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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A comparison of inspiratory muscle fatigue following maximal exercise in moderately trained males and females

Ozkaplan, Atila. January 2004 (has links)
Thesis (M.S.)--University of British Columbia, 2004. / Includes bibliographical references (leaves 88-98). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.
12

Design verification of a diaphragm wall with steel piles /

Sedey, Jeffrey Scott, January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 137-140). Also available via the Internet.
13

A comparison of inspiratory muscle fatigue following maximal exercise in moderately trained males and females

Ozkaplan, Atila. January 2004 (has links)
Thesis (M.S.)--University of British Columbia, 2004. / Includes bibliographical references (leaves 88-98).
14

Fatigue and rest of the hamster diaphragm

Reid, Wendy Darlene January 1988 (has links)
Decreased respiratory muscle strength and/or excessive loads imposed on the respiratory muscles by disease may result in respiratory muscle fatigue and ventilatory failure. Once the respiratory muscles fatigue, the only treatment is rest by mechanical ventilation. However, no one has yet determined the best protocol of rest. The purpose of these studies was to develop an animal model in the hamster in order to examine the time course of recovery following fatigue of the diaphragm and specifically, to test whether mechanical ventilation or spontaneous unloaded breathing was a better mode for functional recovery. The studies required the initial development of an anesthetic regimen which produced minimal respiratory depression in the hamster. A new method of stimulating the diaphragm in small animals was developed by apposing plate electrodes directly against the diaphragm. The validity of this technique was examined and comparison of the mechanical and electrophysiological response to that of phrenic nerve stimulation were similar at maximal stimulation. The histological characteristics of the normal hamster diaphragm were determined for fibre type proportions and sizes, oxidative capacity and glycogen levels in the costal and crural regions of this muscle. The examination revealed three distinct areas of the diaphragm with different histological features: the abdominal surface of the crural region, the thoracic surface of the crural region and the sternal and costal region. Diaphragmatic fatigue was induced in vivo by repetitive electrical stimulation which resulted in both high and low frequency fatigue. The fatigue stimulus also produced muscle fibre damage, primarily along the abdominal surface of the diaphragm over the electrodes, and glycogen depletion in the type lib fibres. Rest by continuous mechanical ventilation resulted in recovery of high frequency fatigue in the hamster diaphragm whereas rest by spontaneous unloaded breathing resulted in no recovery. Sham fatigue groups rested by either mechanical ventilation or spontaneous breathing demonstrated progressive deterioration in transdiaphragmatic pressure throughout the rest period. Decreased muscle fibre damage but increased inflammation and glycogen depletion was demonstrated in all four fatigue/sham fatigue and rest groups compared to that demonstrated by the fatigue/sham fatigue only groups. The results suggest that passive rest by continuous mechanical ventilation promotes recovery following fatigue induced by electrical stimulation. Additional factors such as prolonged fasting, loads imposed on the diaphragm by the plate electrode apparatus, positive pressure ventilation, and cumulative effects of intraperitoneal urethane likely contributed to the progressive deterioration of diaphragmatic function demonstrated in the animals of the two sham groups rested by either spontaneous breathing or mechanical ventilation, and confounded the results shown by the two fatigue groups rested by either spontaneous breathing or mechanical ventilation. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate
15

A technique to study diaphragmatic fatigue using spectral changes of the electromyogram in health and emphysema /

Abolmolouki, Hossein, January 1981 (has links)
No description available.
16

The function of the human diaphragm as a volume pump and measurement of its efficiency

