Bullying Essay Example | Topics and Well Written Essays - 750 words - 3

Bullying - Essay Example All of this came about because of one simple thing: I was teased. The experience of being bullied, even though it was not very intense, had a profound effect on my life after that point. Indeed, bullying is one of the most devastating social experiences many children, teens, and young adults face across the world today. According to the American Academy of Child and Adolescent Psychiatry, fully half of all children in public school systems will experience some sort of bullying at some point in their lives. This bullying can range from verbal teasing, as I experienced, to much more vicious physical and emotional abuse that can have a serious impact on the victim’s mental and physical well-being. Bullying during a child’s teenage years can take a heavy toll, and lead to depression, drug use, and stunted social development well into that person’s adult life. In severe cases, the victim may even commit suicide. As technology advances and more people become users of social media websites such as Facebook or MySpace, a new type of bullying has emerged. This is cyber-bullying, the use of virtual tools or places to insult and degrade a victim instead of doing it in person. This can be as simple as a text message, or as complicated as creating a fake social network account and making the victim believe you are their friend, before cruelly insulting them and utterly destroying their faith in other human beings. This was the case with Megan Meier, who hanged herself after the mother of one of her friends created a fake account and pretend to be a boy she liked, only to constantly insult her and tell her she was worthless. Clearly, then, bullying of all sorts is a serious problem. It is not only a problem I myself has experienced, but one which affects communities the world over. It is also a problem which communities need to tackle as communities, and not as individuals. There are several ways

Tobacco Targeting Children Essay Example for Free

Tobacco Targeting Children Essay Tobacco is one of the main products that affect our children today. Companies that distribute these products do not think about who is getting affected by their product, but think about the profit they will make from selling their product. Big companies like Philip Morris who sell Marlboro, Basic, Virginia Slim and many other types of tobacco target young adults. Gene Emery quoted the amount spent on tobacco advertising is targeting youngsters. Some points Gene Emery presents are quiet different than what I believe. From working at my previous store that I owned in Sacramento, during these eight years, I didnt recognize some of the points Gene Emery brings out. Gene Emery suggests that they found the amount spent to advertise three brands popular with young people- Camel, Marlboro and Newport- in youth-oriented magazines increased immediately. The first point I would like to point out is that Gene Emery targets young people and also said that brands for adult-oriented products like Basic, Winston or Virginia Slims spend less money on advertising because they target only adults. He says that certain products are for young people while some are for adults. The way he presented his idea was false because from my past experience, I have realized that Newport cigarettes targets African Americans, Marlboro targets originally Asians, Camel cigarettes targets construction workers, Virginia Slim targets women and Basic targets the less fortunate who cant buy Marlboro. Dont get me wrong that I am defend the tobacco companies, I am actually against this. Philip Morris spend more money on ads for Marlboro than Basic because Marlboro is more popular and brings in more profit than Basic does. When we deal with children, we have to be cautious about everything we do. Some adults who smoke, do not realize that their children are getting affected by them. Gene Emery believes that the advertising is to blame. I am agreeing with him, but we should not also forget the family actions in front of their children. In order to prevent our children to smoke, we should start at home. The parents have a great responsibility to act right in front of their kids like put out the cigarette they see their child coming through the door or to try to even stop smoking. I was raised with a family that does not smoke. We are eight girls and one boy and still none of us smoke till now because my family knew how to act and set the perfect role model for us. I am trying to do the same thing for my two boys. I tell them that smoking is awful and it makes you sick and die and whenever they see somebody smoking they say that this person is stupid because he is hurting himself. The laws in this country protects our children; in order for oneself to buy any tobacco, they have to be 18 years of age or older. There is also an agreement to stop promoting cigarettes to children. This agreement was passed in 1998. Attached to this paper is the lawsuit to control tobacco companies. Also, attached to this paper is an article that differs the US laws with other country like Australia and Britain. In my country, the government supports tobacco companies. Ads are placed everywhere about tobaccos, places like TVs, radios, in the street, magazine covers and they also made candys for kids that looks like cigarettes. I believe that the American children are lucky to have such great laws to protect them and that anybody can sue them if something went wrong. Difficult as it may be for tobacco control advocates to demand accountability, tobacco control programs will not survive if the nongovernmental organizations that care about the program will not protect it. The preservation of the intent and spirit of these programs will not occur simply because an initiative is approved by the voters. This approval is a powerful force, but it must be used effectively by those who accept the responsibility for defending the public interest. Exercising oversight over the elected and appointed officials who had authority over the tobacco control program was even more challenging for the public health groups than getting the program enacted. In the years immediately following an election or legislative action to create a tobacco control program, the effort to keep the will of the voters before the Legislature is not difficult, since both the press and the public are likely to be paying attention. But voter approval is likely to become less obvious and thus less powerful over time, and tobacco control advocates need to seek ways to keep the public informed and involved on the tobacco issue. If advocates instead retreat to playing only the insider political game, they will probably fail. They must be willing to withstand and embrace the controversy that the tobacco industry and its allies will generate. Appendix B Important California Tobacco Control Events April 1977 Berkeley passes an indoor air ordinance. November 1978 Proposition 5 (statewide initiative covering clean indoor air and Research Accounts until 1996, passes. SB 493 sought to issues) is defeated. November 1980 Proposition 10 (statewide initiative covering clean indoor air issues) is defeated. December 1980 Californians for Nonsmokers Rights forms to pass local clean indoor air ordinances. November 1983 Proposition P (San Francisco referendum) is defeated; smoke-free workplace law remains on the books. November 1988 Proposition 99 (statewide initiative) passes.

Existentialism in Albert Camus The Plague and Samuel Becketts Waiting

All of the characters in The Plague and Waiting For Godot exist in their fictional worlds. However, none is able to explain why. Neither work gives the reader an explanation of human existence except to say that humans exist. Providing an answer to the question of existence would constitute a paradox. To an existentialist, if you answer the question, then you've missed the whole point. Existentialism is a philosophy that emphasizes the uniqueness and isolation of the individual experience in a hostile or indifferent universe, regards human existence as unexplainable, and stresses freedom of choice and responsibility for the consequences of one's acts (Bigelow 134). Basically, existentialism addresses man's existence. An existentialist believes that man does not exist under God or as part of a society or race. Man does exist, and that is all. An explanation as to why man exists cannot be found. Finally, an individual exists not as a function of a greater good or evil; thus, the individual is free to live his life (135). Existentialism as a literary movement is most often associated with post World War II France. The images that come to mind are of Frenchmen with uncombed beards, smoky basement cafes, and beatniks conversing with one another on the subject of despair between sips of absinthe. However, many of the most prominent existentialist writers had rigorous and significant experiences in the Resistance during the Nazi occupation of France (Lottman 54). Out of true despair they formed ideas and posed questions of great importance. They sought to understand and explain human existence. They concluded that existence is to be acknowledged, but can never be explained. Two existentialist works are Samuel Beckett's Waiti... ... them to reevaluate their relations to others and to question their own existence. At first, most citizens assume that they will not get the plague, but they soon realize that even they are not immune to it. In this way they question their own humanity and are faced with something bigger than they have ever contemplated. They, like Vladimir and Estragon, are unable to come up with answers. All of the characters in The Plague and Waiting For Godot exist in their fictional worlds. However, none is able to explain why. Neither work gives the reader an explanation of human existence except to say that humans exist. Providing an answer to the question of existence would constitute a paradox. To an existentialist, if you answer the question, then you've missed the whole point. The key is in asking the question. The realization is in accepting that there is no answer

Internet and Intranet Connectivity Through Wireless Local Area Network (Wlan)

