Syfte Syftet är att undersöka Per-Olof och Irma Åstrands tillvägagångssätt vid skapandet av det submaxirnala cykelergometertest som kallas "Åstrandstestet" samt att reflektera övertestets validitet och reliabilitet. Metod Studien är baserad på litteraturstudier samt en djupintervju med Per-Olof Åstrand. Samtal har förts med Sture Malmgren, en av författarna till boken Konditionstest på cykel samt med Per-Olof Åstrand för att undvika oklarheter. Resultat Vårt huvudfynd visar att vid den ursprungliga utformningen och framtagningen av det submaximala cykelergometertest som kallas Åstrandstestet, genomfördes flera submaximala tester där resultaten från försökspersonernas första test exkluderades. Alla personer som testas submaximalt med hjälp av Åstrandstestet så som det används idag, då resultaten från det första testet används, kan få ett felaktigt värde, I dagsläget finns inga studier som visar hur stort felet kan bli eftersom olika människor påverkas olika av exempelvis nervositet. Därför är det svårt för författarna till detta examensarbete att bedöma vilken betydelse exkluderingen av det första testet har för testets noggrannhet. Slutsats Om Åstrandstestet ska användas som metod för att uppskatta en persons maximala syreupptagningsförmåga är det av största vikt att det används på ett sätt som minskar felmarginalerna. För att uppnå detta bör man låta försökspersonen göra ett förtest för att vänja sig vid metod, utrustning och försöksledare.

Objective This study aimed to identify potential metabolic mechanisms including (1) neuromuscular inefficiency, (2) cardiovascular recovery deficits, or (3) both, in individuals with complaints of vocal fatigue.

Dans l'ouest de l'Europe, une grande importance est accordée à la composante sol dans l'élaboration des vins. La nutrition minérale est la principale voie par laquelle le sol peut avoir une influence sur la vigne et par conséquent sur le vin qui en est issu. Dès lors, ce travail de thèse appréhende la question plus large des transferts élémentaires entre le sol et la plante à travers de l'utilisation d'outils géochimiques en milieu viticole. Une combinaison de techniques impliquant des indicateurs classiques tels que les rapports élémentaires ou des bilans de masses ainsi que des traceurs plus innovants comme les rapports isotopiques du Cu et la résonance paramagnétique électronique (RPE) est utilisée. Dans un premier temps, l'influence du sol sur la composition élémentaire du vin a été étudiée dans plus que 200 vins provenant d'Allemagne, d'Espagne, de France, et d'Italie. A cette échelle, le type de sol (classé comme calcaire ou non-calcaire) et les conditions météorologiques apparaissent comme des critères discriminants. Par la suite, deux parcelles viticoles de Soave (Italie) aux sols contrastés ont été étudiées afin de d´déterminer l'influence du type du sol sur les vignes. Même si les sols présentent des propriétés pédologiques différentes, une pédogénèse complexe a induit des propriétés géochimiques similaires. Dans les vignes, les traceurs élémentaires et biochimiques montrent que la variabilité inter-annuelle et inter-individuelle est plus grande que la différence liée au sol lui-même. Néanmoins, il est possible de déterminer quel est le sol considéré par l'étude des rapports isotopiques du Sr. Parmi tous les nutriments et éléments toxiques généralement étudiés pour leur mobilité dans les sols, le cuivre a été suivi dans la dernière partie de cette thèse, essentiellement du fait de son épandage toujours massif comme fongicide en viticulture. En effet, les pesticides cupriques comme la bouillie bordelaise sont utilisés depuis environ 150 ans en viticulture. Le Cu s'accumule d`es lors dans les sols et les conséquences ´ecotoxicologiques en font un sujet de plus en plus sensible. Parmi les pesticides analysés dans notre étude, les rapports isotopiques du Cu varient autant entre les différents fongicides que dans les sols étudiés dans la littérature, rendant ainsi impossible l'utilisation de ces isotopes comme traceurs d'origine du Cu dans les sols. [...] / In western Europe, soil is of primordial importance for wine making. Soil qualities are often discussed and an influence on wine flavor is frequently inferred. However, evidence for a role of soil chemistry on wine composition and taste is scarce, but mineral nutrition of grapevine plants is one possible way of influence. This thesis approaches the complex question of elemental cycling between soil and plant through the use of geochemical tracers in vineyard environments. A combination of traditional tracers such as elemental ratios and mass balances as well as innovative tools such as Cu isotope analysis and electron paramagnetic resonance (EPR) are used on different observation scales. The influence of soil type on wine elemental composition was investigated using over 200 wine samples from France, Germany, Italy and