Suchomel, TJ, Bailey, CA, Sole, CJ, Grazer, JL, and Beckham, GK. Using reactive strength index-modified as an explosive performance measurement tool in Division I athletes. J Strength Cond Res 29(4): 899-904, 2015 - The purposes of this study included examining the reliability of reactive strength index-modified (RSImod), the relationships between RSImod and force-time variables, and the differences in RSImod between male and female collegiate athletes. One hundred six Division I collegiate athletes performed unloaded and loaded countermovement jumps (CMJs). Intraclass correlation coefficients and typical error expressed as a coefficient of variation were used to establish the relative and absolute reliability of RSImod, respectively. Pearson zero-order product-moment correlation coefficients were used to examine the relationships between RSImod and rate of force development, peak force (PF), and peak power (PP) during unloaded and loaded jumping conditions. Finally, independent samples t-tests were used to examine the sex differences in RSImod between male and female athletes. Intraclass correlation coefficient values for RSImod ranged from 0.96 to 0.98, and typical error values ranged from 7.5 to 9.3% during all jumping conditions. Statistically significant correlations existed between RSImod and all force-time variables examined for male and female athletes during both jumping conditions (p ≤ 0.05). Statistically significant differences in RSImod existed between male and female athletes during both unloaded and loaded CMJs (p < 0.001). Reactive strength index-modified seems to be a reliable performance measurement in male and female athletes. Reactive strength index-modified may be described and used as a measure of explosiveness. Stronger relationships between RSImod, PF, and PP existed in female athletes as compared with that in male athletes; however, further evidence investigating these relationships is needed before conclusive statements can be made. Male athletes produced greater RSImod values as compared with that produced by female athletes.

The purpose of this study was to examine the differences in reactive strength index-modified (RSImod), jump height (JH), and time to takeoff (TTT) between 6 U.S. collegiate sport teams. One hundred six male and female Division I collegiate athletes performed unloaded (<1 kg) and loaded (20 kg) countermovement jumps as part of an ongoing athlete monitoring program. Reactive strength index-modified, JH, and TTT values for each team were compared using 1-way analysis of variance. Statistically significant differences in RSImod (p < 0.001), JH (p < 0.001), and TTT (p 0.003) existed between teams during the unloaded jumping condition. Similarly, statistically significant differences in RSImod (p < 0.001), JH (p < 0.001), and TTT (p 0.028) existed between teams during the loaded jumping condition. Men's soccer and baseball produced the greatest RSImod values during both the unloaded and loaded jumping conditions followed by women's volleyball, men's tennis, women's soccer, and women's tennis. The greatest JH during unloaded and loaded jumping conditions was produced by men's baseball followed by men's soccer, women's volleyball, men's tennis, women's soccer, and women's tennis. Men's soccer produced shorter TTT compared with men's baseball (12.7%) and women's soccer (13.3%) during the unloaded and loaded jumping conditions, respectively. Collegiate sport teams exhibit varying reactive strength characteristics during unloaded and loaded jumping conditions. Understanding the differences in RSImod between sports may help direct the creation of training and monitoring programs more effectively for various sports.

Considering the communication systems with cyclic prefix (CP), such as orthogonal frequency-division multiplexing (OFDM) modulation and single-carrier cyclic prefixed (SCCP) modulation, when the length of CP is longer than the channel length, the use of cyclic prefix (CP) does not only eliminate the inter-block interference, but also convert linear convolution of the transmitted signal with the channel into circular convolution. Unfortunately, the use of CP significantly decreases the bandwidth utilization. Therefore, to reduce the length of CP is a critical issue. The thesis investigates that how to design a channel-shortening equalizer (CSE) at receiver which forces the length of the effective channel response as short as the CP length. The thesis describes the signal model as a matrix form. The effect channel response after CSE is investigated and then the coefficient of channel shortening filter is obtained using singular value decomposition method under various criterions. We further propose a novel CSE maximizing the shortening signal-to-interference ratio. In addition, it is demonstrated that the proposed CSE has the same performance as the conventional scheme but a lower computation complexity.

