The French Revolution Research Paper Example | Topics and Well Written Essays - 500 words

The French Revolution - Research Paper Example deas included unfair taxation, the gap that existed between the poor and the rich social groups and the American Revolution and finally independence declaration of America (Noonan, 1999). The people in the third estate social group had very little rights whether socially or politically. However, some of the educated persons such as doctors and lawyers, belonging to third estate social class were in a position to read all the upcoming new ideas made by the government from some philosophers such as John Lacke, Rousseau, and Montesquieu. These philosophers talked about a democratic government possessing freedoms and natural rights. Eventually, the people belonging to the third estate social group began questioning the France government using the standards stated by the philosophers and began to demand for equality and democracy in the country (Noonan, 1999). Unfair taxation was an economic cause of the revolution. Third estate comprised of doctors, lawyers, merchants, and peasants who faced heavy taxation in many things while the richest estates paid little or no taxes. This was unfair treatment considering that people from the richest estates had a lot of money, large plots of land and positions in the government and good interaction with the government. This unfair treatment of the third estate people angered them and made a prompt of the revolution. The social cause of the revolution was the large gap that existed between the rich people and the poor people. There were few members belonging to the first and second estates while third estate made up of the biggest population. However, the rich owned biggest portions of land while the poor had little portions of land yet they made the biggest population in the country. Prove of the gap between the rich and the poor, was unequal taxation for the rich and the poor. Politically, third est ate people did not have privileges and right to contribute in the then government yet the nobles and clergies had the right. The

Socialization Essay Example for Free

Socialization Essay Socialization can be defined from a dictionary as â€Å" a continuing process whereby an individual person acquires a personal identity and learns the norms, values, behavior and social skills appropriate to his or her social position†. Socialization is a continuous life process, but is in general divided into two very distinct groups: primary socialization and secondary socialization. But has socialization changed over the years? If so, what has been the driving force behind this change? Could it be because of the difference in the primary socialization in the home? Or perhaps the multicultural society in which we now live? Socialization occurs throughout life but is most effective in infancy and early childhood. Primary socialization occurs in the home between the parent and child. It is a process by which a child learns the cultural norms from their parents. Primary social groups are small intimate groups which include family, close friends, work colleagues and neighbors. It is from everyday group living with the family that a child gets his or her first introduction to acceptable norms of behavior, values, and morals. Ely Chinoy, in a 1960s standard textbook on sociology, says that socialization serves two major functions: On the one hand, it prepares the individual for the roles he is to play, providing him with the necessary repertoire of habits, beliefs, and values, the appropriate patterns of emotional response and the modes of perception, the requisite skills and knowledge. On the other hand, by communicating the contents of culture from one generation to the other, it provides for its persistence and continuity. —Chinoy, 1961: 75 The parent or guardian also passes on their views on language, customs, and religion in a comfortable informal way. The family acts as an agent of social control by teaching its members right from wrong and punishing it’s members for wrongdoing. One extremely interesting point of note about socialization is the prominence that is sited on mothers and the role that mothers play in the socialization process. We are told that it is mothers who are primarily involved in the earlier unconscious stage of socialization. However has this intimate relationship changed over the years? Undoubtedly the task of primary socialization has undergone immense change in the last thirty years. The rise of the â€Å"Celtic tiger† has meant the role of primary socialization has become harder to enforce. The increase in the numbers of women returning to the work force has influenced the way that socialization had previously been structured in the home. More and more children are being cared for by child minders or in creches. Thus this means that the role of primary socialization has become an area which involves a much wider circle of people. From the beginning of the past decade, the majority of children in this state where being cared for by their mother in the home. Today life and families are not so straight-laced. Families are a complex unit that incorporates ideas that never occurred in past generations. The ideals of a family consisting of a father: breadwinner and head of household, and a mother who was involved in mainly household tasks and the rearing of the children, where soon forgotten. Instead these where to be replaced with the new concepts of blended families, one or lone parent families, foster families and adopted families. Another major change in the life of the family that would influence primary