Friday, November 29, 2019

Ancient Greek Democracy that Still Makes People Strive for Perfection

Ancient Greek Democracy that Still Makes People Strive for Perfection Ancient Greece is often referred to as a cradle of the Western World. This is not just a smart metaphor, but a certain fact that can hardly be refuted.Advertising We will write a custom essay sample on Ancient Greek Democracy that Still Makes People Strive for Perfection specifically for you for only $16.05 $11/page Learn More Thus, Greek dreams of a perfect society where everyone (or at least the majority) is happy resulted in the creation of the first democracy in the world. This invention of humanity has had a great impact on the development of the human society. First, Greek cities were governed as any other kingdom in the ancient world. However, a number of uprisings made Ancient Greeks work out a unique political system. Thus, in the 6th century B.C. Greeks created the first democratic society. It is possible to understand the major principles of Ancient Greek democracy when considering the meaning of the very word democratic. Thus, the word consists o f two composites: demos and kratos. The first composite is translated as â€Å"the people† and kratos is translated as â€Å"power†, which gives us the following meaning: â€Å"the power of the people† (qtd. in Ober 3). Therefore, there was no single ruler in the country and there was no risk of tyranny. Basically, people discussed the problems and worked out specific solutions to the problems. Admittedly, it can be a bit naà ¯ve to think that the majority always benefitted as there were always elite groups that pursued their specific objectives. Nonetheless, needs of many people were taken into account and many people could enjoy basic rights. It is possible to state that the creation of such a democratic society was revolutionary. Of course, it had an enormous impact on the development of humanity. Notably, many societies are based on the principles of Greek democracy. Many European countries followed the example of Ancient Greece to create new better societi es. Thus, French Republic was based on major principles developed by ancient Greeks.Advertising Looking for essay on ancient history? Let's see if we can help you! Get your first paper with 15% OFF Learn More The USA can be regarded as one of the brightest examples of democratic societies. Undoubtedly, Americans used experience of French people and used the principles outlined in Ancient Greece. Apart from such significant political implications, democratic principles of Ancient Greece have become certain part of people’s consciousness. As far as I am concerned, I am also affected by the democratic principles. I think Ancient Greeks managed to outline major principles of a perfect and just society. More so, I think I have specific views on society due to the influence of Ancient Greece. I have heard of justice and equality from my childhood. Of course, these views date back to the ancient world. Now I think that people should take a stand whenever they may need. I think that people can find solutions if they start a proper discussion when they listen to each other. I also think that these principles have affected my life. For instance, I believe discussion is the most important thing in any human interaction. Thus, I always discuss issues and I never jump to conclusions. I try to consider all possible factors and take into account all opinions. Of course, some time ago I thought I developed such principles as I was so smart and just. However, I think I did not work out these ideas. I only adopted them. These ideas are in the air and people cannot but adopt them (or try to oppose to them). Most importantly, no one remains distant as these ideas are integrated in our universe. Ober, Josiah. â€Å"The Original Meaning of â€Å"Democracy†: Capacity to Do Things, not Majority Rule.† Constellations 15.1 (2008): 3-9. Print.Advertising We will write a custom essay sample on Ancient Greek Democracy that Still Makes People Strive for Perfection specifically for you for only $16.05 $11/page Learn More

