A Discussion of the Strategic Management Practice in Facebook

Fractured Franchise

Fractured Franchise Free Online Research Papers Reading of the article by Louis Menand only entrenched my attitude towards the issue concerning the right to vote. I do believe that the right to vote should be restricted in a way that only well-informed voters disposing of a sufficient knowledge of political situation would be recognized as being able to decide on political issues. Even if Caplan argues mostly within the framework of economic issues, his arguments remain plausible also in politics. The universal right to vote may not be a significant problem in developed democracies, whereas in the countries that have experienced other regimes this issue becomes more sensible. This is mainly because, apart from what Caplan wrote about individual rational choice to be ignorant because of the low price of voting, the fact that the elderly population would vote only because participation (and consent, indeed) used to be their civic duty. Since those people, who form the majority of the electoral public in Slovakia, for example, are convinced that they are obliged to vote, their motivation to inform themselves on the political situation is practically zero. Even if they believe being informed and form their political opinion, the risk that they do not consider all of the consequences of their opinion remains present. This is true not only for the elderly population, but also for most of the voting public. I agree with Caplan that the argument of collective intelligence is not valid, and that not only because democracy is not similar to market in it`s structure, but also because another condition for the collective intelligence to take place is that the collective should not be affected by no authority (in a case where they are affected, the result radically changes). The idea of â€Å"shortcuts† in decision-making obstructs the realisation of this condition. Also, I agree with Caplan`s statement that people tend to demand the preservation of the current status-quo. This means that the voters tend to stick to the experienced policies that did not cause much harm instead of wanting the adoption of policies that may improve the political situation and lead to the pursuit of their self-interest. This is why I believe that the right to vote should be limited only to those, who are actually concerned about politics and have sufficient knowledge on the issues they want to decide about. Even if many claim that democracy should be absolute and that the solutioin for all problems of democracy is more democracy, I do believe that they misunderstood it`s principles. Democracy, as I see it, is based on the equality of inputs, it means that everyone should have the right to be informed on the political situation, everyone should have an equal chance to get the right to vote. The universal right to vote is going beyond this and harms the system. Research Papers on Fractured FranchiseBringing Democracy to AfricaHip-Hop is ArtQuebec and Canada19 Century Society: A Deeply Divided EraRelationship between Media Coverage and Social andPETSTEL analysis of IndiaCapital PunishmentAssess the importance of Nationalism 1815-1850 EuropeEffects of Television Violence on ChildrenThe Project Managment Office System

Women Lives during World War I Era Essay Example | Topics and Well Written Essays - 500 words

Women Lives during World War I Era - Essay Example As mentioned above, women could vote after the realization of the 1920s’ 19th Amendment giving them the right to vote after a long struggle, protests, and movements directed to this right. There was a gap formed between the modern women in the 1920s versus the previous generation. There were strong stereotypes prior to that amendment that emphasized that women could not multitask on both their families and careers, which was reversed in this era. There was evidence of reduced investment in the entire social services compared to the progressive generations. This tune of the capitalistic spirited era saw the woman eager to find and compete with her personal fulfillment.Among other changes in the 1920s, women WWI allowed females to indulge themselves in temporarily in industries such as those processing automobiles, chemical, steel or iron manufacturing that some time back were deemed inappropriate for them. The race was also on the verge of being concerned in work premises where black women had started to find employment slots in industries, temporarily, during the First World War although on low wages although time saw them put back labor force consisting of agriculture, laundry works, and domestic servant at 75% in the 1920s.The suffrage achievements led the feminists to refocus their efforts to new goals where groups such as the NWP, National Women’s Party, carried on the political struggle with proposals such as the Equal Rights Amendment of 1923.

Importance of The Glorious Qur'an Essay Example | Topics and Well Written Essays - 2500 words

Importance of The Glorious Qur'an - Essay Example Introduction. The Qur’an is the holy text which holds the fundamental ideas underlying the Muslim faith as it is practised across the world. It holds a special place in the lives of Muslims because it is believed to be the word of Allah Himself, as revealed to the Prophet, Muhammad, and written down for the benefit of all who wish to learn from it. This paper examines the origins of this special book and summarizes its main contents. It then explores the importance of the Qur’an throughout history, in earliest times, and then in the twentieth century. Finally there is an examination of the Qur’an’s impact on the world today and the prospect of its continuing influence on the world in the future, along with a summarizing conclusion regarding the overall importance of the glorious Qur’an in human history. The Origins of The Glorious Qur’an. There is a huge gap in the understanding of men and the understanding of Allah, which cannot be bridged b y human intelligence. While Allah is good and merciful, human beings are easily distracted, and can achieve a mixture of good and bad things in their lives. It is perhaps for this reason that the Qur’an was given to mankind: it is a collection of revelations which are intended to guide human beings into the ways of peace and goodness. Other religions, and in particular Judaism and Christianity, also have their sacred texts, which have many elements in common, since these three religions are among the ahl-al-kitab (people of the book). The Qur’an is the particular holy book that was given to Muslims, and its name means â€Å"recitation†, implying that the prophet Muhammad did not invent the words himself, but in fact recited the words of Allah (Sonn, 2010, p. 1) Although the words of the Qur’an may have been first written down by listeners at various points in the lifetime of Muhammad, the text that Muslims now use has been carefully arranged by scholars a fter Muhammad’s death in 632 CE. The text is divided into 114 surah (chapters) each of which has a title, and a number of ayat (verses). It is written in Arabic, the language of Muhammad’s native land, and from the very beginning scholars have taken great care to preserve the exact and correct form of words that was used from the very beginning. A minor addition was made in the ninth century when scholars added some marks to indicate vowels, because the existence of different dialects of Arabic meant that ambiguities and differences could creep into the reading of the text in different places. (Sonn, 2010, p. 5) Muhammad himself taught believers read the text, and also learn it word for word, and be able to recite it so that the message is preserved complete and unchanged in their minds. This tradition was continued by Muslims after his death, leading to the formation of mosques and schools dedicated to passing on the knowledge of the Qur’an to future generation s. Muslims treat the actual text of the Qur’an with the deepest respect, and make use of portions for decorative and ceremonial purposes. There are additional sacred texts, known as the hadith which gather together some of the sayings of Muhammad and these are often

