No description available.

Effective monitoring and modelling of the marine environment is of importance to both the general public and the scientific community, but relies on the ability to obtain accurate measurements of suspended particle characteristics. Many instruments for measuring particles rely on optical and acoustic scattering from the particles and use this information to infer a particle size and concentration. However, assumptions such as spherical particles of a known composition are widely used, both in measurement technology and in numerical modelling. Various imaging techniques have shown great variability in the shape, size and composition of marine particles when measured within their natural environment. Subsequently, there is substantial uncertainty in the response of light scattering instruments to this diverse range of particles. In this study, a holographic camera was modified to simultaneously record in-focus images of marine particles with their forward angle scattering characteristics. This was achieved by combining both laser scattering and transmissometry with digital holography. The results from this system were compared with theoretical models of scattering from spherical particles within the intended size range of both instruments (15-500microns), with particle size information from both techniques agreeing well during these idealised conditions. The combined holographic and light scattering system was then used to investigate the response of the LISST-100 (Sequoia Scientific Inc.) to spherical particles with diameters extending beyond that intended by the instrument 250microns for type-B and 500microns for type-C derivatives), but that have been observed in-situ with imaging methods. This revealed an aliasing of single large particles into multiple smaller particles during the inversion of LISST-100 scattering into a particle size distribution. For spheres greater than the type-C instrument range, the inversion of scattering produces particle volume distributions that peak at varying sizes between 250-400microns. This key finding highlights the need for care to be taken when interpreting particle size distributions from the LISST-100 when there is potential for particles outside of its range limit. Natural particles, extracted from coastal waters, were then recorded by the combined laboratory system. These complex particles produced highly variable scattering properties which were contaminated by asymmetrical features within the azimuthal plane. This observation of strong azimuthal asymmetry is of concern for both measurements and models of optical properties that assume a symmetrical scattering function for natural particle populations. The azimuthal asymmetry in scattering contributed to additional variability in the response of the instrument in comparison to the holographic camera, which was also subjected to apparent particle break-up via segmentation during image processing. A discussion of holographic imaging and laser diffraction for characterising particles in-situ forms the final part of this thesis, which utilises data from a magnified holographic system that covers the same size range of the LISST-100. This final analysis demonstrated the need for future technology to accurately measure size distributions over a much larger range of sizes than is currently possible (e.g. <2microns to 1000microns). In summary, three key factors were identified to cause an increase in the apparent number of small particles reported by the LISST-100: 1) contamination from scattering of particles larger than the intended size range of the instrument; 2) a decrease in refractive index (particle composition); 3) additional scattering from small sub-components of particle geometry. The standard holographic camera systems are capable of accurately obtaining particle size and concentration measurements that are comparable to other techniques such as the LISST-100. However, in situations where background illumination is poor, errors in the image processing routines can cause an apparent particle break-up due to incorrect binarisation. Despite this, the holographic method provides a unique and powerful mechanism that enables images of particles to be analysed within the context of their in-situ environment.

Particle size distribution (PSD) of gypseous soils is important in the soil science community. When gypsum constitutes a major portion of the soil, its removal prior to PSD analysis distorts the results and may lead to textures that do not relate to conditions in the field. In order to understand the true characterization of the soil and the gypsum particles, the entire soil sample should be analyzed. Four different approaches to the BaCl2 method presented in the literature (Hesse, 1976, Matar and Douleimy, 1978, Viellefon, 1979) were used to evaluate the use of BaCl2 solution to reduce the solubility of gypsum by forming a protective coating of BaSO4 around gypsum particles. Results showed that the BaCl2 method was unsatisfactory, as dispersion of clays was not sufficient to allow particle size analysis using the pipette method. A procedure using a laser diffraction particle size analyzer (LPSA) was also evaluated. As gypsum is insoluble in methanol, methanol was selected as a possible solution, but it caused flocculation of clays and could not be used to analyze samples containing silicate clays. Gypsum saturated water containing Na hexametaphosphate was evaluated as a solution. First, 20 non-gypseous samples were analyzed on a sand-free basis using saturated gypsum water with Na hexametaphosphate. Results were used to establish a relationship comparing LPSA results and pipette results. An equation y = 1.37x + 2.03 was established relating LPSA clay percent by volume (x) to the pipette clay percent by weight (y). The equation had a R2 value of 0.84 and was significant at the 1% level. From this equation a comparison of 21 gypseous samples was made, between clay percentages of the pipette method and the LPSA method. Results indicate that LPSA can be used to give a satisfactory particle size distribution of gypseous soils when coupled with sand analysis by sieving.

