Application Of EM Waves In Satellite Communication Computer Science Essay

Application Of EM Waves In Satellite Communication Computer Science Essay This paper deals with the historical development of satellite communication systems. Then the basic elements of satellite communication system along with their features are discussed. Then the working of a satellite communication system and the use of EM waves in this system is discussed and then finally the applications, advantages and limitations of satellite communication system are discussed. Introduction Electromagnetic wave is a wave of electric and magnetic field components which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation. Generally, EM radiation (the designation radiation excludes static electric and magnetic and near fields) is classified by wavelength into radio, microwave, infrared, the visible region we perceive as light, ultraviolet, X-rays and gamma rays..The behaviour of EM radiation depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. Spectroscopy can detect a much wider region of the EM spectrum than the visible range of 400  nm to 700  nm. Electromagnetic waves as a general phenomenon were predicted by the classical laws of electricity and magnetism, known as Maxwells equations. If you inspect Maxwells equations without sources (charges or currents) then you will find that, along with the possibility of nothing happening, the theory will also admit nontrivial solutions of changing electric and magnetic fields. Any electric charge which accelerates, or any changing magnetic field, produces electromagnetic radiation. Electromagnetic information about the charge travels at the speed of light. Accurate treatment thus incorporates a concept known as retarded time. At most wavelengths, however, the information carried by electromagnetic radiation is not directly detected by human senses. Natural sources produce EM radiation across the spectrum, and our technology can also manipulate a broad range of wavelengths. Fig. 1 electromagnetic spectrum Satellite Communication A satellite is a physical object that orbits or revolves around some celestial body. In general satellite is an artificial satellite stationed in space for the purposes of communication, military, surveillance, etc. A satellite communications (sometimes abbreviated to Comsat) is an artificial satellite stationed in space for the purposes of telecommunications using microwave frequencies. Most communications satellites use geosynchronous orbits or near geostationary orbits, although some recent systems use low Earth-orbiting satellites. Communications satellites provide a technology that is complementary to that of fibre optic submarine communication cables. Unlike fibre optic communication, satellite communication has a propagation delay (also called a path delay) of at least 270 milliseconds, which is the time it takes the radio signal to travel 35,800 km from earth to a satellite and then back to earth. Satellite Internet connections average a 600-800 millisecond delay, about ten times than that of a terrestrial Internet link. This delay is a challenge to deployment of Virtual private networks over satellite internet connections. HISTORY OF SATELLITE COMMUNICATION The concept of satellite communications was first proposed by Arthur C. Clarke, based on Herman PotoÄ niks pseudonymous work from 1929. In 1945 Clarke published an article titled Extra-terrestrial Relays in the magazine Wireless World. The article described the fundamentals behind the deployment artificial satellites in geostationary orbits for the purpose of relaying radio signal. Thus Arthur C. Clarke is often quoted as the inventor of the communications satellite. The first artificial satellite was the SOVIET SPUTNLK-1 launched on October 4, 1957, and aquipped with an onboard transmitter that worked on two frequencies i.e. 20.005 and 40.002 MHz The first American satellite to relay communications was project SCORE in 1958 which used tape recorder to store and forward voice messages. Telstar was the first active, direct relay communications satellite belonging to AT T. USE OF EM WAVES IN SATELLITE COMMUNICATION The fastest growing and most recent field of communication involves the use of various satellite relays. Let us discuss the space wave communication. In this mode of propagation, electromagnetic waves from the transmitting antenna reach the receiving antenna either directly or after reflections from ground in the earths troposphere region. Troposphere is that portion of the earth which extends up to 16 km from the earth surface. It means in the former, wave reaches directly from the transmitting antenna to receiving antenna and in later, the wave reaches the receiving antenna after reflection from the ground., where the phase change of 180 degree is also introduced due to reflection at the ground, in the ground reflected wave. Although both the waves leave the transmitting antenna at the same time with the same phase but may reach