Time Traveling, Art Historian Book Chapters Essay

Time Traveling, Art Historian Book Chapters - Essay Example As I step into the machine, I think of the periods of time and the great works that will be there when I arrive. I took the greatest care in detail, the clothing prepared, my language skills perfectly honed to a time and place, as well as history can inform me, although I am sure things will not be fully as I expect them to be once I arrive. I sit into the contraption, its cold steel lying under its camouflage, an exterior that seems to be a wooden platform with a structure around it, resembling something of a small shack to be set down in out of the way alleys, calculated to exist, or within outlying avenues that support the nature of such a building. The shack would fool anyone who looked at it, its nature defined by its purpose. I step into the machine, the slight hum filling my ears and buzzing my senses as it begins to move through time. I have set the dials under the panel so that I will appear where I desire, and then stand in the center, closing my eyes because the feeling of moving through time disturbs my sight, a detail that most others do not feel when they are given the privilege of using the machine. I cannot wait to see this place, the time and moment that I have decided to enter Rome, her majesty impressive in the present, which will most likely impress me more in its past. My eyes shut, I let the hum move over me until it stills, and I assume that I have entered the right space and time, the slight strange clunk as I appear affirming the very human need for noise, something to announce to the rider that he or she has arrived. The sound, very much like the clicks on a computer as one touches the button, the noise created just to appease the user. Chapter One The Sistine Chapel I cautiously open the door, seeing that I have arrived in the alley as I expected, stepping out of the machine, I see that it looks very naturally, like a makeshift shack that was erected to temporarily house someone of no means from bits and scraps. I can see that it is n ot, but most people who would not know that it was there, would not think anything, or at least much, about its presence. As I take a breath, it feels like for a moment it is knocked from me as quickly as I breath in, the scent of the city foreign, both lacking something and feeling something added, my hand automatically coming up to cover my mouth as I try to adjust to the odor. The lack of automobiles assaults my senses as I draw in a breath, feeling it catch from its foreign taste as it hits the back of my throat. It takes a few minutes for me to be able to breath more easily, which then leads me to feel the discomfort of my clothing, heavy and cumbersome now that I am out of the air conditioned lab and in the air of the year 1511. As I step into the streets of Rome, I realize that more than just time changes from period to period. The air, the feel of the sun as it beats down to a still protected earth, the ozone layer still intact and providing filtration, all make a difference in the taste of life during that time period. Italy has that natural glow of amber, as if the olives have broken open and become airborne, and this is heavier and more beautiful than I have ever experienced in modern day Rome. I ache to see the countryside and experience its beauty, pure and whole before technology stripped it of its beauty, but I have a task that I must accomplish. I must see the Sistine Chapel before it was the Sistine Chapel and still the reconstructed Capella Magna, letting my eyes rest upon the newly painted