Spain. Results of chemical analysis were then statistically linked to environmental conditions. At this scale, elemental contents of wine vary depending on soil type (calcareous or not), meteorological conditions, and wine making practice. To determine which soil properties can influence the chemical composition of grapevine plants, two vineyard plots on contrasted soils in Soave (Italy) were examined. Soil forming mechanisms were studied along two catenas and subsequently linked to elemental composition of grapevine plants and biochemical markers of plant health. Even though soil morphology was different, complex soil forming processes led to similar geochemical properties of soils. Differences in plant chemical compositions between soil types are small compared to inter-individual and inter-annual variability. However the use of Sr isotopic ratios allows the determination of the pedological origin of plants. In a next step, the fate of Cu pesticides in vineyard soils was studied. Cu-based pesticides have been used for almost 150 years in European vineyards and Cu accumulates in soils, so that the fate of Cu and its ecotoxicological implications are of growing importance. Therefore, Cu mobility in vineyard soils and transfer to grapevine plants were investigated using stable Cu-isotope ratios and EPR-measurements. Isotope ratios of Cu-based fungicides vary largely between products, covering Cu isotope ratios in soils reported in literature and thus making source tracing impossible. However, Cu isotope ratios are useful for tracing biogeochemical mechanisms of Cu transport in soils. The vertical transport of Cu in different soil types was investigated in the Soave vineyard using a combination of mass balance calculations, kinetic extractions and δ65Cu-isotope ratios. Results suggest that Cu can be transported to depth even in carbonated environments. Besides it is shown that heavy organic-bound Cu is lost from carbonated soil columns likely caused by dissolution of Cu carbonates by organic matter. [...]

Cette thèse porte sur les possibilités que les méthodes d’imagerie géoélectrique offrent à la fois pour la caractérisation des processus géochimiques mais aussi pour l’étude d’interaction sol-racines. La ligne conductrice de ce travail, repose sur la position centrale de la qualité des sols et des interactions racines-sols dans de nombreux problèmes environnementaux. En effet, un nombre croissant d’études rapportent l’importance des interactions mutuelles entre les racines et le sol. Dans cette optique, cette thèse explore l’utilisation le développements approfondis de méthodes géoélectriques. Les processus physico-chimiques ainsi que les interaction sol-racines sont à l’origine de mouvement d’eau et de soluté, d’altération de la structure des sols ainsi que de perturbations biologiques. Les méthodes géoélectriques sont potentiellement sensibles à ces modifications hydrologique et biochimique. La méthode de Polarisation Provoquée Spectrale (PPS) a été combinée avec des analyses et des modélisations géochimiques permettant de connaitre sa sensibilité à la composition du fluide interstitiel (contenu dans l’espace poral), du pH et de la force ionique. Plus particulièrement, la signature PPS de la substitution Na+/Cu2+ a été analysée car il s’agit d’un critère pertinent traduisant la qualité d’un sol et reconnu mondialement. L’analyse PPS a été réalisée sur un sable (silicate) saturé et pour des concentrations typiques de Na+/Cu2+ que l’on trouve classiquement dans des sols exposés à des utilisations de pesticides au Cuivre (Cu). Les résultats ont montré que le pH et la force ionique ont été les variables prépondérantes contrôlant le signal PPS, alors que des effets négligeables sont liés à la substitution Cu/Na. L’utilisation simultanée d’analyses chimiques et géophysiques en laboratoire a permis de mieux caractériser les processus de complexation étudiés et d’appuyer considérablement l’interprétation des signaux PPS. Enfin, la tomographie de résistivité électrique et la méthode de Mise-A-La-Masse ont été combinées pour développer une nouvelle approche d'imagerie du chemin préférentiel emprunté par le courant électrique dans le système racines-sols. Etant donné que la conduction électrique dans le sol et les racines est principalement électrolytique, l'approche proposée repose sur le mouvement de l'eau et des solutés dans le système racines-sol. Le potentiel de la méthode pour son application in-situ a été testée à l’aide d’une série d’expériences sur une vigne. À la suite des résultats prometteurs, la méthode a été développée et appliquée lors d’une expérience en laboratoire portant sur la croissance racinaire dans un rhizotron de plantes de coton et de maïs. La méthode s'est révélée sensible aux différences physiologiques entre les espèces et éventuellement à la réponse de la plante aux facteurs de stress environnementaux. De nouvelles