Heat stress and dehydration pose a severe challenge to physiological function and the capability to perform physical work. There is, however, limited knowledge on the regional haemodynamic and metabolic responses to strenuous exercise in environmentally stressful conditions. The primary aim of this thesis was to examine whether dehydration and heat stress compromise brain, muscle and systemic blood flow and metabolism, and whether depressed brain and muscle oxygen delivery underpin reduced exercise capacity during graded incremental and prolonged exercise. This thesis makes an original contribution to the knowledge by showing for the first time that dehydration markedly accelerates the decline in cerebral blood flow during maximal incremental (Chapter 4) and prolonged sub-maximal exercise (Chapter 5) in the heat. Cerebral metabolism, however, is preserved by compensatory increases in substrate extraction. Falling carbon dioxide tension underpinned the decline in CBF. However, a distinct regional distribution of blood flow across the head was observed, suggesting that different mechanisms are responsible for the regulation of regional blood flow within the head. A reduced cerebral metabolism is therefore an unlikely factor explaining the compromised exercise capacity in physiologically stressful hot environments. Rather, restrictions in active muscle blood flow and oxygen supply, which are not apparent during sub-maximal exercise, may explain the reduced maximal aerobic power in heat stressed conditions. For the first time we have manipulated skin and core temperature to show that combined internal and skin hyperthermia reduces maximal aerobic power in association with restrictions in limb, brain and systemic blood flow and skeletal muscle metabolism (Chapter 6). Overall, the findings of the present thesis provide novel information on how circulatory limitations across contracting skeletal muscle, brain and systemic tissues and organs might underpin the impairment in exercise capacity in physiologically taxing environments evoking significant dehydration and hyperthermia.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam. / Science, Faculty of / Zoology, Department of / Graduate

In normal tissues, blood supply is closely matched to tissue demand for wide ranges of oxygen demand and arterial pressure. This suggests that multiple mechanisms regulate blood flow. Theoretical models can be used to analyze these interacting mechanisms. One proposed mechanism for metabolic flow regulation involves the saturation-dependent release of ATP by red blood cells, which triggers an upstream conducted response signal and arteriolar vasodilation. To analyze this mechanism, oxygen and ATP levels are calculated along a flow pathway of seven representative segments, including two vasoactive arteriolar segments. The conducted response signal is dependent on ATP concentration. Arteriolar tone depends on the conducted response signal, local wall shear stress and wall tension. Arteriolar diameters are calculated based on vascular smooth muscle mechanics. The model can account for increases in perfusion consistent with experimental findings at low and moderate oxygen consumption rates despite the opposing effects of the myogenic and shear-dependent responses. Autoregulation, the maintenance of nearly constant blood flow as arterial pressure varies, is assessed in the presence or absence of the myogenic, shear-dependent and/or metabolic responses. The model results indicate that the combined effects of myogenic and metabolic regulation overcome the vasodilatory effect of the shear-dependent response to generate autoregulatory behavior. Capillary recruitment has been shown to increase the capacity for oxygen delivery during exercise. In the model, capillary density is assumed to depend on small arteriole diameter. The model predicts a significant increase in the range over which perfusion can be regulated when recruitment is included. Oscillations in diameter and tone are predicted under certain conditions, suggesting a novel mechanism for vasomotion. The conditions that give rise to oscillations are analyzed. It is shown that the appearance of oscillations depends in a complex way on a number of system parameters. In summary, the theoretical model provides a quantitative assessment of the myogenic, shear-dependent and metabolic responses that affect blood flow regulation and identifies a role for capillary recruitment and vasomotion in the control of blood flow.