Abstract Due to the implementation of shortening working-hour, a lot of enterprises chose to respond to the coming of the ¡§84 working-hour policy¡¨ by reducing salary and freezing personnel matters. Since the medical treatment industry different from other industries considering the fact that the medical treatment industry is a non-profitable institute and also a manpower and cost-intensive industry. This research aims to learn, as far as the shortening working-hour is concerned, whether or not exercising manpower for the medical treatment industry is more difficult than that in other industries. The cognition and viewpoints of the medical treatment industry towards shortening working-hour, and what types of working-hour strategies, educational training strategies, operation cost strategies, and management strategies, should be applied in terms of hospital management. This research aims to study the understanding of the medical treatment industry concerning the shortening of working-hour and their corresponding strategies. 540 copies of questionnaire were dispensed and 133 copies were collected and analyzed through SPSS. The followings are the findings of this research: 1. The understanding of hospitals on shortening working-hour: On the one hand, 56.4% agreed with the implementation of shortening working-hour policy because it helps to moderate the unemployment. On the other hand, over 50% disagreed with the above statement on half of the other entries. The results suggested that hospitals were generally not satisfied by the implementation of the said policy. 2. Hospitals¡¦ strategies corresponding to the shortening working-hour policy: ¡]1¡^57.1% (the highest percentage) choose not to complement when having job vacancy as their working-hour strategy. ¡]2¡^69.9% applied educational training in improving their employees¡¦ to understand on time and cost-reducing as their educational strategy; 64.7% focused to train their employees to have multiple specialties; 54.1% choose to enhance the training on information and computer application, and operating skills. ¡]3¡^75.6% choose to reduce the manpower and expenses under the existing scope as the operation cost strategy; 56.5% choose to enhance the internal information passing and increase the efficiency. ¡]4¡^83.5% choose to improve the manpower exercising as the management strategy; 66.9% choose to simplify the working procedures; 55.6% choose to improve the communications between employer and employees and the collaboration; 54.9% focused on the implementation of the merit system to improve the working efficiency 3. The current situation of hospitals after the implementation of shortening working-hour policy: Over half of the hospitals conform to the Labor Law on daily normal working hour and weekly normal working hour. However, few changes have been made on the ways of employment. For example, although 66.9% hired part-time works, most of them were under 10 part-time workers. Furthermore, as far as contract taking and outsourcing are concerned, the percentage has not exceeded 50%. Nonetheless, as far as educational training is concerned, 51.9% choose to have partial public-holiday and partial private-holiday which suggested that hospitals expected their employees to adopt the partial private-holiday way to improve their professional ability when they have more leisure time after the working hour has been shortened Keywords: shortening working-hour, flexible working hour, working-hour strategy, educational training strategy, operation cost strategy, management strategy

This thesis investigates applications of puncturing in error-correction coding and physical layer security with an emphasis on binary and non-binary LDPC codes. Theoretical framework for the analysis of punctured binary LDPC codes at short block lengths is developed and a novel decoding scheme is designed that achieves considerably faster convergence than conventional approaches. Subsequently, optimized puncturing and shortening is studied for non-binary LDPC codes over binary input channels. Framework for the analysis of punctured/shortened non-binary LDPC codes over the BEC channel is developed, which enables the optimization of puncturing and shortening patterns. Insight from this analysis is used to develop algorithms for puncturing and shortening of non-binary LDPC codes at finite block lengths that perform well. It is confirmed that symbol-wise puncturing is generally bad and that bit-wise punctured non-binary LDPC codes can significantly outperform their binary counterparts, thus making them an attractive solution for future communication systems; both for error-correction and distributed compression. Puncturing is also considered in the context of physical layer security. It is shown that puncturing can be used effectively for coding over the wiretap channel to hide the message bits from eavesdroppers. Further, it is shown how puncturing patterns can be optimized for enhanced secrecy. Asymptotic analysis confirms that eavesdroppers are forced to operate at BERs very close to 0.5, even if their signal is only slightly worse than that of the legitimate receivers. The proposed coding scheme is naturally applicable at finite block lengths and allows for efficient, almost-linear time encoding. Finally, it is shown how error-correcting codes can be used to solve an open problem of compressing data encrypted with block ciphers such as AES. Coding schemes for multiple chaining modes are proposed and it is verified that considerable compression gains are attainable for binary sources.