CHAPTER 1 Introduction Chapter 1 Introduction 1. 1 What is WLAN? 1. 1. 1 WLAN Wireless Local Area Network (WLAN) is a kind of local area network which established using a wireless link between the service providers and the clients using some wireless equipment. This network development is based on the IEEE 802. 11 standard. 1. 1. 2 IEEE 802. 11 IEEE 802. 11 denotes a set of Wireless LAN/WLAN standards developed by working group 11 of the IEEE LAN/MAN Standards Committee (IEEE 802). The term 802. 11x is also used to denote this set of standards and is not to be mistaken for any one of its elements. There is no single 802. 1x standard. The term IEEE 802. 11 is also used to refer to the original 802. 11, which is now sometimes called â€Å"802. 11 legacy† [1]. The 802. 11 family currently includes six over-the-air modulation techniques that all use the same protocol. The most popular techniques are those defined by the b, a, and g amendments to the original standard; security was originally included and was later enhanced via the 802. 11i amendment. 802. 11n is another modulation technique that has recently been developed; the standard is still under development, although products designed based on draft versions of the standard are being sold. Other standards in the family (c–f, h, and j) are service enhancements and extensions or corrections to previous specifications. 802. 11b was the first widely accepted wireless networking standard, followed by 802. 11a and 802. 11g [1]. 802. 11b and 802. 11g standards use the 2. 40 GHz (gigahertz) band, operating (in the United States) under Part 15 of the FCC Rules and Regulations. Because of this choice of frequency band, 802. 11b and 802. 11g equipment can incur interference from microwave ovens, cordless telephones, Bluetooth devices, and other appliances using this same band. The 802. 1a standard uses the 5 GHz band, and is therefore not affected by products operating on the 2. 4 GHz band. Table 1. 1: Protocol Summary of IEEE 802. 11 Protocol Legacy 802. 11a 802. 11b 802. 11g 802. 11n Release Date 1997 1999 1999 2003 2006 Operating Frequency GHz 2. 4-2. 5 5 2. 4-2. 5 2. 4-2. 5 2. 4 and/or 5 Throughput (Typ) Mbps 0. 7 23 4 19 74 Data Rate (Max) Mbps 2 54 11 54 248 = 2Ãâ€" 2 ant Range (Indoor) meters ~25 ~30 ~35 ~35 ~70 Range (Outdoor) meters ~75 ~100 ~110 ~115 ~160 2 1. 2 Why it should be used? Bangladesh entered the Internet world in 1993 using offline E-mail services. Online Dial-up services started in 1996 through VSAT based data connectivity. But it is not possible to give a Dial-up connection to all because; it uses the BTTB’s telephone line. While Dial-up is active the phone line is busy and it is not possible to give a client more than 4/5 Kbps speed. Using an ADSL modem it can be increased to more than 2 Mbps. But it is not enough for a corporate user and also it is very costly and there are many other problems which has described below. The Ethernet connectivity can give a maximum of 100 Mbps. But its range is too small. Wireless LAN has vast benefits over wired network in some aspects. In our country especially in big cities like Dhaka, it is very hard job to establish a wired network all over the city. Because, it is over populated, buildings were made with out any proper plan and also the roads. Generally the wire lines are established over head, which is not so secured. Wire can be broken due to any kind of natural or man made problem. It may be theft. Or it can be misused by any one by taking a parallel line from it. It may create leak of data security. It is also very expensive to establish a copper wire network road by road and maintenance of it. Besides that there are many rivers, cannels in our county, and also hill tracks in some parts. It is not possible to give a wired network over those. For all those reasons it is not a wise decision to use a wired network in our country. A Wireless LAN can be more reliable, low cost, convenient network considering above aspects. There are a number of Internet Service Provider (ISP) companies in our country giving Wireless LAN support to the clients. Those are known as Wireless ISP. These ISPs give internet or intranet service to the clients as their requirements. Those networks are reliable and also secured. It is easy to establish a connection in the company’s coverage area using a wireless device at the client end. The Wireless ISP Company should have proper resources to give that coverage. A model of a Wireless ISP company’s wireless part for Bangladesh is given below. The nation wide link can be a optical fiber or microwave link. Here the main coverage is shown in Dhaka city and thus BSSs are shown at here is more than one. It can be expand the network in other areas by adding additional equipments required to establish a BSS. And also it can give coverage on other areas by establish same network on that area. Figure 1. 1: Model of a Wireless ISP 1. 3 Why one should be interested in WLAN field? The telecom industry is changing with breathtaking speed. There are a lot of telecommunication and Wireless ISP companies working in our country and there are a lot of companies to come. At present telecommunication is the most challenging and interesting field out of all other e ngineering fields. All the telecom company has some common structure. So, there are many similarities between a mobile or PSTN (Public Switched Telephone Network) operator and a Wireless ISP. The skills one gather from a Wireless ISP can use in the telecom companies. The man can be skilled on installing different devices, surveying a site, proposing a link budget. He can face the practical problems occur in installing radio networks and can be skilled in solving those problems and also troubleshoot the devices and the radio link. In the mobile operators, there are many restrictions. One can not work with all things. But as still Wireless ISP companies are smaller in our country one can get opportunity to work in different sections which will increase his experiences and skills. Lastly it can be say that, as it is a challenging field, the person likes facing challenges will enjoy working in this field 4 1. 4 Organization of this report This Internship report has seven chapters in total. The second chapter contains theory about the radio frequency properties and different modulation techniques In third chapter, different RF antennas and it accessories are described. Fourth chapter contains the Wireless LAN’s theory and architecture in brief. Chapter five analyzes to survey a site, and how to budget a link. The sixth chapter describes the device installation process for the APERTO and CANOPY devices. The seventh and final chapter is the concluding chapter where limitations of this works are reported and few suggestions of our work are provided along with the concluding remarks. 1. 5 Aims and objectives 5 RF Properties and Modulation Techniques CHAPTER 2 6 Chapter 2 RF Properties and Modulation Techniques 2. 1 Radio Frequency 2. 2. 1 Radio Frequency Radio frequencies are high frequency alternating current (AC) signals that are passed along a copper conductor and then radiated into the air via an antenna. An antenna converts/transforms a wired signal to a wireless signal and vice versa. When the high frequency AC signal is radiated into the air, it forms radio waves. These radio waves propagate (move) away from the source (the antenna) in a straight line in all directions at once. 2. 2. 2 RF Behaviors RF is sometimes referred to as â€Å"smoke and mirrors† because RF seems to act erratically and inconsistently under given circumstances. Things as small as a connector not being tight enough or a slight impedance mismatch on the line can cause erratic behavior and undesirable results. The following sections describe these types of behaviors and what can happen to radio waves as they are transmitted. Gain Gain, illustrated in Figure 2. 1, is the term used to describe an increase in an RF signal' amplitude [2]. Gain is usually an active process; meaning that an external s power source, such as an RF amplifier, is used to amplify the signal or a high-gain antenna is used to focus the beam width of a signal to increase its signal amplitude. Figure 2. 1: Power gain However, passive processes can also cause gain. For example, reflected RF signals combine with the main signal to increase the main signal' strength. Increasing the RF s signal' strength may have a positive or a negative result. Typically, more power is s better, but there are cases, such as when a transmitter is radiating power very close to legal power output limit, where added power would be a serious problem. 7 Loss Loss describes a decrease in signal strength (Figure 2. 2). Many things can cause RF signal loss, both while the signal is still in the cable as a high frequency AC electrical signal and when the signal is propagated as radio waves through the air by the antenna. Resistance of cables and connectors causes loss due to the converting of the AC signal to heat. Impedance mismatches in the cables and connectors can cause power to be reflected back toward the source, which can cause signal degradation. Objects directly in the propagated wave' transmission path can absorb, reflect, or s destroy RF signals. Loss can be intentionally injected into a circuit with an RF attenuator. RF attenuators are accurate resistors that convert high frequency AC to heat in order to reduce signal amplitude at that point in the circuit. [2] Figure 2. 2: Power loss Being able to measure and compensate for loss in an RF connection or circuit is important because radios have a receive sensitivity threshold. A sensitivity threshold defined as the point at which a radio can clearly distinguish a signal from background noise. Since a receiver’s sensitivity is finite, the transmitting station must transmit signal with enough amplitude to be recognizable at the receiver. If losses occur between the transmitter and receiver, the problem must be corrected either by removing the objects causing loss or by increasing the transmission power. Reflection Reflection, (as illustrated in Figure 2. 3) occurs when a propagating electromagnetic wave impinges upon an object that has very large dimensions when compared to the wavelength of the propagating wave [3]. Reflections occur from the surface of the earth, buildings, walls, and many other obstacles. If the surface is smooth, the reflected signal may remain intact, though there is some loss due to absorption and scattering of the signal. Figure 2. 3: Reflection 8 RF signal reflection can cause serious problems for wireless LANs. This reflecting main signal from many objects in the area of the transmission is referred to as multipath. Multipath can have severe adverse affects on a wireless LAN, such as degrading or canceling the main signal and causing oles or gaps in the RF coverage area. Surfaces such as lakes, metal roofs, metal blinds, metal doors, and others can cause severe reflection, and hence, multipath. Reflection of this magnitude is never desirable and typically requires special functionality (antenna diversity) within the wireless LAN hardware to compensate for it. Refraction Refraction describes the bending of a radio wave as it passes through a medium of different density. A s an RF wave passes into a denser medium (like a pool of cold air lying in a valley) the wave will be bent such that its direction changes. When passing through such a medium, some of the wave will be reflected away from the intended signal path, and some will be bent through the medium in another direction, as illustrated in Figure 2. 4. [3] Figure 2. 4: Refraction Refraction can become a problem for long distance RF links. As atmospheric conditions change, the RF waves may change direction, diverting the signal away from the intended Diffraction Diffraction occurs when the radio path between the transmitter and receiver is obstructed by a surface that has sharp irregularities or an otherwise rough surface [3]. At high frequencies, diffraction, like reflection, depends on the geometry of the obstructing object and the amplitude, phase, and polarization of the incident wave at the point of diffraction. Diffraction is commonly confused with and improperly used interchangeably with refraction. Care should be taken not to confuse these terms. Diffraction describes a wave bending around an obstacle (Figure 2. 5), whereas refraction describes a wave bending through a medium. Taking the rock in the pond example from above, now consider a small twig sticking up through the surface of the water near where the rock. As the ripples hit the stick, they would be blocked to a small degree, but to a larger degree, the ripples would bend around the twig. This illustration shows how diffraction acts with obstacles in its path, depending on the makeup of the obstacle. If Object was large or jagged enough, the wave might not bend, but rather might be blocked. 