Digital graphics Assignment Example | Topics and Well Written Essays - 500 words

Digital graphics - Assignment Example Additionally, there have been developments in printers since they were first created, where they were very slow and basic printers. They used to be expensive at the time unlike now, where one can purchase them easily. The only problem is that such printers take a long time to print and therefore, shows how much printers have upgraded but expensive. To add to this there are new printers that have come up and made currently, as well as increases speed of printing as well as lowers costs (Niemeyer, 2008, 23-144). Development of mobile phones also has a big effect on the design and creation of images. Latest mobile phones’ models have cameras, which can be used to take photos and transfer them to a computer using either Bluetooth technology or a data cable. In addition, some mobile phones have such as latest smart phones have inbuilt softwares that can be used to edit images. E-book readers have also had a great impact on the design and creation of images. E-books are now designed in such a way that they are compatible with both the computers and

Natural Law Essay Example | Topics and Well Written Essays - 1250 words

Natural Law - Essay Example They are based on social advantage and the practical effects they make on the society and the community. The author claims that the beliefs and wishes that are held by the human kind or more specifically a human has some transcendental basis and by this a hint in the religious side of matter relies. The foundational sense of it all is arbitrary and that men cannot help themselves in feeling or understanding it. The necessity to survive is a great struggle and condition which involves eating and drinking. Without survival basis nothing makes sense in the world of humans and the habitat that they possess 1. As this suggests that laws are present for the benefit of the community and not a single individual but if categorized, they are then aimed for the benefit of the man, which is a part of the larger community. By â€Å"transcendental basis†, Holmes means that the religious values or other inner morals that the individual holds. In no way are the laws that are made constant but they rather keep changing with the society as per need. In reference to Homes view on the natural law and his take on the general idea, it seems that most of it is influenced by Social Darwinism and the social pragmatic values of the society which are more influenced by the society we live in. He asserts that laws are made and adapted according to the environment of man and are not dictated from generations to generations and this is a slow but gradual process of betterment. Holmes position in the paper is made clear that he believes in the changes of the environment as a trigger to implement or change the existing laws that are held by the mankind. The morality of every law and moral consciousness depends on the ideology held by the society or the individuals that shape up the society. Holmes justifies his position on a clear stance of moral consciousness and the

Block Diagram Of A Communication System Computer Science Essay

Block Diagram Of A Communication System Computer Science Essay The doorway to the nowadays wireless communication systems was opened by Guglielmo Marconi when he transmitted the three-dot Morse code for alphabet S by the use of electromagnetic waves over a 3-KM link in 1895. This laid the foundation of modern communication systems ranging from broadcasting, satellite transmission and radio eventually progressing to nowadays cell phones. It wouldnt be wrong to say that wireless communication has indeed revolutionized our present society A sudden increase has been observed in the expansion of radio systems during the last two decades. We have seen great evolution in Wireless communication systems from 1G narrowband analog systems in the 1980s to the 2G narrowband digital systems in the 1990s. Now the existing 3G wideband multimedia systems are being deployed. In the meantime, research and progress in the future-generation wideband multimedia radio systems is vigorously being pursued worldwide. To connect mobile users to the public switched network the United States introduced first radiotelephone service by the end of the 1940s. Improved Mobile Telephone Service was launched by Bell Systems in 1960s due to which lots of improvements like direct dialing and increase in bandwidth took place. IMTS formed the bases of the first analog cellular systems. The term cellular was used due to the fact that coverage areas were split cells, they had a low power transmitter and receiver. BLOCK DIAGRAM OF A COMMUNICATION SYSTEM Figure 1. Block diagram of a general communication system. ANALOG vs. DIGITAL COMMUNICATION SYSTEMS Definition of Digital A method of storing, processing and transmitting information through the use of distinct electronic or optical pulses that represent the binary digits 0 and 1. Advantages of Digital low-priced reliable Easy to manipulate Flexible Compatible with other digital systems The information in digital form can only be transmitted without any degradation through a noisy channel Incorporated networks Disadvantages of Digital Sampling Error As compared to analogue, larger bandwidth is required in digital communications for the transmission of the same information. Synchronization in the communications system is required to recognize the digital signals, but this is not the case with analogue systems. Definition of Analogue Analogue is a transmission standard that uses electrical impulses to emulate the audio waveform of sound. When you use a phone, the variations in your voice are transformed by a microphone into similar variations in an electrical signal and carried down the line to the exchange. Advantages of Analogue less bandwidth is required More Accurate Disadvantages of Analogue Signal loss and distortion can be seen due to the effects of random noise which is impossible to recover GENERATIONS OF CELLULAR SYSTEMS The concept of cellular telephony was introduced in AMPS, short for Advanced Mobile Phone Systems. AMPS divided the total area into small regions called cells and this was from where the concept of cellular telephony started. Cellular Systems had many advantages such as they increased quality, capacity, reliability and availability of mobile telephone network. The generations of cellular systems are described below. FIRST GENERATION CELLULAR SYSTEMS First generation cellular telephone systems were introduced in 1980s. They were based on Analog Frequency Modulation technique. Each channel was assigned a sole frequency. First generation cellular systems offered only wireless voice services based on analog technology. Digital signals were only used for control information such as dialing a number etc. These systems were no able to cope with the increasing demands of users also they had very less capacity and provided poor voice quality. Some first generations systems are Advanced Mobile Telephone System, AMPS NAMPS, AMPS Total Access Cellular System (TACS) Nordic Mobile Telephone System (NMT-900) SECOND GENERATION CELLULAR SYSTEMS Second Generation Cellular Systems provided larger capacity and provided much better services to users compared to first generation systems. They were based upon Digital Modulation technique which led to great enhancement in networks capacity. Second Generation Systems used multiple access techniques such as TDMA and FDMA. The biggest draw back of Second Generation Systems was that its different systems were not compatible with each other. Therefore roaming between different systems was not possible. Some of Second Generation Systems are North American Digital Cellular, NADC Global System for Mobile Communication, GSM Pacific Digital Cellular, PDC CDMAONE, IS-95 CDMA In order to overcome Second Generation compatibility problem with increased data rates of modern internet applications, 2.5 Generation standards were developed. The best thing about them was that they allowed already existing Second Generation systems to be upgraded so that they can be used for higher data rate transmission. 2.5 Generation brought a new revolution in cellular telephony by supporting services like high speed internet and location based mobile services. Some of 2.5 Generation Mobile Systems are General Packet Radio Service, GPRS Enhanced Data Rate for GSM Evolution, EDGE THIRD GENERTAION CELLULAR SYSTEMS Designed to provide high quality and high capacity in data communication, Third Generation Systems require sophisticated spreading and modulation techniques. Third Generation Systems are aimed to provide voice quality comparable to land line telephony and also to support high data rate. These systems are compatible with circuit switched as well as packet switched data services. They are also compatible with the existing networks and use radio spectrum much more efficiently than before. Some Third Generation Systems are Wideband CDMA, WCDMA Universal Mobile Telephone System, UMTS CDMA 2000 BEYOND 3G The highly developed version of the 3G mobile communication are the 4G mobile communication services. It is estimated that 4G mobile communication services will give increase in capacity, data transmission with high speed, broadband, HQ color video images for users, graphic animation games in 3D, audio services in 5.1 channels. For the system and architecture of 4G mobile communication many researches are done. Developments are made in the terminal protocol technology for high speed packet services, larger capacity, enabling downloading application programs by public software platform technology, multimode radio access platform technology, and high quality media coding technology over mobile networks. Why 4G? Services like wireless internet and teleconferencing can be carried by 4G. Global mobility and service portability. Wider bandwidths. Increased bit rates. Less expensive. Mobile networks can easily be scaled. CHAPTER # 02 Multiplexing is a process in which a single carrier is used to transmit several different signals. These several signals are transmitted all together by combining them and forming one signal that will effectively move through the carrier bandwidth. When one transmission is done and the signal reaches the destination point, the integrated signal re-assembles into its actual form and is then received. Multiplexing is one of the most used techniques today in almost every communication system. Because of the technological advance multiplexing, we have seen major increase in efficiency of a wide range of telephony services and online applications. Multiplexing has become an effective technique that assists in everything from video conferences and web conferences up to bulk data transmissions and even making a simple Point-to-Point phone call. FDMA: FDMA is the most usual technique used for multiple accessing. FDMA stands for frequency division multiple access. It is clear from its name that in this technique the frequency is divided among the users as the available spectrum is shared among them in the frequency domain. The message signals are transmitted onto carriers for different users using particular RF frequencies. Within FDMA structural design the Single Channel Per Carrier (SPSC) is the simplest method where each channel is provided with a separate carrier. This scheme finds its essence in the fact that the channels are assigned on the basis of demand. Within a cell all the channels are available to all users all the time, and the channels are assigned as soons as a message signal is received or a request is made. Guard bands are used to reduce