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1
Román, Cascón Carlos. « Variability of turbulent fluxes (momentum, heat andCO2) during Upwelling conditions. A case study ». Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303975.
Texte intégralRésumé :
Measurements of turbulent fluxes (momentum, sensible heat, latent heat and CO2) at two different heights were studied from data of a tower at Ostergarnsholm Island (Baltic Sea) during one week, while calculations using bulk formulations of fluxes were done with measurements in the tower and in two buoys moored at different locations. Different behaviors are found for the different fluxes. Measured latent heat flux shows higher correlation with calculations than measured sensible heat flux. For the CO2 flux, this relation was not found. Also all measured fluxes at the tower agree better with calculations when they are done under unstable conditions, meaning that the tower is better measuring the area where the measurements are taken in the buoys (near the tower). The studied period includes an upwelling and a high horizontal surface heterogeneity was found during most of the periods. It was seen using the comparison between calculated and measured fluxes and also using satellite images of the studied site. The footprint area is the area at some distance upwind from the tower where the surface conditions are influencing the measurements of the flux of some quantity at certain height in the tower, and this footprint area is continuously changing because its highly dependence with the stratification. Since during all the period the stratification was changing from slightly stable to slightly unstable conditions, the surface heterogeneity can also be seen in the variability of measured fluxes at different heights. One important conclusion in the study is that calculations of the fluxes using bulk formulations may not be useful when high variability of different parameters (as sea surface temperature and pCO2w ) is expected, as for example during upwelling situations and near coast, where the phytoplankton can significantly influence the concentration of CO2 at the surface. A wide study is done, including meteorological and oceanographic parameters, fluxes, comparisons, relations with parameters, transfer coefficients, dependences with the stratification and satellite images.Mätningar av flöden (impuls, värme, vattenånga och CO2) vid två olika höjder studerades med data från en mast på ön Östergarnsholm (i Östersjön) under en vecka, beräkningar av flödena gjordes med mätningar av atmosfäriska parametrar från samma mast samt data från två bojar på två olika platser. Man fann olika beteenden för de beräknade och uppmätta flödena. Direkt (sensibelt) värme visade högre korrelation mellan beräkningar och uppmätta sensibla värmeflöden . För CO2- flödet fann man inte detta samband. För alla flödena överensstämmer mätningarna bättre med beräknade flöden när de är gjorda under instabila förhållanden, vilket betyder att under dessa förhållanden representerar mätningarna i masten bättre området där bojarna är placerade. Den studerade perioden inkluderar en period med upvällning (upwelling) och en hög horisontell variabilitet i ytparametrar under den största delen av denna period. Detta visades genom jämförelser mellan de beräknade och de uppmätta flödena och även genom satellitmätningar. Det område uppvind masten där ytan påverkar flöden uppmätta i masten på en viss nivå kallas ”footprint area”, och denna footprint area förändras kontinuerligt på grund av det stora beroendet av skiktningen i atmosfären. Eftersom skiktningen under hela perioden förändrades från något stabilt till något instabilt, kan ytvariabiliteten även ses i variationen av uppmätta flöden på olika höjder. En viktig slutsats i studien är att beräkningar av flödena som görs med standardformler inte bör användas vid förhållanden med hög horisontell och vertikal variation av olika parameter (som havsytetemperatur och pCO2w), som till exempel under uppvällningssituationer och nära kusten, där phytoplankton markant kan påverka koncentrationen av CO2 vid ytan. Studien inkluderar meteorologiska, oceanografiska parametrar, flöden, samband med parametrar, överförings koefficienter, beroende av stabilitet och satellitbilder.
Flujos turbulentos (momento, calor sensible, calor latente y CO2) en 2 alturas diferentes fueron estudiadas usando medidas de una torre en la Isla de Östergarnsholm (Mar Báltico) durante una semana. Los flujos también fueron calculados usando formulaciones con medidas de la torre y de dos boyas ancladas en diferentes localizaciones. Diferentes características para los distintos flujos fueron encontradas. El flujo de calor latente muestra una relación más alta con los cálculos que el flujo de calor sensible. No se encontró esta relación para el flujo de CO2. También, todos los flujos medidos en la torre coinciden mejor con los flujos calculados cuando estos son hechos bajo condiciones de estratificación inestable, significando que la torre mide mejor el área donde son cogidas las medidas en las boyas (cerca de la torre). El periodo estudiado incluye un afloramiento costero y se encontró una alta heterogeneidad horizontal en la superficie del mar durante la mayoría de los periodos. Esto fue estudiado usando las comparaciones entre flujos calculados y medidos y también usando imágenes de satélite. El footprint area puede ser definido como el área a una distancia desde la torre hacia donde sopla el viento donde las condiciones de la superficie influyen las medidas del flujo de alguna cantidad en la torre, y este footprint area está continuamente cambiando debido a su alta dependencia con la estratificación. Durante todo el periodo la estratificación estuvo cambiando desde ligeramente estable a ligeramente inestable, y por ello la heterogeneidad de la superficie puede ser vista en la variabilidad de los flujos medidos a diferentes alturas. Una conclusión importante en este estudio es que los cálculos de los flujos usando formulaciones podrían no ser útiles cuando se espera una alta variabilidad de los diferentes parámetros (temperatura superficial del mar y pCO2w), como por ejemplo durante situaciones de afloramiento y también cerca de costa, donde el fitoplancton puede influenciar significativamente la concentración de CO2 en la superficie. Se presenta un amplio estudio, incluyendo parámetros meteorológicos y oceanográficos, comparaciones de flujos, relaciones con parámetros, coeficientes de transferencia, dependencias con la estratificación e imágenes de satélite.
2
Ho, Clara Wing-chung, et 何劉詠聰. « A study of the concepts of women's "talent" and "virtue" during the early and high Qing periods = ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B44569580.
Texte intégral
3
Fattahi, Sadegh, et Philip Månsson. « Computational and experimental study of fuel leakage through a ventilation valve during various driving conditions ». Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-159194.
Texte intégralRésumé :
Fuel leakage through a fill limit vent valve (FLVV) inside a fuel tank is an important factor to consider during the design of a new tank. The performance of the carbon canister which absorbs the hydrocarbon can be compromised if fuel manages to escape through the valve, so called Liquid Carry Over (LCO) and thus not fulfilling the fuel emission requirements. As of today this is not thoroughly investigated using experiments nor Computational Fluid Dynamics. The main focus of this study was to develop a method to simulate the behaviour of the FLVV during various driving conditions at an early design stage and if this gives rise to fuel escaping through the FLVV. This method was later to be validated with an experimental set-up and later used to perform some simulations to investigate LCO by varying different parameters such as fuel level and different types of driving. What happens when the canister is purging was also investigated to see if it has a pronounced effect on LCO. Purging is when hydrocarbons, absorbed by the canister, are sent to the engine and giving rise to an under pressure in the tank.The method was developed to run on a cluster utilizing 200 Central Processing Unit Cores where each simulated physical second required an average of 3 hours of simulation time.The flow inside the tank was simulated using a Volume Of Fluid (VOF) multiphase model and the dynamic behaviour of the floater inside the FLVV was simulated using an overset mesh with a Dynamic Fluid Body Interaction.The movement of the simulated dynamic floater was validated with an experimental set-up specifically developed for the overset mesh validation and the motion of the floater was captured at a fairly accurate level.A prototype for an experimental tank was also developed and produced to validate the VOF set-up used for sloshing inside the tank which was utilized on the real tank but due to time limitation the experiments were not performed. The results from the parameter investigation showed that LCO was present in cases with high fuel level inside the tank 95 % and that an aggressive driving gives rise to a higher level of LCO compared to normal driving. Simulations with a fuel level of 85 % and lower showed no evidence of LCO for this particular tank model. The purging of the tank induced a pumping effect giving rise to a higher level of LCO pumped through by the floater.
4
Kirby, Mark Samuel. « An experimental and theoretical study of the ice accretion process during artificial and natural icing conditions ». Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/17199.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO.
Bibliography: leaves 128-129.
by Mark Samuel Kirby.
M.S.
5
Wilson, A. F. « Electrostatic field conditions arising during the pumping of charged liquids into plastic tanks : An experimental and computational study ». Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372608.
Texte intégral
6
Peraza, Ávila Jesús Enrique. « Experimental study of the diesel spray behavior during the jet-wall interaction at high pressure and high temperature conditions ». Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/149389.
Texte intégralRésumé :
[EN] The potential of diesel engines in terms of robustness, efficiency and energy density has made them widely used as power generators and propulsion systems. Specifically, fuel atomization, vaporization and air-fuel mixing, have a fundamental effect on the combustion process, and consequently, a direct impact on pollutant formation, fuel consumption and noise emission. Since the combustion chamber has a limited space respect to the spray penetration, wall impingement is considered to be a common event in direct injection diesel engines, having a relevant influence in the spray evolution and its interaction with both surrounding air and solid walls. This makes of spray-wall interaction an important factor for the combustion process that is still hardly understood.