expériences contrôlant les variables physiologiques des tissus racinaires sont nécessaires pour une meilleure compréhension de leurs influences. Les développements technologiques récents soutiennent fortement la diffusion de l’imagerie et du suivi géoélectriques à l'échelle du terrain. Dans ce contexte prometteur, les résultats de cette thèse contribuent au développement d'approches géoélectriques pour l'étude du sol et de ses interactions mutuelles avec les racines des plantes à des échelles spatio-temporelles pertinentes. / In this thesis I investigate some of the possibilities offered by the use of geoelectrical methods for characterizing soil geochemical processes and root-soil interactions. The motivation for this thesis arises from the pivotal role of soil quality and root-soil interactions in manifold environmental issues. In addition, there is growing evidence of the importance of mutual interactions between roots and soil, for this reason this thesis explores the use of geoelectrical methods for more comprehensive approaches. Both soil physicochemical processes and root-soil interactions involve, among others, the movement of water and solutes, altercations of the soil structure, and biological feedbacks. Geoelectrical methods are potentially sensitivity to these hydrogeological and biogeochemical modifications. The Spectral Induced Polarization (SIP) method was combined with geochemical analyses and modeling in order to investigate its sensitivity to pore fluid composition, pH, and ionic strength. In particular, the SIP signature of Na+/Cu2+ substitution was investigated because of their worldwide relevance for soil quality. The SIP investigation focused on saturated silica, and explored concentrations of Na+ and Cu2+ that are typical to agricultural soils exposed to the use of Cu pesticides. The results showed how pH and ionic strength were the main variables controlling the SIP signals, while negligible effects were related to the Cu/Na substitution. The concurrent use of chemical and geophysical laboratory experiments allowed a better characterization of the investigated complexation processes and significantly supported the interpretation of the SIP signals. The Electrical Resistivity Tomography and the Mise-A-La-Masse methods were combined to develop a novel approach for imaging the electric current pathways in the root-soil system. Since the current conduction in soil and roots is mostly electrolytic, the proposed approach relates to the movement of water and solutes within the root-soil system. The potential of the method for field investigations was explored with a set of experiments on a grapevine. In light of the promising results, the method was further developed and applied to rhizotron laboratory experiments on cotton and maize plants. The method proved to be sensitive to inter-species physiological differences and possibly to the plant response to environmental stressors. New experiments with physiological analyses of root tissues are needed to elucidate these aspects. Emerging technologies are strongly supporting to the diffusion of imaging and monitoring geoelectrical applications at the field-scale. In this promising context, the results of this thesis contribute to the development of geoelectrical approaches for studying soil and its mutual interactions with plant roots over relevant spatiotemporal scales.

Durant les dernières décennies, les composites polymères renforcés par des fibres végétales ont reçu une attention importante de la part des scientifiques. L’utilisation de fibres végétales permet en effet d’améliorer les performances environnementales de ces matériaux tout en atteignant des propriétés spécifiques plus élevées. Néanmoins, un verrou majeur freine encore le développement de ces matériaux. En effet, leur sensibilité au vieillissement hydrique, due à leur caractère hydrophile, restreint leur utilisation. Dans ce contexte, nous proposons, dans le cadre de cette thèse, d’analyser l’effet du vieillissement hydrique sur le comportement statique et dynamique, d’identifier et suivre les mécanismes d’endommagement d’une structure sandwiche biosourcée et ses constituants. Les composites utilisés sont constitués d'une résine greenpoxy associée à des fibres de lin et à une âme en liège pour les sandwichs. Dans la première partie, nous avons étudié le comportement en statique et en dynamique de la résine, du composite, des âmes et des sandwichs. Cette étude a conduit d’une part à la détermination des caractéristiques mécaniques et à l’identification et le suivi des mécanismes d’endommagement par émission acoustique et observations microscopiques et d’autre part à la détermination des caractéristiques dynamiques. Dans la deuxième partie, nous avons analysé la cinétique de diffusion d'eau dans la résine, les peaux, les âmes et les sandwichs par identification de leurs paramètres de diffusion