the chances of interference from adjacent channels. These guard bands are present between the bands allocated for various channels. In the implementation of the first analog cellular systems, FDMA is the multiplexing technique that was used. TDMA: Time division multiple access techniques allots different time intervals to different users for the transmission of signals and storage of the data is carried out in one frequency channel not like FDMA which uses one frequency per channel. Users are allowed to use the same frequency but the time slots are divided. In TDMA techniques the available spectrum is divided into small frequency bands as in FDMA, which are further sub-divided into various time slots. The user can access the frequency channel only for time slot allotted to him. User can use periodically the particular duration of time. In TDMA systems, guard bands are required between both frequency channels and time slots. SDMA: SDMA stands for Space-Division Multiple Access. It is a MIMO (Multiple-Input, Multiple-Output, a multiple antenna schematic architecture) based wireless communication network architecture. It enables access to a communication channel by the process of identifying the user location and establishing a one-on-one mapping between the network bandwidth allotment and the acknowledged spatial location that is why its mostly suitable for mobile ad-hoc networks. For majority of the well known mobile communication architectures such as CDMA, TDMA and FDMA, SDMA architecture can be configured and implemented CDMA: CDMA stands for Code division multiple access. CDMA systems are based on the spread spectrum technique. In which transmissions by all the users are carried out simultaneously while operating at the same frequency and using the entire spectrum bandwidth. For the identification and extraction of required transmission, each user is allotted with a unique code which cannot match with any other user. This issue of identification is due to the fact that all the users transmit simultaneously. To ensure this privacy, pseudo-random noise codes or PN codes are used. These codes are actually the orthogonal codes and its advantage is that it reduces the chances of cross correlation among themselves. By using this PN code assigned to the specific user, modulation of the message signal from an individual user is done. Then we have the CDMA frequency channel through which all the modulated signals from different users are transmitted. At the receivers end, the desired signal is then recovered by de-spreading the signal with a replica of the PN code for the specific user. The signals whose PN codes are not matched with the desired signal and are assigned to different users are not de-spread and as a result are regarded as noise by the receiver. CDMA differs from both TDMA and FDMA in a way that it allows users to transmit the signal at the same time and operate at the same nominal frequency so it requires less synchronization whereas in TDMA and FDMA frequency and time management is very critical so more dynamic synchronization is required. One more advantage of CDMA is that complete systems spectrum is used by signals and hence no guard bands are required to protect against adjacent channel interference. Intro to Spread Spectrum Communications Following are the major elements that can clearly describe the Spread Spectrum communications: By spread spectrum, bandwidth far in excess is available than that is necessary to send the information. Due to this characteristic the transmission can be protected against interference and jamming at the same time providing multiple access capability. An independent code known as the Pseudo random code is used for signal spreading across the bandwidth. The distinct nature of this code separates spread spectrum communications from typical modulation techniques in which modulation always spreads the spectrum somewhat. For the recovery of the original signal the receiver is synchronized to the deterministic pseudo random code. Users can transmit the signal at the same time and operate at the same nominal frequency by using independent code and synchronous reception. In order to protect the signal from interference a pseudo-random code is used. It appears to be random to anyone who does not have its pre-defined knowledge but in reality is deterministic, it is because of this fact that receiver is able to reconstruct the code needed for the recovery of the required data signal. This code used for synchronous detection is also called Pseudo noise sequence. Types of Spread Spectrum Communications Spreading of bandwidth of the signal can be achieved by three ways: Frequency hopping The signal is shuffled between different centre frequencies within the entire bandwidth available to the hopper pseudo-randomly, and the receiver used already knows where to look for the signal at a given time. Time hopping The signal is transmitted in short bursts pseudo-randomly, and the receiver knows when a burst is expected. Direct sequence Very high frequency is used to code the digital data. The code is pseudo-randomly generated. The same code is generated at the receiver end, and in order to extract the original data this code is multiplied to the received information stream. CHAPTER # 03 SOURCE CODING AND DIGITAL MODULATION 3.0 INTRODUCTION Digital Modulation is performed in order to represent digital data in a format that is compatible with our communication channel. Why Digital Modulation? Digital modulation schemes have greater capacity to convey large amounts of information than analog modulation schemes. 3.1 DIGITAL DATA, DIGIITAL SIGNAL Digital signal is binary data encoded into signal elements. Different encoding schemes for encoding digital data into digital signal are: 3.1.1 Non Return to Zero (NRZ) In NRZ there are two different voltage levels for 0 and 1. There is no transition in the middle of the bit. The absence of signal denotes 0 and a positive voltage level denotes 1. Figure 3.1, Non Return to Zero (NRZ) The major drawback of NRZ scheme is that it adds a dc component to the signal. 3.1.2 Multilevel Binary (AMI) In this encoding scheme there are more than two levels. No signal represents 0 and 1 is represented by some positive and negative voltage level. 1s pulses are opposite in polarity. Figure 3.2, Multilevel Binary (AMI) There is no dc component in this scheme and also there is no loss of synchronization for consecutive 1s. 3.1.3 Manchester Coding There is transition in middle of each bit, which acts as a clock as well as data. The low to high transition represents 1 and high to low represents 0. Figure 3.3, Manchester Coding 3.1.4 Differential Manchester In this scheme transition at the middle of the bit represents only clocking while transition at start represents 0 and no transition at start represents 1. Figure 3.4, Differential Manchester 3.2 ANALOG DATA, DIGITAL SIGNAL Analog data is first converted into digital data by using analog to digital converters. These converters use different techniques to complete their task, some of them are: 3.2.1 Pulse Code Modulation If a signal is sampled at regular intervals at a rate higher than twice the highest signal frequency, the samples contain all the information of the original signal. Each sample is assigned a digital value. Although its quality is comparable to that of analog transmission but still in this process some information is lost and the original signal can never be recovered. Figure 3.5, Pulse Code Modulation Delta Modulation Analog input is approximated by a staircase function. Function moves up or down at each sample interval by one level (d). Figure 3.6, Delta Modulation Delta modulation is easier than PCM in implementation, but it exhibits worse signal to noise ratio for the same data rate. But it is good for data compression. DIGITAL DATA, ANALOG SIGNAL Different digital modulation techniques are: Amplitude Shift Keying (ASK) A modulation technique in which digital data is represented as variations in the amplitude of a carrier wave is called Amplitude-shift keying (ASK). One binary digit is represented by presence of carrier, at constant amplitude and the other binary digit represented by absence of carrier. Figure 3.7, Amplitude Shift Keying (ASK) 3.3.2 Frequency Shift Keying (FSK) In frequency shift keying different frequencies are used to represent incoming digital data. Say in case of Binary Frequency Shift Keying f1 is used to represent 0 while f2 is used to represent 1. Figure 3.8, Frequency Shift Keying (FSK) In MFSK more than two frequencies are used and hence bandwidth is more efficiently utilized. 3.3.3 Phase Shift Keying (PSK) A digital modulation technique in which data is transmitted by modulating and changing the phase of the reference signal is called Phase-shift keying (PSK). In case of PSK, a finite number of phases are used. A unique pattern of binary bits is assigned to each of these phases. Generally, each phase encodes an equal number of bits. The symbol is formed by each pattern of bits that is represented by the particular phase. Figure 3.9, Phase Shift Keying (PSK) Figure 3.10, Constellation Diagram of BPSK The bandwidth of ASK and PSK are specified as: Whereas the bandwidth of FSK is given as: Where, R is the bit rate DF = f2 fc = fc f1 CHAPTER # 04 CHANNEL CODING 4.0 INTRODUCTION Why Channel Coding? In modern digital communication systems information is represented in bit streams, which are then modulated to analog waveforms before being transmitted onto a channel. At receiver this analog information is demodulated into bit streams, but because of the presence of interference and noise in the communication channel this bit stream may be corrupted. So to minimize occurrence of bits in error and protect digital data from channel noise and interference channel coding is used. How Channel Coding is performed? Additional redundant bits are added to the message data stream to perform channel coding, these extra bits assist in error detection and correction at the receivers end. Channel Coding at the cost of? Channel Coding is performed at the cost of bandwidth expansion and data rate reduction. 