socialization is the average number of children in the family. The decrease in the number of children in the average family home has changed the environment of the home dramatically. Parents now have fewer children than past generations. This in turn leads to parents having much more time to instill values, morals, religion and other customs in their children. The rise in children attending these playschools means that a child is exposed to secondary socialization at an earlier age. Secondary socialization is another example of how our socialization patterns have changed over time. Secondary socialization occurs in groups that are usually larger and more impersonal than primary groups. Members usually see each other on an infrequent basis, and these groups are not considered to be permanent. Examples are trade union memberships, religious and ethnic groups, pressure groups, voluntary organizations and the schooling system. This form of socialization is commonly introduced when a child starts school. It is a child’s first experience of formal teaching and reinforces his or her past knowledge from primary socialization. This type of socialization has shown great distinction from previous eras. The multicultural and ethnic times we live in have changed the way this eneration socializes. The school system has had a major role to play in this. According to Christine E. Sleeted, â€Å"during the 1960s, textbooks clearly featured experiences and viewpoints of white middle class and elite people, mainly men. Over the past twenty-five years textbooks have gone through phases of active revision†. (Christine E. Sleeter 1996: 91). The world in which this generation grows is wholly different to the more guarded and constrained world of the past. The integration of different cultures and ethnicities into Irish society has made a series of changes to the way we now socialize. Children are integrated into a society that incorporates the views of different races, religions and customs. For this reason the education system has undergone immense change and as Christine E. Sleeted insists, â€Å"almost any textbook published over the last ten years appears t be well integrated. Many teachers work to make their curricula multicultural†. The implications of this multicultural curriculum are the increase in the level of understanding and acceptance in society as a whole. (Christine E. Sleeter 1996:91). Similarly Antonia Darder claims that in liberal educational American schools they â€Å"strongly incorporate the central pedagogical themes of appropriation, subjectivity, and interionality, along with a strong humanistic emphasis on the uniqueness of the individual†. (Antonia Darder 1991:8). This vital socialization enables society to combat issues such as classism, racism and sexism. The change in the socialization process is incontrovertible. In both of the distinct areas of socialization; primary socialization and secondary socialization change has certainty occurred and is evident in the socialization patterns of the past decade. The substantial transformation of the family has impacted on the aspect of primary socialization. While it is evident from research that the secondary socialization process is adjusting and amending its teaching methods to incorporate a new multicultural generation. The combination of the two reformed socialization processes has undoutedly changed the way this generation sees society. Due to the new teachings of acceptance and equality, life has changed for people in Ireland to a life that incorporates and supports a diverse society.

Amplitude modulation

Amplitude modulation Amplitude modulation Amplitude modulation (AM) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent. For example, changes in the signal strength can be used to reflect the sounds to be reproduced by a speaker, or to specify the light intensity of television pixels. (Contrast this with frequency modulation, also commonly used for sound transmissions, in which the frequency is varied; and phase modulation, often used in remote controls, in which the phase is varied) In the mid-1870s, a form of amplitude modulation—initially called undulatory currents—was the first method to successfully produce quality audio over telephone lines. Beginning with Reginald Fessendens audio demonstrations in 1906, it was also the original method used for audio radio transmissions, and remains in use today by many forms of communication—AM is often used to refer to the mediumwave broadcast band (see AM radio). Forms of amplitude modulation As originally developed for the electric telephone, amplitude modulation was used to add audio information to the low-powered direct current flowing from a telephone transmitter to a receiver. As a simplified explanation, at the transmitting end, a telephone microphone was used to vary the strength of the transmitted current, according to the frequency and loudness of the sounds received. Then, at the receiving end of the telephone line, the transmitted electrical current affected an electromagnet, which strengthened and weakened in response to the strength of the current. In turn, the electromagnet produced vibrations in the receiver diaphragm, thus closely reproducing the frequency and loudness of the sounds originally heard at the transmitter. In contrast to the telephone, in radio communication what is modulated is a continuous wave radio signal (carrier wave) produced by a radio transmitter. In its basic form, amplitude modulation produces a signal with power concentrated at the carrier frequency and in two adjacent sidebands. This process is known as heterodyning. Each sideband is equal in