High levels of dust have been detected in the immediate vicinity of many stars, both young and old. A promising scenario to explain the presence of this short-lived dust is that these analogues to the zodiacal cloud (or exozodis) are refilled in situ through cometary activity and sublimation. As the reservoir of comets is not expected to be replenished, the presence of these exozodis in old systems has yet to be adequately explained. It was recently suggested that mean-motion resonances with exterior planets on moderately eccentric (e(p) greater than or similar to 0.1) orbits could scatter planetesimals on to cometary orbits with delays of the order of several 100 Myr. Theoretically, this mechanism is also expected to sustain continuous production of active comets once it has started, potentially over Gyr time-scales. We aim here to investigate the ability of this mechanism to generate scattering on to cometary orbits compatible with the production of an exozodi on long time-scales. We combine analytical predictions and complementary numerical N-body simulations to study its characteristics. We show, using order of magnitude estimates, that via this mechanism, low-mass discs comparable to the Kuiper belt could sustain comet scattering at rates compatible with the presence of the exozodis which are detected around Solar-type stars, and on Gyr time-scales. We also find that the levels of dust detected around Vega could be sustained via our proposed mechanism if an eccentric Jupiter-like planet were present exterior to the system's cold debris disc.

This thesis describes development of low cost indoor air quality (IAQ) monitoring system for research. It describes data collection of various parameters concentration present in indoor air and sends data back to host PC for further processing. Thesis gives detailed information about hardware and software implementation of IAQ monitoring system. Also discussed are building wireless ZigBee network, creating user friendly graphical user interface (GUI) and analysis of obtained results in comparison with professional benchmark system to check system reliability. Throughputs obtained are efficient enough to use system as a reliable IAQ monitor.

Roads alter the ecological landscape and affect the function and composition of nearby soil chemistry and plant communities in an area of impact termed the “edge-effect zone”. While the 6.3 million kilometers of roads in the US cover only about 1% of the land, the edge effect zone around these roads has been estimated to occupy nearly 20% of the total land area in the US (Forman 2000). The objective of this study was to examine the spatial extent of transported materials and impacts on forest soil and vegetative communities immediately surrounding roadways based on road types classified as “Highway,” “Two-Lane Paved,” and “Gravel.” This research was located within two watersheds in the state of Vermont, in areas where a substantial area of forest existed adjacent the roadway. Using GIS mapping, transects were constructed at right angles to the road, and samples were gathered at the Shoulder, Ditch, Backslope, 10m from the edge of the forest, and 50m from road center during the summer of May 2009 to August 2009. Soil samples were analyzed for a suite of nutrients and physical characteristics, as well as heavy metals. The forest composition and percent area coverage by species of herbaceous flora and woody shrubs were also recorded. The main effects from roads were dependent on the extent of clearing and topography modification required for a roadway. The spatial extent of these modifications was correlated positively with road use intensity. Highways have the greatest ecological impact and gravel roads the least impact. The cleared area defines how much sunlight is available to plant communities and the distance that road pollutants will travel. Some heavy metals (such as Pb, Cd, Ni and Zn) were correlated positively with road use intensity. Gravel roads have higher calcium content in nearby soil when compared to other road types. This is most likely due to mobilized dust from the road base. Proximity to all road types had neutralizing effects on the soil pH relative to the acidic native forest soil. Changes in microtopography next to the road have marked effects on the composition of plant communities through maintenance and direction of water flow. Ditch areas support wetland plants, and have greater soil moisture and sulfur content, while plant communities closer to the road are characteristic of drier upland zones. The area past the edge of the forest does not appear to be affected chemically or physically by any of the road types, possibly due to the dense vegetation that develops outside of the right-of-way. To reduce the ecological footprint of future road development, road corridors should be narrowed, traffic consolidated to mass transit systems such as busses or railroad, and buffer zones of vegetation next to the right-ofway should be encouraged to contain the spread of pollutants.