Particle size distribution (PSD) of gypseous soils is important in the soil science community. When gypsum constitutes a major portion of the soil, its removal prior to PSD analysis distorts the results and may lead to textures that do not relate to conditions in the field. In order to understand the true characterization of the soil and the gypsum particles, the entire soil sample should be analyzed. Four different approaches to the BaCl2 method presented in the literature (Hesse, 1976, Matar and Douleimy, 1978, Viellefon, 1979) were used to evaluate the use of BaCl2 solution to reduce the solubility of gypsum by forming a protective coating of BaSO4 around gypsum particles. Results showed that the BaCl2 method was unsatisfactory, as dispersion of clays was not sufficient to allow particle size analysis using the pipette method. A procedure using a laser diffraction particle size analyzer (LPSA) was also evaluated. As gypsum is insoluble in methanol, methanol was selected as a possible solution, but it caused flocculation of clays and could not be used to analyze samples containing silicate clays. Gypsum saturated water containing Na hexametaphosphate was evaluated as a solution. First, 20 non-gypseous samples were analyzed on a sand-free basis using saturated gypsum water with Na hexametaphosphate. Results were used to establish a relationship comparing LPSA results and pipette results. An equation y = 1.37x + 2.03 was established relating LPSA clay percent by volume (x) to the pipette clay percent by weight (y). The equation had a R2 value of 0.84 and was significant at the 1% level. From this equation a comparison of 21 gypseous samples was made, between clay percentages of the pipette method and the LPSA method. Results indicate that LPSA can be used to give a satisfactory particle size distribution of gypseous soils when coupled with sand analysis by sieving.

No description available.

Thèse doctorat : Optique et Laser : Strasbourg 1 : 2007. / Titre provenant de l'écran-titre. Bibliogr. 5 p.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The tillage system, widely used in Rio Grande do Sul, provides improvements in plant soil environment. However, due to the traffic of machines in areas not have upturn the formation of subsurface layers with higher compaction states. To adapt the soil to crops is necessary practices of tillage. The implements used for these practices beyond breaking compacted layers end up breaking the soil aggregates, disrupting it. In lime and gypsum is added to the soil ions that can influence the approximation of soil particles and consequently the aggregation of this. The objective of this study is to evaluate the effects of liming and gypsum application practices in the area of tillage subjected to soil management operations, the physical properties. In June 2009 the establishment of the experiment was conducted, in Oxisol cultivated over ten years under no-tillage, was adopted split-split plot design, with different tillage operations of the allocated land in main plots (tillage + plowing, tillage + scarification and continuous tillage), lime rates in subplots (0, 2, 4 e 6 Mg ha-1) and rates of gypsum in subsubplots (0, 2, 4 e 6 Mg ha-1). Three years after the implementation of the trial trenches soil samples were collected and opened. Samples were collected at different layers (0 a 5, 5 a 10, 10 a 15, 15 a 20, 20 a 30 e 30 a 40 cm) in order to diagnose the effect of product in the soil profile. Soil core soil samples were collected to determine soil density, microporosity and macroporosity and total porosity of soil penetration resistance. Blocks with preserved structure were collected and manually defragmented in aggregate. With the aid of sieves were separated aggregates with diameters between 8 a 4,75 mm for analysis of aggregate stability in water and aggregates with diameters between 1 e 2 mm for laser diffraction analysis of microaggregates. Liming and gypsum altered the physical properties, without a decrease in macroporosity and total porosity, increased resistance to penetration, which decreased the area under the scarification. The aggregation of the soil was influenced by management practices and lime and gypsum. Smaller fractions of aggregates are more sensitive in diagnosing changes in soil structure, broken down by the Stability Aggregate Index for laser diffraction. / O sistema de plantio direto, amplamente utilizado no Rio Grande do Sul, proporciona melhorias no ambiente solo planta. Contudo, devido ao tráfego de máquinas em áreas não revolvidas, têm-se a formação de camadas subsuperficiais com maiores estados de compactação. Os implementos utilizados para romper as camadas compactadas acabam rompendo os agregados do solo, desestruturando-o. Na calagem e gessagem são introduzidos ao solo íons que podem influenciar na aproximação de suas partículas e, consequentemente, na agregação deste. Assim, o objetivo deste trabalho é avaliar os efeitos das práticas de calagem e gessagem nas propriedades físicas do solo em área de plantio direto submetida a diferentes operações de manejo de solo. Em junho de 2009, foi realizado a implantação do experimento em Latossolo Vermelho cultivado há mais de dez anos sob sistema de plantio direto. Foi adotado delineamento de parcelas subsubdivididas, com diferentes operações de preparo do solo alocadas nas parcelas principais (plantio direto + aração; plantio direto + escarificação; plantio direto contínuo), doses de calcário em subparcelas (0, 2, 4 e 6 Mg ha-1) e doses de gesso em subsubparcelas (0, 2, 4 e 6 Mg ha-1). Três anos após a implantação do experimento foram abertas trincheiras e coletadas amostras de solo em diferentes camadas (0 a 5, 5 a 10, 10 a 15, 15 a 20, 20 a 30 e 30 a 40 cm), a fim de diagnosticar o efeito dos tratamentos no perfil do solo. Com anéis volumétricos, foram coletadas amostras de solo para determinação da densidade do solo, microporosidade, macroporosidade e porosidade total do solo e resistência à penetração. Blocos com estrutura preservada foram coletados e desfragmentados manualmente em agregados. Com auxílio de peneiras, foram separados agregados com diâmetro entre 8 a 4,75 mm para análise de estabilidade de agregados em água e com diâmetro entre 1 e 2 mm para análise de difração a laser de microagregados. A calagem e a gessagem alteraram as propriedades físicas, ocorrendo a diminuição da macroporosidade e porosidade total, aumento da resistência à penetração e, consequentemente, a diminuição na área submetida à escarificação. A agregação do solo foi influenciada pelas práticas de manejo e doses de calcário e gesso. As menores frações de agregados são mais sensíveis em diagnosticar alterações na estrutura do solo, discriminado pelo Índice de Estabilidade de Agregados para a difração a laser.

