An excised animal larynx model has been used in many studies to better understand the physiological and anatomical properties of the human larynx. One difference between an ex vivo model and an in vivo model is that ion loss occurs postmortem. To compensate for this in the excised model, researchers most commonly use a preservation method that includes completely submerging the specimen in isotonic saline (0.9% Na+Cl-) and then flash freezing it in liquid nitrogen. The flash freezing method allows researchers to maintain the integrity of the structures while also being able to gather specimens as they become available. Not enough research has been done to understand the effects of a preservation method on the outcomes of the study. Additionally, no common method has been established for preservation across studies to ensure that results are not being influenced by this variable. This prospective, mixed experimental design study includes three groups, a control group and two experimental groups. The control group consisted of 10 bench-mounted porcine larynges that were soaked in isotonic saline and flash frozen with liquid nitrogen. Prior to the experiment, the frozen larynges were thawed overnight before trials. The other two groups consisted of 10 bench-mounted porcine larynges each; these larynges were soaked in either isotonic saline or Ringer’s solution, a balanced fluid used in vivo to counteract dehydration. Larynges from these two groups were kept fresh and stored in a refrigerator overnight before trials. On the day of experimentation, each larynx was mounted on a bench top setup including three micropositioners to stabilize, adduct, and elongate the vocal folds. All the larynges were connected to a pseudolung via the trachea and humidified air was passed through to the vocal folds until phonation was achieved. Phonatory trials consisted of brief phonation followed by 5-minute desiccation intervals until phonation was no longer achieved. Phonation threshold flow (PTF), defined as the flow observed at the onset of phonation, was observed during each phonation trial; and flow values were compared within and between groups. Statistically significant differences were found between the Ringer’s group and the fresh saline group as well as between the Ringer’s group and the frozen saline group, indicating that PTF is influenced by the larynx preservation method.