At cold-start conditions, the low in-chamber pressures and temperatures promote the deposition of fuel in the piston wall, which leads to a boost in the formation of unburned hydrocarbons. Additionally, modern design trends such as the increment of rail pressures in injection systems and the progressive reduction of the engine displacement, favor the emergence of spray collision onto the walls. In spite of the evident relevance of the comprehension of this phenomenon and the efforts of engine researchers to reach it, the transient nature of injection process, its small time scales and the complexity of the physical phenomena that take place in the vicinity of the wall, make challenging the direct observation of this spray-wall interaction. Even though computational tools have proven to be priceless in this field of study, the need for reliable experimental data for the development of those predictive models is present.
This thesis is aimed to shed light on the fundamental characteristics of spray-wall interaction (SWI) at diesel-like chamber conditions. A flat wall was set at different impingement distances and angles respect to the spray. In this way, two different kinds of experimental investigations on colliding sprays were carried out: A transparent quartz wall was employed into the chamber to, in isolation, analyze the macroscopic characteristics of the spray at both evaporative inert and reactive conditions, which have been observed laterally and through the wall, thanks to the use of a high-pressure and high-temperature vessel with optical accesses. This same test rig was used in the second kind of experiments, where instead of the quartz plate, a stainless steel wall was used to capture the effect of the operating conditions on the heat flux between the wall and the spray during the injection-combustion events and to determine how spray and flame evolution are affected by realistic heat transfer situations. This wall was instrumented to control its initial in-chamber surface temperature and to measure its variation with time by using high-speed thermocouples. Tests at free-jet conditions were also performed in order to provide a solid comparative base for those experiments.[ES] El potencial de los motores diesel en términos de robustez, eficiencia y la densidad de energía los ha hecho ser ampliamente usados como generadores de energía y sistemas propulsivos. Específicamente, la atomización de combustible, vaporización y mezcla de aire y combustible tienen un efecto fundamental en el proceso de combustión y, en consecuencia, un impacto directo en la formación de emisiones contaminantes, consumo de combustible y generación de ruido. Dado que la cámara de combustión tiene un espacio limitado con respecto la capacidad de penetración del chorro, el impacto de la pared se considera bastante común en motores de inyección directa diésel, que tienen una influencia relevante en la evolución del chorro y su interacción con el aire circundante y las paredes sólidas. Esto hace de interacción chorro-pared, un factor importante para el proceso de combustión que aún es dificilmente comprendido. En condiciones de arranque en frío, las bajas presiones y temperaturas en la cámara promueven la deposición de combustible en la pared del pistón, lo que conduce a un aumento en los niveles de formación de hidrocarburos no quemados. Además, las tendencias modernas de diseño como el incremento de las presiones de rail en los sistemas de inyección y la progresiva reducción en la cilindrada de los motores, favorecen la aparición de colisiones entre chorro y pared. A pesar de la evidente importancia en la comprensión de este fenómeno y los esfuerzos de los investigadores para alcanzarla, la transitoria naturaleza del proceso de inyección, sus pequeñas escalas de temporales y la complejidad de los fenómenos físicos que tienen lugar en las proximidades de la pared, hacen que la observación directa de esta interacción chorro-pared sea un desafío. Aunque las herramientas computacionales han demostrado ser invaluables en este campo de estudio, la necesidad de datos experimentales confiables para el desarrollo de esos modelos predictivos está muy presente. Esta tesis tiene como objetivo arrojar luz sobre las características fundamentales de la interacción chorro-pared (SWI por sus siglas en inglés) en condiciones de cámara similares a las de un motor diesel. Se colocó una pared plana a diferentes distancias de impacto y ángulos con respecto al jet. De esta manera, dos tipos diferentes de investigaciones experimentales sobre chorros en colisión se llevaron a cabo: se empleó una pared de cuarzo transparente en la cámara para, de forma aislada, analizar las características macroscópicas del chorro en condiciones evaporativas inertes y reactivas, que pueden observarse lateralmente y a través de la pared, gracias al uso de una instalación de alta presión y alta temperatura ópticamente accesible. Esta misma instalación se utilizó en el segundo tipo de experimentos en los que se introdujo una pared de acero inoxidable para capturar adicionalmente el efecto de las condiciones de operación en el flujo de calor entre ésta y el chorro durante los eventos de inyección y combustión y para determinar cómo la evolución del chorro y la llama son afectadas por una situación realista de transferencia de calor. Esta pared fue instrumentada para controlar la temperatura inicial de su superficie expuesta a la cámara y medir su variación con el tiempo, utilizando termopares de alta velocidad. Ensayos en condiciones de chorro libre también se realizaron para proporcionar una base comparativa sólida para esos experimentos.
[CA] El potencial dels motors dièsel en termes de robustesa, eficiència i la densitat d'energia els ha fet ser àmpliament usats com a generadors d'energia i sistemes propulsius. Específicament, l'atomització de combustible, vaporització i barreja d'aire i combustible tenen un efecte fonamental en el procés de combustió i, en conseqüència, un impacte directe en la formació d'emissions contaminants, consum de combustible i generació de soroll. Atès que la cambra de combustió té un espai limitat pel que fa la capacitat de penetració de l'raig, l'impacte de la paret es considera bastant comú en motors d'injecció directa dièsel, que tenen una influència rellevant en l'evolució del doll i la seva interacció amb el aire circumdant i les parets sòlides. Això fa d'interacció doll-paret, un factor important per al procés de combustió que encara és difícilment comprès. En condicions d'arrencada en fred, les baixes pressions i temperatures a la cambra promouen la deposició de combustible a la paret del pistó, el que condueix a un augment en els nivells de formació d'hidrocarburs no cremats. A més, les tendències modernes de disseny com l'increment de les pressions de rail en els sistemes d'injecció i la progressiva reducció en la cilindrada dels motors, afavoreixen l'aparició de col·lisions entre el doll i la paret. Tot i l'evident importància en la comprensió d'aquest fenomen i els esforços dels investigadors per aconseguir-la, la transitòria naturalesa de l'procés d'injecció, les seves petites escales de temporals i la complexitat dels fenòmens físics que tenen lloc en les proximitats de la paret , fan que l'observació directa d'aquesta interacció doll-paret siga un desafiament. Tot i que les eines computacionals han demostrat ser invaluables en aquest camp d'estudi, la necessitat de dades experimentals fiables per al desenvolupament d'aquests models predictius està molt present. Aquesta tesi té com a objectiu donar llum sobre les característiques fonamentals de la interacció doll-paret (SWI per les seues sigles en anglès) en condicions de cambra similars a les d'un motor dièsel. Es va col·locar una paret plana a diferents distàncies d'impacte i angles pel que fa al jet. D'aquesta manera, dos tipus diferents d'investigacions experimentals sobre dolls en col·lisió es van dur a terme: es va emprar una paret de quars transparent a la cambra per, de forma aïllada, analitzar les característiques macroscòpiques del doll en condicions evaporació inerts i reactives, que poden observar lateralment i a través de la paret, gràcies a l'ús d'una instal·lació d'alta pressió i alta temperatura òpticament accessible. Aquesta mateixa instal·lació es va utilitzar en el segon tipus d'experiments en els quals es va introduir una paret d'acer inoxidable per capturar addicionalment l'efecte de les condicions d'operació en el flux de calor entre aquesta i el dull durant els esdeveniments d'injecció i combustió i per determinar com l'evolució del doll i la flama són afectades per una situació realista de transferència de calor. Aquesta paret va ser instrumentada per controlar la temperatura inicial de la seua superfície exposada a la càmera i mesurar la seua variació amb el temps, utilitzant termoparells d'alta velocitat. Assajos en condicions de doll lliure també es van realitzar per proporcionar una base comparativa sòlida per a aquests experiments.
Peraza Ávila, JE. (2020). Experimental study of the diesel spray behavior during the jet-wall interaction at high pressure and high temperature conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149389
TESIS
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Hilmersson, Markus, et Erik Malmgren. « A Study to Examine During what Market Conditions it has been Profitable with Home Bias for a Swedish Fund Manager ». Thesis, KTH, Matematisk statistik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229049.
Texte intégralRésumé :
This thesis in applied statistics and industrial economics examines the correlation between a number of market conditions on the Swedish and Global market and the yield difference between the Swedish stock market and the Global stock market. The report is based on data from the index MSCI Sweden Net Return, MSCI World Net Return and the Volatility index S&P 500. The market conditions that have been examined are Bull markets, Bear markets, periods of high volatility. We also examined how the appreciation of the SEK in comparison to the USD and the yield of the Swedish stock market correlated with the yield difference between the Swedish Stock Market and the Global stock market. The correlation was examined using multiple linear regression. The results indicated a positive correlation between the yield difference between the Swedish stock market and the Global stock market and the yield of the Swedish stock market, the appreciation of the SEK compared to the USD and Bull markets. We found a negative correlation with Bear markets and no correlation at all with the volatility. The results are in line with what could be expected and give a stronger statistical ground for the idea that the Swedish stock market has larger fluctuations than the Global stock market during large-scale market fluctuations.Detta kandidatexamensarbete inom tillämpad matematik och industriell ekonomi syftar till att undersöka hur avkastningsdifferensen mellan den Svenska och Globala aktiemarknaden korrelerar med ett antal olika marknadsförhållanden. Rapporten är baserad på data från MSCI Sweden Net Return och MSCI World Net Return samt Volatilitetsindex S&P500. De marknadsförhållanden som har undersökts är Bull markets, Bear markets, perioder då det råder hög volatilitet på marknaden. Vi undersökte även avkastningsdifferensens korrelation till kronans värdeförändring gentemot den Amerikanska dollarn och korrelationen till den Svenska aktiemarknadens värdeökning. Korrelationen undersöktes genom att utföra en multipel linjär regression. Resultaten visade på en rådande positiv korrelation mellan utvecklingen på den Svenska aktiemarknaden, prisutvecklingen av den Svenska kronan mot Amerikanska dollarn samt under Bull markets. Vi fann även en negativ korrelation med Bear markets och ingen korrelation till volatiliteten. Resultaten är i linje med vad som kunde förväntas och ger en starkare statistisk grund till att den Svenska aktiemarknaden har större svängningar än den Globala aktiemarknaden vid stora marknadsfluktuationer.