bandwidth to that of the modulating signal and is a mirror image of the other. Amplitude modulation that results in two sidebands and a carrier is often called double sideband amplitude modulation (DSB-AM). Amplitude modulation is inefficient in terms of power usage and much of it is wasted. At least two-thirds of the power is concentrated in the carrier signal, which carries no useful information (beyond the fact that a signal is present); the remaining power is split between two identical sidebands, though only one of these is needed since they contain identical information. To increase transmitter efficiency, the carrier can be removed (suppressed) from the AM signal. This produces a reduced-carrier transmission or double-sideband suppressed-carrier (DSBSC) signal. A suppressed-carrier amplitude modulation scheme is three times more power-efficient than traditional DSB-AM. If the carrier is only partially suppressed, a double-sideband reduced-carrier (DSBRC) signal results. DSBSC and DSBRC signals need their carrier to be regenerated (by a beat frequency oscillator, for instance) to be demodulated using conventional techniques. Even greater efficiency is achieved—at the expense of increased transmitter and receiver complexity—by completely suppressing both the carrier and one of the sidebands. This is single-sideband modulation, widely used in amateur radio due to its efficient use of both power and bandwidth. A simple form of AM often used for digital communications is on-off keying, a type of amplitude-shift keying by which binary data is represented as the presence or absence of a carrier wave. This is commonly used at radio frequencies to transmit Morse code, referred to as continuous wave (CW) operation. In 1982, the International Telecommunication Union (ITU) designated the various types of amplitude modulation as follows: Designation Description A3E double-sideband full-carrier the basic AM modulation scheme R3E single-sideband reduced-carrier H3E single-sideband full-carrier J3E single-sideband suppressed-carrier B8E independent-sideband emission C3F vestigial-sideband Lincompex linked compressor and expander Example: double-sideband AM A carrier wave is modeled as a simple sine wave, such as: c(t) = Ccdot sin(omega_c t + phi_c),, where the radio frequency (in Hz) is given by: omega_c / (2pi)., For generality, C,and phi_c,are arbitrary constants that represent the carrier amplitude and initial phase. For simplicity, we set their respective values to 1 and 0. Let m(t) represent an arbitrary waveform that is the message to be transmitted. And let the constant M represent its largest magnitude. For instance: m(t) = Mcdot cos(omega_m t + phi)., Thus, the message might be just a simple audio tone of frequency omega_m / (2pi)., It is generally assumed that omega_m ll omega_c, and that min[ m(t) ] = -M., Then amplitude modulation is created by forming the product: y(t), = [A + m(t)]cdot c(t),, = [A + Mcdot cos(omega_m t + phi)]cdot sin(omega_c t). A,represents another constant we may choose. The values A=1, and M=0.5, produce a y(t) depicted by the graph labelled 50% Modulation in 4. For this simple example, y(t) can be trigonometrically manipulated into the following equivalent form: y(t) = Acdot sin(omega_c t) + begin{matrix}frac{M}{2} end{matrix} left[sin((omega_c + omega_m) t + phi) + sin((omega_c omega_m) t phi)right]., Therefore, the modulated signal has three components, a carrier wave and two sinusoidal waves (known as sidebands) whose frequencies are slightly above and below omega_c., Also notice that the choice A=0 eliminates the carrier component, but leaves the sidebands. That is the DSBSC transmission mode. To generate double-sideband full carrier (A3E), we must choose: A ge M., For more general forms of m(t), trigonometry is not sufficient. But if the top trace of 2 depicts the frequency spectrum, of m(t), then the bottom trace depicts the modulated carrier. It has two groups of components: one at positive frequencies (centered on + ωc) and one at negative frequencies (centered on − ωc). Each group contains the two sidebands and a narrow component in between that represents the energy at the carrier frequency. We need only be concerned with the positive frequencies. The negative ones are a mathematical artifact that contains no additional information. Therefore, we see that an AM signals spectrum consists basically of its original (2-sided) spectrum shifted up to the carrier frequency. For those interested in the mathematics of 2, it is a result of computing the Fourier transform of: [A + m(t)]cdot sin(omega_c t),,using the following transform pairs: begin{align} m(t) quad stackrel{mathcal{F}}{Longleftrightarrow}quad M(omega) \ sin(omega_c t) quad stackrel{mathcal{F}}{Longleftrightarrow}quad i pi cdot [delta(omega +omega_c)-delta(omega-omega_c)] \ Acdot sin(omega_c t) quad stackrel{mathcal{F}}{Longleftrightarrow}quad i pi A cdot [delta(omega +omega_c)-delta(omega-omega_c)] \ m(t)cdot sin(omega_c t) quad stackrel{mathcal{F}}{Longleftrightarrow} frac{1}{2pi}cdot {M(omega)} * {i pi cdot [delta(omega +omega_c)-delta(omega-omega_c)]} \ = frac{i}{2}cdot [M(omega +omega_c) M(omega -omega_c)] end{align} In terms of the positive frequencies, the transmission bandwidth of AM is twice the signals original (baseband) bandwidth—since both the positive and negative sidebands are shifted up to the carrier frequency. Thus, double-sideband AM (DSB-AM) is spectrally inefficient, meaning that fewer radio stations can be accommodated in a given broadcast band. The various suppression methods in Forms of AM can be readily understood in terms of the diagram in 2. With the carrier