Neste trabalho caracterizamos o nematoide Panagrolaimus sp. linhagem CEW2, originalmente isolado em Monte Negro (RO), Brasil e mantido em nosso laboratório em culturas monoxênicas contendo Escherichia coli. CEW2 se mostrou um nematoide extremófilo capaz de sobreviver ao dessecamento em 10% de umidade relativa por pelo menos 48h. Essa resistência é mais evidente em larvas de primeiro estádio (L1) do que em adultos ou larvas dauer. Quando pré-incubados por 48h em 98% de umidade relativa a sua resistência ao dessecamento aumenta e pode chegar a uma sobrevivência de 86,25% dos indivíduos no caso de L1. Os animais dessecados se tornam também resistentes ao congelamento. Os indivíduos pré-incubados em 98% de umidade relativa tornam-se resistentes ao congelamento. O retorno à atividade após secagem ou congelamento ocorre de maneira diferente dependendo da concentração de NaCl no meio, sugerindo que eles sejam, além de anidrobiontes e criobiontes, sejam também osmobiontes. Um outro aspecto da fisiologia de CEW2 que também começamos a caracterizar é a composição de polipeptídeos das vitelinas de seus ovos. SDS-PAGE das proteínas presente em ovos de CEW2 apresentam 6 bandas principais coradas por Coomassie Blue (com Mr que variam de 85 a 125 kDa), 3 a mais do que aquelas detectadas nos outros dois nematoides cujas vitelinas foram caracterizadas, Caenorhabditis elegans e Oscheius tipulae. Quando comparamos as vitelinas destas três espécies notamos que CEW2 não possui a vitelina de 180 kDa (YP170A e B de C. elegans e VT1 de O. tipulae). Essa análise comparativa das vitelinas de nematoides nos permitiu propor um esquema para a origem das três bandas extras detectadas em CEW2. Não foi possível purificar as vitelinas de CEW2 usando o mesmo protocolo que desenvolvemos para as vitelinas de O. tipulae e C. elegans. Isso se deve a uma atividade proteolítica presente nos homogeneizados de vermes que co-purifica com as vitelinas e leva a sua degradação durante a armazenagem. As atividades proteolíticas presentes nesses homogeneizados foram caracterizados por zimografia e foi possível purificar uma das bandas que cremos ser uma protease digestiva de CEW2 e a responsável pela degradação das vitelinas purificadas. / In this work we characterize some survival and reproductive strategies of the nematode Panagrolaimus sp., strain CEW2. CEW2 was originally isolated in Monte Negro (RO), Brazil. CEW2 is currently maintained in monoxenic cultures with E. coli in our laboratory and has proved to be an extremophile that survives desiccation at 10% relative humidity for at least 48 hours. First instar larvae (L1) are more resistant to desiccation than adults or dauer larvae. When pre-incubated for 48 h at 98% relative humidity their resistance to desiccation increases and can reach a survival rate of 86,25 % with L1individuals. The dried animals also become resistant to freezing. Worms that were pre-incubated at 98% relative humidity become resistant to freezing in water at -20 °C. The return to activity upon drying or freezing occurs differently depending on the NaCl concentration in the medium, suggesting that CEW2 is an osmobiont in addition to its anidrobiotic and criobiotic behavior. We also began to characterize another aspect of CEW2 physiology; the polypeptide composition of the vitellins in their eggs. SDS-PAGE of the proteins present in CEW2 eggs show 6 major Coomassie Blue stained bands (Mr ranging from 85-125 kDa), three more than those detected in the vitellins of Caenorhabditis elegans and Oscheius tipulae. When we compare the vitellins of these three species we notice that CEW2 lacks the yolk proteins of 180 kDa (YP170A and B present in C. elegans and VT1 in O. tipulae). The comparative analysis of nematode vitellins allowed us to propose a model for the origin of the three extra bands detected in CEW2. We propose that in CEW2 the polypeptides that are ortologous to the 180 kDa polypeptides of C. elegans and O. tipulae, suffer a proteolytic cleavage similar to that occurring with the precursor of YP115 and 88 in C. elegans. It was not possible to purify the vitellins of CEW2 using the same protocol developed for the vitellins of O. tipulae and C. elegans. This is due to a proteolytic activity present in homogenized worms which co-purifies with the vitellins and leads to their degradation during the procedure. Proteolytic activities present in these homogenates were characterized by zymography and it was possible to purify one of the bands that we believe to be a digestive protease from CEW2 responsible for the degradation of purified vitellins.

Rapid increases in air temperature in Arctic and subarctic regions are driving significant changes to surface water. These changes and their impacts are not well understood in sensitive high Arctic ecosystems. This thesis explores changes in surface water in the high Arctic pond complexes of western Banks Island, Northwest Territories, and examines the impacts of this change on vegetation communities. Landsat imagery (1985-2015) was used to detect trends in surface water, moisture, and vegetation productivity, aerial imagery change detection (1958 and 2014) quantified shifts in the size and distribution of waterbodies, and field sampling investigated factors contributing to observed changes. The impact of expanding lesser snow goose populations on observed changes in surface water was investigated using the aerial imagery change detection of 2409 waterbodies and an information theoretic model selection approach, while their impact on vegetation was assessed using data from field surveys. Our analyses show that the pond complexes of western Banks Island are drying, having lost 7.9% of the surface water that existed in 1985. This loss of surface water disproportionately occurred in smaller sized waterbodies, indicating that climate is the main driver. Model selection showed that intensive occupation of lesser snow geese was associated with more extensive drying and draining of waterbodies and suggests this intensive habitat use may reduce the resilience of pond complexes to climate warming. Evidence from field surveys suggests that snow goose foraging is also contributing to patches of declining vegetation productivity within drying wetland areas. Diminishing and degrading high Arctic pond complexes are likely to alter permafrost thaw and greenhouse gas emissions, as well as the habitat quality of these ecosystems. Additional studies focused the mechanisms of surface water loss, the direct impacts of wetland drying on vegetation, and the contributions of snow geese to these processes, are necessary to better understand the changes occurring on Banks Island. / Graduate