High Power Continuous Wave Fiber Laser System

High Power Continuous Wave Fiber Laser System Introduction of High Power Fiber Laser The optical fiber with very high surface-to-volume ratio and a strong waveguide effect provides the fiber based laser source the potential to generate high power laser beam with high quality. In addition to the capacity of generating raw optical power with high beam quality, the fiber laser system has other appealing features, such as supporting robust and compact system designs, allowing ultrashort pulse operation, offering a board wavelength tunability, and providing high gains. Those features stimulate the research on the high power fiber lasers system, and lay the foundation of novel appealing applications, such as remote material processing, aerospace and defense. In the past decade, a remarkable increase of the powers produced by fiber lasers with high beam quality has been achieved (see Fig.1). As a result, the high power laser becomes strong counterpart of the solid-state bulk laser, and penetrates rapidly into areas that formerly other lasers were used. Literature Review In the early 1960s, the first fiber laser was demonstrated by Snitzer. The doped fibers potential for high optical gain was revealed by David Payne and co-researchers working on Neodymium- doped fibers in mid 1980s . In 2009, the high power fiber laser, which based on a specifically silica-host ytterbium-doped fiber-based laser (YDFL), obtained 10 kW output in the single-mode (SM) regime. Although architectures are different, the high-power fiber lasers and amplifiers are mostly archived with rare-earth-doped (RE-doped) double-clad fibers. The double-clad fiber, which was initially demonstrated in 1988, provided the option of cladding pumping, and proved to be one of the key technologies for power scaling. The structure of this double cladding is that the active RE-doped core is surrounded by a much larger inner cladding (see Fig. 2), and are encircled together by out cladding. The pump beam emitted by fiber-coupled high-power diode bars or other kinds of laser diodes is coupled into the inner cladding, and confined within it by an outer cladding. The confined pump beam will be absorbed into the core while it propagates along the fiber. The laser light is generated in the central core, and the laser light can have very good beam quality even diffraction limited beam. Thereby, by means of double cladding configurations one realized the conversion from low brightness p ump to high brightness single-mode fiber laser output. As the spatial and angular pump acceptance [can be expressed as the product of area and the square of the numerical aperture (NA)] for the inner cladding is significantly improved to the core pump, Such conversion is more effective, and close to 5 orders have been demonstrated experimentally. Among high power RE-doped fiber lasers, the YDFL is notable in term of high power. The Ybs broad absorption band extends from 900 to 980 nm (see fig 3), covering high power pump LDs best performance wavelengths, offers a low quantum defect [energy difference between pump and laser photons] for pumping with 9xx nm LD and lasing above 1040nm. This superior property offers the potential for achieving very high power efficiencies and reducing thermal effects. In addition, lasing at wavelength above 1040nm, the Yd ion shows a simple four level structure, that excludes excited state absorption and also a variety of detrimental quenching processes allowing high doping concentrations, which means high pump absorption per unit length. On the contrary, the small quantum defect also has a usually unwanted consequence: the significant quasi-three-level behavior, especially when lasing at short wavelengths (less then 1040nm), that will cause a high threshold and decrease the power efficiency. Fig. 2. Structure of a double-clad fiber and principle of cladding-pumping The Nd doped laser emitting at 1060 nm is a four-level system, which means a lower laser threshold. Associated with the relatively advanced state of 808 nm diodes for pumping Nd:YAG, this made Nd the choice for high power fiber lasers in early stage. Todays high power pump diodes in 9 xx nm are sufficiently bright to make threshold unimportant for most quasi-three-level high power fiber lasers. These overcome the obstacle of ytterbiums higher threshold and raise advantages of a lower quantum defect and higher doping concentration with quench-free. The first single-mode Yb doped fiber laser with output power over 100 W was demonstrated in 1999 , and it illustrated that the advantages of Yb doped double cladding structure can support for further increase in the average power by scaling the size of the optical fiber and the power of pump diode source. Soon after that, the power of cladding pumped YDFL obtained the kilowatt level. Thereafter, by investigating the large-area core design a nd fabrication, the single-mode operation in kilowatt level was realized that would not have been possible for Nd doping. Figure 3: Absorption and emission cross sections of ytterbium-doped germanosilicate glass, as used in the cores of ytterbium-doped fibers. Another sophisticated technique which is adopted in all double-clad fiber lasers at 3 kW and above, is tandem-pump [in-band pumping with high-brightness pump sources, such as one or several fiber lasers, or thin disk laser]. The tandem pump makes it possible to pump close to the emission wavelength so that the quantum defect heating will be low resulting in a reduced thermal load. Actually, some advanced solid-state lasers, such as thin disk laser, is well matched with requirements of in-band high brightness pumping source, and 1 KW level output thin disk laser pumped fiber laser have been realized. Nonlinearities are an issue to further increase the CW output power of the fiber laser. The fiber laser considered above such as in Fig. 1 has operated with linewidths in the 110 nm range. In such system with cw operating, excepting at the extremely high powers or long delivery fibers, the stimulated Raman scattering (SRS) is a weak effect and is relatively easy to prevent. However, for output power above 10 kW, the Raman gain can become so high (tens of decibels) that a considerable part of the power is transferred to a longer-wavelength Stokes wave, reducing the power in the signal wavelength. There are some applications need single frequency sources which can provide light power with narrower spectral line width, such as coherent beam combination of multiple single frequency fiber sources with high power. This scheme offers a promising method for further power scaling, and consequently this stimulates interest in single-frequency power scaling. For narrow bandwidth, especially at linewidths less than 10 MHz, the SBS is the dominate nonlinearity and the severe obstacle for high power single-frequency fiber sources. The SBS can be suppressed with shorter fiber and larger mode field area, and output power of hundred watts has been reported with such schemes .However, this power is still less comparing with the bulk solid state laser. There are several options for SBS mitigation, including straining the fiber in order to broaden the SBS gain bandwidth, and reducing overlap between the optical and acoustic fields. The highest power high-gain fiber amplifier can archive 1.7KW. It was realized by combination of the modest spectral broadening with phase modulation and the fiber with enlarged effective mode area. The most effective way to mitigate nonlinearities (excluding self-focusing) is to enlarge the effective mode area by optimizing geometry designs and material choices of fiber structure. Unlike the passive power delivery fiber, this task is more challenge for active fiber, as doping-induced refractive index changing, and thermal stability will be issues. A straightforward design approach to maintain pure single-mode operation is to increase the core diameter, with the NA reducing correspondingly. However, the downside is the waveguide effect gets weaker, and consequently light is easier lost from the core when the fiber is bent. More works on fiber designs for addressing these challenges are related to photonic crystal fibers techniques. It is possible to make single mode operation in a multi-mode supported fiber, by building up preferentially amplify, or attenuate for specific mode, while the mixing or coupling between modes should be controlled to minimum. There have been works focu sed on using differential gain by selective RE doping across the core , and differential-bend-loss by controlled bending of the fiber. The leakage channel and chirally coupled core fibers are designed to selectively couple propagation mode to high loss mode. The high order mode but not the fundamental mode is coupled to leaky mode, which will substantially be attenuated. The multifilament core and multicore fiber arrange filaments or cores in a two-dimensional array. There are evanescent-field coupling among cores, and the overall structure can exhibit single-mode guidance with large mode area. Academic Objectives From the aspect of power generation, Investigation of advanced fiber for mitigating nonlinearity will be still the most critical issue in increasing the output power for cw fiber lasers. It has been estimated that the maximum single core output powers of the ytterbium doped fiber laser should be at several tens of kilowatts level based on present technique. However, single-mode operation is not indispensable for lots of high power lasers applications. The single or near single mode operation in the MM fiber which is developed by balancing the mode quality, the achievable power, and the damage threshold of the fiber, can offer possibilities to archive higher output power. In addition to that, as the emission wavelength of well developed thin disk laser is still covered by the Yb ions absorption band and is more close to the emission band of the Yb ion, the research on novel architecture using thin disk laser to tandem pump the special designed Yb doped fiber laser also offers the pote ntial to increase output power of fiber laser and develop novel fiber laser with useful function. The proposed research will focus on advanced fiber, especially for the evanescent-field coupled waveguides, also called multi-core fibers (MCF). The main aim is to design and realize novel types of active MCF for increasing the output power of fiber laser with good beam quality, and for suppressing the SBS effect. Besides that, Based on the advanced thin-disk laser, and the novel MCF fiber, the investigation on the novel laser architectures will also be performed. The Outline of the Project According to the above proposed objectives, the research work can be divided to two main phases. The first phase will be focused on fiber design and fabrication, and the expected deliverable is the novel active fiber with improved performance in nonlinearity mitigation and bending resistant. The other phase is about the novel fiber laser architecture, and investigation of the novel tandem pump configuration based on thin-disk laser will be performed. Mathematical Model and Design Strategy The main nonlinearities for cw operating fiber laser is SRS and SBS. Although both of them can be mitigated by the enlarged mode area, the SBS is still too strong for increasing the power of single frequency laser in the LMA fiber. The proposed research aimed to suppress the SBS in the LMA fiber for mitigating both SRS and SBS. According to the previous research, the SBS threshold can be expressed by : (1) The ÃŽÂ ±u is acoustic attenuation coefficient for the acoustic mode of order u, Aeff is the optical effective mode area, G(Ñ ´max) is the SBS effective gain coefficient at the peak frequency, K is the polarization factor. We can see form the equation. Beside the mode area, the SBS can be suppressed by increasing the acoustic loss, reducing the overlap integral, and the SBS effective gain coefficient. The is the normalized overlap integral of the electric and acoustic fields and it can be expressed as : (2) The E0 is the optical field associated with the fundamental mode, and à ?u the field of a longitudinal acoustic eigen-mode of order u. The overlap integral can be changed by modifying the fiber refractive index profile and acoustic velocity profile. The acoustic loss can be changed by glass composition design. As different