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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.
631

Occupational exposure to radon in a South African platinum mine / M. Schoonhoven.

Schoonhoven, Martin January 2012 (has links)
Background: The Platinum mining operations in South Africa mining platinum containing ore from areas where variable amounts of uranium are found, leading to the possibility of occupational exposure to the radioactive disintegration products of Uranium-238 and in particular the gas Radon-222. No scientific data is available for occupational exposure to Radon-222 in South African platinum mining operations. Objective: To determine the risk of occupational exposure to the radioactive disintegration products of naturally occurring Radon-222 gas in a South African platinum mine. Design: Quantitative sampling (personal and static) to establish baseline data on exposure to radioactive disintegration products of naturally occurring Radon-222 gas in a underground South African platinum mine. Setting: The Bafokeng Rasimone platinum mine located 30 km North West of Rustenburg in the Bushveld complex in the North West Province of South Africa. Study subjects: One hundred and seventy four potentially highest exposed underground employees and one hundred and twelve static underground samples were sampled. Method: Personal and area samples were taken on selected employees and in locations using RGM samplers using CR-39 plastic as a detection medium. Employees were selected to sample the highest exposed occupations and static samples were located to sample returning air from levels underneath the sampling point before it is exhausted to the above ground atmosphere. After analysis by an accredited laboratory, the results were converted to exposure following the National Council on Radiation Protection-78 methodology. Main outcome measures: Quantify the relative risks of potentially highest exposed employee`s exposure to the radioactive disintegration products of naturally occurring Radon-222 gas in underground working areas in milliSievert per year. Results: The mean reference background exposure averaged 0.6168 mSv/a with underground personal exposure averaging 0.6808 mSv/a, and underground static exposure averaging 0.8726 mSv/a. These values are substantially below the 50 mSv/a Occupational Exposure Limit, and only pose a slightly elevated risk for the development of lung cancer above the normal back-ground exposure. Mining Team leaders and rock drill operators were identified as the potentially highest exposed employees due to the close proximity to the working face, large amounts of time spent close to the working face and the lower ventilation volumes at the working face, with Team leaders having the highest exposure of the sampled occupations with a average of 1.16 mSv/a. Conclusions: Occupational exposure to radioactive disintegration products of naturally occurring Radon-222 gas in the underground air of a South African platinum mine does not pose a significant risk to the health of employees working in the platinum mine. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.
632

Occupational exposure to radon in a South African platinum mine / M. Schoonhoven.

Schoonhoven, Martin January 2012 (has links)
Background: The Platinum mining operations in South Africa mining platinum containing ore from areas where variable amounts of uranium are found, leading to the possibility of occupational exposure to the radioactive disintegration products of Uranium-238 and in particular the gas Radon-222. No scientific data is available for occupational exposure to Radon-222 in South African platinum mining operations. Objective: To determine the risk of occupational exposure to the radioactive disintegration products of naturally occurring Radon-222 gas in a South African platinum mine. Design: Quantitative sampling (personal and static) to establish baseline data on exposure to radioactive disintegration products of naturally occurring Radon-222 gas in a underground South African platinum mine. Setting: The Bafokeng Rasimone platinum mine located 30 km North West of Rustenburg in the Bushveld complex in the North West Province of South Africa. Study subjects: One hundred and seventy four potentially highest exposed underground employees and one hundred and twelve static underground samples were sampled. Method: Personal and area samples were taken on selected employees and in locations using RGM samplers using CR-39 plastic as a detection medium. Employees were selected to sample the highest exposed occupations and static samples were located to sample returning air from levels underneath the sampling point before it is exhausted to the above ground atmosphere. After analysis by an accredited laboratory, the results were converted to exposure following the National Council on Radiation Protection-78 methodology. Main outcome measures: Quantify the relative risks of potentially highest exposed employee`s exposure to the radioactive disintegration products of naturally occurring Radon-222 gas in underground working areas in milliSievert per year. Results: The mean reference background exposure averaged 0.6168 mSv/a with underground personal exposure averaging 0.6808 mSv/a, and underground static exposure averaging 0.8726 mSv/a. These values are substantially below the 50 mSv/a Occupational Exposure Limit, and only pose a slightly elevated risk for the development of lung cancer above the normal back-ground exposure. Mining Team leaders and rock drill operators were identified as the potentially highest exposed employees due to the close proximity to the working face, large amounts of time spent close to the working face and the lower ventilation volumes at the working face, with Team leaders having the highest exposure of the sampled occupations with a average of 1.16 mSv/a. Conclusions: Occupational exposure to radioactive disintegration products of naturally occurring Radon-222 gas in the underground air of a South African platinum mine does not pose a significant risk to the health of employees working in the platinum mine. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.
633