4.1 TYPES OF CHANNEL CODING TECHNIQUES There are two main types of channel coding techniques, Block Codes Convolutional Codes. Block Codes accepts k number of information bits and generate a block of n number of encoded bits, and thus are commonly known as (n.k) block codes. Some common examples of block codes are Hamming Codes and Reed Solomon Codes. Convolutional Coding is forward error correction technique that is currently most widely used in modern communication systems, this particular technique is used for real-time error correction. Unlike block codes which append redundant bits at the end of original message signal, Convolutional coding form a new codeword using original data stream. The encoded bits are not solely dependent on k current input bits but at the same time on precedent input bits. 4.2 CONVOLUTIONAL CODES In this project Convolutional Coding is implemented. Convolutional Codes are further classified as 1. Trellis Coded Modulation (TCM) 2.Turbo Codes. Trellis Coded Modulation (TCM) is non recursive, non systematic and does not require an interleaver. Turbo Codes on the other hand are recursive, systematic, parallel structured and they also require interleaver. In Wideband CDMA systems TCM is used for all channels while Turbo Codes may be used for DCH and FACH channels. Turbo Codes are sometimes classified as separate branch of Channel Codes so from here onwards word Convolutional Code will only be used for TCM. Types of Transmission Channels Coding Schemes Coding Rate RACH Convolutional Coding 1/2 BCH PCH DCH, FACH 1/2, 1/3 Turbo Coding 1/3 Table 4.1, WCDMA Specifications 4.3 CONVOLUTIONAL CODE REPRESENTATIONS 4.3.1 Polynomial Representation No. of input information bits = k No. of encoded bits = n No. of stages (Constraint Length) = K Code Rate = k/n Encoded CodeWord = U The following example shows how Convolutional Codes are represented. Let g1(x) and g2(x) be encoder polynomials, where g1(x) = 1 + x + x2 g2(x) = 1 + x2 Let input message bit stream be 101, therefore input message bit stream polynomial will be, m(x) = 1 + x2 The encoded codeword U will be combination of product of g1(x) with m(x) and g2(x) with m(x), m(x) x g1(x) = 1 + 1.x + 0.x2 + 1.x3 + 1.x4 m(x) x g2(x) = 1 + 0.x + 0.x2 + 0.x3 + 1.x4 Therefore the codeword U, becomes U = (1,1) + (1,0).x + (0,0).x2 + (1,0).x3 + (1,1).x4 U = 1 1 1 0 0 0 1 0 1 1 4.3.2 State Transition Diagram Convolutional Coding can be represented using State Transition Diagram. Following are State Transition Diagram and State Transition Table for code rate 1/2. Figure 4.1, State Transition Diagram for Code Rate  ½ Table 4.2, State Transition Table for Code Rate  ½ Again for the same input bit stream 10100, the codeword U = 11 10 00 10 11. In the input message last two 00 bits are tail bits. 4.3.2 Block Diagram Representation The following diagram shows block diagram representation of Convolutional Coding with Code Rate = 1/2 Constraint Length (No. of Stages) = 3 Figure 4.2, Block Diagram Representation of Convolutional Code with Code Rate =  ½ The following example illustrates the process of Convolutional Coding using block diagram representation for input bit stream 101. So the final codeword becomes, U = 11 10 00 10 11 4.3.2 Trellis Diagram Representation For input bit stream 101, the following diagram shows how Convolutional Coding is performed using Trellis Diagram Figure 4.3, Trellis Diagram Representation CHAPTER # 05 PULSE SHAPING TECHNIQUES 3.0 INTRODUCTION Why Pulse Shaping? It is done in order to reduce Inter Symbol Interference commonly known as ISI. How Pulse Shaping is performed? In order to achieve zero-ISI the overall system response must be equal to Nyquist frequency response. 5.1 RAISED COSINE FILTER Inter Symbol Interference significantly degrades the data detector ability to differentiate between a current symbol from diffused energy of adjacent symbol. This leads to the detection of error and increases BER. So in order to cater ISI, a real-time realization of Nyquist filter is applied in modern communication systems. Raised cosine filter is one of the realization of Nyquist filter. where r = roll-off factor = 1 ≠¤ r ≠¤ 0 and T = symbol period = 1/R Roll-off factor determines the filter bandwidth and represents a trade-off between the sharpness of the transition band of the filter and impulse response ringing magnitude of the filter. A Nyquist filter has following properties: Time response eventually goes to zero in a time period exactly equal to the symbol spacing. By sampling the symbol sequence at a given symbol time point, present symbol is not affected by the energy spreading from the adjacent symbols. The impulse response and the frequency response of the RC filter is Figure 5.1, Impulse Response of RC Filter Figure 5.2, Frequency Response of RC Filter Time response of the RC filter goes to zero with a period that exactly equal to the symbol spacing. As the response equals zero at all symbol times except for the desired one none of the adjacent symbols interfere with each other. 5.2 ROOT RAISED COSINE FILTER RC filter is divided into a root raised cosine (RRC) filter pair, with one at the transmitter end, which performs the pulse shaping in order to constrain the modulated signal bandwidth, and the other at the receiver end, that performs matched detection for optimizing the SNR of a known signal in AWGN presence. The Root Raised Cosine filter is so named because its transfer function exactly is the square root of the transfer function of the Raised Cosine filter. Where r = roll off factor and T is symbol period. The RRC filter bandwidth is equal to the root mean square (RMS) amplitude 2R. The impulse response and the frequency response of the RRC filter is Figure 5.3, Impulse Response of RRC Filter Figure 5.4, Frequency Response of RRC Filter Both RC and RRC have similar pulse shapes, but the RRC pulse makes slightly faster transitions, therefore the spectrum of RRC pulse decays more rapidly as compared to the RC pulse. Another important difference between both pulses is that the RRC pulse does not have zero Inter Symbol Interference. Because of the fact that RRC filter is used at transmitter and receiver both, the product of these transfer functions is a raised cosine, which will result in zero ISI output. 5.3 ROLL OFF FACTOR The roll-off factor, r, is a measure of the excess bandwidth of the filter, i.e. the bandwidth occupied beyond the Nyquist bandwidth of 1/2T. Where à ¢Ã‹â€ Ã¢â‚¬  f is excess bandwidth and Rs is symbol rate. CHAPTER # 06 SPREAD SPECTRUM Spread spectrum is a type of modulation where the data is spread across the entire frequency spectrum. This process of spreading the data across the entire spectrum helps signal against noise and interference. These techniques are mostly employed in cell phones and also with wireless LANs. To qualify as a spread spectrum signal, two criterions must be met The transmitted signal bandwidth must be in excess of the information bandwidth. Some function other than the data being transmitted is used to establish the bandwidth of the resultant transmission. Why Spread Spectrum ? Due to its exclusive and peculiar properties spread spectrum is preferred over other modulation schemes. Some of these properties are characterized as advantages and disadvantages of a basic spread spectrum system below. Advantages †¢ It reduces the effects of multipath interference and at times removes them entirely. †¢ Frequency band is shared simultaneously with other users. †¢ Pseudo random codes ensure protection of transmission and privacy. †¢ As the signal is spread over an entire spectrum it has a low power spectral density. Disadvantages †¢ Due to spreading operation it consumes more bandwidth. †¢ It is at times difficult to implement. Types of Spread Spectrum Techniques Most commonly used techniques in a spread spectrum systems are Direct Sequence Spread Spectrum Frequency Hopping Spread Spectrum Frequency Hopping Spread Spectrum A frequency hopping spread spectrum hops from one narrow band to another all within a wider band. In general the frequency hopper transmitter sends data packets at one carrier frequency and then jumps to another carrier frequency before sending ore packets and continues the same routine throughout the period of transmission. The pattern that emerges seems to be random but is in fact periodic and easily traceable by pre configured transmitter and receiver. These systems can be vulnerable to noise at a particular hop but usually are able to send packets during the next hop. Direct Sequence Spread Spectrum Most widely used technique of spread spectrum is the Direct Sequence Spread Spectrum. A Direct Sequence Transmitter receives the incoming data stream which is to be transmitted and then converts it into a symbol stream where the size of a symbol can be one or more bits. Using any of the modulation schemes for digital systems such as Quadrature Amplitude Modulation (QAM) or Quadrature Phase Shift Keying (QPSK) this symbol stream is multiplied to a noise like sequence known as pseudo random sequence. It is also know as a chip sequence. As a result of this multiplication the bandwidth of the transmission is significantly increased. Figure 3. Direct Sequence Spread Spectrum System Figure 3. shows the working of a basic Direct Sequence Spread Spectrum system. For clarity purposes, one channel is shown working in one direction only. Transmission For each channel a distinct and different Pseudo random code is generated. In order to spread the data the data stream is multiplied with the previously generated Pseudo random code. The signal obtained as a result of this multiplication is then modulated onto a carrier. This modulated carrier waveform is then amplified before broadcasting. Reception The carrier wave is amplified as soon as it is received by the receiver. The signal received is then multiplied with a locally generated carrier which gives the spreaded signal. Again a Pseudo random code is generated on the basis of the signal expected. The process of correlation is carried out on the received signal and the generated code which gives the original message signal. Pseudo-Random Noise The spread spectrum systems are constructed very similar to other conventional systems. The difference being the addition of pseudo random generators both at the transmitter and the receiver which generate the Pseudo noise sequences required for the functionality of Direct Sequence spread spectrum. These pseudo random noise sequences are used for spreading the signal at the transmitter side and dispreading at the receiv

Hypnotherapy Essay -- Health, Smoking Cessation

Hypnotherapy is widely recognised, as a method for aiding smoking cessation, however, conflicting evidence exists regarding its efficacy. In meta analysis hypnosis proved 3 times more effective than nicotine replacement methods, and 15 times more effective than stopping without help (Schmidt and Chockalingham, 1992). Having said this, results are not always clean cut. A number of studies report a mixture of success rates i.e. 90.6% (Barber, 2001), 90% (Klager, 2004), and 80% (Crasilneck, 1990), while others report much lower rates of success at 48% (Elkins and Rajab, 2004) and 25% (Ahijevych, Yerardi and Nedilsky, 2000). Something else to consider is the variety of methods that may be adopted in order to treat smoking cessation with hypnosis, as the efficacy of these methods may also vary (Crasilneck, 1990; Barber, 2001; Spiegel, Frischholz, Fleiss and Spiegel, 1993). However, the constant variable within smoking cessation treatment is the patient. Therefore, treatment tailored towar ds the individual needs of the smoker needs to be considered when evaluating the best approach to therapy. This is a non-clinical case study exploring whether multi session tailored treatment may better serve the individual needs of certain smokers. Therefore, hypnotherapeutic techniques are tailored to the patient’s needs in order to achieve optimum success. The patient (D) is a male actor. He lives with his partner who has recently stopped smoking with hypnosis. He is 31 yrs old and has been smoking for 18yrs. This is D’s third attempt at smoking cessation. Initially D attempted to stop smoking without help and was unsuccessful. D’s second attempt involved single session smoking cessation, and failed to achieve lasting results. Therefore a multi ses... ...to practice relaxation techniques autonomously over a three-day period before his second session of hypnosis. D had showed Case Study, London. prolonged abstinence in the past and is living with a significant other (who has now stopped smoking); therefore, it would seem probable that low level of hypnotisability may have been elemental in impeding his progress, initially. Research suggests that high hypnotisability facilitates successful behaviour modification (Frischolz et al, 1993). Therefore, in D’s case, this needed to be addressed before further therapy could commence. However, it has been suggested that abstinence from smoking does not correlate with hypnotisability (Holroyd, 1991). Nevertheless, it could be argued that within this study, low rate of abstinence i.e. 16% may have impeded verification of a relationship between hypnotisability and outcome.

