This study was designed to identify the knowledge and skills that welders employed in certain areas of manufacturing and fabrication in the Dallas-Fort Worth, Texas Metropolitan Area should possess.

<p dir="ltr">High exposure to manganese (Mn) through the inhalation of welding fumes has been shown to have a toxic effect to the human brain, leading to parkinsonian-like symptoms such as changes in mood, cognition, and motor function. Oxidative stress and GABAergic dysfunction, two proposed mechanisms implicated in Mn neurotoxicity, can be measured by edited MR spectroscopy (MRS). Previous animal studies have found depleted levels of glutathione, the brain’s antioxidant, and GABA in response to exposure to Mn. Past welder studies have shown altered GABA levels in highly exposed welders. However, GSH has not yet been measured in welders. Recent advances in edited MRS allow for the simultaneous measurement of GABA and GSH, however, one sequence does not ‘fit all’. Thus, there is a need to ensure accurate and reproducible measurements of these metabolites in the study of neurological disorders, such as Mn neurotoxicity.</p><p dir="ltr">The overall goal of this dissertation is to establish a reproducible edited MRS protocol and ensure accurate measurement of metabolites in the context of Mn neurotoxicity. This work has been accomplished in three steps. First, we developed an optimized and reproducible HERMES sequence that allows for the consistently reliable measurement of GABA and GSH at 3T. Second, we investigated whether toenail concentrations of manganese (Mn) and iron (Fe) serve as biomarkers for levels of GABA, GSH, and Glx in the brains of welders exposed to these metals. This aim explores the potential for toenails to be used as a risk assessment tool by evaluating correlations between toenail metal levels and brain metals and metabolites. Lastly, we examined whether excessive accumulation of metals in the brain has an impact on the relaxation times of metabolites. Due to its paramagnetic properties, brain accumulation of two major components of welding fumes, Mn and iron (Fe), may be measured noninvasively through increased magnetic resonance imaging (MRI) relaxation rates, R1 and R2*, respectively. This aim delves into the potential effects of metal exposure on the physical properties of brain metabolites, which could shed light on the accuracy of quantification.</p><p dir="ltr">Overall, the dissertation is a successful step towards establishing reproducible edited MRS acquisitions, and the accurate quantification in the application of Mn neurotoxicity. This work focused on developing methodologies and assessing physical properties for accurate GABA and GSH measurements and investigating risk-assessment methods for metal-induced neurotoxicity.</p>

L’étude des effets respiratoires d’aérosols d’oxydes métalliques par inhalation chez la souris est motivée par les observations chez les patients soudeurs. En effet, les soudeurs développent des pathologies cardio-respiratoires qui pourraient être directement ou indirectement liées à l’exposition aux fumées de soudage. Ces fumées de soudage sont composées de différentes espèces chimiques, de poussières mais aussi de nanoparticules (NP). En effet, on retrouve des NP jusqu’à 80 % en nombre et 11% en masse dans les fumées de soudage. Dans le but d’évaluer le rôle de la composante nanoparticulaire des fumées de soudage, mon sujet de thèse est centré sur l’étude des effets respiratoires d’expositions répétées aux aérosols de NP d’oxydes de fer et de manganèse par inhalation chez la souris Dans le précédent rapport, nous avions présenté la technique de génération des aérosols d’oxydes de NP / Traduction de Reverso en Anglais The study of the respiratory effects of sprays of metal oxides by inhalation to the mouse is motivated by the observations at the patients welders. Indeed, the welders develop cardio-respiratory pathologies which could be directly or indirectly bound to the exhibition in smokes of soldering. These smokes of soldering are consisted of various chemical species, dusts but also nanoparticles (NP). Indeed, we find NP until 80 % in number and mass 11 % in smokes of soldering. With the aim of estimating the role of the component nanoparticulaire smokes of soldering, my thesis subject is centered on the study of the respiratory effects of exhibitions repeated to the sprays of NP of iron oxide and manganese by inhalation to the mouse