suppressed there would be no energy at the center of a group. And with a sideband suppressed, the group would have the same bandwidth as the positive frequencies of M(omega)., The transmitter power efficiency of DSB-AM is relatively poor (about 33%). The benefit of this system is that receivers are cheaper to produce. The forms of AM with suppressed carriers are found to be 100% power efficient, since no power is wasted on the carrier signal which conveys no information. Modulation index As with other modulation indices, in AM, this quantity, also called modulation depth, indicates by how much the modulated variable varies around its original level. For AM, it relates to the variations in the carrier amplitude and is defined as: h = frac{mathrm{peak value of } m(t)}{A} = frac{M}{A}, where M,and A,were introduced above. So if h = 0.5, the carrier amplitude varies by 50% above and below its unmodulated level, and for h = 1.0 it varies by 100%. To avoid distortion in the A3E transmission mode, modulation depth greater than 100% must be avoided. Practical transmitter systems will usually incorporate some kind of limiter circuit, such as a VOGAD, to ensure this. Variations of modulated signal with percentage modulation are shown below. In each image, the maximum amplitude is higher than in the previous image. Note that the scale changes from one image to the next. Amplitude modulator designs This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2008) This article only describes one highly specialized aspect of its associated subject. Please help improve this article by adding more general information. (October 2009) Circuits A wide range of different circuits have been used for AM, but one of the simplest circuits uses anode or collector modulation applied via a transformer. While it is perfectly possible to create good designs using solid-state electronics, valved (vacuum tube) circuits are shown here. In general, valves are able to more easily yield RF powers, in excess of what can be easily achieved using solid-state transistors. Most high-power broadcast stations still use valves. Anode modulation using a transformer. The tetrode is supplied with an anode supply (and screen grid supply) which is modulated via the transformer. The resistor R1 sets the grid bias; both the input and outputs are tuned LC circuits which are tapped into by inductive coupling Modulation circuit designs can be broadly divided into low and high level. Low level Here a small audio stage is used to modulate a low power stage; the output of this stage is then amplified using a linear RF amplifier. Advantages The advantage of using a linear RF amplifier is that the smaller early stages can be modulated, which only requires a small audio amplifier to drive the modulator. Disadvantages The great disadvantage of this system is that the amplifier chain is less efficient, because it has to be linear to preserve the modulation. Hence Class C amplifiers cannot be employed. An approach which marries the advantages of low-level modulation with the efficiency of a Class C power amplifier chain is to arrange a feedback system to compensate for the substantial distortion of the AM envelope. A simple detector at the transmitter output (which can be little more than a loosely coupled diode) recovers the audio signal, and this is used as negative feedback to the audio modulator stage. The overall chain then acts as a linear amplifier as far as the actual modulation is concerned, though the RF amplifier itself still retains the Class C efficiency. This approach is widely used in practical medium power transmitters, such as AM radiotelephones. High level With high level modulation, the modulation takes place at the final amplifier stage where the carrier signal is at its maximum Advantages One advantage of using class C amplifiers in a broadcast AM transmitter is that only the final stage needs to be modulated, and that all the earlier stages can be driven at a constant level. These class C stages will be able to generate the drive for the final stage for a smaller DC power input. However, in many designs in order to obtain better quality AM the penultimate RF stages will need to be subject to modulation as well as the final stage. Disadvantages A large audio amplifier will be needed for the modulation stage, at least equal to the power of the transmitter output itself. Traditionally the modulation is applied using an audio transformer, and this can be bulky. Direct coupling from the audio amplifier is also possible (known as a cascode arrangement), though this usually requires quite a high DC supply voltage (say 30 V or more), which is not suitable for mobile units. See also * AM radio * Mediumwave band used for AM broadcast radio * Longwave band used for AM broadcast radio * Frequency modulation * Shortwave radio almost universally uses AM, narrow FM occurring above 25MHz. * Modulation, for a list of other modulation techniques * Amplitude modulation signalling system (AMSS), a digital system for adding low bitrate information to an AM signal. * Sideband, for some explanation of what this is. * Types of radio emissions, for the emission types designated by the ITU * Airband * Quadrature amplitude modulation References * Newkirk, David and Karlquist, Rick (2004). Mixers, modulators and demodulators. In D. G. Reed (ed.), The ARRL Handbook for Radio Communications (81st ed.), pp.15.1-15.36. Newington: ARRL. ISBN 0-87259-196-4. Pulse-amplitude modulation From Wikipedia, the free encyclopedia Principle of PAM; (1) original Signal, (2) PAM-Signal, (a) Amplitude of Signal, (b) Time Overview Pulse-amplitude modulation, acronym