Motivation in different cultures Essay

There has been general upsurge in cultures and managerial research in the last decade or so. Despite this fact, empirical studies on culture dimensions to management practices across cultures have been limited in numbers and scope. In few countries, very limited knowledge about its cultural values and the consequences it poses for motivation is known. A major question is whether the drawback of universal theories could explain for the disappointing economic development of various countries. A few reports suggest that there is difference in application of motivational theories in different parts of the world. In view of these differences, untrimmed Western management models may not be very appropriate for adoption all over the world, in general without recourse to the prevailing local cultural values. The suggestion is made to look for appropriate and suitable management models for different cultures by studying the relatively more successful local companies and institutions. Key words: Motivation, Management, Cultures, Values INTRODUCTION: Motivation has kept people in crises going throughout centuries; it has been the cause of increased standards of living, success, fortune, and satisfaction. Most leaders throughout history have used varying techniques of motivation and persuasion. The same is true for successful managers. According to many, the role of motivation in the work environment has great value. Many studies have evolved around various motivational techniques for directing employees towards desired goals. However, â€Å"the challenge to management is to recognize and understand the impact of various motivational systems on individual and group behavior within an organised work endeavor. The success or failure of motivation rests not only on the technique but also on management’s ability to match the needs of people with appropriate rewards† –Todes, 1977. Motives are needs, which force people to move towards goals, or point they define. Studies of motivation have tried to respond to the ‘why’ of the human behavior, which is directed towards a goal and the need for that goal. Hersey and Blanchard (1977) noted that motives can be defined as needs, wants, drives, or impulses within the individual which are directed towards goals which may be conscious or subconscious. Freud long ago discovered the importance of subconscious motivation; in order words, people are not always aware of everything they want (Hersey and Blanchard, 1977). Dickson (1973) stated that employees are not motivated solely by money but by other factors, which is linked to their behaviour and attitudes. Many theories of motivation have been developed with the understanding of how employees’ behaviours can be energized positively and how they can better be directed to achieve desired objectives. The relevance of cultures to management with the sole purpose of contributing to a culturally feasible motivation theory building across cultures is to be known. Motivation practice in different societies requires identification of the ‘growth-positive’ and ‘growth-negative’ culture based-factors. Defining motivation: According to Stephen (2000), motivation is the willingness to exert a persistent and high level of effort towards organizational goals, conditioned by the effort’s ability to satisfy some individual needs. Motivation theories are classified into two groups: ‘content theories’ and ‘process theories’. Content theories explore what motivate people: that is, arouses and energize the behavior. The most famous content theories are Maslow’s need hierarchy, Herzberg’s two-factor theory, and McClelland’s three-factor theory. Process theories researched the specifics of the motivation process. Vroom’s expectancy theory and Adam’s equity theory are well known process theories. As the concept of motivation is reviewed, we should keep in mind that level of motivation varies both among individuals and within individuals at different levels. Among motivation theories to be re-viewed are those of Maslow, Herzberg, Hofstede, and Vroom. Maslow’s theory of motivation: Maslow, a behavioral scientist, is one of the most prominent writers in the area of human motivation. He developed the â€Å"Hierarchy of needs theory†. Maslow (1970) stated there is a connection between behavior of individuals and their needs, and the strongest â€Å"felt needs† determine behaviors of individuals at given times. Maslow’s approach was based on the assumption that the individual is the basic unit in a social organization that is capable of â€Å"life affirming and self -fulfilling† behavior. Maslow believed that work becomes a personal commitment and its accomplishment creates satisfaction and self- actualization and provides a way to achieve individual goals. Maslow categorized these â€Å"needs† into five levels; from the most primary needs of Physiological; Safety; Social at the base to the most secondary needs of Esteem and Self-actualization needs at the top. Basically, Maslow postulates that knowing the needs that employees are trying to satisfy, managers can help satisfy those needs so that employees can be satisfied and, then, motivated to work better. He believes that the lower needs are satisfied before an individual attempt to satisfy a higher level need in the hierarchy. Maslow’s need theory has received wide recognition, particularly among practicing managers. Its popularity can be attributed to the theory’s intuitive logic and ease of understanding. Unfortunately, however, few researches do not generally validate the theory. Maslow provided no empirical substantiation for the theory, and several other studies, which includes the studies of Lawler III and Suttle (1972), and Hall and Nongaim (1968) that sought to validate it found no support. Herzberg’s two-factor theory: Both Herzberg and Maslow agreed that if an organization met the safety and social â€Å"needs† of its employee group, the satisfaction and level of performance of the group would rise. Herzberg (1968) proposed the â€Å"Two-Factor† theory of motivation. He conducted research among 200 engineers and accountants regarding job satisfaction and dissatisfaction. The subjects were asked to think of a time when they felt good or bad in their work environment. Herzberg, after analyzing the responses, concluded that there are two groups of factors, which cause satisfaction and dissatisfaction in an organizational setting and work environment. Herzberg called the first group of factors â€Å"motivators† and the second group â€Å"hygiene†: The hygiene factors, also called maintenance factors, are of such a nature that their presence in the organization will not necessarily motivate an individual to work harder but the absence of which can create an unhealthy organizational environment. Hygiene factors, such as salary, company policy, supervision, job security, working conditions interpersonal relations, and status, are job context factors that help to maintain a healthy working environment. They do not motivate workers when pre-sent but workers can become dissatisfied when these factors are absent. The second set of factors-the motivators- are related to the job content of workers. The presence of these factors can motivate workers to perform better and their absence can result in dissatisfaction. These factors include achievement, recognition, advancement, challenging work, opportunity for growth, and higher responsibility. Herzberg maintains that both factors are important to the smooth running of an organization. The hygiene factor, even though they do not motivates, if absent creates a poor job attitude. However, an organization may have good working conditions, with adequate provision of hygiene factors, which are only job context, and workers may not be motivated. If adequate attention is paid to the motivators, which are job content related, workers may be motivated to work harder and produce more. Hofstede work-goals motivation theory: Hofstede (1980, 1990) postulated his motivation theory on 18 work-goals. The work-goals were classified into five major groupings or super goals as relating to the needs or goals of individuals in motivation. The super goals are: do a good job, ambition, cooperation and individuality, family and comfort and security. The five super goals are made up of these component goals among others: 1. Do a good job (challenging work, achievement, skill utilization). 2. Ambition (advancement, recognition). 3. Cooperation (good working relationships with colleagues, with boss). 4. Family and comfort (time for personal/family life; desirable living area). 5. Security (stable employment, welfare benefits) Vroom expectancy theory: Vroom approaches the issue of human motivation quite differently from the ways Maslow and Herzberg did. He holds that people will be motivated to pursue the achievement of a desired goal if: (1) they believe in the worth of the goal; and (2) they believe that their actions will en-sure the attainment of the goal. In a more detailed form, Vroom believe that a person’s motivation to perform will depend on the value the person places on the outcome of his efforts multiplied by his confidence that the efforts will actually help to desired goal; that is F = V * E Vroom’s theory shows that individuals’ have goals and are motivated towards actions that will ensure the achievement of these goals. As such, managers should communicate how employees goals, such as promotion, more pay, recognition, and so on, can be earned in terms of what behavioral patterns are known to employees, such patterns should form the basis for administering rewards. Otherwise problems will occur in terms of workers’ lack of confidence in organizational policy, and the result may be detrimental to good working environment. Culture and management discourse: The last decade has brought a renaissance of interest in cultural phenomena in societies and organizations. Re-searchers from a variety of disciplines have provided range of theoretical and analytical studies. Perhaps because of the different methodological and political orientations that distinguish these disciplines, the literature remains theoretically unintegrated – in a state of conceptual chaos. Before reviewing the relevant literatures about culture, and the impact of culture on motivation management, it is important to define culture. Culture is a common word and like all common words it comes with much conceptual baggage, much of it vague, some of it contradictory. Contemporary concepts of culture: Some management researchers subscribed to the view that sees culture as- a shared homogenous way of being, evaluating and doing-, which are ideas, shared by members of a cultural group. Others see culture as heterogeneous combining differentiated and dynamic subcultures, still, others see culture from a multi- fragmented perspective that bring ambiguity into culture discourse – which are vital to motivation. As numerous intercultural scholars have noted, each culture has its own unique â€Å"world-view† or means for making sense of the world (Zahama, 2000). Hofstede (2003) defines culture as the â€Å"software of the mind†, a collective phenomena, shared with the people who live in the same social environment. It is the collective programming of the mind, which distinguishes the members of one social group or category of people from another. According to Deresky (2003), culture comprises the shared values, assumptions, understandings and goals that are learned from one generation, imposed by the current generation, and passed on to succeeding generations. Hawkins et al. (2006) propagates that the main operational regime of culture starts by earmarking stated boundaries for individual behavior and by guiding the functioning of such institutions as the family and mass media. In a societal setup these boundaries are termed as ‘norms’. Further, norms are derived from cultural values. Given the commonalities among the various authors of culture quoted above, it is obvious that they concur that culture should be defined as that which is shared, harmonious, homogeneous, but the definitions disagree with what exactly is being shared or harmonious and homogeneous. Culture consists of patterns, explicit and implicit of and for behavior acquired and transmitted by symbols, constituting the distinctive achievements of human groups, including their embodiments in artifacts; the essential core of culture consists of traditions (that is, historically derived and selected) ideas and especially their attached values. From a more dynamic perspective, culture is conceived as being made up of relations, rather than as stable suggests that every individual embody unique combination of personal, cultural and value systems. This implies that national cultures, corporate cultures or professional cultures, for example, are seen as symbolic practices that only come into existence