dopants have different effects on optical and acoustic properties, it is possible to create suitable dopants profile in the core and cladding to reducing the overlap integral or increasing the acoustic loss. Table 1 is some common dopants used for making silica glass based fibers. The profile of the optical and acoustic field can be indicated by optical and acoustic refractive indices. Similar to the optical refractive index, acoustic refractive index is defined as na(r) = VL Silica /VL (r) , where VL(r) is the longitudinal acoustic velocity in the core, and VL Silica is the longitudinal acoustic velocity of pure silica glass. Table 1. Trend of optical and acoustic refractive index change of different dopants in silica GeO2 P2O3 TiO2 B2O3 F2 Al2O3 Optical refractive index à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Å" à ¢Ã¢â‚¬  Ã¢â‚¬Å" à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ Acoustic refractive index à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Ëœ à ¢Ã¢â‚¬  Ã¢â‚¬Å" One straightforward approach to modify the loss for optical and acoustic field of a fiber structure is created a type of optical guiding and acoustic anti-guides with a dopant material(Fig 4 (a)), such as Al2O3, and it has been demonstrated in . The other approach is to reduce optical and acoustic field overlap, with different dopants in the core (Fig 4 (b)). The resultant optical and acoustic refractive index profiles of above approaches are shown below. (b) Fig. 4. Dopant designs for reducing the overlap of the optical and acoustic fields The strategies shown in fig 4 are based on single core fiber. There are quite a few research works on improving the effective mode field in single core fiber, and it is little room to enlarge the effective mode field areas further without detrimental effect in single core fiber LMA. Recently, multicore fiber based LMA has been investigated as passive delivery fiber , and as active fiber in the novel laser architecture. The supported optical mode field of MCF can be designed by core size and core interval; the profile of the acoustic and optical field can be modified by the distribution of dopants and doping area size; and the loss of the optical and acoustic can be controlled by doping material. Thus, it is worth investigating a novel active MCF supporting a few modes or only single supermode with the reduced overlap between the acoustic and optical field. Optical Index Al Yb Ge F/B Acoustic Index Fig 5 the schematic of the proposed 19 core double cladding fiber A fiber design strategy to suppress the SBS is shown in Fig 5. An optical guide while acts as an acoustic anti-guide in the effective optical field areas of MCF will be fabricated by manipulating dopants in core and cladding, for example as shown in fig 5, by choosing Al2O3 in core and GeO2 in cladding. Because the fields of optical and acoustic are separated, the interaction between the optical and acoustic waves is weaker. Furthermore, the MCF will be designed to support a few modes or only one supermode, that benefits for manipulating refraction index to increase threshold of the SBS in the single mode MCF, as the à ¢Ã‹â€ Ã¢â‚¬  n=neffà ¢Ã‹â€ nclad of single mode MCF is larger than single mode single core fiber(SMF), for example, the index difference à ¢Ã‹â€ Ã¢â‚¬  n=neffà ¢Ã‹â€ nclad is 3.69ÃÆ'—10à ¢Ã‹â€ 4 in the case of the 19-core fiber reported in and only 1.60ÃÆ'—10à ¢Ã‹â€ 4 for the SMF, providing more room of à ¢Ã‹â€ Ã¢â‚¬  n for manipulating dopants. Finally, the reference value of parameters such as the diameter of each core, the core interval, and the doped areas of each core, will be archived by numerical calculation. Numerical Calculation The optical field in the waveguide can be solved by numerical calculation the Maxwell equations. Like the optical field, by numerical calculating the nonlinear acoustic equation, the acoustic field can be obtained. After that the SBS threshold can be calculated with equation (1), (2). From the nonlinear acoustic equation, we can obtain the equation that determines the longitudinal acoustic eigen-modes. The acoustic modes that contribute to the SBS associated with the optical fundamental mode have constant azimuth. Neglecting the damping factor, the radial distribution of such a mode can be expressed as: (3) The ÃŽÂ ©u is the acoustic frequency and the ÃŽÂ ²u is the propagation constant of the acoustic mode, VL(r) is the longitudinal acoustic velocity profile across the fiber. The wave equation for optical field in waveguide is derived from the general Maxwell and can be written as: (4) The EO is the optical field, ko=2p/l is the wave number of the optical field, and no(r) is the refraction index profile across the fiber. The optical mode is efficiently backscattered by the acoustic mode when the phase-match condition, ÃŽÂ ² = 2ÃŽÂ ²u, is fulfilled, where ÃŽÂ ² is the propagation constant of the optical field. The ÃŽÂ ² is determined by the optical wavelength ÃŽÂ », the effective refractive index no,eff, and it can be expressed as: ÃŽÂ ² =kono,eff=2pno,eff/l. Determined by the structure, the acoustic field in the proposed 19 core fiber is confined in the inter cladding, and the acoustic index can affect the confining effect. As the position of inter cladding is fixed, once the doping concentration is chosen, the acoustic field will be determined. The optical field in the MCF is determined by both the doping concentration and the geometry structure of the MCF. It is the geometry structure of the MCF provides the extra room to design the optical field with desired mode. The field of a longitudinal acoustic (à ?u) can be numerical calculated with finite-element method. beside the finite-element method, previous research has indicated the à ?u can be solved by utilizing the solver for optical scalar wave equation after defining a few new terms for acoustic wave. to numerical solve the equations (4), as numerical calculation by the finite element method is still valid when strong coupling exists between the different cores, the mode structure of the optical filed in the MCF is also calculated by finite-element method based on commercial available software such as Fimmwave or Comsol-Multiphysics. After knowing the à ?u and the EO, the can be calculated by taking the à ?u and E0 into equation (2). Finally, taking the into equation (1), the Pth of the designed fiber can be obtained. The theoretical M2 propagation factor can be computed with the method in. For a doping state, different Pth value and mode structures can be achieved for different geometry parameter, such as single core diameter and core interval. Optimizing the geometry parameter is necessary to get the high Pth value with good mode structures. Finally, repeatedly implementing above step for different doping condition, a series of optimized reference parameters can be obtained. The home institute IFSW has equipped the fiber manufacturing facility consisting of a modified chemical vapor deposition (MCVD) preform production lathe and the new commissioned drawing tower. The prototype of the proposed double-clad MFC fiber will be produced in the IFSW by the stack and draw technique. Investigation on the Laser Architectures The mode field mismatch and high operation power set the obstacles on employing the state of art fiber communication components in the high power laser architecture. Beside that some of critical components for high laser, such Bragg gratings in the LMA cores, large mode area pump coupler or combiner for high power diode are still in the initial stages. Above aspects cause the architecture for the exited high power laser is limited comparing with well developed communication band fiber laser. Most of the previous research on increasing the output power focused on developing the LMA fiber. As the difficulty of increasing the output power by enlarging the mode field is increasing continuously, it is time to consider improve the laser output from other aspect. The high brightness power scalable thin disk laser acting as the in-band pumping source can generate less quantum defect heat than 9ÃÆ'—ÃÆ'—nm laser diode, providing the potential to developing novel or improving existed laser structure by using components which are thermal damage or degradation sensitive. Thus there are rooms to increase the output power or improve the efficiency by developing the laser architecture with thin disk laser and special designed high power components. One of proposed architecture improvements is to replace the butt-coupled HR-mirror in the existed laser with the Bragg grating in the core of the double cladding fiber. Fig 6 (a) the butt-coupling mirror based laser architecture Fig 6 (b) the FBG based laser architecture FBG1,2 reflectors for the laser radiation; FBG3 reflectors for the pump light; The reflection rate of the FBG1 is around 99%, that of FBG2is around 50%. For the butt-coupled mirror based laser architecture (Fig 6 (a)), as the butt-coupled mirror will reflect both the pump light and the laser radiation on a very small area, the energy densities will be extremely high in core and cladding near the conjunct point. To withstand such high power densities, special material substrate such as the sapphire is needed to remove the heat very quickly. Even though, the core power density is still close to the damage threshold of the mirror coating. Furthermore, as the pump wavelength is closed to the laser radiation wavelength, to fabricate the dichroic mirror will be rather difficult. Although the Bragg grating inside the fiber core still has the problem of thermal damage, the damage threshold of FBG will be higher than mirror face. Considerable power increasing is expected for replaying mirror with the Bragg grating. From the aspect of fabrication, the wavelength of the Bragg grating is determined by the mask period and the refraction index of the fiber core, it will be easy to fabricate two FBG with spectrum interval larger than 4nm, which is enough to separate the in band pump light and laser radiation. Finally the FBG also can provide the facility to control the laser wavelength, and the laser output wavelength will be determined by the corresponded reflector. In fig 6 they are FBG1,2. Fig 7 the proposed hybrid laser architecture DMCF: doped multicore double cladding fiber, SMF: single-mode fiber, PMSF: polarization maintained single mode fiber ISO1: polarization dependent optical isolator, Amp: amplifier, DM: dichroic mirror, BS: beam splitter,Li (i = [1; 5]): plus lenses, FBG1: fiber Bragg grating for laser radiation, FBG2: fiber Bragg grating for pump light, PZT: Piezoelectric Ceramics Limited by components, many well developed communication fiber laser techniques such as wavelength tuning and polarization stabilizing cannot be projected to high power fiber laser area directly. A promising method to solve the problem is to develop hybrid architecture which employs a low power single mode fiber feedback loop to control the high power laser. By applying the advanced communication laser techniques in the single mode feedback loop, the high power fiber laser with wavelength tuning and polarization stabilizing can be realized. The proposed hybrid laser architecture with wavelength tuning and polarization stabilizing is shown in fig 7. The thin disk emitted pump light is coupled to the double cladding fiber with a dichroic mirror and a plus lens. The FBG in pump wavelength is employed in the far end of the active fiber. A small part of the emitted beam is reflected and coupled to the feedback loop whereas the most of power is coupled out from the laser cavity. The lens set (L4 to L6) constitutes a free-space imaging system for projecting the far field of the DMCF onto the input face of the SMF. Polarization independent optical isolators and circulator in the feedback loop determined the light traveling direction and eliminated the unwanted reflected light. Furthermore, the polarization independent optical isolator shapes the light to single polarization state, which will be persevered in the feedback loop by polarization maintained fiber. The FBG1 is fixed in a stretch preloaded piezoelectric ceramics, and the reflected wavelength can be tuned slightly by driving the PZT with Bi-directional signal. After passing th e feed pack fiber, the DMCF will amplify the seed laser radiation, and consequently power will be scaled and the polarization can be preserved.