This dissertation examines multiple exponence (ME) phenomena in the non-inflectional morphology of three languages: Nuu-chah-nulth (Wakashan), Central Yup'ik (Eskimo), and Korean (language isolate or Altaic). These languages exhibit a common property: ME comprised of a non-inflectional suffix and one or more base modifications. The base modifications involve a vowel length change and reduplication in Nuu-chah-nulth, various types of deletion in Central Yup’ik, and vowel shortening in Korean. This dissertation pursues four research questions: (1) what criteria diagnose morphophonological alternations as ME and do the criteria apply to all cases of ME to the same degree? (2) Does derivational ME differ from inflectional ME? (3) Does one exponent play a more significant role in expressing semantic/syntactic information than another? (4) How is derivational ME formally accounted for? In pursuit of these research questions, this study proposes, based on Matthews’s (1972) study, four criteria to distinguish ME from other phonological alternations. Only the two criteria, Non-phonological condition and Consistent co-occurrence are obligatory; two others, Phonological Consistency and No exceptions on base selection, may be violated, suggesting that ME parameters occur along a continuum. This dissertation also proposes derivational classes according to patterns of base modification. Derivational classes play an important role in formulating Word Formation Rules (WFRs), in that they provide the morphological conditions for the structural description of base modification rules. Significantly, semantic/syntactic information is encoded in suffixation, capturing the fact that the large number of meanings that suffixes carry (approximately 500) cannot be mapped onto a limited number of base modifications (ranging from two to fourteen). The evidence that suffixes convey meaning supports the claim that ME requires two different types of WFR, a suffixation rule that conveys semantic/syntactic information, and base modification rules that do not. Also, this study suggests that suffixes are the main exponent of ME because they make the main contribution to the meanings conveyed through ME. This study contributes to a theory of morphology not only in that seemingly distinct processes receive a unified analysis as ME, but also in that the distinct processes are formally accounted for, expanding the WP approach to derivational morphology. / Graduate / 0290 / sung17hwa@gmail.com

Les orogènes à double vergence sont classiquement définis comme deux prismes critiques opposés (pro et retro) qui évoluent ensemble. Les études récentes montrent que les rétro-prismes et leurs bassins d’avant-pays associés se comportent différemment des pro-prismes. Cependant, ni les facteurs qui mènent un orogène à devenir doublement vergent, ni la relation entre le pro- et rétro-prisme ne sont bien compris. Le but de cette étude est d'améliorer notre connaissance 1) de la relation entre le pro- et le rétro-prisme pendant l'orogénèse, 2) des facteurs contrôlant l'évolution d'un orogène à double vergence, et 3) d’un lien dynamique possible entre le pro- et le rétro-prisme. Répondre à ces questions nécessite une connaissance améliorée de l'évolution d'un orogène à double vergence. Nous nous sommes concentrés sur les Pyrénées Orientales, en raison de la grande quantité de données disponibles. Nous avons effectué une étude de terrain tectono-stratigraphique détaillée à l’est du Massif de Saint Barthelemy et dans l’avant-pays autour de Lavelanet (plaque Européenne). Notre interprétation d’une coupe restaurée intègre une configuration crustale pré-orogenique en tant qu'une marge hyper-amincie. Nous relions l'évolution détaillée du rétro-prisme à celle du pro-prisme (plaque Ibérique), afin de mieux contraindre la dynamique à l'échelle crustale. Nous subdivisons l'évolution des Pyrénées Orientales en quatre phases. La première phase (Crétacé Supérieur) est caractérisée par la fermeture d'un domaine de manteau exhumé entre les plaques et l'inversion synchrone d'un système de rift riche en sel et thermiquement déséquilibré. Le raccourcissement était distribué de façon égale entre les deux marges pendant cette première phase d’inversion. Une phase de quiescence (Paléocène), limitée au rétro-prisme, enregistre la transition entre l'inversion et la phase de collision. La phase de collision principale (Éocène) enregistre le taux de raccourcissement le plus élevé, et était principalement accommodé dans le pro-prisme. Pendant la phase finale (Oligocène) le rétro-prisme était largement inactif et le raccourcissement du pro-prisme a ralenti. Cela démontre que la relation entre le pro- et rétro-prisme change avec le temps. Nous avons utilisé des modèles numériques 2D thermomécaniques à l'échelle lithosphérique pour simuler l'évolution d'un orogène à double vergence s'initie après avec un rift. Nos résultats montrent un modèle évolutif similaire à celui observé dans les Pyrénées Orientales avec une phase d'inversion du rift approximativement symétrique suivie d'une phase de collision asymétrique. L'héritage du rift est essentiel pour permettre le développement d’un orogène à double vergence. Des autres facteurs, comme