, a membrane or a piece of wood is set in vibration by striking; sometimes the vibration is regular and gives a definite pitch but sometimes the pitch is indefinit e. In the recording of sound, the vibration patterns set up by the instrument or instruments to be recorded are encode by analogue (or, in recent recordings. digitally) in terms of electrical impulse. This information can then be stored, in mechanical or electrical form; this can then be decoded, amplified and conveyed to loudspeakers which transmit the same vibration pattern to the airs. The study of the acoustics of buildings is immensely complicated because of the variety of ways in which sound is conveyed, reflected, diffused, absorbed etc. The design of buildings for performances has to take account of such matters as the smooth and even representation of sound at all pitches in all parts of the building, the balance of clarity and blend and the directions in which reflected sound may impinge upon the audiences. The use of particular material (especially wood and artificial acoustical substances) and the breaking-up of surfaces, to avoid certain types of reflection of sounds, play a part in the design of concert halls, which however remains an uncertain art in which experimentation and tuning (by shifting surface, by adding resonators etc.) is often necessary. The term acoustic is sometimes used, of a recording or an instrument, to mean not electric: an acoustic recording is one made before electric methods came into use, and an acoustic guitar is one not electri cally amplified. 4.1 Theory of acoustic The area of physics known as acoustics is devoted to the study of the production, transmission, and reception of sound. Thus, wherever sound is produced and transmitted, it will have an effect some whereas, even if there is no one present to hear it. The medium of sound transmissions is an all-important, key factor. Among the areas addressed within the realm of acoustics are the production of sounds by the human sounds and various instrument, as like the reception of sound waves by the human ear. 5. Working concept of acoustic Sound waves are an example of a larger phenomenon known as wave motion, and wave motion is, in turn, a subset of harmonic motion-that is, repeated movement of a particle about a position of equilibrium, or balance. In the case of sound, the particle is not an item of matter, but of energy, and wave motion is a type of harmonic movement that carries energy from one place to another without actually moving any matter. Particles in waves experience  oscillation, harmonic motion in one or more dimensions. Oscillation itself involves little movement, though some particles do move short distances as they interact with other particles. Primarily, however, it involves only movement in place. The waves themselves, on the other hand, move across space, ending up in a position different from the one in which they started. A  transverse  wave forms a regular up-and-down pattern in which the oscillation is  perpendicular  to the direction the wave is moving. This is a fairly easy type of wave to visualize: imagine a curve moving up and down along a straight line. Sound waves, on the other hand, are  longitudinal  waves, in which oscillation occurs in the same direction as the wave itself. These oscillations are really just fluctuations in pressure. As a sound wave moves through a medium such as air, these changes in pressure cause the medium to experience alternations of density and rarefaction  (a decrease in density). It , in turn, produces vibrations in the human ear or in any other object that receives the sound waves. 5.1 Properties of Sound Waves 5.1.1 Cycle and Period The term cycle has a definition that varies slightly, depending on whether the type of motion being discussed is oscillation, the movement of transverse waves, or the motion of a longitudinal sound wave. In the latter case, a cycle is defined as a single complete  vibration. A period (represented by the symbol  T) is the amount of time required to complete one full cycle. The period of a sound wave can be mathematically related to several other aspects of wave motion, including wave speed, frequency, and  wavelength. 5.1.2 The Speed of Sound in Various Medium People often refer to the speed of sound as though this were a fixed value like the speed of light, but, in fact, the speed of sound is a function of the medium through which it travels. What people ordinarily  mean by the speed of sound is the speed of sound through air at a specific temperature. For sound travelling at sea level, the speed at 32 °F (0 °C) is 740 MPH (331 m/s), and at 68 °F (20 °C), it is 767 MPH (343 m/s). In the essay on  aerodynamics, the speed of sound for aircraft was given at 660 MPH (451 m/s). This is much less than the figures given above for the speed of sound through air at sea level, because obviously, aircraft are not flying at sea level, but well above it, and the air through which they pass is well below freezing temperature. The speed of sound through a gas is proportional to the square root of the pressure divided by the density. According to Gay-Lussacs law, pressure is directly related to temperature, meaning that the lower the pressure, the lower the temperature-and vice versa. At high altitudes, the temperature is low, and, therefore, so is the pressure; and, due to the relatively small gravitational pull that Earth exerts on the air at that height, the density is also low. Hence, the speed of sound is also low. It follows that the higher the pressure of the material, and the greater the density, the faster sound travels through it: thus sound travels faster through a liquid than through a gas. This might seem a bit surprising: at first  glance, it would seem that sound travels fastest through air, but only because we are just more  accustomed  to hearing sounds that travel through that medium. The speed of sound in water varies from about 3,244 MPH (1,450 m/s) to about 3,355 MPH (1500 m/s). Sound travels even faster through a solid-typically about 11,185 MPH (5,000 m/s)-than it does through a liquid. 