La prise en charge des pathologies malformatives ou acquises dans le cadre pédiatrique a fait des progrès considérables au cours des dernières décennies. Cependant certaines prises en charge chirurgicale ne sont toujours pas optimales. C'est pourquoi la médecine régénérative représente une voie d'intérêt en chirurgie pédiatrique. Si différents types cellulaires ont été proposés, les cellules stromales issues du tissu adipeux sont une source intéressante de cellules pour l'ingénierie tissulaire car elles sont abondantes, faciles à prélever et sans problème éthique sous jacent, tout en conservant de multiples potentialités de différenciation. Si de nombreuses publications rapportent l'utilisation des ASC issues de donneurs adultes pour des protocoles précliniques ou cliniques, peu d'études se sont intéressées aux cellules issues de donneurs pédiatriques. L'objectif de ce travail était donc d'obtenir des données exhaustives sur les cellules d'enfant et notamment en fonction de leur âge. Outre les données in vivo, nous avons mis en place un protocole d'étude dans deux modèles murins. 77 enfants ont été prélevés de 1 g de tissu adipeux sous cutané selon les protocoles de collection biologique ASChild 1 et 2. Les cellules ont été séparées en 2 groupe (> et <à 1 an) et mis en culture afin d'étudier différents paramètres (taux d'extraction et de prolifération, phénotype, immunomodulation, formation de CFU-F, potentiel de différenciation en différentes lignées). Peu de différences ont pu être mis en évidence en fonction de l'âge si ce n'est un taux d'extraction cellulaire et une prolifération légèrement plus importante chez les donneurs les plus jeunes. De plus, une étude globale de l'expression génique en utilisant une technique de puce microarray n'a décelé une expression différentielle dans seulement 305 gènes (217 down et 8 up regulés) des pASC par rapport aux ASC adultes, sans différence notée entre les différents groupes d'âge. Afin d'évaluer le potentiel angiogénique des cellules pédiatriques (caractéristique bien connue des ASC), nous avons utilisé un modèle d'ischémie aigue de membre murin. Une ligature du pédicule fémoral était réalisée puis les cellules préalablement mises en culture étaient injectées au sein des loges musculaires de la patte (1 million de cellules dans 60 microl). 29 souris ont pu être traitées selon ces modalités par 6 prélèvements pédiatriques (2 du groupe 1, n=9 et 4 du groupe 2, n=20) et comparées à 30 souris injectées avec du Nacl. Le suivi longitudinal sur 14 jours a mis en évidence une amélioration de la microvascularisation grâce à l'étude microangiographique. D'autre part l'étude histologique a confirmé la viabilité des cellules au terme du suivi ainsi que la proximité des cellules avec les structures vasculaires. Afin de préciser le potentiel des pASC dans la cicatrisation cutanée, 4 prélèvements (2 groupes 1 et 2 groupes 2, n=20) ont été étudiés dans notre modèle murin de brûlure par ébouillantement et comparée à des souris contrôle (n=10). Les pASC permettent une amélioration des paramètres de cicatrisation (épithélialisation, contraction) au cours du suivi de 21 jours. Une amélioration de la vascularisation cutanée évaluée par laser doppler est observée en parallèle. Enfin les cellules ont pu être suivie pendant 21 jours in vivo et possèdent là encore une bonne viabilité au terme du suivi. Ce travail a permis de définir des paramètres essentiels dans l'optique d'une utilisation future des pASC dans la prise en charge des pathologies malformatives ou acquises de l'enfant. Néanmoins certains paramètres doivent être encore précisés comme le potentiel de tumorogénicité à long terme et le mode de délivrance le plus optimal. / Adipose derived mesenchymal stromal cells (ASC) are currently tested in regenerative medicine to promote tissue reconstruction after injury. In autologous purpose the possible loss of therapeutic function and cell properties during aging have been questioned in adult. To date no reliable information is available concerning ASC from pediatric patients and a better knowledge is required to intend their use for clinical applications. To address this issue, subcutaneous adipose tissue was collected from 27 donors aged 0-1 year and 50 donors aged 1-12 years and compared to adult ASC. Cells from the stromal vascular fraction (SVF) and subsequent cultured ASC were tested in vitro for their extraction and proliferation yield, phenotype, immunomodulation effect, CFU-F content, adipogenic, osteoblastic and angiogenic potentials. Only a slightly higher amount in cell number and proliferative rate were found. None of the other parameters was significantly different. In vivo, pediatric ASC induced an increase in microangiographic score in a mouse model of limb ischemia, even though improvement in vascular density was not significantly correlated to limb rescue. Finally mRNA analysis using microarray approach identified that only 305 genes were differentially expressed (217 down- and 88 up-regulated) in pediatric versus adult ASC, confirming that ASC from both groups of age shared very close intrinsic properties. Finally, we assessed the potentiality of pASC in a murine burn model, designed to cope with our daily practice as pediatric surgeons. We confirmed that cellular therapy based on pASC is effective as it improves early wound healing parameters (epithelialization, retraction). Laser Doppler analysis shows an higher local cutaneous blood flow with ASC than with NaCl. Moreover, we were able to follow the presence of the cells during 21 days. This work precises essential pASC features, which assessment was mandatory before considering a clinical use for malformative or acquired pathology during childhood. Nevertheless, precise understanding of ASC action mechanism needs to be completed as long term inocuity needs to be confirmed and mode of delivery to be adapted to a potential surgical use.

