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Zhang, Ying. "Dynamic spatio-temporal interaction of morphogens, forces and growth in embryonic morphogenesis." [Bloomington, Ind.] : Indiana University, 2007. 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:3297105.
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Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2007.<br>Title from dissertation home page (viewed Sept. 29, 2008). Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0881. Adviser: James A. Glazier.
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Pradhananga, Nipesh. "Construction site safety analysis for human-equipment interaction using spatio-temporal data." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52326.
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The construction industry has consistently suffered the highest number of fatalities among all human involved industries over the years. Safety managers struggle to prevent injuries and fatalities by monitoring at-risk behavior exhibited by workers and equipment operators. Current methods of identifying and reporting potential hazards on site involve periodic manual inspection, which depends upon personal judgment, is prone to human error, and consumes enormous time and resources. This research presents a framework for automatic identification and analysis of potential hazards by analyzing spatio-temporal data from construction resources. The scope of the research is limited to human-equipment interactions in outdoor construction sites involving ground workers and heavy equipment. A grid-based mapping technique is developed to quantify and visualize potentially hazardous regions caused by resource interactions on a construction site. The framework is also implemented to identify resources that are exposed to potential risk based on their interaction with other resources. Cases of proximity and blind spots are considered in order to create a weight-based scoring approach for mapping hazards on site. The framework is extended to perform ``what-if'' safety analysis for operation planning by iterating through multiple resource configurations. The feasibility of using both real and simulated data is explored. A sophisticated data management and operation analysis platform and a cell-based simulation engine are developed to support the process. This framework can be utilized to improve on-site safety awareness, revise construction site layout plans, and evaluate the need for warning or training workers and equipment operators. It can also be used as an education and training tool to assist safety managers in making better, more effective, and safer decisions.
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Koger, Jace. "Spatio-temporal History of Fluid-rock Interaction in the Hurricane Fault Zone." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5911.
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The Hurricane Fault is a 250-km long, west dipping, Basin and Range-bounding normal fault in SW Utah and NW Arizona that initiated in the mid-Miocene to Pliocene. It has been primarily active in the Quaternary, with slip rates of 0.2 – 0.6 mm/yr. There are multiple hot springs along its 250-km length and multiple late Tertiary-Quaternary basaltic centers broadly parallel the fault. Possible sources of hot spring fluids include deeply-circulated meteoric water that experienced water-rock exchange at high temperatures (>100 °C) and deep-seated crustal fluids. Aside from the source of modern hot spring fluids and heat, questions about the spatio-temporal history of fluid flow along the Hurricane Fault remain unaddressed. Abundant damage zone veins, cements, and host rock alteration are present, indicative of past fluid flow. Carbonate veining and cementation is a key feature of the Hurricane Fault zone, and is the primary feature exploited to characterize the thermochemical history of fault-related paleofluids. A combination of macroscopic and microscopic carbonate observations, chemical composition, and precipitation temperature of calcite veins was used to determine past water-rock diagenetic interaction and vein evolution in the Hurricane Fault zone. Calcite iv in concretions and veins from the damage zone of the fault shows a wide range of carbon and oxygen stable isotope ratios, with δ13CPDB from -4.5 to 3.8 ‰ and δ18OPDB from -17.7 to -1.1‰. Fluid inclusion microthermometry homogenization temperatures range from 45 to 160 °C, with fluid salinities of 0 to 15 wt% NaCl calculated from melting temperatures. Combining the two datasets, two main fluids that interacted with the fault zone are inferred: (1) basin brines with a δ 18OSMOW of 9.2 ‰ and (2) altered meteoric fluids with a δ 18OSMOW of -11.9 to -8.3 ‰. Calculated dissolved CO2 δ 13CPDB (-8.5 to -1.3 ‰) indicates mixed marine carbonate and organic or magmatic sources. Fault zone diagenesis was caused by meteoric water infiltration and interaction with carbonate-rich rocks, mixed with upwelling basin brines. Fluid-rock interaction is concentrated in the damage zone, where fracture-related permeability was utilized for fluid flow. A distinct mineralization event punctuated this history, associated with basin brines that were chemically influenced by nearby basaltic magmatism. This implies a hydrologic connection between the fault and regional magmatism.
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Nesrallah, Michael J. "Spatio-Temporal Theory of Optical Kerr Nonlinear Instability." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34313.
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This work derives a nonlinear optical spatio-temporal instability. It is a perturbative analysis that begins from Maxwell’s equations and its constituent relations to derive a vectorial nonlinear wave equation. In fact, it is a new theoretical method that has been developed that builds on previous aspects of nonlinear optics in a more general way. The perturbation in the wave equation derived is coupled with its complex conjugate which has been taken for granted so far. Once decoupled it gives rise to a second-order equation and thus a true instability regime because the wavevector can become complex. The solution obtained for the perturbation that co-propagates with the driving laser is a generalization to modulation and filamentation instability, extending beyond the nonlinear Schrodinger and nonlinear transverse diffusion equations[1][2]. As a result of this new mechanism, new phenomena can be explored. For example, the Kerr Nonlinear Instability can lead to exponential growth, and hence amplification. This can occur even at wavelengths that are typically hard to operate at, such as into far infrared wave- lengths. This provides a mechanism for obtaining amplification in the far infrared from a small seed pulse without the need for population inversion. The analysis provides the basic framework that can be extended to many different avenues. This will be the subject of future work, as outlined in the conclusion of this thesis.
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Osorio, Cañadas Sergio. "Spatio-temporal variability of bee/wasp communities and their host-parasitoid interaction networks." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/457746.
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Uno de los principales objetivos de la ecología es comprender cómo la biodiversidad está estructurada espacial y temporalmente, y cuáles son los mecanismos subyacentes a los gradientes de biodiversidad en diferentes escalas espaciales y temporales. En esta tesis, analizo la variabilidad espacio-temporal de comunidades de abejas/avispas (huéspedes) y de sus parasitoides, y de las redes de interacción huésped-parasitoide que se establecen entre ellas. Las especies de abejas y avispas muestran notables diferencias temporales en su fenología, y, por otro lado, las especies de abejas muestran diferentes capacidades termorreguladoras en relación con su tamaño corporal (cuanto más grandes es una, mayor es su capacidad termoreguladora). Por tanto, se podría hipotetizar una relación entre el tamaño corporal (~’grado de endotermia’) y la temperatura ambiente durante el período de vuelo del adulto. Las comunidades de abejas y avispas también muestran una considerable heterogeneidad espacial en respuesta a sus recursos alimentarios y de nidificación. Estos cambios espacio-temporales en las comunidades de abejas/avispas podrían conllevar cambios en sus ‘rasgos funcionales’, y podrían tener un impacto en sus comunidades de parasitoides y, en consecuencia, esto podría reflejarse en cambios en la estructura de sus redes de interacción y en las funciones ecosistémicas asociadas.
En el capítulo 1 se analizó la relación entre el tamaño corporal y la temperatura a lo largo de un gradiente de temperatura ambiental intra-anual, utilizando una fauna regional de abejas mediterráneas. Esperábamos encontrar especies más grandes (más endotérmicas) en las estaciones más frías, y especies progresivamente más pequeñas hacia estaciones más cálidas. Esto se puede considerar un test a la ‘norma de Bergmann’ a lo largo de un gradiente de temperatura temporal (en lugar de su formulación clásica a lo largo de gradientes geográficos). Encontramos una relación diferente entre el tamaño corporal y la temperatura ambiente de las especies para las abejas grandes ('endotérmicas') y para las pequeñas (ectotérmicas): las especies mayores que 27,81 mg (peso seco) siguieron la norma de Bergmann, mientras que las especies por debajo de este umbral no mostraban ningún patrón. Nuestros resultados extienden la norma de Bergmann a un gradiente temporal y son coherentes con el mecanismo fisiológico propuesto originalmente por el propio Bergmann ("hipótesis termorreguladora").
Para estudiar las redes de interacción huésped-parasitode se utilizaron comunidades de abejas y avispas nidificantes en cavidades preestablecidas (AANCP), que actúan como 'huéspedes', y sus comunidades de parasitoides, en una zona templada (Capítulos 2 y 3).
En el capítulo 2 se estudiaron los efectos de la estacionalidad (primavera vs verano) sobre la estructura y composición taxonómica y funcional de las comunidades de AANCP y de sus parasitoides, y sobre sus redes de interacción. Se encontraron notables cambios estacionales en la estructura taxonómica y funcional, y en la composición tanto de la comunidad de AANCP como de parasitoides. Sin embargo, no encontramos cambios estacionales en el porcentaje de parasitismo, y los pocos cambios estacionales en la estructura de la red de interacción parecían principalmente motivados por cambios en el tamaño de la red.
Por último, en el capítulo 3 se estudiaron los efectos de los factores espaciales locales (ambiente de nidificación: granjas vs agrupaciones de árboles) y paisajísticos (gradiente de cobertura agrícola) sobre la estructura taxonómica y la composición de las comunidades de AANCP y de sus parasitoides, y sobre sus redes de interacción. La estructura y composición de la comunidad AANCP, así como la estructura de la red, fueron mucho más dependientes de los factores locales que de los factores del paisaje. Los hábitats abiertos asociados con explotaciones extensivas favorecen la diversidad local de AANCP (especialmente abejas) lo que origina redes de interacción huésped-parasitoide más complejas en comparación con áreas boscosas.<br>One of the main goals in ecology is to understand how biodiversity is spatial and temporally structured, and which are the mechanisms underlying biodiversity gradients at different spatial and temporal scales. In this thesis, I analyze spatial and temporal variability in bee/wasp (hosts) and their parasitoid communities, and in the antagonistic interaction networks between them. Bees, wasps and their parasitoids are related to key ecosystem functions (e.g., pollination or herbivore populations control). Bee and wasp species show notably seasonal differences in their phenology. Bee species also show different thermoregulatory capabilities in relation with their body size (the bigger the bee species, the more ‘endothermic’ the species are). So, it could be hypothesized a relationship between body size (~endothermic capabilities) and ambient temperature in the period of adult flying activity. Bee and wasp communities also have been shown to be spatially heterogeneous in response to food and nesting resources. Temporal and spatial changes in bee/wasp communities are expected to impact in their parasitoid communities, as they depend on their host communities. Moreover, if host and parasitoid community structure and composition change over space and time, their functional traits, interaction patterns, network structure and ecosystem functionality are also expected to change spatio-temporally.
In Chapter 1 we tested the body size-temperature relationship along an intra-annual, seasonal environmental temperature gradient using a Mediterranean regional bee fauna. We expected to find larger bee species (i.e. more endothermic species) in colder seasons, and progressively smaller bee species towards warmer seasons. This approaches to the Bergmann’s rule along a temporal temperature gradient (instead of their classical formulation along geographical gradients). We found a different relationship between body size and ambient temperature for large (‘endothermic’) and small (ectothermic) bee species: species larger than 27.81 mg (dry weight) followed Bergmann’s rule, whereas species below this threshold did not (no relationship at all). Our results extend Bergmann’s rule to a temporal gradient and are coherent with the physiological mechanism proposed originally by Bergmann himself (“thermoregulatory hypothesis”).
In order to analyze spatial and temporal variability in antagonistic interaction networks, we used cavity-nesting bees and wasp communities (‘CNBW’, acting as ‘hosts’), and their interacting ‘parasitoid’ communities in a temperate zone (Chapters 2 and 3).
In Chapter 2, we studied the effects of seasonality (spring vs. summer) on taxonomic and functional structure and composition of CNBW and their parasitoid communities, and on their interaction networks. We found strong seasonal changes in taxonomic and functional structure and composition of both the CNBW host and their parasitoid communities. However, we did not find seasonal shifts in percent parasitism, and the few seasonal changes in the structure of the host-parasitoid interaction network appeared to be mostly driven by changes in network size. Our results underscore the need to consider functional traits and to incorporate a temporal component into network analysis if we are to understand the global relationship between network structure and ecosystem function.
Finally, in Chapter 3 we studied the effects of local (nesting environment: farms vs tree stands) and landscape (forest-cropland gradient) spatial factors on taxonomic structure and composition of CNBW hos and their parasitoid communities, and on their interaction networks. CNBW host community structure and composition, as well as network structure, were much more dependent on local than on landscape factors. Open habitats associated with extensively farmed exploitations favor local CNBW diversity (especially bees) and result in more complex host–parasitoid interaction networks in comparison to forested areas. This study highlights the conservation value of this kind of open habitat in view of the progressive abandonment of extensively cultivated farmland in favor of agricultural intensification and reforestation taking place in Europe.
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Vallot, Dorothée. "Modelling calving and sliding of Svalbard outlet glaciers : Spatio-temporal changes and interactions." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-334787.