Balancing efficiencies and tradeoffs in epidemiological field studies : evaluating EMG exposure assessment for low back injury risk factors in heavy industry

Trask, Catherine Mary 11 1900 (has links)
In order to investigate the etiology of and evaluate interventions for work-related back injuries, researchers need efficient, accurate occupational exposure assessment methods suitable for large samples. The chapters in this thesis examine critical decisions using electromyography (EMG): How should exposure be measured? For what duration? Who should be measured, and how many times? Low-back EMG, or muscle activity data, was collected during 138 full-shift field measurements over 30 different job titles at 50 different worksites in 5 heavy industries: forestry, transportation, wood products, construction, and warehousing. Observations and self-reports of posture, manual materials handling (MMH), and driving exposures were collected concurrently. 1) Variability of EMG calibration measurements was investigated on right/left sides, multiple trials, 4 positions, and pre/post-shift. Position accounts for the majority of explained variability; there is little to gain by measuring multiple trials or pre- and post-shift, but measuring both sides and multiple positions is worthwhile. 2) Observation and self-report data were easier to collect and cheaper than the EMG direct measure. Costs and successful field performance need to be weighed against the added data detail when making choices about exposure assessment techniques for epidemiological studies. 3) Observed and self-reported exposures were used to predict EMG exposure metrics using mixed multiple linear regression models. Regression models using observed variables predicted 43-50% of the variability in the EMG metrics, while self-reported variables predicted 21%-36%. The observation exposure model provides a low-cost alternative to direct measurement. The self-reported exposure model should be considered with more caution. 4) Full-shift EMG data was resampled for 4, 2, and 1 hour, and for 10 and 2 minute durations to determine the optimal sampling duration. Bias was consistently low, but shorter durations had higher absolute error, percentage error, and limits of agreement. Durations of 4 and 2 hours may be acceptable but those less than 1 hour had large errors. 5) Components of EMG variance were calculated between- and within-subject, and between- industry, company, job, and post hoc grouping. Resolution, contrast, and exposure-response relationship attenuation were calculated for each grouping scheme. The post hoc scheme had the highest contrast and lowest resolution.
634

Occupational and environmental aspects on the aetiology of rheumatoid arthritis /

Reckner Olsson, Åsa January 2003 (has links) (PDF)
Diss. (sammanfattning) Linköping : Univ., 2003. / Härtill 5 uppsatser.
635

Cancer risks and immunological effects in agriculture /

Settimi Dionisi, Laura January 2003 (has links) (PDF)
Diss. (sammanfattning) Linköping : Univ., 2003. / Härtill 6 uppsatser.
636

Hearing impairment and deafness : genetic and environmental factors - interactions - consequences : a clinical audiological approach /

Carlsson, Per-Inge, January 2005 (has links)
Diss. (sammanfattning) Örebro : Örebro universitet, 2005. / Härtill 5 uppsatser.
637

Dissociation of hexavalent chromium from primer paint particles into simulated mucus fluid /

Moran, Michael Patrick. January 2005 (has links) (PDF)
Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).
638

Produktplacering i fillm : ur konsumentens perspektiv

Al Hajderi, Dahlia January 2018 (has links)
Syfte: Att få en inblick på konsumenters attityder till produktplacering och hur produktplacering influerar konsumenten utifrån två faktorer, varumärkeskännedom och exponering. Metod: Denna studie har genomförts genom en kvantitativ metod. En enkätundersökning har varit till stöd vid insamling av empiri där ett filmklipp har varit i fokus för enkäten. Slutsats: Slutsatsen med denna studie är att produktplacering uppfattas positivt och beroende på vilken exponeringsmetod eller tidigare varumärkeskännedom konsumenten har så kan det influera konsumenterna, vilket innebär att det antingen kan leda till ett köp eller inte beroende på vilken attityd konsumenten har. / Purpose: To get an insight into consumer attitudes toward product placement and how product placement influences the consumer based on two factors, brand awareness and exposure. Method: This study has been conducted through a quantitative method. A survey has been in support of the gathering of empire where a movie clip has been the focus of the survey. Conclusion: The conclusion of this study is that product placement is perceived positively and depending on the exposure method or previous brand awareness the consumer has, it may affect consumers, which means that it can either lead to a purchase or not depending on the attitude of the consumer.
639