This study was directed at the pyrotechnic time delay compositions that are used in detonator assemblies. The objectives were to: --Investigate effective alternatives for the barium and lead-based oxidants currently used, maintaining the use of silicon as fuel --Develop easy to use, realistic measurement techniques for burn rates and shock tube ignitability --Determine the variables that affect burn rate, and --Evaluate alternative processing routes to facilitate intimate mixing of the component powders. Lead chromate and copper antimonite were found to be suitable oxidants for silicon in time delay compositions. They were ignitable by shock tubing, a relatively weak ignition source. The measured burn speeds for these systems showed a bimodal dependence on stoichiometry. Measured burn rates varied between 6-28 mm/s. Lead chromate is potentially a suitable alternative to the oxidant currently used in the medium burn rate commercial composition. It burns faster than copper antimonite. The latter is potentially a suitable replacement oxidant for the slow and medium compositions. Antimony trioxide-based compositions exhibited unreliable performance with respect to ignition with shock tubing. The addition of aluminium powder or fumed silica was found to reduce the burn rate. Increasing the silicon particle size (<3,5<font face="symbol">m</font>m) also decreased the burn speed for copper antimonite and lead chromate compositions. Addition of fumed silica improved the flow properties of the lead chromate, copper antimonite and antimony trioxide powders allowing for easier mixing. The silicon powder was found to react violently with water in alkaline solutions. This makes particle dispersion in a wet-mixing process problematic. / Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

The aim of this study was to determine whether coping strategies of police officers help moderate the outcome of burnout resulting from job stress. The nature of the job demands of police officers is such that they may experience high levels of stress. A convenience sample (N = 89: n Males = 58; n Female = 29) of police officers in police stations in the Eastern Cape was surveyed. The Maslach Burnout Inventory – General Survey, Police Stress Inventory and COPE questionnaire were administered. Results for all the participants indicate that when the occupational stressor Lack of Resources occurs police officers implement Avoidance Coping (COPE) as a strategy, which leads to the experience of Exhaustion. Results also indicate that police officers use Active Coping, Cognitive Coping and Turning to Religion as means of moderating the stress-burnout relationship. Results also show that the coping strategy Avoidance Coping, used by male officers lead to Cynicism. When female police officers experience Job Demands and a Lack of Resources they make use of Seeking Emotional Support as a coping strategy. Male police officers were shown to make use of Active Coping as a strategy to regulate the stress-burnout relationship while female police officers implemented Active Coping and Turning to Religion to act as a buffer between job stress and burnout.

This research examines the level of stress experienced by social workers employed in a locked mental health hospital. A comparative analysis was completed measuring the level of stress associated with the type of unit: acute or chronic.

Burnout among primary care providers, which include physicians, nurse practitioners, and physician assistants, can negatively impact patients, providers, and organizations. Researchers have reported that up to 37% of primary care physicians experience burnout, yet the prevalence, predictors, and outcomes associated with primary care nurse practitioner burnout remains unknown. Since 69% of nurse practitioners provide primary care to patients, this dissertation investigates the predictors and outcomes associated with primary care nurse practitioner burnout. A history of burnout as well as the importance of investigating burnout among primary care nurse practitioners are discussed in the first chapter. A systematic review of the predictors and outcomes of primary care provider burnout is discussed in the second chapter. The third chapter describes a cross-sectional study conducted among 396 primary care nurse practitioners from New Jersey and Pennsylvania, which investigated whether the practice environment is associated with nurse practitioner burnout. The fourth chapter describes a cross-sectional study investigating whether the use of multifunctional electronic health records is associated with primary care nurse practitioner burnout. The fifth chapter includes another cross-sectional study examining the relationship between primary care nurse practitioner burnout and quality of care, and if the practice environment moderates the relationship between burnout and quality of care. Finally, the sixth concluding chapter summarizes the findings from chapters two to five and provides recommendations for future research, practice, and policy.

Reed canarygrass (Phalaris arundinacea) is a grass species that can dominate wet meadow plant communities. This study investigated if grazing by cattle on restored wet meadows suppresses reed canarygrass, thereby promoting the restored plant community. This study was conducted at two locations in northwest Minnesota. Management practices used were a patch-burn grazing treatment and a four-pasture high intensity-short duration grazing rotation. A pretreatment survey was conducted before grazing followed by annual surveys every five years after grazing. Both treatments reduced reed canarygrass canopy cover by 49 percent compared to non-grazed control sites. Grazed patches were moving towards a Carex dominated community. The community not invaded with reed canarygrass had similar native species richness at the end of the experiment in the rotational grazing treatment, and improved plant richness in the patch-burn grazing treatment. This study demonstrates grazing reduces cover of reed canarygrass, while maintaining or increasing native plant species richness.

