Cochlear implants (CIs) are prosthetic devices used to partially restore hearing for profound and severely deaf individuals. CIs convert sounds into electrical pulses which stimulate the auditory nerve fibers. An accurate model of auditory nerve fibers (ANFs) would help in improving the functionality of CIs. Previous studies have shown that the original Hodgkin-Huxley (1952) model (with kinetics adjusted for mammalian body temperature) may be better at describing nodes of Ranvier in ANFs than models for other mammalian axon types. However, the Hodgkin-Huxley model is still unable to explain a number of phenomena observed in auditory nerve responses to CI stimulation, such as short-term and long-term adaptation, the time-course of relative refractoriness, and stimulus-dependent random fluctuations in membrane threshold. Recent physiological investigations of spiral ganglion cells have shown the presence of a number of ion channel types not considered in the previous modelling studies, including low-threshold potassium (𝐼^KLT) channels and hyperpolarization-activated cation (𝐼^h) channels. In this thesis, inclusion of these ion channel types in a stochastic Hodgkin-Huxley model is investigated. Four versions of the model are formed and compared: that is, the standard Hodgkin-Huxley model, the standard model with /h only added, the standard model with 𝐼^KLT only added, and finally, the standard model with both h and 𝐼^KLT added. Two group of responses are explored: i) single-pulse responses and ii) pules-train responses. For the single pulse responses, a charge-balanced biphasic stimulus pulse is used. The effect of varying the pulse-width and the interphase gap is investigated for both leading phase polarities. Results are compared to responses for single monophasic stimulus pulses in some cases. Pulse-train responses are investigated for charge-balanced depolarizing-phase leading biphasic pulses at rates of 200, 800, and 2000 pulse/s. Results from single-pulse responses show an increase in spike threshold when one or both of these channel types are included. The addition of 𝐼^KLT increases random threshold fluctuations in the stochastic model, particularly for longer pulse widths. For pulse-train responses, rapid adaptation in spike rate may be resulting from 𝐼^KLT whereas 𝐼^h produces slower "short-term" adaptation. Thus, the simulation results suggest that including 𝐼^KLT and/or 𝐼^h in a Hodgkin-Huxley model improves the accuracy of the model in describing auditory nerve fiber responses during cochlear implant stimulation. / Thesis / Master of Applied Science (MASc)

Thesis (M.A.)--Texas State University-San Marcos, 2008. / Vita. Includes bibliographical references (leaves 72-75). Also available on microfilm.

No description available.

A Hodgkin-Huxley style system of ODEs was developed to model the ion channel activity of A. punctulata sperm flagellum during exposure to resact during chemotaxis. Empirical data was used in conjunction with parameter estimation methods in an attempt for the model to reproduce realistic Voltage potentials and ion concentrations. The change in calcium concentration is of particular interest, as it is essential in the waveform of the flagellum during chemotaxis.

Dissertation--Münster--Universität, 1999.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 233-241).

Thesis (M.A.)--University of West Florida, 2009. / Title from title page of source document. Document formatted into pages; contains 34 pages. Includes bibliographical references.

Thesis (M.A.)--Liberty University, 2009. / Includes bibliographical references.

