Since the 1900s, the number of deaths attributable to cardiovascular disease has steadily risen. With the advent of antihypertensive drugs and non-invasive surgical procedures, such as intravascular stenting, these numbers have begun to level off. Despite this trend, the number of patients diagnosed with some form of cardiovascular disease has only increased. By 2030, prevalence of coronary heart disease is expected to increase approximately by 18% in the United States. By 2050, prevalence of peripheral arterial occlusive disease is expected to increase approximately by 98% in the U.S. No single drug or surgical intervention offers a complete solution to these problems. Thus, a multi-faceted regimen of lifestyle changes, medication, and device or surgical interventions is usually necessary. A potential adjunct therapy and cost-effective solution for treating cardiovascular disease that has been overlooked is neurostimulation. Recent studies show that using neurostimulation techniques, such as transcutaneous electrical nerve stimulation (TENS), can help to reduce ischemic pain, lower blood pressure, increase blood flow to the periphery, and decrease systemic vascular resistance. The mechanisms by which these hemodynamic changes occur is still under investigation. The primary aim of this thesis is to elucidate these mechanisms through a thorough synthesis of the existing literature on this subject. Neurostimulation, specifically TENS, is thought to modulate both the metaboreflex and norepinephrine release from sympathetic nerve terminals. To test the hypothesis that TENS increases local blood flow, decreases mean arterial pressure, and decreases cutaneous vascular resistance compared to placebo, in which the electrodes are attached but no electrical stimulation is applied, a protocol was developed to test the effect of neurostimulation on healthy subjects. Implementation of this protocol in a pilot study will determine if neurostimulation causes significant changes in blood flow using the most relevant perfusion measurement instrumentation. Before conducting this study, pre-pilot comparison studies of interferential current therapy (IFC) versus TENS, low frequency (4 Hz) TENS versus high frequency (100 Hz) TENS, and electrode placement on the back versus the forearm were conducted. The only statistically significant difference found was that the application of IFC on the back decreased the reperfusion time, meaning that the time required to reach the average baseline perfusion unit value after occlusion decreased. Further pre-pilot work investigating these different modalities and parameters is necessary to ensure that favorable hemodynamic changes can be detected in the pilot study.

No description available.

De nombreux efforts fournis sur l’avancement de la technologie de dépôt afin de répondre au besoin des utilisateurs des filtres interférentiels ont donné la naissance à la nouvelle génération des composants optiques. Les progrès techniques permettent de fabriquer les filtres avec la structure particulièrement complexe et atteindre les performances spectrales remarquables, mais aussi soulèvent de nouveaux problèmes au niveau de la diffusion. Les indicatrices de diffusion de ces filtres présentent les variations extrêmement rapides en fonction de l’angle de reprise et de la longueur d’onde, ce qui amoindrit sérieusement les performances des composants. Il est donc d’essentiel d’être capable de caractériser la diffusion lumineuse angulairement et spectralement résolue. L’objectif de cette thèse a alors été de développer l’outil expérimental, déduit pour la métrologie fine de la réponse spectrale et de la diffusion lumineuse. Le travail réalisé a donné naissance au banc SALSA (pour Spectral and Angular Light Scattering characterization Apparatus), un nouveau diffusomètre spectralement et angulairement résolu. Grâce au banc SALSA nous pouvons effectuer les mesures de diffusion sur large gamme spectrale [400 nm -1000 nm] avec la dynamique de 8 décades et la précision meilleure que 1%. Par ailleurs, le banc peut être utilisé pour la mesure de la transmission avec la dynamique de 12 décades, ce qui est performance unique sur l’échèle mondiale. / Due to market demand and technical progresses, a new generation of optical components requires much more sophisticated structures with a great number of layers. These complex structures enable to achieve severe optical performances but, at the same time, enhance light scattering processes. For these reasons, it is essential to develop a metrological tool which provides an accurate quantification of the spectral and angular behavior of scattering losses, with sufficient angular and spectral resolution. In order to face this issue, new investigations were performed during this PhD thesis and led to the development of the new scatterometer SALSA (Spectral and Angular Light Scattering characterization Apparatus). The use of both a broad-band source and a tunable filter allows to accurately select the illumination wavelength and the spectral bandwidth on the whole spectral range of CCD detectivity. Set-up SALSA allows us to perform the measurements of scattering losses on a wide spectral range (400-1000 nm), with high dynamics (>8 decades), high accuracy and low detectivity (a few 10-8 sr-1). Moreover, with set-up SALSA we are able to measure the transmission of interferential filters on the same spectral range, with high accuracy (1%) and a high dynamic (>10 decades, which is a unique performance).