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Future sea level rise associated to global warming is one of the greatest societal and environmental challenges of tomorrow. A large part of the contribution comes from glaciers and ice sheets discharging ice and meltwater into the ocean and the recent worldwide increase is worrying. Future predictions of sea level rise try to encompass the complex processes of ice dynamics through glacier modelling but there are still large uncertainties due to the lack of observations or too coarse parameterisation, particularly for processes occurring at the glacier interfaces with the bed (sliding) and with the ocean (calving). This thesis focuses on modelling these processes from two marine-terminating glaciers in Svalbard, Kronebreen and Tunabreen. By inverting three years of high temporal resolution time-series of surface velocities on Kronebreen, basal properties are retrieved with the ice flow model Elmer/Ice in Paper I. Results suggest that surface melt during the summer greatly influences the dynamics of the following season and that sliding laws for such glaciers should be adapted to local and global processes changing in space and time. The subglacial drainage system, fed by the surface melt, is modelled in Paper II during two melting seasons. Results show different configurations of efficient and inefficient drainage systems between years and the importance of using a sliding law dependent on spatio-temporal changes in effective pressure. The interaction with the ocean is incorporated in Paper III by combining a series of models, including an ice flow model, a plume model and a particle model for discrete calving and compares the output with observations. Results show the importance of glacier geometry, sliding and undercutting on calving rate and location. However, more observations and analytic methods are needed. Time-lapse imagery placed in front of Tunabreen have been deployed and a method of automatic detection for iceberg calving is presented in Paper IV. Results show the influence of the rising plume in calving and the front destabilisation of the local neighbourhood.
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Jian, Jinshi. "Global soil respiration: interaction with macroscale environmental variables and response to climate change." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/92195.
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The response of global soil respiration (Rs) to climate change determines how long the land can continue acting as a carbon sink in the future. This dissertation research identifies how temporal and spatial variation in environmental factors affects global scale Rs modeling and predictions of future Rs under global warming. Chapter 1 describes the recommend time range for measuring Rs across differing climates, biomes, and seasons and found that the best time for measuring the daily mean Rs is 10:00 am in almost all climates and biomes. Chapter 2 describes commonly used surrogates in Rs modeling and shows that air temperature and soil temperature are highly correlated and that they explain similar amounts of Rs variation; however, average monthly precipitation between 1961 and 2014, rather than monthly precipitation for a specific year, is a better predictor in global Rs modeling. Chapter 3 quantifies the uncertainty generated by four different assumptions of global Rs models. Results demonstrate that the time-scale of the data, among other sources, creates a substantial difference in global estimates, where the estimate of global annual Rs based on monthly Rs data (70.85 to 80.99 Pg C yr-1) is substantially lower than the current benchmark for land models (98 Pg C yr-1). Chapter 4 simulates future global Rs rates based on two temperature scenarios and demonstrates that temperature sensitivity of Rs will decline in warm climates where the level of global warming will reach 3°C by 2100 relative to current air temperature; however, these regional decelerations will be offset by large Rs accelerations in the boreal and polar regions. Chapter 5 compares CO2 fluxes from turfgrass and wooded areas of five parks in Blacksburg, VA and tests the ability of the Denitrification-Decomposition model to estimate soil temperature, moisture and CO2 flux across the seasons.
Cumulatively, this work provides new insights into the current and future spatial and temporal heterogeneity of Rs and its relationship with environmental factors, as well as key insights in upscaling methodology that will help to constrain global Rs estimates and predict how global Rs will respond to global warming in the future.<br>Ph. D.
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Tran, Van Canh [Verfasser], and Michael [Akademischer Betreuer] Gertz. "Learning Social Links and Communities from Interaction, Topical, and Spatio-Temporal Information / Canh Tran Van ; Betreuer: Michael Gertz." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1180032055/34.
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Roussel, Éléonore. "Spatio-temporal dynamics of relativistic electron bunches during the microbunching instability : study of the Synchrotron SOLEIL and UVSOR storage rings." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10067/document.
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Les paquets d'électrons relativistes circulant dans les anneaux de stockage sont des sources de rayonnement VUV, X et THz incontournables. Cependant, ces systèmes sont également connus pour présenter des instabilités dynamiques. Dans cette thèse, nous nous sommes intéressés à l'instabilité dite de microbunching, qui mène à l'apparition de microstructures à l'échelle millimétrique, et à l'émission de bouffées intense de rayonnement THz cohérent. L'objectif de la thèse était d'avancer dans la compréhension de la dynamique non-linéaire de ces structures, en combinant études expérimentales et numériques. Les expériences ont été effectuées au Synchrotron SOLEIL et à UVSOR, et les études numériques ont été principalement basées sur l'équation de Vlasov-Fokker-Planck. Dans un premier temps, la rapidité des échelles de temps impliquées nous a menés à réaliser des études indirectes. Des informations sur la dynamique à l'échelle picoseconde ont ainsi pu être déduites d'enregistrements au moyen de détecteurs possédant des constantes de temps beaucoup plus lentes (la microseconde), et en particulier en étudiant la réponse à des perturbations laser. Ensuite, au moyen de deux techniques nouvelles, nous avons pu réaliser les premières observations directes des structures et de leur dynamique. A UVSOR, nous avons utilisé un détecteur THz à film mince de YBCO supraconducteur. Ensuite, nous avons développé une méthode originale associant l'effet électro-optique et l'étirement temporel, ce qui nous a permis d'atteindre une résolution picoseconde, au Synchrotron SOLEIL. Ces nouvelles observations nous ont immédiatement permis de réaliser des tests extrêmement sévères des modèles théoriques<br>Relativistic electron bunches circulating in storage rings are used to produce intense radiation from far-infrared to X-rays. However, above a density threshold value, the interaction between the electron bunch and its own radiation can lead to a spatio-temporal instability called microbunching instability. This instability is characterized by a strong emission of coherent THz radiation (typically 105 times stronger than the classical synchrotron radiation) which is a signature of the presence of microstructures (at mm scale) in the electron bunch. This instability is known to be a fundamental limitation of the operation of synchrotron light sources at high beam current. In this thesis, we have focused on this instability from a nonlinear dynamics point of view by combining experimental studies carried out at the Synchrotron SOLEIL and UVSOR storage rings with numerical studies mainly based on the Vlasov-Fokker-Planck equation. In a first step, due to the very indirect nature of the experimental observations, we have sought to deduce information on the microstructure wavenumber either by looking at the temporal evolution of the THz signal emitted during the instability or by studying the response of the electron bunch to a laser perturbation. In a second step, we have achieved direct, real time observations of the microstructures dynamics through two new, very different, detection techniques: a thin-film superconductor-based detector at UVSOR, and a spectrally-encoded electro-optic detection technique at SOLEIL. These new available experimental observations have allowed severe comparisons with the theoretical models
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Roussel, Eléonore. "Spatio-temporal dynamics of relativistic electron bunches during the microbunching instability : study of the Synchrotron SOLEIL and UVSOR storage rings." Electronic Thesis or Diss., Lille 1, 2014. http://www.theses.fr/2014LIL10067.
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Les paquets d'électrons relativistes circulant dans les anneaux de stockage sont des sources de rayonnement VUV, X et THz incontournables. Cependant, ces systèmes sont également connus pour présenter des instabilités dynamiques. Dans cette thèse, nous nous sommes intéressés à l'instabilité dite de microbunching, qui mène à l'apparition de microstructures à l'échelle millimétrique, et à l'émission de bouffées intense de rayonnement THz cohérent. L'objectif de la thèse était d'avancer dans la compréhension de la dynamique non-linéaire de ces structures, en combinant études expérimentales et numériques. Les expériences ont été effectuées au Synchrotron SOLEIL et à UVSOR, et les études numériques ont été principalement basées sur l'équation de Vlasov-Fokker-Planck. Dans un premier temps, la rapidité des échelles de temps impliquées nous a menés à réaliser des études indirectes. Des informations sur la dynamique à l'échelle picoseconde ont ainsi pu être déduites d'enregistrements au moyen de détecteurs possédant des constantes de temps beaucoup plus lentes (la microseconde), et en particulier en étudiant la réponse à des perturbations laser. Ensuite, au moyen de deux techniques nouvelles, nous avons pu réaliser les premières observations directes des structures et de leur dynamique. A UVSOR, nous avons utilisé un détecteur THz à film mince de YBCO supraconducteur. Ensuite, nous avons développé une méthode originale associant l'effet électro-optique et l'étirement temporel, ce qui nous a permis d'atteindre une résolution picoseconde, au Synchrotron SOLEIL. Ces nouvelles observations nous ont immédiatement permis de réaliser des tests extrêmement sévères des modèles théoriques<br>Relativistic electron bunches circulating in storage rings are used to produce intense radiation from far-infrared to X-rays. However, above a density threshold value, the interaction between the electron bunch and its own radiation can lead to a spatio-temporal instability called microbunching instability. This instability is characterized by a strong emission of coherent THz radiation (typically 105 times stronger than the classical synchrotron radiation) which is a signature of the presence of microstructures (at mm scale) in the electron bunch. This instability is known to be a fundamental limitation of the operation of synchrotron light sources at high beam current. In this thesis, we have focused on this instability from a nonlinear dynamics point of view by combining experimental studies carried out at the Synchrotron SOLEIL and UVSOR storage rings with numerical studies mainly based on the Vlasov-Fokker-Planck equation. In a first step, due to the very indirect nature of the experimental observations, we have sought to deduce information on the microstructure wavenumber either by looking at the temporal evolution of the THz signal emitted during the instability or by studying the response of the electron bunch to a laser perturbation. In a second step, we have achieved direct, real time observations of the microstructures dynamics through two new, very different, detection techniques: a thin-film superconductor-based detector at UVSOR, and a spectrally-encoded electro-optic detection technique at SOLEIL. These new available experimental observations have allowed severe comparisons with the theoretical models
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Timme, Sandra [Verfasser], Marc Thilo Günter [Gutachter] Figge, Oliver [Gutachter] Kurzai, and Lars [Gutachter] Kaderali. "Agent-based modelling of the spatio-temporal interaction between immune cells and human-pathogenic fungi / Sandra Timme ; Gutachter: Marc Thilo Günter Figge, Oliver Kurzai, Lars Kaderali." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/120588551X/34.
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Kabacinski, Adeline. "Physique et application d'une source cohérente femtoseconde à 32.8 nm par interaction laser-plasma." Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAE018.
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Les lasers XUV collisionnels en régime d’ionisation par le champ sont obtenus en focalisant une impulsion laser pompe infrarouge ultra-intense dans une cible gazeuse, ce qui génère une colonne de plasma en situation d'inversion de population. Dans cette thèse, on s’intéresse à l’émission de la transition 3d^{9}4d -> 3d^{9}4p du krypton IX nickelloïde à 32,8 nm. L’injection de ce plasma amplificateur par une source harmonique externe améliore considérablement les propriétés spatiales du rayonnement tout en tirant profit des qualités énergétiques de l’amplificateur.Grâce à l'implémentation d'un canal plasma permettant le guidage de l'impulsion pompe, de récentes recherches ont permis de travailler à des densités électroniques proches de 10^20 cm^-3. Ces conditions sont extrêmement favorables puisque les plus fréquentes collisions électrons-ions favorisent l'inversion de population, ce qui mène à des gains accrus. Dans le même temps, ces collisions provoquent une surionisation de l'ion lasant et donc une interruption anticipée du gain. Des simulations ont montré que cette diminution conséquente de la durée de vie du gain se répercutait sur la durée d'impulsion à 32,8 nm. Dans le cadre de cette thèse, le développement d'un diagnostic mono-tir de mesure du profil temporel de l'impulsion a permis de démontrer expérimentalement ce résultat : limitées à la picoseconde à basses densités, des durées de 520 fs RMS, en accord avec des simulations Maxwell-Bloch, ont ainsi pu être mesurées à 8x10^19 cm^-3.Cette thèse a également permis de dépasser une autre limite : la dispersion naturelle du plasma qui provoque intrinsèquement une désynchronisation entre l'harmonique XUV injectée et la zone de gain. La compensation de ce phénomène, indispensable à haute densité, a été réalisée grâce à l'introduction de couplages spatio-temporels dans le faisceau pompe et a permis une amélioration significative des performances de la source avec notamment une meilleure extraction de l'énergie. Il a également été démontré que la durée d'impulsion pouvait être maintenue constante au cours de la propagation à des valeurs aussi faibles que 350 fs RMS.L'ensemble de ce travail offre des perspectives pour bon nombre d'applications, telle que la génération de seconde harmonique dans l'XUV également explorée dans ce manuscrit<br>Collisionally-pumped plasma-based soft X-ray lasers in optical field ionization regime are obtained by focusing an ultra-intense infrared laser pump pulse into a gas target. The interaction generates a plasma column in population inversion. In this thesis, we are interested in the 3d^{9}4d -> 3d^{9}4p transition of nickel-like krypton ion at 32,8 nm. The seeding of this amplifying medium by an external harmonic source considerably improves the spatial properties of the radiation while taking advantage of the energetic qualities of the amplifier.Thanks to the implementation of a plasma channel to guide the pump beam, recent research has made it possible to operate at electron densities close to 10^20 cm^-3. These conditions are extremely beneficial since the more frequent collisions favor population inversion and lead to increased gains. At the same time, these collisions cause an overionization of the lasing ion and thus an early interruption of the gain. Simulations have shown a consequent decrease of the soft X-ray laser pulse duration at high densities. Within the framework of this thesis, the development of a single-shot diagnostic to measure the temporal profile of the pulse allowed to demonstrate this result experimentally : limited to the picosecond at low densities, durations of 520 fs RMS, in agreement with Maxwell-Bloch simulations, have been measured at 8x10^19 cm^-3.This thesis also enabled to overcome the natural dispersion of the plasma which intrinsically causes a desynchronization between the harmonics and the gain region. The compensation of plasma dispersion, essential at high densities, has been achieved by harnessing spatio-temporal couplings and has allowed a significant improvement of the source performance with notably a better energy extraction. It was also demonstrated that the pulse duration could be kept constant along propagation at values as low as 350 fs RMS.All these improvements offer perspectives for many applications such as second harmonic generation in the soft X-rays, also explored in this manuscript
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Nicvert, Lisa. "Méthodes statistiques et outils logiciels pour l'analyse et l'inférence de réseaux écologiques et le traitement de données multi-espèces." Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10130.