9 Figure 2. 5: Diffraction Diffraction is the slowing of the wave front at the point where the wave front strikes an obstacle, while the rest of the wave front maintains the same speed of propagation. Diffraction is the effect of waves turning, or bending, around the obstacle. As another example, consider a machine blowing a steady stream of smoke. The smoke would flow straight until an obstacle entered its path. Introducing a large wooden block into the smoke stream would cause the smoke to curl around the corners of the block causing a noticeable degradation in the smoke' velocity at that point and a significant s change in direction. Scattering Scattering occurs when the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength of the signal, and the number of obstacles per unit volume is large [3]. Scattered waves are produced by rough surfaces, small objects, or by other irregularities in the signal path, as can be seen in Figure 2. 6. Figure 2. 6: Scattering Some outdoor examples of objects that can cause scattering in a mobile communications system include foliage, street signs, and lampposts. Scattering can take place in two primary ways. First, scattering can occur when a wave strikes an uneven surface and is reflected in many directions simultaneously. Scattering of this type yields many small amplitude reflections and destroys the main RF signal. Dissipation of an RF signal may occur when an RF wave is reflected off sand, rocks, or other jagged surfaces. When scattered in this manner, RF signal degradation can be significant to the point of intermittently disrupting communications or causing complete signal loss. 10 Second, scattering can occur as a signal wave travels through particles in the medium such as heavy dust content. In this case, rather than being reflected off an uneven surface, the RF waves are individually reflected on a very small scale off tiny particles. Voltage Standing Wave Ratio (VSWR) VSWR occurs when there is mismatched impedance (resistance to current flow, measured in Ohms) between devices in an RF system. VSWR is caused by an RF signal reflected at a point of impedance mismatch in the signal path. VSWR causes return loss which is defined as the loss of forward energy through a system due to some of the power being reflected back towards the transmitter. If the impedances of the ends of a connection do not match, then the maximum amount of the transmitted power will not be received at the antenna. When part of the RF signal is reflected back toward the transmitter, the signal level on the line varies instead of being steady. This variance is an indicator of VSWR. [2] As an illustration of VSWR, imagine water flowing through two garden hoses. As long as the two hoses are the same diameter, water flows through them seamlessly. If the hose connected to the faucet were significantly larger than the next hose down the line, there would be backpressure on the faucet and even at the connection between the two hoses. This standing backpressure illustrates VSWR, as can be seen in Figure 2. . In this example, you can see that backpressure can have negative effects and not nearly as much water is transferred to the second hose as there would have been with matching hoses screwed together properly. Figure 2. 7: VSWR-like water through a hose VSWR Measurements VSWR is a ratio, so it is expressed as a relationship between two numbers. A typical VSWR value would be 1. 5:1. The two numbers re late the ratio of impedance mismatch against a perfect impedance match. The second number is always 1, representing the perfect match, where as the first number varies. The lower the first number (closer to 1), the better impedance matching your system has. For example, a VSWR of 1. 1:1 is better than 1. 4:1. A VSWR measurement of 1:1 would denote a perfect impedance match and no voltage standing wave would be present in the signal path. Effects of VSWR Excessive VSWR can cause serious problems in an RF circuit. Most of the time, the result is a marked decrease in the amplitude of the transmitted RF signal. However, 11 since some transmitters are not protected against power being applied (or returned) to the transmitter output circuit, the reflected power can burn ut the electronics of the transmitter. VSWR' effects are evident when transmitter circuits burn out, power s output levels are unstable, and the power observed is significantly different from the expected power. The methods of changing VSWR in a circuit include proper use of proper equipment. Tight connections between cables and connectors, use of impedance matched hardware throughout, and use of high-quality equipment with calibration reports where necessary are all good preventative measures against VSWR. VSWR can be measured with high-accuracy instrumentation such as SWR meters, but this measurement is beyond the scope of this text and the job tasks of a network administrator. 2. 2 Spread Spectrum 2. 2. 1 Spread Spectrum Spread spectrum is a communications technique characterized by wide bandwidth and low peak power. Spread spectrum communication uses various modulation techniques in wireless LANs and possesses many advantages over its precursor, narrow band communication [4]. Spread spectrum signals are noise-like, hard to detect, and even harder to intercept or demodulate without the proper equipment. Jamming and interference have a lesser affect on a spread spectrum communication than on narrow band communications. For these reasons, spread spectrum has long been a favorite of the military. 2. 2. 2 Narrow Band Transmission A narrowband transmission is a communications technology that uses only enough of the frequency spectrum to carry the data signal and no more, spread spectrum is in opposition to that mission since it uses much wider frequency bands than is necessary to transmit the information. This brings us to the first requirement for a signal to be considered spread spectrum. A signal is a spread spectrum signal when the bandwidth is much wider than what is required to send the information. [4] Figure 2. 8 illustrates the difference between narrowband and spread spectrum transmissions. One of the characteristics of narrow band is high peak power. More power is required to send a transmission when using a smaller frequency range. In order for narrow band signals to be received, they must stand out above the general level of noise, called the noise floor, by a significant amount. Because its band is so narrow, and high peak power ensures error-free reception of a narrow band signal. 12 Figure 2. 8: Narrow band verses Spread Spectrum on a frequency domain A compelling argument against narrowband transmission-other than the high peak power required to send it-is that narrow band signals can be jammed or experience interference very easily. Jamming is the intentional overpowering of a transmission using unwanted signals transmitted on the same band. Because its band is so narrow, other narrow band signals, including noise, can completely eliminate the information by overpowering a narrowband transmission; much like a passing train overpowers a quiet conversation. 2. 2. 3 Spread Spectrum Technology Spread spectrum technology allows taking the same amount of information than previously using a narrow band carrier signal and spreading it out over a much larger frequency range. For example, 1 MHz at 10 Watts with narrow band, but 20 MHz at 100 mW with spread spectrum. By using a wider frequency spectrum, we reduce the probability that the data will be corrupted or jammed. A narrow band jamming attempt on a spread spectrum signal would likely be thwarted by virtue of only a small part of the information falling into the narrow band signal' frequency range. s s Most of the digital data would be received error-free [4]. Today' spread spectrum RF radios can retransmit any small amount of data loss due to narrowband interference. While the spread spectrum band is relatively wide, the peak power of the signal is quite low. This is the second requirement for a signal to be considered spread spectrum. For a signal to be considered spread spectrum, it must use low power. These two characteristics of spread spectrum (use of a wide band of frequencies and very low power) make it look to most receivers as if it were a noise signal. Noise is a wide band, low power signal, but the difference is that noise is unwanted. Furthermore, since most radio receivers will view the spread spectrum signal as noise, these receivers will not attempt to demodulate or interpret it, creating a slightly more secure communication. 2. 2. 4 Frequency Hopping Spread Spectrum (FHSS) Frequency hopping spread spectrum is a spread spectrum technique that uses frequency agility to spread the data over more than 83 MHz. Frequency agility refers to the radio’s ability to change transmission frequency abruptly within the usable RF frequency band [4]. In the case of frequency hopping wireless LANs, the usable portion of the 2. GHz ISM band is 83. 5 MHz, per FCC regulation and the IEEE 802. 11 standard. 13 How FHSS Works In frequency hopping systems, the carrier changes frequency, or hops, according to a pseudorandom sequence. The pseudorandom sequence is a list of several frequencies to which the carrier will hop at specified time intervals before repeating the pattern. The transmitter uses this hop sequence to select it s transmission frequencies. The carrier will remain at a certain frequency for a specified time (known as the dwell time), and then use a small amount of time to hop to the next frequency (hop time). When the list of frequencies has been exhausted, the transmitter will repeat the sequence. Figure 2. 9 shows a frequency hopping system using a hop sequence of five frequencies over 5 MHz band. In this example, the sequence is: 1. 2. 449 GHz 2. 2. 452 GHz 3. 2. 448 GHz 4. 2. 450 GHz 5. 2. 451 GHz Figure 2. 9: Single frequency hopping system Once the radio has transmitted the information on the 2. 451 GHz carrier, the radio will repeat the hop sequence, starting again at 2. 449 GHz. The process of repeating the sequence will continue until the information is received completely. The receiver radio is synchronized to the transmitting radio' hop sequence in order to s receive on the proper frequency at the proper time. The signal is then demodulated and used by the receiving computer. Effects of Narrow Band Interference Frequency hopping is a method of sending data where the transmission and receiving systems hop along a repeatable pattern of frequencies together. As is the case with all spread spectrum technologies, frequency hopping systems are resistant-but not immune-to narrow band interference. In example in Figure 2. 9, if a signal were to interfere with our frequency hopping signal on, say, 2. 51 GHz, only that portion of the spread spectrum signal would be lost. The rest of the spread spectrum signal would remain intact, and the lost data would be retransmitted. 14 In reality, an interfering narrow band signal may occupy several megahertz of bandwidth. Since a frequency hopping band is over 83 MHz wide, even this interfering signal will cause little de gradation of the spread spectrum signal. Frequency Hopping Systems The IEEE and Open-Air standards regarding FHSS systems describe: 1. The frequency bands which may be used 2. Hop sequences 3. Dwell times 4. Data rates The IEEE 802. 1 standard specifies data rates of 1 Mbps and 2 Mbps and Open-Air (a standard created by the now defunct Wireless LAN Interoperability Forum) specifies data rates of 800 kbps and 1. 6 Mbps. In order for a frequency hopping system to be 802. 11 or Open-Air compliant, it must operate in the 2. 4 GHz ISM band (which is defined by the FCC as being from 2. 4000 GHz to 2. 5000 GHz). Both standards allow operation in the range of 2. 4000 GHz to 2. 4835 GHz. Channels A frequency hopping system will operate using a specified hop pattern called a channel. Frequency hopping systems typically use the FCC’s 26 standard hop patterns or a subset thereof. Some frequency hopping systems will allow custom hop patterns to be created, and others even allow synchronization between systems to completely eliminate collisions in a co-located environment. Figure 2. 10: Co-located frequency hopping system Though it is possible to have as many as 79 synchronized, co-located access points, with this many systems, each frequency hopping radio would require precise synchronization with all of the others in order not to interfere with (transmit on the same frequency as) another frequency hopping radio in the area. The cost of such a set of systems is prohibitive and is generally not considered an option. If synchronized radios are used, the expense tends to dictate 12 co-located systems as the maximum. 