PAM, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Example: A two bit modulator (PAM-4) will take two bits at a time and will map the signal amplitude to one of four possible levels, for example −3 volts, −1 volt, 1 volt, and 3 volts. Demodulation is performed by detecting the amplitude level of the carrier at every symbol period. Pulse-amplitude modulation is widely used in baseband transmission of digital data, with non-baseband applications having been largely superseded by pulse-code modulation, and, more recently, by pulse-position modulation. In particular, all telephone modems faster than 300 bit/s use quadrature amplitude modulation (QAM). (QAM uses a two-dimensional constellation). Usage of Pulse-amplitude modulation in Ethernet It should be noted, however, that some versions of the widely popular Ethernet communication standard are a good example of PAM usage. In particular, the Fast Ethernet 100BASE-T2 medium, running at 100Mb/s, utilizes 5 level PAM modulation (PAM-5) running at 25 megapulses/sec over two wire pairs. A special technique is used to reduce inter-symbol interference between the unshielded pairs. Later, the gigabit Ethernet 1000BASE-T medium raised the bar to use 4 pairs of wire running each at 125 megapulses/sec to achieve 1000Mb/s data rates, still utilizing PAM-5 for each pair. The IEEE 802.3an standard defines the wire-level modulation for 10GBASE-T as a Tomlinson-Harashima Precoded (THP) version of pulse-amplitude modulation with 16 discrete levels (PAM-16), encoded in a two-dimensional checkerboard pattern known as DSQ128. Several proposals were considered for wire-level modulation, including PAM with 12 discrete levels (PAM-12), 10 levels (PAM-10), or 8 levels (PAM-8), both with and without Tomlinson-Harashima Precoding (THP). amplitude modulation DEFINITION- Also see modulation. Amplitude modulation (AM) is a method of impressing data onto an alternating-current (AC) carrier waveform.The highest frequency of the modulating data is normally less than 10 percent of the carrier frequency.The instantanous amplitude (overall signal power) varies depending on the instantaneous amplitude of the modulating data. In AM, the carrier itself does not fluctuate in amplitude.Instead, the modulating data appears in the form of signal components at frequencies slightly higher and lower than that of the carrier.These components are called sidebands. The lower sideband (LSB) appears at frequencies below the carrier frequency; the upper sideband (USB) appears at frequencies above the carrier frequency.The LSB and USB are essentially mirror images of each other in a graph of signal amplitude versus frequency, as shown in the illustration.The sideband power accounts for the variations in the overall amplitude of the signal. When a carrier is amplitude-modulated with a pure sine wave, up to 1/3 (33 percent) of the overall signal power is contained in the sidebands.The other 2/3 of the signal power is contained in the carrier, which does not contribute to the transfer of data.With a complex modulating signal such as voice, video, or music, the sidebands generally contain 20 to 25 percent of the overall signal power; thus the carrier consumes 75 to 80 percent of the power.This makes AM an inefficient mode.If an attempt is made to increase the modulating data input amplitude beyond these limits, the signal will become distorted, and will occupy a much greater bandwidth than it should.This is called overmodulation, and can result in interference to signals on nearby frequencies. Analog modulation methods A low-frequency message signal (top) may be carried by an AM or FM radio wave. Common analog modulation techniques are: * Amplitude modulation (AM) (here the amplitude of the carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal) o Double-sideband modulation (DSB) Â § Double-sideband modulation with unsuppressed carrier (DSB-WC) (used on the AM radio broadcasting band) Â § Double-sideband suppressed-carrier transmission (DSB-SC) Â § Double-sideband reduced carrier transmission (DSB-RC) o Single-sideband modulation (SSB, or SSB-AM), Â § SSB with carrier (SSB-WC) Â § SSB suppressed carrier modulation (SSB-SC) o Vestigial sideband modulation (VSB, or VSB-AM) o Quadrature amplitude modulation (QAM) * Angle modulation o Frequency modulation (FM) (here the frequency of the carrier signal is varied in accordance to the instantaneous frequency of the modulating signal) o Phase modulation (PM) (here the phase shift of the carrier signal is varied in accordance to the instantaneous phase shift of the modulating signal) AMPLITUDE MODULATION How it works. We know that something as simple as a crystal diode (rectifier) can be used to capture sound from the air and put it into a pair of earphones or an amplifier and speaker. How can this work? We will cover that here and now. All AM (Amplitude Modulation) detectors work basically the same way. What is AM? What we can hear as audio is classically considered to be the frequency range between 20 and 20,000 cycles per second (here after referred to as cycles and abandoning hertz) which I have never liked). In reality most adults can only hear up to about 13,000 cycles. Most speakers cant reproduce anything lower than 30 cycles in spite of the exaggerated claims of proud owners. So lets be generous and call audio 30 to 15,000 cycles. Radio frequencies are between 8,000 cycles and 50,000 megacycles. Thats right there is a range of frequencies that depending on how they are treated can be audio or radio. The AM radio band begins at 540 kilocycles. For simplicity lets say that we want to transmit a 10,000 cycle tone on a radio transmitter