Master of Science / Department of Biological & Agricultural Engineering / Ronaldo G. Maghirang / Large cattle feedlots emit considerable amounts of particulate matter (PM), including TSP (total suspended particulates), PM[subscript]10 (PM with equivalent aerodynamic diameter of 10 μm or less), and PM[subscript]2.5 (PM with equivalent aerodynamic diameter of 2.5 μm or less). Particulate emissions result from pen surface disturbance by cattle hoof action, vehicle traffic on unpaved roads and alleyways, and wind erosion. Research is needed to determine concentrations of various size fractions, size distribution, and emission rates from various sources in feedlots. This research was conducted to measure particle size distribution using laser diffraction method and estimate emissions from unpaved roads and wind erosion. Particle size distribution and concentrations of PM[subscript]10 and PM[subscript]2.5 at a commercial cattle feedlot in Kansas (Feedlot 1) were measured over a 2-yr period. The feedlot had a capacity of 30,000 head and total pen area of 50 ha and was equipped with a sprinkler system for dust control. Collocated low-volume samplers for TSP, PM[subscript]10, and PM[subscript]2.5 were used to measure concentrations of TSP, PM[subscript]10, and PM[subscript]2.5 at the upwind and downwind edges of the feedlot. Dust samples that were collected by TSP samplers were analyzed with a laser diffraction analyzer to determine particle size distribution. Particle size distribution at the downwind edge of the feedlot was also measured with micro-orifice uniform deposit impactor (MOUDI). The laser diffraction method and MOUDI did not differ significantly in mean geometric mean diameter (13.7 vs. 13.0 μm) but differed in mean geometric standard deviation (2.9 vs. 2.3). From laser diffraction and TSP data, PM[subscript]10 and PM[subscript]2.5 concentrations were also calculated and were not significantly different from those measured by low-volume PM[subscript]10 and PM[subscript]2.5 samplers (122 vs. 131 μg/m[superscript]3 for PM[subscript]10; 26 vs. 35 μg/m[superscript]3 for PM[subscript]2.5). Both PM[subscript]10 and PM[subscript]2.5 fractions decreased as pen surface moisture contents increased, while the PM[subscript]2.5/PM[subscript]10 ratio did not change much with pen surface moisture content. Published emission models were used to estimate PM[subscript]10 emissions from unpaved roads and wind erosion at Feedlot 1 and another nearby feedlot (Feedlot 2). Feedlot 2 had a capacity of 30,000 head, total pen surface area of 59 ha, and used water trucks for dust control. Estimated PM[subscript]10 emissions from unpaved roads and wind erosion were less than 20% of total PM[subscript]10 emissions obtained from inverse dispersion modeling. Further research is needed to establish the applicability of published emission estimation models for cattle feedlots.