par le modèle de Fick. En suite, nous sommes intéressés à l’impact du vieillissement hydrique sur le comportement et les propriétés mécaniques des sandwichs et ses constituants. / In recent decades, polymer composites reinforced with plant fibers have received significant attention from scientists. The use of reinforcing vegetable fibers makes it possible to improve the environmental performance of these materials reaching higher specific properties. Nevertheless, a major lock still hinders the development of these materials. Indeed, their sensitivity to water ageing, due to their hydrophilic nature, restricts their use. In this context, we propose, as part of this thesis, to analyze the effect of water ageing on static and dynamic behavior, to identify and monitoring the damage mechanisms of a sandwich structure biobased and its constituents. The composites used consist of a greenpoxy resin associated with flax fibers and a cork core for sandwich materials. In the first part of this work, we studied the static an dynamic behavior of the resin, the composites, cores and sandwich structures. This study led on the one hand to the determination of the mechanical characteristics and to the identification and the follow-up of the mechanisms of damage by acoustic emission and microscopic observations and on the other hand to the determination of the dynamic characteristics. In the second part, we first analyzed the kinetics of water diffusion in resin, skins, cores and sandwichs by identification of their diffusion parameters by the Fick model approach. Then, we are interested in the impact of water ageing on the behavior and mechanical properties iof sandwichs and its constituents.

Dans une stratégie de diversification des apports en acides gras polyinsaturés très longue chaîne n-3 (AGPI TLC n-3), essentiels à la santé de l'Homme et majoritairement apportés par les produits de la mer, l'objectif de la thèse était de mieux comprendre les mécanismes cellulaires pouvant expliquer la faible teneur en AGPI TLC n-3 présente dans le muscle de bovin, ceci en explorant trois voies métaboliques de ces acides gras potentiellement limitantes (biosynthèse, captage facilité et peroxydation non-enzymatique) par des approches de qPCR ou de transcriptomique. Les principaux résultats montrent que le foie et les muscles de bovin possèdent tout le matériel génétique nécessaire à la synthèse des AGPI TLC n-3 et pourraient donc assurer leur synthèse, sauf chez le mâle entier où l'expression du gène de l'élongase 5 est réprimée par la présence d'hormones sexuelles mâles. D'autre part, les teneurs musculaires en AGPI TLC n-3 plus élevées avec un régime base d'herbe par rapport à de l'ensilage de maïs et dans un muscle glycolitique par rapport à un muscle oxydatif ne semblent pas s'expliquer par une modulation de l'expression des gènes impliqués dans leur biosynthèse, ni dans leur captage facilité et dans la régulation endogène de leur lipoperoxydation. En conclusion, ce travail de thèse a permis de considérablement faire progresser la compréhension des mécanismes impliqués dans la régulation des dépôts d'AGPITLC n-3 dans les muscles de bovin. Toutefois, ces régulations sont certainement plus complexes et probablement multifactorielles. De nombreuses pistes restent encore à explorer avant d'envisager augmenter la teneur en AGPI TLC n-3 dans la viande bovine. / N-3 very long chain polyunsaturated fatty acids (n-3 VLC PUFA) are essential for human health but are almost exclusively present in seafood. Thus, in a strategy of diversification of n-3 VLC PUFA sources for human, the aim of this thesis was to better understand the cellular mechanisms that may explain the low n-3 VLC PUFA content in bovine muscle, by exploring three potentially limiting metabolic pathways of these fatty acids (biosynthesis, facilited uptake and non-enzymatic peroxidation) by qPCR or transcriptomic approaches. The main results indicate that the liver and muscles of cattle possess all the genetic material necessary for the synthesis of n-3 VLC PUFA and may therefore ensure their synthesis, except in entire males where gene expression of the elongase 5 is suppressed by the presence of male sex hormones. On the other hand, the higher n-3 VLC PUFA content in muscle of cattle with a grass based diet compard to corn silage and in glycolytic muscle compared to oxidative muscle do not seem to be explained by a modulation of gene expression of proteins involved in their biosynthesis or in their facilited uptake or in the endogenous regulation of their lipoperoxidation. In conclusion, this thesis has greatly advance our understanding of mechanisms involved in the regulation of n-3 VLC PUFA deposits in muscles of cattle. However, these regulations are certainly more complex and probably multifactorial. Many tracks remain to be explored before considering increasing n-3 VLC PUFA content in beef.