the receiving antenna either in the phase or out of the phase, because the two wave travel different path lengths. The strength of the resultant waves, thu s, at the receiving point may be stronger or weaker than the direct path alone depending upon whether the two waves are adding or opposing in phase. At receiving point the signal strength is the vector addition of direct and indirect waves. Space wave propagation is also called as tropospheric propagation because space wave propagates through troposphere. Space wave propagation is mainly in VHF, and higher frequencies because at such frequencies sky wave and ground wave propagation both fail. Beyond 30 MHz sky wave fails as the wavelength becomes too shorts to be reflected from ionosphere and ground waves are propagating close to the antenna only, as attenuation is very high. Therefore just after few hundred feet ground wave also die due to attenuation and wave tilt. Space wave propagation is also called as the line of sight propagation because at VHF, UHF and microwave frequencies, this mode of propagation is limited to the line of sight distance and is also limited by the curvatur e of earth. Although in actual particle space wave propagates even slightly beyond the line of sight distance due to the refraction in the atmosphere of the earth. In line of sight distance transmitting antenna and receiving antenna can usually see each other. In fact, the line of sight distance i.e. range of communication can also be increased by increasing the heights of transmitting and receiving antennas. The curvature of earth and the height of the transmitting and receiving antennas determines maximum range of communication through direct waves. In fact, the line of sight distance has now been extended by what is known as Space Communication or specially Satellite communication which has facilitated trans-oceanic propagation of microwaves with the potentiality of large bandwidth. By space communication we mean the radio traffic between a ground station and satellite or space probe, between satellites or space probes and also between the ground station itself via man made communication satellites or natural space body( e.g. the sun, the moon, the venus etc. ). Earlier it was not possible to propagate beyond the radio horizon and hence it revolutionized the field of communication engineering and it is possible to show that three geosynchronous satellites can establish communication over entire world. Role of electromagnetic waves can be seen by studying the different bands available for satellite communication Selection of the band The selection of the band is not something that individual service providers decide, but is rather chosen by large satellite operators based on different factors. These are explained below: C-band is still the most widely available worldwide. Ku-band is becoming more available recently in regions which were less covered in the past (South America, Asia, Africa). C-band is more prone to interference from other transmission services that share the same frequencies (adjacent satellites or terrestrial transmissions) than the higher bands. While the C-band technology is cheaper in itself, it requires larger dishes (1 to 3 m) than Ku- and Ka-band (0.6 to 1.8 m) and therefore imposes relatively higher (installation) costs on the end-user. Ku- and especially Ka-band make better use of satellite capacity. Higher frequency bands (Ku- and especially Ka-) suffer significantly more from signal deterioration caused by rainfall: to ensure availability in bad weather conditions, the signal has to be much stronger. Note that 0.1% of unavailability means in fact that the service will be interrupted for almost 9 hours over a 1-year period. 1% unavailability represents 90 hours or almost 4 full days. Bands of Interest C-band is the oldest allocation and operates in the frequency range around 6 GHz for transmission (uplink) and between 3.7 and 4.2 GHz for reception (downlink). Ku-band is the most common transmission format in Europe for satellite TV and uses around 14 GHz for uplink and between 10.9 and 12.75 GHz for downlink. Ka-band uses around 30 GHz up- and between 18 and 20 GHz downlink frequency. C-band and Ku-band are becoming congested by an increasing amount of users, so satellite service operators are more and more turning to the use of Ka-band. Using C-band and K-band C Band is a name given to certain portions of the electromagnetic spectrum, as well as a range of wavelengths of light, used for communications. The IEEE C band and its variations, in particular, are microwave ranges used for certain satellite television broadcasts, and by some Wi-Fi devices, cordless phones, and weather radars. Typical antenna sizes on C-band capable systems ranges from 7.5 to 12 feet (2.5 to 3.5 meters) on consumer satellite dishes, although larger ones also can be used. Slight variations of C band frequencies are approved for use in various parts of the world. TABLE I C Band Variants Around The World Band Transmit Frequency (GHz) Receive Frequency (GHz) Extended C Band 5.850-6.425 3.625-4.200 Super Extended C Band 5.850-6.725 3.400-4.200 INSAT C Band 6.725-7.025 4.500-4.800 Palapa C Band 6.425-6.725 6.425-6.725 Russian C Band 5.975-6.475 3.650-4.150 LMI C Band 5.725-6.025 3.700-4.000 K band is defined as a frequency band between 20 and 40 GHz (7.5-15 mm). The IEEE K band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging between 18 and 27 GHz. K band between 18 and 26.5 GHz is absorbed easily by water vapour (water resonance peak at 22.24 GHz, 1.35 cm). The IEEE K band is conventionally divided into three sub-bands:  · Ka band: K-above band, 26.5-40 GHz, mainly used for radar and experimental communications.  · K-band 18-27 GHz  · Ku band: K-under band, 12-18 GHz, mainly used for satellite communications, terrestrial microwave communications, and radar, especially police traffic-speed detectors. MAIN COMPONENTS OF A SATELLITE COMMUNICATION SYSTEM Satellite communications are comprised of two basic elements The satellite The ground station The Satellite The satellite is also known as the space segment. It is composed of the following separate units; the satellite and telemetry controls and the transponder. The transponder comprised of the receiving antenna to catch-up signals from the ground station, a broad band receiver, an input multiplexer and a frequency converter that is used to reroute the received signals through a high powered amplifier for downlink. The main function of satellite is to reflect signals. In case of a telecom satellite, the primary role is to pick up signals from a ground station, which is located, a considerable away from the first. This relay action can be two way, as in the case of a long distance phone call. Another use of satellite is the television broadcasts. Number of programs are first up-linked and then down-linked over wide region. The customer having appropriate devices can receive and watch the programs. One of the modern uses of satellite is getting information along with image (commonly known as space/satellite image) of any desired location on earth. Fig. 2 diagram showing satellite and ground station The Ground Station This is called the earth segment. Earth station is the common name for every installation located on the Earths surface and intended for communication (transmission and/or reception) with one or more satellites. A base band processor, an up-converter, high Powered amplifier and a parabolic dish antenna is involved to transmit the terrestrial data to an orbiting satellite. In the case of downlink, the ultimate reverse operation is being down and up-linked signals are recaptured through parabolic antenna. WORKING OF A SATELLITE Satellite is mainly working on the basis of Electromagnetic waves. In our daily life EM waves are useful for Radio, Internet, T.V etc. For all these electronic equipments are working on the basis of EM waves. Firstly a satellite is keep in the orbit. Then it rotates along the orbit. From the source station it receives signals and spread them to all the electronic equipments. Satellites easily transfer news with in fraction of seconds it means in microseconds. In order send signals the smallest frequency waves are required. At the station the producers send the microwaves to satellite, because microwaves are waves having short frequency when compare to the other waves (Microwaves are electromagnetic waves with frequency from 30MHz to 1GB) ,they can easily penetrate throw the ionosphere, and reaches to satellite. Satellites provide links in two ways. Firstly a satellite provide point to point communication link between one ground station and the other. One ground station transmit signal to the other satellite and next ground station receives them from the satellite. Secondly, satellite receives signals from one ground station and transmits to them to the number of ground receivers. It is illustrated in figure 2. Most satellite use frequency bandwidth through from 5.92 to 6.4GHz from transmission of data from earth to the satellite and a frequency bandwidth from 3.7 to 4.1GHz for transmission from satellite to the earth. A satellite can provide service to a certain part of the earth if it is in sight. This can be done only if the satellite remains stationary with respect to the earth. LOW EARTH ORBITING COMMUNICATION SATELLITE In 1960, the simplest communications satellite ever conceived was launched. It was called Echo, because it consisted only of a large (100 feet in diameter) aluminized plastic balloon. Radio and TV signals transmitted to the satellite would be reflected back to earth and could be received by any station within view of the satellite. Fig. 3 diagram showing Echo satellite Unfortunately, in its low earth orbit, the Echo satellite circled the earth every ninety minutes. This meant that although virtually everybody on earth would eventually see it, no one person, ever saw it for more than 10 minutes or so out of every 90 minute orbit. Telstar