in relation to, and in contrast with, other cultural communities. Levels of culture: As almost everyone belong to a number of different groups and categories of people at the same time, people unavoidably carry several layers of values within themselves, corresponding to different levels of culture. For example: A national level according to ones’ country. A regional and/or ethnic and/or religious and/or linguistic affiliation level, as most nations are composed of culturally different regions or ethnic or religious or language groups. A gender level, according to whether a person was born as a girl or as a boy. A social class level, associated with educational opportunities and with a person’s occupation or profession. A generation level, which separates grandparents from parents from children; for those who are employed, an organizational or corporate level according to the way employees have been socialized by their work organization In modern society, they are often partly conflicting: for example, religious values may conflict with generation values; gender values with organizational practices. Conflicting values within people make it difficult to anticipate their behavior in a new situation. These socialization processes or levels of culture are more ways of doing things, or practices, as opposed to fundamental assumptions about how things are. In the center is a system of societal norms, consisting of the value systems shared by major groups of the population. Their origins are in a variety of ecological factors (in the sense of factors affecting the physical environment). The societal norms have led to the development and pattern maintenance of institutions in society with a particular structure and way of functioning. These include the family, education systems, politics, and legislation. These institutions, once they have become facts, reinforce the societal norms and the ecological conditions that led to them. In a relatively closed society, such a system will hardly change at all. Institutions may change, but this does not necessarily affect the societal norms; and when these remain unchanged, the persistence influences of a majority value system patiently smooth the new institutions until their structure and functioning is again adapted to the societal norms. Change comes mainly from the outside, through forces of nature (change of climate, silting up of harbors) or forces of man (trade, colonization, scientific discovery). The arrow of outside influences is deliberately directed at the origins, not at the societal norms themselves. It is believed that norms change rarely by direct adoption of outside values, but rather through a shift in ecological conditions: technological, economical, and hygienic. In general, the norm shift will be gradual unless the outside influences are particularly violent (Hofstede, 1980a). THEORETICAL BACKGROUND: A survey study was carried out in five different European and African countries by a The Research and Development Unit of Euro-African Management Re-search Centre (E-AMARC – Maastricht-Paris-Brussels-Stirling) to know the impact of differences in cultures on motivational factors. The European countries were France, Italy, Nether-lands and Scotland, while the African country involved in the research was Nigeria. The questionnaire used as a base the ‘Value Survey Model’ developed by Hofstede The research aimed at comparing motivation management values across five countries. For this purpose, written survey questionnaire was used. The questionnaire tried to obtain a fair representation of the opinions of two categories of respondents: Managers (everybody leading the work of others), non-managers (higher educated employees). The questionnaire contained items about the manager’s motivation-related values and perceptions. Only the questions found significantly relevant for the understanding of the effect of culture on management motivation practices were reported and examined in the study. The research included,The survey questionnaire contained a number of questions aiming at understanding â€Å"what makes people thick†. Table 2 presents the data on Maslow, Herzsberg, Hofstde and Vroom motivation factors as they are perceived to influence motivation by the respondents. This research project describes the results of a survey study of five countries; France, Italy, Scotland, Netherlands and Nigeria. DISCUSSION: It has often been said and discussed that the motivational factors does not have the same prominence in different cultures. In the survey, questionnaire contained a number of questions aiming at understanding â€Å"what makes people thick†. The table presents the data on Maslow, Herzsberg, Hofstde and Vroom motivation factors as they are perceived to influence motivation by the respondents. The research project describes the results of a survey study of five countries; France, Italy, Scotland, Netherlands and Nigeria. The results obtained from the research confirmed that the cultures of France, Italy, Scotland and Netherlands as measured by the motivation-related values and desires of the respondents were different. Examination of responses on the motivation-value factors from the research reveals that the Italians ranked â€Å"have challenging tasks, have freedom to adopt their own approach to tasks, make contribution to the success of their organization, live in desirable area for self and family, and to have good working relationships with direct superior† as the five most important motivation-value factors. To â€Å"serve your country, have little tension and stress on the job, work in a well-defined job situation, have opportunity to help others and work in prestigious and successful organisation† as the five lest important motivation-value factors. The French respondents ranked â€Å"have challenging task, live in desirable area, freedom of approach to tasks, cooperation with others, and good working relations with superior† as the five top motivation-value factors. They ranked â€Å"serve your country, have little tension and stress on the job, work in a prestigious and successful organisation, have security of employment and well-defined clear job situations† as the five lest motivation-value factors. The Scottish respondents ranked â€Å"cooperation with others, live in desirable area, challenging tasks, have good relationship with superior and to have freedom of approach to tasks† as the five top motivation value factors. They ranked â€Å"serve your country, to have little tension and stress on the job, to have opportunity to helping others, to have well defined and clear job situations and work in prestigious and successful organisation† as the five lest motivation-value factors. The Dutch on their part ranked â€Å"live in desirable area, cooperation with others, have good physical working conditions, have good working relationships with direct superior and have opportunity for higher earnings† as the five top motivation-value factors. They ranked â€Å"serve your country, have little tension and stress on the job, have opportunity to helping others, to be consulted by direct superior and to have variety and adventure on the job† as the five lest motivation-value factors. To the Nigerian respondents, they ranked â€Å"make contribution to the success of their organisation, to have challenging tasks, have security of employment, opportunity for higher level jobs and cooperation with others† as the five top motivation-value factors. They ranked †have little tension and stress on the job, have variety and adventure in the job, to be consulted by direct superior, work in prestigious and successful organisation and opportunity for helping others† as the five lest motivation-value factors. The difference in the ranked order of the work-goals among the four European country respondents is of little significance. Though there is not much difference among these countries, there are significant differences when compared with the African-Nigerian respondents. In a collectivist society like Africa-Nigeria, goals like security of employment, contribution to the success of organisation, opportunity for advancement to higher level jobs and earnings have symbolic cultural and economic values that add to their rated importance. Some of the value clearly relate to ‘motivation factors’ and others relate clearly to ‘hygiene factors’ in Herzberg terms. For example, variety and adventure in the job, challenging job, freedom on the job, recognition and opportunities if they refer to advancement, not merely to earnings, higher salary, all clearly relate to ‘motivation factors’. On the other hand, factors like opportunity for higher salary, good physical working conditions, security, and good relationship with superior are clearly hygiene factors. However, some factors like clear job description, cooperation and challenging tasks sit on the fence and may deflect one way or the other depending on the tasks and situations at hand. Comparing the five highest motivational factors to Herzberg’s two-factor theory, the European respondents ranked, challenging tasks, desirable living area, freedom of approach to job, working relation-ships with superior and cooperation with others, are motivator factors. For the African Nigerian respondents, contribution to success of organisation, security of employment, advancement to higher level jobs and earnings are hygiene factors. Herzberg stated that to the degree that motivators are present in a job, motivation will occur. The absence of motivators does not lead to dissatisfaction. Further, he stated that to the degree that hygiene’s are absent from a job, dissatisfaction will occur. When present, hygiene’s prevent dissatisfaction, but do not lead to satisfaction. In this study, the lack of challenging task for the respondents would not necessary lead to dissatisfaction. Higher earnings for the respondents than what they believe to be fair may lead to job dissatisfaction. Conversely, the respondents will be motivated when they are engaged in challenging tasks but will not necessarily be motivated by higher earnings. The result of this study supports the idea that what motivates employees differs from organisation to organisation and from country to country given the context in which the employee works. What is clear, however, is the emphasis given to the ranked order of the most important motivation value factors across cultures. Implications for management and organization: One crucial question to be answered is what motivates employees to work effectively and productively? One of the answers can be, challenging jobs, which allows a feeling of achievement, responsibility, growth, advancement, enjoyment of work itself and earned recognition, have not appeared as very motivating factors as was the case with most studies of this nature conducted in the West. This difference may be due to cultural influences. The West tends to be individualistic while Africa-Nigeria and most other African countries tend to emphasize the social aspects of a job situation. In Africa-Nigeria, clear job description, which ranked 8th position, is a very strong motivator and this seems to be consistent with traditional African value concern for paternalistic superior-subordinate relations. Similarly, contribution to the success of one’s organisation to the African-Nigerian respondents is more important than to be consulted by one’s boss in his decisions and freedom of approach to job. To make a contribution to the growth of one’s organisation is rather a static affair ‘present’ orient-ted and suggests a group of well-motivated employees’ who would want to be consulted by their superiors and get involved with the effectiveness of the organisation and cordial human relationships The ranked order of the motivation value factors of the respondents provides very useful information for management and the employees. Knowing how to use information provided by the study results in motivating employees is a complex task. The strategy for motivating employees depends on which motivation theories are used as a reference point. If Hertzberg’s theory is followed, management should begin by focusing on earnings and job security (hygiene factors) before focusing on interesting work and full appreciation of work done (motivator factors). If Vroom’s theory is applied, management should begin by focusing on challenging tasks and desirable living area for the employees in effort to achieving organizational goals and objectives. If Hofstede’s work-goal theory is applied, management must focus on advancement to higher level jobs, earnings, and security of employment in order to motivate the employees to effectively become satisfied and productive. A comparison of the results provides some interesting in-sight into motivation values across cultures. Challenging tasks, which ranked as number one motivator for Italy and France, ranked number two