Monday, November 25, 2019

The Change of Role of Women Essay Example

The Change of Role of Women Essay Example The Change of Role of Women Essay The Change of Role of Women Essay The Change of the Role of Women Women can hold up half the sky This famous quote was said by Mao Sedona, a man who understood and fought for women equality. In modern China, women can fully participate in all aspects of society. Their standard of living is on the rise. However, Chinese women did suffer a lot from Inequality In the past. Historically, the life of women was very difficult. They might not make It through as a baby. Sometimes a baby girl would be abandoned If her family didnt want her. Even If they were lucky. Most of them couldnt get education, and they shall obey their husbands for their hole life. They had no say In who they wanted to marry. As time progresses, womens life has surely gone better. There are lots of remarkable regress and at the same time progress during 1900 to 1997. In ancient China, since men were allowed to have multiple wives, many women were served as concubines. Women were considered as sexual partners and especially, tools for giving births. During Tang dynasty, Emperor Gao Z was thought to have 40,000 women in his palace just to ensure he had as many offspring as possible. Women werent allowed to receive education. They were supposed to only take care of their households for the rest of their lives. Also, there was custom for Chinese women was that they all had to bind their feet. Women was thought to be beautiful only when they had small feet. According to Han Quoin in Northern Chinas Shania province, the last Chinese woman that has her feet bound, she had her feet broken and bound when she was at only the age of two. It took her six months to get used to the pain and walk properly. In 1902, there was a ban on feet binding but it was thought to be ineffective since laws ere ignored and women still suffer from the pain. Even so, a minority of women had started to have the will to escape from this unfair life style. Dowager Empress Xix, was surely one of those brave people. She started as a concubine of the emperor, who slowly made her way up until she was in charge of China for forty-seven years. She passed away in 1908. She once considered herself as the most powerful and richest sovereign in the world. There were one big events during year 1912 to 1949, which is the World War II. It was a hard time for Chinese women. Many of them were detained by the Japanese army and forced Into prostitution. Those were called comfort women. They were abused and treated badly everyday. As stated In a book titled-Chinese Comfort Women, Recent research In China suggests that Chinese women accounted for about half of the estimated total of 400,000 victims of the military comfort women system. After the war, they were afraid to stand up for themselves since they were considered as disgraces to their family, rather than being taken care for. Even so, the good thing was that after the end of King Dynasty, women darted to fight for their rights. They would get education from universities. Many of them soon found their careers as teachers, writers, or even political activists. One of a famous inspiring Chinese women was Song Mining Ling, Mother of the Nation and the wife of Sun Hat San. After Mayos success, she had chosen to stay in China. Her goal had switched from freeing the People of China to gaining rights for women in organization which focused on the improvement of womens conditions. For instance, girls schools were set up to provide women education and skills to work, according to book doltishnesss movements in Twentieth-Century Taiwan. She was also founder of several welfare or civil right organizations in China. She was seemed as a significant figure of women empowerment in China. Theres also one huge debate in 1919, when there was a news of women committed suicide due to forced marriage. Mao Sedona described it as the rottenness of the marriage system and the darkness of the social system This shows that womens rights had slowly gain attentions and solutions by higher authorities and the public. During 1949-1976, when the Communist Party gained control of China, Mayos one of the important action was to improve Chinese womens conditions. In 1949,the women labor force rose to 44% in China. (great leap forward)Len 1950, there was a Land Reform Act. Its purpose was to improve the standard of living of the peasants in China through land redistribution. The Land Reform Act benefited women that they had the chance to own properties under their names. Due to a new marriage law established in 1950, unmarried, divorced, or widowed women could have the rights to hold land. Another event ring this time period was the Cultural Revolution (CRY). This is hard to identify as purely progress or regress. During the CRY, young people were told by Mao to form Red Guard units, whose Job was to criticize educated people. Yes, many women had faced violence, forced labor, or even death if they were considered as envoys China but at the same time, young women were encouraged to participate in the violence as Red Guard. Some of them were having the same rights as men even though on a violent purpose, while some suffered from this revolution. Also, there ere many more laws introduced to ensure womens rights. For instance, men werent allowed to have more than one wife. After Mayos control over China, the reform and opening up policy established by Eden Gapping has a lot effects on women empowerment too. In 1992, the percentage of women who have Jobs for over 15 years rose to 72. 33%. They took up half the labor force in rural areas. They could look for Jobs that dont require much skills. Women could now bring incomes to their families. However, the traditional idea of gender difference doesnt seemed to be moved from the Chinese completely. When the One Child Policy, which every family was only allowed to have one child, was introduced to control Chinas population, many baby girls are abandoned even now. This is because many Chinese still think that women are less valuable than men. Now, in modern China, women cant be more different than their ancestors. During the first half of the twentieth century, there werent much changes in the role of women. Rules established didnt get to the root of the problem. When it got to the late twentieth century, more effective changes ere made by both the government and the public. Women in modern China play an important role on Chinas work force. They now contribute a lot to every aspects of China. More than half of the worlds richest women are Chinese, including the top three. In my opinion, the role of women has faced a lot of regresses during each time periods but overall, they have gain many rights and respects by the governments. There are still bumps in the road as many traditional Chinese dont agree with women empowerment. I believe in the future, true gender equality in China will be

Thursday, November 21, 2019

Mass Customization Essay Example | Topics and Well Written Essays - 750 words

Mass Customization - Essay Example Nonetheless, it is fundamental to consider that the costs do not augment at all. The company is, therefore, able to have an added advantage in the market as well as have the best economic value in the market. A closer analysis of mass customization relates to the fact that the individual needs are actually met but with production in large quantities (Da Silveira, Borenstein & Fogliatto, 2001). This means that the manufacturers can to suspend production of goods for a particular customer and reschedule the same production for a larger supply. Production of large volumes as indicated in the work of Da Silveira, Borenstein & Fogliatto (2001) is a product of mass customization; thus, quality production and delivery. Minimal tradeoffs in costs are also an added advantage (Da Silveira, Borenstein & Fogliatto, 2001). In the business world, mass customization plays a huge role. As seen in the research conducted by Mattila, Huuskonen & Hietikko (2013) mass customization simply refers to the manufacturing guide for manufactures. This relates to the fact that the manufactures will produce goods based on the demands of the clients. As customizers, it is expected that the manufactures embrace a technique that will influence the shape of their final product to the desirability of the customers. Mass customization, therefore, is useful for the mass manufacturing of products with efficiency, production of goods for specific clients, and production of customized goods that are on demands after ordering of goods by clients (Mattila, Huuskonen & Hietikko, 2013). In the work of Mattila, Huuskonen & Hietikko (2013), mass customization is governed by various principles. First, mass customization works on the principle that a product should have independent sections that could be easily assembled into various forms of the product. This means that the manufacturers will incur less cost while producing the products. This is referred to as agile