satellite Telstar is the name of various communications satellites; including the first ever such satellite able to relay television signals. The first two Telstar satellites were Telstar 1, launched July 10, 1962 and operational until February 21, 1963, and Telstar 2, launched May 7, 1963 and operational until May 16, 1965. They were experimental, and nearly identical. Telstar 1 relayed the first television pictures, telephone calls and fax images through space and provided the first live transatlantic television feed. Telstars orbit was such that it could see Europe and the US simultaneously during one part of its orbit. During another part of its orbit it could see both Japan and the U.S. As a result, it provided real- time communications between the United States and those two areas for a few minutes out of every hour. Some of the main advantages of low and medium earth orbit include: (a) the possibility of using hand-held receiver terminals because satellites are closer to the Earth and can therefore provide stronger signals at the receiver and ground stations need to transmit at lower power; (b) the possibility of reusing the frequencies more often than is possible with geostationary orbit because the geographical area covered by low earth orbit satellites is much smaller; (c) the possibility of reduction in transmission delay. Fig. 4 diagram showing Telstar satellite Geostationary Communications Satellites In 1963, the necessary rocket booster power was available for the first time and the first geostationary satellite, Syncom 2, was launched by NASA. For those who could see it, the satellite was available 100% of the time, 24 hours a day. The satellite could view approximately 42% of the earth. For those outside of that viewing area, of course, the satellite was NEVER available. Fig. 5 diagram showing Geostationary satellite INDIAS FIRST COMMUNICATION SATELLITE APPLE Apple stands for Airline Passenger Payload Experiment. It got the name as it was carried as a Passenger by the European space agency. Apple the first Indian three-axis stabilized geo-stationary experimental communication satellite, weighing 673kg was successfully launched on June 19, 1981 from Kourou, French Guyana, by the Ariane Launch Vehicle of European Space Agency on its third developmental flight. After 17 minutes 25 seconds the craft was successfully placed in the transfer orbit. The space craft sub-systems were functioning normally. Test commands have been issued from SHAR to the APPLE space craft successfully. Fig. 6 diagram showing APPLE satellite Launch Date: 19.06.1981 Launch Vehicle: Ariane-1(V-3) Type of Satellite: Geo-Stationary Satellite Mission: Experimental geostationary communication Weight: 670 kg Communication: VHF and C-band Stabilization: Three axis stabilized (biased momentum) with Momentum Wheels, Torques Hydrazine based Reaction control system Mission life: Two years APPLICATIONS OF SATELLITE COMMUNICATION The breakthrough provided by satellites in telecommunications resulted in a major research and development effort in all the related technologies. Most of the early work concentrated on international point to point telecommunications applications. Later, the application of satellite communication was extended to the direct satellite broadcasts (1970s), mobile communications (1980s), and personal communications (1990s). In general, satellites are serving the mobile and broadcast. Radio and Television Broadcasting Satellites have been used since 1960 to transmit broadcast television signals between the network hubs of television companies and their network members. Sometime, a whole set of programs is transmitted at once and recorded at the affiliate, and then broadcast to the local populace according to the appropriate time. In the 1970s it became possible for private individuals to download the same signals that the network and cable companies were transmitting, using C-band reception dishes. This free viewing of the corporate contents by individuals let to scrambling and subsequent resale of the descrambling codes to individual customers, which started the direct-to-home industry. The direct-to-home industry has gathered even greater response since the introduction of digital direct broadcast service. . Business Radio And TV Digital television has made it possible to distribute information within organizations and companies that are geographically dispersed, or to deliver distance education. Similarly, digital radio allows for the delivery of radio services to relatively small closed user groups. Thin Route or Trunk Telephony Telecom operators have been using satellite communications for many years to carry long-distance telephone communications, especially intercontinental, to complement or to bypass submarine cables. To the end-user this is transparent: the phone calls are routed automatically via the available capacity at any given moment. Mobile satellite telephony Mobile telephony allows the user to make telephone calls and to transmit and