The present study was undertaken to evaluate the effects of stress on crystalline style characteristics in bivalves of Crassostrea angulata, Meretrix lusoria, and Perna viridis. Firstly, the crystalline style morphological characteristics in normal submerged condition was examined. The presence percentage of crystalline styles in C. angulata collected from different months ranged from 0 to 73%. While, it was 100% in M. lusoria and P. viridis. Secondly, the crystalline style morphological characteristics were investigated under stresses of starvation, hypoxia and desiccation. In C. angulata, the crystalline styles were absent after treated with each of the unfavorable conditions for 1 hour. In M. lusoria, under starvation and hypoxia conditions for 72 hours, the presence percentage of crystalline styles was significantly decreased. Even more, the presence percentages of crystalline styles in M. lusoria reduced to 22% when treated with desiccation for 2 hours. In P. viridis, the presence percentage of crystalline styles was 100% under starvation and hypoxia for 72 hours. In contrast, the mussels were totally dead under desiccation for 72 hours. By comparison, desiccation had greater influence on the three bivalves than starvation and hypoxia based on the standardized crystalline style wet weight (crystalline style wet weight/ shell length). Additionally, the presence percentage of crystalline styles in C. angulata was also influence by fed. In all, among the three examined species, oyster C. angulata is the most sensitive one to unfavorable conditions.

The objective of this study was to use an applied tracer to study lateral ground water flow paths in the top ~0.5 m of clay settling areas (CSA) in order to gain better understanding of hydrologic connectivity of CSAs to the surrounding hydrologic systems. The study site was located on the non-operational Mosaic Fort Mead Mine property in Fort Meade, Polk County, Florida. This lateral tracer test study is a follow up from a vertical tracer test study performed at the same site location in 2007. The CSA is generally composed of a well developed, clay rich, subangular-blocky surface layer ~0-1.0m, which exhibits abundant desiccation cracks plus other macropores underlain by a massive, saturated, clay-rich sublayer from ~1.0-2.5 m. A bromide tracer was applied into an injected trench. All 60L of the applied tracer flowed out of the down gradient face of the trench quickly, over an eleven minute period. The Bromide tracer was rapidly transported laterally and was detected as far as 16 m from the starting point just 24 hours after application, as well as in the inundated north pond adjacent to the study area. Bromide concentration distribution was not uniform over the study area during any time period, with an initial disorganized bromide pulse followed by secondary pulse concentrated on the north side of the sampling area. This spatial-temporal distribution of bromide indicates preferential flow through desiccation cracks or other macropores. Bromide concentrations in the north pond increased over time while pond stage fluctuated due to this shallow lateral macropore dominated flow in and out. Although it is most likely true that flow paths from the CSA to the adjacent hydrologic landscape during the wet season is dominated by rapid shallow lateral flow through macropores, specific flow paths, macropore length, diameter and distribution and fluxes still remain unquantified. Therefore, how the hydrology of CSAs affects the adjacent hydrologic landscape still remain unquantified.

The objective of this study was to use applied and naturally-occurring geochemical tracers to study the hydrology of clay settling areas (CSAs) and the hydrological connectivity between CSAs and surrounding hydrological landscapes. The study site is located on the Fort Meade Mine in Polk County, Florida. The surface of the CSA is covered in desiccation cracks which swell and shrink in response to wetting and drying. Bromide was used as an applied tracer to study hydrological processes in the upper part of the CSA. Bromide infiltrated rapidly and perched on an uncracked massive sublayer. Bromide concentrations attenuated in the upper part of the profile without being translated vertically down through the lower part of the profile suggesting that bromide was lost to lateral rather than to vertical downward transport. Infiltration and lateral flow were rapid suggesting that preferential flow through desiccation cracks and other macropores likely dominates flow in the upper part of the profile. Naturally-occurring dissolved constituents and stable isotopes of hydrogen and oxygen were used as naturally-occurring tracers to study the hydrological connectivity between the CSA and the surrounding hydrological landscape. The relative contributions of source waters were determined using a two-end, mass-balance mixing model with sodium as a conservative natural tracer. On average, water samples downgradient from the CSA were ~80% rainfall/ambient water and ~20% CSA water. Discharge from the CSA to the surrounding surface water bodies and surficial aquifer occurs laterally over, through, and/or under the berms and/or vertically through the thick uncracked massive sublayer. However, the precise flowpaths from the CSA to the surrounding hydrological landscape are unclear and the fluxes remain unquantified, so the effects of CSAs on the hydrology of the surrounding and underlying hydrological landscape also remain unquantified.