operating on 250 kilocycles. The 250 kc transmitting frequency is called the carrier wave because it may be thought of as carrying the audio. The 10,000 cycle audio frequency is called the modulating frequency. We may get into side-bands later. In the above the upper wave is the modulating wave and three cycles of it can be seen. The lower wave is the modulated carrier wave and 75 cycles are visible. (You can count them for yourself or take my word for it.) Notice as the modulating wave goes up the total amplitude of the carrier wave (measured from negative peak to positive peak) goes up. As the modulating wave goes down the amplitude of the carrier wave goes down. When the modulating wave is at zero (the point where it begins and ends) the carrier wave is at its middle or unmodulated value. Think of the modulating wave as controlling a valve that the carrier wave is passing through. (I have direct conformation from England, thats why the British call tubes valves.) The carrier wave can then be sent to an antenna which radiates it out for all the world to hear. Detecting the signal Detection is the word applied to the process of recovering the audio frequencies from the radio frequency carrier. In the case of amplitude modulation it is very simple. All we need to do is to rectify the signal. Rectification is the process used in power supplies to change AC to DC. Its really quite similar for detecting radio signals. Compare the carrier wave in the below with the one in the above. The wave has been run through a rectifier which removed the bottom half of every cycle. If we draw a line connecting the peaks we have the original modulating signal back again. Connecting the peaks is done by using a capacitor to charge up to the peak value and discharge through a resistor just fast enough to follow the modulating frequency but not so fast as to cause a large variation at the carrier frequency. The frequencies chosen for this drawing are fairly close together to make it possible to see the individual cycles on your computer screen. When dealing with the AM broadcast band the carrier frequencies range from 540 kc to 1600 kc. 10,000 cycles is the absolute upper limit for audio on AM and most transmitters only make it to about 8,000 cycles. Look back at the diagram of the crystal set. Use your back button to return here. If you are familiar with power supply circuits you will recognize it as a half wave rectifier with a capacitor to filter out ripple. The resistor makes the capacitor discharge just fast enough but not too fast. A much more rigorous discussion of AM, including side bands, is available by clicking here. This includes not only AM but SSB and FM. AMPLITUDE MODULATION Amplitude modulation or AM as it is often called, is a form of modulation used for radio transmissions for broadcasting and two way radio communication applications. Although one of the earliest used forms of modulation it is still in widespread use today. The first amplitude modulated signal was transmitted in 1901 by a Canadian engineer named Reginald Fessenden. He took a continuous spark transmission and placed a carbon microphone in the antenna lead. The sound waves impacting on the microphone varied its resistance and in turn this varied the intensity of the transmission. Although very crude, signals were audible over a distance of a few hundred metres, although there was a rasping sound caused by the spark. With the introduction of continuous sine wave signals, transmissions improved significantly, and AM soon became the standard for voice transmissions. Nowadays, amplitude modulation, AM is used for audio broadcasting on the long medium and short wave bands, and for two way radio communication at VHF for aircraft. However as there now are more efficient and convenient methods of modulating a signal, its use is declining, although it will still be very many years before it is no longer used. What is amplitude modulation? In order that a radio signal can carry audio or other information for broadcasting or for two way radio communication, it must be modulated or changed in some way. Although there are a number of ways in which a radio signal may be modulated, one of the easiest, and one of the first methods to be used was to change its amplitude in line with variations of the sound. The basic concept surrounding what is amplitude modulation, AM, is quite straightforward. The amplitude of the signal is changed in line with the instantaneous intensity of the sound. In this way the radio frequency signal has a representation of the sound wave superimposed in it. In view of the way the basic signal carries the sound or modulation, the radio frequency signal is often termed the carrier. What is amplitude modulation, AM Amplitude Modulation, AM When a carrier is modulated in any way, further signals are created that carry the actual modulation information. It is found that when a carrier is amplitude modulated, further signals are generated above and below the main carrier. To see how this happens, take the example of a carrier on a frequency of 1 MHz which is modulated by a steady tone of 1 kHz. The process of modulating a carrier is exactly the same as mixing two signals together, and as a result both sum and difference frequencies are produced. Therefore when a tone of 1 kHz is mixed with a carrier of 1 MHz, a sum frequency is produced at 1 MHz + 1 kHz, and a difference frequency is produced at 1 MHz 1 kHz, i.e. 1 kHz above and below the carrier. If the steady state tones are replaced with audio like that encountered with speech of music, these comprise many different frequencies and an audio spectrum with