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Les interactions entre espèces dans les communautés écologiques sont complexes : de nombreuses espèces peuvent interagir les unes avec les autres de façons variées et à différentes échelles spatiales et temporelles. De plus, ces réseaux d'interactions sont la résultante de multiples causes, engendrent de multiples processus et ont des conséquences parfois indirectes transmises au travers de la structure du réseau. Cette complexité nécessite une diversité d'approches pour comprendre les déterminants des interactions et prédire leurs effets dans les systèmes écologiques. Cette thèse étudie plusieurs aspects des réseaux d'interactions écologiques par une approche méthodologique qui se concentre sur la description, l'évaluation et le développement de méthodes statistiques et d'outils logiciels. Dans une première partie, j'étudie les causes de la structure des réseaux d'interactions en me concentrant sur les niches d'interactions et en utilisant la notion de concordance des traits entre espèces. Pour cela, j'utilise des méthodes de la famille de l'analyse des correspondances et j'applique et j'étends des méthodes de mise à l'échelle réciproque à l'analyse de réseaux bipartites. J'applique ces méthodes à l'analyse d'un réseau d'interactions plantes-frugivores d'une forêt de montagne péruvienne et je montre que les traits des espèces peuvent être reliés à leur largeur de niche. Dans une deuxième partie, j'étudie les conséquences des interactions au travers de leur influence sur la répartition spatio-temporelle des espèces. Pour cela, j'utilise des processus de Hawkes multivariés pour analyser des données de pièges photographiques. J'illustre ces modèles sur cinq mammifères de la savane sud-africaine et je montre des attractions et évitements entre plusieurs de ces espèces à courte échelle spatio-temporelle. Dans une troisième partie, je me penche sur l'analyse de données collectées par pièges photographiques. Je développe un package R pour nettoyer et standardiser ces données à l'usage du programme Snapshot Safari, ainsi qu'une application Shiny destinée à un usage plus général pour visualiser de données de façon interactive et reproductible. Cette thèse présente des méthodes statistiques et outils logiciels pour analyser des données écologiques complexes et améliorer la compréhension des réseaux d'interactions. Ces résultats ouvrent des perspectives nouvelles concernant l'analyse de données écologiques ainsi que les développement méthodologique en écologie<br>Interactions between species in ecological communities are complex: many species can interact with each other in a variety of ways and at different spatial and temporal scales. Moreover, these interaction networks are the result of multiple causes, generate multiple processes and can have indirect effects transmitted through the structure of the network. This complexity calls for a variety of approaches to understand the determinants of interactions and predict their effects in ecological systems. This thesis studies several aspects of ecological interaction networks using a methodological approach that focuses on the description, evaluation and development of statistical methods and software tools. In a first part, I study causes of the structure of interaction networks, focusing on interaction niches and using the notion of trait matching between species. To this end, I use methods from the correspondence analysis family and apply and extend reciprocal scaling methods to the analysis of bipartite networks. I apply these methods to the analysis of a plant-frugivore interaction network in a Peruvian montane forest, and show that species traits can be related to their niche width. In a second part, I study the consequences of interactions through their influence on the spatio-temporal distribution of species. To this end, I use multivariate Hawkes processes to analyze camera trap data. I illustrate these models on five mammals from the South African savanna, showing attraction and avoidance between several of these species at a short spatio-temporal scale. In a third part, I consider camera trap data analysis. I develop a R package to clean and standardize camera trap data intended for the Snapshot Safari program, as well as a Shiny application intended for a more general use to visualize data in an interactive and reproducible way. This thesis presents statistical methods and software tools to analyze complex ecological data and improve our understanding of interaction networks. These results open new perspectives on ecological data analysis and methodological development in ecology
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Kong, Heng. "Variations spatio-temporelles de la structure taxonomique et la compétition alimentaire des poissons du lac Tonlé Sap, Cambodge." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30122/document.
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Le lac de Tonlé Sap (TSL), Cambodge, est un écosystème lac-rivière de forêt alluviale au régime d'écoulement alternatif. Le lac est un déversoir lors de l'inondation saisonnière du Mékong et sert de réservoir en période de basses eaux. La superficie du lac pendant la saison sèche (février à mai), est d'environ 2 700 km2 pour une profondeur d'environ 1 mètre. Cette superficie est pratiquement multipliée par six quand arrive la saison des pluies, pour atteindre près de 16 000 km2 et une profondeur de 9 mètres, noyant rizières et forêts. C'est le plus grand lac d'eau douce d'Asie du Sud-Est. C'est aussi l'une des zones de pêche d'eau douce les plus importantes et productives du monde avec près de 75% du volume annuel de pêche en eau douce du Cambodge, ce qui permet la survie de près de 2,5 millions de personnes. Les changements saisonniers du cycle hydrologique ont une influence sur la structuration des communautés de poissons à l'échelle temporelle et spatiale, mais aussi sur les comportements trophiques des principales espèces qui n'exploitent alors pas les mêmes habitats. Toutefois, le bassin versant du Mékong est en changement constant avec un développement important des infrastructures en lien avec l'eau : production d'hydro-électricité, besoins important en irrigation, maitrise des inondations, eau potable, ... Les changements climatiques accélèrent les modifications du cycle hydrologique annuel. Il est alors supposé que ces modifications ont des effets forts sur les habitats et les proies disponibles et finalement sur la biodiversité, notamment de l'ichtyofaune et sur l'abondance des poissons disponibles pour les pêcheries.Dans un premier temps, nous avons caractérisé les variations spatio-temporelles de la composition taxonomique des poissons et mis en lumière quels sont les déterminants de ces variations. À cette fin, nous avons estimé la diversité bêta comme la variance totale de la matrice site par communauté d'espèce et l'avons divisée en contribution locale à la diversité bêta (LCBD) et contribution des espèces à la diversité bêta (SCBD). Nous avons ensuite effectué plusieurs régressions linéaires pour déterminer si la richesse taxonomique, l'abondance des espèces et le niveau de l'eau expliquaient la variation temporelle de la contribution du site et de l'espèce à la diversité bêta. Nos résultats indiquent une forte variation temporelle de la diversité bêta due aux contributions différentielles des sites et des espèces à la variation spatiale de la composition taxonomique des poissons. Nous avons également constaté que la direction, la forme et l'effet relatif de la richesse spécifique, de l'abondance et du niveau de l'eau sur la variation temporelle des valeurs LCBD et SCBD varient grandement selon les sites. Ces résultats suggèrent ainsi une variation spatiale des processus conduisant à une variation temporelle de la composition de la communauté. Dans l'ensemble, nos résultats suggèrent que la composition taxonomique des poissons n'est pas distribuée de manière homogène dans l'espace et dans le temps et risque d'être affectée à l'avenir si la dynamique saisonnière d'écoulement du système est altérée par les activités humaines et/ou les changements climatiques. Dans un second temps, nous avons cherché à étudier le modèle d'évolution temporel des principales espèces en terme d'occurrence et d'abondance à travers le cycle saisonnier hydrologique<br>The Tonle Sap Lake (TSL), Cambodia, is a flood-pulse system. It is the largest natural lake in South- East Asia and constitutes one of the largest fisheries over the world, supporting the livelihood 2.5 million peoples. Seasonal change in annual hydrological cycle appears to have influence on fish community structure, both spatial and temporal variation, particularly on feeding behavior of TSL's fishes. Nonetheless, the Mekong River Basin is changing rapidly due to accelerating water infrastructure development (hydropower, irrigation, flood control, and water supply) and climate change, bringing considerable modifications to the annual flood-pulse of the TSL. Such modifications are expected to have strong impacts on fish biodiversity, abundance, reduced habitat and food availability within the lake. To invest how TSL's fish community structure responds to the seasonal change, how they shift their diet across hydrological cycles and feeding competing for food resource: First, we aim to characterize the spatio-temporal variations of fish taxonomic composition and to highlights the underlying determinants of these variations. For this purpose, we estimated beta diversity as the total variance of the site-by-species community matrix and partitioned it into Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD). We then performed multiple linear regressions to determine whether species richness, species abundances and water level explained the temporal variation in the contribution of site and species to beta diversity. Our results indicate strong temporal variation of beta diversity due to differential contributions of sites and species to the spatial variation of fish taxonomic composition. We further found that the direction, the shape and the relative effect of species richness, abundances and water level on temporal variation in LCBD and SCBD values greatly varied among sites, thus suggesting spatial variation in the processes leading to temporal variation in community composition. Overall, our results suggest that fish taxonomic composition is not homogeneously distributed over space and time and is likely to be impacted in the future if the flood-pulse dynamic of the system is altered by human activities. Second, we aim to investigate the temporal pattern of the most occurrence and abundance species and how their co-occurrence pattern across hydrological cycles. We found that occurrence and abundance patterns were temporally varied at all water level seasons. Strong temporal variation in species occurrence was occurred with visiting species such as Labiobarbus leptocheilus and Poropuntius deauratus while water level starts to fill into the TSL. We further observed that the abundance of 17 species was strongly varied while other 22 species (mainly TSL's residential species) were stable within the year. Positive species co-occurrence pattern was generally higher than negative species co-occurrence at all water level seasons. Highest positive co-occurrence patterns were found during the period of decrease and low water level seasons while fishes are migrating from flooded areas, competing for resource and habitats during low water season. Study on temporal distribution and species co-occurrence of fish and how community responds to the seasonal change in hydrological cycles provides critical information for fisheries management and conservation in the Tonle Sap Lake (TSL) as well as maintaining fish biodiversity in the Mekong system. Third, the implications of seasonality on food web structure have been notoriously understudied in empirical ecology, particularly in TSL's system. The current study, we focus on seasonal changes in one key attribute of a food web, vertical trophic position of consumers
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Anandanadesan, Ananthi. "Modelling the spatio-temporal dynamics of aphid-parasitoid interactions." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/b6ace29c-4d4b-4e66-acd7-3f8a39c0656c.
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Simac, Alain. "Modélisation et gestion de concepts, en particulier temporels, pour l'assistance à la caractérisation de séquences d'images." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00614010.
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Les techniques habituelles d'indexation de vidéos passent généralement par une phase d'apprentissage qui nécessite préalablement la constitution d'une base d'apprentissage. Même si la taille de cette base est souvent réduite, la phase d'annotation réalisée par un expert de l'application est souvent longue et fastidieuse. Dans le cadre de cette thèse, nous avons développé un dispositif qui permet de pré-sélectionner un ensemble de prototypes susceptibles de contenir le concept qui doit apparaître dans la base d'apprentissage. Cette base réduite de prototypes sera ensuite annotée par l'expert. Nous nous sommes intéressés à des concepts temporels, ce qui nous a amené à étudier particulièrement des caractéristiques liées au mouvement, comme les points d'intérêt spatio-temporels (STIP Spatial Temporal Interest Points). D'autres caractéristiques ont aussi été utilisées concernant la couleur et la présence de formes particulières. Ces caractéristiques sont ensuite exploitées pour structurer la base de vidéos en briques spatio-temporelles homogènes. Cette structuration correspond à une sorte de segmentation de la base en fonction de chacune des caractéristiques. La liaison entre le concept à définir et les briques extraites de la base est en lien avec le fossé sémantique bien connu dans la problématique d'indexation automatique. La création de ce lien nécessite l'utilisation de la connaissance de l'expert de l'application sur le concept. Nous avons développé un système dans lequel cette connaissance est extraite par un système de questions/réponses. Les couples de questions/réponses permettent de sélectionner des briques répondant à la contrainte, de définir des relations entre certaines briques, et en- fin de naviguer dans l'arborescence des questions. Des tests ont été réalisés sur des bases de vidéos de provenances diverses telles que des vidéos provenant d'émissions de télévision, de films d'animation, ou encore des vidéos de laboratoire disponibles sur le net, ou réalisées par nos soins. Ces tests montrent les performances satisfaisantes mais aussi les limites de l'approche et ouvrent des perspectives intéressantes, particulièrement sur les aspects collaboratifs et les aspects adaptatifs qui permettraient de capitaliser les connaissances des experts applicatifs et rendraient le système plus efficient.