Discontinuous planes often develop in soils; examples include shear bands, desiccation cracks, polygonal faults, and hydraulic fractures. These discontinuities affect the mechanical behavior (stiffness and strength) and transport properties of sediments (fluid migration and diffusion). Contrary to discontinuities in solid materials, granular materials such as soils are already separated at the particle scale. Therefore, the fundamental understanding of the development of discontinuities in soils must recognize their inherent granular nature and effective-stress dependent behavior. This research focuses on particle-scale mechanisms involved in contraction-driven shear failure due to mineral dissolution, desiccation cracks, and hydraulic fractures. Complementary experimental, analytical and numerical methods are used to study three cases. Contraction-driven polygonal fault formation under the seabed. Shear failure planes are often found in sediments that formed under near horizontal burial conditions. Particle-scale volume contraction due to mineral dissolution causes a decrease in the state of stress from the insitu K0-condition to the active failure Ka stress field. Shear strain localization follows in sediment with post-peak strain softening response. Desiccation cracks in saturated fine soils. The formation of desiccation cracks in soils is often interpreted in terms of tensile strength, which contradicts the cohesionless, effective stress dependent frictional behavior of fine grained soils. Experimental results monitored using high resolution time lapse photography point to a proper effective stress-dependent mechanism centered on the invasion of the air-water interface membrane. Miscible and immiscible fluid-driven fracture formation. Hydraulic fracture in granular materials cause grain separation and the development of conduits for preferential fluid flow leading to fracture formation due to the forced invasion of either immiscible or miscible fluids. Capillary, seepage, and skeletal interparticle forces define particle scale mechanisms at the fracture tip. Numerical simulations confirm that the effective stress remains in compression everywhere throughout the granular medium in the three localization mechanisms.

Global concern about the environmental impacts of waste disposal and stringent implementation of environmental laws lead to numerous research on recycled materials. Increased awareness about the inherent engineering values of waste materials, lack of landfill sites and strong demand for construction materials have encouraged research on composite materials, which are either fully or partly made of recycled materials. This trend is particularly strong in transportation and geotechnical projects, where huge quantities of raw materials are normally consumed. Owing to the low mass-to-volume ratio, disposal of Expanded Polystyrene (EPS) is a major problem. In addition, EPS recycling methods are expensive, labour intensive and energy demanding. Hence, this thesis is focused on the development of a new soil composite made by mixing recycled EPS with expansive clays. Given the high cost of damage to various buildings, structures and pavements caused by the unpredictable ground movements associated with expansive soils, it has been considered prudent to try and develop a new method of soil modification using recycled EPS beads as a swell-shrink modifier and desiccation crack controller. The innovative application of recycled EPS as a soil modifier will minimise the quantity of waste EPS destined to the landfill considerably. An extensive experimental investigation has been carried out using laboratory reconstituted expansive soils - to represent varied plasticity indices - consisting of fine sand and sodium bentonite. Three soils notated as SB16, SB24 and SB32 representing 16%, 24% and 32% of bentonite contents respectively were tested with four EPS contents of 0.0%, 0.3%, 0.6% and 0.9%. The tests performed include compaction, free swell, swell pressure, shrinkage, desiccation, shear strength and hydraulic conductivity. All the tests have been performed at the respective maximum dry unit weight and optimum moisture content of the mixes. It has been observed that by mixing of recycled EPS beads with the reconstituted soil, a lightweight geomaterial is produced with improved engineering properties in terms of dry unit weight, swelling, shrinkage and desiccation. The EPS addition depends on the moulding moisture content of the soil. With increasing moisture content, additional EPS can be added. Also, there is a reduction in dry unit weight with the addition of EPS. Furthermore, the reduction of swell-shrink potential and desiccation cracking in soils, for example, is related to the partial replacement of soil particles as well as the elasticity of the EPS beads. There is a reduction in shear strength with the addition of EPS to soils. However, mixing of chemical stabilisers along with EPS can enhance the strength in addition to improved overall properties.