Thorium-230 and protactinium-231 have been widely used as proxies of oceanic processes in both modern and past marine environment. Their application as such proxies is, however, limited by sparse data from the modern ocean with which to characterize their distribution and behavior. This thesis aims to provide such data and to assess their uses as oceanic proxies for ocean circulation, sediment dissolution, and modern dust input. Twelve profiles of dissolved ²³⁰Th, ²³¹Pa and ²³²Th obtained on a meridional GEOTRACES section in the Southwest Atlantic confirm the expected transport and fractionation of ²³¹Pa from ²³⁰Th by deep ocean circulation out of the modern Atlantic. There is however neither a water mass dependence nor progressive change as water masses age, which challenges the use of sedimentary ²³¹Pa/²³⁰Th to assess past flow in the South Atlantic. Decreases of ²³⁰Th and ²³¹Pa observed in near-bottom water indicate enhanced sea-floor removal in regions where nepheloid layers are present. In a second study of sedimentary nuclides concentration, high-resolution ²³⁰Th_xs profiles from sediment in Southeast Atlantic exhibit increasing ²³⁰Thxs concentrations from core-top to a depth of ∼3 cm followed by relatively constant values at greater depth, suggestive of sediment dissolution in the upper sediment core. This observation suggests the use of ²³⁰Thxs to quantify sediment dissolution. Combined with sediment composition measurements, ²³⁰Th_xs also provides an assessment of which constituents are dissolving from the sediment. (²³¹Pa/²³⁰Th)_xs ratios do not appear to be affected by sediment dissolution. A third study, in the tropical Atlantic Ocean, combines water-column measurements of ²³⁰Th, ²³²Th with coeval aerosol measurements, and allows assessment and improvement of the use of ²³²Th to quantify dust input to the surface ocean. ²³²Th-derived dust flux increases from 0.43 g/m²/yr at low latitude in the South Atlantic to 10.70 g/m²/yr at higher latitude in the North Atlantic, and broadly agree with a model of dust input. The data presented in this thesis have expanded the dataset of ²³⁰Th, ²³²Th and ²³¹Pa in the Atlantic Ocean, and provide an insight into future uses of these nuclides as oceanic proxies.

Depuis plusieurs années déjà, nombre d’applications industrielles impliquant des nanomatériaux ont vu le jour mais les connaissances relatives aux dangers de ces nouveaux matériaux sont actuellement assez restreintes. Le développement de ces nouveaux produits ne pouvant se poursuivre sans une évaluation approfondie des risques pour l’environnement et au poste de travail, les dangers relatifs aux nanoparticules doivent être évalués. La toxicité potentielle de ces nouveaux matériaux est souvent mise en avant. Néanmoins, les risques d’incendie et d’explosion ne doivent pas être négligés. Centrées essentiellement sur les poudres de taille micrométrique, les données de la littérature ne permettent pas, en effet, à l’heure actuelle, d’évaluer la probabilité et la gravité d’une explosion de nanopoudres. Dans ce contexte, la sensibilité à l’inflammation et la sévérité d’explosion de nanomatériaux pulvérulents typiques ont été évaluées ainsi que la validité des appareillages et procédures standards, habituellement utilisés lors d’une telle démarche. Enfin, la méthodologie adoptée afin d’évaluer les risques d’inflammation et d’explosion d’une installation de production de nanopoudres et de sécuriser au mieux la santé des travailleurs exposés aux nanoparticules est illustrée aux travers de deux exemples. Cette démarche pourra servir de base à de futures analyses de risques concernant les produits nanostructurés, exercice qui va devenir indispensable et de plus en plus fréquent au vu du contexte économique et réglementaire / In the industrial and research fields, nanomaterials provides a growing interest and many industrial applications have already been developed in the last years. However, knowledge about the hazards related to these new materials is currently limited. As safe nanomaterial production cannot be permitted without a deeper evaluation of environmental and occupational hazards, hazards related to nanoparticles have to be evaluated. One often thinks about the potential toxicity of nanoparticles. However, dust fire and explosion should not be neglected when the dusts are combustible, which may often be the case. So far, literature studies concerning the evaluation of explosion and flammability risks of powders were essentially carried out on micron-sized materials and do not enable in fact to evaluate fire and explosion risk probabilities and gravities of nanopowders. The main goal of this work is to study explosion and ignition risks related to nanopowders. In particular, the evaluation of the explosion sensitivity and severity of typical nanomaterials has been studied as well as the validity of the existing analytical and methodological tools designed to evaluate dust ignition and explosion hazards. This work also deals with the methodology applied to a plant and to a laboratory in order to define the best safety barriers which were positioned to ensure the best occupational safety level to all workers and evaluate in a good way the ignition and explosion risks related to the use and production of fluffy nanomaterials. This work will certainly help risk engineers concerned about the handling and the production of combustible nanopowders.