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Coughlan, Matthew Anthony. "Controlling Light-Matter Interactions and Spatio-Temporal Properties of Ultrashort Laser Pulses." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/186215.
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Chemistry<br>Ph.D.<br>The SPECIFIC method a fast and accurate method for generating shaped femtosecond laser pulses. The femtosecond pulses are user specified from pulse parameters in the temporal domain. The measured spectral and recovered temporal phase and amplitudes from SEA TADPOLE are compared with the theoretical pulse profile from the user specified input. The SPECIFIC method has been shown to be a technique that can generate a diverse array of spectral/temporal phase and amplitude as well as polarization pulse shapes for numerous scientific applications. The spatio -temporal -spectral properties of focusing femtosecond laser pulses are studied for several pulse shapes that are important for non-linear spectroscopic studies. We have shown with scanning SEA TADPOLE that the spatio-spectral phase of focusing double pulse profile changes across the laterally across the beam profile. The spectral features of the sinusoidal spectral phase shaped pulse has been shown to tilt at with a changing angle away from the focus of the lens. Using spatio-spectral coupling, we have shown that multiple spatio-temporal foci can be generated along and perpendicular to the focusing direction of a femtosecond laser pulse. The spatial position of the spatio-temporal foci is controlled optically. Using sinusoidal spectral phase modulated pulse trains fragment ion production from Benzonitrile parent molecule can be controlled. A spectral transmission window perturbed the temporal pulse amplitudes resulting in fragment ion production dependant on spectral window position. The spectral window ion production was shown to also be dependant on temporal phase sequence.<br>Temple University--Theses
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Smith, Maia A. "E-scape : interactive visualization of single cell phylogenetics and spatio-temporal evolution in cancer." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59018.
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Cancers evolve over time and space, producing a dynamic, heterogeneous mixture of related cells. Reconstructing the evolution of each cancer requires sequencing tumour cells and processing resulting data with novel computational and statistical methods. These advances have led to numerous insights, both clinical and biological, but the ability for a biologist to interact with these results across an experimental workflow remains limited, with expert intuition often injected only through cumbersome iterations of data analysis. Here we describe E-scape, a visualization tool suite enabling interactive analysis of cancer heterogeneity and evolution. The suite includes three tools: TimeScape and MapScape for visualizing population dynamics over time and space, respectively, and CellScape for visualizing evolution at single cell resolution. The tools integrate phylogenetic, clonal prevalence, mutation and imaging data to generate intuitive views of a cancer's evolution.<br>Science, Faculty of<br>Graduate
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Greenville, Aaron C. "The role of ecological interactions: how intrinsic and extrinsic factors shape the spatio-temporal dynamics of populations." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/13561.
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How individuals respond to environmental demands and pressures from conspecifics and from other species determines whether they will survive and reproduce, and hence whether their populations will persist. However, not all environments are benign or predictable, and not all populations of the same species respond to environmental pressures in the same way. The overall objective of this thesis was to incorporate both biotic and abiotic interactions into one conceptual framework to better understand and predict how species’ populations change across space and time. To help progress this objective, I built a trophic interaction model to capture the complexity of biotic and abiotic interactions in a model arid system, using long-term (over 20 years) ecological data on small vertebrates, climate and vegetation replicated across a large spatial area (8000 km2). The model was built upon smaller components that investigated the spatial and temporal dynamics of species’ populations and their biotic and abiotic drivers. A key achievement of this thesis is that it clarifies and confirms the importance of both biotic and abiotic interactions in arid resource-pulse environments. The trophic interaction model advances our knowledge on how interactions are context-specific and can change over space and time. It incorporates both bottom-up and top-down processes, and shows how the relative strength of these processes can change. I show also that simultaneous analysis of abiotic factors is important in predicting changes in species’ populations, and that biotic interactions (e.g. predation) can limit increases in consumer populations. In order to make accurate predictions about how species and ecological processes will respond to environmental change in arid systems, both biotic and abiotic factors need to be incorporated explicitly into models.
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Mahieux, Pierre. "Interactions tangibles pour naviguer spatialement et temporellement en environnements virtuels. : application à la médiation culturelle en histoire des sciences et techniques." Thesis, École nationale d'ingénieurs de Brest, 2022. https://nuxeo.enib.fr/nuxeo/nxpath/default/default-domain/workspaces/D%C3%A9p%C3%B4t%20des%20th%C3%A8ses@view_documents?tabIds=%3A&old_conversationId=0NXMAIN1.
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Les institutions de médiation culturelle, notamment les musées, utilisent de plus en plus les nouvelles technologies afin d'attirer les visiteurs. D'un côté, la Réalité Mixte permet aux visiteurs d'explorer des reconstitutions de lieux passés ou inaccessibles, mais aussi de naviguer spatialement et temporellement dans ces reconstitutions. D'un autre côté, les interfaces tangibles sont utilisées pour proposer des expériences interactives innovantes et engageantes.Dans cette thèse nous émettons l'hypothèse que l'utilisation d'interfaces tangibles faciliterait la navigation spatio-temporelle sur plusieurs échelles au sein d'Environnements Virtuels. Nos travaux ont deux objectifs : 1) proposer un modèle permettant de représenter l'espace et le temps sur plusieurs échelles ; 2) proposer une interface tangible permettant de naviguer sur ces différentes échelles.En réponse au premier objectif, notre proposition de représentation du temps et de l'espace s'appuie sur des notions utilisées en Histoire des Sciences & Techniques et propose quatre échelles. Nous nous appuyons sur notre modèle pour répondre au second objectif pour lequel nous avons mis en place une démarche de co-conception impliquant des experts en médiation culturelle. Le résultat de cette démarche est SABLIER, un interacteur tangible permettant de naviguer spatio-temporellement au sein d'un Environnement Virtuel<br>Cultural mediation institutions, especially museums, are increasingly using new technologies to attract visitors. On the one hand, Mixed Reality allows visitors to explore reconstructions of past or inaccessible places, but also to navigate spatially and temporally in these reconstructions. On the other hand, tangible interfaces are used to provide innovative and engaging interactive experiences.In this thesis we hypothesize that the use of tangible interfaces would facilitate spatio-temporal navigation on several scales within Virtual Environments. Our work has two objectives: 1) to propose a model to represent space and time on several scales; 2) to propose a tangible interface to navigate on these different scales.In response to the first objective, our proposition to represent time and space is based on notions used in the History of Science and Technology and proposes four layers. We rely on our model to respond to the second objective, for which we have set up a co-design process involving cultural mediation experts. The result of this approach is SABLIER, a tangible interactor allowing to navigate spatially and temporally within a Virtual Environment
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Rai, kurlethimar Yashas. "Visual attention for quality prediction at fine spatio-temporal scales : from perceptual weighting towards visual disruption modeling." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4027/document.
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Cette thèse revisite les relations entre les processus attentionnels visuels et la perception de qualité. Nous nous intéressons à la perception de dégradation dans des séquences d’images et leur impact sur la perception de qualité. Plutôt qu’un approcha globale, nous travaillons à une échelle spatio temporelle fine, plus adaptée aux décisions des encodeurs vidéo. Deux approches liant attention visuelle et qualité perçue sont explorées. La première, suit une approche classique, de type pondération des distorsions. Ceci est mis en relation avec des scénarios d’usage comme le streaming interactif ou la visualisation de contenus omnidirectionnels. Une seconde approche nous amène à introduire le concept de disruption visuelle (DV) et sa relation avec la perception de qualité. Nous proposons d’abord des techniques permettant d’étudier les saccades résultantes de la DV à partir par de données expérimentales oculométriques. Nous proposons ensuite un modèle computationnel de prédiction de la DV. Une nouvelle mesure objective de qualité est ainsi introduite nommée "Disruption Metric" permettant l’évaluation de la qualité locale de vidéos. Les résultats obtenus trouvent leurs applications dans de nombreux domaines tels que l’évaluation de qualité, la compression, la transmission perpétuellement optimisée de contenus visuel ou le rendu/visualisation foéval<br>This thesis revisits the relationship between visual attentional processes and the perception of quality. We mainly focus on the perception of degradation in video sequences and their overall impact on our perception of quality. Rather than a global approach, we work in a very localized spatio-temporal scale, more adapted to the decision-process in video encoders. Two approaches linking visual attention and perceived quality are explored in the thesis. The first follows a classical approach, of the distortion weighting type. This is very useful in certain scenarios such as interactive streaming or visualization of omni-directional content. The second approach leads us to the introduction of the concept of visual disruption(DV), and explore its relation to perceived quality. We first propose techniques for studying the saccades related to DV from experimental oculometric data. Then, a computational model for the prediction of DV is proposed. A new objective measurement of quality is therefore born, which we call the "Disruption Metric" : that allows the evaluation of the local quality of videos. The results obtained, find their applications in many fields such as quality evaluation, compression, perpetually optimized transmission of visual content or foveated rendering / transmission
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Gronnier, Julien. "Function of Plant Plasma Membrane Nanodomains : Study of Group 1 REMORINs during Plant-Virus Interactions." Electronic Thesis or Diss., Bordeaux, 2016. http://www.theses.fr/2016BORD0327.
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L’organisation par compartimentalisation est une propriété générale des systèmes naturels coordonnant les évènements biologiques dans l’espace et le temps. Au cours des trente dernières années, il a pu être démontré qu’à l’échelle d’une membrane de nombreux sous-compartiments coexistent. Une telle organisation semble cruciale pour l’ensemble des activités biologiques cellulaires et par conséquent prépondérante pour le développement et la survie des organismes vivants. La membrane plasmique présente une grande diversité de compartiments, néanmoins leurs fonctions et les mécanismes moléculaires régissant leur organisation ne sont pas très bien compris. Afin d’apporter de nouvelles informations sur comment et pourquoi la membrane plasmique des plantes est souscompartimentée, nous étudions les nanodomaines des REMORINEs du groupe 1 au cours de l’infection de N. benthamiana par le Potato Virus X (PVX). En menant une approche multidisciplinaire, nous avons décortiqué un mécanisme moléculaire impliqué dans l’organisation en nanodomaine de REMORIN à la membrane plasmique. Via la génération de mutants nous présentons des liens fonctionnels entre l’organisation en domaine de REMORIN, son statut de phosphorylation, sa capacité à réguler la perméabilité des plasmodesmes et la propagation de cellule à cellule du PVX. Nous présentons également des éléments montrant qu’au cours de la perception de PVX par N. benthamiana, l’organisation de la membrane plasmique est cruciale pour la mise en place des mécanismes de défense de la plante. Cette étude met en avant pour la première fois chez les plantes l’importance de la régulation spatio-temporelle des protéines à la membrane plasmique dans l’identité et la fonction de domaines membranaires<br>Organization by compartmentalization is a general property of natural systems coordinating biological events in space and time. Over the past three decades, it has been demonstrated that multiple micrometric to nano-metric sub-compartments co-exist at a single membrane level. Such membrane organization seems critical for most all cell bioactivities and therefore critical for development and survival of potentially all living organisms. Plants respond to pathogens by activating highly regulated plasma membrane-bound signalling pathways. Plant plasma membrane (PM) displays a great diversity of compartments, but underlying functions and molecular mechanisms governing such organization are not well understood. To get insight in how and why plant PM is compartmentalized, we choose to study the plant PM nanodomain goup 1 REMORIN during the interaction between N. benthamiana and the Potato Virus X (PVX). Using a multidisciplinary approach we decipher a molecular mechanism involved in defining REMORIN PM domains localization. Making mutants we provide a functional link between REMORIN PM organization at single molecule level, its phosphostatus, regulation of plasmodesmata permeability and PVX cell-to-cell movement restriction. We then provide evidences that during N.benthamiana PVX sensing, PM organization appears critical for the modulation plant defence mechanisms and cell signaling. This study provides a unique mechanistic insight into how tight control of protein spatio-temporal organization at PM level is crucial to confer membrane domains identity and functionality
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Galvan, Boris [Verfasser]. "Modeling the spatio-temporal evolution of fracture networks and fluid-rock interactions in GPU : Applications to lithospheric geodynamics / Boris Galvan." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1044870109/34.
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Cenier, Tristan. "Interactions entre rythmes rapides et rythmes lents dans la représentation de l’information olfactive dans le réseau bulbaire." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10093/document.