Factors contributing to nurses' poor utilization of HIV-related post exposure prophylaxis at a selected region in Swaziland

Dlamini, Patience Nokthula 12 1900 (has links)
Nurses are prone to occupational hazards while carrying out their professional duties. The HIV-related post exposure prophylaxis is recommended for health workers who prick themselves accidentally with needles that have been used on clients. The taking of antiretroviral drugs after encountering needle stick injury has been documented by medical scientists as relatively successful in preventing sero-conversion and decreasing the likelihood of contracting HIV infection. However, some of the nurses are reluctant to implement this programme and yet they have been exposed to needle stick prick. The purpose of this study was to investigate factors contributing to nurses’ poor utilization of HIV-related post exposure prophylaxis (PEP) at a selected region in Swaziland. The study was conducted in one hospital setting and one public health unit. A quantitative research design using an exploratory, descriptive cross sectional survey was used for this study. A census sample size of 200 participants was obtained from a group of nurses working in the government hospital and public health units. Using self-administered questionnaires, quantitative data was obtained and analysed using the Statistical package for social sciences (SPSS) version 23 software computer program. The study findings revealed that though majority of nurses (65%) are knowledgeable about PEP, its importance and operational policies and guidelines, this knowledge level was not transferred to influence the utilization of PEP as only 38% (n=75) reported utilizing PEP. Factors identified as causes of lower levels of PEP service utilization among respondents included fear of undergoing pre-prophylaxis procedures like HIV testing and counselling, and consequences thereof which include stigma, challenges of adherence and dealing with medication side effects. Based on these findings the researcher recommends strengthening of staff development programs offered to nurses with focus on preventive measures against occupational exposure to HIV and AIDS through use of PEP. Institutional responsibility to ensure that PEP policies and guidelines are available and known by all new health personnel during induction and practicing nurses throughout their employment. / Health Studies / M.A. (Nursing Science)
640

Avaliação da inervação entérica e análise proteômica do intestino delgado de ratos expostos à dose aguda ou crônica de fluoreto / Evaluation of enteric innervation and proteomic analysis of the small intestine of rats exposed to acute or chronic fluoride dose