Wednesday, November 20, 2019

Plato and the Platonic dialogues Essay Example | Topics and Well Written Essays - 1250 words

Plato and the Platonic dialogues - Essay Example In this effort Socrates bravely presents arguments relating to the need to life the examined life, as without living a life of purpose and meaning he believes there is no purpose in existence. Conversely, philosopher Robert Nozick in his book the Examined Life revisits this question of living a life of examination, yet considers it from a slightly different perspective than the one Plato advances through Socrates. This essay considers Plato’s characterization of the examined life through his dialogues Euthyphro and the Apology, examines Nozick’s conceptualization in the Examined Life, and contrasts the two philosophers views on the subject. One of the most seminal of Plato’s dialogues, the Apology constitutes Socrates’ argument to the Athenian court for his innocence. In considering this line of reasoning it’s important to consider the broader implications of Socrates argument. It seems that Socrates is indicating that in Meletus and the Athenian co unsel harming Socrates they are doing so in a sort of bad faith. Socrates believes that in being a better person than Meletus he has chosen to live his life virtuously. In living his life virtuously Socrates has contributed to society and lived his life in productive ways. He has also worked towards achieving his own sense of purpose and meaning; in Socrates’ instance, it seems that he believes this to be living honestly and spreading his wisdom and intellect to the Athenian youth. If Meletus were to have Socrates killed, which he is attempting.

Monday, November 18, 2019

What were the main economic and institutional differences between the Term Paper

What were the main economic and institutional differences between the studio system of the 1930s and 1940s and 'new Hollywood' post-1975 - Term Paper Example 20). A lot of talent was drained from western countries and the Hollywood nurtured that talent by providing them lucrative benefits and rich culture. The staring era of films in the Hollywood was the era of silent movies and the messages were delivered by the body language, sounds, and the sequence and some time running the text on the screen. However, the economic, technological and institutional transformation occurred around the world revolutionized cinematic activities and Hollywood witnessed major changes in the studio system during different eras. ... Some of the movies are inspired by the true events and some of them are inspired by the fabricated plots, fictions and the legends. Classical Era Types of the movies in the classical era (classical studio) As it seems clear by the name that the classical movies had class, these movies were based on the Fictional and real plots. Irrespective of the time frame, both the movies based on the idealism and realism has been presented and has become hit on the box office. The combination of the real situation has also been used in some movies like the De Vinci Code (2006) and it has been done irrespective of the time frame. Either the classical movies or the modern movies both have been reflecting the contemporary culture in their entities but the difference is the time, so understanding the difference of time can put a light on the above mentioned criteria of the question. The classical era had many glamorous stars which provided synergies to the film industry of that super glamorous era, a nd the faith killing beauties were cast with the support of solid stories. The beautiful faces were not the only criteria there, but the strong script was the trade mark of that era which is still believed as the golden era of the film industry Solid plots with strong theme and story Both Gone with the Wind (1939) and The Hunchback of Notre Dame (1939) were based on the bestselling novels and both movies were released in the same years. The 1930-40 was an era when the cream of best writer, directors and actors were coming there and it was a heaven for them (Chaplin, 2003, p. 91). A good work was immediately noticed in the Hollywood, and the feasibilities were made for them to release films on them. The industrialization affected the film industry and the base for