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Une particularité de la modalité sensorielle olfactive est la nature complexe du stimulus chimique à représenter. Les cellules sensorielles de la cavité nasale sont sensibles aux traits physico-chimiques des molécules et transmettent cette information vers le bulbe olfactif, premier relais central de cette modalité. L’organisation des voies de projection vers le bulbe entraîne une spatialisation de l’activité dans cette structure, ce qui constitue un mode de représentation de l’information mais qui n’est pas suffisant à lui seul. Le bulbe olfactif est également marqué par des phénomènes dynamiques prépondérants. Tout d’abord le rythme respiratoire, qui organise temporellement le niveau d’activation de l’appareil sensoriel, ensuite les oscillations des potentiels de champs locaux, et enfin les oscillations sous-liminaires des potentiels de membrane des cellules. Ces éléments dynamiques pourraient être le support de la formation d’assemblées de neurones, sous-populations de cellules synchronisées transitoirement et permettant la représentation de l’information suivant un principe spatio-temporel. Les travaux présentés dans cette thèse sont basés sur l’enregistrement conjoint des activités unitaires des cellules du bulbe, des oscillations des potentiels de champs locaux et de la respiration en réponse à des stimulations olfactives. Nous montrons les relations existant entre les différents phénomènes dynamiques et comment ils permettent d’organiser l’activité des cellules pour aboutir à la formation d’assemblées de neurones fonctionnelles. Nous mettons particulièrement en évidence le rôle central de la respiration dans le fonctionnement intégré du bulbe olfactif<br>A striking feature of the olfactory sensory system is its ability to deal with a complex multi-dimensional chemical stimuli. Receptor cells in the nasal cavity are sensitive to specific features of molecules and transmit this information to the olfactory bulb, first relay for olfaction in the central nervous system. Due to the organization of projection pathways to the bulb, afferent information activates the structure in a topographical fashion ; although this may constitute a coding strategy for olfactory information it has proven insufficient, and other strategies must be investigated. Dynamic phenomenons are a preponderant feature of the olfactory bulb. The respiratory rhythm imposes a sinusoidal level of activation to the system, oscillations in local field potentials and subthreshold oscillations in neurons membrane potentials may interact and lead to the transient synchronization of sub-populations of neurons. This particular mechanism, designated as neural assemblies, is in theory a good candidate for the representation of olfactory information. The work presented here is based on conjoint recordings, in anesthetized animals, of unitary activities, oscillations in the LFP and respiration, in response to olfactory stimulation. We show the relationships existing between the various dynamic phenomenons, and hypothesize on their functional roles. We propose that a same mechanism may form different neural assemblies each assuming a specific functional role. The respiratory rhythm acts as a gating system, organizing the formation of successive yet different neural assemblies
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Zheng, Jiaqi. "Interactive Visual Analytics for Agent-Based simulation : Street-Crossing Behavior at Signalized Pedestrian Crossing." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264991.
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To design a pedestrian crossing area reasonably can be a demanding task for traffic planners. There are several challenges, including determining the appropriate dimensions, and ensuring that pedestrians are exposed to the least risks. Pedestrian safety is especially obscure to analyze, given that many people in Stockholm cross the street illegally by running against the red light. To cope with these challenges, computational approaches of trajectory data visual analytics can be used to support the analytical reasoning process. However, it remains an unexplored field regarding how to visualize and communicate the street-crossing spatio-temporal data effectively. Moreover, the rendering also needs to deal with a growing data size for a more massive number of people. This thesis proposes a web-based interactive visual analytics tool for pedestrians' street-crossing behavior under various flow rates. The visualization methodology is also presented, which is then evaluated to have achieved satisfying communication and rendering effectiveness for maximal 180 agents over 100 seconds. In terms of the visualization scenario, pedestrians either wait for the red light or cross the street illegally; all people can choose to stop by a buffer island before they finish crossing. The visualization enables the analysis under multiple flow rates for 1) pedestrian movement, 2) space utilization, 3) crossing frequency in time-series, and 4) illegal frequency. Additionally, to acquire the initial trajectory data, Optimal Reciprocal Collision Avoidance (ORCA) algorithm is engaged in the crowd simulation. Then different visualization techniques are utilized to comply with user demands, including map animation, data aggregation, and time-series graph.<br>Att konstruera ett gångvägsområde kan rimligen vara en krävande uppgift för trafikplanerare. Det finns flera utmaningar, bland annat att bestämma lämpliga dimensioner och se till att fotgängare utsätts för minst risker. Fotgängarnas säkerhet är särskilt obskyrlig att analysera, eftersom många människor i Stockholm korsar gatan olagligt genom att springa mot det röda ljuset. För att klara av dessa utmaningar kan beräkningsmetoder för bana data visuell analys användas för att stödja den analytiska resonemangsprocessen. Det är emellertid ett oexplorerat fält om hur man visualiserar och kommunicerar gataövergången spatio-temporal data effektivt. Dessutom måste rendering också hantera en växande datastorlek för ett mer massivt antal människor. Denna avhandling föreslår ett webbaserat interaktivt visuellt analysverktyg för fotgängares gatöverföring under olika flödeshastigheter. Visualiseringsmetoden presenteras också, som sedan utvärderas för att ha uppnått tillfredsställande kommunikation och effektivitet för maximal 180 agenter över 100 sekunder. Vad beträffar visualiseringsscenariot, väntar fotgängare antingen på det röda ljuset eller tvärs över gatan; alla människor kan välja att stanna vid en buffertö innan de slutar korsa. Visualiseringen möjliggör analysen under flera flödeshastigheter för 1) fotgängarrörelse, 2) rymdutnyttjande, 3) korsfrekvens i tidsserier och 4) olaglig frekvens. För att förvärva den ursprungliga bana-data är Optimal Reciprocal Collision Avoidance (ORCA) algoritmen förknippad med folkmassimuleringen. Därefter utnyttjas olika visualiseringstekniker för att uppfylla användarnas krav, inklusive kartanimering, dataaggregering och tidsserier.
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Sztukowski, Lisa Ann. "Foraging ecology of the Campbell Albatross : individual specialisation and fishery interactions." Thesis, University of Plymouth, 2016. http://hdl.handle.net/10026.1/5377.
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Most albatrosses are critically endangered, endangered or vulnerable due to the deleterious impact of fisheries, pollution, introduced species, habitat alteration, and climate change. Foraging behaviour influences many aspects of seabird biology, and a detailed understanding of foraging ecology is required to better predict the impacts of significant changes to the marine environment. Campbell Albatross (Thalassarche impavida) is a threatened endemic, confined to a small number of locations on Campbell Island, New Zealand and was recently split from the closely related Black-browed Albatross (T. melanophrys). We currently lack much basic information on the foraging behaviour of this species, hindering our ability to understand how change may have occurred in the past and make predictions about it’s long-term future. First, I used GPS loggers and stable isotope analysis of blood to investigate how distribution and foraging effort (distance travelled and duration) varied with sex and breeding stage. I found that Campbell Albatrosses are sexually dimorphic and showed sex-specific foraging behaviour and habitat use – although this varied by stage of reproduction. Because males and females may be vulnerable to different threats, such as interactions with fisheries, I compared the spatial overlap and high resolution spatio-temporal overlaps between fisheries vessels and albatrosses within New Zealand’s Exclusive Economic Zone (EEZ). Albatrosses utilised 32% of the EEZ, however they overlapped with fisheries vessels in only 0.20% of the area. Previous research has demonstrated that the influence of fisheries vessels goes beyond the immediate location of the boat itself. Campbell Albatross have low levels of spatio-temporal overlap with fisheries – with males overlapping more than females. More generally, my results indicate that adding data on fine scale interactions will improve fisheries risk assessments, and provide information needed for the conservation and management of the Campbell Albatross. A key development in recent ecological research has been a greater appreciation that inter-individual variation in foraging behaviour can have profound population-level consequences. Accordingly I tested for individual differences in foraging behaviour in Campbell Albatrosses. The majority of individuals demonstrated both annual and inter-annual individual consistency in foraging locations, and the degree of specialisation was influenced by both sex and year. Consistent terminal latitude and longitude of foraging trips indicated high foraging area fidelity with a degree of flexibility in the fine-scale location. During brooding, females used the Campbell Plateau and showed more consistent behaviours than males, which tended to forage in the Southern Ocean. This adds to a growing body of evidence of individual foraging specialisation among seabirds in general and albatrosses in particular and reveals marked inter-individual differences in vulnerability to threats. In light of the evidence of individual foraging specialisations in the Campbell albatross, I also preformed a literature review of individual foraging specialisations across all seabirds. I found studies examining foraging specialisation for 35 species, with 28 (80%) providing evidence of consistent inter-individual differences (i.e. specialisation). Current studies suggest that specialisation is influenced by environmental variability and resource predictability, however, with limited data in tropical regions, more studies are needed to test these links. In summary, my thesis has provided new information on Campbell Albatross foraging ecology. Sex specific variations in behaviour and habitat use may influence conservation and management strategies. I have been able to contextualise the consistent individual differences in foraging distribution described for this species in light of global patterns of individual foraging specialisation in seabirds and highlight future areas of research.
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Bouba, Fanta. "Système d'information décisionnel sur les interactions environnement-santé : cas de la Fièvre de la Vallée du Rift au Ferlo (Sénégal)." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066461/document.
Full textAbstract:
Notre recherche se situe dans le cadre du projet QWECI (Quantifying Weather and Climate Impacts on Health in Developing Countries, UE FP7) en partenariat avec l’UCAD, le CSE et l’IPD, autour de la thématique environnement-santé avec comme cas pratique les maladies à vecteurs au Sénégal et plus particulièrement la Fièvre de la Vallée du Rift (FVR). La santé des populations humaines et animales est souvent fortement influencée par l’environnement. D’ailleurs, la recherche sur les facteurs de propagation des maladies à transmission vectorielle, telle que la FVR, prend en compte cette problématique dans sa dimension aussi bien physique que socio-économique. Apparue en 1912-1913 au Kenya, la FVR est une anthropo-zoonose virale répandue dans les régions tropicales qui concerne principalement les animaux mais dont les hommes peuvent aussi être touchés. Au Sénégal, la zone à risque concerne en majorité la vallée du fleuve Sénégal et la zone sylvo-pastorale du Ferlo. Bien que de climat sahélien, le Ferlo regorge de nombreuses mares qui sont des sources d’approvisionnement en eau pour les hommes et le bétail mais également les gîtes larvaires pour les vecteurs potentiels de la FVR. La maîtrise de la FVR, carrefour de trois (03) grands systèmes (agro-écologique, pathogène, économique/sanitaire/social), implique nécessairement la prise en compte de plusieurs paramètres si l’on veut d’abord comprendre les mécanismes d’émergence mais aussi envisager le travail de modélisation du risque. Notre travail porte sur le processus décisionnel pour quantifier l’utilisation de données sanitaires et environnementales dans l’évaluation de leur impact pour le suivi de la FVR. Les équipes de recherche impliquées produisent des données lors de leurs enquêtes de terrains et des analyses de laboratoire. Ce flot de données croissant devrait être stocké et préparé à des études corrélées grâce aux nouvelles techniques de stockage que sont les entrepôts de données. A propos de l’analyse des données, il ne suffit pas de s’appuyer seulement sur les techniques classiques telles que les statistiques. En effet, la valeur ajoutée de contribution sur la question s’oriente vers une analyse prédictive combinant à la fois les techniques agrégées de stockage et des outils de traitement. Ainsi, pour la découverte d’informations, nouvelles et pertinentes à priori non évidentes, il est nécessaire de s’orienter vers la fouille de données. Par ailleurs, l’évolution de la maladie étant fortement liée à la dynamique spatio-temporelle environnementale des différents acteurs (vecteurs, virus et hôtes), cause pour laquelle nous nous appuyons sur les motifs spatio-temporels pour identifier et mesurer certaines interactions entre les paramètres environnementaux et les acteurs impliqués. Grâce au processus décisionnel, les résultats qui en découlent sont multiples :i. suivant la formalisation de la modélisation multidimensionnelle, nous avons construit un entrepôt de données intégré qui regroupe l’ensemble des objets qui participent à la gestion du risque sanitaire – ce modèle peut être généralisé aux maladies à vecteurs ;ii. malgré une très grande variété de moustiques, les Culex de type neavei et les Aedes de type ochraceus et vexans sont les vecteurs potentiels de la FVR les plus présents dans la zone d’étude et ce, durant la saison des pluies, période la plus sujette à des cas suspects ; la période à risque reste quand même le mois d’octobre ;iii. les mares analysées ont quasiment le même comportement, mais des variations significatives subsistent par endroits.Ce travail de recherche démontre une fois de plus l’intérêt pour la mise en évidence des relations entre les données environnementales et la FVR à partir de méthodes de fouille de données, pour la surveillance spatio-temporelle du risque d’émergence<br>Our research is in part of the QWeCI european project (Quantifying Weather and Climate Impacts on Health in Developing Countries, EU FP7) in partnership with UCAD, the CSE and the IPD, around the theme of environmental health with the practical case on vector-borne diseases in Senegal and particularly the Valley Fever (RVF). The health of human and animal populations is often strongly influenced by the environment. Moreover, research on spread factors of vector-borne diseases such as RVF, considers this issue in its dimension both physical and socio-economic. Appeared in 1912-1913 in Kenya, RVF is a widespread viral anthropo-zoonosis in tropical regions which concerns animals but men can also be affected. In Senegal, the risk area concerns mainly the Senegal River Valley and the forestry-pastoral areas Ferlo. With a Sahelian climate, the Ferlo has several ponds that are sources of water supply for humans and livestock but also breeding sites for potential vectors of RVF. The controlling of the RVF, which is crossroads of three (03) large systems (agro-ecological, pathogen, economic/health/social), necessarily entails consideration of several parameters if one wants to first understand the mechanisms emergence but also consider the work on risk modeling. Our work focuses on the decision making process for quantify the use of health data and environmental data in the impact assessment for the monitoring of RVF. Research teams involved produce data during their investigations periods and laboratory analyzes. The growing flood of data should be stored and prepared for correlated studies with new storage techniques such as datawarehouses. About the data analysis, it is not enough to rely only on conventional techniques such as statistics. Indeed, the contribution on the issue is moving towards a predictive analysis combining both aggregate storage techniques and processing tools. Thus, to discover information, it is necessary to move towards datamining. Furthermore, the evolution of the disease is strongly linked to environmental spatio-temporal dynamics of different actors (vectors, viruses, and hosts), cause for which we rely on spatio-temporal patterns to identify and measure interactions between environmental parameters and the actors involved. With the decision-making process, we have obtained many results :i. following the formalization of multidimensional modeling, we have built an integrated datawarehouse that includes all the objects that are involved in managing the health risk - this model can be generalized to others vector-borne diseases;ii. despite a very wide variety of mosquitoes, Culex neavei, Aedes ochraceus and Aedes vexans are potential vectors of FVR. They are most present in the study area and, during the rainy season period which is most prone to suspected cases; the risk period still remains the month of October;iii. the analyzed ponds have almost the same behavior, but significant variations exist in some points.This research shows once again the interest in the discovery of relationships between environmental data and the FVR with datamining methods for the spatio-temporal monitoring of the risk of emergence
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Östergård, Hannah. "Plant-seed predator interactions – ecological and evolutionary aspects." Doctoral thesis, Stockholm University, Department of Botany, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7537.