Phosphorus (P) is an essential plant nutrient that may limit plant growth and agricultural productivity if not available for crop plant uptake in sufficient quantities at the time required. Many Australian soils are deficient in available P, despite a long history of P fertilizer application, and this is due to fertilizer P rapidly becoming unavailable largely through biochemical fixation. The resulting low P fertilizer efficiency, coupled with rapidly rising cost of fertilizers, has increased interest in biological cycling of P from sources such as crop residues. However, to date, much of the Australian research has focussed on soils with relatively high organic matter content (> 2%) and relatively heavy texture i.e. medium to high clay content. Furthermore, although there is information on pasture residue decomposition and P release for sandy soils with low organic matter in Australia, a recent shift to continuous cropping systems means that information for a range of crop residues is required but is not currently available. Therefore the aims of the work described in this thesis were to (i) increase the efficiency of P use when crop residue P are applied to crops and (ii) determine the effect of crop residue biochemical quality on decomposition rates, soil P dynamics and plant P uptake in light textured sandy soils with low organic matter which are typical of a large proportion of the southern Australian wheat growing area. A further aim was to investigate the effects of combined additions of plant residue and P fertilizer on P cycling in these soils, a scenario highly relevant to farming systems. A series of soil incubation and plant growth experiments were undertaken to characterize P dynamics in soil following addition of a wide range of crop residues (total 15) collected from agricultural sites throughout South Australia. The residues, differing in age and biochemical quality, were young shoots of canola, lupin, pea, lucerne and lentil; mature shoot residues of canola, lupin, pea and wheat and mature root residues of wheat, canola and lupin. The concentration of total and water soluble P, C, and N in the residues was measured using standard wet chemical analyses and the carbon chemistry was determined by NMR spectroscopy. Decomposition of crop residues was continuously monitored over a period of up to 140 days by measuring soil respiration. Available P and microbial biomass P and C were also assessed at different times during the incubations. The total P in residues ranged from 0.16% to 0.32% and 0.05% to 0.08% in young and mature shoots, respectively. Water-soluble P was related to residue total P and ranged from 29% to 81% and 13% to 29% of total P in young and mature shoots, respectively. The C: P ratio ranged from 133: 1 to 253: 1 and 504: 1 to 858: 1 in young and mature shoots, respectively. Phosphorus availability and microbial P uptake differed between soils amended with crop residues and soluble P fertilizer as triple super phosphate (TSP). Soil respiration rates were significantly higher in soils amended with crop residues than in the soils amended with TSP or the unamended control in the first 58 days of incubation. In an experiment in which residues and TSP were added at a rate of 10 mg P kg⁻¹, available P was greater for TSP than residue-amended soil, whereas microbial P showed the opposite trend. Respiration rate and microbial P were positively correlated with C addition rate, which was highest in mature wheat residue because it had the lowest P concentration. In order to assess when P released from the residues is available for plants, wheat was grown over three consecutive crop periods with each period lasting for 4 weeks. Young residues with high content of water soluble P, C, N and amide and low lignin and phenolic content decomposed faster than mature residues. The C type and amount added with residues controlled the dynamics of P availability. Surprisingly, canola mature root increased available P and plant growth as much as young shoot residues while root residues of wheat and lupin resulted in P immobilization and low plant growth. Compared to canola young shoot, canola mature root has a higher total P concentration and a lower C: P ratio. Plant P uptake was positively correlated with residue total and water-soluble P content and negatively correlated with residue C: P and C: N ratio and amount of C added with the residues. In another experiment where residue was added at 2.5 g C kg⁻¹ soil and compared with TSP (4 and 10 mg P kg⁻¹ soil), available P and plant P uptake decreased in the following order: TSP-10P > canola root ≥ young shoot ≥ TSP-4P > control > mature shoot. Microbial P was greater with residue addition than with TSP and in the control. Residues with low total P and high C: P ratio resulted in P immobilisation in the microbial biomass. Therefore, residues with high total P and low C: P ratio can be an important source of P for plants. Net P immobilisation of mature wheat residues (0.07% P) was significantly reduced by combining wheat residue (C: P ratio 615: 1) with TSP leading to a C: P ratio of 155: 1 to 310: 1. Furthermore, the combination of wheat residue with TSP increased available P in residue and TSP-amended soils by 3.0 mg P kg⁻¹ soil, which was shown to be sufficient to support wheat growth in the early stages of development in the other experiments. Although water-soluble P fertilizers provide plants with immediately available P, a large proportion becomes