Saturday, November 16, 2019

Free Space Optical (FSO) Communication

Free Space Optical (FSO) Communication INTRODUCTION Free Space Optical (FSO) communication involves the transmission of data through a wireless medium using modulated near infrared light beam (with wavelength between 800 nm-1700 nm) [1] as carrier wave. FSO communication links can be used for satellite-to-satellite cross links [2] [3], up-and-down links between space platforms- aircraft, ships, and other ground platforms, and among mobile and stationary terminals within the atmosphere [3]. Light as a medium of communication is not a recent innovation as it was used in the Roman era, where polished metal plates where used as mirrors to reflect sunlight for long-range signaling. A similar sunlight-powered device was used by the U.S. military to send telegraph information between mountain tops in the early 1800s [4]. Additional optical communication developments occurred during the World War II, and the post-war era experienced further developments in this field fueled by electronic innovations such as the transistors, vacuum tubes and i ntegrated circuits, and most especially the invention of the laser in the early 1960s [1]. The unique characteristics of laser such as its powerful coherent light beam, the possibility of modulating it at high frequency and the low beam divergence has made it the preferred light source for enhanced FSO applications. FSO communication is considered to be one of the key technologies for realizing very-high-speed multi-gigabit-per-second large-capacity communications when fibre optic cable is neither practical nor feasible [4]. FSO communication can be of crucial advantage particularly because of its wireless nature and several applications, making it a viable alternative to the laying of fiber cable underground which is expensive and has environmental consequences. Unlike radio and microwave systems, FSO has higher data rate due to its high carrier frequency, low power requirements, no frequency license required and much smaller packaging [4]. In FSO links, atmospheric turbulence is capable of degrading the wave-front quality of a signal-carrying laser beam, resulting in signal loss at the receiver and thereby impairing the link performance [4],[5]. In addition, fog, snow, rain, dust, smoke and other aerosol particles contribute to the attenuation of the signal-carrying beam and eventual degradation of the FSO link. Several studies have been done on the atmospheric turbulence channels of a FSO system [3], [5]. The real performance measure of an FSO communication system is provided by the binary error probability also referred to as Bit Error Rate (BER).FSO communication involve the use of optical amplifiers either as an optical booster or optical preamplification. Amplification is achieved by stimulated emission of photons from dopant ions in the dopant fibre by using a pump laser as used in Erbium Doped Fibre Amplifiers (EDFA) or electrically as used in semiconductor lasers, due to the excitation of ions from a higher ene rgy state to a lower energy state. The excited ions can also decay spontaneously (spontaneous emission) or even through non-radioactive processes involving interactions with phonons of the glass matrix. These last two decay mechanisms compete with stimulated emission reducing the efficiency of light amplification introducing what is known as the Amplified Spontaneous Emission (ASE) noise. Digital Pulse Position Modulation (DPPM) with direct-detection is the preferred modulation technique for FSO communication systems because of the lack of dispersion over the free space channel [2] , none requirement of threshold for detection [3] and the complexity associated with phase or frequency modulation [5]. At the moment, the benefits of FSO communications have not been fully exploited, hence more applied researches are needed at the laboratory to help transfer the performance of FSO optical systems into real life applications. CHAPTER TWO LITERATURE REVIEW 2.1 FSO – PRINCIPLES AND CLASSIFICATION A FSO system consists basically of a transmitter, usually a modulated laser or light emitting diode (LED) which produces light for conveying data through space, and a receiver such as a photodetector which receives close to collimated radiation independent of the transmitter pointing concentrated lens [1]. Other components include beam control optics, collection lens, optical amplifier, solar radiation filters and other electronics [6]. In general, FSO systems can be classified into indoor and outdoor FSO communication [4], [7] based on the distance covered for communication and the absence of environmental effects in the indoor FSO link. The basic operating principles of indoor point to point systems are not different from outdoor communication links but the designs are very different to accommodate various requirements. Some research on transmitter and receiver designs for long-range FSO communication systems, [8] like satellite and atmospheric optical communications, have already been reported, which might be beneficial to short-range systems. Recently, many indoor communication systems employ laser diode as light sources [8]. 2.1.1 INDOOR FSO COMMUNICATION The indoor FSO communication link can be further classified as point and shoot links which are subdivided into infrared data association (IRDA) and retro-reflect links; and networks which have two types namely the diffuse networks and line of sight networks [4],[7]. Indoor FSO applications are confined to short distances; hence it is appropriate to optical FSO systems that use wide divergence beams rather than narrow beams which are suitable for point to point systems. Such systems are sometimes referred to as optical telepoint systems [7]. Due to the fact that indoor FSO systems are not affected by atmospheric effects, the power budget depends solely on the transmitter launch power, free space loss, and receiver sensitivity. As reported in Mahdiraji and Zahedi [9], the use of infrared frequencies for short-range wireless communications has received extensive interest over the decade, and many potential applications of this technology have been suggested. Some of the applications inc lude portable device such as laptop computers, personal digital assistants, and portable telephones. Many indoor communication systems employing infrared LED wireless links have been reported in [7], [9]. Using pure diffuse link, a high speed and power efficient indoor wireless infrared communication using code combining was reported in Majumdar and Ricklin [4], where a multiple transmitter link design was used with a narrow field of view direction diversity receiver. The design goal was to eliminate the effect of inter symbol interference (ISI) so that power efficient signalling schemes such as DPPM can be employed at a very high data rate. A portable transceiver for indoor FSO link was reported by Jiang et al [8] .The system employs a transmitter of eye safe infrared LEDs and a receiver of photodiode arrays with multi channel trans-impedance-summer architecture. The received signal achieved a BER of 10-4 at a plane of 2 m away from the transmitter, even at a point 50 degree off the transmitters vertical axis. The bit rate of the transceiver was up to 40 Mbit/sec in an indoor non-directed infrared FSO link to be extended to 100 Mbit/s using LEDs with higher cut frequency. 