M.Tech. / aim of this unblinded randomized control study was to compare Chiropractic Adjustive Therapy (CAT) to Interferential Current Therapy (IFC) as treatment for Painful Minor Intervertebral Dysfunction (PMID) in the lumbar spine. The effects of CAT and IFC on lumbar spine range of motion (ROM) and pain relief from PMID were also examined. The participants of the trials were treated at the Chiropractic Day Clinic at the University of Johannesburg. Thirty participants presenting with Low Back Pain (LBP) and PMID on segmental intervertebral examination were used for this study and divided into two groups of fifteen. Group A participants were treated with CAT applied to the painful intervertebral segment. Group B participants were treated with IFC over the painful intervertebral segment. The objective data for this research was recorded by the readings obtained from the application of transverse pressure by a Pressure Algometer to the lateral aspect of a painful spinous process. Further objective readings were taken using a Digital Inclinometer to measure the participants Range of Motion (ROM). Subjective data was obtained by an Oswestry Pain and Disability Index (ODI). The subjective and the objective data were both recorded at the first, fourth and seventh visit which took place over a three week period. The results of the study showed that Group A had a statistically significant decrease in Pressure Algometer Readings and ODI scores. Group A also showed a statistically significant improvement in ROM readings for Left Lateral Flexion, Left Rotation and Right Rotation. Group B did not show any statistical significance in either the subjective or objective data. Importantly, an Inter-group comparison for the Pressure Algometer Readings also revealed an increasing statistically significant difference between Group A and Group B from the first to the fourth and seventh visit. The pain elicited by transverse pressure to a spinous process is core to the diagnosis of PMID, which can result in many pain syndromes of vertebral origin (Maigne, 2006). This research provides evidence that CAT is more beneficial than IFC for the treatment of PMID in the lumbar spine over a short and longer period of time.

L'utilisation de filtre mosaïque hyperspectral semble être la solution idéale pour alléger les imageurs spectraux utilisés lors des missions spatiales. Les contraintes liées à ce type d'utilisation imposent l'emploi de filtres interférentiels multicouches. Ces travaux ont pour but de trouver des solutions pour réaliser un filtre mosaïque hyperspectral avec des filtres interférentiels et non avec les résines colorées traditionnellement utilisées. Pour ce faire une étude théorique sur la simplification des designs des empilements interférentiels a été effectuée. Il en ressort que les empilements restent épais, ce qui complique leur structuration. Plusieurs méthodes de structurations ont été étudiées. En particulier le lift-off qui est la technique actuellement utilisé aujourd'hui et le lift-up. Cette dernière présente l'avantage de ne pas mettre en série le risque technologique associé à chaque réalisation de filtre. Un trade-off entre ces deux techniques a été fait ainsi que des réalisations expérimentales. Celles-ci ont ensuite été caractérisées par un banc de mesure développé dans ce but qui a permis de valider expérimentalement la technique utilisée. / Hyperspectral mosaic filter appears to be the perfect solution to lighten the spectral imagers used in space missions. Such applications require the use of multilayer interference filters. This work aims to find solutions to achieve hyperspectral mosaic filter with interference filters rather than the conventionally used coloured resins. In order to achieve this, a theoretical study on the simplification of multilayer designs was performed. It appears that the stacks are thicker, which makes them difficult to pattern. Several methods of patterning were studied, especially the lift-off technique which is traditionally used and the lift-up. The latter has the advantage to avoid adding the technological risk associated with each filter production. A trade-off between these two techniques was done as well as experimental productions. These were then characterized by a bench developed for this purpose which has experimentally validate the technique used.