receive data from wherever he/she is located. Digital cellular mobile telephony such as GSM has become a worldwide standard for mobile communications, but its services lack coverage over areas that are sparsely populated or uninhabited (mountains, jungle, sea), because it is not economically viable or practical for the network operators to build antennas there. Satellite telephony seems to be able to provide a possible solution to the problem of providing voice and data communications services to these other locations Marine Communications In the marine community, satellite communication systems such as Immarsat provide good communication links to ships at sea. These links use a VSAT type device to connect to geosynchronous satellites, which in turn links the ship to a land based point having respective telecommunications system. Global Positioning Services Another VSAT oriented service, in which a small apparatus containing the ability to determine navigational coordinates by calculating a triangulating or the signals from multiple geosynchronous. Military Satellite System For military communications Army, Air force and Navy use both fixed and mobile satellite systems. In addition to the normal communications, military communications are also required for tactical communications from remote and inhospitable locations. The special requirements of military communication terminals are high reliability, ruggedness, compact, operations under hostile environment, immunity to jamming, ease of portability and transportation, etc. Examples of military satellite communications systems are: DSCS (US AF) SKYNET (UK) NATO (NATO) FLTSATCOM (US NAVY) MILSTAR Because of the special frequency band used in Military satellite system and other special requirements, Military satellite Systems are always much costlier and it takes longer time to design and develop compared to commercial satellite communications systems. Realizing that not all communications are strategic in nature, there is a trend now to use commercial communications system as far as possible. US Department of Defence is one of the major users of commercial Iridium satellite system with their own gateway. Broadband Satellite System Broadband satellite service is an emerging service which has caught the fancy of many for meeting the demand of worldwide fibre like access to telecommunications services such as computer networking, broadband Internet access, interactive multimedia and high quality voice. These systems use advanced satellite technology at Ka band or Ku band frequencies to achieve the high bandwidth requirements. Examples of proposed Broadband Satellite systems are: Teledesic, SkyBridge, Spaceway LIMITATIONS OF SATELLITE COMMUNICATION Latency (Propagation Delay) Due to the high altitudes of satellite orbits, the time required for a transmission to navigate a satellite link (2/10ths of a second from earth station to earth station) could cause a variety of problems on a high speed terrestrial network that is waiting for the packets. Poor Bandwidth Due to radio spectrum limitations, there is a fixed amount of bandwidth allocable to satellite transmission. Noise The strength of a radio signals strength is in proportion to the square of the distance travelled. Due to the distance between ground station and satellite, the signal ultimately gets very weak. This problem can be solved by modulation of carrier wave. Conclusion The outer space has always fascinated people on the earth and communication through space evolved as an offshoot of ideas for space travel. The earliest idea of using artificial satellites for communications is found in a science fiction Brick Moon by Edward Evert Hale, published in 1869-70. While the early fictional accounts of satellite and space communications bear little resemblance to the technology as it exists today, they are of significance since they represent the origins of the idea from which the technology eventually evolved. The satellite communication through the EM waves has many applications for the smooth functioning of life and it made the communication with each other very simple. In the area of satellite communications, the technology has been responsive to the imaginative dreams. Hence it is also expected that technological innovations will lead the evolution of satellite communications towards the visions of today. Acknowledgment I would like to express my gratitude to all those who gave me the possibility to complete this term paper. I want to thank department of Electronics and communication of lovely professional university for giving me permission to commence this term paper. I have further more to thank the EMFT faculty member, Mr. Princejeet Singh. I am bound to the physics faculty for their stimulating support. My friends Amit and Sulabh supported me in this term paper. I want to thank them for their help, support, interest and valuable hints. Especially I would like to thank my sister who helped me and enabled me to complete this term paper.