Full textAbstract:
<p>Plant-animal interactions are affected by both abundance and distribution of interacting species and the community context in which they occur. However, the relative importance of these factors is poorly known. I examined the effects of predator host range, environmental factors, host plant populations, plant traits and fruit abortion on the intensity of pre-dispersal seed predation in 46 host populations of the perennial herb <i>Lathyrus vernus</i>. I recorded damage by beetle pre-dispersal seed predators, mainly <i>Apion opeticum </i>and <i>Bruchus atomarius</i> with different host ranges on <i>L. vernus</i> as well as on two additional host plants. Local seed predator population size was mainly influenced by plant population size, current seed production and beetle population size in the previous year, but was not strongly affected by connectivity. The monophagous seed predator was less abundant and had lower densities than the oligophagous. Both predator species had a strong ability to track fluctuations in seed production; intensity of predation increased with relative increases in seed production. Oligophagous predation on<i> L. vernus i</i>ncreased with the abundance of alternative hosts, but presence of<i> L. vernus</i> did not affect predation on alternative hosts. Abundances and trait preferences differed among three co-occurring seed predators, but were also associated with the abundance of the other species. Overall, seed predation influenced selection on flower number. I found clear indications of seed predator offence but no obvious plant defence. The pattern of fruit abortion was associated with reduced plant fitness since the seed predator had an advanced ability to locate fruits with high probability of retention. Taken together, different factors influencing abundance of the seed predator species, different preferences, and context dependent trait selection are likely to result in complex spatio-temporal variation in overall seed losses and trait selection in the common host plant.</p>
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Escalle, Lauriane. "Spatio-temporal interactions between whale sharks, cetaceans and tropical tuna purse-seine fisheries, within a conservation perspective, in the Atlantic and Indian Oceans." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT125/document.
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Dans le cadre de l’Approche Ecosystémique des Pêches (AEP), il est nécessaire d’évaluer l’impact de la pêche thonière tropicale à la senne sur les espèces ciblées et sur les espèces accessoires. Parmi ces dernières, les espèces de la mégafaune, telles que des requins, raies, cétacés, tortues, oiseaux marins, sont souvent emblématiques et vulnérables. Les thoniers senneurs tropicaux recherchent activement à la surface de l’eau tout indice de la présence de bancs de thon (e.g. oiseaux, objets flottants, baleines, dauphins ou requins baleines). Dans l’est de l’océan Atlantique et l’ouest de l’océan Indien, les deux modes de pêches principaux sont les captures de thons en bancs libres et celles sur bancs associés à un objet flottant, naturel ou artificiel, rassemblés ici sur sous le terme de dispositif de concentration de poisson (DCP). Les calées associées aux requins baleines et aux cétacés sont toutefois peu étudiées. L’objectif de cette thèse est donc d’analyser les co-occurrences et/ou interactions spatio-temporelles entre requins baleines, cétacés et pêche thonière à la senne, dans une perspective de conservation de l’écosystème. Ce travail, basé sur des données de livres de bord et d’observateurs scientifiques embarqués, a montré que la co-occurrence pêche thonière/ mégafaune se localise dans des strates spatio-temporelles relativement précises: i) du Gabon à l’Angola (avril–septembre), ii) dans le Canal du Mozambique (juin–septembre) et iii) à l’est des Seychelles (avril–septembre). Les baleines et requins baleines étant planctivores, la co-occurrence avec la pêche à la senne est principalement liée à une forte productivité primaire (appréhendée à travers des proxys tels que la concentration en chlorophylle-a). De plus, les calées sur ces deux groupes étaient assez élevées avant 2000 (jusqu’à 20% des calées), et qu’elles sont moins fréquentes aujourd’hui (AC3 et 1,5% des calées associées à des baleines et des requins baleines, respectivement). L’impact de la pêche à la senne sur ces espèces semble relativement faible au regard du taux de mortalité apparente de 1,4% pour les requins baleines et 5,6% pour les cétacés. Des marquages satellites réalisés sur les requins baleines, confirment ces observations sur le plus long terme, mais la taille de l’échantillon limite la formulation de conclusions définitives. Concernant les dauphins, bien que présents sur les zones de pêche, ils interagissent très peu avec celle-ci, soulignant ainsi une différence majeure avec l’océan Pacifique est où ce mode de pêche est majoritaire. La diversité spécifique des espèces cible et accessoire associées aux calées sur mégafaune a également été étudiée. Les requins baleines sont associés aux listaos et à l’albacore (dans une large gamme de tailles), alors que les baleines le sont principalement à de gros albacores. De plus, la capture accessoire associée à ces deux groupes de mégafaune est relativement faible et dominée par le requin soyeux et la diversité spécifique est proche de celle trouvée sous les bancs libres de thons. Enfin les effets de mesures de conservation vis-à-vis de la mégafaune encerclée ou de mesures de gestion de l’effort de pêche, notamment les moratoires sur DCP réelles ou simulées (e.g. moratoires élargis), ont été analysés. Les premières ont eu un effet limité en terme de captures cibles et accessoires, alors que les moratoires impactent peu le nombre de calées associés à la mégafaune, ceci en raison du décalage spatio-temporel des co-occurrences. Cependant des moratoires élargis pourraient être bénéfiques pour les thons juvéniles et certaines espèces associées. Par l’analyse quantitative des interactions entre la pêche thonière à la senne et la mégafaune, cette thèse apporte des connaissances essentielles sur les espèces étudiées dans le cadre de la mise en place d’une AEP, applicable à la pêche thonière tropicale<br>In the frame of the Ecosystem Approach to Fishery (EAF) management, impact of the tropical tuna purse-seine fishery on targeted and incidentally captured species should be investigated. They may include megafauna species, such as sharks, rays, cetaceans, turtles or sea birds, which often are emblematic and vulnerable species. Tropical tuna purse-seiners actively search, at the surface of the sea, for clues indicating the presence of tuna schools (e.g. birds, floating objects, whales, dolphins or whale sharks). In the eastern Atlantic and western Indian Oceans, the main two fishing modes are sets on free swimming tuna schools and schools associated to natural or artificial floating objects, thereafter called Fish Aggregating Device (FAD). However dedicated studies on fishing sets associated to whale sharks and cetaceans are still lacking. The aim of this thesis is therefore, using logbook and scientific onboard observer data, to investigate the spatio-temporal co-occurrences and/or interactions between whale sharks, cetaceans and the tuna purse-seine fishery within an ecosystem conservation perspective. This work underlines that the megafauna/ fishery co-occurrence occurs in specific spatio-temporal strata: i) Gabon to Angola (April–September), ii) the Mozambique Channel (June–September), and iii) East of Seychelles (April–September). As baleen whales and whale sharks are filter feeders, the co-occurrence with the purse-seine fishery was mostly linked to highly productive environments (i.e. using proxys including chlorophyll-a concentration). In addition fishing sets involving megafauna were relatively high before 2000 (up to 20% of the sets), but are nowadays less frequent (AC3 and 1.5% of the sets associated to baleen whales and whale sharks). The purse-seine fishery appears to have a relatively low impact on megafauna species with mortality rates of 1.4% for whale sharks and 5.6% for cetaceans. Whale shark satellite tagging also confirms these results on the longer term, but the low sample size precludes any final conclusion. While dolphins are present in fishing areas, very few interactions with the fishery was detected, which highlights the striking difference with the eastern Pacific Ocean where half the sets are associated to dolphin herds. In addition, the diversity of targeted and bycatch species captured under whale shark and baleen whale sets was also investigated. Whale sharks are principally associated to skipjack and yellowfin (of various sizes) tunas and baleen whales mostly to large yellowfin tuna. In addition, bycatch species associated to these two megafauna groups was relatively low and dominated by the silky shark, and bycatch diversity was close to the one found for free swimming tuna schools. Finally, real and/or simulated encircled megafauna conservation measures or fishing effort management measures (especially FAD moratoria including larger ones) were investigated. The first ones were found to have limited consequences on tuna catch and bycatch. Conversely FAD moratoria had limited impacts on the number of megafauna associated fishing sets, due to the fact that the main spatio-temporal strata of megafauna and FAD sets differ. However larger and longer moratoria could be beneficial for juvenile tuna and some bycatch species. Overall, this thesis has lead to increase the knowledge on megafauna/ fishery interactions, essential in the general framework of setting up an EAF in the tropical tune purse-seine fishery
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Sonebo, Christina, and Joel Ekelöf. "Creating and Evaluating an Interactive Visualization Tool For Crowd Trajectory Data." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229756.
Full textAbstract:
There is currently no set standard for evaluating visualization environments. Even though the number of visualizations has increased, there is a tendency to overlook the evaluation of their usability. This thesis investigates how a visualization tool for crowd trajectory data can be made using the visualization technique of animated maps and the JavaScript library D3.js. Furthermore it explores how such a visualization tool can be evaluated according to a suggested framework for spatio-temporal data. The developed tool uses data taken from the UCY Graphics Lab, consisting of 415 trajectories collected from a video recorded at a campus area. User evaluation was performed through a user test with a total of six participants, measuring effectiveness as completed tasks, and satisfaction as ease of use for three different amounts of trajectories. Qualitative data was recorded through using the think aloud protocol to gather feedback to further improve the implementation. The evaluation shows that the visualization tool is usable and effective, and that the technique of animated maps in combination with a heatmap can aid users when exploring and formulating ideas about data of this kind. It is also concluded that the framework is a possible tool to utilize when validating visualization systems for crowd trajectory data.<br>Det finns i dagsläget ingen etablerad standard för att utvärdera visualiseringssystem. Även om antalet visualiseringar har ökat finns det en tendens att förbise utvärderandet av deras användbarhet. I det här arbetet undersöker vi hur ett visualiseringsverktyg för data av gångbanor hos folksamlingar kan skapas, med hjälp utav visualiseringsmetoden animated maps och JavaScript-biblioteket D3.js. Vidare undersöker vi hur det är möjligt att evaluera ett visualiseringsverktyg utefter ett givet ramverk. Visualiseringsverktyget använder data från UCY Graphics Lab. Datan består av 415 gångbanor som är insamlade från en videoinspelning av ett campusområde. En utvärdering genomfördes sedan med sex deltagare, där visualiseringens effektivitet och användarvänlighet mättes. Frågorna ställdes för tre olika mängder av gångbanor. Kvalitativa data dokumenterades genom en så kallad ''think aloud'', för att ge återkoppling och förslag på möjliga förbättringar av visualiseringen. Evalueringen visar på att animated maps i kombination med en heatmap kan hjälpa användare att utforska data av gångbanor hos folksamlingar, samt att verktyget är effektivt och användbart. Det är också visat att det ramverk som användes vid evalueringen är ett möjligt verktyg för att validera visualiseringsverktyg av den typ som gjorts i det här projektet.
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Shiponeni, Ndafuda Nangula. "Spatio-temporal distribution of grass and shrubs at the ecotone between an arid grassland and succulent shrubland : ecological interactions and the influence of soils." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/10663.