Mental Disorders Essay -- science

Mental Disorders The term mental disorder means psycological and behavioral syndromes that deviate signicantly from those typical of human beings enjoying good mental health. All that mumbo jumbo means that a person with a mental disorder was a few cards short of a full deck. This is probably not the persons fault that they are like this they were just born this way. These people are not all a like. They are not even in exact classes because all of the classes have not been seperated yet. In most cases a normal person that has no disorders is afraid of these type of people. This is because they do not want to turn out the way these people are. A common example of a mental disorder is down syndrome. There was a television program in the early 90's that featured a boy that had to live with this terrifying disorder. This show was very inspirational for all people with disorders. The boy's name was Corky who fought all aspects of the disorder. Them being from physical triumphs to just everyday kids harrassing him at school. The show was taken off the air in 1993 because of sponsers. Records of types of disorders are unknown along with many of other records of treatments to people inflicted with a disorder. This is mainly because in the early 1900's people thought that people with disorders were just stupid and they did not investigate further into the matter. The quanity of people that have a disorder is unknown. There is an estimated guess that 15% of the U.S. population has some sort of disorder but that is not factual. This is because the survey people only can estimate from the people who check theirselves into a institution, the ones who do so make up 3% of the 15% estimation. The U.S. in 1990 spent an estimated 148 billion on treating mental diorders. Childhood Disorders Several Mental disorders are evident first in infancy, childhood, and adolescence. Mental retardation is characterized by the inability to learn normally and to become as an independent and socially responsible as others of the same age in the same culture. A retarded person go through a lot of emotional problems because of the society making fun of these people. A retarded person has an IQ of less than 70. Attention-deficit hyperactivity disorder includes conditions marked by inappropiate lack of attention, by impulsiveness, and by hyperactivity, in which the child ... ...son go through a lot of emotional problems because of the society making fun of these people. A retarded person has an IQ of less than 70. Attention-deficit hyperactivity disorder includes conditions marked by inappropiate lack of attention, by impulsiveness, and by hyperactivity, in which the child has difficulty organizing and completing work, is unable to stick to activities or follow directions, and is excessively restless. Anxiety disorder include fear of leaving home and parents, excessive shrinking from contact with strangers, and excessive, unfocused worrying and fearful behavior. Persuasive developement disorders are characterized by distortions in several psychological functions, such as attention, perception, reality testing, and motor movement. An example is infantile autism, a condition marked by unresponsiveness to other people, bizarre responses, and gross inability to communicate to the others in the world. Paranoid Disorder The central feature of the paranoid disorders in a persons dilusion, for instance that he or she is being persecuted or conspored against. In other form, the dilusion consists of unreasonsably jealousy. the person maybe r