Le Herschel Reference Survey (Boselli et al. 2010) est un programme clé à temps garanti conçu pour étudier les propriétés physiques du milieu interstellaire (MIS) de 323 galaxies proches, dotées de données multi-fréquences. Cet échantillon sélectionné en bande K et limité en volume est composé de galaxies couvrant tous les types de morphologies (des elliptiques aux galaxies spirales) et tous les types d'environnement (des galaxies de champs aux galaxies du centre de l'amas de la Vierge). Mon travail de thèse consiste à effectuer une photométrie submillimétrique précise de ces 323 galaxies, et de conduire une analyse statistique des propriétés du MIS de ces galaxies proches basée sur leur distribution spectrale d'énergie. Dans ce but, j'ai utilisé les modèles de Draine & Li (2007) que j'ai ajusté aux données. Les paramètres de sorties de ces modèles sont l'intensité du champ de radiation, l'abondance des PAH, la contribution des régions de photo-dissociation dans le chauffage de la poussière, et la masse de poussière. J'étudie les relations entre ces paramètres de sorties et les propriétés physiques telles que la masse stellaire, le taux de formation stellaire spécifique, la métallicité ou encore le type morphologique.Je vais présenter les études préliminaires liées à ces relations, entrainant une meilleur compréhension des processus en jeu dans le MIS, et procurer de nouveaux modèles infrarouges et submillimétriques paramétrés par les quantités physiques que je viens de citer. Ces modèles, calibrés sur les galaxies proches, seront déterminant pour l'étude des propriétés du MIS des galaxies à haut redshifts. / The Herschel Reference Survey (Boselli et al. 2010) is a guaranteed time key project aimed at studying the physical properties of the interstellar medium (ISM) of 323 nearby galaxies, covered by multi-wavelength data. This volume limited, K-band selected sample is composed of galaxies spanning the whole range of morphological types (from ellipticals to late-type spirals) and environments (from the field to the centre of the Virgo Cluster). My PhD work consists in performing a precise submillimeter photometry of every galaxies of the survey, and conducting a statistical study on the ISM properties of nearby galaxies based on the analysis of their spectral energy distributions. To achieve this goal I fit the data with the models of Draine & Li 2007. The output of Draine & Li (2007) models are the intensity of the interstellar radiation field, the PAH abundance, the contribution of photodissociation regions, the total mass of dust. I study the relations between these outputs and the physical properties such as the stellar mass, the specific star formation rate, the metallicity or the morphological type. I will present a preliminary analysis of these relations leading to a better understanding of the processes at play in the ISM and provide new infrared sets of templates from 8 to 500 microns parameterized by all the physical parameters just cited. These templates calibrated on nearby galaxies will be a benchmark for the study of the ISM properties of high redshift galaxies.

Master of Science / Department of Biological and Agricultural Engineering / Ronaldo G. Maghirang / Military installations in the United States may be large sources of fugitive dust emissions. Off-road vehicle training can contribute to air quality degradation resulting from increased wind erosion events as a result of soil disruption; however, limited information exists regarding the impacts of off-road vehicle maneuvering. This study was conducted to determine the effects of soil texture and intensity of training with off-road vehicles on fugitive dust emission potential due to wind erosion at military training installations. Multi-pass trafficking experiments, involving wheeled and tracked military vehicles (i.e., M1A1 Abrams tank, M925A1 water tanker and various HMMWV models), were conducted at three military training facilities with different climate and soil texture (i.e., Fort Riley, KS; Fort Benning, GA; and Yakima Training Center, WA). Dust emissions were measured on site using a Portable In-Situ Wind Erosion Laboratory (PI-SWERL) coupled with a DustTrak™ dust monitor. In addition, a top layer of soil was collected in trays and tested in a laboratory wind tunnel for dust emission potential. In wind tunnel testing, the amount of emitted dust was measured using glass-fiber filters through high-volume samplers. Also, the particle size distribution and concentration of the emitted dust were measured using a GRIMM aerosol spectrometer. Comparison of the PI-SWERL (with DustTrak™ dust monitor) and wind tunnel test (with GRIMM aerosol spectrometer) results showed significant difference and little correlation. Also, comparison of the filter and GRIMM aerosol spectrometer data showed significant difference but high correlation. The dust emission potential (as measured with the GRIMM spectrometer) was significantly influenced by soil texture, vehicle type and number of passes. For the light-wheeled vehicle, total dust emissions increased from 66 mg m-2 for undisturbed soil to 304 mg m-2 (357%) and 643 mg m-2 (868%) for 10 and 50 passes, respectively. For the tracked vehicle, an average increase in total dust emission of 569% was observed between undisturbed conditions and 1 pass, with no significant increase in emissions potential beyond 1 pass. For the heavy-wheeled vehicle, emissions increased from 75 mg m-2 for undisturbed soil to 1,652 mg m-2 (1,369%) and 4,023 mg m-2 (5,276%) for 10 and 20 passes, respectively. Soil texture also played an important role in dust emission potential. For all treatment effects, there was a 1,369% difference in emissions between silty clay loam soil and loamy sand soil.