frequencies over a band of frequencies is seen. When modulated onto the carrier, these spectra are seen above and below the carrier. It can be seen that if the top frequency that is modulated onto the carrier is 6 kHz, then the top spectra will extend to 6 kHz above and below the signal. In other words the bandwidth occupied by the AM signal is twice the maximum frequency of the signal that is used to modulated the carrier, i.e. it is twice the bandwidth of the audio signal to be carried. Amplitude demodulation Amplitude modulation, AM, is one of the most straightforward ways of modulating a radio signal or carrier. The process of demodulation, where the audio signal is removed from the radio carrier in the receiver is also quite simple as well. The easiest method of achieving amplitude demodulation is to use a simple diode detector. This consists of just a handful of components:- a diode, resistor and a capacitor. AM diode detector AM Diode Detector In this circuit, the diode rectifies the signal, allowing only half of the alternating waveform through. The capacitor is used to store the charge and provide a smoothed output from the detector, and also to remove any unwanted radio frequency components. The resistor is used to enable the capacitor to discharge. If it were not there and no other load was present, then the charge on the capacitor would not leak away, and the circuit would reach a peak and remain there. Advantages of Amplitude Modulation, AM There are several advantages of amplitude modulation, and some of these reasons have meant that it is still in widespread use today: * It is simple to implement * it can be demodulated using a circuit consisting of very few components * AM receivers are very cheap as no specialised components are needed. Disadvantages of amplitude modulation Amplitude modulation is a very basic form of modulation, and although its simplicity is one of its major advantages, other more sophisticated systems provide a number of advantages. Accordingly it is worth looking at some of the disadvantages of amplitude modulation. * It is not efficient in terms of its power usage * It is not efficient in terms of its use of bandwidth, requiring a bandwidth equal to twice that of the highest audio frequency * It is prone to high levels of noise because most noise is amplitude based and obviously AM detectors are sensitive to it. Summary AM has advantages of simplicity, but it is not the most efficient mode to use, both in terms of the amount of space or spectrum it takes up, and the way in which it uses the power that is transmitted. This is the reason why it is not widely used these days both for broadcasting and for two way radio communication. Even the long, medium and short wave broadcasts will ultimately change because of the fact that amplitude modulation, AM, is subject to much higher levels of noise than are other modes. For the moment, its simplicity, and its wide usage, mean that it will be difficult to change quickly, and it will be in use for many years to come

Moral and Ethical Issues of Euthanasia Essay -- Euthanasia Physician A

Moral and Ethical Issues of Euthanasia    As we all know, medical treatment can help save lives. But is there a medical treatment that would actually help end life? Although it's often debated upon, the procedure is still used to help the aid of a patient's death. Usually dubbed as mercy killing, euthanasia is the "practice of ending a life so as to release an individual from an incurable disease or intolerable suffering" (Encarta). My argument over this topic is that euthanasia should have strict criteria over the use of it. There are different cases of euthanasia that should be looked at and different point of views that should be considered. I will be looking into VE (Voluntary Euthanasia), which involves a request by the dying patient or that person's legal representative. These different procedures are as follows: passive or negative euthanasia, which involves not doing something to prevent death or allowing someone to die and active or positive euthanasia which involves taking deliberate action to cause a death. I have reasons to believe that passive or negative euthanasia can be a humane way of end suffering, while active or positive euthanasia is not. According Richard Gula, active euthanasia is legally considered homicide (5). Another intervention and approach to euthanasia could be through the use of analgesic means. The use of morphine or other anesthetic medication could be used to allow the patient to die or hasten their dying process. I consider the latter procedure to be more humane than that of the other because it is morally wrong to kill a person, rather it's humane for someone to die naturally. Before I discuss the rights and wrongs of euthanasia, I will define death or a person, when is it safe to say... ...Jack D. "Euthanasia." Microsoft ® Encarta ® 98 Encyclopedia.  © 1993-1997: Microsoft Corporation. CD-ROM. Frederick, Calvin J. "Death and Dying." Microsoft ® Encarta ® 98 Encyclopedia.  © 1993-1997: Microsoft Corporation. CD-ROM. Gula, Richard M. What Are They Saying About Euthanasia?. Mahwah, NJ: Paulist Press, 1986. McGee, Glenn and Arthur L. Caplan. "Medical Ethics." Microsoft ® Encarta ® 98 Encyclopedia.  © 1993-1997: Microsoft Corporation. CD-ROM. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. Defining Death: A Report on the Medical, Legal and Ethical Issues in the Determination of Death. Washington, D.C.: U.S. Government Printing Office, 1981. Robert Matz; Daniel P. Sudmasy; Edward D. Pallegrino. "Euthanasia: Morals and Ethics." Archives of Internal Medicine 1999: p1815 Aug. 9, 1999 .