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Includes bibliographical references (p. 110-122).<br>This thesis presents ecological investigations of vegetation at an ecotone between the Namaqualand shrublands and Bushmanland arid grassland at the climatic transition between the predominantly winter rainfall Succulent Karoo and the predominantly summer rainfall Nama-Karoo biomess. The work focused on the determinants of grass and succulent shrub vegetation characterising the ecotone, and on determining the current and past distribution of this vegetation. A combination of detailed community the current and past distribution of this vegetation. A combination of detailed community level investigations (both observational and experimental), and a variety of remotely sensed data and techniques were applied to capture processes and patterns at different scales. In the first set of investigations, I have investigated the role of soil and competition on vegetation patterns. Secondly, field data were combined with remote sensing technology to establish the current distribution of grasses and shrubs along the ecotone, and to determine how this vegetation has changed over the past 20 years.
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Taie, Semiromi Majid [Verfasser]. "Analysis and projection of spatio-temporal drought and climate change impacts on groundwater resources and surface-groundwater interactions for three Iranian case studies / Majid Taie Semiromi." Kassel : Universitätsbibliothek Kassel, 2020. http://d-nb.info/1231409320/34.
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Bouba, Fanta. "Système d'information décisionnel sur les interactions environnement-santé : cas de la Fièvre de la Vallée du Rift au Ferlo (Sénégal)." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066461.
Full textAbstract:
Notre recherche se situe dans le cadre du projet QWECI (Quantifying Weather and Climate Impacts on Health in Developing Countries, UE FP7) en partenariat avec l’UCAD, le CSE et l’IPD, autour de la thématique environnement-santé avec comme cas pratique les maladies à vecteurs au Sénégal et plus particulièrement la Fièvre de la Vallée du Rift (FVR). La santé des populations humaines et animales est souvent fortement influencée par l’environnement. D’ailleurs, la recherche sur les facteurs de propagation des maladies à transmission vectorielle, telle que la FVR, prend en compte cette problématique dans sa dimension aussi bien physique que socio-économique. Apparue en 1912-1913 au Kenya, la FVR est une anthropo-zoonose virale répandue dans les régions tropicales qui concerne principalement les animaux mais dont les hommes peuvent aussi être touchés. Au Sénégal, la zone à risque concerne en majorité la vallée du fleuve Sénégal et la zone sylvo-pastorale du Ferlo. Bien que de climat sahélien, le Ferlo regorge de nombreuses mares qui sont des sources d’approvisionnement en eau pour les hommes et le bétail mais également les gîtes larvaires pour les vecteurs potentiels de la FVR. La maîtrise de la FVR, carrefour de trois (03) grands systèmes (agro-écologique, pathogène, économique/sanitaire/social), implique nécessairement la prise en compte de plusieurs paramètres si l’on veut d’abord comprendre les mécanismes d’émergence mais aussi envisager le travail de modélisation du risque. Notre travail porte sur le processus décisionnel pour quantifier l’utilisation de données sanitaires et environnementales dans l’évaluation de leur impact pour le suivi de la FVR. Les équipes de recherche impliquées produisent des données lors de leurs enquêtes de terrains et des analyses de laboratoire. Ce flot de données croissant devrait être stocké et préparé à des études corrélées grâce aux nouvelles techniques de stockage que sont les entrepôts de données. A propos de l’analyse des données, il ne suffit pas de s’appuyer seulement sur les techniques classiques telles que les statistiques. En effet, la valeur ajoutée de contribution sur la question s’oriente vers une analyse prédictive combinant à la fois les techniques agrégées de stockage et des outils de traitement. Ainsi, pour la découverte d’informations, nouvelles et pertinentes à priori non évidentes, il est nécessaire de s’orienter vers la fouille de données. Par ailleurs, l’évolution de la maladie étant fortement liée à la dynamique spatio-temporelle environnementale des différents acteurs (vecteurs, virus et hôtes), cause pour laquelle nous nous appuyons sur les motifs spatio-temporels pour identifier et mesurer certaines interactions entre les paramètres environnementaux et les acteurs impliqués. Grâce au processus décisionnel, les résultats qui en découlent sont multiples :i. suivant la formalisation de la modélisation multidimensionnelle, nous avons construit un entrepôt de données intégré qui regroupe l’ensemble des objets qui participent à la gestion du risque sanitaire – ce modèle peut être généralisé aux maladies à vecteurs ;ii. malgré une très grande variété de moustiques, les Culex de type neavei et les Aedes de type ochraceus et vexans sont les vecteurs potentiels de la FVR les plus présents dans la zone d’étude et ce, durant la saison des pluies, période la plus sujette à des cas suspects ; la période à risque reste quand même le mois d’octobre ;iii. les mares analysées ont quasiment le même comportement, mais des variations significatives subsistent par endroits.Ce travail de recherche démontre une fois de plus l’intérêt pour la mise en évidence des relations entre les données environnementales et la FVR à partir de méthodes de fouille de données, pour la surveillance spatio-temporelle du risque d’émergence<br>Our research is in part of the QWeCI european project (Quantifying Weather and Climate Impacts on Health in Developing Countries, EU FP7) in partnership with UCAD, the CSE and the IPD, around the theme of environmental health with the practical case on vector-borne diseases in Senegal and particularly the Valley Fever (RVF). The health of human and animal populations is often strongly influenced by the environment. Moreover, research on spread factors of vector-borne diseases such as RVF, considers this issue in its dimension both physical and socio-economic. Appeared in 1912-1913 in Kenya, RVF is a widespread viral anthropo-zoonosis in tropical regions which concerns animals but men can also be affected. In Senegal, the risk area concerns mainly the Senegal River Valley and the forestry-pastoral areas Ferlo. With a Sahelian climate, the Ferlo has several ponds that are sources of water supply for humans and livestock but also breeding sites for potential vectors of RVF. The controlling of the RVF, which is crossroads of three (03) large systems (agro-ecological, pathogen, economic/health/social), necessarily entails consideration of several parameters if one wants to first understand the mechanisms emergence but also consider the work on risk modeling. Our work focuses on the decision making process for quantify the use of health data and environmental data in the impact assessment for the monitoring of RVF. Research teams involved produce data during their investigations periods and laboratory analyzes. The growing flood of data should be stored and prepared for correlated studies with new storage techniques such as datawarehouses. About the data analysis, it is not enough to rely only on conventional techniques such as statistics. Indeed, the contribution on the issue is moving towards a predictive analysis combining both aggregate storage techniques and processing tools. Thus, to discover information, it is necessary to move towards datamining. Furthermore, the evolution of the disease is strongly linked to environmental spatio-temporal dynamics of different actors (vectors, viruses, and hosts), cause for which we rely on spatio-temporal patterns to identify and measure interactions between environmental parameters and the actors involved. With the decision-making process, we have obtained many results :i. following the formalization of multidimensional modeling, we have built an integrated datawarehouse that includes all the objects that are involved in managing the health risk - this model can be generalized to others vector-borne diseases;ii. despite a very wide variety of mosquitoes, Culex neavei, Aedes ochraceus and Aedes vexans are potential vectors of FVR. They are most present in the study area and, during the rainy season period which is most prone to suspected cases; the risk period still remains the month of October;iii. the analyzed ponds have almost the same behavior, but significant variations exist in some points.This research shows once again the interest in the discovery of relationships between environmental data and the FVR with datamining methods for the spatio-temporal monitoring of the risk of emergence
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Zaukevičius, Audrius. "The use of angular dispersion for formation of high peak power and ultrashort pulsed light beams in nonlinear interactions." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20121227_090300-84220.
Full textAbstract:
This thesis is aimed to provide an extensive picture of the phenomena encountered in optical parametric amplification of pulsed light beams. The particular attention is paid for the spatio-temporal dynamics of the pulsed light beams being amplified. All the research has been done by means of numerical methods. The equations used in the model were derived from the Maxwell’s equations and the assumptions made along the derivation of equations were discussed. Using the presented model it has been numerically demonstrated, that in noncollinear optical parametric amplifier, when pulse fronts of pump and signal are not matched, the signal pulse becomes tilted and aside from angular dispersion acquires a spatial chirp. It has been shown, that the magnitudes of the induced spatial and angular dispersions decrease at different rates with the increase of the signal pulse temporal chirp. The main results of this study were verified experimentally. Additionally, in this thesis we have proposed a novel and versatile method for pulsed conical wave parametric amplification with subsequent spatio-temporal compression during propagation in free space. It allows to form ultra-intense and propagation invariant wave-packets capable to propagate over many Rayleigh range in the desired material. In contrast to ordinary chirped-pulse amplification technique it does not require a pulse compressor, thus greatly facilitates the parametric amplification of few-cycle light pulses.<br>Disertacija yra skirta išnagrinėti ir paaiškinti impulsinių šviesos pluoštų parametrinio stiprinimo metu vykstančius reiškinius. Ypatingas dėmesys yra skiriamas erdvinei-laikinei impulsinio šviesos pluošto dinamikai stiprinimo metu. Visi nagrinėjamų reiškinių tyrimai buvo atliekami taikant skaitmeninio modeliavimo metodus. Modelyje panaudotos lygtys buvo išvestos iš Maksvelo lygčių, išsamiai aptariant lygčių išvedimo metu daromas prielaidas. Naudojantis pateiktu modeliu buvo gauti skaitmeniniai rezultatai, kurie parodė, jog nekolineariame parametriniame stiprintuve, kuomet kaupinimo ir signalinio impulsų frontai nėra sutapatinti, signalinis impulsas tampa pakrypęs ir be kampinės dispersijos taip pat įgyja ir erdvinį čirpą. Nustatyta, kad indukuotų erdvinės ir kampinės dispersijų mažėjimo sparta, didinant signalinio impulso laikinį čirpą, yra skirtinga. Pagrindiniai šio teorinio tyrimo rezultatai buvo patvirtinti eksperimentiškai. Taip pat šioje disertacijoje yra pristatomas naujas ir universalus impulsinių kūginių bangų parametrinio stiprinimo metodas, kuriame sustiprinti impulsai patys susispaudžia laike ir erdvėje paprasčiausiai sklisdami laisvoje erdvėje. Šis metodas leidžia formuoti didelio smailinio intensyvumo invariantiškus bangų paketus, galinčius nusklisti daugelį Relėjaus nuotolių norimoje medžiagoje. Priešingai nei įprastame čirpuotų impulsų stiprinimo metode, šis metodas nereikalauja impulsų spaustuvo, o tai žymiai palengvina parametrinį kelių optinių ciklų... [toliau žr. visą tekstą]
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Venkatachalapathy, Muthukumaran [Verfasser], Leif [Akademischer Betreuer] Dehmelt, and Jan Georg [Gutachter] Hengstler. "Development and application of methods for spatio-temporal perturbation and analysis of protein interactions via intracellular protein microarrays / Muthukumaran Venkatachalapathy. Betreuer: Leif Dehmelt. Gutachter: Jan Georg Hengstler." Dortmund : Universitätsbibliothek Dortmund, 2016. http://d-nb.info/1112560777/34.
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Do, Thi Phuong Thao. "Apport de la télédétection spatiale pour l'étude multiscalaire des interactions climat-surface en Afrique de l'Ouest : étude du bassin versant de l'Ouémé supérieur (Bénin)." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU025/document.