8
Le, Chau Ho An. « Cross-border financial linkages and international financial contagion : an empirical study of East Asia during the 2007-2011 global financial crisis ». Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4455/.
Texte intégralRésumé :
Motivated by the global financial market turbulence in 2007-2011 and the gaps from the literature, this thesis presents an econometric assessment of different transmission mechanisms that propagated and amplified shocks from advanced economies to East Asia. The asset price channel is investigated with MS-VAR model and multivariate unconditional correlation tests. The recursive bivariate probit models are applied to test the liquidity shock transmission via the sudden stop in international lending. The second round effects are examined with partial adjustment models and system GMM estimation. The econometric procedure and testing approach bring about novel results from superior estimation techniques and handle several statistical problems such as heteroskedasticity, non-linearity, endogeneity, omitted variables, simultaneous equations and sample selection bias. The main finding of the thesis is that despite relatively sound fundamentals and limited exposure to structured credit products, East Asia could not totally decouple from the global financial crisis. Specifically, the asset price channels propagated volatility spillovers from the US and Europe to East Asian equity, foreign exchange and CDS markets. While international volatility spillovers were mainly caused by fundamental links, international behaviour during the shocks intensified the regional linkages and generated contagion effect. There was also contagion evidence associated with the sudden stop in international lending which facilitated the transmission of liquidity tensions in the interbank markets. Finally, contagion was magnified by the second round effects, defined as the feedback loops from the sudden changes in macro-financial conditions which caused adverse adjustment in bank performance. These findings have useful implications for international investors and policy authorities regarding to portfolio diversification and systematic risk containment.
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Tye, Angela Judith. « Conditional strategies to study gene function during gonadal development in mammals ». Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1445133/.
Texte intégralRésumé :
Sexual development in mammals involves a complex cascade of genetic events. These begin with a cell fate decision, whether to make Sertoli or follicle cells, that gives rise to the development of a male or female gonad, which is controlled by the testis-determining gene Sry. Following the expression of Sry, genes involved in the male pathway act to reinforce and maintain testis-specific cell fate decisions, as well as to repress the female pathway. Sox9 becomes rapidly upregulated after the onset of Sry expression, and is expressed in Sertoli cells throughout life. From mutation studies, SOX9 is known to be essential for male development in humans and to initiate Sertoli cell differentiation in mice. However, the function of SOX9 after sex determination and the reason for its maintenance in Sertoli cells remains unknown. In order to understand the function of Sox9 in the fetal and adult mouse testis, new tools have been generated to control gene activity in a conditional manner. This thesis mainly describes strategies to control either deletion of misexpression of Sox9. To make the tools useful at different stages, the tamoxifen-inducible Cre/loxP system was employed. This involves the establishment of two elements: a "Cre-driver" and a ' Sox9-responder". Cre-driver transgenes were made under the control of several gonadal-specific regulatory elements, as well as a strong, ubiquitous promoter. Responder mice allow Cre activated conditional misexpression or deletion of Sox9. Analyses on gonad morphologies and gene expression levels were compared between animals that have altered Sox9 expression and those that have not. The results reveal that Sox9 is necessary and sufficient for the expression of Sfl in the Sertoli cells, and suggest that Sox9 is antagonistic to the ovarian- specific gene Foxl2. The newly established Cre-drivers can also be applied in functional studies involving other genes implicated in sexual development.
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Farough, Aida. « An experimental study on characterization of physical properties of ultramafic rocks and controls on evolution of fracture permeability during serpentinization at hydrothermal conditions ». Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/76669.
Texte intégralRésumé :
Serpentinization is a complex set of hydration reactions, where olivine and pyroxene are replaced by serpentine, magnetite, brucite, talc and carbonate minerals. Serpentinization reactions alter chemical, mechanical, magnetic, seismic, and hydraulic properties of the crust. To understand the complicated nature of serpentinization and the linkages between physical and chemical changes during the reactions, I performed flow-through laboratory experiments on cylindrically cored samples of ultramafic rocks.
Each core had a well-mated through-going tensile fracture, to investigate evolution of fracture permeability during serpentinization. The samples were tested in a triaxial loading machine at an effective pressure of 30 MPa, and temperature of 260°C, simulating a depth of 2 km under hydrostatic conditions. Fracture permeability decreased by one to two orders of magnitude during the 200 to 340 hour experiments. Electron microprobe and SEM data indicated the formation of needle-shaped crystals of serpentine composition along the walls of the fracture, and chemical analyses of sampled pore fluids were consistent with dissolution of ferro-magnesian minerals. The rate of transformation of olivine to serpentine in a tensile fracture is calculated using the data on evolution of fracture permeability assuming the fracture permeability could be represented by parallel plates. Assuming the dissolution and precipitation reactions occur simultaneously; the rate of transformation at the beginning of the experiments was ~ 10-8-10-9 (mol/m2s) and decreased monotonically by about an order of magnitude towards the end of the experiment. Results show that dissolution and precipitation is the main mechanism contributing to the reduction in fracture aperture. The experimental results suggest that the fracture network in long-lived hydrothermal circulation systems may be sealed rapidly as a result of mineral precipitation, and generation of new permeability resulting from a combination of tectonic and crystallization-induced stresses may be required to maintain fluid circulation.
Another set of flow through experiments were performed on intact samples of ultramafic rocks at room temperature and effective pressures of 10, 20 and 30 MPa to estimate the pressure dependency of intact permeability. Porosity and density measurements were also performed with the purpose of characterizing these properties of ultramafic rocks.
The pressure dependency of the coefficient of matrix permeability of the ultramafic rock samples fell in the range of 0.05-0.14 MPa-1. Using porosity and permeability measurements, the ratio of interconnected porosity to total porosity was estimated to be small and the permeability of the samples was dominantly controlled by microcracks. Using the density and porosity measurements, the degree of alteration of samples was estimated. Samples with high density and pressure dependent permeability had a smaller degree of alteration than those with lower density and pressure dependency.Ph. D.
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Shumskykh, Mykyta. « Release of trace elements from contaminated sediments into surface waters during sediments dynamics : an experimental study ». Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4008.
Texte intégralRésumé :
Dans les systèmes aquatiques, la plupart des éléments traces métalliques (ETM) sont piégés dans les sédiments puis peuvent être relargués en fonction des conditions chimiques et de l’activité microbienne à l’interface eau-sédiment. L’objectif de cette étude était d’évaluer l’impact de remise en suspension des sédiments (lors de crues et d’opérations de gestion de barrages) sur la mobilité de certains ETM. Plusieurs conditions expérimentales de lessivage ont été choisies pour simuler ces événements : conditions oxiques et anoxiques sur des sédiments bruts et d’autres irradiés par rayons gamma. L’utilisation d’eau désionisée a permis de maximiser le processus de relargage. Deux types de sédiments, issus de contextes différents, ont été sélectionnés : le barrage de Villerest (France) et la rivière Xiang (Chine). Des expériences à long terme (30 jours) ont permis d’identifier la dégradation de la matière organique, l’activité microbienne et l’altération (voire la dissolution) de phases porteuses d’ETM comme principaux facteurs de contrôle. L’importance de l’activité microbienne n’a pas pu être quantifiée puisque l’irradiation n’a pas stérilisé totalement les sédiments. Enfin, l’impact de tels évènements parait très limité puisque moins de 1% des ETM contenus dans les sédiments ont été libérésIn aquatic systems, most of trace metals (TM) are buried in sediments and then can be released according to chemical conditions and microbial activity occurring at the sediment-water interface. The aim of this study was to assess the impact of resuspension events (flood or maintenance operations for dam reservoir) on the mobility of some TM. Different batch experiment conditions were chosen to mimic those events: under oxic and anoxic conditions on raw sediments and on gamma-irradiated ones (“sterilized” one). The use of deionized water allowed maximizing the release process. Two sediment types issued from different contexts were selected: the Villerest dam reservoir (France) and the Xiang River (China). Long term experiments (30-day long) allowed identifying that organic matter degradation, microbial activity and alteration/dissolution of trace metal bearing phases were the main controlling factors. The gamma-irradiation did not sterilize sediments but only limited aerobic bacteria and enhanced anaerobic activity. The impact of such 24h resuspension event on reservoir waters and downstream biota is very limited as less than 1% of trace elements was released
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Kezic, Jelena Marie. « A study of the monocyte-derived cell populations of the uveal tract and retina in homeostatic conditions and during the early stages of ocular autoimmune disease ». University of Western Australia. School of Anatomy and Human Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0084.