unavailable over time. Addition of low C: P residues on the other hand, may not result in high amounts of immediately available P, but the P supply is more sustained due to P release from decomposing residues and turnover of microbial biomass P. Phosphorus immobilization after addition of residues which have high C: P ratio (615: 1) may be offset when residue is applied together with inorganic P fertilizer if the resulting C: P ratio is 300: 1 or less. Overall, this study has highlighted the potential role that crop residues, either alone or in combination with inorganic P, can play in increasing P availability in the light textured, low organic matter, P-limited soils typical of many southern Australian farming systems. The results provide important quantitative information on the potential of a wide range of crop residues to supply wheat with P, and how additions of inorganic P interact with residue decomposition and influence available P supply. This quantitative information will be valuable for the construction or validation of mechanistic models of residue decomposition relevant to low organc matter light textured soils in farming systems of southern Australia, and will ultimately assist in the development of economic management strategies for minimizing P fertilizer inputs and maximizing the benefits of biological cycling of P. / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

<p>Lichens are fascinating symbiotic systems, where a fungus and a unicellular alga, most often green (bipartite green algal lichens; 90% of all lichens), or a fi lamentous cyanobacterium (bipartite cyanobacterial lichens; 10% of all lichens) form a new entity (a thallus) appearing as a new and integrated organism: in about 500 lichens the fungus is associated with both a cyanobacterium and an alga (tripartite lichens). In the thallus, the lichen bionts function both as individual organisms, and as a symbiont partner. Hence, in lichens, the participating partners must both be able to receive and acquire resources from the other partner(s) in a controlled way.</p><p>Lichens are particularly successful in harsh terrestrial environments. In part this is related to their poikilohydric nature and subsequent ability to repeatedly become desiccated and hydrated. Metabolic activity, i.e. photosynthesis, respiration, and for cyanobacterial lichens N2-fixation, is limited to periods when the thallus is suffi ciently hydrated. Mineral nutrients are mainly acquired from dry or wet deposition directly on the thallus. Taken together it then appears that lichens are to a large extent passively controlled by their environment, making their control over resource allocation and acquisition particularly challenging.</p><p>The aim of this thesis was to investigate resource acquisition and allocation processes in different lichens, and to see how these respond to changes in resource availability. This was done by following lichen growth in the fi eld during manipulation of water, light, and nutrient supply, and by assessing the responses of both the integrated thallus as well as the individual bionts. As a fi rst step, resource allocation and acquisition was investigated for a broad range of lichens aiming to determine the magnitude of metabolic variation across lichens. Seventy-fi ve lichen species were selected to cover as broad a spectrum as possible regarding taxonomy, morphology, habitat, and nitrogen requirements. The lichens had invested their nitrogen resources so that photosynthetic capacity matched respiratory carbon demand around a similar equilibrium across the contrasting species. Regulation of lichen growth was investigated in another study, using the two tripartite species <i>Nephroma arcticum</i> and <i>Peltigera aphthosa</i>, emphasizing the contribution of both internal and external factors. The empirical growth models for the two lichens were similar, showing that weight gain is to a higher extent dependent on those external factors that regulate their photosynthesis, whilst area gain is more controlled by internal factors, such as their nitrogen metabolism. This might be inferred from another study of the same species, where nitrogen manipulations resulted in an undisturbed weight gain, a similar resource allocation pattern between the bionts, but a distorted area gain. </p><p>Aiming to investigate lichen nitrogen relations even further, lichens’ capacities to assimilate combined nitrogen in the form of ammonium, nitrate and amino acids were assessed using 14 contrasting boreal species. All these had the capacity to assimilate all the three nitrogen forms, with ammonium absorption being more passive, and nitrate uptake being low in bipartite cyanobacterial lichens. Differences in uptake capacities between species were more correlated to photobiont than to morphology or substrate preferences. Finally, to investigate intra-specifi c plasticity in relation to altered nutrient supply, resource investments between photo- and mycobiont were investigated in the two bipartite green algal lichens <i>Hypogymnia physodes </i>and and <i>Platismatia glauca</i> in a low and a high nutrient environ- in a low and a high nutrient environ- ment. In both species, more of the resources had been directed to the photobiont in the high nutrient environment also increasing their overall carbon status. Taken together, my studies indicate that in spite of the apparent passive environmental control on lichen metabolism, these symbiotic organisms are able to both optimize and control their resource acquisition and allocation processes.</p>