This master thesis report presents a 20 weeks long project within Industrial design engineering at Luleå University of Technology, performed at Volvo Group Trucks Operations in Umeå. Since the company from a previous study knew that the operators on segment two work in unfavorable work postures, a further investigation of the operators’ work environment was needed. Therefore, the subject of investigation in this project became the physical workload and more specifically, the factors related to the appearance of work related musculoskeletal disorders (MSDs). Segment two is positioned at the end of Volvos’ production line called finishline where the work is primarily done manual by two shift teams with approximately 14 operators in each one. The project objective was to map the current situation for the manual welding operators at segment two and identify potential ergonomic risks within their everyday work. The focus was placed on finding improvements that could decrease the operators’ risk for developing MSDs during work. The project aim was to develop improvements that direct, and over a longer time span, could ease and improve the operators work situation. By observing, filming, interviewing and hand out questionnaires, the current state for the operators could be mapped. Three interviews were held, 22 questionnaires were answered and almost 50 film sequences were made. The work on segment two are station based where the operators are allocated a specific time for each operation within the station. Usually, the operators rotate after ten truck cabs and then move to the next station. The work consists of screwing, welding, grinding, drilling and controlling. The situation analysis was done by investigating the questionnaire responses further, explore the body postural MSD risks with help of RULA and REBA and using the software AviX to let the operators self-estimate the strain in different muscle groups during work. According to the questionnaires, the operators are highly or partly strained physical and psychological where the experienced psychological strain variates more than the physical strain. Furthermore, most of the operators experienced the occurring work acceleration as positive and the manager and coworker relationship as good. Also, ten operators expressed that they had experienced pain in their body the last 12 months caused by their work and over 70 % of the operators wanted to have a greater opportunity to affect the number of work tasks. By relating this to the findings in the study made at Volvo in 2011, where the investigators identified knee-standing work together with some critical work postures that caused the operators an unfavorable strain in mainly the neck, the back and the arms, I assume that the work on segment two today is performed during similar circumstances and in a similar way. The concept development started with an ideation session together with the operators. Here, the analysis findings were discussed, and my own ideas and improvement suggestions were presented. From these discussions, three tests were arranged including a step construction to facilitate when entering and leaving the truck cab, new knee pads and a stretch program, developed by Volvos’ ergonomist. The findings from the two first tests showed how different the operators found the concepts where some operators appreciated both the step construction and the knee pads, and some didn’t. The stretch test on the other hand, were appreciated by all operators where over 50 % felt an improvement in their body. Also, an educational approach including an additional introduction, updated work instructions and a continuous dialogue about work environmental risks during the group meetings were proposed. The tests resulted in a concept development, a concept evaluation with help of previous established specifications of requirements and the ergonomist, together with an implementation strategy. The strategy proposes an implementation of stretch during the workday within the following months, a further investigation of the knee pads and the step construction, and an implementation of the complete educational approach within 5-10 years. Also, based on the results of this thesis, Volvo are recommended to establish guidelines for how to measure work environmental factors linked to physical and psychosocial work environment. Further, the company are recommended to prioritize their employees’ health, well-being and work environment by working systematically in a close cooperation with the workforce to not risk costs in terms of dissatisfaction, sick leaves and poor reputation.

<p dir="ltr">Manganese (Mn) is an essential trace element for humans that functions primarily as a coenzyme in several biological processes such as nerve and brain development, energy metabolism, bone growth and development, as well as cognitive functioning. However, overexposure to environmental Mn via occupational settings or contaminated drinking water can lead to toxic effects on the central nervous systems and cause a Parkinsonian disorder that features symptoms such as fine motor control deficits, dystonia rigidity, speech and mood disturbances, and cognitive deficits summarized under the term “manganism”. Over time, Mn exposure has shifted from acute, high-level instances leading to manganism, to low-level chronic exposure. Considering that Mn exposure is significantly lower than in the past, it is unlikely to expect manganism from chronic Mn exposure under current working conditions. Therefore, there is a need to develop sensitive methods to aid in updating the clinical diagnostic standards for manganism and Mn neurotoxicity as chronic exposure to Mn leads to more subtle symptoms.</p><p><br></p><p dir="ltr">Historically, magnetic resonance imaging (MRI) has been used as a non-invasive tool for detecting excess brain Mn accumulation. Specifically, T1-weighted images show bilateral hyperintensities of the globus pallidus (GP) due to the paramagnetic properties of Mn which increases the MR relaxation rate R1. Although the GP is considered the hallmark of excess brain Mn, this brain area is not necessarily associated with symptoms, exposure, or neuropsychological outcomes. Thus, the focus should not be on the GP only but on the entire brain. With recent advances in quantitative MRI (qMRI), whole brain mapping techniques allow for the direct measurement of relaxation rate changes due to Mn accumulation. The work in this dissertation uses such quantitative techniques and network science to establish novel computational in vivo imaging methods to a) visualize and quantify excess Mn deposition at the group and individual level, and b) characterize the toxicokinetics of excess brain Mn accumulation and the role of different brain regions in the development of neurotoxicity effects.</p><p><br></p><p dir="ltr">First, we developed a novel method for depicting excess Mn accumulation at the group level using high-resolution R1 relaxation maps to identify regional differences using voxel-based quantification (VBQ) and statistical parametric mapping. Second, we departed from a group analysis and developed subject-specific maps of excess brain Mn to gain a better understanding of the relationship between the spatial distribution of Mn and exposure settings. Third, we developed a novel method that combines network science with MRI relaxometry to characterize the storage and propagation of Mn and Fe in the human brain and the role of different brain regions in the development of neurotoxic effects. Lastly, we explore the application of ultra-short echo (UTE) imaging to map Fe content in the brain and compare it against R2* and quantitative susceptibility mapping (QSM).</p><p><br></p><p dir="ltr">Overall, this dissertation is a successful step towards establishing sensitive neuroimaging screening methods to study the effects of occupational Mn exposure. The individual Mn maps offer great potential for evaluating personal risk assessment for Mn neurotoxicity and allow monitoring of temporal changes in an individual, offering valuable information about the toxicokinetics of Mn. The integration of network science provides a holistic analysis to identify subtle changes in the brain’s mediation mechanisms of excess metal depositions and their associations with health outcomes.</p>