Texte intégralRésumé :
The eye contains closely related but widely different tissues, offering a unique opportunity to investigate the phenotype and function of monocyte-derived cell populations within functionally unique microenvironments in a single complex organ. The uveal tract and retina contain rich networks of immune cells that reside and traffic through the eye, these cells having been implicated in various ocular inflammatory processes and immune-mediated diseases. One such inflammatory condition is human posterior uveitis, an autoimmune disease mainly affecting the retina. As current treatments for posterior uveitis only serve to slow down disease progression, studies using animal models, namely, experimental autoimmune uveoretinitis (EAU), have focused on determining the key cellular and molecular mediators involved in disease initiation in order to expand the potential for novel therapeutic applications. The overall purpose of experiments in this thesis was to explore monocyte-derived cell populations of the uveal tract and retina, this being achieved by utilising a novel transgenic mouse model. Cx3cr1gfp/gfp transgenic mice on both BALB/c and C57Bl/6 backgrounds contain an enhanced green fluorescent protein (eGFP) encoding cassette knocked into the Cx3cr1 gene, disrupting its expression but facilitating GFP expression under the control of the Cx3cr1 promoter. Heterozygous (Cx3cr1+/gfp) mice were generated by crossing Cx3cr1gfp/gfp mice to wild-type (WT) mice. This transgenic model allowed for the exquisite visualisation of Cx3cr1-bearing monocyte-derived dendritic cells (DC) and macrophages in ocular tissues, whilst also enabling the investigation of a potential role for Cx3cr1 in recruiting monocyte-derived cells to the eye in steady-state and inflammatory conditions.
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李顯偉. « 明清之際的捕役與基層社會治安= A study of local constable and the maintaining of order in local society during the Ming-Qing transition ». HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/490.
Texte intégralRésumé :
中國歷代政府均視地方治安為重要的政治議題，治安議題也就成為治史者瞭解古代中國政治運作的一門路徑。過去有關「明清基層社會與治安」的研究，向為中外學者頗感興趣的課題。本文的重點是討論明清之際基層社會的治安管理情況，為此提出了四個既是獨立但又環環相扣的問題。有別於過往研究，本文將以捕役這類普遍存在於明清基層社會，而又備受現今學者忽略的基層公務員為切入點，首先重新梳理他們在明清之際出現的原因以及演變過程，解釋他們在明中後期才成為專門的治安人員，並釐清包括捕役在內的應捕人專責維持社會秩序。其次, 闡述捕役在基層社會中的職能，指出他們擁有頗大的治安和司法權力。接著討論捕役機制存在待遇差劣以及人手編排不足等制度性問題，因而促使捕役濫用職權，從而達到經濟和治安目的。至於捕役犯罪情節的內容和影響，本文摒棄傳統以小說內容入手的做法，改以多部判牘內有關捕役犯罪的真實個案着手，得出「誣良為盜」和「屈打成招」是他們最常見的犯罪行為的結論，這些罪行對基層社會的治安和司法運作造成重大問題。最後把焦點從治安人員轉移到管理這些群體的地方官員上，透過地方官員對待捕役的態度，反映官員在治安管理上的困難和理解。他們一方面面對統治者的治安要求，另一方面又受制度上及資源上的限制，所以只能以加重懲罰的高壓方法來提高捕役完成治安任務的可能和減低他們犯罪的機會。這種態度表層意義反映他們只視捕役為「治安工具」，更深層意義是揭示地方官員對治安管理的終極理解──完成治安任務。要言之，本文透過捕役以及管理這些治安人員的地方官員，帶出地方治安管理的政策和問題，以另一個角度，瞭解明清之際基層社會的治安情況和特色。study focuses on the social public order and management of the local society during the Ming-Qing transition. Four independent but related questionsare raised for discussions to achieve such aims. First of all, this thesis focuses onthe buyi (捕役, literally local constables). They were a type of grass-root civilservant which permeates the local society of the Ming-Qing period, but long beenignored by the modern historians. In order to understand how they becameindispensable public security staffs and to clarify their responsiblities, their rolesand deeds in the transition period between Ming and Qing, as well as theirtransformation process in the due course are discussed. Secondly, the functions ofbuyi in the local society are explored to point out the great power on security andjudicial aspect they had seized. After that the institutional issues including a lackof manpower and low remuneration level are discussed, as such issues had pushedthe buyi to misuse their power to seek for their own benefits. The third questionrelated to the criminal committed by the buyi. In this chapter the crimes of thebuyi are reconstructed from judicial casebooks rather than the late Ming novels.From such cases the most common crimes of those buyi are fallen into thecatergories of Accused on innocent person and Tortured for confessions . Suchcrimes were serious problem to the local judiciary as well as the social order. Atlast our focus is shifted from those local security staff to those local officials. Inorder to reveal the difficulties and understanding on maintaining local social orderfrom the viewpoint of officials, how they treated those buyi is thoroughlydiscussed. On one hand the officials had to obey the nationwide policies imposedto them by the imperial authority, on the other hand they were restricted by thelocal institutions and resources, therefore the officials could only raise the level ofpenalties so as to lower the possibility of those buyi to commit crimes, and also toimprove their willingness to fulfil their duty. Such difficulties of the officialsmade them to treat the buyi as tools for social order maintenance . Incidentally, itrevealed that the ultimate understanding of Ming-Qing local officials on socialorder maintenance was to accomplish on surface their missions of social orderissued from their seniors, other than establish solutions to uproot sources ofcrimes or to build an effective and uncorrupted force of local constables.To conclude, this thesis asks us to pay attention to the policies and issues onlocal social order of late imperial China by exploring the buyi and the localofficials whom managing them.
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Retamales, Roberto. « A study of semi-intensive shrimp culture in Ecuador in relation to physical, chemical and biological conditions in the production ponds during El Nino and La Nina events (1996 to 1999) ». Thesis, University of Stirling, 2002. http://hdl.handle.net/1893/3286.
Texte intégralRésumé :
Once every three, four or even seven years, the Southeast trade winds which blow west-ward across the tropical zone of the Pacific Ocean, from the shores of South America towards the Asian land mass, weaken and sometimes even reverse their direction. This phenomenon is known as El Nino. Conversely, the climatic condition known as La Nina is characterised by unusually cold ocean temperatures in the equatorial Pacific, as compared to El Nino. Global climate anomalies associated with La Nina tend to be opposite to those of El Nino. A study of shrimp culture in Ecuador was carried out to analyse the temporal changes in pond water quality, phytoplankton composition and diversity, and bacterial composition and diversity in the intestines of cultured Litopenaeus vannamei in Ecuador. These parameters were studied in relation to their impact on the growth, survival and production in a semi-intensive shrimp culture farm situated in the Chone River Estuary, Ecuador. Five culture periods were studied during the climatic events of El Nino, La Nina and transition periods (1996 to 1999 ). Shrimp were stocked in ponds at 10 PL/m2. Pond management included pond drying, inorganic fertilisation, and feeding with a commercial pellet twice a day. The physicochemical characteristics of the pond water and the phytoplankton and bacterial counts were estimated at intervals of 7-15 days of culture during each period of study. The concentrations of nitrite, nitrate, sulphide, ammonia, pH and suspended solids in the pond water in all ponds during the five culture periods fluctuated within ranges considered compatible with shrimp farming. Phosphorus, silica, temperature and salinity, however, showed significant differences during the five periods of shrimp culture, reaching sub-optimal levels during some culture periods. The species composition and diversity of phytoplankton was different during El Nino, La Nina events and transition periods, with a decrease in the diatom community and an increase in the cyanophytes algae community associated with changes in nutrients and nutrient ratios, and temperature, salinity is discussed. A low diversity of bacterial genera with a predominance of Vibrio spp., particularly V. harveyi and V. parahaemolyticus, was observed in shrimp intestines during disease outbreaks in the transition and La Nina periods associated with significant environmental changes in temperature and salinity. Shrimp performance was significantly different between El Nino, La Nina and transition climatic periods. Survival, feed conversion ratio and yield were better during El Nino periods because of the positive effects of higher pond water temperature and salinity (29°C and 28 psu) on the shrimp stocks.
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Leigh, Sasha Naomi Bharier. « A study of the dynamics of the British Ice Sheet during Marine Isotope Stages 2 and 3, focusing on Heinrich Events 2 and 4 and their relationship to the North Atlantic glaciological and climatological conditions / ». St Andrews, 2007. http://hdl.handle.net/10023/525.
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Millard, Mary J. (Mary Jennifer). « A Comparative Study of the Trends of Comedy and Non-Comedy Television Genres and the Public's Attitudes Toward Economic Well-Being, According to a Survey of Gallup Polls, During a Thirty-Year Period from 1955- 1984 ». Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc500781/.
Texte intégralRésumé :
This study is concerned with the problem of whether the public's attitudes toward economic well-being could be compared with the types of television programs made popular over a thirty-year period. Two measures were used to determine the public's attitudes toward economic well-being: 1) answers to questions of an economic nature; and 2) answers to questions that asked what was the most important problem. All data were compiled from Gallup polls administered during 1955 through 1984. The television genre data were compiled from sources by Brooks and Marsh, McNeil and Norback and Broadcasting magazine. No association existed among the three measures.
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Brown, P., et B. Russell. « Weather Conditions during the 1991 Growing Season ». College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/208613.