Singh, Bhajan January 2004 (has links)
[Truncated abstract] The function of the diaphragm as a volume pump has not been adequately evaluated because there are no accurate methods to measure the volume displaced by diaphragm motion (ΔVdi). As a consequence, the work done, power output and efficiency of the diaphragm have not been measured. Efficiency of the diaphragm could be measured by relating the power output of the diaphragm to its neural activation. The aims of this thesis were to (a) develop a new biplanar radiographic method to measure ΔVdi and use this to evaluate the effect of costophrenic fibrosis and emphysema on ΔVdi, (b) develop a new fluoroscopic method to enable breath-by-breath measurements of ΔVdi, (c) evaluate a method for quantifying neural activation of the diaphragm, and (d) combine measurements of transdiaphragmatic pressure, ΔVdi, inspiratory duration and neural activation of the diaphragm to quantify the neuromechanical efficiency of the diaphragm
17

The relationship between diaphragm thickness, diaphragm strength and diaphragm endurance in young, healthy individuals

Orrey, Samantha Taylor 04 1900 (has links)
Thesis (MScPhysio)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Introduction: In the intensive care unit population, approximately 40% of patients require mechanical ventilation and 20-25% of these patients will encounter difficulties in the discontinuation of mechanical ventilation. As mechanical ventilation affects the diaphragm, a better understanding of the structural and functional changes of the diaphragm is warranted. Method: A scoping review was done to determine whether a relationship between diaphragm thickness, diaphragm strength and diaphragm endurance had been established. Seven databases were searched using a specific search strategy. Papers were identified based on pre-defined inclusion criteria. Data was extracted by the primary investigator (PI) into a self-developed excel spreadsheet. Criteria were developed for a more focused review to inform the planning of a primary study. The primary study investigated the relationship between diaphragm thickness, diaphragm strength and diaphragm endurance in young, healthy individuals. A sample of convenience was used; included healthy individuals (18-24); three activity-levels (sedentary; endurance- and strength related sporting activities); stratified for gender and BMI. Measurements included: Sonographic measurement of diaphragm thickness; mouth pressure manometer measurements for diaphragmatic strength; and fatigue resistance index as a measure of endurance. Participants were instructed to breathe through a pressure threshold device at 60% of PImax until task failure. The fatigue resistance index was calculated as PImax final/PImax initial. Intra-rater reliability was established and testing procedures standardised a priori. Results: 405 full texts were retrieved and assessed for inclusion into the review. Papers identified the evaluation of diaphragm function in a variety of populations. 23 papers were included in the focused review. Six papers were published on diaphragm thickness, six on diaphragm strength and eleven on diaphragm endurance. No papers identified the correlation between diaphragm thickness, diaphragm strength and diaphragm endurance. 55 subjects, males and females, were recruited for the primary study. Groups were similar at baseline with regards to gender, age and BMI. The mean age of the sample was 21.16 years (SD = 1.55), with a mean body mass index (BMI) of 25.43 kg/m2 (SD = 3.70). A moderate positive correlation was established between diaphragm thickness and diaphragm strength measurements (r = 0.52; r2 = 0.27; p < 0.01). Diaphragm thickness was not correlated with diaphragm endurance (r = -0.15; r2 = 0.02; p = 0.29). No relationship was found between the strength of the diaphragm and the endurance of the diaphragm (r= -0.19; r2 = 0.04; p= 0.16). Conclusion: Guidelines for the measurement of diaphragm function do exist, but they are not adhered to by the majority of studies. Study procedures are inconsistently