Neste trabalho é apresentada a simulação, fabricação e caracterização de filtros interferenciais empregando películas dielétricas amorfas depositadas pela técnica de deposição a vapor assistida por plasma (PECVD) sobre substratos de silício e de Corning Glass (7059). Os dispositivos ópticos foram construídos usando-se processos padrões de microeletrônica e consistiram em camadas periódicas com espessura e índice de refração apropriados para produzir picos da atenuação na transmitância da luz na região visível. Simulações numéricas precedentes foram realizadas baseando-se nas características ópticas das películas dielétricas. Para a caracterização dos filtros interferenciais, uma luz monocromática de um laser de He-Ne, foi injetada nos filtros e a luz obtida na saída foi conduzida então a um detector. O filtro depositado sobre Corning Glass (chamado de filtro vertical) e o filtro depositado sobre silício com cavidades (chamado de filtro suspenso) foram montados sobre dispositivos térmicos e angulares de modo a medir suas respostas à variação angular e térmica. Também, o filtro depositado sobre silício (chamado de filtro horizontal) foi montado sobre um dispositivo térmico, a fim de medir sua resposta à temperatura. Quando os filtros são submetidos a uma mudança na temperatura, uma variação do índice de refração devido ao efeito termo-óptico produz um deslocamento nos picos da atenuação, que podem ser previstos por simulações numéricas. Esta característica permite que estes dispositivos sejam usados como sensores termo-ópticos. Por outro lado, quando o filtro vertical e o filtro suspenso são submetidos a variações angulares entre a normal ao plano do filtro e o feixe de laser, uma variação na potência da luz de saída é produzida. Esta característica permite que estes dispositivos sejam usados como sensores angulares. / In this work, we present the simulation, fabrication and characterization of filters employing amorphous dielectric films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique on crystalline silicon and Corning Glass (7059) substrates. The optical devices were fabricated using standard microelectronic processes and consisted of periodic layers with appropriated thickness and refractive indexes to produce transmittance attenuation peaks in the visible region. For this, previous numerical simulations were realized based in the optical parameters of the dielectric films. For the characterization of the optical interferential filters, a monochromatic light, a He-Ne laser, was projected onto the filters and the transmitted output light was then conducted to a detector. The optical filters were produced on Corning Glass (here called vertical filter) and on silicon substrates. The silicon substrate was etch in KOH solution to form cavities and suspend part of the filter (here called suspended filter). The vertical and suspended filters were mounted on thermo and angular devices that allowed the measurement of the optical power as a function of temperature and angle changes. A second type of filter deposited over a silicon substrate (here called horizontal filter) was mounted on thermoelectric device, in order to control the temperature responses. When the filters are submitted to a change in temperature, a variation of the refractive index is originated in the dielectric film due to the thermo-optic effect (TOE), producing a shift in the attenuation peaks, which can be well predicted by numerical simulations. This characteristic allows these devices to be used as thermo-optic sensors. On the other hand, when the vertical filter and the suspended filter were subjected to an angular shift between the filter\'s normal and the laser, a variation of the output optical power is originated. This characteristic allows these devices to be used as angular sensors.

Contribution à l’étude de la réflectance et du confinement des modes dans les systèmes optiques stratifiés Résumé : Ce travail prolonge les études du changement de réflectivité des systèmes optiques stratifiés sous des contraintes mécanique et électrique. D’abord, nous quantifions le déplacement de la bande interdite photonique suite à une modification de l’angle d’incidence. Il en dérive une technologie bio-inspirée. Ensuite, c’est un champ électrique externe qui contrôle les propriétés de réflexion et de polarisation d’une multicouche construite à partir de cristaux liquides. Enfin, nous distinguons deux manières de confiner l’énergie électromagnétique. Ce travail s’attache à comprendre la nature des modes qui se propagent à la surface des milieux stratifiés. Par ailleurs, il montre que l’association de matériau gauche et de matériau droit pour former un guide d’onde permet de réduire la vitesse de la lumière de plusieurs ordres de grandeur. Contribution to the study of the reflectance and the mode confinement in optical stratified systems Abstract : This work extends the studies of change in reflectance in optical stratified systems under mechanical and electrical constraints. In the first part, we quantify the shift of the photonic bandgap following, a modification in the angle of incidence. We define the tools for the design of bio-inspired Bragg mirrors. In the second part, we adjust the reflection properties of a multilayer stack made of liquid crystals with an external electric field. Furthermore, we examine two distinct ways of producing light confinement. First, we contribute to the understanding of the nature of electromagnetic modes propagating at the surface of stratified media. Second, we show that a waveguide made of left- and right-handed materials can reduce the speed of light by several orders of magnitudes.