<p>Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance in a laboratory environment using classical and freestyle techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance coefficient, µ_R, in order to allow correct comparisons between the results, as well as providing the opportunity to study work economy between different athletes, test occasions and core techniques.</p><p>Thus, one of the aims of this thesis was to evaluate how roller skis’ µ_R is related to warm-up, mass, velocity and inclination of the treadmill. It was also necessary to investigate the methodological variability of the rolling resistance measurement system, RRMS, specially produced for the experiments, with a reproducibility study in order to indicate the validity and reliability of the results.</p><p>The aim was also to study physiological responses to different µ_R during roller skiing with freestyle and classical roller skis and techniques on the treadmill as a case in which all measurements were carried out in stationary and comparable conditions.</p><p>Finally, the aim was also to investigate the work economy of amateurs and female and male junior and senior cross-country skiers during treadmill roller skiing, i.e. as a function of skill, age and gender, including whether differences in body mass causes significant differences in external power per kg due to differences in the roller skis’ µ_R.</p><p>The experiments showed that during a warm-up period of 30 minutes, µ_R decreased to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively. For another 30 minutes of rolling no significant change was found. Simultaneous measurements of roller ski temperature and m_R showed that stabilized m_R corresponds to a certain running temperature for a given normal force on the roller ski. The study of the influence on m_R of normal force, velocity and inclination produced a significant influence of normal force on m_R, while different velocities and inclinations of the treadmill only resulted in small changes in m_R. The reproducibility study of the RRMS showed no significant differences between paired measurements with either classical or the freestyle roller skis.</p><p>The study of the effects on physiological variables of ~50% change in µ_R,showed that during submaximal steady state exercise, external power, oxygen uptake, heart rate and blood lactate were significantly changed, while there were non significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed and this occurred without a significantly changed maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion was non significant or small.</p><p>The final part of the thesis, which focused on work economy, found no significant difference between the four groups of elite competitors, i.e. between the two genders and between the junior and senior elite athletes. It was only the male amateurs who significantly differed among the five studied groups. The study also showed that the external power per kg was significantly different between the two genders due to differences in body mass and m_R, i.e. the lighter female testing groups were roller skiing with a relatively heavier rolling resistance coefficient compared to the heavier testing groups of male participants.</p> / Sporttech

<p>Drug transport across the intestinal epithelium is roughly predicted from permeability values obtained from Caco-2 cell monolayers. This thesis examines the important role of <i>pH</i> and extracellular additives for increasing the reliability and predictivity of the <i>in vitro</i> screening system, Caco-2.</p><p>It was shown that the passive transport of ionizable compounds may be biased by a false efflux or uptake component, when applying a physiological <i>pH</i>-gradient across the membrane. <i>pH</i> also affected the amount of compound available at the transporter-binding site. Therefore, <i>pH</i> dependence should be considered in studies of such compounds and of drug-drug interactions involving efflux transporters. It was also shown that proton-dependent apical uptake or basolateral efflux should be studied both with and without a <i>pH</i> gradient over the whole monolayers. </p><p>The two extracellular additives, bovine serum albumin (BSA) and the solubilizing agent, Cremophor^® EL, also influenced Caco-2 permeabilities. BSA applied to the receiver side increases, and to the donor side decreases drug permeation according to the drug’s protein binding capacity. Thus, the absorptive transport for both passive and active compounds is favoured, giving a physiologically sound improvement of the Caco-2 cell model. Inclusion of BSA increased both the predictivity and quality of permeability studies, particularly of highly lipophilic, BCS class II compounds. Passive and active transport processes could also be distinguished after accounting for unbound concentrations. The overall effect of Cremophor^® EL on the permeability to a drug was compound-specific and probably dependent on micellar incorporation. Cremophor^® EL can therefore not be recommended. </p><p>Neither <i>pH</i> nor BSA affect the functionality of transporters such as P-glycoprotein. However, efflux ratios of ionizable or protein bound drugs are altered in the presence of a <i>pH</i>-gradient or BSA, indicating that an experimental system without protein or <i>pH</i> gradient can over- or underestimate active and passive efflux in drug transport.</p>