Texte intégralRésumé :
The 1991 growing season was characterized by a cool, wet spring and a cool, dry summer. Heat unit accumulation for the season was the lowest in 5 years at most locations. Precipitation was concentrated in two periods: early (Jan. - Mar.) and late (Nov. - Dec.). Summer rainfall was well below normal at most locations.
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Brown, P., et B. Russell. « Weather Conditions during the 1992 Growing Season ». College of Agriculture, University of Arizona (Tucson, AZ), 1993. http://hdl.handle.net/10150/209330.
Texte intégralRésumé :
Abundant rainfall was the most prominent feature of the 1992 growing season. Monthly precipitation totaled above normal during the first five months of the year, and during August and December. Warm temperatures accompanied the wet weather during the spring planting season and helped boost growing season heat unit totals to near record levels in central and western Arizona. Early fall weather was warm and dry which provided excellent conditions for both finishing the crop and preparing the crop for harvest.
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Uwamahoro, Jean Claude. « Single station TEC modelling during storm conditions ». Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1020325.
Texte intégralRésumé :
It has been shown in ionospheric research that modelling total electron content (TEC) during storm conditions is a big challenge. In this study, mathematical equations were developed to estimate TEC over Sutherland (32.38⁰S, 20.81⁰E), during storm conditions, using the Empirical Orthogonal Function (EOF) analysis, combined with regression analysis. TEC was derived from GPS observations and a geomagnetic storm was defined for Dst ≤ -50 nT. The inputs for the model were chosen based on the factors that influence TEC variation, such as diurnal, seasonal, solar and geomagnetic activity variation, and these were represented by hour of the day, day number of the year, F10.7 and A index respectively. The EOF model was developed using GPS TEC data from 1999 to 2013 and tested on different storms. For the model validation (interpolation), three storms were chosen in 2000 (solar maximum period) and three others in 2006 (solar minimum period), while for extrapolation six storms including three in 2014 and three in 2015 were chosen. Before building the model, TEC values for the selected 2000 and 2006 storms were removed from the dataset used to construct the model in order to make the model validation independent on data. A comparison of the observed and modelled TEC showed that the EOF model works well for storms with non-significant ionospheric TEC response and storms that occurred during periods of low solar activity. High correlation coefficients between the observed and modelled TEC were obtained showing that the model covers most of the information contained in the observed TEC. Furthermore, it has been shown that the EOF model developed for a specific station may be used to estimate TEC over other locations within a latitudinal and longitudinal coverage of 8.7⁰ and 10.6⁰ respectively. This is an important result as it reduces the data dimensionality problem for computational purposes. It may therefore not be necessary for regional storm-time TEC modelling to compute TEC data for all the closest GPS receiver stations since most of the needed information can be extracted from measurements at one location.
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Henslin, Kayla B. « Rapidity of response to hypoxic conditions during exercise / ». Connect to online version, 2009. http://minds.wisconsin.edu/handle/1793/45116.
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Wanner, Daniel. « Controlling over-actuated road vehicles during failure conditions ». Doctoral thesis, KTH, Fordonsdynamik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166819.
Texte intégralRésumé :
The aim of electrification of chassis and driveline systems in road vehicles is to reduce the global emissions and their impact on the environment. The electrification of such systems in vehicles is enabling a whole new set of functionalities improving safety, handling and comfort for the user. This trend is leading to an increased number of elements in road vehicles such as additional sensors, actuators and software codes. As a result, the complexity of vehicle components and subsystems is rising and has to be handled during operation. Hence, the probability of potential faults that can lead to component or subsystem failures deteriorating the dynamic behaviour of road vehicles is becoming higher. Mechanical, electric, electronic or software faults can cause these failures independently or by mutually influencing each other, thereby leading to potentially critical traffic situations or even accidents. There is a need to analyse faults regarding their influence on the dynamic behaviour of road vehicles and to investigate their effect on the driver-vehicle interaction and to find new control strategies for fault handling. A structured method for the classification of faults regarding their influence on the longitudinal, lateral and yaw motion of a road vehicle is proposed. To evaluate this method, a broad failure mode and effect analysis was performed to identify and model relevant faults that have an effect on the vehicle dynamic behaviour. This fault classification method identifies the level of controllability, i.e. how easy or difficult it is for the driver and the vehicle control system to correct the disturbance on the vehicle behaviour caused by the fault. Fault-tolerant control strategies are suggested which can handle faults with a critical controllability level in order to maintain the directional stability of the vehicle. Based on the principle of control allocation, three fault-tolerant control strategies are proposed and have been evaluated in an electric vehicle with typical faults. It is shown that the control allocation strategies give a less critical trajectory deviation compared to an uncontrolled vehicle and a regular electronic stability control algorithm. An experimental validation confirmed the potential of this type of fault handling using one of the proposed control allocation strategies. Driver-vehicle interaction has been experimentally analysed during various failure conditions with typical faults of an electric driveline both at urban and motorway speeds. The driver reactions to the failure conditions were analysed and the extent to which the drivers could handle a fault were investigated. The drivers as such proved to be capable controllers by compensating for the occurring failures in time when they were prepared for the eventuality of a failure. Based on the experimental data, a failure-sensitive driver model has been developed and evaluated for different failure conditions. The suggested fault classification method was further verified with the conducted experimental studies. The interaction between drivers and a fault-tolerant control system with the occurrence of a fault that affects the vehicle dynamic stability was investigated further. The control allocation strategy has a positive influence on maintaining the intended path and the vehicle stability, and supports the driver by reducing the necessary corrective steering effort. This fault-tolerant control strategy has shown promising results and its potential for improving traffic safety.QC 20150520
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Bennett, Alec. « Measurement of atmospheric electricity during different meteorological conditions ». Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493966.
Texte intégralRésumé :
The Earth's atmosphere is continually electrified. Our understanding of the global atmospheric electrical circuit has improved since its discovery in the early twentieth century, although this area of geophysics still provides both theoretical and experimental scientific challenges. The variability of the electric field and current density measured at the surface is attributed to meteorological sources, both global and local in origin. By investigating the variability in electrical parameters under different atmospheric conditions, these global and local sources can be separated. As a consequence, information on global thunderstorm and shower cloud activity can be retrieved, which is of direct relevance to research on global climate change.
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Asher, Mohit Hemant, et Alexander Lönnergård. « Objective evaluation of vehicle handling during winter conditions ». Thesis, KTH, Fordonsdynamik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180279.
Texte intégralRésumé :
Vehicle handling evaluation is a crucial part of the vehicle development process. The evaluation can be done in two ways, subjectively; by expert test drivers or objectively; by performing repeatable standard manoeuvres usually by steering robots. Subjective testing is resource intensive as prototypes need to be built. Objective testing is less so, as it can be performed in a virtual environment in conjunction with physical testing. In an e˙ort to reduce resources and time used in vehicle development, manufacturers are looking to objective testing to assess vehicle behaviour.Vehicle handling testing in winter strongly relies on subjective testing. This thesis aims to investigate into the usage of objective test strategy to assess vehicle handling behaviour in winter conditions. Manoeuvres and metrics are defined for summer con-ditions, but not for winter. Hence the goal was to define new or modified metrics and manoeuvres custom to winter testing.Data from an objective winter test was obtained and analysed. The manoeuvres used were constant radius (CR), frequency response (FR), sine with dwell (SWD) and throt-tle release in turn (TRIT). The manoeuvres were compared to public standards from the International Organization for Standards (ISO) and National Highway Traÿc Safety Administration (NHTSA) as well as the vehicle manufacturer standards.The data from a reference vehicle is compared to that from three configuration vehicles, one without anti-roll bar in the front, one without rear anti-roll bar and a standard. The di˙erence in the signals between reference and configuration vehicles is compared to the spread in data of the reference vehicle to determine the signal-to-noise ratio in the manoeuvres. The spread of reference data is analysed to determine the distribu-tion and to di˙erentiate between the two test days. To replicate vehicle behaviour in simulation, winter tyre models using brush and Magic Formula model equations were investigated. These were used in a bicycle and a VI-CarRealTime model. The perfor-mance of these are checked and compared. The bicycle model is used in an unscented Kalman filter, to investigate potential improvements in signal processing. The metrics obtained from the study of standards are checked for robustness in winter conditions by analysis of variance (ANOVA) methods. The procedure of selection of metrics from the ANOVA results is explained. Further, the manoeuvres are modified virtually in VI-CarRealTime, from the results of a sensitivity analysis. The di˙erence in metrics between reference and configuration vehicles is maximized.The final results of the thesis were; a test plan with modified manoeuvres and a set of robust metrics. Also containing important information to aid in the execution of the tests. The conclusions drawn were that the noise in winter testing is high, but the di˙erence between vehicles is statistically significant for some robust metrics. The metrics related to yaw rate were in general more robust. Open-loop throttle and steering control in manoeuvres should be avoided as far as possible. A bicycle model is not complex enough to represent vehicle behaviour at high slip angles. Performance increase of a UKF is not justified as to the e˙ort involved.
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Green, Charles W. « Possible contributions of lid conditions during explosive cyclogenesis ». Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23351.
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Hamburger, Thomas. « Aerosol microphysical properties during anticyclonic flow conditions over Europe ». Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-127766.
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Wallace, Melissa Laura. « The psychological impact of conditions altering appearance during adolescence ». Thesis, University of the West of England, Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438792.