The aim for this thesis is to explore the possibility to save both water and energy in showers. Through a quicker, more responsive and precise shower faucet using digital thermometers and stepper motors. A faucet has two input pipes with cold and hot water respectively. To reach a desired shower temperature; a single thermometer is needed, to measure the mixed water temperature. Using this information, two motors will control two valve until the desired temperature is reached. To maintain the desired temperature throughout the shower session, the temperature should be continuously monitored and when temperature disturbance occurs, the valves should compensate for it. To achieve this a demonstrator was made. The demonstrator uses stepper motors connected to valves to control the flow through a hot and cold water pipe. The system reads the temperature of the output water continuously and makes appropriate changes to the position of the valves. Due to safety concerns, no water was used in the testing of the demonstrator. The theoretical response time of the system is very short, and the demonstrator can theoretically change temperature of the mixed water by around 5°Celsius per second. / Syftet med denna rapport är att utforska möjligheterna att spara både vatten och energi till duschar, genom en snabbare, mer responsiv och mer exakt duschblandare. Detta ska uppnås genom användning av digitala termometrar och stegmotorer. Duschblandaren ska läsa temperaturerna av det blandade vattnet, och justera respektive kran tills önskad temperatur är uppnådd. För att bibehålla önskad temperatur kommer temperaturen kontinuerligt övervakas. När störningar i temperatur uppkommer ska duschblandaren kompensera för det, och därmed hallå en konstant temperatur. För att åstadkomma detta byggdes en demonstrationsenhet. Denna demonstrationsenhet använder stegmotorer kopplade till kranar för att kontrollera flödet genom ett varmt och ett kallt vattenrör. Systemet läser konstant temperaturen av det blandade vattnet och gör lämpliga ändringar av kranarnas positioner. På grund av säkerhetsrisk användes inget vatten vid testning av demonstrationsenheten. Den teoretiska responstiden av systemet är mycket kort, och demonstrationsenheten kan teoretiskt ändra temperatur av det blandade vattnet med en hastighet av ungefär 5°Celsius per sekund.

Dans les thylakoïdes des végétaux supérieurs, la réaction photochimique de la photosynthèse implique un transfert d’électrons linéaire ayant lieu entre les photosystèmes II et I et aboutit à la production de pouvoir réducteur (NADPH) et d’ATP. En parallèle à ce transfert linéaire, le transfert cyclique d’électrons autour du PS I court-circuite le PS II et fait intervenir distinctement les complexes PGR (PGR5/PGRL1) et NADPH déshydrogénase (NDH). Ces deux voies alternatives permettent la production d’ATP sans accumulation de NADPH dans le stroma et particulièrement en conditions de stress environnemental. Ces voies sont essentielles pour la physiologie de la plante mais leur régulation demeure mal connue. Une hypothèse a été émise quant à leur régulation redox en étudiant plusieurs thiorédoxines chloroplastiques. Des expériences menées in vivo et in vitro sur des mutants d’Arabidopsis, de tabac et de tomate ont mis en évidence le rôle très spécifique de la thiorédoxine m4 dans la régulation négative des voies dépendantes de PGR et NDH. Une stratégie originale a été mise en place pour capturer les cibles putatives de cette thiorédoxine en mutant le site actif de la protéine chez Arabidopsis. Les résultats obtenus ont montré l’existence de plus de 160 cibles potentielles et certaines d’entre elles pourraient être impliquées dans la régulation des voies dépendantes des complexes PGR et NDH. / In plants thylakoids, the photochemical reaction of photosynthesis implies a linear electron flow between photosystems II and I which produces reducing power (NADPH) and ATP. In addition of linear electron flow, the cyclic electron flow around PS I bypasses PS II and involves distinctly the PGR (PGR5/PGRL1) and the NADPH dehydrogenase (NDH) complexes. These two alternative pathways lead to the production of ATP without accumulation of NADPH in the stroma especially under environmental stress conditions. Both pathways are essential for the plant physiology but their regulation remains unclear. An assumption concerning a redox regulation has been considered by surveying several chloroplastic thioredoxins. In vivo and in vitro studies of Arabidopsis, tobacco and tomato mutants revealed that the m4 thioredoxin plays a very specific role in the down-regulation of the PGR and NDH dependant pathways. An original strategy to capture putative targets of this thioredoxin has been established by mutating the active site of the protein in Arabidopsis. The results showed the existence of more than 160 potential targets and some of them could be involved in the regulation of PGR and NDH dependant pathways.