2.2.2 OUTDOOR FSO COMMUNICATION Unlike the indoor FSO communication link, the outdoor link covers a long distance over 500 m [7] using the atmosphere as its natural medium of communication. It is unlikely that long distance point-to-point systems will exceed the 4-5 km range due to atmospheric channel degradation. Outdoor point-to-point systems use high power lasers that operate in the Class 3B eye safety band to achieve optimum power link budget, particularly if high bit rate (e.g., 155 Mb/s) is required [7]. In order to achieve an improved power budget, an experiment was carried out by Heatley et al [8] to achieve a trial 155 Mb/s link that cover a 4 km distance between Imperial College and University College London. The aim of the experiment was to minimize the overall propagation loss focussing on the free space loss and the receiver sensitivity as little could be done to reduce the atmospheric losses. A low power laser coupled to an erbium doped fibre amplifier (EDFA) was used as the source; two astronomical t elescopes (Schmidt-Cassegrain, 20 cm aperture) were used at both the source and receiver ends, and an Avalanche photodiode (APD) was used as receiver. The result of the experiment was that the diameter at the receiver was reduced to 0.5 m which corresponds to 8 dB free space loss from a beam diameter of 2 m (20 dB free space loss). The major problem encountered was maintaining the beam alignment which depends on temperature changes. Although the APD receiver is relatively costly, it helped to improve the receiver sensitivity and they are generally used for long distance systems. FSO is well established for intersatellite and deep-space communications [3] but it can also be used in ground-to-space link, Unmanned-Aerial-Vehicle (UAV) to ground link, and among mobile and stationary terminals within the atmosphere [10]. New areas of application include quantum key, traffic and telematics [6]. It has been predicted that FSO can be fruitfully utilized as alternative for last-mile problem [3], [10], [11]. According to Majumdar and Ricklin [4], a group of researchers reported the design and development of acquisition, tracking and pointing subsystem for UAV to ground free space optical communications link. The communication link was developed from a UAV to stationary ground stations located at Wrightwood, California and Maui, Hawaii. The range of the UAV was 50 km. the downlink laser transmitter wavelength was 1550 nm and had power of 200 mW for developing a 2.5 Gbps data rate communication for a BER of 10-9. Furthermore researchers have presented results from exper imental demonstrations using a very lightweight optical wavelength communication without laser in space (LOWCAL) [4] between ground based telescope and a space shuttle. The uplink/downlink established at 852 nm wavelength and 852 nm signal beam. Some of the specifications for the experiment were: range of 640 km, data rate of 10 kbps, telescope diameter of 0.6 m, modular weight of 2-4 kg and retro-reflector area of 70-180 cm2. For the downlink, differential circular polarization keying (DCPK) format was used while Frequency Shift keying was used for the uplink. Both the downlink and uplink achieved a BER 2.2 FSO- TECHNOLOGICAL ADVANTAGES AND CHALLENGES Theoretically, the wavelength range of the near infrared electromagnetic spectrum (800 nm and 1700 nm [1]) used in optical communication implies it offers extremely high bandwidth, hereby providing higher data rates compared to other communication media such as the radio (1 mm-100 Mm ) and microwave (1 mm-1 m) systems [1]. Further, this technology requires no spectrum licensing requirements i.e. traffic free bands, no mutual interference between the FSO systems (high spatial selectivity of the beam), no Fresnel Zone requirement and difficult to eavesdrop on transmitted data [4], [6], [10]. The integration of the optical wireless and fibre is a research area been worked on by my many researchers [4]. This integration is possible because the two optical technologies offer high—speed optical bandwidth to meet market needs. They both use the same optical transmission wavelength (800 nm – 1700 nm) [1]. In addition the two optical technologies both share the same system compo nents and can transmit digital information using a range of protocols. The business advantages of FSO communications for network extensions include the reduction of cost incurred on fibre-optic cable and other associated costs, as well as time for deployments [4]. Despite its potentials, FSO communication link is affected by atmospheric attenuation owing to aerosol particles such as fog, haze, rain and snow which causes fluctuations in both the intensity and the phase of the received light signal hereby limiting the availability of FSO for a given transmission range and increasing the systems bit error rate [5]. These includes the fine mode with diameter, less than 2.5  µm, the accumulation mode with particle diameters 0.1  µm  µm and the coarse mode with diameter > 2.5  µm [12]. These particles can grow in size in regions of high humidity, and shrink by evaporation as humidity decreases. The effect of atmospheric aerosols in the channel on laser beam propagation can be determined using the Mie theory which depends critically on wavelength and particle size [13]. The dimensionless size parameter illustrates the nature of the Mie calculation as it gives the relationship between the particle size and radiation wavelength. This is given m athematically in equation 2.1[13] as where is wave number, is particle radius and is particle wavelength. Table 2.1 adapted from Ricklin et al [13] show some sources of aerosol in the atmosphere. Aerosol particles can be classified into three modes based on the diameter of the particles. Table 2.2 adapted from OBrien et al [6] shows the attenuations caused by rain, snow and fog. Table 2.1 Estimates of particles smaller than 20 micron radius emitted into or formed in the atmosphere (106 metric tons/year) (adapted from [13]) *Includes unknown amounts of indirect man-made contributions. Table 2.2 Attenuations caused by rain, snow and fog (adapted from [6]) Extinction is a term which describes the attenuation of a laser beam as it passes through a medium containing atoms, molecules, and particles. As reported in Ricklin et al [13], Goody and Yung defined the fundamental law of extinction as that of Lambert, which states that â€Å"the extinction is linear in both intensity of radiation and in the amount of matter, provided that the physical state (i.e., temperature, pressure, composition) is held constant†. Intensive researches [3], [4], [5], [13] have been conducted on the effects of atmospheric losses, most especially atmospheric scintillation, on FSO communication and some solutions have been proffered to reduce these effects. 