15 If non-synchronized radios are to be used, then 26 systems can be co-located in a wireless LAN; this number is considered to be the maximum in a medium-traffic wireless LAN. Increasing the traffic significantly or routinely transferring large files places the practical limit on the number of co-located systems at about 15. More than 15 co-located frequency-hopping systems in this environment will interfere to the extent that collisions will begin to reduce the aggregate throughput of the wireless LAN. Dwell Time In frequency hopping systems, it must transmit on a specified frequency for a time, and then hop to a different frequency to continue transmitting. When a frequency hopping system transmits on a frequency, it must do so for a specified amount of time. This time is called the dwell time. Once the dwell time has expired, the system will switch to a different frequency and begin to transmit again. Suppose a frequency hopping system transmits on only two frequencies, 2. 401 GHz and 2. 402 GHz. The system will transmit on the 2. 01 GHz frequency for the duration of the dwell time100 milliseconds (ms), for example. After 100ms the radio must change its transmitter frequency to 2. 402 GHz and send information at that frequency for 100ms. Hop Time When considering the hopping action of a frequency hopping radio, dwell time is only part of the story. When a frequency hopping radio jumps from frequency A to frequency B, it must change the transmit frequency in one of two ways. It ei ther must switch to a different circuit tuned to the new frequency, or it must change some element of the current circuit in order to tune to the new frequency. In either case, the process of changing to the new frequency must be complete before transmission can resume, and this change takes time due to electrical latencies inherent in the circuitry. There is a small amount of time during this frequency change in which the radio is not transmitting called the hop time. The hop time is measured in microseconds ( µs) and with relatively long dwell times of around 100-200 ms, the hop time is not significant. A typical 802. 11 FHSS system hops between channels in 200-300  µs. With very short dwell times of 500 – 600 µs, like those being used in some frequency hopping systems such as Bluetooth, hop ime can become very significant. If we look at the effect of hop time in terms of data throughput, we discover that the longer the hop time in relation to the dwell time, the slower the data rate of bits being transmitted. 2. 2. 5 Direct Sequence Spread Spectrum (DSSS) Direct sequence spread spectrum is very widely known and the most used of the spread spectrum types, owing most of its popularity to its ease of implementation and high data rates. The majority of wireless LAN equipment on the market today uses DSSS technology. DSSS is a method of sending data in which the transmitting and receiving systems are both on a 22 MHz-wide set of frequencies. The wide channel enables devices to transmit more information at a higher data rate than current FHSS systems. 16 How DSSS Works DSSS combines a data signal at the sending station with a higher data rate bit sequence, which is referred to as a chipping code or processing gain. A high processing gain increases the signal’s resistance to interference. The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20. The IEEE 802. 11 working group has set their minimum processing gain requirements at 11. The process of direct sequence begins with a carrier being modulated with a code sequence. The number of–chips-in the code will determine how much spreading occurs, and the number of chips per bit and the speed of the code (in chips per second) will determine the data rate. Direct Sequence Spread Spectrum (DSSS) Direct sequence spread spectrum is very widely known and the most used of the spread spectrum types, owing most of its popularity to its ease of implementation and high data rates. The majority of wireless LAN equipment on the market today uses DSSS technology. DSSS is a method of sending data in which the transmitting and receiving systems are both on a 22 MHz-wide set of frequencies. The wide channel enables devices to transmit more information at a higher data rate than current FHSS systems. How DSSS Works DSSS combines a data signal at the sending station with a higher data rate bit sequence, which is referred to as a chipping code or processing gain. A high processing gain increases the signal’s resistance to interference. The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20. The IEEE 802. 11 working group has set their minimum processing gain requirements at 11. The process of direct sequence begins with a carrier being modulated with a code sequence. The number of-chips-in the code will determine how much spreading occurs, and the number of chips per bit and the speed of the code (in chips per second) will determine the data rate. Channels Unlike frequency hopping systems that use hop sequences to define the channels, direct sequence systems use a more conventional definition of channels. Each channel is a contiguous band of frequencies 22 MHz wide and 1 MHz carrier frequencies are used just as with FHSS. Channel 1, for instance, operates from 2. 401 GHz to 2. 423 GHz (2. 412 GHz  ± 11 MHz); channel 2 operates from 2. 406 to 2. 429 GHz (2. 417  ± 11 MHz), and so forth. Figure 2. 11 illustrates this point. 17 Figure 2. 11: channel allocation and Spectral relationship The chart in Table 2. 1 has a complete list of channels used in the United States and Europe. The FCC specifies only 11 channels for non-licensed use in the United States. Each of the frequencies listed in this chart are considered center frequencies. From this center frequency, 11 MHz is added and subtracted to get the useable 22 MHz wide channel. Easy to see that adjacent channels (channels directly next to each other) would overlap significantly. Table 2. 1: DSSS channel frequency Assignment Channel ID 1 2 3 4 5 6 7 8 9 10 11 FCC Channel Frequencies GHz 2. 412 2. 417 2. 422 2. 427 2. 432 2. 437 2. 442 2. 447 2. 452 2. 457 2. 462 ETSI Channel Frequencies GHz N/A N/A 2. 422 2. 427 2. 432 2. 437 2. 442 2. 447 2. 452 2. 457 2. 462 To use DSSS systems with overlapping channels in the same physical space would cause interference between the systems. DSSS systems with overlapping channels should not be co-located because there will almost always be a drastic or complete reduction in throughput. Because the center frequencies are 5 MHz apart and the channels are 22 MHz wide, channels should be co-located only if the channel numbers are at least five apart: channels 1 and 6 do not overlap, channels 2 and 7 do not overlap, etc. There is a maximum of three co-located direct sequence systems possible because channels 1, 6 and 11 are the only theoretically non-overlapping channels. The 3 non-overlapping channels are illustrated in Figure 2. 2 18 Figure 2. 12: DSSS non-overlapping Channel 2. 2. 6 Comparing FHSS and DSSS Both FHSS and DSSS technologies have their advantages and disadvantages, and it incumbent on the wireless LAN administrator to give each its due weight when deciding how to implement a wireless LAN [4]. This section will cover some of the factors that should be discussed when determining which technology is appropriate f or your organization, including: 1. Narrowband interference 2. Co-location 3. Cost 4. Equipment compatibility 5. Data rate and throughput 6. Security 7. Standards support Narrowband Interference The advantages of FHSS include a greater resistance to narrow band interference. DSSS systems may be affected by narrow band interference more than FHSS because of the use of 22 MHz wide contiguous bands instead of the 79 MHz used by FHSS. This fact may be a serious consideration if the proposed wireless LAN site is in an environment that has such interference present. Co-location An advantage of FHSS over DSSS is the ability for many more frequency hopping systems to be co-located than direct sequence systems. Since frequency hopping systems are-frequency agile-and make use of 79 discrete channels, frequency hopping systems have a co-location advantage over direct sequence systems, which have a maximum co- location of 3 access points. 19 Figure 2. 13: Co-location Comparison However, when calculating the hardware costs of an FHSS system to get the same throughput as a DSSS system, the advantage quickly disappears. Because DSSS can have 3 co-located access points, the maximum throughput for this configuration would be: 3 access points ? 1 Mbps = 33 Mbps At roughly 50% of rated bandwidth, the DSSS system throughput would be approximately: 33 Mbps / 2 = 16. 5 Mbps To achieve roughly the same rated system bandwidth using an IEEE 802. 11 compliant FHSS system would require: 16 access points ? 2 Mbps = 32 Mbps At roughly 50% of rated bandwidth, the FHSS system throughput would be approximately: 32 Mbps / 2 = 16 Mbps In this configuration, an FHSS system would require 13 additional access points t o be purchased to get the same throughput as the DSSS system. Also, additional installation services for these units, cables, connectors, and antennas would all need to be purchased. Cost: When implementing a wireless LAN, the advantages of DSSS may be more compelling than those of FHSS systems, particularly when driven by a tight budget. The cost of implementing a direct sequence system is far less than that of a frequency hopping system. DSSS equipment is widely available in today’s marketplace, and its rapid adoption has helped in driving down the cost. Only a few short years ago, equipment was only affordable by enterprise customers. Today, very good quality 802. 11b compliant PC cards can be purchased for under $100. FHSS cards complying with either the 802. 11 or Open-Air standards typically run between $150 and $350 in today' market depending on the manufacturer and the standards to which the cards s adhere. 20 Equipment compatibility and availability The Wireless Ethernet Compatibility Alliance (WECA) provides testing of 802. 11b compliant DSSS wireless LAN equipment to ensure that such equipment will operate in the presence of and interoperate with other 802. 11b DSSS devices. The interoperability standard that WECA created and now uses is called Wireless Fidelity, or Wi-Fi, and hose devices that pass the tests for interoperability are-Wi-Fi compliant-devices. Devices so deemed are allowed to affix the Wi-Fi logo on the related marketing material and devices themselves showing that they have been tested and interoperate with other Wi-Fi compliant devices. There are no such compatibility tests for equipment that uses FHSS. There are standards such as 802. 11 and Open-Air, but no organization h as stepped forward to do the same kind of compatibility testing for FHSS as WECA does for DSSS. Due to the immense popularity of 802. 11b compliant radios, it is much easier to obtain these units. The demand seems only to be growing for the Wi-Fi compliant radios while the demand for FHSS radios has remained fairly steady, even decreasing to some degree over the past year. Data rate and throughput The latest frequency hopping systems are slower than the latest DSSS systems mostly because their data rate is only 2 Mbps. Though some FHSS systems operate at 3 Mbps or more, these systems are not 802. 11 compliant and may not interoperate with other FHSS systems. FHSS and DSSS systems have a throughput (data actually sent) of only about half of the data rate. When testing the throughput of a new wireless LAN installation, achieving 5-6 Mbps on the 11 Mbps setting for DSSS or 1 Mbps on the 2 Mbps setting common using DSSS. When wireless frames are transmitted, there are pauses between data frames for control signals and other overhead tasks. With frequency hopping systems, this interframe spacing is longer than that used by direct sequence systems, causing a slow-down in rate that data is actually sent (throughput). Additionally, when the frequency hopping system is in the process of changing the transmit frequency, no data is sent. This translates to more lost throughput, albeit only a minor amount. Some wireless LAN systems use proprietary physical layer protocols in order to increase throughput. These methods work, yielding throughputs as high as 80% of the data rate, but in so doing, sacrifice interoperability. Security: It is widely touted-and is a myth-that frequency hopping systems are inherently more secure than direct sequence systems. The first fact that disproves this myth is that FHSS radios are only produced by a minimal number of manufacturers. Of this small list of manufacturers, all of them adhere to standards such as 802. 1 or Open-Air in order to sell their products effectively. Second, each of these manufacturers uses a standard set of hop sequences, which generally comply with a pre-determined list, produced by the standards body (IEEE or WLIF). These 2 items together make breaking the code of hop sequences relatively simple. 