Nursing Ethics Essay

What is personal ethics? Many people have their own perceptions and definition of what personal ethics are. When speaking about personal ethics this topic deals with what an individual believes to be morally right or wrong. Personal ethics comes from what one was taught by child by their caregiver whether it was mom, dad, grandmother, grandfather, aunt, or uncle. Since these ethics were instilled in us as children by our caregivers we carried these ethics into our daily lives and the decisions that we made. As a child my mother main focus was to make sure I knew right from wrong. As a parent she just didn’t say that something was wrong, but she told me why it was wrong. I think this is the most important aspect when understanding ethics and why people make the decisions they make. I think it is important to hold personal ethical views so when one is being faced with a challenging moral issue they will be able to efficiently handle the situation. My mother and grandmother based their ethical views according to their religious background. Both my mother and grandmother are Christian ministers and their views were guided from the Bible. As a nurse I make ethical decisions every day. Some of these ethical decisions are easy and some not quite so easy; however, my decision is based upon how I was taught and my personal beliefs and what is the best outcome for the patient. I think as a nurse I am still learning and can always make room for improvement. My personal ethics are constantly being tested as a nurse and the decision I make not only influences patients but also my peers. As a nursing manager in my facility it is my job that I make good ethical decisions because I have other nurses looking at me to make concrete decisions in some cases. Values are a person’s principles or standards of behaviors. My value is what I consider to be important in life. What is important to me may not be important to someone else. This is what I had to consider in the world of nursing. I  would come to accept that everyone is different and though they are different and values are different we both should be able to respect one’s views and decisions. This is important so that we may achieve our primary goal of purpose which is to care for the patient. My values and beliefs are rooted and grounded in my Christian background. Values that I was taught as a child was â€Å"do unto other as you would have them do unto you†. Simply put to treat people how you want to be treated. This causes a sort of immediate feedback for creating our moral standards and making ethical decisions (Scivicque, 2007). As a manager, I have learned how to be humble, and listening and learning from others. Another important value that was instilled in me as a child was to share and to be grateful for what you have. This I come to realize that I being a young woman most women my age have not accomplished the things that I have. By knowing this I do not take my career for granted. I enjoy my co-workers and patients that I work with. I enjoy overall caring for people and watching them thrive towards their highest potential. An example of an ethical dilemma I might encounter in the nursing field is the giving of blood to a Jehovah Witness. According to a Jehovah Witness’ beliefs they do not believe in administering blood or blood products for life-saving measures. The ethical dilemma is what do you do in an emergency situation? What if their beliefs go against everything you stand for? M best response in this situation is to focus on the patient as a whole. As a nurse we have to care for the patient physically, spiritually, mentally, and socially. Physically the patient would need a blood transfusion, but spiritually the patient will decline due to beliefs. I think this is the perfect opportunity to educate the patient of the risk and benefits of receiving the blood transfusion. As a nurse I take my job very seriously. While I’m working I ask myself what if these patients were my family members. How can I be present with the patient and listen to their concerns without judging them as a person? These are all questions I have to ask myself when providing care to my patients. I am not a perfect nurse by far but I am striving to be the best versatile nurse I can be to ensure that my patients reach their optimal level of wellness. References Scivicque, C. (2007). Developing Personal Ethics. Retrieved from http://suite101.com/article/developing-personal-ethics-a34018

The Purposes of the Three Witches in Macbeth

The Purposes of the Three Witches in Macbeth Macbeth is a symbolic story of how people can be easily influenced. In the beginning of the play, Macbeth meets the three witches and hears about his prophecy from them which he will become the next King of Scotland. These witches are important characters to develop the story. Every time when Macbeth needed them, he received prophecies from them. These prophecies affect Macbeth and reveal his evil personality. As revealed in the play, the purposes of the three witches in the play are to foreshadow, advance the plot, and show the human weakness.One of the purposes of the witches in the play is to set allusions. In the beginning of act one scene one, the three witches plan? to meet at the open field to see Macbeth after the battle is over. As they promised, they wait for Macbeth and Banquo to return from the battlefield. When they faced each other, the third witch said, â€Å"All hail, Macbeth, that shalt be king hereafter†(Macbeth 1. 3. 