Le but de ce travail a été d’étudier l’effet de la stimulation ß-adrénergique (ßADR) (en utilisant l’isoprotérenol (ISO), l’agoniste ß-adrénergique) sur l’entrée de Ca dans le myoplasme du muscle squelettique à contraction rapide de grenouille suite à des stimulations électriques. Dans ce travail, en nous servant de la méthode d’EGTA/rouge de phénol (Pape et al., 1995) associée aux techniques de courant imposé et de voltage imposé, nous avons étudié l’effet de la stimulation ßADR en mesurant les paramètres intracellulaires pouvant affecter l’entrée de Ca dans le myoplasme tels le pH intracellulaire, le contenu total en Ca du réticulum sarcoplasmique, la vitesse de l’entrée de Ca dans le myoplasme, la quantité de Ca extracellulaire entré dans le myoplasme et le mouvement de charge intra membranaire suite à des stimulations électriques. Nous avons observé une augmentation de l’entrée de Ca dans le myoplasme sous l'effet d'ISO (chez les fibres exposées à 10 μM d’ISO pendant 8 minutes) et ce, en réponse à des potentiels d’actions obtenus à l'aide de la technique de courant imposé. Comme cet effet a été en relation directe avec le Ca extracellulaire, nous avons utilisé d'autres stratégies pour élucider davantage l'effet ß-adrénergique sur une possible augmentation importante de l’entrée de Ca extracellulaire dans le myoplasme. En premier lieu, les expériences en courant imposé avec les fibres vidangées de leur Ca sarcoplasmique ont permis de mesurer la quantité excédentaire de Ca extracellulaire entré dans le myoplasme suite à des stimulations électriques chez les fibres exposées à ISO (10 μM, 8 minutes). Toutefois, la quantité mesurée de Ca d'origine extracellulaire entré dans le myoplasme ne correspond pas à la totalité de l'augmentation de l'entrée de Ca dans le myoplasme en réponse à un train de potentiels d’action (PA) mesurée dans nos expériences en courant imposé. En deuxième lieu, les expériences avec la technique de voltage imposé n’ont pas démontré qu’ISO augmente de manière significative le pic d’amplitude de courant entrant de Ca tel que proposé par Arreola et al. (J. Physiol (Lond) 1987; 393:307-330). Cependant, ISO a diminué le temps au mi pic du courant entrant de Ca indiquant ainsi que l’activation du courant entrant calcique se fait plus rapidement sous l’effet d’ISO. En nous servant des protocoles de pulses de dépolarisation multiples pour mimer une stimulation tétanique dans des conditions plus physiologiques telles qu’utilisées dans la technique de courant imposé, et en présence de 50 mM de sodium extracellulaire, nous n’avons pas obtenu une entrée plus importante de Ca extracellulaire dans le myoplasme sous l’effet d’ISO. Les études sur la vitesse de libération de Ca dans le myoplasme ont indiqué une augmentation de ce paramètre par ISO. D’autre part, nos résultats indiquent aussi que l’effet d'ISO ne passe pas par une modification des propriétés d’activation des récepteurs à la dihydropyridine puisqu’aucune variation du mouvement de charges intra- membranaire n’a été observée. Ces résultats (dans les conditions où on considère que l’augmentation de l’entrée Ca dans le myoplasme aurait lieu pendant les stimulations électriques de la fibre exposée pendant 8 minutes avec 10 μM d’ISO), suggèrent que les propriétés de l’activation des canaux de libération de Ca du réticulum sarcoplasmique sont affectés sous l’effet d’ISO.

Despite concern that preterm infants receive inappropriate tactile and auditory stimulation because of early birth, few studies have explored the development of responsiveness to tactile and auditory stimulation prior to 40 weeks' postconceptional age. The present research traced longitudinally the development of responsiveness to tactile and auditory stimulation of 14 preterm infants born at 30 or less weeks' postconceptional age. The preterm sample was divided into three groups (well, moderately ill, and sick) to assess the effects of illness. All infants were assessed three times per week from 30 to 34 weeks' postconceptional age. Body movement, eye movement, heart rate, smiles, hand-to-mouth activity, and "avoidance" signals of grimaces, cries, yawns, and tongue protrusions were assessed in response to (a) auditory stimulation in the form of talking, (b) tactile stimulation in the form of touching/stroking, and (c) the combination of talking and touching. Further, these infants were assessed weekly for the development of neurological reflexes and responsiveness to the orientation items from the Brazelton Neonatal Behavioral Assessment Scale. When a pre-stimulus period was compared to a stimulus condition, preterm infants were found to respond to talking with significantly more eye movement; to touching with significantly more body movement; and to the combination of talking and touching with more body movement. Significant effects of illness were found when smiles, hand-to-mouth activity, and "avoidance" signals were assessed. During all the stimulation conditions the well infants had significantly more smiles and hand-to-mouth activity. During talking and the combination of talking and touching the sick infants also showed significantly more "avoidance" signals. Sick infants also performed less well than the well infants on the Brazelton orientation items and on some of the neurological exam items. The findings of this study suggested that responsiveness to social stimuli, talking and touching, develops quite early, even before the time of usual birth, and is minimally affected by illness. Behaviors shown by these infants are those likely to attract the caregiver's attention, suggesting that the preterm infant is capable of behaviors which will engage the caregiver and possibly serve as the roots of social behavior. / This thesis was digitized as part of a project begun in 2014 to increase the number of Duke psychology theses available online. The digitization project was spearheaded by Ciara Healy.