for Nigeria and number three for Scotland, is a self-actualizing factor. The number one ranked motivator, contribution to success of organization, is a physiological factor. According to Maslow, if management wishes to address the most important motivational factor of employees, challenging tasks, physiological, safety, social, and esteem factors must first be satisfied. If management wished to address the second most important motivational factor of employees, opportunity for higher earnings, increased salary would suffice. Contrary to what Maslow’s theory suggests, the ranges of motivation factors are mixed in this study. Maslow’s conclusions that lower level motivation factors must be met before ascending to the next level were not validated in this study. It is perhaps very interesting to note that the rank order of the factors by the African-Nigerian respondents seems to be gravitating towards ‘hygiene and maintenance factors’. Of the seven factors most highly ranked, only ‘security and earnings’ are indisputably motivation factors in Herzberg terms. One of the points to observe from the table is the relative low position (10th and 17th) scored by â€Å"freedom on the job† and â€Å"to be consulted by direct superior† respectively for the African-Nigerian respondents. Variety and adventure on the job, which is associated to recognition, scored the 16th position. All these factors are motivation factors by Herzberg and host of other western theorists and should have scored much higher. The fact that they did not suggests that the respondents have other priorities and we may have to look into culture and environment for further explanations. The results of this study indicate that job context is more important than job content. Organizational control or interpersonal factors (job-context factors such as co-operation, security, opportunity, contribution and earnings), for the most part, received high-ranking more than internally mediated factors (job-content factors such as success, consultation, freedom and the job itself). The results suggest therefore that efforts to motivate the African- Nigerians should focus on job context rather than on job content. Changes in nature of organizational control factors or interpersonal factors are likely to be more valued than changes in the work itself. Work enrichment programs that help the respondents function as members of a group, and which emphasize formal rules and structures, are more likely to motivate them in an extrinsic oriented society of Nigeria, where satisfaction tends to be derived from contribution and security, than in Italy, France, Scotland and the Netherlands where the job itself is more valued. The results suggest that the African-Nigerian respondents may be effectively motivated by the hygiene factors as long as these factors explicitly meet their personal and family needs. The results presented also suggests that the Italian, French, Scots and the Dutch’s respondents ranking of motivation-value factors, all corresponding to â€Å"higher† Maslow needs. On their part, the African-Nigerian correspondents’ ranking of the motivation-value factors corresponding to â€Å"low† Maslow needs. These findings illustrate that cultures and organizational work settings may have dramatic effect on motivation values across cultures. The empirical evidences that result from this research have shown that the different management theories of motivation in the form they have been developed and applied in the West may not or partially fit culturally in Africa. The similarities and differences among the five country respondents suggest that it make sense to study and compare western motivation values and traditional cultural values, beliefs, perceptions and attitudes among countries, regions and sub-cultures within the same country. This study calls for caution in importation and imposition of training and education practices that draw uncritically on Western motivation management theories and models without due sensitivity to the cultural differences and specificities of how motivation are conceived of and practiced in different cultures. It also calls for an indigenous approach that builds naturally on prevailing cultural norms and values, and for a closer examination and more detailed reporting and support for an appropriate, viable and feasible motivation management theory orthodoxy that is congruent with local environment. Finally, it is argued, based on the empirical evidence of this research results, that the generally accepted Wes-tern (most especially US) motivation theories like Maslow, Herzberg and Vroom may not be very appropriate for motivating employees in Africa-Nigeria and for universal formulating and theorizing on motivation management. Conclusion: The motivational factors that exist in one culture or country may not be present in another. For example, the elements that motivate individuals in an individualistic society vary from those that would motivate individuals in a collectivistic society. People in an individualistic culture tend to view themselves mainly in terms of their own self-interests, goals, and accomplishments and do not normally associate these factors with those of the group or organization with which they belong. The concept of self-actualization is far more prevalent in this type of culture. Conversely, people in a collectivistic culture generally do not partake in activities of a highly individual nature. They tend to align their personal goals and interests to those of the group or organization as a whole. The United States and France are examples of individualistic cultures, whereas Japan is a predominantly collectivistic culture. As mentioned earlier, different types of cultures require different types of motivation. In the same sense, different physical and economic conditions within various countries can influence the actualization of lower-level needs, which may hinder the development of higher-order needs. For example, in countries that are somewhat less developed the stress of everyday life and being able to provide the basic necessities becomes so overwhelming that individuals are unable to move beyond this stage and fulfill higher-order needs. In addition, countries such as Japan that experience high uncertainty avoidance seem to value the need for security more so than self-actualization needs in regards to enhancing work motivation. In contrast, countries such as the United States and France that are lower in uncertainty avoidance tend to pursue self-actualization needs due to the fact that their requirements for security are less complicated and met more easily. When deciding which type of reward programs would be most beneficial to Global Industries, Inc. and its members, several theories of motivation will need to be examined and then applied with reference to the local culture. References: Organizational behaviour – Stephen Robbins Managing organizations – RK Sharma, Sahashi K Gupta Management of Organizational Behaviour- Englewood Cliffs: Prentice Hall. www. academicjournals. org

Development of Modern Middle East Essay

The purpose of this paper is to give a synopsis of the life history and work of Muhammad, son of Abdullah, the prophet of Islam. It will also seek to address the persecutions he underwent at the hands of his own clan. Muhammad was and remains one of the most influential people the world has ever seen. He was a mortal, illiterate man who has changed world history and left an indelible mark on the history books. He was the last of the prophets and one of the few with scriptures. The scripture (Qur’an) is one of the most read and revered books on the face of the earth. His work has over one billion followers worldwide comprising people from all races, social status, sex and age. He acknowledged every prophet before him and discriminated against none (Qur’an 2:285). He was a human rights champion. In this paper Quraysh and/or Mecca will mostly refer to unbelievers in Islamic monotheism at the time of Muhammad. MUHAMMAD: – BIRTH and CHILDHOOD Muhammad the son of Abdullah and the grandson of Abdul Muttalib (leader of the Quraysh tribe and custodian of al-Ka’aba) is the prophet of the Islamic religion. Muhammad was born in Mecca in the year 570 c.e. which is also known as the Year of the Elephant. This is the year that Abrahah, the king of Abyssinia (modern day Ethiopia) sent a powerful force to destroy al-Ka’aba because he viewed al-Ka’aba as a rival since it was attracting more pilgrims than his newly constructed temple in Yemen. According to history, on approaching Mecca the lead elephant of Abrahah’s convoy refused to enter the city. Then birds filled the skies stoning the army with pebbles so much so that they had to retreat in defeat. Muhammad was a descendant of Abraham through his son Ishmael. His father Abdullah died few months before Muhammad’s birth. His mother Aminah sent him the countryside to be nursed and nurtured as was the custom in Arabia. It’s believed that the children learn the qualities of self-discipline, nobility, and freedom better in the countryside than in the urban areas. It also gave them the opportunities to be speakers of eloquent Arabic spoken by the Bedouin. Aminah did not have much money to pay for the care so most of the caregivers would not take Muhammad until she met Halimah a poor Bedouin woman who became Muhammad’s nurse. One day while playing with his child peers, two angels appeared to him in human form, laid him down, opened his chest and purified his heart. For fear of what might have happened next, Halimah and her husband Harith returned Muhammad to his mother. (Britannica) Aminah died when Muhammad was only six years old. His grandfather (Abdul Muttalib) took custody of him, then two years later Abdul Muttalib fell sick and suspected he may not survive the illness, so he asked his son Abu Talib to take charge of Muhammad. Abdul Muttalib had many sons some of whom were richer than Abu Talib but he was the kindest and most respectable among his brothers. Abu Talib treated him very well and respectfully. ADOLESCENT to MARRIAGE At a young age he joined Abu Talib’s caravan to Syria. On this Syrian trip a Christian monk (Bahira) saw the signs of prophethood on him, invited him and his uncle to dine with him. He saw the prophet seal on his back and told Abu Talib to protect him from the Jews and Christians because might kill him if they realize his was the foretold prophet to come after Jesus (Qur’an 61:6) And [mention] when Jesus, the son of Mary, said, â€Å"O children of Israel, indeed I am the messenger of Allah to you confirming what came before me of the Torah and bringing good tidings of a messenger to come after me, whose name is Ahmad.† But when he came to them with clear evidences, they said, â€Å"This is obvious magic.† Muhammad was said to be a young man of unusual physical beauty and generosity of character. He was revered in Mecca due to his sense of fairness and justice that people often went to him for arbitration, hence the title al-Amin (the Trusted One). His uncle Abu Talib recommended him to Khadija to work on her caravan. He did so well that Khadija retained his service and made him the head of her caravan and proposed marriage to him through her friend. They got married when Muhammad was twenty five years old and Khadija who was forty years old. During marriage they had two sons and four daughters. The two sons both died young and only Fatimah among the daughters grew up to have children of her own. At age thirty five, Muhammad took his cousin Ali who was five at the time into his household and raised him. He later gave his daughter Fatima to Ali in marriage and it was through this matrimony that his progeny came. (Britannica) All these time although an illiterate, he was not satisfied with the spiritual lives of the Meccans. He started retreating to the mountains for meditation. He has seen, heard, and dreamed of miraculous things and beings. He maintained in his mind that there must be a supernatural being somewhere who is responsible for all these creatures. (CARM) CALL to PROPHETHOOD Muhammad continued his daily retreat in the cave on the mountain. One day, generally believed to be the night of power (Laila tul Qadr) in Ramadan at age forty in the year 610 c.e. while in the cave on mount Hira, the archangel Gabriel appeared to him in human form and asked him to recite. Muhammad told the angel that he did not know how to read but Gabriel insisted he recite the name of thy Lord (Qur’an 96:1-5) â€Å"Read! In the name of your Lord (Cherisher and Sustainer), He who created — created man, out of a leech-like clot: Read! And your Lord is Most Bountiful. He who taught (the use of) the Pen, taught man that which he knew not.