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Attravanam, Siddarth Kashyap. « Identifying Operating Conditions of Tires During Highway Driving Maneuvers ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534456018582412.
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Wodausch, Jens. « Investigation and prediction of autoignition during hot start conditions ». Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/991.
Texte intégralRésumé :
This Master’s thesis discusses the investigation of autoignition (knock) of air-fuel mixtures in internal combustion engines (type EA 827; 1.6 and 1.4 l) under hot start conditions. Chapter Three comprehensively reviews literature on fuel characteristics; specifically boiling point, chemistry and the difference between the Research and Motor Octane Number (RON and MON). Furthermore different types of autoignition are discussed with regards to their detection and assessment in the chapter. The subsection on engine management looks at possible methods of altering and eliminating autoignition. Chapter Four details the equipment used to obtain data and measurements, as well as the signal conditioning of the spark and injector signal. Chapter Five discusses the actual results obtained during summer testing of the different methods of altering and eliminating autoignition in an internal combustion engine, as derived from the theories presented in Chapter Three. The summer tests finally verified the new application level and showed that only a reduction in the quantity of fuel injected can eliminate autoignition. However, a slight decrease in heat release does cause an increase in start time. In Chapter Six, based on the test results, a simulation model which calculates the probability of autoignition in a 1.4 l (Econo) engine during hot start conditions in Matlab/Simulink was developed. This simulation model satisfactorily verified test results.
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Khalefa, Baled Ibrahim Noufal [Verfasser]. « Opioid receptor efficacy during normal and pathological conditions / Baled Khalefa ». Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1046563831/34.
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Babins, Leonard H. (Leonard Howard). « Nonverbal communication patterns in siblings during prosocial and agonistic conditions ». Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41318.
Texte intégralRésumé :
This study investigated nonverbal communication patterns in siblings in the prosocial, neutral, and agonistic conditions. Sixty-four children aged 3 years 3 months to 9 years 6 months (16 same-gender and 16 mixed-gender sibling dyads) participated. All children's behaviors were coded using the system for Identifying Affect Expressions by Holistic Judgments (AFFEX, facial expressions) and the Behavioral Coding System (BCS) for behaviors. The major finding was that all children were as likely to imitate positive facial expressions in the prosocial as in the aggressive conditions. However, they were more likely to imitate positive behaviors in the prosocial condition and negative behaviors in the aggressive condition. Age within the dyad was the most important subject factor affecting imitation of positive facial expressions and positive and negative behaviors. Younger children tended to imitate their older siblings more than the reverse. Gazing at the older siblings' nonverbal behaviors (NVBs) was an important precursor during both prosocial and aggressive play situations. Of paradigmatic importance is the finding on dyad-gender effects that all-female dyads imitated positive facial expressions as part of their communication during aggressive play.
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Mdyusoff, Zainuddin. « Feldspar dissolution during the weathering of granite under tropical conditions ». Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/11854.
Texte intégralRésumé :
Much of Malaysia is composed of granite. Samples ranging from unweathered granite to surface soils from newly exposed cut slopes and drill-holes were analysed using Quantitative X-ray Powder Diffraction (QXRPD), X-ray Fluorescence spectrometry (XRF), Inductively-coupled plasma mass spectrometry (ICP-MS), Scanning Electron Microscopy (SEM) and Optical microscopy. Samples were also sent to commercial laboratories for the determination of geotechnical engineering index and strength properties. The analyses have brought about a categorization of the weathering profiles into 4 ‘zones’: top soil, saprolite, weathering boundary and unweathered granite zones. The reactions within the active weathering boundary zone dictate the formation of secondary minerals. The findings in each different zone have enlightened the understanding of the development of secondary minerals especially clays in a deep weathering profile. The study also confirms and furthers understanding of the way chemical weathering occurs on the K-feldspar grains and is followed by the mechanical collapse of the grains leading to the reduction in the geotechnical strength of the material. The major element mobility study did not show any relation to the degree of weathering within the saprolite. Trace element study did not give conclusive results. However, a rare earth element (REE) study shows that the mobility of REE depends on the degree of weathering. The presence of clay minerals and feldspar grains are related to the geotechnical engineering properties, especially the strength properties which are responsible to the stability of slopes.
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Docherty, Lorraine. « Molecular detection and gene expression of Campylobacter during stress conditions ». Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/843004/.
Texte intégralRésumé :
The magnetic immuno-polymerase chain reaction assay (MIPA), was developed for the detection of Campylobacter jejuni and Campylobacter coli initially in milk and chicken products. After 18 hours pre-enrichment the MIPA could detect 420 cfu g-1 of chicken and 63 cfu ml-1 of artificially contaminated milk. MIPA was then applied for the detection of C. jejuni / C. coli in cloacal swabs and in retail poultry, where the sensitivity was found to be comparable to cultural methods. However, results were available significantly faster, within 24 hours compared to the 4-5 days of cultural methods. MIPA was also evaluated as a technique for the detection of "viable but non-culturable" (VBNC) forms in the environment. It was found that there was a reduction in sensitivity for the detection of these non-culturable forms (NCFs) and it was concluded that the MIPA had limited use in their detection. The lack of sensitivity of MIPA for detecting VBNC campylobacters in the environment may indicate that they are either antigenically or genetically distinct from the culturable forms. This result highlights the question of whether these VBNC forms actually represent a viable potentially infectious form of Campylobacter. This question can be answered at a molecular level; promoter activity can be monitored as a representation of viability of the bacterial cell during stress conditions. The promoter activity could be measured using a promoter probe vector. Initially we decided to construct a promoter probe vector which based on the recombinase system of the PI bacteriophage. However, the final construct was unstable and due to the constraints of time we decided to use a pre-existing promoter probe vector pSP73 constructed by Purdy and Park, (1993). This promoter probe vector contains promoterless luxAB genes which induce light emission as a reporter of gene expression. In order to investigate the genetic regulation during the conversion of C. jejuni to non-culturable forms (NCFs), we monitored gene expression during the transformation of C. jejuni into the non-culturable state. The promoterless copy of the luxAB genes was placed under the control of promoter regions of the C. jejuni flaA gene. Transformed C. jejuni was incubated under stress conditions that induce transition to NCFs (Non-culturable forms). Promoter activity, plate counts and direct microscope counts were simultaneously monitored. It was found that during the initial conversion of C. jejuni to NCFs there is an up-regulation of the flaA promoter. This regulation occurs in response to agitation and did not occur in NCFs and indicates that they are functionally non-viable.
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Muhic, Dino. « High consistency refining of mechanical pulps during varying refining conditions : High consistency refiner conditions effect on pulp quality ». Thesis, Linköping University, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15082.
Texte intégralRésumé :
The correlation between pulp properties and operating conditions in high consistency (HC) refiners at Holmen Paper AB were studied. Two types of HC refiners were investigated: the Andritz RTS refiner at the Hallstavik Mill and the Sprout-Bauer Twin 60 refiner at the Braviken Mill. The objective of the study was to clarify the relationship between the pulp properties and refining conditions such as electrical energy input, housing- and feed- pressure and plate wear in high consistency refining.
The results of this project show that worn segments reduce the operating energy maximum input and the pulp and handsheet properties in negative aspects such as lower tensile- and tear index, and shorter average fibre length. Energy input is an important factor in the refining process and influence Canadian Standard Freeness and the tensile index as evident from the probability residuals. Housing pressure and feed pressure influence the pulp quality and should be adjusted in order to optimise the refining process, although the effect is not as great as for energy input or plate wear.
The results of the study indicate that Braviken Mill is operating at its optimum for the parameters measured in this project. Hallstaviks goal, to avoid fibre shortening and to obtain better tensile index, can be reached by making slight changes in pressure condition.
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Sevimli, Melike Kadriye. « Optimization Of Processing Conditions During Halogen Lamp-microwave Baking Of Cakes ». Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605326/index.pdf.
Texte intégralRésumé :
The main objective of this study was to optimize processing conditions
during halogen lamp-microwave combination baking of cake by using Response
Surface Methodology. It was also aimed to compare quality of products baked in
microwave-halogen lamp combination oven, halogen lamp oven, microwave oven
and conventional oven.
In the first part of the study, as independent variables, baking time for
conventional ovenmicrowave power and baking time for microwave oven
halogen lamp power and baking time for halogen lamp oven and microwave power, halogen lamp power and baking time for halogen lamp-microwave combination oven were used. Weight loss, specific volume, firmness and color of the cakes were measured during the study. Cakes baked in conventional oven at 175°
C for 24 minutes were determined as the control cakes. Weight loss of cakes increased with increasing independent variables for all oven types. Specific volume and firmness of cakes increased with increasing microwave power, but decreased with upper halogen lamp power. Color formation was achieved in the combination baking but not as much as in the conventional baking. Response Surface Methodology was used to optimize the baking conditions in the second part of the study. Upper and lower halogen lamp powers, microwave power and baking time were used as independent variables. Optimum processing conditions were found as 60% for upper halogen lamp power, 70% for lower halogen lamp power, 30% for microwave power and 5 minutes for baking time. Cakes baked at optimum baking conditions had comparable quality with conventionally baked ones, except color. In short, by the usage of halogen lamp-microwave combination oven it was possible to obtain high quality cakes by reducing of conventional baking time about 79%.