Mouth Cavity of Pig

Mouth Cavity Mouth: Opening into the oral cavity. Where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process (breaking down the food). Teeth: Used to break food down by (chewing) into smaller particles. Tongue: is used to manoeuvre food that is being chewed. Pharynx: tube-like structure that connects oral and nasal cavities to the larynx; provides passageway for respiratory and digestive tracts. Located in the back of the oral cavity. Esophageal opening: The entrance to the esophagus (food tube) can also be found in the nasopharynx. Esophagus- A muscular tube. The passage of food (via peristalsis) from the pharynx to the stomach. The esophagus is located dorsal to the trachea Nasopharynx opening: Passageway between the oralpharynx (throat) and the nasopharynx (nasal cavity) Nasopharynx: The nasopharynx is located above the part of the pharynx that food enters. Located just above the throat where food enters, the nasopharynx is connected to the middle ear, and it's purpose is to equalize ear pressure. And to allow air passage? Hard palate: hard bony structure that makes up the roof of the mouth. This separates the oral cavity from the nasal cavity. Soft palate: The movable fold, at the rear of the hard palate that closes off the nasal cavity from the oral cavity during swallowing or sucking. Epiglottis : a cone-shaped structure at the back of the mouth. fleshy flap the covers the glottis (which leads to the trachea) to prevent food and liquid from entering the trachea during swallowing. Glottis: The opening between the vocal cords at the upper part of the larynx.

Take It Easy Quotes to Live By

Take It Easy Quotes to Live By Just about everybody feels rushed and stressed at times. Since we all know that stress can be harmful to our health, nows the time to take steps to reduce the amount of stress in our lives. Slow down as you do things. Accept that what has passed  is past. Take one step at a time instead of multitasking your way through the day. Identify  what you are doing when you feel totally relaxed and focus on these activities instead of ones that stress you out. No one can avoid all the stress in life, but you can cut back on it. Chill Out With These Quotes Jim MorrisonTime to live, time to lie, time to laugh and time to die. Take it easy baby. Take it as it comes. Christian Nestell BoveeThere is a German proverb which says that Take-it-Easy and Live-Long are brothers. David SelznickWhy do you knock yourself out? Take it easy. Elbert HubbardDo not take life too seriously; you will never get out of it alive. Johnny CashI recently found myself going through a period of uncertainty about my future as a performer, my status as a personality, the believability of my Christian witness and the knowledge of Gods will in my life. I felt a force bigger than myself saying, Lay back. Take it easy. Study hard. Read your Bible. Think, write and keep your mouth shut for awhile. Kate JacobsIts all about getting the hang of things. Easy does it; take it easy. Youll figure everything out in time. But for right now, just keep trying. Pay attention and avoid the temptation to go further than youre ready. Talk less. And listen more. Martin ScorseseThe problem with anger is that its so consuming. Youve got to take it easy on yourself at a certain point. Robert BreaultIts not that Im a Type-B personality. Its that Im driven by a passionate, all-consuming desire to take it easy. Jack Kerouac ï » ¿So long and take it easy, because if you start taking things seriously, it is the end of you. Jackson BrowneLighten up while you still can, dont even try to understand. Just find a  place to make your stand, and take it easy. Fats WallerTake it easy, be a sport. Just remember life is short. Oscar WildeLife is too important to be taken seriously. Ryan ReynoldsI see guys with, like, eyebrow art, and I wanna tell them, You dont have to go too crazy on your brows. Take it easy, man! Golda MeirMy dear, old age is like an airplane flying in a storm. Once youre in it, theres nothing you can do. You cant stop a plane, you cant stop a storm, you cant stop time. So you might as well take it easy, with wisdom. Mark GormanOnly 8 percent of our worry will come to pass. 92 percent of our worry is wasted. Dont panic!