† The appearance of Gabriel to Muhammad confirmed his call to prophethood which also marked the beginning of Islam, and added another important chapter to Arab and world history. Among the first converts to Islam were his beloved wife Khadija, Ali his cousin and later son-in-law, and his friend Abu Bakr. The words that Gabriel taught him became the first verses (Ayat) of the scriptures (Koran) which later developed to one hundred and fourteen chapters arranged from the longest to the shortest except the opening chapter (al-Fatiha) which is short. The Qur’an was revealed in a period of twenty three years (610-632 c.e), the first thirteen years in Mecca and last ten in Medina. Although not arranged in chronological order, the shorter chapters are the early revelations. The Qur’an is one of the most revered and read books on earth today. It is the most sacred book for the Muslims; they believe it is God’s own words (the original copy in heaven) and that Muhammad is the last of the prophets hence the other title the â€Å"Seal.† In this case Muhammad and the Qur’an are both completely beyond criticism (reprimand) in the Islamic world. The Muslims will go any length to defend both regardless of the consequences. (Britannica) EARLY DAYS of ISLAM and PERSECUTIONS For the first three years Islam had about forty followers (Muslims). Muhammad and the Muslims faced a lot of persecutions at the hands of Mecca pagans, who viewed the new faith as a threat to their polytheistic lives, and the religions of their forefathers. He was still preaching in private even after three years. He preached a lot about kindness to the poor and the weak (women and children), equality of races, equality of men and women before God. Muslims started gaining ground slowly but surely. Since Mecca frequently had visitors, the elders feared that the new faith might quickly spread if strangers started accepting it, so they had to hatch a plan to stop the spread. They continue to defend their religion but offered little new to the challenge Islam brought to them. Abu Lahab (Muhammad’s uncle) and Abu Sufyan gathered eloquent poets from the tribes and started a propaganda war. The poets coined choice phrases and recited well-crafted verses to ridicule Muhammad and call into doubt the veracity of his beliefs. Muslim converts with poetic skill began to construct rebuttals and soon there were dueling poets all over the city. People began approaching the once highly respected Muhammad in the streets shoving and asking him to perform miracles (predict market prices, turn mountains into gold, make angels appear, and etc.) like the earlier prophets did. Many Qur’an verses came down to him to answer the many challenges he faced and those that question the authenticity of the Qur’an. Muhammad frequently reminded them that he was just a mortal man and the Qur’an was his miracle. Another thing that puzzled the opponents was that Muhammad was not a poet, and his sudden eloquence and verbosity was inexplicable. The Meccans admitted to the fact that Qur’anic verses were nice to listen to and its contents were impassioned and appealing. Some clan elders began sitting outside Muhammad’s window at night to hear him reciting his beautiful verses. They enjoyed the verses and knew that those verses could not have come from even the best poet let alone an illiterate man. This continued until they shamed each other into stopping because that will mean they are encouraging Muhammad and admitting that he was on the right path. (Emerick Yahiya) He continued (Qur’an 7:194-198) speaking against asking idols for help even though the idols could not see, hear, speak, or protect themselves. These Qur’anic verses made idol worship look foolish. These assertions did not settle well with the Quraysh, so they approached Abu Talib (head of the Banu Hasim) and asked him to stop Muhammad or relinquish his protection of him so they could take care of him because he attacks their religion which was Abu Talib’s too. Abu Talib knew that to take care of him meant they wanted kill Muhammad. Remembering the promise he made to his father to protect Muhammad he politely told the clan elders that he would continue to extend his clan’s protection to Muhammad. Muhammad was preaching that slaves were equal to their masters at a time when slavery was at its height in Arabia. This alarmed the Quraysh leaders which prompted them to reason with Abu Talib for the second time, they took along an able-bodied young man (Umarah) to be Abu Talib’s adopted son in exchange for Muhammad. Abu Talib strongly rejected the offer. Meanwhile Muhammad continued his preaching and people continue converting to Islam. (Emerick Yahiya) The Quraysh elders tried a third time to reason with Abu Talib only this with an ultimatum and that was â€Å"Stop Muhammad or we will fight him and you.† Abu Talib did not want to cause trouble for his clan, called Muhammad to a private meeting and said to him â€Å"Save me and save yourself.† Muhammad politely responded his uncle by saying â€Å"Uncle by Allah, if they put the sun in my right hand and the moon in my left and ordered me to give up this cause, I would never do it until either Allah has vindicated me or I perish in the attempt.† When the response was conveyed to the clan leaders, they ordered redoubling of efforts to persecute Muslims. Abu Talib assured him of his unflinching support no matter what he preached and called the Banu Hashim and Banu Abdul Muttalib clans to swear to an oath to protect Muhammad. The Quraysh then sent Utbah, a conciliatory Arab leader to Muhammad asking him to stop preaching his religion or at least make accommodation for idol worshipping, then the Meccans would compensate him whatever he wished. Muhammad recited Chapter 32 of the Qur’an, which outlines the truth of monotheism, Allah’s purpose for creation, and the way He chooses prophets to convey His message of salvation. Utbah was convinced that Muhammad was not crazy and that he should be left alone. Persecution of Muslims then increased to an alarming rate. Muslims were tortured, starved, left to die in hot desert sands, and even murdered. MIGRATION to MEDINA (HIJRA) Due to the persistent persecutions from the people of Mecca, Muhammad accepted the invitation from Yathrib (modern day Medina) to be the head of the city and arbitrator for the warring factions. He could also have freedom to practice and preach about his faith. He migrated to in the year 622 c.e. with his family and some followers. When he was leaving his house Muhammad recited (Qur’an 36:9) â€Å"We have covered them so they cannot see,† he slipped out passing unnoticed by the men assigned to kill him. He left his cousin Ali to sleep in his house. Upon arrival at Yathrib, he and his companions were welcomed with loud cry of delight; a chorus of girls sang a welcome song for them. From that day Yathrib was renamed Medina (city of the prophet). The migration is known as Hijra which also marked the beginning of the Islamic calendar. (CARM) Islam started growing rapidly as a dominant political force in Medina and Muhammad assumed the role of a de facto head of state. Both men and women (including but not limited to Safiya bint Abdul Muttalib, Asma bint Abu Bakr, and Fatima bint Muhammad) played important roles as activists and teachers to make a homeland for Islamic monotheism a reality. Many women began to vigorously support the new movement, for Islam presented a great leap forward in both women’s rights and status. Islam was now going through radical changes. The changes included opposition to idolatry, improving personal morality, establishing personal relationship with God, and regulations for public and social life. The Qur’an laid new rules for the conduct of business and commerce, the compulsory 2.5% welfare tax (Zakat) from annual savings to be given for the benefit of the poor and needy. Fasting (abstinence from worldly pleasure during daylight) in the month of Ramadan was established. The five daily prayers were now held in congregation in the mosque. (Mission Islam) With the arrival of Sawdah and marriage to Aisha, Muhammad started to establish a stable household in Medina. Sawdah was a widow of ********* and one of the early converts to Islam. She got married to Muhammad after the demise of Khadija. She was said to be a very kind and humorous woman. Aisha may have been twelve years or so at the time. She lived in her own apartment by the mosque and spent her leisure entertaining visitors and walking the streets of Medina. Aisha was a quick learner and soon became a sought-after teacher on Islamic issues as the years progressed. Sawdah also had her own apartment and did not encroach upon Aisha’s domain. She took the inexperienced Aisha under her wing and guided her in her role as a wife. (Inter-Islam) WARS against DISBELIEVERS Muhammad and his followers fought many wars against Islam’s foes from Mecca, Jews and the tribes. The first of the great wars was the â€Å"Battle of Badr.† The Muslims were outnumbered by Meccans almost three to one. The Meccan army was headed by Abu Jahl a staunch enemy of Islam and the person of Muhammad. The Meccans lost their camp and its wealth and supplies, and about fifty men including Abu Jahl and many other leaders who died in the war. The Muslims took about seventy Meccans prisoner. The Muslims had fourteen casualties. Muhammad announced that Allah’s help allowed them to win (Qur’an 8:9 and 8:17). While the Muslims continued to celebrate their win in Medina, the Meccans were humiliated by the Battle of Badr at home and wanted to revenge. This will mean a change of events for the Muslims (Qur’an 3:140) â€Å"If a wound hath touched you, be sure a similar wound hath touched the others. Such days (of varying fortunes) We give to men and men by turns: that Allah may know those that believe, and that He may take to Himself from your ranks Martyr-witnesses (to Truth). And Allah loveth not those that do wrong†. This leads to the Battle of Uhud. The Meccans used the proceeds from Abu Sufyan’s great caravan to procure weapons for next campaign against Muslims. They had three thousand well-armed fighters divided into three massive columns. The women’s group was led by Hind, Abu Sufyan’s wife who vowed not to mourn the deaths of her father, brother and uncles, and also promised not to sleep with her husband until she had her vengeance against the Muslims. Abu Sufyan trying to convince his wife of his own bravery also promised not to bathe until he defeated Muhammad. Many women decided to come along to encourage their husbands and fathers and watch the battle. Hind, Abu Sufyan’s wife stated â€Å"We will indeed accompany the army and no one can stand in our way or force us back into our homes, if the women were present at the Day of Badr soldiers running away would not have happened.† At the head of each Meccan regiment were men who wanted to see Muhammad dead. Among them were Khalid ibn al-Walid famous Meccan cavalry general who wanted glory and accolades. Abu Sufyan and his brother-in-law Ikhrimah, the son of Abu Jahl were seeking blood to fight for glory. The women made it clear that if their men struck down the enemy they would be embraced and w0uld spread rugs for them. If you turn your backs we will avoid you and we will never come back to sleep with you. (pbs.org) The Prophet instructed fifty archers to protect the Muslims backs and not to move from their posts until they saw the Muslims entering the enemy camp, if the Muslims were being beaten they should still stay at their posts and avoid trying to help so that the enemy could not come behind them. However, the archers left their posts allowing the enemy the chance to get behind them which caused the Muslims to be overwhelmed by the much larger enemy (Qur’an 8:27-28) â€Å"O you who have believed, do not betray Allah and the Messenger or betray your trusts while you know [the consequence]. But when he came to it, he was called, â€Å"Blessed is whoever is at the fire and whoever is around it. And exalted is Allah, Lord of the worlds.