21 Other reasons that make finding the hop sequence quite simple is that the channel number is broadcasted in the clear with each beacon. Also, the MAC address of the transmitting access point can be seen with each beacon (which indicates the manufacturer of the radio). Some manufacturers allow the administrator the flexibility of defining custom hopping patterns. However, even this custom capability is no level of security since fairly unsophisticated devices such as spectrum analyzers and a standard laptop computer can be used to track the hopping pattern of a FHSS radio in a matter of seconds. Standards Support: DSSS has gained wide acceptance due to low cost, high speed, WECA' Wi-Fi s interoperability standards, and many other factors. This market acceptance will only accelerate due to the industry moving toward newer, faster DSSS systems such as the new 802. 1g and 802. 11a compliant wireless LAN hardware. WECA' new Wi-Fi5 s interoperability standard for 5 GHz DSSS systems operating in the UNII bands will help move the industry along even faster in the same direction it is already headed. The new standards for FHSS systems include Home RF 2. 0 and 802. 15 (in support of WPANs such as Bluetooth), but none for advancing FHSS systems in the enterp rise. 2. 2. 7 BPSK In BPSK, the phase of the carrier is varied to represent binary 1 or 0 . Both peak amplitude and frequencies remain constant as the phase changes. For example, if a phase of 0 represents binary 0, then the phase 180 represents binary 1. the phase of the signal during each bit duration is constant. And its value depends on the bit (0 or 1). Figure 2. 14 shows a conceptual view of BPSK. BPSK is also known as 2-PSK. because two different phases (0 and 180) are used. The table below shows BPSK which makes the relationship of phase to bit value. Bit 0 1 Phase 0? 180? Figure 2. 14: BPSK. 2. 2. 8 QPSK The diagram for the signal is given in Figure 2. 15. A phase of 0 now represents 00; 90 represents 01; 180 represents10; and 270 represents 11. This technique is called QPSK. The pair of bits represented by each phase is called a dibit. 22 Bit 00 01 10 11 Figure 2. 15: QPSK. Phase 0? 90? 180? 270? 2. 2. 9 QAM QAM is a Combination of ASK and PSK so that a maximum contrast between each signal unit (bit, dibit, tribit, and so on) is achieved. QAM takes the advantages of the fact that it is possible to send two different signals simultaneously on the same carrier frequency . by using two copies of the carrier frequency. One shifted by 90 with respect to the other. For QAM, each carrier is ASK modulated. The two independent signals are simultaneously transmitted over the same medium. In QAM the number of amplitude shifts is fewer than the number of phase shifts. Because amplitude changes are susceptible to noise and require greater shift distances than do phase changes, the number of phase shifts used by a QAM system is always larger than the number of amplitude shifts. [5] Figure 2. 16: QAM. 23 2. 2. 10 Orthogonal Frequency division Multiplexing (OFDM) Orthogonal Frequency division Multiplexing offers the highest data rates and maximum resistance to interference and corruption of all the signal manipulation techniques in use in 802. 1 today [5]. Although it is not considered a spread spectrum technique by the FCC, OFDM shares many qualities with spread spectrum communicators, including using a low transmit power and wider-than-necessary bandwidth. OFDM is used to provide data rates up to 54 Mbps in 802. 11a and 802. 11g. How OFDM Works OFDM achieves high data rates by squeezing a large number of Communication Channels into a given frequency band. Normally, two c ommunication channels must be separated by a certain amount of bandwidth or they overlap and interfere. Specially, each Channel has harmonics that extend up and down the frequency space, decreasing in amplitude as they get farther from the channels fundamental signal. Even if two channels are non-overlapping, their harmonics may overlap and the signal can be corrupted. An OFDM communicator can place adjacent communication channels very precisely in the frequency space in such a way that the channels harmonics exactly cancel each other, effectively leaving only the fundamental signals. OFDM achieves high data rates by dividing a single communication channel into a large number of closely-spaced, small bandwidth sub-carriers. Each sub-carrier individually has a relatively low data rate, but by transmitting data in parallel on all sub-carriers simultaneously, high data rates can be achieved. Figure 2. 17: OFDM frequency plot. Figure 2. 17 shows an example of a frequency spectrum for an OFDM transmitter. Each of the peaks represents a single sub-carrier, and the sub-carriers together make up the communications channel. The sub-carriers are precisely aligned so that the zero-points of their harmonics overlapped exactly. The majority of the harmonic energy will cancel out, leaving just the sub-carriers. 4 CHAPTER 3 RF Antenna and Accessories 25 Chapter 3 RF Antenna and Accessories 3. 1 Introduction Antennas are most often used to increase the range of wireless LAN systems, but proper antenna selection can also enhance the security of your wireless LAN. A properly chosen and positioned antenna can reduce the signal leaking out of workspace, and make signal interception extremely difficult. 3. 2 RF Antennas An RF antenna is a device used to convert high frequency (RF) signals on a transmission line (a cable or waveguide) into propagated waves in the air [6]. The electrical fields emitted from antennas are called beams or lobes. Antenna convert electrical energy into RF waves in the case of a transmitting antenna, or RF waves into electrical energy in the case of a receiving antenna. The physical dimensions of an antenna, such as its length, are directly related to the frequency at which the antenna can propagate waves or receive propagated waves. The physical structure of an antenna is directly related to the Shape of the area in which it concentrates most of its related RF energy. There are three generic categories of RF antennas: 1. Omni-directional 2. Semi-directional 3. Highly-directional Each category has multiple types of antennas, each having different RF characteristics and appropriate uses. As the gain of an antenna goes up, the coverage area narrows so that high-gain antennas offer longer coverage areas than low-gain antennas at the same input power level. 3. 2. 1 Omni-directional (Dipole) Antennas The dipole is an omni- directional antenna, because it radiates its energy equally in all directions around its axis. Dipole antenna is Simple to design; dipole antenna is standard equipment on most access points. Directional antennas concentrate their energy into a cone, known as a â€Å"beam. † Figure 3. 1: Dipole doughnut 26 Figure 3. 1 shows that the dipole' radiant energy is concentrated into a region that s looks like a doughnut, with the dipole vertically through the â€Å"hole† of the â€Å"doughnut. † The signal from an omni-directional antenna radiates in a 360-degree horizontal beam. If an antenna radiates in all directions equally (forming a sphere), it is called an isotropic radiator, which is the theoretical reference for antennas, but rather, practical antennas all have some type of gain over that of an isotropic radiator. The dipole radiates equally in all directions around its axis, but does not radiate along the length of the wire itself – hence the doughnut pattern. The side view of a dipole radiator as it radiates waves in Figure 3. 2. Figure 3. 2: Dipole-side view If a dipole antenna is placed in the center of a single floor of a multistory building, most of its energy will be radiated along the length of that floor, with some significant fraction sent to the floors above and below the access point. Figure 3. 3 shows examples of some different types of omni-directional antennas. Figure 3. 3: Sample omni-directional antenna Figure 3. 4 shows a two-dimensional example of the top view and side view of a dipole antenna. Figure 3. 4: Coverage area of an omni-directional antenna High-gain omni-directional antennas offer more horizontal coverage area, but the vertical coverage area is reduced, as can be seen in Figure 3. 5. 27 Figure 3. 5: Coverage area of high gain omni-directional antennas This characteristic can be an important consideration when mounting a high-gain omni antenna indoors on the ceiling. If the ceiling is too high; the coverage area may not reach the floor, where the users are located. Usages Omni-directional antennas are used when coverage in all directions around the horizontal axis of the antenna is required. Omni-directional antennas are most effective where large coverage areas are needed around a central point. For example, placing an omni- directional antenna in the middle of a large, open room would provide good coverage. Omni-directional antennas are commonly used for point-tomultipoint designs with a hub-n-spoke topology. Used outdoors, an omni-directional antenna should be placed on top of a structure (such as a building) in the middle of the Figure 3. 6: Point to multipoint link coverage area. For example, on a college campus the antenna might be placed in the center of the campus for the greatest coverage area. When used indoors, the antenna should be placed at the middle of the building or desired coverage area, near the ceiling, for optimum coverage. Omni-directional antennas emit a large coverage area in a circular pattern and are suitable for warehouses or tradeshows where coverage is usually from one corner of the building to the other. 3. 2. 2 Semi directional Antenna Semi directional antennas direct the energy from the transmitter significantly more in one particular direction rather than the uniform circular pattern that is common with the omni- directional antenna; Semi-directional antennas come in many different styles and shapes. Some semi- directional antennas types frequently used with wireless LANs are Patch, Panel, and Yagi (pronounced â€Å"YAH-gee†) antennas. All of these antennas are generally flat and designed for wall mounting. Each type has different coverage characteristics. Figure 3. shows some examples of semidirectional antennas. 28 Figure 3. 7: Sample semi-directional antenna Semi-directional antennas often radiate in a hemispherical or cylindrical coverage pattern as can be seen in Figure 3. 8. Figure 3. 8: Coverage area of a semi-directional antenna Usages Semi-directional antennas are ideally suited for short and medium range bridging. For example, two office buildings that are across the street from one another and n eed to share a network connection would be a good scenario in which to implement semidirectional antennas. In a large indoor space, if the transmitter must be located in the corner or at the end of a building, a corridor, or a large room, a semi-directional antenna would be a good choice to provide the proper coverage. Figure 3. 9 illustrates a link between two buildings using semi-directional antennas. Figure 3. 9: Point to point link using semi-directional antenna In some cases, semi-directional antennas provide such long-range coverage that they may eliminate the need for multiple access points in a building. For example, in a long hallway, several access points with omni antennas may be used or perhaps only one or two access points with properly placed semi-directional antennas – saving the customer a significant amount of money. In some cases, semi- directional antennas have back and side lobes that, if used effectively, may further reduce the need for additional access points. 29 3. 2. 3 Highly directional antenna Highly-directional antennas emit the most narrow signal beam of any antenna type and have the greatest gain of these three groups of antennas. Highly-directional antennas are typically concave, dish-shaped devices, as can be seen Figures 3. 10 and 3. 11. These antennas are ideal for long distance, point-to-point wireless links. Some models are referred to as parabolic dishes because they resemble small satellite dishes. Others are called grid antennas due to their perforated design for resistance to wind loading. Figure 3. 10: sample of a highly directional antenna Figure 3. 11: sample of a highly directional grid antenna Figure 3. 12: Radiation pattern of a highly directional antenna Usages High-gain antennas do not have a coverage area that client devices can use. These antennas are used for point-to-point communication links, and can transmit at distances up to 25 miles. Potential uses of highly directional antennas might be to connect two buildings that are miles away from each other but have no obstructions in their path. Additionally, these antennas can be aimed directly at each other within a building in order to â€Å"blast† through an obstruction. This setup would be used in order to get network connectivity to places that cannot be wired and where normal wireless networks will not work. 0 3. 