Texte remanié de: Th.--English literature--New Haven--Yale university, 1964. / Bibliogr. p. 119-121. Index.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-16T10:30:57Z No. of bitstreams: 2 larissa_kretli_winkelstroter.pdf: 1482019 bytes, checksum: 9d2274173c5ed8fd73b659407d038396 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-16T10:32:26Z (GMT) No. of bitstreams: 2 larissa_kretli_winkelstroter.pdf: 1482019 bytes, checksum: 9d2274173c5ed8fd73b659407d038396 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-16T10:32:45Z (GMT) No. of bitstreams: 2 larissa_kretli_winkelstroter.pdf: 1482019 bytes, checksum: 9d2274173c5ed8fd73b659407d038396 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2015-01-16T10:32:45Z (GMT). No. of bitstreams: 2 larissa_kretli_winkelstroter.pdf: 1482019 bytes, checksum: 9d2274173c5ed8fd73b659407d038396 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2013 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Objetivou-se, com este trabalho, comparar o padr?o de crescimento de diferentes gen?tipos comerciais de frangos de corte. Foram utilizados 2.970 pintos de um dia, machos e f?meas sexados, provenientes de tr?s gen?tipos comerciais de frangos corte: Cobb, Hubbard e Ross, alimentados com tr?s n?veis nutricionais de amino?cidos. Para a determina??o das curvas de crescimento do peso corporal das aves, os dados foram coletados ao nascimento, aos 7, 14, 21, 28, 35, 42 e 49 dias de idade e foram avaliados a partir dos modelos n?o lineares: Brody, Gompertz, Log?stico, Richards e von Bertalanffy. Os crit?rios utilizados para escolha do modelo de melhor ajuste da curva de crescimento foram o coeficiente de determina??o, o desvio padr?o assint?tico, o desvio m?dio absoluto dos res?duos e o ?ndice assint?tico. Para estudar o crescimento alom?trico dos cortes, foram abatidas 36 aves, duas de cada tratamento, ao nascimento, aos 14, 28, 35, 42, 49 dias de idade, totalizando 216 aves, sendo avaliados os pesos da carca?a (PCA), peito (PP), coxas (PC), sobrecoxas (PSC), pernas (PPER) e asas (PA). Para o estudo do crescimento alom?trico da composi??o de carca?a, as mesmas foram trituradas, homogeneizadas e analisadas em duplicatas. Foram realizadas as an?lises de mat?ria seca (MS), prote?na bruta (PB), extrato et?reo (EE) e cinzas. O estudo do crescimento relativo dos cortes e composi??o da carca?a foi realizado mediante o modelo da equa??o alom?trica de Huxley. Dentre os modelos de curva de crescimento estudadas, as equa??es propostas por Gompertz, von Bertalanffy e Log?stico atingiram a converg?ncia, sendo que o modelo de Gompertz foi o mais adequado para descrever o crescimento das aves. De maneira geral, os machos apresentaram crescimento isog?nico dos cortes em estudo, quando comparado com o peso da carca?a. As f?meas, por sua vez, apresentaram crescimento heterog?nico negativo (b<1) para a maioria dos cortes em estudo. Para a composi??o da carca?a, o crescimento alom?trico foi isog?nico (b=1) para a deposi??o de prote?na bruta e cinzas, na maioria das an?lises. Os demais nutrientes apresentaram, de maneira geral, deposi??o precoce quando comparada ao peso da carca?a. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Zootecnia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT The objective of this work was to compare the growth pattern of different genotypes of broilers. We used 2,970 day-old chicks, sexed males and females from three genotypes of boilers: Cobb, Hubbard and Ross, fed with three levels of amino acids. To determine the growth curves of the body weight of the birds, the data were collected day-old, 7, 14, 21, 28, 35, 42 and 49 days of age and were evaluated from the nonlinear models: Brody, Gompertz, Logistic, Richards and von Bertalanffy. The criteria used to select the best model of the growth curve were the coefficient of determination, the asymptotic standard deviation, the mean absolute deviation of the waste and the asymptotic index. To study the allometric growth of the cuts were slaughtered 36 birds, two from each treatment, at onde day-old, 14, 28, 35, 42, 49 days, totaling 216 birds, were evaluate the weights of carcass (PCA), breast (PP), thighs (PC), drumsticks (PSC), legs (RSPP) and wings (PA). For the study of allometric growth of carcass composition, the carcasses of slaughtered animals were crushed, homogenised and analyzed in duplicate. Analyses were performed using dry matter (DM), crude protein (CP), ether extract (EE) and ash. The study of the relative growth of cuts and carcass composition of carcass was done through the model of the allometric equation of Huxley. Among the models studied of growth curve, the equations proposed by Gompertz, von Bertalanffy and Logistic reached convergence, and the Gompertz model best suited to describe the growth of the birds. In general, the males showed isogonic growth of cuts in the study when compared to the weight of the carcass. Females in turn, showed negative heterogonic growth (b <1) for most of the cuts studied. For the carcass composition, the allometric growth was isogonic (b = 1) for the deposition of protein and ash in most analyzes. The other nutrients showed, in general, early deposition compared to carcass weight.