Contexte – La stimulation de la muqueuse trachéale peut provoquer une réponse défensive à type de toux. La finalité de cette réponse est la protection des voies aériennes via la clairance du mucus et des particules déposées au sein de l’arbre trachéo-bronchique. La stimulation de la muqueuse nasale est à l’origine de réponses défensives n’incluant toutefois pas la toux. La modulation de la toux suggère de possibles interactions centrales des afférences provenant de localisations anatomiques distinctes. Objectif – Déterminer si une stimulation trachéale mécanique discriminante est capable de provoquer une toux lors d’une apnée provoquée par l’instillation nasale d’eau distillée. Méthodes – Douze lapins anesthésiés et trachéotomisés ont été étudiés. Les stimulations trachéales mécaniques ont été réalisées dans 3 conditions : contrôle, après instillation nasale de sérum physiologique, et lors d’apnée suite à l’instillation d’eau distillée. Résultats – Les paramètres ventilatoires de références ne sont pas différents dans les 3 conditions. Un total de 171 stimulations trachéales a été réalisé. Lors de l’apnée, 81% des réponses sont des réflexes expiratoires et le pic de débit expiré est inférieur (p < 0.0001) à celui observé dans les conditions contrôle et sérum physiologique. L’incidence des réponses comprenant un réflexe de toux est plus faible (p < 0,0001) en cas d’instillation d’eau distillée que dans les 2 autres conditions.Conclusion – La stimulation nasale par l’eau distillée désensibilise les réflexes de défense respiratoire faisant suite à une stimulation trachéale mécanique / Context - Cough may be triggered by irritation of afferents located in the airway mucosa. Primary role is to expel inhaled foreign matter from the lungs or clear the airways of endogenous mucus. Stimulation of the nasal mucosa provokes defensive responses but not cough. The ‘cough center’ can be tuned by various afferent inputs, suggesting possible interactions at a central level of neural pathways originating from distant anatomical sites. Objective - The present study was designed to determine whether brief mechanical stimulation of the trachea could trigger cough during apnoea elicited by nasal instillation of water. Method - Twelve anesthetized, tracheotomized rabbits were studied. Mechanical stimulation of the trachea was performed under 3 conditions: baseline control, after instillation of saline into the nose and during apnoea following instillation of water. Results - Baseline breathing pattern did not differ between the 3 conditions. In a series of 171 stimulations, expiration reflex occurred in 81% of stimulations during apnoea with a significantly (p < 0.0001) lower peak expiratory flow than at baseline or during saline instillation. The incidence of responses comprising a cough reflex was also lower during water instillation than at either baseline or with saline (p < 0.0001). Conclusion - These results indicate that stimulation of nasal afferents with distilled water likely down-regulates cough

No description available.

This thesis proposes a multi-parameter implantable micro-stimulator system. By using wireless communication and the muli-parameter control, the infection caused by the wound could be avoided and various stimulation waveforms could be generated for different bio-medical applications. Besides, a graphic user interface (GUI) is implemented for the proposed micro-stimulator for the convenience of usage. Moreover, the in vitro experiments are carried out, where the neurons could be stimulated successfully. To reduce the system area caused by external capacitors required by traditional ASK demodulators, a C-less ASK demodulator is proposed in this thesis. A bias-based envelope detector and a Schmitt trigger are used for demodulation. Moreover, by enlarging the noise margin of the envelope detector, an all-MOS ASK demodulator is carried out such that no passive element is needed and the system area could be further reduced. Besides, two high sensitivity voltage-to-frequency (VFC) are proposed for the full duplex transmission. By using a voltage-to-current converter, a charge and discharge circuit, and an all-MOS voltage window comparator 1 (VWC1), a high sensitivity VFC1 is accomplished. Moreover, a linear VFC2 is also proposed by including a fast all-MOS voltage window comparator, VWC2. Finally, a wide range I/O buffer is proposed for the interface of the implantable micro-stimulator system. With the stacked PMOS and NMOS output stage and the dynamic gate bias generator, high voltage and low voltage signals (VDDH and VDDL) could be transmitted and received without any gate-oxide overstress and leakage currents.