Iranian Revolution and Persepolis Booklet Conventions Essay

High and Low cultures are terms given to value the quality of the text. Low culture text is usually the text written for entertainment and pleasure and does not encourage complex reflection and thoughts . Comics are considered as a Low culture and comics and graphic novel are similar to each other but graphic novel are not considered to be Low culture. High culture text is written to encourage complex reflection and thought. High culture are usually full of literary features while low culture has low literary features. Text with high culture also called privileged text and text with low culture is called marginalized . 2- Everyone has his own way of thinking, if three people read a book they will think differently and will have different opinions about it that’s why we respond to the text is shaped by our ideology because everyone understand it from a different perspective. The same thing happens when different people read a graphic novel , they all have different opinions and ideas and they discuss it some people may change their opinions after they heard someone’s else opinion ,that’s how it changes our beliefs, attitudes and values toward literature 3- Symbols in a Graphic novel are easy to understand cause most of the are colours , body language , objects and clothing etc.. .In Persepolis Satrapi has made it different than any other graphic novels , she made no colours only black and white and this is a symbol of something that happened in the past . 4- Satrapi choose to write Persepolis in form of a graphic novel to tell her story ,because she want us to understand what she understands .She is writing her story so she wants us to feel how it feels to grow up during a revolution and a war , and how it feels to move from your country to a different one having a new life she wants us to feel what she felt and she actually succeeded at it Style and Literary Traditions: Persepolis is more bildungsroman than a memoir, because Satrapi didn’t only want to tell the story of her childhood but she wanted to show the way she lived in Iran at the time of the Islamic revolution, also she wanted to show how she grew morally, socially and spiritually making herself an example of how a young girls grew up at this time and bildungsroman is when protagonist must progress from childhood to adulthood, leave home to undergo a journey, and develop a more mature understanding of his or her self. Satrapi also shows how is feels for a young girl to grow up during a Revolution and live in Iran while it was at war with Iraq, those young girls saw communists getting shot and killed by the shah army and hearing stories about political prisoners being tortured during the revolution and saw planes blowing up buildings and other events too. Although it was horrible but Satrapi use a satirical tone sometimes when talking to the revolution guardians Literary Features: Satrapi has been able to manipulate the literary features well though it is a graphic novel which sometimes authors find it hard to use the literary features. Satrapi has used alot of symbols and one of the most important symbol was â€Å" the veil â€Å" which shows the rebellious side of Satrapi and that she was against wearing it but the Islamic government said it is obligatory for women and girls to wear veil. She has also been hyperbole about it Satrapi has used many allusions; most of them are people some are rebellious figures like : Che Guevara, Fidel Castro , they symbolize how a young generation is forced to become revolutionary even though they know little about the turmoil they fight , most of the allusion are about being rebellion and the war. Unlike other writers, Marjane Satrapi has it a little easier because she is able to literally show us what she wants us to see , and the Major thing about persepolis is that it has no colours it’s all black and white to give the story a more ancient feel, she wants us to see that all of this has already occurred. Moreover, the simplicity of her images allows her to demonstrate that this time in her life was not a great one, and that most of it is blurry. Perhaps the lack of color also signifies how somber that time was. Furthermore, she usually draws herself in the background, this shows how inferior she unworthy of being at the same level of men. As she gets older in the novel, she starts to show herself more, it is almost as if she is starting to believe that she is finally getting to the level of men. She begins to talk more to people, and not only speaks her thoughts to herself. Themes: Any young woman growing up is going to face struggles especially during her adolescence. However, to grow up in the midst of the Iranian revolution is undoubtedly a life changing experience. In a society where one certain religion is forced upon you, and where you go, what you wear, who you see, and all that you do is restricted, it is clearly difficult to accept. Especially to a determined and independent young lady such as Marjane Satrapi. In Persepolis one of the most important themes of the novel is government and society and its role in determining the sequence of events that Satrapi’s life takes on such as in the first chapter veils are forced on the women of Iran. In Persepolis Satrapi has used many themes and as mentioned one of the most important themes is government and society. The Iranian society after the revolution was forced to do what their government tells them like wearing the veil and this is also connected to the theocracy and dictatorship theme that the Islamic government turned into a dictatorship , dictatorship was not only with the government but also in Satrapi’s house she calls her mother a â€Å" the dictator †¦ guardian of the revolution of the house The government played a big role in 1980’s Iran by implementing new laws and restricting old freedoms, whoever does obey is either sent to jail and tortured or being executed and a lot of people where being executed for doing things forbidden by Islam ,the government used Islam as a cover to do whatever they want without people questioning them. Even though the Islamic government prevented partying and drinking, people went to illegal parties and drank wine this is considered as an act of rebellion which is also a theme. Rebellion is also a major theme in Persepolis, rebellion is not only against a government it can also be rebellion to what people say. Satrapi uses cigarettes as a symbol of rebellion, she want to show that she can do whatever men can do because at this time in Iran there were feminism. Moreover , Satrapi uses more rebellion figures to support her rebellion theme like Che Guevara, Fidel Castro and Trotsky they are a symbol for freedom Iran was in an outer war with Iraq and internal war against Iranians. Those are the best words that could describe what is happening inside Iran in that time, the army was fight the Iraq’s and was also killing communists and people that have a secular thoughts. Although, the kids of the lower class are sent to war to fight for their country, but before they are sent, they are given this golden key which sybolizes the riches and wealth they will have if they go into war for their country. Not having much, these kids end up joining the army being promised these dreams that never happen. While on the other hand the higher classes are partying and enjoying themselves, not doing anything to protect their country, but only themselves. Isn’t that sad. Also in the case of Marjane her maid doesn’t sit with her and her parents had a cadillac showing that they were wealthy, but Marjane didn’ like the idea of that. If you are a powerful person that has a lot of money, or if you were a king, you were part of the high class people. If you are poor or a peasant, you are considered to be in the lower class. What also exists is a middle class who refers to those who can make enough money to dress properly and own certain things that peasants can’t. Being a part of the middle class doesn’t make you a high class person because you don’t have power and don’t have a fortune, but it’s enough for good living Martyrdom was also a major theme in Persepolis since the war started and Satrapi describes it â€Å"To die a martyr is to inject blood into the veins of society.† Marjane reflects that the regime depends on the war to retain its political control of the country. A million people lose their lives in the war. The regime becomes more repressive and seeks to stop â€Å"the enemy within† by arresting and executing those that defy its rule. Heroism is also a theme which is connected to Persepolis where Satrapi symbolizes the political prisoners that were tortured and executed as heroes and when she found out that her uncle Anoosh was tortured too ,she thought of him as a hero At this time in Iran the social classes was also a major theme in the novel mostly all social classes were unequal and this wasn’t fair to Marjane at some points. She comes to learn that if you are not in the same social class as someone else, you are not able to marry them. Also, higher social classes were treated better and were paid more attention to, other than the lower class people. There was a specific part of the book where some kids asked Marjane if she had any â€Å"star wars† toys, and she didn’t. All little Marjane had were some boring books to offer them. Persepolis is very powerful and informative. It showed the history of Iran’s civil war and revolution and the fall of the Shah. When someone would say the word â€Å"Iran† people would think of oil, criminals, and communist. they never knew that they would be able to relate Iran to family, love, peace, hope, Michael Jackson. It has definitely given a new meaning behind the word â€Å"Iran.† It has also given a new outlook of the people of Iran.