2. 4 Antenna Gain An antenna element without the amplifiers and filters typically associated with it is a passive device. There is no conditioning, amplifying, or manipulating of the signal by the antenna element itself. The antenna can create the effect of amplification by virtue of its physical shape. Antenna amplification is the result of focusing the RF ra diation into a tighter beam, just as the bulb of a flashlight can be focused into a tighter beam creating a seemingly brighter light source that sends the light further. The focusing of the radiation Measured by way of beam widths, which are measured in degrees horizontal and vertical. For example, an omni-directional antenna has a 360-degree horizontal beam width. By limiting the 360-degree beam width into a more focused beam of, say, 30 degrees, at the same power, the RF waves will be radiated further. This is how patch, panel, and Yagi antennas (all of which are semi-directional antennas) are designed. Highly directional antennas take this theory a step further by very tightly focusing both horizontal and vertical beam widths to maximize distance of the propagated wave at low power. . 2. 5 Intentional Radiator As defined by the Federal Communication Commission (FCC), an intentional radiator is an RF device that is specifically designed to generate and radiate RF signals. In terms of hardware, an intentional radiator will include the RF device and all cabling and connectors up to, but not including, the antenna, as illustrated in Figure 3. 13 below . Figure 3. 13: Intentional Radiator Any reference to â€Å"power output of the Intentional Radiator† refers to the power output at the end of the last cable or connector before the antenna. For example, consider a 30- milliwatt transmitter that loses 15 milliwatts of power in the cable and another 5 milliwatts from the connector at the antenna. The power at the intentional radiator would be 10 milliwatts. As an administrator, it is your responsibility to understand the FCC rules relating to Intentional Radiators and their power output. Understanding how power output is measured, how much power is allowed, and how to calculate these values are all covered in this book. FCC regulations concerning output power at the Intentional Radiator and EIRP are found in Part 47 CFR, 1 3. 2. 6 Equivalent Isotropically Radiated Power (EIRP) EIRP is the power actually radiated by the antenna element, as shown in Figure 3. 14. This concept is important because it is regulated by the FCC and because it is used in calculating whether or not a wireless link is viable. EIRP takes into account the gain of the antenna. Figure 3. 14: Equivalent Isotropically Radiated Power Suppose a transmittin g station uses a 10-dBi antenna (which amplifies the signal 10fold) and is fed by 100 mill watts from the intentional radiator. The EIRP is 1000 mW, or 1 Watt. The FCC has rules defining both the power output at the intentional radiator and the antenna element. 3. 3 RF Accessories When wireless LAN devices connect together, the appropriate cables and accessories need to purchase that will maximize throughput, minimize signal loss, and, most importantly, allow making connections correctly. Different types of accessories are needed in a wireless LAN design. [7] 1. RF Amplifiers 2. RF Attenuators 3. Lightning Arrestors 4. RF Connectors 5. RF Cables 3. 3. 1 RF Amplifiers An RF amplifier is used to amplify, or increase the amplitude of, RF signal, which is measured in +dB. An amplifier will be used when compensating the loss incurred by the RF signal, either due to the distance between antennas or the length of cable from a wireless infrastructure device to its antenna. Most RF amplifiers used with wireless LANs are powered using DC voltage fed onto the RF cable with an injector near the RF signal source (such as the access point or bridge). Sometimes this DC voltage used to power RF amplifiers is called â€Å"phantom voltage† because the RF amplifier seems to magically power up. This DC injector is powered using AC voltage from a wall outlet, so it might be located in a wiring closet. In this scenario, the RF cable carries 32 both the high frequency RF signal and the DC voltage necessary to power the in-line amplifier, which, in turn, boosts the RF signal amplitude. Figure 3. 15 shows an example of an RF amplifier (left), and how an RF amplifier is mounted on a pole (right) between the access point and its antenna. Figure 3. 15: A sample of a fixed gain Amplifier RF amplifiers come in two types: unidirectional and bi-directional. Unidirectional amplifiers compensate for the signal loss incurred over long RF cables by increasing the signal level before it is injected into the transmitting antenna. Bi-directional amplifiers boost the effective sensitivity of the receiving antenna by amplifying the received signal before it is fed into the access point, bridge, or client device. Configuration and Management RF amplifiers used with wireless LANs are installed in series with the main signal path seen below in Figure 3. 16. Amplifiers are typically mounted to a solid surface using screws through the amplifier’s flange plates. Configuration of RF amplifiers is not generally required unless the amplifier is a variable RF amplifier. If the amplifier is variable, the amplifier must be configured for the proper amount of amplification required, according to RF math calculations. The manufacturer' user manual will s explain how to program or configure the amplifier. Figure 3. 16: RF amplifier placement in the wireless LAN system 3. 3. 2 RF Attenuators An RF attenuator is a device that causes precisely measured loss (in dB) in an RF signal. While an amplifier will increase the RF signal, an attenuator will decrease it. Consider the case where an access point has a fixed output of 100mW, and the only antenna available is an omni-directional antenna with +20 dBi gain. Using this equipment together would violate FCC rules for power output, so an attenuator could be added to decrease the RF signal down to 30mW before it entered the antenna. This configuration would put the power output within FCC parameters. Figure 3. 17 shows examples of fixed-loss RF attenuators with BNC connectors (left) and SMA connectors (right). Figure 3. 18 shows an example of an RF step attenuator. 33 Figure 3. 7: Sample of a fixed loss Amplifier Figure 3. 18: A sample of a RF step attenuator (Variable loss) Configuration and Management Figure 3. 19 shows the proper placement in a wireless LAN for an RF attenuator, which is directly in series with the main signal path. Fixed, coaxial attenuators are connected directly between any two-connection points between the transmitter and the antenna. For example, a fixed, coaxial antenn a might be connected directly on the output of an access point, at the input to the antenna, or anywhere between these two points if multiple RF cables are used. Variable antennas are generally mounted to a surface with screws through their flange plates or simply placed in a wiring closet on a shelf. Configuration of RF attenuators is not required unless a variable attenuator is used, in which case, the amount of attenuation required is configured according to your RF calculations. Configuration instructions for any particular attenuator will be included in the manufacturer' user manual. s Figure 3. 19: RF attenuator placement in a wireless LAN 3. 3. 3 Lightning Arrestors A lightning arrestor is used to shunt transient current into the ground that is caused by lightning. Lightning arrestors are used for protecting wireless LAN hardware such as access points, bridges, and workgroup bridges that are attached to a coaxial transmission line. Coaxial transmission lines are susceptible to surges from nearby lightning strikes. Lightning arrestor are only needed for outdoor antennas that are 34 Susceptible to lighting sticks in the vicinity. They are not necessary for indoor antennas because of the existing building ground. A lightning arrestor can generally shunt surges up to 5000 Amperes at up to 50 volts. Lightning arrestor performs the following function 1. Lightning strikes a nearby object 2. Transient current are induced in the antenna or the RF transmission line 3. The lightning arrestor senses these currents and immediately ionizes the gases held internally to cause a short (a path of almost no resistance) directly to earth ground. Figure 3. 20: Lightning Arrestors installed in a network 3. 3. 4 RF Connectors RF connectors are specific types of connection devices used to connect cables to devices or devices to devices. Traditionally, N, F, SMA, BNC, and TNC connectors (or derivatives) have been used for RF connectors on wireless LANs. In 1994, the FCC and DOC (Canadian Department of Communications) ruled that connectors for use with wireless LAN devices should be proprietary between manufacturers [7]. For this reason, many variations on each connector type exist such as: 1. N-type 2. Reverse polarity N-type 3. Reverse threaded N-type Figure 3. 21: Sample N-type and SMA Connector 35 Choosing an RF Connector There are five things that should be considered when purchasing and installing any RF connector, and they are similar in nature to the criteria for choosing RF amplifiers and attenuators. . The RF connector should match the impedance of all other wireless LAN components (generally 50 ohms). 2. Know how much insertion loss each connector inserted into the signal path causes. The amount of loss caused will factor into your calculations for signal strength required and distance allowed. 3. Know the upper frequency limit (frequency response) specified for the particular connectors. This point will be very important as 5 GHz wireless LANs become more and more common. Some connectors are rated only as high as 3 GHz, which is fine for use with 2. GHz wireless LANs, but will not work for 5 GHz wireless LANs. Some connectors are rated only up to 1 GHz and will not work with wireless LANs at all, other than legacy 900 MHz wireless LANs. 4. Beware of bad quality connectors. First, always consider purchasing from a reputable company. Second, purchase only high-quality connectors made by name-brand manufacturers. This kind of purchasing particularity will help eliminate many problems with sporadic RF signals, VSWR, and bad connections. 5. Make sure you know both the type of connector (N, F, SMA, etc. ) that you need and the sex of the connector. Connectors come in male and female. Male connectors have a center pin, and female connectors have a center receptacle. 3. 3. 5 RF Cables Proper cables are needed for connecting an antenna to an access point or wireless bridge. Below are some criteria to be considered in choosing the proper cables for your wireless network. 1. Cables introduce loss into a wireless LAN, so make sure the shortest cable length necessary is used. 2. Plan to purchase pre-cut lengths of cable with pre-installed connectors. Doing minimizes the possibility of bad connections between the connector and the cable. Professional manufacturing practices are almost always superior to cables manufactured by untrained individuals. 3. Look for the lowest loss cable available at your particular price range (the lower the loss, the more expensive the cable). Cables are typically rated for loss in dB/100-feet. The table in Figure 5. 29 illustrates the loss that is introduced by adding cables to a wireless LAN. 4. Purchase cable that has the same impedance as all of your other wireless LAN components (generally 50 ohms). 5. The frequency response of the cable should be considered as a primary decision factor in your purchase. With 2. 4 GHz wireless LANs, a cable with a rating of at least 2. 5 GHz should be used. With 5 GHz wireless LANs, a cable with a rating of at least 6 GHz should be used. 36 Table 3. 1: Coaxial Cable attenuation ratings LMR Cable 100A 195 200 240 300 400 400UF 500 600 600UF 900 1200 1700 30 3. 9 2. 0 1. 8 1. 3 1. 1 0. 7 0. 8 0. 54 0. 42 0. 48 0. 29 0. 21 0. 15 50 5. 1 2. 6 2. 3 1. 7 1. 4 0. 9 1. 1 0. 70 0. 55 0. 63 0. 37 0. 27 0. 19 150 8. 9 4. 4 4. 0 3. 0 2. 4 1. 5 1. 7 1. 2 1. 0 1. 15 0. 66 0. 48 0. 35 220 10. 9 5. 4 4. 8 3. 7 2. 9 1. 9 2. 2 1. 5 1. 2 1. 0. 80 0. 59 0. 43 450 15. 8 7. 8 7. 0 5. 3 4. 2 2. 7 3. 1 2. 2 1. 7 2. 0 1. 17 0. 89 0. 63 900 22. 8 11. 1 9. 9 7. 6 6. 1 3. 9 4. 5 3. 1 2. 5 2. 9 1. 70 1. 3 0. 94 1500 30. 1 14. 5 12. 9 9. 9 7. 9 5. 1 5. 9 4. 1 3. 3 3. 8 2. 24 1. 7 1. 3 1800 33. 2 16. 0 14. 2 10. 9 8. 7 5. 7 6. 6 4. 6 3. 7 4. 3 2. 48 1. 9 1. 4 2000 35. 2 16. 9 15. 0 11. 5 9. 2 6. 0 6. 9 4. 8 3. 9 4. 5 2. 63 2. 0 1. 5 2500 39. 8 19. 0 16. 9 12. 9 10. 4 6. 8 7. 8 5. 5 4. 4 5. 1 2. 98 2. 3 1. 7 37 CHAPTER 4 Wireless LAN 38 Chapter 4 Wireless LAN 4. 1 Wireless LAN (WLAN) 4. 1. 1 Wireless LAN Linking of t