2.2.1 PROPAGATION LOSS This atmospheric loss is associated with the distance covered by the laser beam. According to Prokes [12], free space propagation loss can be expressed as shown in equation 2.2 [dB] (2.2) where L is the link path distance, is the beam divergence full angle and is the diameter of transmitting circular aperture. For the Gaussian beam and a sufficiently long link distance ( >>) the additional gain is = 3.7 dB. In Heatley et al [7], it was reported that for a point-to-point system that operate with a slightly diverging beam, the free space propagation loss would be 20 dB whereas in an indoor system using wide angle beam, the free space loss would be 40 dB or more. At very short link distances, the total transmitted power is detected at the receiver because the beam spot diameter at the receiver position is lower than the diameter of the receiver lens [12]. 2.2.2 PHYSICAL OBSTACLES Physical obstructions such as birds, insects, tree limbs, buildings or other factors can temporarily or permanently block the laser line-of-sight [6], [13]. Platform/building motion due to wind, differential heating and cooling, or ground motion over time can result in serious misalignment of fixed-position laser communication systems [13]. Proper planning and site measurements are ways of avoiding this effect [6]. 2.2.3 ABSORPTION AND SCATTERING Molecular absorption process which is wavelength dependent is a major factor in beam attenuation. At wavelengths greater than 1 µm, the effect of molecular extinction can be negligible as atoms couple weakly with electromagnetic field [4]. Furthermore, molecular absorptions at these wavelengths are due to absorption of incident radiation with only minor scattering contributions [4]. Aerosol scattering effect is caused by rain, fog, mist and snow. This effect accounts for the degradation in quality of service experienced during snow, rain, fog and mist as reported in a detailed measurement take by [7] over a period of one year in both rural and urban areas. The results also reported in Heatley et al [7], showed a similar trend but with rather less variability between seasons and higher average attenuations. For many molecules, the absorption spectra have been measured experimentally in the laboratory and the respective extinction ratios of specific molecules have been made available for evaluation [4]. Molecular absorption can be minimized by appropriate selection of the optical wavelength [4]. It has also been suggested in [7] that the attenuation effects due to scattering can be minimized by reducing the link range and/or reducing the optical power budget. The attenuation caused by scattering in decibel scale A10, scat is given by the product of the atmospheric attenuation coefficient ÃŽ ±10, scat and the link distance in kilometres. The mathematical expressions are shown in equations (2.3), (2.4) and (2.5) [12]. [dB/km] (2.3) Where is the particle size distribution coefficient defined as: [dB] (2.5) 2.2.4 ATMOSPHERIC SCINTILLATION Scintillation is caused by solar energy heating up small air pockets inhomogenously, thereby creating varying refractive index along the FSO link [7]. This results in the scattering of laser beams at various angles along the propagation path and a resultant fluctuation in both the intensity and phase of the received light [5], [7].Atmospheric scintillation is less significant at distances less than 500 m [7], [12], but degrades performance of a FSO link at ranges of the order of 1km or longer [5]. The intensity I of an optical wave propagating through turbulent atmosphere is a random variable. The normalized variance of optical wave intensity, referred to as the scintillation index, is defined by equation (2.6) [12] where the angular brackets denote an ensemble average. The scintillation index indicates the strength of intensity fluctuations. For weak fluctuations, it is proportional and, for strong fluctuations, it is inversely proportional to the Rytov variance for a plane which is shown in equation (2.7) [12] where is the refractive-index structure parameter. This parameter is dependent on temperature, humidity, atmospheric pressure, altitude and wind strength [12]. Beam wander is another occurrence in an atmospheric channel which causes similar effects as atmospheric scintillation. This is characterized by the deflection of the entire laser beam by optical tubules of larger diameter than the beam, resulting in a random movement of the light beam about the target point. Atmospheric scintillation is a major impairment of FSO communications systems, as it can produce large transient dips in the optical signal. It has been studied extensively with various theoretical models already proposed to describe the signal fading [3], [5], [11]. In addition, several communication techniques have been described to mitigate the signal fading effect [5], [6], [12], [13]. In [3], the error performance of terrestrial FSO links were modelled as PPM/Poisson channels in turbulent atmosphere. The scintillation effects were modelled as lognormal for weak turbulence and as exponential for heavy turbulence. In Kiasaleh [11], the performance of a direct-detection, APD-based PPM FSO communication system in atmospheric turbulence was characterized. Here the weak turbulence link was investigated by modelling the received signal as a log-normal random process and also as a negative exponentially distributed received signal intensity. The binary PPM was used as the modulation sch eme for the system. It was assumed that the receiver thermal noise is non-negligible and the average signal intensity was large enough to justify as Gaussian approximation. It was concluded that the performance of the APD-based PPM FSO system was severely affected by turbulence and that the optimum APD gain must be used to avoid excessive APD noise at the receiver. It was also concluded that the negative exponential channel scintillation affected the systems performance with only large signal power capable of influencing the performance. Zhu and Kahn [5] employed the statistical properties of signal fading, as a function of both temporal and spatial coordinates as an approach of mitigating turbulence-induced intensity fluctuation. In spatial domain technique, at least two receivers are used to collect the signal light at different angles. In temporal domain techniques, only one receiver is used. Here signal-by-signal maximum likelihood detector (ML) is used to optimize performance w hen the receiver knows only the marginal statistics of the fading while maximum-likelihood sequence detection (MLSD) is used when the receiver knows the temporal correlation of the fading. The investigation showed that BER has greater degradation when the standard deviation of the turbulence induced fading is large. Furthermore, the diversity reception with the two receivers can improve the performance than a single receiver. According to Prokes [12], the receiver lens area causes an integration of various intensities incident on particular parts of the