Samuel Sewall and William Byrd II essays

Samuel Sewall and William Byrd II essays The most important period or time of life for Samuel Sewall and William Byrd II is during the age forty to fifty for each mans life. It is at this time that each man makes his largest influential mark in history. For Sewall the time period from which I will taking most of my information is 1692, it is at this time that Sewall becomes a judge and takes part in the Salem witch trials. For Byrd I will be using information from 1714, it is at this time that Byrd is fighting with England and trying to become a governor. The themes of which I will be writing are comparing and contrasting the activities of each man, what each did as an occupation and the major contributions of each man to society. Samuel Sewall was born at Bishop Stoke in Hampshire, England on March 28, 1652. In 1661, Sewall came with his family to settle in Newbury, Massachusetts. At the age of 15 he was excepted into Harvard. Sewall married Hannah Hull, the daughter of one of the wealthiest men in the colony in 1676 and began a career as a merchant. In 1681 Sewall was appointed by the General Council to run a Boston printing press. Sewall used his position to publish articles of his own and achieve greater notoriety. From 1691 to 1725 Sewall served on the Governor's Council. Governor Phips appointed Sewall to the Court of Oyer and Terminer on May 27, 1692. Sewell's diary provides important information about the Salem witch trials. It is these trials for which Sewall is most famously known.# The diary entries reveal little personal reservations or remorse concerning his own role in the conduct of the trials. In December 1696, however, Sewall wrote a proclamation for a day of fast and penance and reparation by the government for the sins of the witchcraft trials. Sewall publicly apologized for his role in the trials. Each year after 1697 Sewall set aside a day in which he fasted and prayed for forgiveness for his sins in the Salem trials. Though his role in the Salem...

Comparing Grace Nichols to William Carlos Williams †Literature Term Paper

Comparing Grace Nichols to William Carlos Williams – Literature Term Paper Free Online Research Papers Comparing Grace Nichols to William Carlos Williams Literature Term Paper Grace Nichols, a compromised writter with the richness of Pre-Columbian cultures, has attempted with her work along her life, to avert the imposed ideas from western societies. On the other hand, the William Carlos Williams’ work turns around the everyday circumstances of life and the lives of common people. In addition, the Williams’ poetry experiments with innovative techniques of meter and lineation. Both features are present in the poems that we going to analyze in this essay. Beginning with the poem analysis, we can start to speak about the deviation. It would be more evident in â€Å"A poor old woman†; however, it’s present in both poems. In the Williams’ poem, we can see a semantic deviation like the enjambment in each stanza. An example of that can be the first one:† munching a plum on/ the street a paper bag / of them in her hand†. With regard to the look of the poem, we can find a lot of alterations in the discourse pattern, like the deviate use of punctuation, capital and lower-case letters and the different size of the stanzas. For example, the first stanza contains three lines, whereas the rest contain four lines. As for the defamiliarization on â€Å"The Fat Black Woman Goes Shopping†, we can find different kinds of semantic deviations. On the one hand, we can see enjambments in this poem too, as in the last stanza: â€Å"The fat black woman could only conclude / that when it come to fashion / the choice is lean†. On the other hand, we can observe a rich imagery in the poem. For instance, the second stanza cold be a symbol of the society rejection towards the appearance of the protagonist of the poem: â€Å"Look at the frozen thin mannequins / fixing her with grin / and the pretty face salesgals / exchanging slimming glances / thinking she don’t notice†. In addition, we can see a simile in the fourth stanza, when the author says: â€Å"Nothing soft and bright and billowing / to flow like breezy sunlight / when she walking†. At the same time, we can find a metaphor in these lines, because Nichols establishes an implicit comparison between the ideal pomp of th e fat black woman and a â€Å"breezy sunlight†. Moreover, also the poem contains deviation with regard of the look of the poem, for example in the size of the stanzas and the lines or in the use of the capital letters in the poem’s title. With regard to the register, Williams uses in his poem a neutral tone. He is only showing a real fact, without adopt any special attitude as the critic or the sarcasm. Moreover, the vocabulary used isn’t too much poetic or cultured, but plain and colloquial. On the other hand, in the Nichols’ poem the tone is critical, because she is denouncing the slavery of fashion and the perfect bodies in western societies. In addition, she uses a plain vocabulary along the poem. As for the poetic voice, its approach is similar in the both poems. They have an external voice that is talking about the life of a woman. However, whereas in â€Å"To a poor old woman† the poetic voice only explains the facts, in â€Å"The Fat Black Woman Goes Shopping† the poetic voice is being critical with this situation. Talking about the parallelisms, in â€Å"To a poor old woman† we can see a phonological parallelism: an alliteration with the sound of the letter â€Å"h†; for instance, in the two last lines of the second stanza: â€Å"to the one half / sucked out in her hand†, although this alliteration is repeated along the poem. On the Nichols’ poem, we can find two anaphors: in the fourth and the last stanzas with the word â€Å"Nothing† and in the fifth and sixth stanzas with the words â€Å"The fat black woman†. As for the repetitions, in Williams’ poem we can see a clear epizeuxis in the second stanza with the sentence: â€Å"They taste good her†. At the same time this is a ploce, because the sentence is repeated in the last line of the poem too. Moreover, we can find another ploce with the word â€Å"her†, which is repeated along the poem; however, this is a normal thing because the author is talking about a woman. In the Grace Nichols’ poem there are a ploce in the last line of the fifth stanza: â€Å"journeying and journeying†. About the ellipsis we can say that isn’t evident in â€Å"The Fat Woman Goes Shopping† but that in â€Å"To a poor old woman† we can see an ellipsis in the first stanza: â€Å"munching a plum / on the street â€Å"AND† a paper bag†¦Ã¢â‚¬ . Finally, with regard to the sound patterns, we can emphasize that both poem haven’t a constant rhyme. This way, with these two poems, William Carlos Williams and Grace Nichols show the lives of two different women, from different points of views, but coinciding in the fact that these two lives aren’t too much happy and beautiful. Research Papers on Comparing Grace Nichols to William Carlos Williams' - Literature Term PaperHonest Iagos Truth through DeceptionWhere Wild and West MeetIncorporating Risk and Uncertainty Factor in CapitalMarketing of Lifeboy Soap A Unilever ProductResearch Process Part OneHip-Hop is Art19 Century Society: A Deeply Divided EraThree Concepts of PsychodynamicComparison: Letter from Birmingham and CritoBringing Democracy to Africa