O objetivo do presente trabalho foi avaliar os efeitos da corrente interferencial na sensibilidade dolorosa e no torque muscular dos músculos flexores e extensores do joelho após a realização de um protocolo de exercícios excêntricos. A amostra foi constituída de 41 indivíduos saudáveis do sexo masculino com idade entre 18 e 33 anos, que foram divididos aleatoriamente em dois grupos experimentais: grupo corrente interferencial (n=21) e grupo placebo (n=20). Para indução da microlesão muscular, ambos os grupos realizaram 100 contrações musculares isocinéticas excêntricas máximas (10 séries de 10 repetições) dos músculos flexores e extensores do joelho na velocidade angular de 60°.s-1. No dia seguinte, os voluntários receberam tratamento com corrente interferencial ou tratamento placebo em ambos os grupos musculares. O tratamento foi realizado durante 30 minutos utilizando-se 4 kHz de frequência portadora (modulação de 80-150 Hz) e 125 μs de duração do pulso. O limiar de dor mecânica, o pico de torque e a concentração da proteína creatina cinase foram avaliados em quatro momentos diferentes: antes da indução da microlesão, imediatamente após o exercício, 24 horas após a indução e após o tratamento com corrente interferencial ou tratamento placebo. Tanto para os músculos flexores quanto extensores do joelho, ambos os grupos experimentais apresentaram uma redução significativa no pico de torque e no limiar de dor mecânica após a realização dos exercícios excêntricos, assim como uma elevação na concentração de proteínas marcadoras de lesão, mostrando que o protocolo de exercícios foi efetivo na indução da microlesão. Após o tratamento, apenas o grupo experimental, que recebeu a corrente interferencial, apresentou um aumento significativo no limiar de dor mecânica para ambos os grupos musculares avaliados, mostrando que a corrente foi efetiva na diminuição da sensibilidade dolorosa. Os valores de torque e a concentração das proteínas não sofreram alteração após o tratamento. Os resultados indicam que a corrente interferencial foi efetiva no tratamento da dor relacionada com microlesão muscular induzida por exercício excêntrico a partir de um aumento do limiar de dor mecânica nos músculos flexores e extensores do joelho. / The goal of the work presented here was to evaluate the effects of the interferential current in the pain sensibility and muscular torque of the flexor and extensor knee muscles after the performance of an eccentric exercise protocol. The sample was comprised of 41 healthy male individuals aged 18 to 33 years old, randomly divided into two experimental groups: interferential current group (n=21) and placebo group (n=20). To induce muscle soreness, both groups performed a hundred maximal isokinetic eccentric muscular contractions (10 series of 10 repetitions) in the flexor and extensor knee muscles, with an angular velocity of 60°.s- 1. On the following day volunteers were treated with interferential current or with the placebo treatment in both muscular groups. Treatment was carried out for 30 minutes using a 4 kHz carrier frequency (80-150 Hz) and a pulse duration of 125 μs. Mechanical pain threshold, peak torque and creatine kinase protein concentration were evaluated at four different times: before muscle soreness induction, immediately after exercise, 24 hours after induction and after the interferential current treatment or the placebo treatment. For both flexor and extensor knee muscles, both experimental groups presented a significant reduction in peak torque and mechanical pain threshold after performing the eccentric exercises, as well as a rise in injurysignaling protein concentration, demonstrating the efficiency of the exercise protocol in inducing muscle soreness. After treatment, only the experimental group that received the interferential current presented significant increases in mechanical pain threshold for both evaluated muscular groups, thus showing that the current was effective in diminishing pain sensitivity. Torque values and protein concentration underwent no changes after the treatment. The results pointed out that the interferential current was effective in the treatment of pain related to muscle soreness induced by eccentric exercise through an increase in mechanical pain threshold in the flexor and extensor knee muscles.