lens. It was reported in [12] that optical scintillations can be reduced by increasing the collection area of the receiver lens. This phenomenon is known as aperture averaging and the aperture averaging factor for a spherical wave is shown in equation (2.8) [12] where is the power scintillation index and is the Rytov variance for the spherical wave. An experiment was carried out by Prokes [12] to investigate the effect of the aperture averaging factor on the power scintillation index using two different refractive index structure parameters for the calculation. The result showed that the influence of both the lens diameter and refractive-index structure parameter on the scintillation level was relatively large. The power link budget of a FSO communication link was given in [12] based on statistical analysis of the atmospheric attenuation. Figure 2.1 shows a power level diagram of FSO deployed at a distance of about 1 km. According to figure 1, the total received optical power, was given by Prokes [12] in equation (2.9) as where is the mean optical power of a laser diode, includes the coupling loss between the laser and the transmitter lens and the attenuation loss in the lens, is the beam attenuation due to propagation loss, includes random losses caused by atmospheric phenomena (scattering and turbulence), and represents the coupling lens between the receiver lens and photodiode and the attenuation and reflection at the lens. 2.2.5 AMPLIFIED SPONTANEOUS EMISSION (ASE) Optical amplifiers are important components in communication links, as they are used to boost output power levels in the order of one Watt and higher. Due to the atmosphere medium used in FSO, only optical booster and pre-amplification schemes can be used [14]. Apart from the desired optical signal amplification, the optical booster amplifier constitutes a source of background radiation that can exceed the background radiation from the sun. This radiation is called amplified spontaneous emission (ASE). The ASE power spectral density is represented in equation (2.10) [14] as where is one photon energy, denotes the optical amplifier gain, and is the amplifiers noise figure which ideally should be 3 dB. Equation (2.10) is valid for a single spatial mode (including polarization modes); in multimode applications has to be multiplied by the number of emitted modes to arrive at the total ASE power spectral density [14]. The effect of ASE radiation in optical booster and preamplification in FSO communication link was investigated by [14] using on/off keying (OOK) as the modulation technique. In the case of the booster amplifier, considering the fact that the maximum on-axis gain of a central unobscured optical transmit antenna with respect to an isolator radiator equals where is the diameter of the telescope optics and is the optical transmit wavelength .The value 0.81 is the optimum value of the fraction of incident power that can be coupled to an optical fibre from an incident plane wave. On inserting into equation (2.10), the ASE power spectral density generated by the booster amplifier and coupled to the receiver is given in equation (2.11) [14] as [W/Hz] (2.11) where is the transmitter gain, is the transmitter noise figure and and are the transmitter and receiver telescope diameter respectively. Also the signal power coupled to the receiver was given in equation (2.12) [14] as [W] (2.12) where is the transmit optical power at the output of the booster amplifier. Figure 2.2 [14] shows the general setup of an optically boosted FSO system. Modulated TX data Optical Receiver Optical booster amplifier GTX, FTX Telescope optics DTX Amplified data signal transmit booster ASE DRX R Using Erbium-doped booster amplifiers with specifications, telescope diameters, and a communication distance of , Winzer et al [14] arrived at which is of the order of the magnitude of the background radiation per mode produced by the sun. It also was reported that the booster ASE constitutes the dominating background radiation term up to communication distances of 600 000 km. In the optically preamplified FSO communication system, (see Figure 2.3) the received signal passes through polarization filter and optical bandpass which reduces the detected preamplifier ASE power. The preamplification introduces additional noise terms such as the shot noise, ASE-shot beat noise, signal-background beat noise, signal-ASE beat noise, background-preamplifier ASE beat noise, background-background beat noise and the ASE-ASE beat noise. It was reported by Winzer et al [14] that up to a link distance of 1000 km the beating of the signal and the transmit booster ASE dominates all other noise terms, c ausing the signal-to-noise ratio (SNR) to become independent of R. The communication quality does not in this case increase with decreasing communication distance. It was thus concluded that the optical booster ASE has significant impact on the performance of a FSO communication link, especially at short link distances [14]. Optical preamplifier POL- filter (optional) Optical bandpass Decision logic RX data In Winzer et al [14], the use of the pointing, acquisition and tracking (PAT) system (see figure 2.4) to reduce the optical booster ASE at the receiver was presented. The proposed patent-pending PAT system eliminates the need for the using separate power or hardware for beacon lasers, taking care of alignment procedures between the beacon-laser and the transmit or receive telescopes, and splitting off a certain fraction of the information carrying data signal for PAT purposes [14].The booster ASE is applicable to the PAT system because the ASE spectrum exceeds that of the data signal by orders of magnitude and also the ASE has the same spatial modes as the data signal. Figure 2.4 The PAT system retrieving pointing/tracking information from ASE emitted by the booster amplifier at the transmitter [14] Phillips et al[2] carried out an analysis of the optically preamplified intersatellite pulse position modulation (PPM) receiver employing maximum likelihood detection (MLD) using Gaussian approximation (GA) and Chernoff bound (CB) techniques. The results from the calculations carried out at a wavelength of and bit rate of 25 Mb/s showed that this mentioned receiver configuration is approximately 1.5 dB more sensitive than the optically preamplified OOK non-return-to zero (NRZ) signalling. This method is proposed to have future implementation in future laser intersatellite communication systems. This paper has been reviewed in my report, with special interest in the BER evaluation. 2.2.6 EYE SAFETY FSO systems involve the emission of high power optical power which can be unsafe, especially if operated incorrectly [7]. As a result of this, laser safety standards have been established and classified based on the amount of power emitted by the transmitter source. Table 2.3 (adapted from [7]) summarizes the principal classifications. Table 2.3 Laser safety classifications for point-to-source emitter (adapted from [7]) 650 nm (visible) 880 nm (infrared) 1310 nm (infrared) 1550 nm (infrared)