The purpose of this study was to determine what job responsibilities Extension 4-H youth development professionals (n = 241) chose to spend their work time doing and how the workload related to their job satisfaction and burnout. They were asked to rank order seven common, predetermined job responsibilities, based on the 4-H Professional, Research, Knowledge, and Competencies ( 4-H PRKC), and to identify their level of job satisfaction and burnout. The study utilized quantitative methods for gathering data from 4-H youth development Extension professionals from 6 land-grant universities. Over the past 25 years, there has been an increase in research investigating burnout and job satisfaction. Burnout is a serious issue that can lead to decreased productivity for the employee and increased costs for the employer. Finding the connections among burnout, job satisfaction, and work environment is important to help reduce problems, including work overload. Based on the previous research on workload, burnout, and job satisfaction, 4-H youth development professionals are prime candidates for experiencing low job satisfaction and increased burnout, which may lead to professionals leaving the organization early. To determine the workload, 4-H youth development professionals were asked to rank seven job responsibilities for each of the domains that are common to the youth development profession. The job responsibility that had the lowest mean of any from the six domains was #1 "using volunteer committees" in the volunteerism domain, with 71.9% of the respondents ranking it as one of the top two job responsibilities within the domain. Determining job satisfaction related to the individual job responsibilities was the first measurement used in identifying the level of job satisfaction in the survey. The youth development domain's job responsibility #6 "develop programs to practice life skills" provided the respondents the greatest degree of job satisfaction (M = 1.93, SD= 0.72) of any of the responsibilities with the six 4-H PRKC domains. The second instrument used to assess job satisfaction for 4-H youth development professionals was the Job Satisfaction Survey (JSS), in which the mean score was 3.72 (SD= 0. 79). The third and final measurement used to determine job satisfaction was the self-reported overall level of job satisfaction. The mean for the self-reported overall job satisfaction was 2.20 (SD= 0.83). The greatest degree of burnout (M = 3 .21, SD= 1.26) within any of the domains was in the youth development domain with job responsibility #7 "dealing with conflict management." This job responsibility also indicated a negative relationship between the workload rank score and job responsibility burnout (r = -0.250). The overall mean for the Burnout survey was 3.84 (SD= 0.86). The greatest burnout came from the work within the youth development domain. The 4-H youth development professionals reported feeling very little overall burnout related to their job. The overall self-reported mean for burnout was 2.75 (SD=1.17). They also reported being satisfied with their current job (M= 2.20, SD= 0.83).

The purpose of this study was to determine the extent to which family therapy students used their spiritual and/or religious beliefs as a resource for preventing clinical burnout and in their self-care practices. Additionally, this study sought to explore the specific ways or strategies that students used their spiritual beliefs in their personal and professional lives. Participants were master’s and doctoral students from programs accredited by the Commission on the Accreditation of Marriage and Family Therapy (COAMFTE). A total of 341 students participated in the study. The results demonstrated that the majority of students reported that they used their spiritual and/or religious beliefs as an important resource for preventing burnout and for self-care. Additionally, thematic analysis revealed several different themes regarding the specific spiritual practices participants used within their personal and professional lives.

This work deals with the thermal load during cut-off grinding of high-strength bearing rings. Linear cut-off operations lead to a high rise in temperature over the cutting process. These leads, together with the limited material volume, in a heat build-up and the resulting grinding burn. The aim of this work was to prevent this head build-up by using two-axis cut-off operations. Therefore, known methods were theoretically considered and from this, alternative two-axis strategies were determined. For testing, experiments were carried out on a test set-up developed in this work. The tests showed that the two-axis strategies lead to significantly reduced temperatures, as well as non-grinding burn and partially burr-free cutting surfaces. However, the two-axis methods lead to increased process times, which is why approaches for their optimization have been discussed.

The purpose of this study was to investigate the role of self-efficacy enhancement in building pre-service teacher resilience to prevent symptoms of burn-out in Swaziland; how engaging in reflective practices can act as a protective factor. Not much research focuses on pre-service teacher burn-out and how to mitigate its effects, and this creates a gap that this study sought to address. Through the interpretivist perspective, and employing participatory action research (PAR) and some elements of pre-test, post test design, seven pre-service teachers who were doing their final year of a three year teacher’s diploma programme; four males and three females were engaged in the study. Data were collected by using the resilience scale questionnaire, participants’ reflective journals, researcher’s diary and transcribed recordings from a focus group interview. Three themes emerged; (1) that pre-service teachers in Swaziland do experience symptoms of burn-out during teaching practice. Seven risk factors that contribute to the experience of burn-out were cited by participants; learners’ behavioural issues, heavy workloads, demanding supervisors, lack of support from colleagues, teaching learners who are high achievers, feelings of inadequacy and lack of prioritising. (2) Pre-service teachers were able to draw strength and possibly avert burn-out by mobilising external and internal protective sources. (3) Reflective practices proved to be a viable intervention that enhanced pre-service teachers’ self-efficacy and helped promote resilient coping. Future research might look into other factors that predispose pre-service teachers to stress and how reflective practices may be infused in the curriculum for pre-service education. / Dissertation (MEd)--University of Pretoria, 2017. / Humanities Education / MEd / Unrestricted