51) to Macbeth. Then the first witch tells Banquo that, â€Å"Thou shalt get kings, though thou be none/ So all hail, Macbeth and Banquo! †(Macbeth 1. 3. 8-69), which she meant that Banquo will become the father of the kings. Later in the story, Macbeth seeks for the three witches to hear more about his future. They told him that â€Å"Be bloody, bold, and resolute. Laugh to scorn/ The power of man, for none of woman born/ Shall harm Macbeth. †(Macbeth 4. 1 81-83). These prophecies eventually become true. There are no doubts that the tree witches allure the story by telling the futures. The weird witches not only foreshadow but also advance the story. The story mainly develops by the prophecies.After Macbeth hears about his future from the witches, he writes a letter to Lady Macbeth, his wife, about the prophecy. Since Lady Macbeth had no doubt about this prophecy of Macbeth becoming the king, she plans to assassinate the King Duncan to fulfill the prophecy. Macbet h and Lady Macbeth put their plan into action. Successfully, Macbeth killed the king and put false charge on Malcolm and Donalbain for assassinating the king to become sovereign. As a result, Macbeth took the next throne of the Scotland.While he rules Scotland with insanity, Malcolm seeks for revenge and makes an army to fight against Macbeth. With a growing fear in Macbeth’s heart, he goes to find the three witches again to receive another prophecy. He gets told that no men who came through a woman’s womb could harm him. He scoffs and eases his fear of death. However towards the end of the play, he faces death by Macduff, who was delivered by cesarean section. By giving prophecies, the witches indirectly affect the play to create tensions.The play of Macbeth clearly showed the human weakness. The witches did not force Macbeth to kill the king or to commit any crimes. Macbeth was a loyal general of King Duncan along with Banquo. However, after he hears the words from t he three weird sisters, he had a conversation with Banquo about what they heard and he says, â€Å"My thought, whose murder yet is but fantastical,/ Shakes so my single state of man/ That function is smothered in surmise,/ And nothing is but what is not† (Macbeth 1. . 142- 145). From this conversation, his personality was revealed which he is a man who would not kill the king to attain his ambition. However, Macbeth eventually gets affected by the prophecy that he shows his ambitions toward the kingship and his evil personality. His influenced aspect is clearly shown when the second witch notes, that â€Å"By the pricking of my thumbs,/ something wicked this way comes† (Macbeth 4. 1. 44-45). From this quote, it shows that Macbeth’s personality became evil.The purposes of the witches are not only to develop the story but also to show that people are easily influenced. The weird sisters, the three witches, in the play do not advent often but have essential roles. They give prophecy to Macbeth which creates ambition in his heart. They are the main element that creates the consequences in the play. Their role in the story gave Macbeth a thought that they know he would expand on and reveal his human weakness. Work Cited Shakespeare, William. Macbeth. New York: Signet Classic, 1987. Print

The Geriatric Population Is Surging Across The World

The geriatric population is surging across the world, â€Å"Triumphant advances in medicine combined with economic and social development are resulting in increased longevity in the world’s population† (Hanson, 2014, p. 225). Aging is an undeniable process, and though there are techniques and procedures that may minimize the appearance of aging, the biological process itself, is unpreventable. However, it is ironic that the Western world correlates and glorifies youth and beauty whilst it simultaneously holds prejudiced views against the aging process, even though every individual ages with every second that passes. Stereotypes are exaggerated, prejudiced, and distorted generalizations that degrade individual uniqueness by creation of†¦show more content†¦The cost of living especially in Canada is a steady increase and as a result, job security is of paramount importance for everybody in the general public. Without a stable and proper income, an individual†™s existence is difficult to maintain. Additional stressors such as an increase in age and stereotypical views embedded into society are elements that must be overcome. This is the situation older adults are facing in the Canadian society nowadays. By definition, â€Å"ageism refers to prejudice against older people† (Novak, Campbell Northcott, 2014, p. 7). Ageism is relevant to the discussion of why it is more difficult for the senior population to access jobs to maintain living expenses. Stereotypical beliefs such as â€Å"older adults are commonly considered to be less productive and less trainable and promotable than younger workers,† (Malinen Johnston, 2013, p. 446) can increase discrimination leading to barriers in job access. This results in a forced and early retirement, which can be causative factors of lowered standards of living for the elderly (Noelke Beckfield, 2014). Age discrimination can also impede on opportunities for employment due to stereotypes employers might have during job application evaluations and interviews (Irving, 2015). Despite evidence that there are â€Å"no performance differences between older and younger employees, or that older workers even outperform younger employees, discrimination against older workers can be evident†