Wednesday, November 13, 2019

Nursing Ethics: Patient Abandonment Essay -- Nursing Case Study

This case study examines a case of an LPN who became ill while about halfway through her shift and chose to go home. This LPN was assigned to care for five patients in an obstetrical ward, four of which were considered stable. The fifth patient was awaiting an obstetrical consultation when the LPN became ill and vomited. At this time, she notified the other nurses and, subsequently, the charge nurse that she needed to leave due to illness. The charge nurse instructed her to notify her supervisor prior to leaving the facility; however, the LPN chose not to do so and went home. Her reasoning in not notifying her supervisor as she was instructed was that she feared that the supervisor would ask her to go to the emergency room for care. The LPN testified that she did not want to pay for an emergency visit and that she intended to make an appointment with her family doctor early that same day. The facility terminated the LPN’s contract and also reported her to the state boa rd of nursing for patient abandonment. As a judgment, the board of nursing suspended here nursing license pending a psychological examination and fined her $1000 for abandoning her patients. In this paper, we will examine the viewpoints of the LPN, the charge nurse, and the nursing supervisor as they relate to the Nurse Practice Act and the board of nursing. While the art of nursing has been around for centuries, the United States enacted the first nursing laws in 1903. The first nursing acts where developed as a response to conflict between nursing roles and physician roles. Nursing Practice Acts are enacted by each state’s legislature. Texas enacted the Nurse Practice Act in 1909. These acts are broad in regards to the practice of nursing, so the reg... ...ent’s needs and rights ahead of her own and ultimately do the right thing by her clients. Works Cited McDonald, Mackay & Weitz, llp,(2009). The texas board of nursing. Retrieved from http://www.healthlicensedefense.com/nurseshtml The Texas Board of Nursing,(2009). Nursing practice act. Nursing peer review, nurse licensure compact, & advanced practice registered nurse compact. Austin, TX Texas Board of Nursing, . (2004, February 1). Rules and regulations. Retrieved from http://www.bne.state.tx.us/nursinglaw/rr.html Wilson, N.R. (2011). Legal issues and the school nurse. Retrieved from http://staffweb.esc12.net/~mbooth/school_nurses/New_Nurse_Orientation_Manual/Willson_Nancy_Roper_%20Legal%20Issues%20and%20the%20School_Nurse_7-14-091.pdf Wright, L.D. (2011, February 8). Nursing jurisprudence. Retrieved from http://www.nursing-jurisprudence.com/