reported and this may affect the reproducibility of techniques in future studies. We further conclude that a correlation exists between diaphragm thickness and diaphragm strength. The use of ultrasound to measure diaphragm thickness proved to be a reliable technology and gave a moderate indication of the strength of the diaphragm. This technology may help clinicians to detect and monitor dysfunction of the diaphragm in the early stages of admission to the acute setting. / AFRIKAANSE OPSOMMING: Inleiding: Ongeveer 40% van pasiente wat in intensiewe sorgeenheid behandel word, benodig intubasie en meganiese ventilasie. Tot 25% van hierdie pasiënte sal probleme ondervind in die staking van meganiese ventilasie. Meganiese ventilasie beïnvloed die diafragma, daarom word n beter begrip van die strukturele en funksionele veranderinge van die diafragma benodig. Metode: 'n Literatuur oorsig is gedoen om te bepaal of daar 'n verhouding bestaan tussen die dikte, krag en uithouvermoë van die diafragma. Sewe databasisse is deurgesoek aan die hand van spesifieke databasis gedefinieerde soektog strategie. Relevante artikels is geïdentifiseer aan die hand van pre-gedefinieerde insluiting kriteria. Data is onttrek en in ‘n self-ontwikkelde datablad opgesom deur die primêre ondersoeker (PI). Hierdie inligting is gebruik in die beplanning van ‘n primêre studie. Die doel van die primêre studie was om die verhouding tussen die diafragma dikte, krag en uithouvermoë in jong, gesonde individue te ondersoek. ‘n Gerieflikheids steekproef is gebruik; insluitend gesonde individue (18-24); drie aktiwiteits vlakke (passief; uithouvermoë- en krag verwante sportaktiwiteite) en breë spektrum vir geslag en ligaamsbou (BMI). Metings ingesluit: sonografiese meting van die diafragma se dikte; monddruk manometer metings vir diafragmatiese krag en ‘n moegheid/weerstand indeks as maatstaf van diafragmatiese uithouvermoë. Deelnemers is opdrag gegee om asem te haal deur toestel met druk maksimum gestel 60% van PImax, tot mislukking. Die moegheid/weerstand indeks is bereken as PImax finale / PImax oorspronlik. Intra-meter betroubaarheid is bepaal en toets prosedures is gestandaardiseer voordat data ingesamel is. Resultate: 405 vol teks artikels is uitgelig vir insluiting in die literatuur oorsig. Diafragmatiese funksie is ge-evalueer in 'n verskeidenheid bevolkings. Drie en twintig artikels is in die finale oorsig ingesluit. Ses artikels wat diafragma dikte evalueer, ses wat diafragmatiese krag evalueer en elf wat die diafragma se uithouvermoë evalueer is ingesluit in die oorsig. Geen van die artikels uitgelig het ‘n ooreenkoms tussen diafragma dikte, diafragma krag en diafragma uithouvermoë geïdentifiseer nie. 55 deelnemers is gewerf vir die primêre studie. Groepe was soortgelyk by basislyn met betrekking tot geslag, ouderdom en BMI. Die gemiddelde ouderdom van die toetsgroep was 21.16 jaar (SD=1.55), met 'n gemiddelde BMI van 25.43 kg/m2 (SD = 3.70). ‘n Middelmatige positiewe verhouding is waargeneem tussen diafragma dikte en krag (r = 0.52; r2 = 0.27; p < 0.01). Geen verhouding is gevind tussen diafragma dikte en uithouvermoë nie (r= -0.15; r2 = 0.02; p = 0.29). Daar is ook geen verhouding waargeneem tussen diafragma krag en diafragma uithouvermoë nie. (r= 0.19; r2 = 0.04; p = 0.16). Gevolgtrekking: Daar bestaan wel riglyne vir die meting van die diafragma se funksie, maar in die meerderheid van studies word dit nie nagekom nie. Studie prosedures is nie konsekwent weergegee nie en dit kan die resultate van tegnieke beinvloed in toekomende studies. ‘n Matige sterk verhouding is waargeneem tussen diafragmatiese dikte en krag. Die gebruik van ultraklank om die diafragma se dikte te meet is betroubare tegnologie en kan n redelike aanduiding gee oor die krag van die diafragma. Hierdie tegnologie kan praktisyne help om enige disfunksie van die diafragma te identifiseer en te monitor in die vroeë stadiums van toelating tot die akute omgewing.
18

Improvements to the Design of a Flexible Diaphragm for use in Pressure Wave Generators for Cryogenic Refrigeration Systems.