Thesis (MPA)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The Democratic South African government inaugurated in 1994 identified the need for intermediate skills that are required to contribute to the growth of the economy and to reduce the high unemployment rate. Further Education and Training Colleges (FETC) were established after 1994 by merging the former 152 technical colleges into 50 FETCs. The function of these FETCs was to offer intermediate skills to the youth, women, and employed and unemployed South Africans. The South African government introduced a number of strategies, Acts and policies to support the colleges and to implement demand-driven intermediate skills programmes which would close the skills gap and improve the growth of the economy. These policies seek to ensure that skills offered at colleges are aligned to the needs of industry and to make sure that the college programmes will be in demand in the work place. The study presented is aimed at investigating this alignment by evaluating how apprentices in the final stage of their vocational training perform and meet the demands at their work places. A number of strategies used by different countries to support and develop their education systems are discussed. The discussion is directed at considering how vocational education ensures a positive contribution to skills development and what its impact is on the growth of the economy. This study provides a comprehensive policy and legislative framework which governs and supports the higher education institutions and the FETCs. The study was designed to determine whether welding apprentices from the College are, according to the work place staff and management and stakeholder bodies, appropriately equipped with vocational skills and knowledge to execute their duties at the work place. The evaluation and analysis of the data extracted from the responses of the interviews and questionnaires are presented and discussed. The results enabled the researcher to conclude that the evaluation of apprentice performance at the work place provides significant insight into the question of how vocational training and knowledge at the WCFETC meet the demands at the work place. Conclusions are drawn and recommendations are made. / AFRIKAANSE OPSOMMING: Die demokratiese Suid-Afrikaanse Regering, wat in 1994 ingehuldig is, het die behoefte aan intermediêre vaardighede om die groei van die ekonomie en die van die hoë werkloosheidssyfer te verlig, geïdentifiseer. Verdere Onderwys en Opleiding Kolleges (VOOKS) is na 1994 totstand gebring deur die samesmelting van 152 voormalige Tegniese kolleges tot 50 VOOKS. Die funksie van die Verdere Onderwys en Opleiding Kolleges was om intermediêre vaardighede aan die jeug, vrouens en Suid-Afrikaners in diens of werkloos, te verskaf. Die Suid-Afrikaanse Regering het ´n aantal strategieë, wette en beleidsrigtings aangeneem om die kolleges te ondersteun en om die aanvraag-gedrewe intermediêre vaardigheidsprogramme te implementeer wat dan die vaardigheidsgaping sou vernou en die groei van die ekonomie sou bevorder. Hierdie beleidsrigting beoog om te verseker dat vaardighede wat by die Kolleges aangebied word, belyn is met die industrie as ook om te verseker dat die kollege programme benodig word in die werksplek. Die studie is gemik daarop om hierdie belyning te ondersoek en te evalueer hoe vakleerlinge in die laaste stadium van hulle ambagsopleiding vaar, en voldoen aan die eise van die werksplek. ´n Aantal strategieë wat deur verskillende lande gebruik word, om hulle eie opvoedingsstelsels te ontwikkel, word bespreek. Die bespreking verwys na hoe ambagsopvoeding ´n toevoeging tot vaardigheidsontwikkeling kan verseker en wat die impak daarvan op die groei van die ekonomie het. ´n Alomvattende beleid en ´n wetsraamwerk, wat Hoër OpvoedingsInstansies en die Verdere Onderwys en Opleiding Kolleges beheer en ondersteun, word verskaf. Die studie is ontwerp om te bepaal of die sweis vakleerlinge van die kollege, volgens die werksplek personeel en -bestuur en belanghebbende liggame, toepaslik toegerus en bevoeg is met ambagsvaardighede en kennis om die pligte van die werksplek uit te voer. Die evaluering en analise van die data, afgelei van die terugvoering van die onderhoude en vraelyste, word weergegee en voledig bespreek. Die resultate stel die navorser in staat om tot die gevolgtrekking te kom dat die evaluering van vakleerling-werksverrigting by die werksplek merkbare insig tot die vraag hoe ambagsopleiding en kennis by die Weskus VOOK aan die eise van die werksplek voldoen. Gevolgtrekkings en aanbevelings word aangebied.