5.1.3 Frequency Frequency (abbreviated  f) is the number of waves passing through a given point during the interval of one second. It is measured in Hertz (Hz), named after nineteenth-century German physicist Heinrich Rudolf Hertz (1857-1894) and a Hertz is equal to one cycle of oscillation per second. Higher frequencies are expressed in terms of  kilohertz  (kHz; 103  or 1,000 cycles per second) or  megahertz(MHz; 106  or 1 million cycles per second.) The human ear is capable of hearing sounds from 20 to approximately 20,000 Hz-a relatively small range for a mammal, considering that bats, whales, and dolphins can hear sounds at a frequency up to 150  kHz. Human speech is in the range of about 1 kHz, and the 88 keys on a piano vary in frequency from 27 Hz to 4,186 Hz. Each note has its own frequency, with middle C (the white key in the very middle of a piano keyboard) at 264 Hz. The quality of harmony or  dissonance  when two notes are played together is a function of the relationship between the frequencies of the two. Frequencies below the range of human  audibility  are called  infrasound, and those above it are referred to as  ultrasound. There are a number of practical applications for  ultrasonic  technology in medicine, navigation, and other fields. 5.1.4 Wavelength Wavelength (represented by the symbol ÃŽÂ », the Greek letter lambda) is the distance between a crest and the adjacent crest, or a trough and an adjacent trough, of a wave. The higher the frequency, the shorter the wavelength, and vice versa. Thus, a frequency of 20 Hz, at the bottom end of human audibility, has a very large wavelength: 56 ft. (17 m). The top end frequency of 20,000 Hz is only 0.67 inches (17 mm). There is a special type of high-frequency sound wave beyond ultrasound: hyper sound, which has frequencies above 107  MHz, or 10 trillion Hz. It is almost impossible for hyper sound waves to travel through all but the densest media, because their wavelengths are so short. In order to be transmitted properly, hyper sound requires an extremely tight molecular structure; otherwise, the wave would get lost between molecules. Wavelengths of visible light, part of the electromagnetic spectrum, have a frequency much higher even than hyper sounds waves: about 109  MHz, 100 times greater than for hyper sound. This, in turn, means that these wavelengths are incredibly small, and this is why light waves can easily be blocked out by using ones hand or a  curtain. The same does not hold for sound waves, because the wavelengths of sounds in the range of human audibility are comparable to the size of ordinary objects. To block out a sound wave, one needs something of much greater dimensions-width, height, and depth-than a mere cloth curtain. A thick concrete wall, for instance, may be enough to block out the waves. Better still would be the use of materials that absorb sound, such as cork, or even the use of machines that produce sound waves which destructively interfere with the offending sounds. 5.1.5 Amplitude and Intensity Amplitude is critical to the understanding of sound, though it is mathematically independent from the parameters so far discussed. Defined as the maximum displacement of a vibrating material, amplitude  is the size of a wave. The greater the amplitude, the greater the energy the wave contains: amplitude indicates intensity, commonly known as volume, which is the rate at which a wave moves energy per unit of a cross-sectional area. Intensity can be measured in watts per square meter, or W/m2. A sound wave of minimum intensity for human audibility would have a value of 10à ¢Ã‹â€ Ã¢â‚¬â„¢12, or 0.000000000001, W/m2. As a basis of comparison, a person speaking in an ordinary tone of voice generates about 10à ¢Ã‹â€ Ã¢â‚¬â„¢4, or 0.0001, watts. On the other hand, a sound with an intensity of 1 W/m2  would be powerful enough to damage a persons ears. 5.2 Real-Life Applications 5.2.1 Decibel Levels For measuring the intensity of a sound as experienced by the human ear, we use a unit other than the watt per square meter, because ears do not respond to sounds in a linear, or straight-line, progression. If the intensity of a sound is doubled, a person perceives a greater intensity, but nothing approaching twice that of the original sound. Instead, a different system-known in mathematics as a logarithmic scale-is applied. In measuring the effect of sound intensity on the human ear, a unit called the  decibel  (abbreviated dB) is used. A sound of minimal audibility (10à ¢Ã‹â€ Ã¢â‚¬â„¢12  W/m2) is assigned the value of 0 dB, and 10 dB is 10 times as great-10à ¢Ã‹â€ Ã¢â‚¬â„¢11  W/m2. But 20 dB is not 20 times as intense as 0 dB; it is 100 times as intense, or 10à ¢Ã‹â€ Ã¢â‚¬â„¢10  W/m2. Every increase of 10 dB thus indicates a  tenfold  increase in intensity. Therefore, 120 dB, the maximum decibel level that a human ear can endure without experiencing damage, is not 120 times as great as the minimal level for audibility, but 1012  (1  trillion) times as great-equal to 1 W/m2, referred to above as the highest safe intensity level. Of course, sounds can be much louder than 120 dB: a rock band, for instance, can generate sounds of 125 dB, which is 5 times the maximum safe decibel level. A gunshot,  firecracker, or a jet-if one is exposed to these sounds at a sufficiently close proximity-can be as high as 140 dB, or 20 times the maximum safe level. Nor is 120 dB safe for prolonged periods: hearing experts indicate that regular and repeated exposure to even 85 dB (5 less than a lawn  mower) can cause permanent damage to ones hearing. 