Stream chemistry changes in response to snowmelt, but does not typically reflect thechemistry of the snowpack. This suggests that flow processes between snowmelt and streamsystem, such as interactions with the soil and bedrock, have an important control on waterchemistry and highlight the complex flow pathways from the snowpack to stream. To investigateflow processes in the upper Provo River watershed, northern Utah, we sampled three sites on theriver ~20 times per year during 2016 and 2017. The sites, from highest elevations to lowest wereSoapstone, Woodland, and Hailstone, corresponding to locations of active stream gauges. Toidentify possible water sources to the stream during snowmelt, water samples were taken forsnow, ephemeral streams, soil water, lake, and spring water. To investigate potential impacts ofmineralogy, samples were taken for dust, soil and bedrock. The upper Provo River showeddistinct temporal variation in filtered (<0.45 microns) stream water for 87Sr/86Sr, dissolvedorganic carbon (DOC), silica (Si), and Lead (Pb) during the snowmelt season. The watershed hasdistinct 87Sr/86Sr ratios for bedrock (0.7449)

This study utilizes major-, trace- and rare earth elements, as well as radiogenic isotopes (Rb-Sr, Sm-Nd, Pb), in bulk sediment, extracted glass shards, and discrete ash layers, at Ocean Drilling Program Site 1149 (Izu-Bonin Arc), Deep Sea Drilling Project Site 52 (Mariana Arc), and Integrated Ocean Drilling Program Sites C0011 and C0012 (Nankai Trough) in order to characterize and quantify the abundance of dispersed ash, rather than discrete ash layers, in sediments from the Northwest Pacific Ocean. Combination of the geochemical methods with multivariate statistical techniques, such as Q-mode Factor Analysis and multiple linear regressions, allows for differentiation of unique chemistries of the dispersed ash, and the terrigenous components. Therefore, we can document sources that change through time and space. At Site 1149 the bulk sediment is a mixture of two dust and two dispersed ash sources. The two dust sources show contrasting accumulation patterns changing over at a tectonically and climactically active time in Earth's past (~22 Ma) and yield a more complete history of Asian aridity than has been previously considered. We interpret the source of the ashes as basalt from the Izu-Bonin Front Arc (IBFA) and rhyolite from the Honshu Arc (HR). Comparison of the dispersed ash component to the discrete ash layers suggests that eruption frequency, rather than eruption size, drives the dispersed ash record. In contrast, at Site 52 Chinese Loess, IBFA, dispersed boninite from the Izu-Bonin arc, and a dispersed felsic ash of unknown origin are the sources. Interestingly, there are no boninite layers, yet boninite is dispersed within the sediment. Changes in the volcanic and eolian inputs through time indicate strong arc- and climate-related controls. The bulk sediment at Site C0011 is characterized by eolian dust, HR, and a dacite of unknown origin. Site C0012 is comprised of eolian dust, a dacite of unknown origin, as well as dacite and andesite from the Izu-Bonin Arc. Analysis of the total ash record at these two sites provides insight into subduction zone mass balance and water budgets as well as information about the changes in physical properties that result from the alteration of volcanic ash.

Abstract Background: The high prevalence of smoking on the mines contributes significantly to the public health burden due to exposure to crystalline silica dust and high HIV and TB prevalence rates. Progressive anti-tobacco legislation that informs workplace smoking policies is in existence but there are no formal smoking interventions to achieve the objectives of such policies and to facilitate health promotion. Health care workers, in particular have a vital role to play in this regard. Objectives: The objectives of this research study were to determine the knowledge, attitudes and practices of HCWs regarding prevention of smoking in gold mine workers and to use this information to propose a framework for a smoking intervention programme for the mines. Methods: This was a cross-sectional descriptive knowledge, attitudes and practice (KAP) study. Data were obtained from 69 HCWs using self-administered questionnaires, from 161 occupational lung disease (OLD) and 30 medical ward admission record reviews, and from 4 informal discussions. Results: While knowledge and attitudes about smoking was good overall and 84.1% of HCWs reported that they would routinely ask smoking status and document it, this was not done in practice. An overwhelming majority of HCWs are aware that smoking is harmful to one’s health (98.6%); is harmful to mine workers’ health (97.1%), and predisposes them to acquiring lung diseases (95.7%). Half (56.7%) of the nurses, but no doctors documented smoking history on admission and poor follow up of this advice (38.5%) is an area of concern. HCWs identified a need for support structures such as workplace and community programmes that include education, training and awareness campaigns. Conclusion: Overall, HCWS are responsive to workplace smoking interventions: they are knowledgeable, and show insight and have positive attitudes towards smoking interventions, but a more enabling environment is required to establish good workplace practices. To this end a “Proposed framework for smoking interventions on the mines, incorporating the HCW programme” has been developed and partially implemented. Awareness of this study and its preliminary findings has already demonstrated a paradigm shift in thinking about tobacco on the gold mines.