Unsere alltägliche Erfahrung ist mit verschiedenen akustischen Einfluessen wie Lärm, aber auch Musik verbunden. Jeder weiss, wie Lärm stören kann und Kommunikation behindert oder gar unterbindet. Ähnliche optische Effekte sind bekannt: starkes Schneetreiben oder Regengüsse verschlechtern die Sicht und lassen uns Umrisse nur noch schemenhaft erkennen. Jedoch koennen ähnliche Stimuli auch sehr positive Auswirkungen haben: Autofahrer fahren bei leiser Musik konzentrierter -- die Behauptung von Schulkindern, nur bei dröhnenden Bässen die Mathehausaufgaben richtig rechnen zu können, ist allerdings nicht wissenschaftlich erwiesen. Außerordentlich interessant aus dieser Sicht sind auch Reizleitungsprozesse: Reize werden nur weitergleitet, wenn die strukturlosen Signale der Neuronen mit ausreichend starker Intensität erfolgen, also ein Schwellwert überschritten ist. <br /> <br /> Der Physiker Dr. Alexei Zaikin von der Universität Potsdam beschäftigt sich mit sogenannten rauschinduzierten Phänomenen aus theorischer Sicht. Sein Forschungsgebiet sind Prozesse, bei denen Rauschen mehrfach das Systemverhalten beeinflusst: ist es ausreichend gross, d.h. größer als ein kritischer Wert, wird eine reguläre Struktur gebildet, die durch das immernoch vorhandene Rauschen mit der Struktur des Nachbarsystems synchronisiert. Um ein solches System mit kritischem Wert zu erhalten, bedarf es einer weiteren Rauschquelle. Herr Zaikin analysierte noch weitere Beispiele solcher doppelt stochastischen Effekte. Die Ausarbeitung derartiger theoretischer Grundlagen ist wichtig, da diese Prozesse in der Neurophysik, in technischen Kommunikationssystemen und in den Lebenswissenschaften eine Rolle spielen. / Our every-day experience is connected with different acoustical noise or music. Usually noise plays the role of nuisance in any communication and destroys any order in a system. Similar optical effects are known: strong snowing or raining decreases quality of a vision. In contrast to these situations noisy stimuli can also play a positive constructive role, e.g. a driver can be more concentrated in a presence of quiet music. Transmission processes in neural systems are of especial interest from this point of view: excitation or information will be transmitted only in the case if a signal overcomes a threshold.<br /> <br /> Dr. Alexei Zaikin from the Potsdam University studies noise-induced phenomena in nonlinear systems from a theoretical point of view. Especially he is interested in the processes, in which noise influences the behaviour of a system twice: if the intensity of noise is over a threshold, it induces some regular structure that will be synchronized with the behaviour of neighbour elements. To obtain such a system with a threshold one needs one more noise source. Dr. Zaikin has analyzed further examples of such doubly stochastic effects and developed a concept of these new phenomena. These theoretical findings are important, because such processes can play a crucial role in neurophysics, technical communication devices and living sciences.

No description available.

Thesis (M. Communication Pathology)--University of Pretoria, 2009. / Includes bibliographical references.