O objetivo do presente trabalho foi avaliar os efeitos da corrente interferencial na sensibilidade dolorosa e no torque muscular dos músculos flexores e extensores do joelho após a realização de um protocolo de exercícios excêntricos. A amostra foi constituída de 41 indivíduos saudáveis do sexo masculino com idade entre 18 e 33 anos, que foram divididos aleatoriamente em dois grupos experimentais: grupo corrente interferencial (n=21) e grupo placebo (n=20). Para indução da microlesão muscular, ambos os grupos realizaram 100 contrações musculares isocinéticas excêntricas máximas (10 séries de 10 repetições) dos músculos flexores e extensores do joelho na velocidade angular de 60°.s-1. No dia seguinte, os voluntários receberam tratamento com corrente interferencial ou tratamento placebo em ambos os grupos musculares. O tratamento foi realizado durante 30 minutos utilizando-se 4 kHz de frequência portadora (modulação de 80-150 Hz) e 125 μs de duração do pulso. O limiar de dor mecânica, o pico de torque e a concentração da proteína creatina cinase foram avaliados em quatro momentos diferentes: antes da indução da microlesão, imediatamente após o exercício, 24 horas após a indução e após o tratamento com corrente interferencial ou tratamento placebo. Tanto para os músculos flexores quanto extensores do joelho, ambos os grupos experimentais apresentaram uma redução significativa no pico de torque e no limiar de dor mecânica após a realização dos exercícios excêntricos, assim como uma elevação na concentração de proteínas marcadoras de lesão, mostrando que o protocolo de exercícios foi efetivo na indução da microlesão. Após o tratamento, apenas o grupo experimental, que recebeu a corrente interferencial, apresentou um aumento significativo no limiar de dor mecânica para ambos os grupos musculares avaliados, mostrando que a corrente foi efetiva na diminuição da sensibilidade dolorosa. Os valores de torque e a concentração das proteínas não sofreram alteração após o tratamento. Os resultados indicam que a corrente interferencial foi efetiva no tratamento da dor relacionada com microlesão muscular induzida por exercício excêntrico a partir de um aumento do limiar de dor mecânica nos músculos flexores e extensores do joelho. / The goal of the work presented here was to evaluate the effects of the interferential current in the pain sensibility and muscular torque of the flexor and extensor knee muscles after the performance of an eccentric exercise protocol. The sample was comprised of 41 healthy male individuals aged 18 to 33 years old, randomly divided into two experimental groups: interferential current group (n=21) and placebo group (n=20). To induce muscle soreness, both groups performed a hundred maximal isokinetic eccentric muscular contractions (10 series of 10 repetitions) in the flexor and extensor knee muscles, with an angular velocity of 60°.s- 1. On the following day volunteers were treated with interferential current or with the placebo treatment in both muscular groups. Treatment was carried out for 30 minutes using a 4 kHz carrier frequency (80-150 Hz) and a pulse duration of 125 μs. Mechanical pain threshold, peak torque and creatine kinase protein concentration were evaluated at four different times: before muscle soreness induction, immediately after exercise, 24 hours after induction and after the interferential current treatment or the placebo treatment. For both flexor and extensor knee muscles, both experimental groups presented a significant reduction in peak torque and mechanical pain threshold after performing the eccentric exercises, as well as a rise in injurysignaling protein concentration, demonstrating the efficiency of the exercise protocol in inducing muscle soreness. After treatment, only the experimental group that received the interferential current presented significant increases in mechanical pain threshold for both evaluated muscular groups, thus showing that the current was effective in diminishing pain sensitivity. Torque values and protein concentration underwent no changes after the treatment. The results pointed out that the interferential current was effective in the treatment of pain related to muscle soreness induced by eccentric exercise through an increase in mechanical pain threshold in the flexor and extensor knee muscles.