Le projet français de stockage des déchets nucléaires, géré par l’Andra, nécessite la récolte de données expérimentales sur la durabilité des bétons de référence. Dans cette étude, les sollicitations prises en compte sont les processus de désaturation/resaturation, la charge thermique et l’évolution mécanique. Ainsi l’analyse porte ainsi sur le couplage thermo-hydro-mécanique des bétons de référence de l’Andra, fabriqués à base de ciment CEM I et CEM V/A. L’état de saturation en eau et les retraits des matériaux, soumis à la dessiccation ou à la resaturation, sont conditionnés par les différentes conditions thermiques et hydriques imposées, ainsi que de leurs caractéristiques microstructurales. Par ailleurs, l’étude de l’évolution mécanique est approfondie à 20°C en fonction de l’état de saturation en eau. A court terme, différents essais ponctuels mettent en évidence un endommagement hydrique qui conditionne le comportement mécanique. A long terme, l’étude du fluage sous dessiccation révèle le couplage existant entre la durabilité, l’évolution mécanique des matériaux et la dessiccation / The French project of the storage of nuclear wastes, which is managed by the Andra, needs some experimental data on the durability of the concrete. Loadings which are taken into account are the desaturation/resaturation processes, the heat load and the mechanical evolution. Hence this study focuses on the coupling thermo-hydro-mechanical on concretes of the research program of Andra, made with CEM I and CEM V/A cement type. The water saturation degree and shrinkages of materials, which are subjected to desiccation or resaturation, are dependent on the imposed thermal and hydrous conditions and on their microstructural characteristics. Moreover the study of the mechanical evolution is gone further at 20°C in function of the water saturation degree. Different short-term tests highlight a hydrous damage, which determine the mechanical behaviour. The long-term study of desiccation creep shows the coupling between the durability, the mechanical evolution and the desiccation

Orientador: Tânia Marcia Costa / Resumo: A temperatura é uma das principais restrições ambientais à distribuição dos organismos, afetando a fisiologia e sobrevivência. Organismos que habitam a zona do entremarés estão constantemente expostos à variação da temperatura e, com as mudanças climáticas, esses organismos devem enfrentar condições diferentes, que incluem temperaturas mais elevadas, levando a maiores taxas de perda de água por evaporação e, consequentemente, redução do desempenho ou mortalidade. Neste estudo, testamos os efeitos da dessecação em duas espécies de caranguejos violinistas (Leptuca thayeri e Minuca rapax) que ocupam habitats distintos em relação à cobertura da vegetação e posição no entremarés e, portanto, podem responder de forma diferente ao estresse por dessecação e ao aumento da temperatura. Leptuca thayeri, que é restrita à zona intermediária do entremarés, é mais sensível à dessecação do que M. rapax, uma espécie generalista, com maiores taxas de dessecação e mortalidade quando expostas à dessecação por 120 minutos. Além disso, em comparação com M. rapax, L. thayeri possui uma carapaça mais permeável. Também avaliamos se o aumento de temperatura pode causar alterações fisiológicas na espécie mais restrita L. thayeri, tendo acesso a alimento e à água. Uma elevação de temperatura de 10 ° C e 20 ° C durante 72 h não causou mortalidade em L. thayeri nem mudanças na concentração de glicose e proteína na hemolinfa. No entanto, as temperaturas mais altas aumentaram os níveis de lactato desidrogen... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre