L’objectif de cette thèse a été d’étudier, en présence d’un écoulement laminaire, la génération et la détection électrochimiques de gradients locaux de concentration à l’intérieur de canaux microfluidiques. L’influence des paramètres géométriques et hydrodynamiques sur les réponses ampérométriques de microélectrodes a été analysée théoriquement par simulation numérique. Pour cela, plusieurs approches ont été entreprises par le biais de modèles à deux et à trois dimensions afin de résoudre l’équation du transport pour différentes géométries de dispositifs et conditions d’écoulement. Des critères ont été fixés afin de délimiter les régimes et conditions optimales de fonctionnement. Les prévisions issues des calculs ont été testées puis validées à l’aide de mesures expérimentales effectuées à partir de microdispositifs fabriqués au laboratoire. Ainsi, deux concepts innovants ont été définis pour la mise en œuvre au sein de microdispositifs de fonctions combinant microfluidique et électrochimie. Le premier est celui d’une sonde de concentration à très haute résolution temporelle. Le second est la génération d’un gradient linéaire de concentration sur la section d’un canal microfluidique rectangulaire. / The aim of this thesis was to study the electrochemical generation and electrochemical detection of local concentration gradients within microfluidic channels in presence of a laminar flow. The influence of geometric and hydrodynamic parameters on the amperometric responses of microelectrodes was analyzed theoretically by means of numerical simulations. Several approaches were undertaken using two-dimensional and three-dimensional models in order to solve the transport equation according to the device geometries and flow conditions. Criteria were set to delineate the operating regimes and optimal conditions. Predictions from calculations were tested and validated experimentally using microdevices fabricated in the laboratory. Therefore, two innovative concepts were defined for the implementation of functions within microdevices combining microfluidics and electrochemistry. The first one is a probe of concentration leading to very high temporal resolution. The second one is the generation of a linear concentration gradient over the cross section of a rectangular microfluidic channel.

Abstract Recognition of the importance of a regional perspective for understanding the structure and dynamics of local assemblages has stimulated the emergence of the field of macroecology. Most attention has been directed to terrestrial ecosystems, while large-scale patterns in biodiversity of aquatic organisms have received less attention. In this thesis I examined patterns of aquatic diversity across several geographic areas and scales, in an effort to understand some of the environmental and spatial factors determining species diversity in aquatic environments. The main objectives of this thesis were: (i) to examine the latitudinal diversity patterns of marine crustaceans and molluscs and their relationship to large scale environmental gradients, (ii) to study macroinvertebrate species richness in headwater streams at two spatial extents, within and across drainage systems, and assess the relative importance of local, landscape and regional variables, and (iii) to study diversity patterns of macroorganisms vs microorganism, comparing distance decay patterns of stream diatoms, macroinvertebrates and bryophytes. Latitudinal diversity patterns of crustaceans and molluscs were clearly related to larval developmental mode. An increase in species richness towards high latitudes was found for species with direct development, whereas richness of species with planktotrophic development decreased poleward. Sea surface temperature was the most important environmental gradient related to species richness of both phyla and each developmental mode, but with different effects on each mode. Stream macroinvertebrate species richness at the bioregion extent was negatively related to water humic content. Another factor related to species richness at the bioregion extent was elevation range, a variable linked to stream topographic heterogeneity. Local environmental variables explained most of the variation in species richness at the drainage system extent, however high among-region variability was evident. Patterns between macro- and microorganism may not be fundamentally different, but the level of environmental control varied, being strongest for diatoms, while some groups of benthic macroinvertebrates exhibited relatively strong dispersal limitation. The relative importance of niche vs. dispersal processes is not simply a function of organism size but other traits (e.g. life-history type, dispersal capacity) may obscure this relationship.

Urban runoff is a non-point pollution source deteriorating water quality of natural watersystems. The composition of urban runoff vary depending on land use, seasonal changes anddifferent surfaces that come into contact with the water. Urban runoff often contain metals andAl, Cd, Cr, Cu, Fe, Ni, Pb and Zn are of particular concern for the environment due to theirpotential toxicity. Metals in runoff can be present in different phases, associated with particles,colloids of different sizes or dissolved in the free phase. The different phases vary in size butalso overlap each other. Information about metal phases and species in runoff is essential tounderstanding metal transport and design runoff treatment systems.Membrane filtration followed by ultrafiltration is an established technique to distinguish theparticulate, colloidal and truly dissolved fractions. However, the “truly dissolved” fraction mayconstitute of the free phase, colloidal phase or both of them since the technique onlydiscriminates by size. Diffusive gradients in thin films (DGT) is a relatively new technique thatmeasures the labile fraction, sometimes referred to as the most bioavailable fraction. The labilefraction includes free metal ions and small complexes available to diffuse through a diffusivelayer under a reasonable period of time. Kinetically inert species are discriminated.The scope of this thesis was to investigate metal fractionation in snowmelt runoff from differenturban surfaces using two techniques, ultrafiltration and DGT. An additional aim was to studythe speciation described by the two techniques in the different types of runoff. Two types ofrunoff were sampled to conduct measurements on. Runoff from well-defined catchments (anindustrial area and a parking lot) and roof runoff from two roofing materials (zinc and coppersheet). In total, four runoff samples were membrane filtrated (pore size 0.45 μm) followed byeither ultrafiltration (delimiting 3 kNMWL) or DGT measurements in the laboratory. Analysisof metals was conducted in all steps and pH, electric conductivity, total suspended solids andtotal organic carbon was measured in the untreated samples.The results show that metal concentrations were generally higher in the catchment runoffcompared to the roof runoff with few exceptions, Cu and Pb from copper roof and Zn from zincroof. Regarding fractionation, the two types of runoff showed similarities when it came tometals mainly bound to particles. The metals that were abundant in several phases showeddifferent fractionations between the catchment runoff and the roof runoff. The metals releasedin roof runoff was to a higher extent found as free ions compared with the catchment runoff. Adiscussion was held about the different metal fractions and treatment possibilities. Comparingthe two techniques, the DGT measurements could be used to further interpret the results fromthe ultrafiltration regarding the colloidal and free phase. / Dagvatten är en diffus föroreningskälla som försämrar vattenkvalitén hos naturliga vattendrag.Samansättningen av föroreningar i dagvatten kan variera beroende på markanvändning,årstidsvariationer och de olika ytor som dagvattnet kommer i kontakt med. Dagvatten innehållerofta metaller och Al, Cd, Cr, Cu, Fe, Ni, Pb och Zn kan vara toxiska för miljön i högakoncentrationer. Metaller i dagvatten kan förekomma i olika faser beroende på om de är bundnamed partiklar, kolloider av olika storlek eller om de är i löst fas. De olika faserna varierar istorlek men överlappar även varandra något. Kunskap om de olika faserna är viktigt förförståelsen om metallernas transportmekanismer och för att kunna designa eller förbättrareningssystem.Membranfiltrering följt av ultrafiltrering är en etablerad teknik för att särskilja partikulärtmaterial, kolloider och den sanna lösta fraktionen. Dock så kan den ”sanna lösta” fraktioneninnehålla antingen den kolloidala fasen, lösta fasen eller båda två eftersom tekniken baseras påstorleksfördelning. DGT (på engelska diffusive gradients in thin films) är en relativt ny tekniksom mäter den labila fraktionen som ibland benämns som den mest biotillgängliga fraktionen.Den labila fraktionen inkluderar fria metalljoner men även små komplex som kan diffunderagenom en diffusionsgel under en rimlig tidsperiod. Species som är kinetisk inerta kommer intemätas.Syftet med detta arbete var att undersöka metallfraktionering i snösmälts-avrinning från olikaurbana ytor genom att använda två tekniker, ultrafiltrering och DGT. Ett delmål var även attgranska de species som beskrevs av de två teknikerna i de olika typerna av dagvatten. Två olikaslags dagvatten samlades in och undersöktes. Dagvatten från väldefinierade avrinningsområden(ett industriområde och en parkeringsplats) och takavrinning från två takmaterial (zink- ochkopparplåtar). Totalt fyra dagvattenprover genomgick membranfiltrering (porstorlek 0,45 μm)följt av antingen ultrafiltrering (avgränsning 3 kNMWL) eller DGT mätningar i laboratoriet.Metallanalyser genomfördes i alla steg och pH, konduktivitet, suspenderade partiklar ochorganiskt kol mättes på det obehandlade proverna.Resultaten visade att de uppmätta metallkoncentrationerna var generellt högre i takavrinningenjämfört med dagvattnet från de hela avrinningsområdena. Dock med några undantag, Cu ochPb från koppartak och Zn från zinktak. När det kom till fraktionering fanns det likheter mellanavrinning från hela områden och från taken beträffande de metaller som till största del varbundna till partiklar. Däremot var det skillnad mellan de olika avrinningstyperna gällandefraktionering av metallerna som förekom i flera av faserna. I takavrinningen fanns det i störreutsträckning metaller som fria joner jämfört med avrinningsområdena. En slutsats var att DGTmätningarna kunde användas till att tolka resultaten från ultrafiltreringen när det gälldekolloidala och fria faserna.

Studies assessing the evolution of plant traits frequently focus on pollinators as the primary drivers of floral trait evolution. However, herbivores can also play a role, and, under some circumstances, may even impose stronger selection on floral display than pollinators. This is especially true when the traits under selection are linked to anti-herbivore defense. Here I describe a study in which I quantified the relative role of herbivores and pollinators in selection for floral traits in the North American invasive plant, purple loosestrife (Lythrum salicaria). Because L. salicaria responds to leaf-chewing herbivores by producing compensatory tissue growth, and this in turn alters the architecture of the floral display, I further tested whether herbivores can indirectly modify pollinator-mediated selection through this pathway. Using a split-plot design, I measured pollen limitation and reproductive output in experimentally manipulated plants in the presence and absence of simulated herbivore damage in order to quantify the effects of damage and pollination on natural selection for floral display. My results showed that damage significantly increased direct selection (beta-i) for earlier flowering time and decreased selection on the number of inflorescences, even more than pollinators did. Because damage did not modify pollinator-mediated selection for floral display traits, the selection imposed by herbivores is likely only having direct effects. My findings demonstrate the importance of considering multiple agents of selection and their potential interactions when quantifying natural selection in a study system. In particular, it is important to consider that the agent most frequently studied may not be imposing the brunt of selection.

The Broad Caribbean region is defined as the Gulf of Mexico, and the coastal and marine areas of the Caribbean Sea, including the chain of islands forming the Greater and Lesser Antilles, Turks and Caicos, the Bahamas, and the gulf coasts of the United States, Central and South America (Stanley, 1995). The cephalopods of the Broad Caribbean were examined in terms of distribution, abundance, and ecological importance. A suite of 5190 preserved cephalopod specimens were identified and catalogued to produce regional maps of cephalopod distribution within the Broad Caribbean. Eighteen range extensions were noted for known species. Regional species richness was examined with respect to Rapoport's Rule with an eye toward possible cephalopod hotspots in the region. Cephalopods of the Broad Caribbean within the latitudinal bands of 8°N and 30°N do not support Rapoport's Rule as they exhibit increasing species richness with increasing latitude. Eight subareas were chosen to compare species richness. Regionally, species richness is patchy, with the largest concentration of cephalopods off the eastern Florida coast. Areas of the southern Caribbean Sea are in need of more samples for accurate assemblage counts and more meaningful comparisons with other Caribbean regions. Rarefaction curves were used to normalize the variously sized samples throughout the Broad Caribbean. A checklist of the Gulf of Mexico based on literature developed a picture for the northern regions of the Broad Caribbean. This checklist provided an updated account of cephalopod species that were reported from smaller literature works. Lastly, the first observation in the North Atlantic Ocean of the deep-sea squid Asperoteuthis acanthoderma (family Chiroteuthidae) was described. The description is based on two nearly intact, but damaged, specimens that were found floating at the surface in the waters off Key West and Marathon, Florida in 2007. All previously known records are recorded from a few specimens scattered in the western Pacific Ocean. There is a need for increased sampling throughout the Broad Caribbean to explore the systematics, life histories, distribution patterns, and potential fisheries for this group of organisms.

Performance of automatic speech recognition (ASR) systems utilizing only acoustic information degrades significantly in noisy environments such as a car cabins. Incorporating audio and visual information together can improve performance in these situations. This work proposes a lip detection and tracking algorithm to serve as a visual front end to an audio-visual automatic speech recognition (AVASR) system. Several color spaces are examined that are effective for segmenting lips from skin pixels. These color components and several features are used to characterize lips and to train cascaded lip detectors. Pre- and post-processing techniques are employed to maximize detector accuracy. The trained lip detector is incorporated into an adaptive mean-shift tracking algorithm for tracking lips in a car cabin environment. The resulting detector achieves 96.8% accuracy, and the tracker is shown to recover and adapt in scenarios where mean-shift alone fails.

This master's thesis prepared the programme which is able to follow the trajectories of the movement of people and based on this to create various statistics. In practice it is an effective marketing tool which can be used for instance for customer flow analyses, optimal evaluation of opening hours, visitor traffic analyses and for a lot of other benefits. Histograms of oriented gradients, SVM classificator and optical flow monitoring were used to solve this problem. The method of multiple hypothesis tracking was selected for the association data. The system's quality was evaluated from the video footage of the street with the large concentration of pedestrians and from the school's camera system, where the movement in the corridor was monitored and the number of people counted.

Within a lifetime of an individual, there are changes in the organism leading to an an impairment of phenotype, survival and reproduction. The expression of phenotypic traits often increases with age. Higher expression of these traits in the young age can lead to decreased probability of survival till the next season, influencing reproductive success of an individual. That is why organisms are challenged with trade-offs, when they have to allocate their limited resources either into the reproduction in form of expression of extravagant sex ornaments or into the life span. If the ornament evolved as a handicap, its exaggerated size could reduce viability of low quality individuals. Therefore, the ornament becomes a predictor of quality of its bearer and its size indicates the ability to survive till the next season. Both sexual ornamentation and inter-individual variation in life span may result in differences in reproductive success (fitness) and targeted by sexual or natural selection. Variability in reproductive success, mainly in monogamous species, can be increased also by sexual promiscuity and extra-pair mating and extra-pair copulations. This strategy can increase the opportunity for selection of traits that play role in choosing of extra-pair mate. In this work, I focused on two potential...

Cell fate decisions in many physiological processes, including embryogenesis, stem cell niche homeostasis and wound healing, are regulated by secretion of small signaling proteins, called cytokines, from source cells to their neighbors or into the environment. Concentration level and steepness of the resulting paracrine gradients elicit different cell responses, including proliferation, differentiation or chemotaxis. For an in-depth analysis of underlying mechanisms, in vitro models are required to mimic in vivo cytokine gradients. We set up a microparticle-based system to establish short-range cytokine gradients in a threedimensional extracellular matrix context. To provide native binding sites for cytokines, agarose microparticles were functionalized with different glycosaminoglycans (GAG). After protein was loaded onto microparticles, its slow release was quantified by confocal microscopy and fluorescence correlation spectroscopy. Besides the model protein lysozyme, SDF-1 was used as a relevant chemokine for hematopoietic stem and progenitor cell (HSPC) chemotaxis. For both proteins we found gradients ranging up to 50 µm from the microparticle surface and concentrations in the order of nM to pM in dependence on loading concentration and affinity modulation by the GAG functionalization. Directed chemotactic migration of cells from a hematopoietic cell line (FDCPmix) and primary murine HSPC (Sca-1+ CD150+ CD48-) toward the SDF-1-laden microparticles proved functional short-range gradients in a twodimensional and three-dimensional setting over time periods of many hours. The approach has the potential to be applied to other cytokines mimicking paracrine cell-cell interactions in vitro

Background: Coastal ecosystems in Mexico remain understudied in spite of their ecological, economic and conservation value and are being impacted by human activities along the coast. Knowledge on spatial patterns of plant species distribution that helps preserve these fragile ecosystems is crucial. Aims: We evaluated differences in species richness, species diversity and species dominance patterns in 16 plant communities as well as the degree to which differences were driven by climatic conditions in sandy dunes in Yucatán. We evaluated the importance of invasive species in mediating patterns of species diversity and species dominance patterns. Results: We found wide variation in plant species richness, species diversity and species dominance patterns among communities that stems from broad climatic differences along dune systems. Invasive plants represent almost one-third of total species richness and seem to be drastically changing the species dominance patterns in these communities. Conclusions: Regional climatic differences along the Yucatán north coast seems to be a major driver of plant diversity and species composition. Our findings suggest that invasive plants have successfully colonised and spread along the coast over the past 30 years. Even though invasive species do not alter spatial patterns of species diversity, they are becoming more dominant with potential detrimental consequences for native plants.