Air Carrier Safety; History, Statistics, and Forecast Essay

Air Carrier Safety; History, Statistics, and Forecast - Essay Example The first laws that deal with commercial aviation were passed during the 1920’s. One specific act that was critical in the development of the aircraft safety is the Air Commerce Act of 1926 (McDougall, 2007). This act required pilots and aircraft to be examined and licensed for accidents and crashes to be sufficiently investigated. Moreover the establishment of safety rules and navigation aids were established under the Aeronautics Branch of the Department of Commerce. Given these advancements in the policy arena, over the course of 1926 and 1927, there were a total of 24 dangerously fatal commercial airline accidents (Bamber, 2009). Furthermore, the following 2 years resulted in a total of 67 accidents which is a record in terms of the worst period of time for accidents in aviation history. The calculated accident rate was about 1 for every 1,000,000 miles flown. If converted to the current rates of travel, such numbers would translate into 7,000 fatal incidents per year (McD ougall, 2007). Though 1927 is the most fatal year in terms of airline travel, ever since that year, the number of annual accidents have steadily declined. Furthermore, after 1997 the number total number of fatal airline accidents dropped less than .2 percent of its previous rate with less than 1 for every 2 billion miles flown per person. Consequentially air travel has become one of the most safe methods of travel. It seems as if most accidents are not caused by human error but rather by external conditions that effect travel such as weather (Bamber, 2009). This is empirically proven by the fact that a disproportionate number of all U.S. aircraft crashes occur in Alaska, largely as a result of severe weather conditions. Between 1990-2006 there were 1441 commuter and air taxi crashes in the U.S. of which 373 (26%) were fatal, resulting in 1063 deaths (142 occupational pilot deaths). Alaska accounted for 513 (36%) of the total U.S.

Drug Control Essay Example | Topics and Well Written Essays - 1500 words

Drug Control - Essay Example But even in these new types of programs, the harmful status of marijuana continues to be diminished as it is becomes more commonly recognized among both youths and their parents that marijuana poses at most the no more of physical, psychological and social threat as hard drugs. However, harder drugs such as methamphetamines and cocaine are a different issue and should be viewed as such. All available resources should be used to keep these drugs out of the hands of teenagers, the most vulnerable group because they are easily influenced and suffer a greater potential for lifelong damage. Perhaps a more reasonable approach such as the decimalization of the soft drug marijuana and tighter controls on more dangerous substances should be considered. The teenage years are the time period when people transition from naive children to socially knowledgeable adults. During this part of life, most persons have feelings of insecurity because they are developing at a swift pace both physically an d psychologically. A teens need to belong within a group is powerful during this period and, along with the fact that they do not yet have the decision-making judgment of adults, often leads to bad choices including choosing to use hard drugs. Teenagers are naturally inquisitive, one of the justifications given for this age group experimenting with drugs. They also are inclined to become bored easily and experience recurrent emotional highs and lows, all probable factors in teenage drug use. Hard drug use increases the chance that teenagers will contract a social disease, become pregnant, perform inadequately in school and attempt suicide as this paper will examine. Adolescents are in a more vulnerable life circumstance than are adults because teens are still developing in every facet of their lives. Regrettably, it is this same group that has the most access to drugs as schools have become prolific illegal drug stores. Statistics collected by the National Institute on Drug Abuse de monstrate that schoolchildren have easy access to drugs and alcohol. â€Å"The average age of first alcohol use is 12 and the average age of first drug use is 13. Almost two-thirds of all American young people try illicit drugs before they finish high school† (Anderson, 1996) The relationship between hard drug use among teens and an increased occurrence of sexual activity is a broadly accepted reality by both researchers and the general public. Many studies have time and again demonstrated an association between unsafe sexual behavior and drug use by teenagers. Drug users are more prone to take risks than do teens that don’t use drugs. This may be an obvious assertion but a tendency to take unnecessary chances with their health combined with a lowering of inhibitions while on drugs and the inherent need of all teens to feel accepted by their peer group leads to increased sexual activity. This problematic circumstance also enhances the chance of teens having multiple se xual partners, having sex at an earlier age and decreases the odds that they will utilize contraception than those that do not use marijuana. â€Å"Teens 15 and older who use drugs are five times more likely to have sex than are those teens who do not use drugs and teens who have used drugs are four times more likely to have been pregnant or to have gotten someone pregnant than teens who have never† (The National Center on Addiction and Substance Abuse, 1997). Teenagers are more emotionally unstable younger children and adults