Sedimentation (erosion, transport, and deposition) is a primary and growing environmental, engineering, and agricultural issue around the world. However, collection of the data needed to develop solutions to sedimentation issues has declined by about three-fourths since 1983. Suspended-sediment surrogates have the potential to obtain sediment data using methods that are more accurate, of higher spatial and temporal resolution, and with less manually intensive, costly, and hazardous methods. The improved quality of sediment data from high-resolution surrogates may inform improved understanding and solutions to environmental, engineering, and agricultural sedimentation problems. The field experiments for this research includ physical samples of suspended sediment collected concurrently with surrogate metrics from instruments including 1.2, 1.5, and 3.0 megahertz frequency acoustic doppler current profilers, a nephelometric turbidity sensor, and a laser-diffraction particle size analyzer. This comprehensive data set was collected over five storms in 2009 and 2010 at Yellow River near Atlanta, Georgia. This research project has proposed, developed, and tested a new method for evaluation of sediment size from theoretical acoustic attenuation; evaluated and further developed recently introduced empirical methods for estimating acoustic attenuation by sediment; found and quantified data mischaracterization issues for laser-diffraction metrics; defined deterministic causes for observed hysteresis and variance in suspended sediment to surrogate relations; compared the accuracy of sediment concentration models and loads for each tested surrogate; and compared sediment surrogate technologies on the basis of reliability and operational considerations.

Tendon transfer surgery is used to improve the hand function of patients with nerve injuries, spinal cord lesions, cerebral palsy (CP), stroke, or muscle injuries. The tendon of a muscle, usually with function opposite that of the lost muscle function, is transferred to the tendon of the deficient muscle. The aim is to balance the wrist and fingers to achieve better hand function. The position, function, and length at which the donor muscle is sutured is essential for the outcome for the procedure. In these studies the significance of the transferred muscle’s morphology, length and apillarization was investigated using both animal and human models. Immunohistochemical, biochemical, and laser diffraction techniques were used to examine muscle structure. In animal studies (rabbit), the effects of immobilization and of tendon transfers at different muscle lengths were analyzed. Immobilization of highly stretched muscles resulted in fibrosis and aberrant regeneration. A greater pull on the tendon while suturing a tendon transfer resulted in larger sarcomere lengths as measured in vivo. On examination of the number of sarcomeres per muscle fiber and the sarcomere lengths after 3 weeks of immobilization and healing time, we found a cut-off point up to which the sarcomerogenesis was optimal. Transfer at too long sarcomere lengths inhibited adaptation of the muscle to its new length, probably resulting in diminished function. In human studies we defined the sarcomere lengths of a normal human flexor carpi ulnaris muscle through the range of motion, and then again after a routinely performed tendon transfer to the finger extensor. A calculated model illustrated that after a transfer the largest force was predicted to occur with the wrist in extension. Morphological studies of spastic biceps brachii muscle showed, compared with control muscle, smaller fiber areas and higher variability in fiber size. Similar changes were also found in the more spastic wrist flexors comparing with wrist extensors in children with CP. In flexors, more type 2B fibers were found. These observations could all be due to the decreased use in the spastic limb, but might also represent a specific effect of the spasticity. In children and adults with spasticity very small fibers containing developmental myosin were present in all specimens, while none were found in controls. These fibers probably represent newly formed fibers originating from activated satellite cells. Impaired supraspinal control of active motion as well as of spinal reflexes, both typical of upper motor syndrome, could result in minor eccentric injuries of the muscle, causing activation of satellite cells. Spastic biceps muscles had fewer capillaries per cross-sectional area compared to age-matched controls, and also a smaller number of capillaries around each fiber. Nevertheless, the number of capillaries related to the specific fiber area was normal, and hence the spastic fibers are sufficiently supplied with capillaries. This study shows that the length of the muscle during tendon transfer is crucial for optimization of force output. Laser diffraction can be used for accurate measurement of sarcomere length during tendon transfer surgery. Wrist flexor muscles have more morphological alterations typical of spasticity compared to extensors.