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Zhang, Shiyu [Verfasser]. « Intermediates during the Formation of GaN under Ammonothermal Conditions / Shiyu Zhang ». München : Verlag Dr. Hut, 2014. http://d-nb.info/1060587947/34.
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Figueroa, Michael. « Dynamic Analysis of a Light Wood-Framed Structure during Fire Conditions ». Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-theses/777.
Texte intégralRésumé :
The purpose of this project is to create a theoretical dynamic analysis model to assess the dynamic response of light, wood-framed structures before and after fire conditions. This information is useful for predicting the damage to structural integrity due to a fire. The mass and stiffness matrices used for the dynamic model are derived from a standard residential building created for an existing project at WPI funded through the DHS/FEMA/USFA Assistance to Firefighters Grant program. The damping matrix is derived via the Rayleigh Damping Method using the mass and stiffness matrices obtained through SAP. Then, theoretical impact forces are applied to the developed dynamic model, and the acceleration response is estimated using Matlab. Both acceleration time history and frequency responses are used as the evaluation method. Finally, the dynamic model is integrated with a fire simulation model to investigate the impact of fire conditions on dynamic responses of residential buildings. The results show that frequencies can shift due to the structural degradation due to fire.
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Bertelson, Rachel Samantha. « Symptom Changes in Children and Adolescents With Internalizing Conditions During Treatment ». ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/4040.
Texte intégralRésumé :
Mental health conditions, such as internalizing disorders, in children and adolescents have been attributed to higher than expected levels of high school dropouts, juvenile crimes, and suicide. Previous research studies provide limited information on factors influencing treatment success for children and adolescents diagnosed with internalizing disorders. This study utilized a nonequivalent comparison group design gathered from an archived data set from a sample of children and adolescents (N = 215) who participated in an intensive outpatient managed mental health care treatment program. Self-report data were retrieved from previous responses to the Children's Depression Inventory and Revised Children's Manifest Anxiety Scale - Second Edition to explore factors related to treatment effectiveness for children and adolescents with internalizing symptoms. Data were analyzed using a mixed model repeated measures ANOVA to analyze main effects and interactions. This analysis identified if gender, ethnicity, age group, and treatment duration were risk factors related to symptom amelioration or deterioration for children and adolescents diagnosed with internalizing disorders across time. Females with internalizing disorders reported significantly higher levels of depression symptom change than males with internalizing disorders. All other results did not show any statistically significant relationships. Results suggest that therapists should consider gender-related factors when providing treatment to children and adolescents with internalizing disorders. Active clinical research epitomizes the belief of social change by putting research to practice and utilizing available tools to predict predictive risk in the treatment of children and adolescents.
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Theron, Nicolas Charle. « Medical conditions and illness in elite football players during international competition ». Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/9034.
Texte intégralRésumé :
Includes bibliographical references (leaves 121-128).Background: Previous clinical research of football players participating in international tournaments has mainly focussed on documentation of injuries and risk factors for injury. However, despite anecdotal evidence that medical symptomatology, illness and medical complaints are common during travel to international competitions, the epidemiology of medical conditions before, during or after elite level football tournaments, has not been well documented. Objective: The aims of the research presented in this dissertation were: 1) to determine the prevalence of medical conditions in elite football players 2) to determine the incidence and nature of medical conditions and illness in the elite football players participating in an international tournament (2009 FIFA Confederations Cup tournament) and 3) to provide data for the medical planning and management of elite football players during future events. Methods: The first component of this dissertation consisted of a comprehensive review of the current literature describing the prevalence and incidence of medical conditions and illness in athletes. The original research component of this dissertation consisted of two parts, and both studies were conducted during the FIFA Confederations Cup tournament, which was held in South Africa in June 2009. All the players in the 8 participating teams (23 players per team – a total of 184 players) were approached by the FIFA Medical Assessment and Research Centre (F-MARC) through their team physicians and invited to participate as research subjects in the studies. Part 1 (descriptive cross-sectional study): Prior to the tournament, all the players completed a previously validated medical history and illness questionnaire. Furthermore, the questionnaire contained sections on player demographics, training history, medication and supplement use, life-style history, family history of atopy, current and past history of medical conditions and detailed sections pertaining to upper respiratory tract infections (URTI), allergies, asthma, exercise associated muscle cramping (EAMC) and history of previous surgery. Part 2 (prospective cohort study): During the 15 days of the tournament each team physician was requested to complete a daily injury, medical illness and treatment log for each player. Finally, data on the environmental conditions at each venue were collected, as recorded by the South African Weather Service. Results: The main findings in part 1 of this study were: 1) exercise associated muscle cramping (EAMC) was the most prevalent medical condition reported, with 64 (46%) of the players reporting a history of EAMC, 2) the prevalence of allergy was 27 (20%) and asthma 6 (4%), 3) the prevalence of dermatological conditions was 16 (12%), 4) the prevalence of gastro-intestinal conditions was 10 (7%) and central nervous system conditions was 6 (4%), 5) URTI one week before the tournament was reported by 7 (5%) of the players, 6) 68 (49%) of the players reported a history of previous surgery and 7) 72 (52%) of the players reported the use of supplements or vitamins and 11 (8%) the use of medication. Knee surgery was the most common anatomical area operated with 33 (24%) of the players reporting previous knee surgery. This was followed by a much lower prevalence of ankle surgery, 8 (6%). In part 2 of the study, a total of 56 injuries and 35 illnesses were recorded during the tournament. The main findings in this study were: 1) an overall injury rate of 64.4 injuries per 1000 match hours or 2.1 injuries per match, 2) an overall rate of 2.7 injuries and 1.7 illnesses per 100 player days, 3) that 0.88 days were lost per injury and 0.46 days were lost per illness, 4) the lower limb was the most commonly injured body part, 5) 11 (20%) of the injuries reported were to the thigh, 6) 15 (44%) of the injuries reported were due to a contusion, 6) 13 (37%) of the illnesses reported were due to ENT conditions, and 7) 7 (20%) were due to respiratory tract symptoms. Summary and conclusion: Illness and injury are common during an international football tournament. The pattern of injury was similar to that previously reported. However, the novel finding of this dissertation was that illness is a significant component to the medical care to a travelling team and needs to be considered by team physicians managing the medical needs of elite football teams.
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Huang, Charlie Chia Wei. « Regulation of Cat-1 gene transcription during physiological and pathological conditions ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1270242874.
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Almeida, Luis Pedro. « Swash zone dynamics of coarse-grained beaches during energetic wave conditions ». Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3837.
Texte intégralRésumé :
Coarse-grained beaches, such as pure gravel (PG), mixed sand-gravel (MSG) and composite (CSG) beaches, can be considered as one of the most resilient non-cohesive morpho-sedimentary coastal environments to energetic wave forcing (e.g., storms). The hydraulically-rough and permeable nature of gravel (D50 > 2 mm), together with the steep (reflective) beach face, provide efficient mechanisms of wave energy dissipation in the swash zone and provide a natural means of coastal defence. Despite their potential for shore protection very little is known about the response of these environments during high energetic wave conditions. Field measurements of sediment transport and hydrodynamics on coarse-grained beaches are difficult, because there are few instruments capable of taking direct measurements in an energetic swash zone in which large clasts are moving, and significant morphological changes occur within a short period of time. Remote sensing methods emerge in this context as the most appropriate solution for these types of field measurement. A new remote sensing method, based around a mid-range (~ 50 m) 2D laser-scanner was developed, which allows the collection of swash zone hydrodynamics (e.g., vertical and horizontal runup position, swash depth and velocity) and bed changes on wave-by-wave time scale. This instrument allowed the complete coverage of the swash zone on several coarse-grained beaches with a vertical accuracy of approximately 0.015 m and an average horizontal resolution of 0.07 m. The measurements performed with this new methodology are within the accuracy of traditional field techniques (e.g. video cameras, ultrasonic bed-level sensors or dGPS). Seven field experiments were performed between March 2012 and January 2014 on six different coarse-grained beaches (Loe Bar, Chesil, Slapton, Hayling Island, Westward Ho! and Seascale), with each deployment comprising the 2D laser-scanner together with complementary in-situ instrumentation (e.g., pressure transducer, ADV current meter). These datasets were used to explore the hydrodynamics and morphological response of the swash zone of these different environments under different energetic hydrodynamic regimes, ranging from positive, to zero, to negative freeboard regimes. With reference to the swash zone dynamics under storms with positive freeboard regimes (when runup was confined to the foreshore) it was found that extreme runup has an inverse relationship with the surf scaling parameter (=2Hs /gTptan2). The highest vertical runup excursions were found on the steepest beaches (PG beaches) and under long-period swell, while lower vertical runup excursions where linked to short-period waves and beaches with intermediate and dissipative surf zones, thus demonstrating that the contrasting degree of wave dissipation observed in the different types of surf zones is a key factor that control the extreme runup on coarse-grained beaches. Contrasting morphological responses were observed on the different coarse-grained beaches as a result of the distinct swash\surf zone hydrodynamics. PG beaches with narrow surf zone presented an asymmetric morphological response during the tide cycle (accretion during the rising and erosion during the falling tide) as a result of beach step adjustments to the prevailing hydrodynamics. On dissipative MSG and CSG beaches the morphological response was limited due to the very dissipative surf zone, while on an intermediate CSG beach significant erosion of the beach face and berm was observed during the entire tide cycle as a result of the absence of moderate surf zone wave dissipation and beach step dynamics. Fundamental processes related to the link between the beach step dynamics and the asymmetrical morphological response during the tidal cycle were for the first time measured under energetic wave conditions. During the rising tide the onshore shift of the breaking point triggers the onshore translation of the step and favors accretion (step deposit development), while during the falling tide the offshore translation of the wave breaking point triggers retreat of the step and favours backwash sediment transport (erosion of the step deposit). Under zero and negative freeboard storm regimes (when runup exceeds the crest of the barrier or foredune), field measurements complimented by numerical modelling (Xbeach-G) provide clear evidence that the presence of a bimodal wave spectrum enhances the vertical runup and can increase the likelihood of the occurrence of overtopping and overwash events over a gravel barrier. Most runup equations (e.g., Stockdon et al., 2006) used to predict the thresholds for storm impact regime (e.g., swash, overtopping and overwash) on barriers lack adequate characterisation of the full wave spectra; therefore, they may miss important aspects of the incident wave field, such as wave bimodality. XBeach-G allows a full characterization of the incident wave field and is capable of predicting the effect of wave spectra bimodality on the runup, thus demonstrating that is a more appropriate tool for predicting the storm impact regimes on gravel barriers. Regarding the definition of storm impact regimes on gravel barriers, it was found that wave period and wave spectra bimodality are key parameters that can affect significantly the definition of the thresholds for these different regimes. While short-period waves dissipate most of their energy before reaching the swash zone (due to breaking) and produce short runup excursions, long-period waves arrive at the swash zone with enhanced heights (due to shoaling) and break at the edge of the swash, thus promoting large runup excursions. When offshore wave spectrum presents a bimodal shape, the wave transformation on shallow waters favours the long period peak (even if the short-period peak is the most energetic offshore) and large runup excursions occur. XBeach-G simulations show that the morphological response of fine gravel barriers is distinct from coarse gravel barriers under similar overtopping conditions. While on coarser barriers overtopping regimes are expected to increase the crest elevation and narrow the barrier, on fine barriers sedimentation occurs on the back of the barrier and in the lower beach face. Such different sedimentation patterns are attributed to the different hydraulic conductivity of the different sediment sizes which control the amount of flow dissipation (due to infiltration) and, therefore, the capacity of the flow to transport sediment across and over the barrier crest. The present findings have significantly improved our conceptual understanding of the response of coarse-grained beaches during storms. A new field technique to measure swash dynamics in the field was developed during this thesis and has great potential to become widely used in a variety of coastal applications.