les processus de surface et la déformation de la couverture, ont un effet significatif sur la structure crustale et la répartition du raccourcissement entre les deux prismes. Un niveau de décollement (sel) à la base de la couverture favorise la formation d'un empilement antiformal d’écailles crustales, similaire à la géométrie observée dans la Zone Axiale des Pyrénées, en formant un prisme à faible pente qui force la déformation crustale à se concentrer dans l'arrière-pays. Enfin, nous montrons que l'évolution des pro- et rétro-prismes est inextricablement liée : des événements ou des conditions d'un côté de l'orogène ont un effet direct sur l'autre côté de l'orogène. Ceci est clairement démontré dans nos modèles par des variations constantes des taux de raccourcissement du pro- et rétro-prisme en réponse à l'accrétion dans le pro-prisme. Le Haut Atlas (Maroc) et Pyrénées peuvent être respectivement considérés comme des exemples d'inversion de rift symétrique et de phases de collision asymétrique ultérieures / The doubly vergent nature of some natural orogens is classically understood as two opposing thrust wedges (pro and retro) that comply with critical taper theory. The evidence that retro-wedges and their associated basins behave differently from their pro-wedge counterparts has been steadily increasing over the past few decades. However, what causes an orogen to become doubly vergent is currently not well understood. Nor is the relationship between the pro- and retro-wedge during the evolution of a doubly vergent orogen. It is the aim of this work to improve our understanding of: 1) how the pro- and retro-wedges relate to each other during the orogenic process, 2) what factors control the evolution of a doubly vergent orogen and 3) a possible link between the pro- and retro-wedge. Answering these questions requires an improved knowledge of the evolution of a doubly vergent orogen. We focussed on the Eastern Pyrenees as a type example of a doubly vergent orogen, due to the large amount of available data. We performed a detailed tectonostratigraphic study of the retro-foreland of the Eastern Pyrenees (European plate), updating the interpretation based on recent insights into its hyperextended rift origins. We link the evolution of the retro-foreland to that of the pro-foreland (Iberian plate) in order to derive insight into the crustal scale dynamics. Based on cross section restoration, reconstructed shortening rates and subsidence analysis, we subdivide the East Pyrenean evolution into four phases. The first (Late Cretaceous) phase is characterised by closure of an exhumed mantle domain between the European and Iberian rifted margins, and simultaneous inversion of a salt-rich, thermally unequilibrated rift system. Shortening was distributed roughly equally between both margins during this early inversion phase. Following inversion, a quiescent phase (Paleocene) was apparently restricted to the retro-foreland. This phase may record the period of transition between inversion and full collision in the Eastern Pyrenees. The main collision phase (Eocene) records the highest shortening rates, which was predominantly accommodated in the pro-wedge. Retro-wedge shortening rates were lower than during the rift inversion phase. During the final phase (Oligocene) the retro-wedge was apparently inactive and shortening of the pro-wedge slowed. This demonstrates that the relationship between the pro- and retro-wedges changes through time. We used lithosphere-scale thermo-mechanical numerical models to simulate the evolution of a doubly vergent orogen. Our results show a similar evolutionary pattern as observed in the Pyrenees: A roughly symmetrical rift inversion phase is followed by an asymmetric collision phase. Rift inheritance was found to be essential for enabling double vergence. Other factors, such as surface processes and thin-skinned deformation, were found to have a significant effect on the crustal structure and strain partitioning between both wedges. A salt décollement layer in the sedimentary cover promotes the formation of a crustal antiformal stack such as observed in the Pyrenees and Alps by forming a wide and low-taper thin-skinned fold-and-thrust belt that forces crustal deformation to focus in the hinterland. Finally, we show that the evolution of the pro- and retro-wedges is inextricably linked: events or conditions on one side of the doubly vergent orogen have an immediate effect on the other side of the orogen. This is clearly demonstrated in our models by constant variations in shortening rates of the pro- and retro-wedge in response to accretion of new pro-wedge thrust sheets. The High Atlas (Morocco) and Pyrenees can be seen as examples of symmetric rift inversion and later asymmetric collision phases, respectively

Orientador: Gil Lucio Almeida / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-06T21:23:30Z (GMT). No. of bitstreams: 1 Santos_MarcusViniciusRezendedos_M.pdf: 2514721 bytes, checksum: a7b1ab66caadf0d4fb9a3367038033d5 (MD5) Previous issue date: 2005 / Resumo: Neste trabalho, foram investigados efeitos de condições especiais como o envelhecimento e a Doença de Parkinson no controle de movimentos reversos do cotovelo, realizados com um atraso variável entre a ida (Ml) e a volta (M2) do mesmo. Outro objetivo foi verificar se o ciclo de alongamento-encurtamento (CAE) age como potencializador da contração muscular nessa população. Foram recrutados 12 voluntários, sendo seis sujeitos saudáveis (três homens e três mulheres) com idades entre 51 e 71 anos (Média = 62.33 e DP = 8.95) e seis portadores da doença de Parkinson (três homens e três mulheres) com idades entre 59 e 77 anos (Média = 68.66 e DP = 7.47). Eles realizaram movimentos uni-articulares rápidos de reversão com o cotovelo, que se movia em direção à um alvo (Ml) e depois retomava à posição inicial (M2). Esses movimentos foram realizados em três diferentes distâncias (20°, 40° e 60°) e entre os dois componentes (Ml e M2) foi realizado um atraso variável (Os, 0.2s, 0.5s e ls). O deslocamento angular do cotovelo foi registrado por um sistema óptico de análise do movimento (OPTOTRAK@ 3020) e a atividade elétrica dos músculos braquiorradial (BRR) e cabeça lateral do tríceps braquial (TR) foi registrada através de um eletromiógrafo EMG DelSYS (modelo DE2.2L) com eletrodos de superficie. O envelhecimento saudável não influenciou os padrões EMG utilizados por esses indivíduos para ativar os músculos agonista e antagonista na realização de movimentos uni-articulares com reversão com diferentes atrasos. A velocidade dos movimentos executados por esses indivíduos foi mais baixa devido ao uso de um padrão semelhante aos sujeitos jovens, porém com uma menor quantidade de ativação. Os parkinsonianos moveram mais lentamente que os idosos saudáveis e indivíduos saudáveis devido a algumas alterações na modulação da atividade EMG. Apesar de apresentarem a manutenção do padrão trifásico, a atividade elétrica dos músculos ocorreu na forma de vários bursts altemantes durante toda a realização da tarefa, o que provocou uma redução na quantidade de ativida elétrica dos músculos. Os parkinsonianos não reduziram a magnitude do segundo burst agoninos movimentos sem atraso, o que trouxe uma dificuldade maior para reverter os moviment< Por fim, notou-se que os indivíduos portadores da doença de Parkinson relaxavam menos a SI musculatura e iniciavam o retomo à posição inicial necessitando de uma atividade maior do 1 para gerar uma velocidade igual à dos indivíduos saudáveis, o que não aconteceu. ( movimentos que reverteram sem atraso apresentaram um valor maior da velocidade movimento de retomo à posição inicial, mesmo nos portadores da doença de Parkinso confirmando a ação potencializadora do ciclo de alongamento-encurtamento (CAE) sobre músculo tríceps. Isso suporta a influência, tanto dos reflexos (gerados pelo estiramento muscula quanto da energia potencial armazenada pelo músculo e tendão, que têm suas origens na fa: excêntrica do CAE e são liberados no movimento de volta (fase concêntrica). Palavras-chave: Movimentos reversos, doença de Parkinson, ciclo de alongamento encurtamento, eletromiografia e cinemática / Abstract: Within this study were investigated the effects of special conditions like aging and the Parkinson's disease on the control ofreversal movements ofthe elbow joint performed with a variable delay between the two components (Ml and M2) ofreversal. Another aim was to verify if the stretch-shortening cycle exerts his potentiating effects on muscular contraction in this population. To perform these observations, 12 volunteers were recruited. Six of them (3 males and 3 females) were normal at their neurological assessment and were between 51 and 71 years of age (Mean = 62.33 e S.D.= 8.95), and the other six (3 males and 3 females) had been diagnosised with Parkinson disease and were between 59 and 77 years old (Mean = 68.66 e S.D. = 7.47). They executed fast single-joint movements with a reversal, moving towards a target (Ml) and getting back to the initial position (M2). These movements were accomplished in three different distances (20°, 40° and 60°) and between the two components ofreversal (Ml e M2) there were variable delays (Os, 0.2s, 0.5s eIs). The elbow angle was recorded using a optoelectric system of motion analysis (OPTOTRAK@ 3020) and the electrical activity of braquioradialis (BRR) and lateral head of triceps brachi (TR) muscles were recorded by a electromyograph EMG DelSYS (model DE2.2L) with surface electrodes placed over the muscles bellies. The aging did not affect the EMG patterns used by these persons in activating the agonist and antagonist muscles to accomplish single-joint movements with a delay between the movements toward the target and the return to the initial position. The velocity of movements executed by the elder1y volunteers was lower due to the fact that the same strategy applied to young hea1thy persons was used, however with less EMG activity. The volunteers with Parkinson's disease moved slower than the heaIthy elderly and young subjects due to aIterations in the modulation of EMG activity. Altough they kept the triphasic pattern, the EMG showed multiple bursts that aItemated during the task accomplishmen~ which decreased the amount of ellectricaI activity. Besides, they did not reduce the magnitude of second agonist burst in the reversaI movements without delay, what made the reversion