During the migration season in 2013 a study on spawning migrating salmon and the effect of water flow on the behavior was conducted of the salmon at the Forshaga hydropower station in the River Klarälven. The River Klarälven with its nine hydropower plants on the Swedish side, constituting migration obstacles for the migrating salmon. Fortum Generation AB has together with the County Administrative Board restored a salmon trap at the lowermost hydropower station in Forshaga, aiming at making it possible for the salmon to swim into the trap, and thereafter be transported by truck past the power plants and then continue their journey to the spawning grounds on their own. Unfortunately, it is believed that the trap does not work as well as it should. In this study, I focused on salmon position in relation to water flow and if the number of salmon that swam into the fish trap differed between salmon with previous experience of the trap (experienced) and salmon without experience (unexperienced). My results showed that there were significantly more inexperienced salmon that entered the trap than experienced salmon. The salmon, regardless of experience, chose a position where the flow was highest. To increase catches of salmon in the fish trap I suggest that one use more attraction water and keep the trap open more hours. My results should be of interest to managers as the trap efficiency has never been evaluated, and no earlier studies about the effect of salmon experience on trap efficiency exist. / Vandringssäsongen 2013 genomfördes en studie på lekvandrande lax och hur vattenflödet påverkade laxens beteende vid Forshaga kraftstation i Klarälven. Klarälven med dess 9 vattenkraftverk på den svenska sidan utgör vandringshinder för den lekvandrande laxen. Fortum har tillsammans med Länsstyrelsen renoverat en laxfälla i det mest nedströms liggande kraftverket i Forshaga. Syftet med fällan är att laxen ska simma in i fällan till en uppsamlingsbassäng och därefter köras med lastbil förbi kraftverken, för att därefter fortsätta vandringen på egen hand. Fiskfällans effektivitet är ifrågasatt och man vet inte hur effektiv den är. I denna studie fokuserade jag på laxens ståndplats i relation till varifrån det huvudsakliga flödet kom, samt om antalet laxar som simmar in i fiskfällan skiljde sig mellan lax med tidigare erfarenhet av fällan (erfaren) och lax utan erfarenhet av fällan (oerfaren). Mina resultat visade att det var signifikant fler oerfarna laxar än erfarna laxar som simmade in i fällan. Laxen, oavsett erfarenhet, valde ståndplats där flödet var som högst. För att öka fångsterna av lax i fiskfällan skulle mer lockvatten och fler timmar då fällan är öppen kunna bidra med mer fångst. Denna studie borde vara av intresse för inblandade aktörer i laxens förvaltning eftersom fällans effektivitet aldrig utvärderats tidigare, och dessutom har man inte studerat om tidigare erfarenhet av en fälla påverkar laxen.

This work describes the modeling, synthesis, integration and characterization of a novel nanostructure embedded thermoresponsive material for microfluidic applications. The innumerable applications of thermoresponsive surfaces in the recent years have necessitated the development of a rigorous mathematical treatment for these surfaces to understand and improve their behavior. An analytical model is proposed to describe the transfer characteristic (variation of contact angle versus temperature) of a unique switchable, nanostructured, thermoresponsive surface consisting of silica nanoparticles and the thermoresponsive polymer, Poly(N-isopropylacrylamide ) (PNIPAAm) which changes its wetting angle upon heating. Important metrics such as the absolute lower critical solution temperature, threshold & saturation temperatures and gain are modeled and quantified by mathematical expressions. Based on the modeling, a heat source for the thermoresponsive surface was integrated on the glass substrate itself to create a fully functional smart surface. The design and fabrication of a smart platform consisting of the switchable, nanostructured, thermoresponsive surface with an integrated gold microheater for wettability control and its time response analysis was conducted. The insight gained into the behavior of the thermoresponsive surface by using the analytical model, aided the effort in the effective integration of the surface into a microfluidic channel for flow regulation applications. The implementations of novel microfluidic flow regulator concepts were tested. The aim is to integrate a regulator function to a channel surface utilizing the layer-by-layer (LBL) deposition technique. The characterization and pressure differential study of the microfluidic regulators was carried out on simple straight microchannels which were selectively coated with the thermoresponsive surface. Theoretical and experimental studies were performed to determine the important characteristic parameters including capillary, Weber and Reynolds numbers. The pressure differential data was used to develop critical operating specifications. This work lays out a new microfluidic device concept consisting of a channel with a built-in regulatory function.