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Millar, Kristina K. « Antibiotic Efficacy and Interaction in Escherichia coli during Varying Nutrient Conditions ». Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/scripps_theses/809.
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Due to the recent rise in antibiotic resistant pathogens, and the difficulties surrounding the quest for new antibiotics, many researchers have started revisiting antibiotic interactions in hopes of finding new treatment options. The primary outcome of this project was to examine the efficacy of concomitant antibiotic use under varying nutrient conditions, to identify variations in antibiotic interactions. Antibiotic interactions were studied, utilizing E. coli as a model bacterial system, grown in four different media types. E. coli cultures were treated with streptomycin, tobramycin, erythromycin, and amikacin individually and in a pairwise fashion at varying doses. We found that at least some antibiotic efficacies were dependent on the environmental nutrient conditions E. coli was grown in, as the antibiotics were not equally effective in all media types. E. coli grown in potato dextrose broth, in particular, showed extremely high tolerance to antibiotic inhibition. In addition, we observed several variations in antibiotic interactions, depending on the combination of antibiotics and environmental conditions utilized. It is predicted that differences in available nutrients is the primary cause of the observed discrepancies in antibiotic properties between media. The observation of changes in antibiotic efficacy under different environmental and nutrient conditions has serious implications for use of antibiotic combinations as drug treatments. Not all microenvironments within the human body have identical nutrient make-up. If the interactions antibiotics are reported to have in one environmental condition change under another, reckless prescription of combinations could lead to a serious adverse reaction. Thus, this is an important area for future in vitro and in vivo research.
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Halonen, Kimmo. « Gamma spectrum analysis of fission product release during accidental conditions : focus on ruthenium release during air ingress ». Thesis, KTH, Fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103715.
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Hunter, E. J. « Behaviour and welfare of dry sows in different housing conditions ». Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384583.
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Clifton, Andrew James. « Wind tunnel investigations of boundary layer conditions before and during snow drift / ». Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17165.
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Pulkkinen, Antti. « Geomagnetic induction during highly disturbed space weather conditions : studies of ground effects / ». Helsinki : Finn. Meteorological Inst, 2003. http://www.gbv.de/dms/goettingen/373588518.pdf.
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Aquino, SeÌrgio Francisco de. « Formation of soluble microbial products (SMP) in anaerobic reactors during stress conditions ». Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405566.
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Louw, Francois G. « Performance trends of a large air-cooled steam condenser during windy conditions ». Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6593.
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Adams, Kenneth James. « Conditions influencing the spread of inasive crayfish during restoration and its consequences ». Thesis, Northern Arizona University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3621075.
Texte intégralRésumé :
In this dissertation, we explored three issues central to the understanding of the dynamics of the invasions of non-native crayfish. First, we investigated how the spread and abundance of non-native crayfish are influenced by biotic and abiotic factors, in the context of a river restoration project. Second, we tested whether roundtail chub, an Arizona native fish, demonstrate as much predatory pressure on invasive crayfish compared to small mouth bass, a non-native sports fish. Third, we investigated the consequences of crayfish spread by testing if crayfish reduce emerging aquatic insects.
In the first chapter, we examined the response of a spreading and invading non-indigenous crayfish population to a stream restoration project in travertine forming Fossil Creek, Arizona. We tested three predictions: 1) Increased flow would increase crayfish by providing more shallow riffles and backwater areas for juveniles. 2) Travertine deposition would decrease crayfish by cementing the substrate making it difficult for crayfish to burrow. 3) Changes in fish assemblage from non-native to native would reduce predation pressure on crayfish causing an increase in crayfish abundance. In contrast to our predictions there were no large increases in crayfish abundance following restoration. More detailed observations of different reaches, however, indicates that fish species and density exert some regulation over crayfish. Crayfish abundance decreased following restoration where exotic fish remain but slightly increased where they were removed. Additionally, areas in the river with increased travertine deposition had the largest declines following restoration. These observations suggest that crayfish abundance in this system is limited by substrate modification by travertine, to a lesser extent by predator regulation from fish, and interactions with flow.
In the second chapter, we compared the predatory effects of a native fish, roundtail chub (Gila Robusta), to the non-native, predatory smallmouth bass (Micropterus dolomieu) on the exotic northern crayfish (Orconectes virilis). The investigation occurred in Fossil Creek and addressed three questions: 1) Are native roundtail chub as effective predators on invasive juvenile crayfish as non-native smallmouth bass? 2) Will the removal of the bass have unexpected management implications due to increases in crayfish? 3) Is the benthic invertebrate community affected by differences in the assemblage of fish and crayfish? Two in-stream enclosure experiments tested the survival of juvenile crayfish in the presence of each of the two fish species with cage controls without fish. Crayfish abundance and benthic macroinvertebrates were compared between a section of the stream above a fish barrier where non-native species were removed to a section of stream directly below the barrier where they remained. The results of the enclosure experiments showed that non-native bass more strongly reduced juvenile crayfish than native roundtail chub. Crayfish abundance was also reduced in the stream reach containing bass compared to the reach composed of the native fish, despite similar environmental conditions. These results support the hypothesis that the native roundtail chub have reduced predatory pressure on crayfish abundance. Contrary to our predictions there were no significant differences in the benthic macroinvertebrate community suggesting that abiotic factors are more important than fish and crayfish in structuring this assemblage.
In the third chapter, we conducted two experiments using in stream enclosures to determine if the invasive crayfish Orconectes virilis in Arizona reduced the density and biomass of different groups of emerging aquatic insects. The two experiments occurred in different stream reaches that varied in geomorphic features and benthic community composition. One reach consisted of a riffle-pool morphology typical of many southwestern streams and an insect community composition dominated by dipterans. The other reach was characterized by travertine dam formation and a step-pool morphology with a more diverse benthic insect community. Crayfish had the greatest negative impact on the emergence density of mobile non-dipteran insect taxa and larger dipterans leading to declines in overall emergence biomass. Sedentary sediment dwelling taxa were relatively not impacted. We were not able to determine the exact mechanism of reductions but a disruption of insect colonization could have been due to either predation or dislodgement from the foraging activity of the crayfish. The large decline in biomass and a shift in insect emergence composition towards smaller bodied taxa rather than larger bodied taxa could have implications for insect predators in the riparian environment. Crayfish effects were not sensitive to reach differences in geomorphology or other environmental factors and were strikingly similar across both experiments. Relatively minimized impacts by high densities of crayfish indicated some type of density dependence or interference.
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Li, Yao Hou. « Modelling of boundary conditions and their effects during hot forging and rolling ». Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245646.
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Carruthers, Michael D. « Transcriptional analysis of Escherichia coli O157:H7 during in vivo mimicking conditions ». [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389094.
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