Tinnitus And The Psychology Of Hearing Essay Example for Free

Tinnitus And The Psychology Of Hearing Essay â€Å"Tinnitus is the subjective sensation of noise—usually described as ringing, hissing, buzzing, roaring, chirping, or clicking sounds—in the ears that cannot be attributed to any external sound† (Hannan, Sami, Wareing, 2005; Lalwani, Snow, 2005). The American Tinnitus Association (2007) estimates that about 50 million Americans experience tinnitus, with men affected more than women (Lockwood, Salvi, Burkard, 2002). â€Å"Twenty-five percent of these individuals suffer from severe enough tinnitus to prompt medical consultation†. Although a relatively common condition, the mechanisms of tinnitus are as yet poorly understood (Lalwani et al, 2005; Lockwood et al, 2002). â€Å"As discussed by Lockwood and associates (2002), there are currently two schools of thought that offer contradictory explanations as to the origin of tinnitus†. On the one hand are those who forward the hypothesis that tinnitus is mainly due to a cochlear pathology, as evidenced by the high incidence of cochlear damage in individuals with tinnitus. This is countered on the other hand by those who propose a central nervous system origin of tinnitus, as implied by the observation of tinnitus in patients with complete transections of the auditory nerve (Lockwood et al, 2002). The present paper is a review of the physiology of hearing, and an attempt to correlate it with tinnitus. Hearing is a function subserved peripherally by the ears and the auditory nerve (cranial nerve VIII), and centrally by the transverse temporal gyri of the temporal lobe (Willis, 2004). These structures altogether make up the auditory system, which primarily functions in the transduction of sounds emanating from the environment. The peripheral auditory apparatus—that is, the ear—â€Å"acts as the interface between the external environment and the individual†. Sound—actually wave vibrations—enters the external auditory canal and sets the tympanic membrane in motion. This, in turn, moves the ossicles—the maleus, incus and stapes—which causes pressure changes in the fluid-filled inner ear. Clearly, from the external environment to the inner ear, sound is carried as wave vibrations, transmitted initially through solids—cartilage and bone—and later through a fluid media—the perilymph and endolymph. The efficiency of this process—a transfer of energy from air, through solids, then through fluids—is ensured by the tympanic membrane and the ossicles, which act as an impedance-matching device (Lalwani et al, 2005). From the internal ear to the central nervous system, on the other hand, sound is interpreted as gradients of electron charges across membranes. The inner ear—principally the cochlea—is a complex composed of the bony and membranous labyrinths. The bony labyrinth component of the cochlea includes several chambers, namely the scala vestibuli and the scala tympani. The scala vestibuli connects with the vestibule and the oval window, whereas the scala tympani connect with the round window. These two chambers merge at the helicotrema, located at the cochlear apex. The membranous labyrinth component of the cochlea is the scala media, which is located between the scala vestibuli and scala tympani. As mentioned previously, the inner ear is a fluid-filled structure. Specifically, the scala vestibuli and the scala tympani are filled with perilymph, which resemble cerebrospinal fluid, while the scala media is filled endolymph, which resembles intracellular fluid (Willis, 2004). Within the cochlea is located the organ of Corti, the neural apparatus responsible for sound transduction, which is composed of several thousand hair cells, the sensory receptors for sound. At the apex of each hair cell are stereocilia, and at the base are nerve fibers that belong to the cochlear division of the eighth cranial nerve. The sound wave transmitted by the middle ear case fluid movements within the bony labyrinth, and part of the hydraulic energy of these fluid movements result in displacement of the organ of Corti. The stereocilia are deformed or bent by the shear forces produced by this relative displacement. The current concept of cochlear transduction is that displacement of the tips of the stereocilia, especially if this displacement is toward the tallest cilium (Willis, 2004), allows potassium to flow into the cell, resulting in its depolarization (Lalwani et al, 2005; Ricci, Kachar, Gale, Van Netten, 2006). The influx of potassium opens calcium channels near the base of the cell, stimulating transmitter release, thought to be glutamate or aspartate (Willis, 2004; Lalwani et al, 2005; Ricci et al, 2006), and firing of the cochlear nerve fibers. This discharge is transmitted to, from peripheral to central, the dorsal and ventral cochlear nuclei, trapezoid body, superior olivary complex, lateral lemniscus, inferior colliculus, medial geniculate nucleus of the thalamus (which gives rise to the auditory radiation), and ends in the auditory cortex located in the transverse temporal gyri of the temporal lobe (Willis, 2004; Lalwani et al, 2005). The end-result of all these is the perception of sound. The subjective perception of sound that is tinnitus could theoretically originate anywhere along the length of the auditory system. However, since the sound heard of individuals suffering from tinnitus is not attributable to any external source, the origin of tinnitus could be limited to the cochlea, specifically the organ of Corti, and the central nervous sytem (Lockwood et al, 2005). Cochlear damage, specifically damage to the hair cells of the organ of Corti, was initially believed to cause tinnitus (Eggermont, 1990; Zenner Ernst, 1993). Although auditory receptor cells have been documented to regenerate and subsequently recover functionally after damage in many vertebrates (Goode, Carey, Fuchs, Rubel, 1999; Stone Rubel, 2000; Zakir Dickman, 2006), spontaneous regeneration of mammalian hair cells does not occur (Zakir et al, 2006). Damage to hair cells, especially through prolonged exposure to supraphysiologic sound levels, may result to transmission of depolarization within the hair cell, and, thus, false perception of sound in the absence of an external source of the same. In contrast to this proposition was the hypothesis forwarded by Lockwood and companions (2002), which attributes tinnitus to central nervous system defects. â€Å"They propose that hearing loss results to reorganization of the pathways in the central auditory system†, which lead to abnormal interactions between auditory and other central pathways, as is seen in neuropathic pain. An example of this phenomenon is gaze-evoked tinnitus, â€Å"where lateral eye movements fail to produce the inhibition of the auditory cortex observed in controls†. It was proposed that the absence of this phenomenon may contribute to the false perception of sounds, that is, tinnitus (Lockwood et al, 2002). It was contended that this explanation accounted for the perception of tinnitus in individuals whose auditory nerves have already been previously transected. Lockwood and associates (2002), citing from Levine (1999), also forwarded the explanation that tinnitus results from a reduction in auditory-nerve input, â€Å"which leads to disinhibition of the dorsal cochlear nucleus and an increase in spontaneous activity in the central auditory system†. This mechanism was proposed to explain tinnitus experienced by normal individuals following exposure to noise, or placement in total silence. REFERENCES American Tinnitus Association (2007). About tinnitus. Retrieved April 3, 2007, from http://www.ata.org/about_tinnitus/consumer/faq.html#1. Eggermont JJ (1990). On the pathophysiology of tinnitus: a review and a peripheral model. Hear Res, 48, 111-24. Goode CT, Carey JP, Fuchs AF, Rubel EW (1999 March). Recovery of the vestibulocolic reflex after aminoglycoside ototoxicity in domestic chickens. J Neurophysiol, 81(3), 1025-35. Hannan SA, Sami F, Wareing MJ (2005, 29 January). 10-minute consultation: tinnitus. BMJ, 330, 237. Lalwani AK, Snow JB (2005). Disorders of smell, taste, and hearing. In DL Kasper, E Braunwald, AS Fauci, SL Hauser, DL Longo, JL Jameson (Eds.), Harrison’s Principles of Internal Medicine (16th ed.) (pp.176-185). New York: McGraw-Hill Medical Publishing Division. Levine RA (1999). Somatic (craniocervical) tinnitus and the dorsal cochlear nucleus hypothesis. Am J Otolaryngol, 20, 351-62. Lockwood AH, Salvi RJ, Burkard RF (2002, 19 September). Current concepts: tinnitus. N Engl J Med, 347(12), 904-910. Radeloff A, Smolders JW (2006, May). Brain-derived neurotrophic factor treatment does not improve functional recovery after hair cell regeneration in the pigeon. Acta Otolaryngol, 126(5), 452-9. Ricci AJ, Kachar B, Gale J, Van Netten SM (2006). Mechano-electrical transduction: new insights into old ideas. J Membr Biol, 209(2-3), 71-88. Smith ME, Coffin AB, Miller DL, Popper AN (2006, November). Anatomical and functional recovery of the goldfish (Carassius auratus) ear following noise exposure. J Exp Biol, 209(Pt 21), 4193-202. Stone JS, Rubel EW (2000, 24 October). Cellular studies of auditory hair cell regeneration in birds. Proc Natl Acad Sci U S A, 97(22), 11714-21. Willis WD (2004). The special senses. In RM Berne, MN Levy, BM Koeppen, BA Stanton (Eds.), Physiology (5th ed.) (pp. 118-154). Missouri: Mosby. Zakir M, Dickman JD (2006, 15 March). Regeneration of vestibular otolith afferents after ototoxic damage. J Neurosci, 26(11), 2881-93. Zenner HP, Ernst A (1993). Cochlear-motor, transduction and signal-transfer tinnitus: models for three types of cochlear tinnitus. Eur Arch Otorhinolaryngol, 249, 447-54.

Political Views Essay -- Politics Government Ideologies Essays

Political Views â€Å"Which political side are you on?† You probably heard this question before and said you really didn’t know. I really didn’t know what political side I was on before I did some research on the three major political philosophies; Liberalism, Libertarianism, and Conservative. The civic stance I agree with the most is the liberal’s point of view. Liberals protect; individual rights to choose, government programs like Medicaid and welfare that help the needy, and that sex education programs that teach safe sex and prevent teen pregnancy.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  The liberal philosophy is the one I agree with the most. Liberals believe that the federal government should protect individual liberties and promote the general welfare. Contemporary liberalism is rooted in the Declaration of Independence as well as social and economic programs that began in the 1930’s and extended into the 1960’s. Today’s liberal tends to value individual rights and to be wary of restrictions on personal behavior. Equality is very important to liberals. Liberals believe that everyone should be treated equally. Liberals believe that the government shouldn’t control sex or religion, and that women have the right to choose. Liberals protect individual rights for many people and for women they included the right to choose, only a women knows what problems she has to face by bringing a child into this world. Government programs like Medicaid and Welfare afford people the simple rights to feed their...

Course Outline of Production Operation Management

ARID AGRICULTURE UNIVERSITY, RAWALPINDI MGT- 696 â€Å"Operations Management† BBA–6 (A & B Sections) Spring 2013 Visiting Faculty Member:M. Javed Akhtar Ex- General Manager Training, OPF Ex-Director Gneral, NAVTEC Head Office Prime Minister's Secretariat [email  protected] com Office Contact/Timings: 051-2541041 (direct), 0300-5338951(Cell) (0800 Hrs. to 1500 Hrs. ) Course Coordinator Mr. Irfanullah Munir The Prologue This three credit Hrs. course is designed for services and manufacturing sectors, basically, meant for defining the real meaning of the Operations Management in any given organization.The primary objective of the course is to provide the students with an understanding of the theories, models, problems, issues, and techniques related to the management of operations both in manufacturing and service sectors. This includes analyses of various tasks performed and decisions made by operation managers, both tactically and strategically. The operations function plays a vital role in achieving a company’s strategic plans. Since the operations function produces the goods and provides the services, it typically involves the greatest portion of the company mployees and is responsible for a large portion of the firm’s capital assets. It has a major impact on quality and is often the visible face of company with which the customer must deal. Customer service, product/service, quality issues, and the effectiveness of many customer interactions are all operations activities. In the face of increased international competition, Pakistani firms have lost market share and have not responded by working to improve both their operating efficiencies and the quality of their goods and services.With this renewed emphasis on operations, it has become increasingly important that students have an understanding of operations management and its significance to the success of the companies where they will work. To gain a competitive edge, Pakistani organizations need sound production/operations strategies. This is particularly true today, given the pressures of global competition and the need to satisfy ever more demanding customers. Operations functions appear as a powerful tool for achieving organizational objectives and strategies. Learning ObjectivesThe aim of this course is to provide a clear, well-structured and interesting treatment of Production/Operations Management as it applies to a variety of businesses and organizations. The course is intended to provide both a logical path through the activities of operations management and an understanding of the strategic context in which operations managers’ work. †¢ Strategic in its perspective of operations management’s contribution to the organization’s long-term success. We are unambiguous in treating the operation function as being at the center to most organization’s drive to improve their competitiveness. Conceptual in the way it explai ns the reasons why operations managers need to take decisions in each activity. Although some quantitative techniques are included, their primary aim is to illustrate the underlying principles of operation decisions. †¢ Comprehensive in its coverage of the significant ideas and issues which are relevant to most types of operations. †¢ Practical in the sense that the issues and difficulties in making operations management decisions in practice are discussed, and generally the treatment of topics reflects actual operations practice.This course is practical also that Case Exercise illustrating the approaches taken by actual companies are used to illustrate operations issues. Attendance Policy As you may all know very well by this time that the University (FUU) adheres to very strict attendance policy (i. e. minimum 75% mandatory attendance). As usual roll will be taken at the beginning of each class meeting. No one will be allowed to enter the classroom five minutes after the class starting time since it cause interruptions in the class activities. Professional conduct is expected throughout the course.Besides this, It is assumed that you have read all the policies and guidelines of the University regarding attendance, academic dishonesty, deadlines and so on and so forth Team Work There will be substantial Team work in this class. This is the need of today’s corporate world, and we have to learn how to pull our right slack while working in teams. Instructor as well as fellow team members, at end of the course, will evaluate each team member. Part of the grade of the team project(s) will be dependent on peer evaluations which is only for the developmental purposes and will be kept strictly confidential.Unannounced Quizzes There will be minimum four unannounced quizzes taken randomly throughout this course. Three best will be considered for grading. These quizzes will be handed out in the beginning of the class meetings and if you are late in clas s, you will miss that quiz. There are absolutely no make ups for these quizzes. Case Studies There may be cases assigned to groups and these cases will be resolved in team efforts. A short written report will be required along with the presentation of that case.Presenters will play the role of Management Consultants and the class will act as Board of Directors and will interact with the consultants at the end of the presentation to express their concerns and opinions. Term Project or Book Review You will be given case study or in lieu thereof book reviews relevant to the field of OM, Subject to availability of time. When awarded, details will be discussed in the class. Industrial Visit/Seminar An industrial visit and/or a seminar relating to the subject matter would be arranged. Grade Allocation and Breakdown |Weightage suggested by DBA |Weightage suggested by Teacher| |Unannounced quizzes/Book Review |10% |10% | |Assignment(s) / presentation / participation/discipline |15% |15% | | Midterm Examination |25% |25% | |Terminal / Final Examination |50% |50% | Course Contours and Schedule ? Current Academic Session 4th March 2013 onward ? Class Work32 Lectures (16 weeks) Teaching Time 48Hrs. 1st Week: ? Production and Operations Management: An Overview 2nd Week: ? Production System : Issues and Environment 3rd Week: ? Total Quality Management 4th Week: ? Need and Importance of Forecasting 5th Week: ? Qualitative Methods of Forecasting 6th Week: ? Quantitative Methods of Forecasting 7th week: ? Capacity Planning 8th Week: ? Facilities Planning ? Mid-term Examination 9th Week: ? Work System Design 10th Week: ? Managing Information for Operations System 11th Week: ? Aggregate Production Planning 12th Week: ? Just-in-Time (JIT) 13th Week: ? Scheduling & Sequencing 14th Week: ? Issues in Materials Management 15th Week: Independent & Dependent Demand Inventory System 16th Week: ? Total Productive Maintenance (TPM)/Computers in OM ** ? Final Examination (date to be announc ed later on) Recommended Readings Supplementary Readings | | IMPORTANT NOTE: ? The course outline is subject to change to a tune of about 10% if need arise. ? ** Subject to availability of time, the topics of â€Å"Advanced Manufacturing Systems† and â€Å"Computers in Operations Management† will also be covered. ———————– Issues in Production/ Operations Management Forecasting Operations System Design Planning & Scheduling Materials Planning Emerging Issues in OM**

Aryl Group Definition in Chemistry

An aryl group is a functional group derived from a simple aromatic ring compound where one hydrogen atom is removed from the ring. Usually, the aromatic ring is a hydrocarbon. The hydrocarbon name takes the -yl suffix, such as indolyl, thienyl, phenyl, etc. An aryl group is often simply called an aryl. In chemical structures, the presence of an aryl is indicated using the shorthand notation Ar. This is also the same as the symbol for the element argon but doesnt cause confusion because its used in the context of organic chemistry and because argon is a noble gas, and thus inert. The process of attaching an aryl group to a substituent is called arylation. Examples: The phenyl functional group (C6H5) is an aryl functional group derived from benzene. The napththyl group (C10H7) is the aryl group derived from naphthalene.