In this thesis, both experimental studies and numerical simulations of ultracold atoms in optical potentials are presented in a collection of nine scientific papers. In particular, noise-induced transport in dissipative optical lattices and superfluid properties of Bose-Einstein condensates have been studied. Noise is usually regarded as a complication to most systems and as something that needs to be minimized. However, in a series of experiments at Umeå University, noise has been shown to play a key role for laser-cooled cesium atoms trapped in dissipative optical lattices. By using a combination of two dissipative optical lattices, where the relative spatial phase between them can be controlled, a so-called Brownian motor can be realized, where energy can be extracted from the inherent noise. In the experiment, this energy is used to control the transport of the laser-cooled atoms in real time and along pre-designed paths. This thesis also presents a way to characterize this system in terms of energy conversion efficiency and coherence of the transport, which may allow for a more straightforward comparison with other systems that rely on noise rectification. In the studies, it is also shown that the noise triggers a downward drift due to gravity, even though the optical potential should support the atoms. Further investigation of this might help to understand the underlying principles of laser cooling, as well as showing that the system might be suitable as a flexible test bed for statistical physics. In close relation to the experimental system, two numerical simulations are also presented, one in which different ways to induce asymmetries between two periodic potentials are investigated, and one in which a proposal for detecting quantum walks is explored. In the second part of the thesis, a work from the Joint Quantum Institute is presented, where a long-lived persistent current in a toroidal Bose-Einstein condensate, held in an all-optical trap, is created. The critical velocity of the superflow is measured in the presence of a tunable barrier. The system can be seen as a first realization of an elementary closed-loop atom circuit. Finally a theoretical study of the crossover between one- and two-dimensional systems is presented, in particular the transition between a two-dimensional superfluid to a one-dimensional Mott insulator is investigated. / Medelst nio vetenskapliga artiklar presenteras i denna avhandling experimentella och teoretiska studier av ultrakalla atomer fångade i optiska potentialer. Framförallt har brusinducerade transporter och supraytande egenskaper hos Bose-Einstein-kondensat studerats.     För de flesta system betraktas brus som något negativt som bör minimeras, men i en serie experiment som redovisas i denna avhandling spelar bruset istället en avgörande positiv roll. I ett system där laserkylda atomer genom växelverkan med laserstrålar fångas i två individuella optiska kristallgitter, kan atomernas kollektiva rörelse styras genom att energi utvinns ur det inneboende bruset. I denna avhandling, genom att kontrollera de optiska potentialerna i realtid, visas att atomernas kollektiva rörelse kan styras längs förutbestämda banor med en så kallade Brownska motor. I ett annat experiment mäts verkningsgraden i omvandligen mellan brus och arbete, samt koherensen i atomtransporten. En sådan karakterisering gör att systemet blir enklare att jämföra med andra system som bygger på liknande principer. I avhandlingen presenteras också en studie där det visas att det inneboende bruset i systemet, tillsammans med en svag kraft, i detta fall från gravitation, kan skapa drifter trots att de optiska potentialerna borde vara tillräckligt djupa för att atomerna ska vara fångade. Denna upptäckt kan leda till ökad grundläggande kundskap om laserkylning. Dessutom visar det att systemet kan beskrivas med modeller från statistisk fysik. I relation till det experimentella systemet i Umeå redovisas även två teoretiska studier, en för två symmetriska periodiska potentialer och deras sätt att möjliggöra inducerade drifter med olika typ av asymmetrier, samt en annan för möjligheten att genomföra och detektera kvantvandringar.     I avhandlingen presenteras också ett experimentellt arbete utfört vid Joint Quantum Institute, där en långlivad ihållande ström i ett torusformat Bose-Einstein-kondensat har skapats i en optisk fälla. Den kritiska hastigheten på strömmen har mätts i närvaron av en ställbar optisk barriär. Detta system kan ses som en första realisation av en grundläggande atomkrets. Slutligen presenteras även en teoretisk studie av övergången mellan en- och tvådimensionella system, där fasövergången mellan superytande och Mottisolation studeras.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Thesis (M.A. (Communication Disorders))--Mahidol University, 1984.

Introdução: O zumbido é definido como uma sensação auditiva ilusória sem a presença de um som externo. Acomete homens e mulheres, mais comumente entre 40 e 70 anos de idade, às vezes podendo ocorrer em crianças. Análises de dados epidemiológicos indicam que a exposição ao ruído é uma das causas mais comuns de zumbido. Objetivos: Os objetivos gerais deste estudo foram verificar a prevalência do zumbido em trabalhadores expostos ao ruído ocupacional e avaliar a freqüência e a intensidade do zumbido. Os objetivos específicos foram avaliar a gravidade do zumbido; analisar a presença do zumbido por sexo, cor, idade e tempo de trabalho com exposição ao ruído e analisar a relação do zumbido com as freqüências mais acometidas na audiometria e com a presença e grau da perda auditiva, independente do nexo da perda. Materiais e Métodos: Trata-se de um estudo transversal para o qual foram selecionados 362 prontuários de trabalhadores expostos a ruído ocupacional ≥80dB(NA)/8h diárias. Estes trabalhadores haviam sido submetidos a meatoscopia, anamnese clínica e ocupacional, audiometria de via aérea, avaliação de freqüência e intensidade do zumbido e à escala de avaliação da gravidade do zumbido. Conclusão: A prevalência do zumbido foi de 9,9%. Nas análises de regressão conclui-se que trabalhadores com presença de perda auditiva em pelo menos um dos ouvidos têm 2,396 vezes mais chances de ter zumbido quando comparados com os que não tem perda auditiva. Os trabalhadores com faixa etária acima ou igual a 30 anos tem 5,353 vezes mais chances de ter perda auditiva em pelo menos um dos ouvidos quando comparados com os de faixa etária menor que 30 anos. Com relação ao tempo de trabalho em contato com o ruído, a analise estatística revela que trabalhadores com diferença de 1 ano no tempo de trabalho em contato com ruído tem um risco 5,3 % (OR=1,053) maior de apresentar perda auditiva. / Background: Tinnitus is an auditory phantom sensation experienced when no external sound is present. It occurs in both men and women, and is more prevalent between the age of 40 and 70; however, it may also occur in children. Analyses of epidemiologic data indicate that exposure to noise is its most common cause. Object: The aim of this study was to investigate the prevalence and characteristics of tinnitus in noise-exposed workers. Its specific objectives were to evaluate the severity of tinnitus, to compare the presence of tinnitus with the individual’s sex, race, age, and time of exposure to noise in the workplace, and to analyze the relation between tinnitus and the most affected frequencies in audiometric tests as well as the presence and level of hearing loss. Materials and Methods: The present was a cross-sectional study for which 362 files of workers exposed to noise (≥80dB(A)/8h per day) were selected. These workers had undergone otoscopy, clinical and occupational anamnesis, audiometric test of ear conduction, and an investigation of frequency, intensity, and severity of tinnitus. Conclusion: The prevalence of tinnitus found was 9.9%. After logistic regression analyses, it was concluded that workers with hearing loss in at least one ear have 2.396 times more chance of having tinnitus than those who do not have hearing loss. Workers aged 30 or older have 5.353 times more chance of having hearing loss in at least one ear than those younger than 30. As to time of exposure to noise in the workplace, statistical analysis showed that workers with a difference of 1 year in time of exposure to noise have a 5.3% (OR=1.053) higher risk of suffering hearing loss.