Thesis (MPhil) -- AUT University, 2009. / Includes bibliographical references. Also held in print (xiv, 156 leaves : charts. ; 30 cm.) in the Archive at the City Campus (T 616.810645 ROS)

This master’s report collected the available literature regarding the multiple treatment approaches for oropharyngeal dysphagia and the efficacy of each approach in the remediation of swallowing deficits. A variety of traditional intervention techniques are described and their efficacy data is presented, as well as limitations and contraindications to intervention. Efficacy data for modern oropharyngeal dysphagia intervention techniques such as Vitalstim and E-stim is also presented, and the differences between the two techniques are discussed. Ethical decision-making in dysphagia treatment is also discussed. / text

Acid treatment, especially at high temperatures, is very challenging since HCl is really corrosive to the metal equipment. The use of HCl is associated with face dissolution, corrosion, and iron precipitation. Organic acids are weak and less corrosive than HCl but they have a limitation, which means that they can't be used at high concentrations. The next option would be chelating agents. Chelating agents are used in well stimulation, iron control during acidizing, and removal of inorganic scales. Chelates such as ethylenediaminetetraacetic acid (EDTA), N-(hydroxyethyl)-ethylenediaminetetraacetic acid (HEDTA), L- glutamic acid-N, N diacetic acid (GLDA), and nitrilotriacetic acid (NTA) are used in high-pressure/high-temperature oil and gas wells. GLDA is environmentally friendly, which makes it favorable. One of the concerns with these chelates is their thermal stability at high temperatures because if they degrade at high temperatures, they may lose their functionality. This study describes the thermal stability of these chelates, thermal degradation products, and some methods to improve their stability. The thermal stability is determined by measuring the concentration before and after heating using a complexo-metric titration utilizing FeCl₃ as a titrant. The degradation products are identified using Mass Spectrometry (MS). A series of experiments were run in the lab at varying temperatures (300 to 400°F) up to 12 hours, and the results shows chelates are not stable at temperatures greater than 350°F. Furthermore, chelates with two nitrogen atoms are more stable than those with one nitrogen atom. Iminodiacetic acid (IDA), acetic acid, and [alpha]-hydroxy acids are the decomposition products. There is a layer of black deposition after the chelates are heated, which is analyzed using Scanning Electron Microscope (SEM). Some coreflood tests are conducted using these degraded chelates to investigate the effect of these solid precipitates on the permeability of carbonate and sandstone cores. Increasing ionic strength and raising pH results in a higher thermal stability. Some salts such as, NH₄Cl, KCl, Csformate, and NaBr are added to chelate solutions to enhance stability.

An electro-mechanical device was developed to provide mechanical stimulation to cell populations for the purpose of studying how mechanical signals affect cell activity. The system can dynamically deform cubes of hydrogel seeded with cells by applying combinations of normal and shear forces to the faces of the hydrogel cube using plastic pads attached to the cube. The compact device was fabricated using rapid prototyping methods with ABS plastic and uses shape memory alloy actuator wires to generate the necessary forces. The actuator wires can be independently activated in sequence to create stimulation routines involving compression, tension and shear forces. All of the components can be sterilized and are corrosion resistant so they are not affected by the high humidity environment of a tissue incubator where cell stimulation studies are performed. The system fits inside a standard plastic lab container measuring 7 cm tall by 4 cm in diameter to maintain sterile conditions and hold the liquid culture medium required by the cells. During operation the hydrogel cube and the contact pads are submerged in the culture medium. The shape memory alloy actuators have been modeled in a two step process: 1) the electrothermal model, relating input electrical current to the wire temperature due to resistive heating and 2) the thermomechanical model relating the wire temperature to the wire strain and actuator stroke due to the shape memory effect. Testing was completed to validate the models and calibrate the shape memory alloy actuators. There was good agreement between the model predictions and the experimental results. For experiments with a hydrogel cube with sides measuring 1 cm, the system was capable of compressing the hydrogel cube up to 8 %, and generating shear strains of up to 7%. Tensile strains were much smaller at 0.9%. The dynamic deformations were applied at a frequency of 0.5 Hz. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-08-12 10:23:15.672

No description available.