La presente investigación evalúa el grado en que el dique-embalse Paso de las Piedras ha interrumpido la continuidad hidrológica del río Sauce Grande y cuantifica los impactos de la regulación hidrológica sobre el régimen de caudal, la morfología y la temperatura del agua del río aguas abajo del embalse. El trabajo de tesis presenta una evaluación integral y sistémica de los impactos del dique-embalse basada en el entendimiento de los procesos fluviales que ocurren aguas arriba del mismo. Además de proveer información sobre los impactos hidrológicos, morfológicos y térmicos de la construcción y operación del dique-embalse, este estudio genera nuevas series de datos climáticos e hidrológicos que proporcionan una importante plataforma sobre la cual basar futuras investigaciones de la cuenca del Sauce Grande. Por otra parte, este estudio implementa un marco metodológico aplicado al análisis hidro-geomorfológico de cuencas no aforadas que tiene un gran potencial de aplicación en otras cuencas de la región y en otras regiones semiáridas del mundo. / Despite the regional importance of the Sauce Grande River as main source for water supply and the large capacity of the Paso de las Piedras Reservoir, both the hydrology of the river basin and the effects of the impoundment on the river environment remain poorly evaluated. This study provides the very first assessment of the degree of flow regulation induced by the Paso de las Piedras Dam on the middle section of the Sauce Grande River, and quantifies its impacts on the hydrology, morphology and patterns of water temperature of the river downstream from the impoundment. In addition to providing new information on the response of regulated rivers to upstream impoundment and on the effects of impoundment on the Sauce Grande River specifically, this study generates spatial, climatic and hydrologic data and implements a methodological framework to hydrological assessment of ungauged basins. The methods include a set of procedures performed to generate data and a set of procedures performed to hydrological and morphological assessment. Methods used to generate data include (i) terrain modelling of the river basin, (ii) filling and modelling of climatic data, (iii) hydrological modelling of the upper river basin, and (iv) flow simulation and calculation. Methods used for hydrological and morphological assessment include (i) inspection of the water balance of the dam reservoir and quantification of the reservoir size-yield-performance relationships, (ii) quantification of the degree of hydrological alteration of the river downstream, (iii) classification of diurnal regimes of water temperature and quantification of their climatic sensitivity, and (iv) GIS-based diachronic analysis of change in the fluvial forms and the fluvial landscape. Results revealed that reservoir inflows are driven by varying climate conditions, whereas reservoir outflows are constrained by the dam purpose for water supply. Large volumes of water are yielded annually (73 % of the mean annual runoff) and the remaining volume is conserved within the reservoir for periods of drought. These patterns of flow regulation have seriously affected the hydrology and water quality of the river downstream. Floods were fully eliminated and the magnitude and frequency of high and low flows were reduced dramatically, with substantial increase in the duration of similar flow conditions. Furthermore, summer temperatures were depressed, winter temperatures were increased, and diurnal fluctuations were altered in both magnitude and timing. Analysis of the geomorphic response to altered hydrology revealed fluvial stability. Lateral and vertical channel activity was related to human intervention to facilitate the evacuation of dam outlets and spills more than to natural adjustments to reduced flow discharge and sediment load. The reduced flow, even if sediment-free, is incompetent to work its channel and at present, the downstream channel morphology is a relic of a fluvial environment created in the past under conditions of higher energy. The new climatic, hydrologic and morphologic information yielded herein has triple applicability: (i) it informs dam managers about the complex behaviour of the river system, (ii) it contributes to improve reservoir operation procedures while maintaining the overall integrity of the river system, and (iii) it provides a consistent scientific platform on which to base further research efforts conducting to an interdisciplinary framework of river restoration. Furthermore, the methods implemented in this research are widely transferable to hydrological assessment of ungauged basins worldwide, with special applicability to semiarid regions.