Millions of people across the world currently have noise induced hearing loss, and many are working in conditions with both continuous Gaussian and non-Gaussian noises that could affect their hearing. It was hypothesized that the energy of the noise was the cause of the hearing loss and did not depend on temporal pattern of a noise. This was referred to as the equal energy hypothesis. This hypothesis has been shown to have limitations though. This means that there is a difference in the types of noise a person receives to induce hearing loss and it is necessary to build a system that can easily mimic various conditions to conduct research. This study builds a system that can produce both non-Gaussian impulse/impact noises and continuous Gaussian noise. It was found that the peak sound pressure level of the system could reach well above the needed 120 dB level to represent acoustic trauma and could replicate well above the 85 dB A-weighted sound pressure level to produce conditions of gradual developing hearing loss. The system reached a maximum of 150 dB sound peak pressure level and a maximum of 133 dB A-weighted sound pressure level. Various parameters could easily be adjusted to control the sound, such as the high and low cutoff frequency to center the sound at 4 kHz. The system build can easily be adjusted to create numerous sound conditions and will hopefully be modified and improved in hopes of eventually being used for animal studies to lead to the creation of a method to treat or prevent noise induced hearing loss.

Submitted by GIOVANNA CESAR SILVA (lp_gi@hotmail.com) on 2016-01-29T14:02:29Z No. of bitstreams: 1 1Dissertação- Giovanna- Corrigida pós defesa REVISADO BIBLIOTECA.pdf: 1218313 bytes, checksum: 3a81f92de470a539200487ed220e181e (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-02-02T12:18:25Z (GMT) No. of bitstreams: 1 silva_gc_me_mar.pdf: 1218313 bytes, checksum: 3a81f92de470a539200487ed220e181e (MD5) / Made available in DSpace on 2016-02-02T12:18:25Z (GMT). No. of bitstreams: 1 silva_gc_me_mar.pdf: 1218313 bytes, checksum: 3a81f92de470a539200487ed220e181e (MD5) Previous issue date: 2016-01-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A exposição cotidiana ao ruído pode causar alterações auditivas. Os bombeiros são uma população de risco para essas alterações pois em seu cotidiano estão expostos a níveis elevados de pressão sonora. Implantar um Programa de Preservação Auditiva para esses profissionais é fundamental para promover sua saúde auditiva. Desta forma, o objetivo deste estudo foi avaliar o nível de conhecimento e atitudes de bombeiros em relação a audição e a eficácia de um programa de preservação auditiva para esses profissionais. Este foi um estudo prospectivo, comparativo, de coorte contemporânea com corte transversal. O mesmo foi realizado junto a prontidão do 10º grupamento do Corpo de Bombeiros. Compuseram a amostra 20 bombeiros que responderam o questionário em suas versões A e B e participaram do programa de preservação auditiva. A análise estatística foi realizada por meio do teste t-Student e da Correlação de Pearson. Adotou-se o nível de significância de 0,05. Ao analisar os resultados da versão A do questionário, observou-se que os profissionais apresentaram um bom nível de conhecimento a respeito da temática abordada e ao comparar os resultados apresentados nos questionários, versão A e B, aplicados antes e após o programa, verificou-se diferença estatisticamente significante para as questões 7 e 12, o que demonstrou mudança positiva no nível de informação após a participação desses profissionais nas ações educativas. A comparação entre os valores médios dos escores por área temática nos questionários, em suas versões A e B, demonstrou diferença significante para as áreas 2, 4 e 7. Os resultados deste estudo demonstraram que os bombeiros apresentaram um bom nível de conhecimento e atitudes em relação a prevenção de perdas auditivas e, a avaliação do programa mostrou mudanças significativas no conhecimento dos profissionais em algumas áreas temáticas. / Daily exposure to noise can cause hearing loss. Firefighters are a population at risk for these pathology, because in their daily lives, are exposed to high sound pressure levels. So implement a Hearing Conservation Program for these professionals is essential to promote their hearing health. Thus, the aim of this study was to evaluate the level of knowledge and attitudes of firefighters about hearing and the effectiveness of a hearing conservation program for these professionals. This was a prospective, comparative, cross-sectional cohort study. It was developed with professionals of readiness of the 10th Fire Department Company. The sample consisted of 20 firefighters who responded to a questionnaire, versions A and B, and took part of educational activities. Statistical analysis was performed using t-Student test and Pearson's correlation and a significance level of 0,05 was adopted. The analyses of the results of the questionnaire, version A, showed that the professionals had a good level of knowledge about the themes discussed. The comparison of the results presented in the questionnaires, version A and B, demonstrated statistically significant difference for questions 7 and 12, which showed a positive change in the level of information after their participation in educational activities. The association between the mean values of the scores by theme area in the questionnaires in their versions A and B, showed significant differences for the areas 2, 4 and 7. The results demonstrated that firefighters had a good level of knowledge and attitudes regarding hearing loss prevention, and the program evaluation showed significant changes in the knowledge of professionals in some theme areas.