Hamilton, Kent Anthony January 2013 (has links)
Low cost cryocoolers suitable for long term use in industrial environments are required for superconducting technologies to be competitive with copper based devices in real world applications. Industrial Research Limited is developing such cryocoolers, which use metal diaphragm based pressure wave generators to convert electrical energy to the gas volume displacement required. This project explores methods of increasing the volume displacement provided by the diaphragms while ensuring the components stay within the acceptable material limits. Various alternative diaphragm shapes are tested against the currently used shape through finite element analysis. In addition to testing alternative diaphragm shapes, each shape’s dimensions are optimised. It is concluded the currently used design can be improved by offsetting the piston rest position and slightly reducing the piston diameter. A more detailed analysis is carried out of the bend radii created during fabrication of the diaphragm, and physical testing is performed to verify unexpected calculated stress concentrations. High stresses are observed, however it is concluded unmodelled material features have a large effect on the final stress distribution. It is recommended advantageous shape changes calculated in the first part of the work be trialled to increase the efficiency of the cryocooler, and that investigation of the material behaviour during commissioning of the pressure wave generator be carried out to better understand the operational limits of the diaphragms.
19

Effect of abdominal binding on cardiorespiratory function in paralympic athletes with cervical spinal cord injury

West, Christopher Roy January 2011 (has links)
Spinal cord injury (SCI) causes a lesion-dependent impairment in cardiorespiratory function that may limit exercise capacity. The aims of this thesis were to describe cardiorespiratory function in highly-trained athletes with low-cervical SCI, and to investigate whether abdominal binding enhances cardiorespiratory function at rest and during exercise in this population. Using body plethysmography, bilateral phrenic nerve stimulation and transthoracic ultrasound, it was demonstrated that Paralympic athletes with cervical SCI exhibit a restrictive pulmonary defect, impaired diaphragm and expiratory muscle function, and low left ventricular mass and ejection fraction compared to able-bodied controls. Using the same methods, it was shown that abdominal binding improves resting cardiorespiratory function by reducing operating lung volumes, and increasing vital capacity, twitch transdiaphragmatic pressure, expiratory muscle strength and cardiac output. A further finding was a positive relationship between binder tightness and cardiorespiratory function. During a field-based assessment of fitness, abdominal binding reduced the time taken to complete an acceleration/deceleration test and increased the distance covered during a repeated maximal 4-min push test. During laboratory-based incremental wheelchair propulsion, abdominal binding altered breathing mechanics by reducing operating lung volumes and attenuating the rise in the pressure-time index of the diaphragm. Furthermore, abdominal binding increased peak oxygen uptake and reduced peak blood lactate concentration, despite no change in peak work rate. Peak oxygen uptake in the laboratory was related to the distance covered during the maximal 4-min push, suggesting that the improvement in field-based performance with binding was due to an improvement in aerobic capacity. In conclusion, this thesis demonstrates that abdominal binding significantly enhances cardiorespiratory function at rest, improves exercise performance in the field, and improves operating lung volumes, breathing mechanics and peak oxygen uptake during incremental treadmill exercise. Thus, abdominal binding provides a simple, easy-to-use tool that can be used to enhance cardiorespiratory function at rest and during exercise in highly-trained athletes with cervical SCI.
20

Formulation of rigid diaphragm analysis spreadsheet by stiffness method

Maldonado, Alfredo Raamsett 19 April 2013 (has links)
This report is the documentation for a stiffness formulation to perform rigid diaphragm analysis for wood structures subjected to wind loads. Traditionally, rigid diaphragm analysis has been performed using a vaguely-defined superposition approach; however, this report details a more rational stiffness approach to solving for forces placed on walls resulting from a rigid diaphragm, and its implementation is via a simple spreadsheet application. In addition to the formulation of the spreadsheet, the report contains a User’s Guide and examples of the spreadsheet’s use. The purpose of the spreadsheet is not as a replacement to more sophisticated and comprehensive finite element analysis software, but as a tool to aid designers who practice engineering and may not have access to such software. In general, the application is developed for wood diaphragms as will be noted by references to wood-related codes. However, much of the approach may be used for diaphragms constructed with other materials as well. / text

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