harder. FinaIly, it was noticed that the parkinsonians showed less relaxation of his muscles during the intervaI between TI-T4, and started the return movement needing more TR activity to produce the same velocity, when compared to heaIthy persons, which was not the case. Those movements that reverted with no delay showed higher values concerning the second peak ofvelocity, even within the volunteers with Parkinson disease, sustaining the potentianting action of SSC over the triceps muscle. This effect comes from the influence of reflexes (generated by the muscle stretching), as well as the storage of elastic energy in the muscle and tendon in the eccentric phase of SSC, which are released at the movement of returning (concentric phase) / Mestrado / Fisiologia / Mestre em Biologia Funcional e Molecular

The three geodesics theorem of Lusternik and Schnirelmann asserts that for every Riemannian metric on the 2-sphere, there exist at least three embedded closed geodesics. In the process of determining the geodesics as critical points of the energy or length functional, a suitable method of curve shortening is needed. It has been suggested to use the so-called curve shortening flow as it continuously deforms smooth embedded curves while naturally preserving their embeddedness. In the 1980s, the investigation of the curve shortening flow began and a proof of the Lusternik-Schnirelmann theorem using the flow was sketched. We build upon these results. After introducing the curve shortening flow, we prove the well-known result that the geodesic curvature of a smooth embedded closed curve on a smooth closed two-dimensional Riemannian manifold decreases smoothly to zero, provided the curve evolves forever under the flow. From this, we prove subconvergence to an embedded closed geodesic, using mainly local arguments. After introducing, in the form of Lusternik-Schnirelmann theory, the topological machinery employed in the process of determining critical points of certain functions, we turn to the three geodesics theorem which we prove under a few assumptions. For the round metric on the 2-sphere, we deformation retract a suitable space of unparametrized curves onto a simpler space of which we determine the homology groups relative to a subspace which deformation retracts onto the subspace of point curves. As this yields three subordinate homology classes, proving the validity of Lusternik-Schnirelmann theory for the curve shortening flow and the length functional on our space of curves completes the proof.

A finite element (FE) model for the generation of single fiber action potentials (SFAPs) in a muscle undergoing various degrees of fiber shortening has been developed. The muscle is assumed to be fusiform with muscle fibers following a curvilinear path described by a Gaussian function. Different degrees of fiber shortening are simulated by changing the parameters of the fiber path and maintaining the volume of the muscle constant. The conductivity tensor is adapted to the muscle fiber orientation. At each point of the volume conductor, the conductivity of the muscle tissue in the direction of the fiber is larger than that in the transversal direction. Thus, the conductivity tensor changes point-by-point with fiber shortening, adapting to the fiber paths. An analytical derivation of the conductivity tensor is provided. The volume conductor is then studied with an FE approach using the analytically derived conductivity tensor (Mesin, Joubert, Hanekom, Merletti&Farina 2006). Representative simulations of SFAPs with the muscle at different degrees of shortening are presented. It is shown that the geometrical changes in the muscle, which imply changes in the conductivity tensor, determine important variations in action potential shape, thus affecting its amplitude and frequency content. The model is expanded to include the simulation of motor unit action potentials (MUAPs). Expanding the model was done by assigning each single fiber (SF) in the motor unit (MU) a random starting position chosen from a normal distribution. For the model 300 SFs are included in an MU, with an innervation zone spread of 12 mm. Only spatial distribution was implemented. Conduction velocity (CV) was the same for all fibers of the MU. Representative simulations for the MUAPs with the muscle at different degrees of shortening are presented. The influence of interelectrode distance and angular displacement are also investigated as well as the influence of the inclusion of the conductivity tensor. It has been found that the interpretation of surface electromyography during movement or joint angle change is complicated owing to geometrical artefacts i.e. the shift of the electrodes relative to the muscle fibers and also because of the changes in the conductive properties of the tissue separating the electrode from the muscle fibers. Detection systems and electrode placement should be chosen with care. The model provides a new tool for interpreting surface electromyography (sEMG) signal features with changes in muscle geometry, as happens during dynamic contractions. / Dissertation (MEng (Bio-Engineering))--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / MEng (Bio-Engineering) / unrestricted