† The Prophet himself got struck by a thrown rock that knocked one of his teeth off and he fell to the ground. He was quickly surrounded by Muslims to protect him from the charging Meccans. The Prophet tried to get up but fell into a pit, Ali and another man lifted him out of the pit. The Muslims suffered about seventy casualties and many others were severely wounded, and the Meccans lost hundreds. However, the Muslims admitted defeat because of high number of casualties and wounded including the prophet with regard to the size of the ir army. The Meccan women led by Hind enraged by their near defeat began to mutilate and deface the fallen Muslims. They cut off noses and ears and made them ornaments or necklaces moving over dead bodies like ghouls. Hind found Hamza’s dead body, ripped open his chest and chewed on his liver, fulfilling her vow. Hamza was Muhammad’s uncle and the one who killed Abu Jahl, the father of Hind. Hamza was killed by a slave whom Hind promised to set free if he killed Hamza. (Emerick Yahiya) After the battle of Uhud the Muslims position in Medina was precarious and the hypocrites capitalized on this situation to strengthen their position. Most of the tribes were now emboldened since they realize that the Muslims were not invincible. Many times, Muslims who were sent on missions got massacred and this brought about a lot of sadness among surviving compatriots. Muhammad explained the change in their fortunes as God’s way of testing their resolve and sincerity. (Qur’an 2:15 5-156). The Jews who had signed treaties with the Prophet broke the terms of the treaties and they were exiled from Medina. The Jews incited other tribes and Mecca to go to war with Muslims to wipe out Islam. The tribes and Meccans made up an army of about ten thousand fighters to attack the Muslims. The Prophet and other Muslims dug a trench at the south entrance of the city to protect Medina from the menacingly large army attack, since the other side was Mount Uhud and the back was the Jewish fortresses. The army arrived but could not enter the city of Medina so they laid siege for three weeks. This was called the siege of Medina or Battle of the Trench. This was a difficult time for Muslims because their food supply was running out and their Jewish neighbors (Banu Qurayza) had cut the food supply. However, after about three weeks in the cold desert nights the army started feeling weary. One night a raging winter storm befell the army, and the weather was so harsh that they decided to leave. (Emerick Yahiya) CONQUEST of MECCA and PASSING of the PROPHET Despite all the troubles Muslims faced, Islam was steadily growing. In the year 628 c.e the Muslims and the Quraysh signed the treaty of Hudaybiyah, and the Muslims defeated the Jews at the battle of Khaybar. In the year 629 Muhammad led a lesser pilgrimage to Mecca and Khalid ibn Walid converted to Islam. In the year 630 c.e the prophet marched unto Mecca with over ten thousand followers. They faced very little resistance from the Meccans. The prophet and the Muslims destroyed and removed all the idols that filled al Ka’aba and established prayers in the place. Abu Sufyan the last strongest Quraysh leader converted to Islam. (Emerick Yahiya) In the year 632 c.e the prophet went to Mecca with over one hundred thousand followers to perform farewell pilgrimage (hajj). This was to be his last hajj and this was where gave the farewell sermon (address), which reads â€Å"O People, lend me an attentive ear, for I don’t know whether, after this year, I shall ever be amongst y ou again. Therefore listen to what I am saying to you carefully and TAKE THIS WORDS TO THOSE WHO COULD NOT BE PRESENT HERE TODAY. O People, just as you regard this month, this day, and this city as Sacred, so regard the life and property of every Muslim as a sacred trust. Return the goods entrusted to you to their rightful owners. Hurt no one so that no one may hurt you. Remember that you will indeed meet your LORD, and that HE will indeed reckon your deeds. ALLAH has forbidden you to take usury (Interest), therefore all interest obligation shall henceforth be waived†¦ Beware of Satan, for your safety of your religion. He has lost all hope that he will ever be able to lead you astray in big things, so beware of following him in small things. O People, it is true that you have certain rights with regard to your women, but they also have right over you. If they abide by your right then to them belongs the right to be fed and clothed in kindness. Do treat your women well and be kind to them for they are your partners and committed helpers. And it is your right that they do not make friends with any one of whom you do not approve, as well as never to commit adultery. O People, listen to me in earnest, worship ALLAH, say your five daily prayers (Salah), fast during the month of Ramadan, and give your wealth in Zakat. Perform Hajj if you can afford to. You know that every Muslim is the brother of another Muslim. YOU ARE ALL EQUAL. NOBODY HAS SUPERIORITY OVER OTHER EXCEPT BY PIETY AND GOOD ACTION. Remember, one day you will appear before ALLAH and answer for your deeds. So beware, do not astray from the path of righteousness after I am gone. O People, NO PROPHET OR APOSTLE WILL COME AFTER ME AND NO NEW FAITH WILL BE BORN. Reason well, therefore, O People, and understand my words which I convey to you. I leave behind me two things, the QUR’AN and my example, the SUNNAH and if you follow these you will never go astray. All those who listen to me shall pass on my words to others and those to others again; and may the last ones understand my words better than those who listen to me directly. BE MY WITNESS O ALLAH THAT I HAVE CONVEYED YOUR MESSAGE TO YOUR PEOPLE.† After the prophet concluded his final sermons the following qur’anic (ayat) verse was revealed to him (Quran 5:3) â€Å"This day have I perfected your religion for you, completed My Grace upon you, and have chosen Islam for you as your religion.† Muhammad died in the year 632 c.e. after a short illness two years after he conquered Mecca and destroyed the idols in al-Ka’aba. He was buried at Medina in the Mosque (Masjid Nabawi). â€Å"There is no forcing anyone into this way of life. Truth stands clear in the from error† (Qur’an 2:256) Sources Gelvin James L, (2011) The Modern Middle East- A History, Oxford University Press, New York Emerick Yahiya, (2002) The Life and Work of Muhammad, Alpha Books, Indianapolis Britannica Online Encyclopaedia- Muhammad (The Prophet of Islam). Retrieved on September 23, 2012 www.britannica.com/EBchecked/topic/396226/Muhammad PBS-islam: Empire of Faith-Profiles-Muhammad. Retrieved on September 25, 2012 www.pbs.org/empires/islam/profilesMuhammad.html Christian Apologetics and Research Ministry (CARM). Retrieved on September 30, 2012 http://www.carm.org/muhammad Inter-Islam Home. Retrieved on October 12, 2012 www.inter-islam.org/Biographies Mission Islam. Retrieved on October 15, 2012 www.missionislam.com/knowledge/zakat.htm

Cundo es posible trabajar con visa F-1 de estudiante

Cundo es posible trabajar con visa F-1 de estudiante Estudiar en los Estados Unidos es caro, por eso para los estudiantes internacionales con una visa F-1 es importante saber quà © opciones tienen para trabajar legalmente y asà ­ sufragar parte de sus gastos. En este artà ­culo, adems de explicar los requisitos para las 4 opciones de trabajo se hace referencia a otras opciones para obtener ayuda econà ³mica. Y al final se mencionan opciones migratorias que permiten quedarse al finalizar los estudios y tambià ©n quà © error no se debe hacer ya que puede salir muy caro. Trabajar con una visa F-1 de estudiante dentro del campus La primera opcià ³n para trabajar se presenta en el mismo lugar donde se est estudiando. Y es que los  estudiantes con una F-1 que està ©n estudiando a tiempo completo pueden trabajar siguiendo estas reglas: Tiempo:  trabajar un mximo de 20 horas semanales, excepto en vacaciones que pueden trabajar a tiempo completo Lugar: en campus significa eso pero tambià ©n admite que sea fuera, siempre y cuando el empleador sea una institucià ³n que tiene una relacià ³n de afiliacià ³n con la universidad o college, seminario, conservatorio, en el que el estudiante cursa sus estudios. Por ejemplo, otra universidad o un laboratorio. Tipo: el trabajo que se desempeà ±a tiene que estar relacionado de algà ºn modo con servicio a estudiantes. Por ejemplo, trabajo en bibliotecas, librerà ­as, etc. Permiso: tiene que contarse con la autorizacià ³n previa del Oficial Designado en la Escuela (DSO, por sus siglas en inglà ©s). Cundo: comenzarse a trabajar hasta 30 dà ­as antes de comenzar el programa acadà ©mico. Pero una vez que à ©ste finaliza, asà ­ debe ocurrir con el empleo. La excepcià ³n son los casos en los que se cambia de programa.   Trabajar fuera del campus con una visa F-1 por necesidad econà ³mica En este caso es necesario cumplir con un mayor nà ºmero de requerimientos, como: Tener un estatus vlido de estudianteEstar cursando a tiempo completoLlevar al menos un aà ±o acadà ©mico completo con la visa F-1 Necesidad econà ³mica urgente en casos como pà ©rdida sin culpa de puesto de empleo en el campus, cambios en la cotizacià ³n de la divisa del paà ­s del estudiante, facturas mà ©dicas, pà ©rdida de la ayuda financiera u otros gastos inesperados. Si se da alguno de esos casos y no es posible encontrar empleo dentro del campus, el estudiante debe dirigirse al Oficial Designado en la Escuela (DSO, por sus siglas en inglà ©s) para que este comunique la situacià ³n a las autoridades migratorias mediante el sistema SEVIS. Asimismo, el DSO proporcionar una certificacià ³n que debe enviarse al Servicio de Inmigracià ³n y Ciudadanà ­a (USCIS, por sus siglas en inglà ©s) junto con la planilla I-765 y el pago de la cuota correspondiente para obtener asà ­ un permiso de trabajo. Es conveniente incluir todo tipo de documentacià ³n que sirva de apoyo a la razà ³n que se alega para solicitar ese permiso, (en inglà ©s. Este es un modelo de carta para certifica la traduccià ³n). Entrenamiento prctico curricular (CPT, por sus siglas en inglà ©s) Se trata de prcticas pagadas que tienen que estar relacionadas con el grado que cursa el estudiante. Tienen que estar aprobadas por el DSO.   Pueden ser a tiempo parcial (menos de 20 horas a la semana), o, en à ©poca de vacaciones a tiempo completo (ms de 20 horas semanales). Hay que tener en cuenta que si a lo largo de sus estudios el estudiante completa ms de un aà ±o CPT a tiempo completo, al licenciarse (egresado) no podr disfrutar de un OPT. Entrenamiento prctico opcional (OPT, por sus siglas en inglà ©s) Se puede realizar durante los estudios de licenciatura, maestrà ­a o doctorado o al  finalizar los mismos.  Estas  son las reglas  para la OPT. El permiso de trabajo en este caso tiene una duracià ³n mxima de 1 aà ±os, si bien en ciertos campos relacionados con las Ciencias y la Tecnologà ­a se puede prorrogar hasta los 17 meses. A tener en cuenta cuando se trabaja Si se trabaja, el DSO proporcionar la documentacià ³n necesaria para solicitar una tarjeta del Nà ºmero del Seguro Social. Al trabajar, hay que reportar los ingresos y, en su caso, pagar impuestos. Si se trabaja sin permiso, eso es una violacià ³n migratoria, que puede tener consecuencias muy serias. Caminos para quedarse en USA trabajando al finalizar los estudios universitarios La mayorà ­a de los estudiantes internacionales regresan a sus paà ­ses de origen. Pero un buen nà ºmero se quedan, al menos temporalmente, al lograr obtener una visa de trabajo, generalmente una H-1B para profesionales, siendo muy solicitadas por los profesionales en el sector tecnolà ³gico. Si bien no son las à ºnicas visas de trabajo disponibles. Adems, en el caso de mexicanos, hay que destacar las visas TN para profesionales, que abren puertas sin tener los inconvenientes de cupo mximo de las H-1B que en la mayorà ­a de los casos dejan sin anualmente a miles de candidatos con patrocinador. Asimismo, tambià ©n es posible conseguir una tarjeta de residencia (green card) ya que las empresas pueden patrocinar por razà ³n de trabajo. Estas son las empresas que ms trabajadores esponsorizan. Finalmente, tambià ©n es posible quedarse en Estados Unidos en casos de ajuste de estatus por matrimonio o similares. Cà ³mo conseguir dinero para pagar por los estudios en Estados Unidos El camino ms transitado por los estudiantes es el de buscar y obtener becas. Estas pueden ser de instituciones o empresas del paà ­s de cada uno o tambià ©n de Estados Unidos, ya que hay muchas de ellas que no excluyen a los estudiantes internacionales, por ejemplo, à ©stas  de universidades de à ©lite. Casi todas las universidades tienen sus propios paquetes y sus reglas de cunto y a quià ©n pueden becar. Y tambià ©n existen instituciones que brindan becas por temas, dependiendo de quà © se estudia o quà © proyecto o trabajo se presenta. Tambià ©n existe la posibilidad de pedir crà ©ditos para estudiante y, finalmente, tambià ©n se puede considerar la posibilidad de realizar parte de los estudios universitarios en community colleges, que resultan ms asequibles, entre otra ventajas que brindan. Quà © errores deben evitar los estudiantes internacionales En primer lugar, no olvidar que trabajar sin permiso es una violacià ³n migratoria. Si hay una denuncia que puede ser anà ³nima o por cualquier otra razà ³n Inmigracià ³n se entera las consecuencias van a ser graves. Y en segundo lugar, recordar que los estudiantes internacionales necesitan una visa para estudiar a tiempo completo. Es cierto que las instituciones educativas admiten a indocumentados. Pero de lo que se trata es de precisamente no acabar en esa categorà ­a migratoria por no utilizar la visa correcta. Esto es relativamente frecuente en los casos de estudiantes internacionales que cursan la high school en Estados Unidos y por errores de este tipo acaban sin visa ellos y sus padres. Este es un artà ­culo informativo. No es asesorà ­a legal.