O objetivo do presente trabalho foi avaliar os efeitos da corrente interferencial na sensibilidade dolorosa e no torque muscular dos músculos flexores e extensores do joelho após a realização de um protocolo de exercícios excêntricos. A amostra foi constituída de 41 indivíduos saudáveis do sexo masculino com idade entre 18 e 33 anos, que foram divididos aleatoriamente em dois grupos experimentais: grupo corrente interferencial (n=21) e grupo placebo (n=20). Para indução da microlesão muscular, ambos os grupos realizaram 100 contrações musculares isocinéticas excêntricas máximas (10 séries de 10 repetições) dos músculos flexores e extensores do joelho na velocidade angular de 60°.s-1. No dia seguinte, os voluntários receberam tratamento com corrente interferencial ou tratamento placebo em ambos os grupos musculares. O tratamento foi realizado durante 30 minutos utilizando-se 4 kHz de frequência portadora (modulação de 80-150 Hz) e 125 μs de duração do pulso. O limiar de dor mecânica, o pico de torque e a concentração da proteína creatina cinase foram avaliados em quatro momentos diferentes: antes da indução da microlesão, imediatamente após o exercício, 24 horas após a indução e após o tratamento com corrente interferencial ou tratamento placebo. Tanto para os músculos flexores quanto extensores do joelho, ambos os grupos experimentais apresentaram uma redução significativa no pico de torque e no limiar de dor mecânica após a realização dos exercícios excêntricos, assim como uma elevação na concentração de proteínas marcadoras de lesão, mostrando que o protocolo de exercícios foi efetivo na indução da microlesão. Após o tratamento, apenas o grupo experimental, que recebeu a corrente interferencial, apresentou um aumento significativo no limiar de dor mecânica para ambos os grupos musculares avaliados, mostrando que a corrente foi efetiva na diminuição da sensibilidade dolorosa. Os valores de torque e a concentração das proteínas não sofreram alteração após o tratamento. Os resultados indicam que a corrente interferencial foi efetiva no tratamento da dor relacionada com microlesão muscular induzida por exercício excêntrico a partir de um aumento do limiar de dor mecânica nos músculos flexores e extensores do joelho. / The goal of the work presented here was to evaluate the effects of the interferential current in the pain sensibility and muscular torque of the flexor and extensor knee muscles after the performance of an eccentric exercise protocol. The sample was comprised of 41 healthy male individuals aged 18 to 33 years old, randomly divided into two experimental groups: interferential current group (n=21) and placebo group (n=20). To induce muscle soreness, both groups performed a hundred maximal isokinetic eccentric muscular contractions (10 series of 10 repetitions) in the flexor and extensor knee muscles, with an angular velocity of 60°.s- 1. On the following day volunteers were treated with interferential current or with the placebo treatment in both muscular groups. Treatment was carried out for 30 minutes using a 4 kHz carrier frequency (80-150 Hz) and a pulse duration of 125 μs. Mechanical pain threshold, peak torque and creatine kinase protein concentration were evaluated at four different times: before muscle soreness induction, immediately after exercise, 24 hours after induction and after the interferential current treatment or the placebo treatment. For both flexor and extensor knee muscles, both experimental groups presented a significant reduction in peak torque and mechanical pain threshold after performing the eccentric exercises, as well as a rise in injurysignaling protein concentration, demonstrating the efficiency of the exercise protocol in inducing muscle soreness. After treatment, only the experimental group that received the interferential current presented significant increases in mechanical pain threshold for both evaluated muscular groups, thus showing that the current was effective in diminishing pain sensitivity. Torque values and protein concentration underwent no changes after the treatment. The results pointed out that the interferential current was effective in the treatment of pain related to muscle soreness induced by eccentric exercise through an increase in mechanical pain threshold in the flexor and extensor knee muscles.