Introdução: O zumbido é definido como uma sensação auditiva ilusória sem a presença de um som externo. Acomete homens e mulheres, mais comumente entre 40 e 70 anos de idade, às vezes podendo ocorrer em crianças. Análises de dados epidemiológicos indicam que a exposição ao ruído é uma das causas mais comuns de zumbido. Objetivos: Os objetivos gerais deste estudo foram verificar a prevalência do zumbido em trabalhadores expostos ao ruído ocupacional e avaliar a freqüência e a intensidade do zumbido. Os objetivos específicos foram avaliar a gravidade do zumbido; analisar a presença do zumbido por sexo, cor, idade e tempo de trabalho com exposição ao ruído e analisar a relação do zumbido com as freqüências mais acometidas na audiometria e com a presença e grau da perda auditiva, independente do nexo da perda. Materiais e Métodos: Trata-se de um estudo transversal para o qual foram selecionados 362 prontuários de trabalhadores expostos a ruído ocupacional ≥80dB(NA)/8h diárias. Estes trabalhadores haviam sido submetidos a meatoscopia, anamnese clínica e ocupacional, audiometria de via aérea, avaliação de freqüência e intensidade do zumbido e à escala de avaliação da gravidade do zumbido. Conclusão: A prevalência do zumbido foi de 9,9%. Nas análises de regressão conclui-se que trabalhadores com presença de perda auditiva em pelo menos um dos ouvidos têm 2,396 vezes mais chances de ter zumbido quando comparados com os que não tem perda auditiva. Os trabalhadores com faixa etária acima ou igual a 30 anos tem 5,353 vezes mais chances de ter perda auditiva em pelo menos um dos ouvidos quando comparados com os de faixa etária menor que 30 anos. Com relação ao tempo de trabalho em contato com o ruído, a analise estatística revela que trabalhadores com diferença de 1 ano no tempo de trabalho em contato com ruído tem um risco 5,3 % (OR=1,053) maior de apresentar perda auditiva. / Background: Tinnitus is an auditory phantom sensation experienced when no external sound is present. It occurs in both men and women, and is more prevalent between the age of 40 and 70; however, it may also occur in children. Analyses of epidemiologic data indicate that exposure to noise is its most common cause. Object: The aim of this study was to investigate the prevalence and characteristics of tinnitus in noise-exposed workers. Its specific objectives were to evaluate the severity of tinnitus, to compare the presence of tinnitus with the individual’s sex, race, age, and time of exposure to noise in the workplace, and to analyze the relation between tinnitus and the most affected frequencies in audiometric tests as well as the presence and level of hearing loss. Materials and Methods: The present was a cross-sectional study for which 362 files of workers exposed to noise (≥80dB(A)/8h per day) were selected. These workers had undergone otoscopy, clinical and occupational anamnesis, audiometric test of ear conduction, and an investigation of frequency, intensity, and severity of tinnitus. Conclusion: The prevalence of tinnitus found was 9.9%. After logistic regression analyses, it was concluded that workers with hearing loss in at least one ear have 2.396 times more chance of having tinnitus than those who do not have hearing loss. Workers aged 30 or older have 5.353 times more chance of having hearing loss in at least one ear than those younger than 30. As to time of exposure to noise in the workplace, statistical analysis showed that workers with a difference of 1 year in time of exposure to noise have a 5.3% (OR=1.053) higher risk of suffering hearing loss.