5.3 Production of Sound Waves 5.3.1 Musical Instruments Sound waves are vibrations; thus, in order to produce sound, vibrations must be produced. For a stringed instrument, such as a guitar,  harp, or piano, the strings must be set into vibration, either by the musicians fingers or the mechanism that connects piano keys to the strings inside the case of the piano. In other woodwind instruments and horns, the musician causes vibrations by blowing into the mouthpiece. The exact process by which the vibrations emerge as sound differs between woodwind instruments, such as a  clarinet  or  saxophone  on the one hand, and brass instruments, such as a trumpet or  trombone  on the other. Then there is a drum or other percussion instrument, which produces vibrations, if not musical notes. 5.3.2 Electronic Amplification Sound is a form of energy: thus, when an automobile or other machine produces sound  incidental  to its operation, this actually represents energy that is lost. Energy itself is conserved, but not all of the energy put into the machine can ever be realized as useful energy; thus, the automobile loses some energy in the form of sound and heat. The fact that sound is energy, however, also means that it can be converted to other forms of energy, and this is precisely what a  microphone  does: it receives sound waves and converts them to electrical energy. These electrical signals are transmitted to an  amplifier, and next to a  loudspeaker, which turns electrical energy back into sound energy-only now, the intensity of the sound is much greater. Inside a loudspeaker is a  diaphragm, a thin, flexible disk that vibrates with the intensity of the sound it produces. When it pushes outward, the diaphragm forces nearby air molecules closer together, creating a high-pressure region around the loudspeaker. (Remember, as stated earlier, that sound is a matter of fluctuations in pressure.) The diaphragm is then pushed backward in response, freeing up an area of space for the air molecules. These, then, rush toward the diaphragm, creating a low-pressure region behind the high-pressure one. The loudspeaker thus sends out alternating waves of high and low pressure, vibrations on the same frequency of the original sound. 5.3.3 The Human Voice As impressive as the electronic means of sound production are (and of course the description just given is highly simplified), this technology pales in comparison to the greatest of all sound-producing mechanisms: the human voice. Speech itself is a highly complex physical process, much too involved to be discussed in any depth here. For our present purpose, it is important only to recognize that speech is essentially a matter of producing vibrations on the vocal cords, and then transmitting those vibrations. Before a person speaks, the brain sends signals to the vocal cords, causing them to  tighten. As speech begins, air is forced across the vocal cords, and this produces vibrations. The action of the vocal cords in producing these vibrations is, like everything about the miracle of speech,  exceedingly involved: at any given moment as a person is talking, parts of the vocal cords are opened, and parts are closed. The sound of a persons voice is affected by a number of factors: the size and shape of the sinuses and other cavities in the head, the shape of the mouth, and the placement of the teeth and tongue. These factors influence the production of specific frequencies of sound, and result in differing vocal qualities. Again, the mechanisms of speech are highly complicated, involving action of the diaphragm (a partition of muscle and tissue between the chest and  abdominal  cavities),  larynx, pharynx,  glottis, hard and soft palates, and so on. But, it all begins with the production of vibrations. 6. Propagation: Does It Make a Sound As stated in the introduction, acoustics is concerned with the production, transmission (sometimes called propagation), and reception of sound. Transmission has already been examined in terms of the speed at which sound travels through various media. One aspect of sound transmission needs to be reiterated, however: for sound to be propagated, there must be a medium. There is an age-old philosophical question that goes something like this: If a tree falls in the woods and there is no one to hear it, does it make a sound? In fact, the question is not a matter of philosophy at all, but of physics, and the answer is, of course, yes. As the tree falls, it releases energy in a number of forms, and part of this energy is manifested as sound waves. Consider, on the other hand, this rephrased version of the question: If a tree falls in a vacuum-an area completely  devoid  of matter, including air-does it make a sound? The answer is now a qualified no: certainly, there is a release of energy, as before, but the sound waves cannot be transmitted. Without air or any other matter to carry the waves, there is literally no sound. Hence, there is a great deal of truth to the tagline associated with the 1979 science-fiction film  Alien  : In space, no one can hear you scream. Inside an astronauts suit, there is pressure and an oxygen supply; without either, the astronaut would  perish  quickly. The pressure and air inside the suit also allow the astronaut to hear sounds within the suit, including communications via microphone from other astronauts. But, if there were an explosion in the vacuum of deep space outside the spacecraft, no one inside would be able to hear it. 7. Reception of Sound 7.1 Recording Earlier the structure of electronic  amplification  was described in very simple terms. Some of the same processes-specifically, the conversion of sound to electrical energy-are used in the recording of sound. In sound recording, when a sound wave is emitted, it causes vibrations in a diaphragm attached to an electrical  condenser. This causes variations in the electrical current passed on by the condenser. These electrical pulses are processed and ultimately passed on to an electromagnetic recording head. The magnetic field of the recording head extends over the section of tape being recorded: what began as loud sounds now produce strong magnetic fields, and soft sounds produce weak fields. Yet, just as electronic means of sound production and transmission are still not as impressive as the mechanisms of the human voice, so electronic sound reception and recording technology is a less magnificent device than the human ear. 8. How the Ear Hears As almost everyone has noticed, a change in altitude (and, hence, of atmospheric pressure) leads to a strange popping sensation in the ears. Usually, this condition can be overcome by swallowing, or even better, by  yawning. This opens the  Eustachian tube, a  passageway  that maintains atmospheric pressure in the ear. Useful as it is, the Eustachian tube is just one of the human ears many parts. The funny shape of the ear helps it to capture and  amplify  sound waves, which  pass-through  the ear canal and cause the  eardrum  to vibrate. Though humans can hear sounds over a much wider range, the optimal range of audibility is from 3,000 to 4,000 Hz. This is because the structure of the ear canal is such that sounds in this frequency produce  magnified  pressure fluctuations. Thanks to this, as well as other specific properties, the ear acts as an amplifier of sounds. Beyond the eardrum is the middle ear, an  intricate  sound-reception device containing some of the smallest bones in the human body-bones commonly known, because of their shapes, as the hammer, anvil, and stirrup. Vibrations pass from the hammer to the anvil to the stirrup, through the membrane that covers the oval window, and into the inner ear. Filled with liquid, the inner ear contains the semi-circular canals responsible for providing a sense of balance or orientation: without these, a person literally would not know which way is up. Also, in the inner ear is the  cochlea, an organ shaped like a  snail. Waves of pressure from the fluids of the inner ear are passed through the cochlea to the  auditory  nerve, which then transmits these signals to the brain. The basilar membrane of the cochlea is a particularly  wondrous  instrument, responsible in large part for the ability to discriminate between sounds of different frequencies and intensities. The surface of the membrane is covered with thousands of fibres, which are highly sensitive to disturbances, and it transmits information concerning these disturbances to the auditory nerve. The brain, in turn, forms a relation between the position of the nerve ending and the frequency of the sound. It also equates the degree of disturbance in the  basilar membrane  with the intensity of the sound: the greater the disturbance, the louder the sounds.

The Future of Computers in Education :: essays papers

The Future of Computers in Education CURRENT PROBLEMS OF EDUCATION It seems reasonable to begin a discussion of the future of computers in education with considerations of the current problems of education. Then we can direct our use of technology to improve education. I do not mean to imply that there would be universal agreement on these problems or that this list is exhaustive; but these serious problems deserve careful preliminary consideration in restructuring our educational systems. They are worldwide problems that affect all levels of education. I begin with what I regard as the root of many of the grand problems of today: the problem of population. The number of people on earth is growing rapidly with no sign that we will be able to stop this growth. Indeed, many powerful people and groups encourage this growth. Educators often do not see this as an educational problem, but I believe this view to be wrong. World Population: The Grand Problem At the beginning of this century, the population of the earth, after thousands of years of development of civilization, reached one billion people. At the beginning of the new century we will have about six billion people on earth, and this number continues to grow rapidly -- presently at ninety million people per year. A scenario from the United Nations gives the world population in 2150 as 694 billion, based on current growth rates in the different parts of the world.[1] This is very unlikely, but it shows the serious nature of the problem. I regard this rapid growth of population as the root problem on earth today, not just for learning but also for many other aspects of modern society. Attempts to control population in countries such as China and India have met with only partial success. In most of the world there is only an inadequate attempt at population control. A rapidly growing population means that with today’s methods of learning many people will receive no or inferior education. Schools and other educational institutions cannot handle, in their present mode, even in highly developed countries, the ever-increasing numbers of students, and they change only slowly. Very few of the people on earth receive an adequate education even today.