Carina Guimarães de Souza Melo 03 December 2015 (has links)
O trato gastrointestinal (TGI) é a principal rota de exposição ao fluoreto (F) e o seu mais importante sítio de absorção. Acredita-se que a toxicidade do F comprometa a fisiologia do intestino, devido à relevante sintomatologia gastrointestinal relatada em consequência da exposição excessiva ao F. A função intestinal é controlada por uma complexa rede neuronal interligada e incorporada à parede deste órgão, denominada Sistema Nervoso Entérico (SNE). Embora os efeitos tóxicos do F sobre o Sistema Nervoso Central sejam descritos na literatura, não há estudos relacionados à sua toxicidade sobre o SNE. Neste estudo realizado em ratos, foi avaliado o efeito da exposição aguda ou crônica ao F, sobre a população geral de neurônios entéricos e sobre as subpopulações que expressam os principais neurotransmissores entéricos: Acetilcolina (ACh), Óxido Nítrico (NO), Peptídeo Vasoativo Intestinal (VIP), Peptídeo Relacionado ao Gene da Calcitonina (CGRP) e Substância P (SP). Os animais foram divididos em 5 grupos: 3 destinados à exposição crônica (0 ppm, 10 ppm ou 50 ppm de F na água de beber) e 2 à exposição aguda (0 ou 25 mgF/Kg por gavagem gástrica). Foram coletados os 3 segmentos do intestino delgado (duodeno, jejuno e íleo) e processados para a detecção da HuC/D, ChAT, nNOS, VIP, CGRP e SP, através de técnicas de imunofluorescência, no plexo mioentérico. Foram obtidas imagens para a realização da análise quantitativa dos neurônios da população geral (HuC/D) e nitrérgicos (imunorreativos à nNOS); e morfométrica dos neurônios imunorreativos à HuC/D ou nNOS; e das varicosidades imunorreativas à ChAT, VIP, CGRP ou SP. Amostras dos 3 segmentos intestinais foram preparadas e coradas em Hematoxilina e Eosina para análise histológica da morfologia básica. O segmento intestinal considerado mais afetado na análise morfométrica da população geral de neurônios, o duodeno, foi selecionado para a realização da análise proteômica, com o objetivo de oferecer o seu perfil proteico e determinar diferenças na expressão proteica em decorrência da exposição crônica ou aguda ao F. A análise da concentração de F no plasma sanguíneo foi realizada para a confirmação da exposição. Na análise quantitativa, o grupo de 50 ppm F, apresentou uma diminuição significativa na densidade da população geral de neurônios do jejuno e do íleo e na densidade dos neurônios imunorreativos à nNOS no duodeno e no jejuno. Quanto à análise morfométrica, a população geral e as subpopulações neuronais entéricas avaliadas apresentaram alterações morfológicas significativas, tanto após a exposição crônica quanto a aguda. Para a análise proteômica do duodeno, verificou-se que da associação de seus genes a um termo, e assim classificadas de acordo com diferentes processos biológicos. No caso do grupo da dose aguda, o processo biológico com a maior porcentagem de genes associados foi a geração de metabólitos precursores e energia (27% das proteínas); enquanto para os grupos de 10 e 50 ppm F foram o processo metabólico da piridina (41%) e a polimerização proteica (33%), respectivamente. / The gastrointestinal tract (GIT) is the main route of fluoride (F) exposure, and the most important site of its absorption. It is believed that F toxicity compromises the intestine physiology, due to the relevant gastrointestinal symptomatology reported in consequence to excessive exposure. The intestinal function is controlled by a complex neuronal net, which is interconnected and embedded in the wall of this organ, named Enteric Nervous System (ENS). Although the toxic effects of F on the Central Nervous system are described in the literature, there are no studies related to its toxicity on the ENS. Therefore, in this study performed in rats, the effects of chronic and acute F exposure were evaluated, on the general population of enteric neurons and on the subpopulations that express the main enteric neurotransmitters: Acetylcholine (Ach), Nitric Oxide (NO), Vasoactive Intestinal Peptide (VIP), Calcitonin gene related peptide (CGRP), and Substance P (SP). The animals were divided into 5 groups: 3 designed to the chronic exposure (0 ppm, 10 ppm ou 50 ppm de F in the drinking water) and 2 to the acute exposure (0 ou 25 mgF/Kg - gastric gavage). Three intestinal segments were collected (duodenum, jejunum, and ileum) and processed for the immunofluorescence techniques to detect HuC/D, ChAT, nNOS, VIP, CGRP and SP, on the myenteric plexus. Images were obtained for the quantitative analysis of the general population of neurons (HuC/D immunoreactive) and the nitrergic neurons (nNOS immunoreactive), for the morphometric analysis of the general population and nitrergic neurons and also for the immunoreactive varicosities to ChAT, VIP, CGRP or SP. Samples of the 3 intestinal segments were prepared and stained with hematoxylin and eosin for histological analysis of the basic morphology. Duodenum, the intestinal segment considered the most affected in the morphological analysis of the general population of neurons, was selected for the proteomic analysis, with the objective to offer the entire protein profile and to determine differences in the protein expression due to chronic or acute F exposure. Plasma F concentration was analyzed to confirm the exposure. In the quantitative analysis, the 50 ppm F group presented a significant decrease in the density of the general population of neurons in the jejunum and ileum, and in the density of the nitrergic neurons in the duodenum and jejunum. Regarding the morphometric analysis, the general population of neurons and all the neuronal subpopulations evaluated presented significant morphological alterations, for both exposures, chronic and acute. In the proteomic analysis of the duodenum, it was verified that both exposures caused alterations in the expression of intestinal proteins. These proteins identified with differential expression were distributed according the association of their genes to a specific term, and by this term classified in different biological process. In the group that received the acute dose the biological process with the highest percentage of associated genes was the generation of precursor metabolites and energy (27% of proteins), and for the 10 and 50 ppm F groups, they were pyridine nucleotide metabolic process (41%) and protein polymerization (33%), respectively.

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