Haier

MGF 403 Assignment 4 Was Haier’s decision to globalize into developed markets early on a good strategy? Haier focus on difficult market first. In this context, difficult means developed and big for the market ,for example, Europe and United States markets . Zhang decides to aim for harder market first because he thinks that after Haier can conquer the developed market, the emerging or developing market should be relatively easy to penetrate. Besides, a lot of other Chinese firms is going towards the emerging markets such as Southeast Asia.Therefore, Haier has a different management in not doing what others do. It is a good thing that Haier distribute niche products and offer many different varieties in different markets with being responsive towards customers need and feedback. In this case, Haier learns in getting to know how the market behaves as well as the competitors around. Unfortunately, there are a few weaknesses in this strategy. First of all, Haier could not be in th e scale as the other big competitors therefore Haier will not receive a large market share in developed markets.Plus, Haier in the developed market is very new and unknown by people. In addition, certain foreign markets perceive Chinese products, especially in household appliances and electronic devices, as a relatively poor quality products. This is the first impression held by most people. Can Haier build on its success in niche products to become a dominant global brand in high-end white goods? As long as Haier try to adapt their product into the current objective market, such as the water test in the washing machines, fridge temperature, and voltage, they can gain customer recognition and satisfaction.However, in order to introduce Haier products into high-end white goods can be relatively difficult because there are still many big local companies that has the trend design and are more recognized by the people in the society. Well, starting from a unique niche product is a very good start to differentiate Haier brand to the other and promote Haier to the society. With Haier brand sounds familiar already, Haier can gradually increase its sales. And from that point onwards, Haier can control and monitor its business. Having said that Haier can do well in the specified market such as the student and offices refrigerators ,but Haier will face hallenge in launching all its standard white goods considering the outside factors. Is Haier’s â€Å"three thirds† strategy a viable or visible approach? Haier’s â€Å"three third† strategy comprises of one-third from goods produced and sold in China, one-third produced in China and sold overseas, and one-third produced and sold overseas. In order to analyze whether this strategy fits or not, we have to take a look at the market condition. If the objective market is a growing market, this strategy might apply well since we can monitor the allocation of resources and focus on important areas in the market.On the other hand, if the market that we choose is in mature stage, this strategy might not be a good option because the company will tend to focus on a certain area of the market and disregard the other. Additionally, if there is a market that outperform the other markets, the allocation of resources in the particular market will be given to the other lower market in order to achieve the equally one-third weighted goal among them. Therefore, the potential in getting more revenue at the outperforming market will be disrupted.

Suicide Note Essays - Suicide Note, Free Essays, Term Papers

Suicide Note Essays - Suicide Note, Free Essays, Term Papers Suicide Note Contemplation The poem, "Suicide Note," by Janice Mirikitani, depicts an Asian-American female college student who committed suicide by jumping out of her dormitory window. Her last words, thoughts, and feelings were left behind in a suicide note, describing why this had to happen. This was a tragic accident that should not have happened, in fact, it should have been prevented. What drove this college student to kill herself? Was it her fault, or was she pushed so far that it became too much for here to take? It is revealed throughout this suicide note the many reasons why she decided to end her life. The suicide note begins with the phrases, "not good enough," "not pretty enough," and "not smart enough" (3). These phrases are repeated over and over again, to prove to the reader that she was never appreciated or complemented for what she had to offer. No one had ever brought it to her attention that she was doing a good job, or that she looked pretty, or that she was smart. It showed that she was smart, she was just shy of a perfect four-point grade average. 2 The note goes on to state an apology to her parents. She felt as if she was disappointing them, by not working hard enough, and also "not good enough to please her parents" (7-9). Everything she had done seemed to be the best she could do, but to her parents, it wasn't good enough. She begins to fantasize about what it would be like if she were a son, "shoulders broad as the sunset threading through the pine" (10-11). Would she have gotten more attention? Would she then be praised for the jobs she has accomplished? Would it be good enough for her parents? Since she was a girl, her parents expected less from her. She tried to stand up and take charge, by doing chores and tasks that a boy would be required to do. Had she been a boy, her life would be a lot easier, and she would have gained more respect from her parents. She admits that "tasks did not come easy to her" (24). "Each failure, a glacier" (25). The glacier represents a big disappointment to her, as if it makes her feel cold inside, and she regrets that she could have done better. Further into the note, she pictures herself as a sparrow, "sillied and dizzied by the wind" (38-39). The reason she pictures herself as a sparrow is because a sparrow is a little bird that is not considered to be a really important creature. Compared to a hawk or an eagle, a sparrow is a peasant bird, or an everyday bird. People have noticed sparrows before, but have never pointed them out, like they would if it were a hawk or an eagle. They would praise the hawk or eagle, not a little sparrow. When people see a hawk or an eagle, they stop and say, 3 "Look!" or "Wow!" She obviously never got acknowledged for her work. She felt like she wasn't being appreciated. Near the end, she hopes that they will "bury her under a sturdy pine" (59). The pine refers back to the beginning where she pictures herself as a boy. The pine represents what would have happened if she would have turned out to be a boy. It could also mean that in the afterlife, she wants to be as strong as a pine, hoping that she will be brought back as a boy. The suicide was a way for the college student to finally be noticed. It was very unfortunate for a person to take their life just to get attention, and to finally get some appreciation for all the things she had done, which still wouldn't be good enough for her parents.

Dimensions of inter-professional practice The WritePass Journal

Dimensions of inter-professional practice Introduction Dimensions of inter-professional practice ). Each team member brings a different aspect and focus to an inter-professional meeting and each role is distinctive, the nursing role is unique in that they are closer to what is happening with the patient because they seem them daily and have more ‘human’ contact with them (NMC, 2006). Conclusion It is important to remember during inter-professional meetings that health professionals may not have the skills or attributes essential for inter-professional practice and may require education in order to learn how to collaborate (McCallin 2005). Developing inter-professional practice requires a commitment to engage in shared learning and dialogue. Dialogue has the potential to encourage collegial learning, change thinking, support new working relationships, and improve client care. Looking back I realise I should have mentioned Agnes’ dislike of vegetables rather than worrying that it was a trivial matter and staying quiet, the role of the nurse in an inter-professional meeting is not just to report on daily observations, but also to be the advocate of the patient, as nursing staff often develop closer relationships with the patient as they have more contact with them (RCN, 2010). Action plan I will seek to become more familiar with inter-professional team working to ensure than I become an effective member of the team. I will do this by talking to my peers and mentor on their experiences and what strategies they used to become part of the team.   I will also find out more about the roles of the other professionals and how what their disciplines work within the inter-professional team. To achieve this aim I will study the general roles of the other team members. I will also work on my assertiveness, as I realise that relevant information should be mentioned in inter-professional meetings, especially if it allows the patient to have a say in their care. Furthermore, in the future, if I have a student that I am mentoring I will ensure they have a good understanding of how inter-professional meetings can unfold and I will ensure they have a voice in these meetings so that they feel involved in the proceedings. References Boyd, E. M., Fales, A. W. (1983). Reflective learning: key to learning from experience. Journal of Humanistic Psychology, 23(2), 99-117. Castelli, P. (2011). An intergrated model for practicing reflective learning. Academy of Educational Leadership Journal, 15, 15-30 Department   of Health (2013) https://www.gov.uk/government/policies/improving-quality-of-life-for-people-with-long-term-conditions. Accessed 3/5/13 Gibbs, G., (1998). Learning by Doing: A Guide to Teaching and Learning Methods. Oxford: Further Education Unit, Oxford Brookes University. Grumbach K, Bodenheimer T. (2004) Can health care teams improve primary care practice? JAMA. Mar 10;291(10):1246-51. Hinchliff, S. Norman, S. Schober, J. Eds (2008) Nursing practice and healthcare. 5th ed. Oxford: Blackwell science Housley, W., (2003). Interaction in Multidisciplinary Teams. Ashgate Publishing Limited: England. Humphris D, Hean S. (2004) Educating the future workforce: building the evidence about interprofessional learning. J Health Serv Res Policy. Jan;9 Suppl 1:24-7. Kumar, K. (2011). Living Out Reflective Practice. Journal of Christian Nursing, 28(3), 139-143. Korner, M. (2008). Analysis and development of multiprofessional teams in medical rehabilitation. GMS Psychosocial Medicine, 5(13), 2. Leathard, A., (2003). Inter-professional Collaboration: from policy to practice in health and social care. Philadelphia: Brunner – Routledge. McCallin, A. (2005). Interprofessional practice: Learning how to collaborate. Contemporary Nurse: Vol. 20, No. 1, pp. 28-37. Martin, J.S., Ummenhofer, W., Manser, T., Spirig, R. (2010) Interprofessional collaboration among nurses and physicians: making a difference in patient outcome. Swiss Med Wkly. 1;140:w13062. Nice guidelines (2005) Guidelines for establishing and supporting working partnerships of patients and clinicians. https://www.evidence.nhs.uk/document?ci=http%3A%2F%2Farms.evidence.nhs.uk%2Fresources%2FHub%2F15565q=nice%20guidelines%20on%20interprofessional%20workingReturnUrl=%2Fsearch%3Fq%3Dnice%2520guidelines%2520on%2520interprofessional%2520working. Accessed 3/5/13 NMC (2008), Code of Conduct, Nursing and Midwifery Council, London NMC (2006) The role of nurses in interprofessional health and social care teams, The role of nurses in interprofessional health and social care teams Accessed 3/5/13 Ovretveit, J., Mathias, F., Thomoson, T. eds., (1997). Interprofessional working for health and social care. Hampshire: Macmillan Press Limited. Pollard, K., (2005). Interprofessional Working: an Essential Guide for Health and Social-Care Professionals; England, Nelson Thrones Limited. Royal College of Nursing (2010) Principles of Nursing Practice. RCN website. Accessed 3/5/13 Royeen, CB., Jensen, JM., Harvan, RA. (2011) Leadership in interprofessional health education and practice. Jones Bartlett Publishers Whitehead (2000) Education, behavioural change and social psychology: Nursing’s contribution to health promotion. Journal of Advanced Nursing, 34(6), 822-832

90 Verbs Starting with Ex-

90 Verbs Starting with Ex- 90 Verbs Starting with â€Å"Ex-† 90 Verbs Starting with â€Å"Ex-† By Mark Nichol Ex- marks the spot. Go beyond, go out on a limb, go outside your comfort zone. Get some extra excitement by using these vivid verbs starting with the syllable ex-: 1. Exacerbate: to make worse 2. Exact: to call for and obtain (â€Å"exact revenge†) 3. Exaggerate: to overemphasize or overstate 4. Exalt: to glorify or intensify 5. Examine: to inspect, investigate, or scrutinize 6. Exasperate: to aggravate or enrage 7. Excavate: to remove or expose by digging or as if by digging 8. Exceed: to be greater than or to go beyond a limit or normal boundary 9. Except: to keep out or to object 10. Excerpt: to take out or select, especially writing, for other use 11. Exchange: to trade 12. Excise: to remove by cutting or as if by cutting 13. Excite: to arouse or stimulate 14. Exclaim: to cry out passionately or vehemently 15. Exclude: to bar, or to prevent entrance or inclusion 16. Excogitate: to devise 17. Excommunicate: to bar from membership 18. Excoriate: to abrade or censure 19. Excrete: to discharge or eliminate 20. Excruciate: to torture 21. Exculpate: to clear of blame or fault 22. Excuse: to forgive or remove blame from or to justify or make an apology for 23. Execrate: to denounce 24. Execute: to carry out or perform 25. Exemplify: to embody or make an example of 26. Exempt: to set apart or release from a requirement 27. Exenterate: to disembowel 28. Exercise: to practice, train, or put to use 29. Exert: to put forth effort 30. Exfoliate: to cast off or remove 31. Exhale: to breathe out 32. Exhaust: to wear out 33. Exhibit: to show or demonstrate 34. Exhilarate: to refresh or stimulate 35. Exhort: to appeal to or to warn 36. Exhume: to disinter or to rectify neglect 37. Exile: to drive out 37. Exist: to continue to be or to have being 39. Exit: to go out 40. Exonerate: to reverse an accusation 41. Exorcise: to get rid of an evil spirit or something troublesome 42. Expand: to enlarge or spread 43. Expatiate: to wander, or to communicate at length 44. Expatriate: to banish, or to withdraw from residence or allegiance 45. Expect: to await or to suppose 46. Expectorate: to discharge or spit 47. Expedite: to cause to occur quickly, or to dispatch or issue 48. Expel: to eject 49. Expend: to spend, use up, or utilize 50. Experience: to learn or sense by direct participation or observation, or to undergo 51. Experiment: to test or try 52. Expiate: to absolve of guilt, or to make amends 53. Expire: to conclude or die, or to breath out 54. Explain: to make something known or understood or demonstrate knowledge or understanding 55. Explicate: to describe or analyze 56. Explode: to burst or give forth, or suddenly accelerate or increase 57. Exploit: to utilize, or to take advantage of knowledge 58. Explore: to analyze, investigate, or study, or to test or travel 59. Export: to carry, remove, or send 60. Expose: to make known, to show, or to subject to the elements or to view 61. Exposit: see expound 62. Expostulate: to discuss or examine 63. Expound: to argue, comment, or state 64. Express: to force out, to show, or to symbolize, or to offer feelings or opinions or to perform in order to demonstrate artistry and/or communicate creative material 65. Expropriate: to deprive of property or take another’s property for one’s own 66. Expulse: see expel 67. Expunge: to destroy or to strike out 68. Expurgate: to remove something objectionable 69. Exscind: to cut off or out 70. Exsert: to throw out 71. Exsiccate: to dry 72. Extemporize: to improvise 73. Extend: to put or send out 74. Extenuate: to mitigate or to reduce strength or effect 75. Exteriorize: to bring out from inside (as in surgery) 76. Exterminate: to get rid of or kill 77. Externalize: to rationalize, or to make manifest 78. Extinguish: to eclipse, nullify, or quench 79. Extirpate: to cut out, destroy, or uproot 80. Extol: to glorify or praise 81. Extort: to wring from, to obtain from by argument or intimidation 82. Extract: to draw out, remove, or select 83. Extradite: to deliver a fugitive from one jurisdiction to another 84. Extrapolate: to infer, expand on, or predict 85. Extravasate: to cause to escape, or to force out (as in surgery) 86. Extricate: to free or remove from difficulty, or to distinguish from 87. Extrude: to press or push out, or to shape 88. Exuberate: to demonstrate unrestrained joy 89. Exude: to diffuse or spread out, or to display obviously 90. Exult: to rejoice Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Vocabulary category, check our popular posts, or choose a related post below:10 Grammar Mistakes You Should Avoid"Have" vs "Having" in Certain Expressions50 Words with Alternative Spellings

Research Ethics in the Human Service Field Paper

Ethics in the Human Service Field - Research Paper Example This paper purports to discuss some of the more important legal and ethical implications. The first ethical requirement of the job is a high motivation on the part of the professional (NOHS, 2009). Since this profession demands a great degree of involvement and self motivation by the service provider, it is expected that the professional be fully committed to his job, and appropriately trained (NOHS, 2009). This means an effort in an ongoing training and educating lifestyle, so that the newer and better schemes and models of service provision can be adopted (NOHS, 2009). The professional needs to be well aware of the cultural diversity and differences in the society and community in which he is operating, so that he can keep his professional dealings in accordance with the societal norms (NOHS, 2009). He should impart equal respect and acceptance of all the various belief systems that his clients might present with. This is especially true of those professionals who are involved in direct relation with the clients, such as counselors and psychologists (NOHS, 2009). Whereas it is true that the professional is not expected to discriminate on the basis of demographic details, he is, nevertheless, expected to advocate for those classes of the society which are targeted, maligned, or otherwise marginalized (NOHS, 2009). It should be noted that every client is supposed to be treated equally by the service provider, who should abstain from bias or favoritism. Therefore, all personal interests should be kept at bay (NOHS, 2009). However, when it comes to protecting a client’s well being and dignity, the provider is bound to take a stand for the minorities or the targeted groups of

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

Mortgages - Essay Example According to Boleat and Coles, the common trend is that after getting a gainful employment and after completing studies, most people will always opt to buy a home which is consider a wise investment since the homeowners would soon avoid paying rent, which takes up a big chunk of a person’s total earning (18-19). It is because of this reason that mortgage products have become very popular across the world and they have enabled many people become homeowners. However, mortgage facilities present certain problems to the borrowers, which will be discussed in this present essay and even how they affect the economy of the United States. Secondly, the essay will discuss recent act of legislations or proposal by the United States’ federal government that pertains to the problems that would be highlighted. Current problems faced by mortgagors and even the mortgage industry The nature of mortgage facility is that the borrower pays a monthly premium plus interest which is flexible meaning that the rate of the interest may increase or decrease depending on the market condition. Baily stated that borrowers’ problems usually arise when the rate of interest in the mortgage market increases while their income, which they use to repay the mortgage, remains steady (68-71). This therefore, creates a scenario whereby the borrower is unable to satisfactory pay the monthly premiums and interest, which then forces the bank to enact the foreclosure agreement that would leave the borrower homeless. Such a problem derails the entire economic growth of the United States, which is still on a recovery phase, and unemployment is still an issue since according to Baily lower purchasing power by the consumers who are servicing high interest rate means low demand for goods and products (33-35). Boleat and Coles also lamented that presently borrowers have been locked with high interest rates despite the fact that the rates have significantly decreased with the improved perfo rmance of the economy after the 2008 to 2010 financial crisis. Banks are only willing to allow a customer to switch to a cheaper rate if they are additionally using other products offered by the bank. This practice violates the directive issued by the Financial Service Authority that required lenders to treat the ‘captive’ customers fairly (89-93). In regards to the banking industry, the main problem that they face is the increased regulation that was imposed on the industry especially with the new laws such as the Dodd-Frank law that requires banks to tighten their lending requirements (Boleat and Coles, 109-112). For example, while evaluating the suitability of a prospective borrower banks currently do not consider earnings that are variable such as bonuses and commissions of which in some profession they make up the biggest percentage of the total earnings of an individual. This has resulted into banks loosing potential business and at the same time denying potential borrowers the chance to have a mortgage product. Equally, the national economy also suffers because there is decrease in the demand for houses since not many people can get a mortgage product, and this generally fails to promote economic growth. New mortgage rules Christie wrote that early this year the United States’ federal government issued rules for the mortgage industry and they were simply aimed at protecting homeowners who were facing foreclosure. Among the new rules that were introduced are restrictions that prevent mortgage lenders from repossessing homes whose owners are currently seeking modification of their loans. Moreover, according to the new rules lenders cannot enact the foreclosure agreement until the borrower fails to make payments for more than 120 days. Secondly, the

Genetics exam question Essay Example | Topics and Well Written Essays - 1000 words

Genetics exam question - Essay Example y through the increased potential for arrest and conviction of criminal elements, critics contend that the system opens the door for a big brother type of abuse. Though the system may result in an increase in the conviction rate, the personal nature of DNA information should be subject to the same standards as medical history and should not be warehoused in a central government location. There is little public disagreement as to the value of DNA when prosecuting a criminal who may be responsible for a child abduction or rape. According to the government, "The national DNA database is a key police intelligence tool that helps to quickly identify offenders, make earlier arrests, secure more convictions, and provide critical investigative leads for police investigations" (The national DNA database 2007). However, as more people are entered into the database cross contamination of samples could make the information acquired unmanageable. In the case of property crimes, anyone who had been minimally in contact with the crime scene in the recent past could be considered a suspect (Linacre 2003, p.1841). This could potentially involve all of a stores recent customers if there was a break in or a robbery. While it may help to place the perpetrator on a list of suspects, it would also incriminate a large number of innocent bystanders. Though the current requirements for collecting samples is restricted to those people that have been implicated in a crime, the protections are being compromised by law enforcement practices. During a recent investigation into a sexual assault in South London, the police department wrote a letter to the local population requesting voluntary DNA samples. However, the voluntary aspect was framed in a coercive effort. The letter said in part, "Consider that the suspect is likely to refuse to provide a voluntary sample; catching him will be far easier if he is the only one" (cited in Lettice 2005). Innocent citizens may feel pressured into