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Cette thèse s'inscrit dans le cadre du programme international AMMA (Analyse Multidisciplinaire de la Mousson Africaine) dont un des objectifs est de mieux connaître les dynamiques régionales des interactions climat-environnement-société. Elle est une contribution à l'étude de la variabilité spatio-temporelle de la végétation, en fonction des différents types d'occupation du sol et sous contrainte des variations saisonnières et interannuelles de la pluviométrie sur la partie supérieure du bassin versant du fleuve Ouémé, au Bénin. Cette espace possède un important réseau de surveillance hydroclimatique au sol, l'observatoire AMMA-Catch, qui fournit de nombreuses données in situ. L'analyse s'appuie aussi sur différentes données issues de la télédétection satellitaire optique (LANDSAT, SPOT-VGT, MODIS, MSG-SEVIRI ou ECOCLIMAP) pour l'étude de l'occupation du sol, de la variabilité photosynthétique de la végétation ou des estimations pluviométriques (RFE – Rainfall Estimate). L'étude porte principalement sur trois questions : 1) les modifications des états de surface récemment observées dans cette zone expérimentale de l'Ouémé supérieur ; 2) la valorisation des différentes données issues de la télédétection satellitaire pour diagnostiquer la variabilité bioclimatique régionale de la végétation ; 3) la compréhension des interactions à l'interface climat/végétation, pour interpréter certaines variations bioclimatiques intra- et interannuelles en fonction des principaux états de surface. Les principaux résultats suggèrent qu'il est possible de discriminer des relations fonctionnelles selon les principaux états de surface forestiers ou très anthropisés. Les analyses diachroniques par classification d'images Landsat (ETM+) montrent que les espaces cultivés enregistrent régionalement une augmentation de 25 % sur la période 2003-2012. Les superficies de jachère diminuent, alors que les savanes arbustives augmentent. Tous les espaces forestiers perdent en superficie sur la décennie observée, en particulier les forêts denses (a priori protégées dans cette région) avec une baisse supérieure à 16 %. La variabilité spatio-temporelle d'un indice de végétation (NDVI) est significativement dépendante des trois principaux modes d'occupation du sol, même si l'artefact dû à la nébulosité complique les analyses et interprétations. Les contrastes entre le domaine de forêt naturelle encore préservée (la forêt classée) et les espaces en mutation agricole (cultures et jachères) sont particulièrement visibles. Sur la décennie 2002-2012, il n'y a pas de tendance des pluies, mais plutôt une succession de phases sèches et humides, qui induisent finalement une stabilité interannuelle du NDVI. Le déphasage moyen entre pluies et activité végétale est en moyenne de quatre décades, mais il semble que la fin de la saison végétative recule ait reculé d'au moins 10 jours sur la période étudiée, traduisant une modification des précipitations de fin d'année<br>This thesis is part of the international AMMA program (Analyse Multidisciplinaire de la Mousson Africaine - Multidisciplinary Analysis of African Monsoon) whose objective is to better understand the regional dynamics of climate-environment-society interactions. It is a contribution to the study of the spatio-temporal variability of vegetation, according to different land use types and under the constraints of seasonal and interannual variations in rainfall in the upper basin of Ouémé river, Benin. This area has an extensive network of hydro-climatic ground monitoring, observatory AMMA-Catch, which provides many in-situ data. The analysis also relies on data from different optical remote sensing satellites (LANDSAT, SPOT-VGT, MODIS, MSG-SEVIRI or ECOCLIMAP) for the study of land occupation, variability of photosynthetic vegetation or rainfall estimate (RFE). The study focuses mainly on three questions: 1) the changes in surface conditions recently observed in the experimental area of upper Ouémé; 2) the analysis of various data from satellite remote sensing to diagnose regional bioclimatic variability of vegetation; 3) the understanding of climate/vegetation interface interactions, in order to interpret certain intra-and interannual bioclimatic variations depending on the main surface conditions. The main results suggest that it is possible to discriminate the functional relationships from the main conditions of forest or anthropized surface. The diachronic analysis through the classification of Landsat (ETM +) images show that the cultivated areas recorded regionally an increase of 25% over the period of 2003-2012. The areas of set-aside decrease, while shrublands increase. All forests lost in area over the decade observed, particularly dense forest (presumably protected in this region) with a drop of over 16%. The spatio-temporal variability of a vegetation index (NDVI) significantly depends on three main types of land use, even though the noise due to the cloud cover complicates the analysis and interpretation. The contrasts between the preserved natural forest area (the forest reserve) and the agricultural areas (crops and fallow) are particularly visible. Over the decade 2002-2012, there is no trend of rainfall, but rather a succession of wet and dry phases, which ultimately induce an interannual stability of NDVI. The average phase difference between rainfall and vegetation activity is four decades, but it seems that the end of the vegetation growing season has retreated back to at least 10 days during the study period, reflecting a change in rainfall at the end of the year
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Rudhall, Andrew Peter. "Ultrashort laser pulse shaping for novel light fields and experimental biophysics." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3682.
Full textAbstract:
Broadband spectral content is required to support ultrashort pulses. However this broadband content is subject to dispersion and hence the pulse duration of corresponding ultrashort pulses may be stretched accordingly. I used a commercially-available adaptive ultrashort pulse shaper featuring multiphoton intrapulse interference phase scan technology to characterise and compensate for the dispersion of the optical system in situ and conducted experimental and theoretical studies in various inter-linked topics relating to the light-matter interaction. Firstly, I examined the role of broadband ultrashort pulses in novel light-matter interacting systems involving optically co-trapped particle systems in which inter-particle light scattering occurs between optically-bound particles. Secondly, I delivered dispersion-compensated broadband ultrashort pulses in a dispersive microscope system to investigate the role of pulse duration in a biological light-matter interaction involving laser-induced cell membrane permeabilisation through linear and nonlinear optical absorption. Finally, I examined some of the propagation characteristics of broadband ultrashort pulse propagation using a computer-controlled spatial light modulator. The propagation characteristics of ultrashort pulses is of paramount importance for defining the light-matter interaction in systems. The ability to control ultrashort pulse propagation by using adaptive dispersion compensation enables chirp-free ultrashort pulses to be used in experiments requiring the shortest possible pulses for a specified spectral bandwidth. Ultrashort pulsed beams may be configured to provide high peak intensities over long propagation lengths, for example, using novel beam shapes such as Bessel-type beams, which has applications in biological light-matter interactions including phototransfection based on laser-induced cell membrane permeabilisation. The need for precise positioning of the beam focus on the cell membrane becomes less strenuous by virtue of the spatial properties of the Bessel beam. Dispersion compensation can be used to control the temporal properties of ultrashort pulses thus permitting, for example, a high peak intensity to be maintained along the length of a Bessel beam, thereby reducing the pulse energy required to permeabilise the cell membrane and potentially reduce damage therein.
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Le, Guyader Damien. "Modélisation des activités humaines en mer côtière." Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00717420.
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Les mers côtières jouent un rôle essentiel pour les sociétés humaines. Mais la concentration et la diversité des activités qui s'y développent exercent une pression croissante sur cet espace et les milieux associés en générant des interactions parfois conflictuelles entre activités. La compréhension de ces interactions constitue un enjeu en termes de recherche et pour la société civile. Une méthodologie visant à décrire la distribution spatio-temporelle de différentes activités en mer côtière est donc conçue et mise en œuvre en rade de Brest. La collecte de données spatiales, temporelles, quantitatives et qualitatives combine l'analyse de bases de données spatio-temporelles comme celles issues du Système d'Identification Automatique (AIS), et le dépouillement d'entretiens semi-directifs menés auprès de personnes-ressources. À partir des données hétérogènes collectées, une information structurée dans une base de données spatio-temporelle (BDST) est produite. Dans un premier temps, son exploitation cartographique par un Système d'Information Géographique (SIG) permet la réalisation d'instantanés au pas de temps quotidien sur l'ensemble d'une année. La qualité de l'information temporelle et quantitative puis la nature et la source de l'information spatiale sont renseignées. Dans un second temps, la BDST est mobilisée pour identifier, spatialiser et quantifier les conflits d'usages potentiels et les interactions spatio-temporelles potentielles négatives entre les activités considérées en rade de Brest.
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Bourdis, Nicolas. "Détection de changements entre vidéos aériennes avec trajectoires arbitraires." Phd thesis, Telecom ParisTech, 2013. http://tel.archives-ouvertes.fr/tel-00834717.
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Les activités basées sur l'exploitation de données vidéo se sont développées de manière fulgurante ces dernières années. En effet, non seulement avons-nous assisté à une démocratisation de certaines de ces activités, telles que la vidéo-surveillance, mais également à une diversification importante des applications opérationnelles (e.g. suivi de ressources naturelles, reconnaissance aérienne et bientôt satellite). Cependant, le volume de données vidéo généré est aujourd'hui astronomique et l'efficacité des activités correspondantes est limitée par le coût et la durée nécessaire à l'interprétation humaine de ces données vidéo. Par conséquent, l'analyse automatique de flux vidéos est devenue une problématique cruciale pour de nombreuses applications. Les travaux réalisés dans le cadre de cette thèse s'inscrivent dans ce contexte, et se concentrent plus spécifiquement sur l'analyse automatique de vidéos aériennes. En effet, outre le problème du volume de données, ce type de vidéos est particulièrement difficile à exploiter pour un analyste image, du fait des variations de points de vue, de l'étroitesse des champs de vue, de la mauvaise qualité des images, etc. Pour aborder ces difficultés, nous avons choisi de nous orienter vers un système semi-automatique permettant d'assister l'analyste image dans sa tâche, en suggérant des zones d'intérêt potentiel par détection de changements. Plus précisément, l'approche développée dans le cadre de cette thèse cherche à exploiter les données disponibles au maximum de leur potentiel, afin de minimiser l'effort requis pour l'utilisateur et de maximiser les performances de détection. Pour cela, nous effectuons une modélisation tridimensionnelle des apparences observées dans les vidéos de référence. Cette modélisation permet ensuite d'effectuer une détection en ligne des changements significatifs dans une nouvelle vidéo, en identifiant les déviations d'apparence par rapport aux modèles de référence. Des techniques spécifiques ont également été proposées pour effectuer l'estimation des paramètres d'acquisition ainsi que l'atténuation des effets de l'illumination. De plus, nous avons développé plusieurs techniques de consolidation permettant d'exploiter la connaissance a priori relative aux changements à détecter. L'intérêt de notre approche de détection de changements est démontré dans ce manuscrit de thèse, par la présentation des résultats issus de son évaluation minutieuse et systématique. Cette évaluation a été effectuée à l'aide de données réelles et synthétiques permettant d'analyser, d'une part la robustesse de l'approche par rapport à des perturbations réalistes (e.g. bruit, artefacts de compression, apparences et effets complexes, etc), et d'autre part la précision des résultats en conditions contrôlées.
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Bourdis, Nicolas. "Détection de changements entre vidéos aériennes avec trajectoires arbitraires." Electronic Thesis or Diss., Paris, ENST, 2013. http://www.theses.fr/2013ENST0028.
Full textAbstract:
Les activités basées sur l'exploitation de données vidéo se sont développées de manière fulgurante ces dernières années : nous assisté à une démocratisation de certaines de ces activités (vidéo-surveillance) mais également à une diversification importante des applications opérationnelles (suivi de ressources naturelles, reconnaissance etc). Cependant, le volume de données vidéo généré est aujourd'hui astronomique et l'efficacité de ces activités est limitée par le coût et la durée nécessaire à l'interprétation humaine des données vidéo. L'analyse automatique de flux vidéos est donc devenue une problématique cruciale pour de nombreuses applications. L'approche semi-automatique développée dans le cadre de cette thèse se concentre plus spécifiquement sur l'analyse de vidéos aériennes, et permet d'assister l'analyste image dans sa tâche en suggérant des zones d'intérêt potentiel par détection de changements. Pour cela, nous effectuons une modélisation tridimensionnelle des apparences observées dans les vidéos de référence. Cette modélisation permet ensuite d'effectuer une détection en ligne des changements significatifs dans une nouvelle vidéo, en identifiant les déviations d'apparence par rapport aux modèles de référence. Des techniques spécifiques ont également été proposées pour effectuer l'estimation des paramètres d'acquisition ainsi que l'atténuation des effets de l'illumination. De plus, nous avons développé plusieurs techniques de consolidation permettant d'exploiter la connaissance a priori relative aux changements à détecter. L'intérêt et les bonnes performances de notre approche a été minutieusement démontré à l'aide de données réelles et synthétiques<br>Business activities based on the use of video data have developed at a dazzling speed these last few years: not only has the market of some of these activities widely expanded (video-surveillance) but the operational applications have also greatly diversified (natural resources monitoring, intelligence etc). However, nowadays, the volume of generated data has become overwhelming and the efficiency of these activities is now limited by the cost and the time required by the human interpretation of this video data. Automatic analysis of video streams has hence become a critical problem for numerous applications. The semi-autmoatic approach developed in this thesis focuses more specifically on the automatic analysis of aerial videos and enables assisting the image analyst in his task by suggesting areas of potential interest identified using change detection. For that purpose, our approach proceeds to a tridimensional modeling of the appearances observed in the reference videos. Such a modeling then enables the online detection of significant changes in a new video, by identifying appearance deviations with respect to the reference models. Specific techniques have also been developed to estimate the acquisition parameters and to attenuate illumination effects. Moreover, we developed several consolidation techniques making use of a priori knowledge related to targeted changes, in order to improve detection accuracy. The interest and good performance of our change detection approach has been carefully demonstrated using both real and synthetical data
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Faenza, L. "Analysis of the spatio-temporal distribution of large earthquakes." Thesis, 2005. http://hdl.handle.net/2122/3160.
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The investigation on the spatio-temporal distribution of large earthquakes is still a controversial issue in geophysics and many works in scientific literature have been devoted to this topic. The importance of understanding the statistical distribution of large events is aimed not only to extract information on the physics of the earthquakes occurrence process, but also to make reliable earthquake forecasting. As far as theoretical aspects are concerned, a satisfactory modelling may allow, at least in principle, to test a variety of hypotheses, such as the presence of any regularity in time, and the in uence of di erent tectonic/physical factors that regulate the spatial occurrence of earthquakes. At the same time, a reliable earthquake forecasting has undoubtedly a huge social impact because it may mitigate the seismic risk.<br>Universita' degli Studi di Bologna
Istituto Nazionale di Geofisica e Vulcanologia<br>Unpublished<br>3.1. Fisica dei terremoti<br>open
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Wen, Li-Ting, and 文莉婷. "Two-Person Interaction Recognition Based on Spatio-Temporal Interest Points for Depth Videos." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/83096381012307395512.
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碩士<br>元智大學<br>資訊工程學系<br>104<br>Recognizing human action has received considerable attention in computer vision research. Advances in the development of depth sensors and the technology of multimedia retrieval facilitate the applications of human action recognition based on depth images, including intelligent video surveillance, video retrieval, and human-computer interaction. Although numerous human action recognition methods have been proposed, most methods focus on single person action rather than two-person interaction. However, detecting high-level behavioral interaction between two people can facilitate social interaction interpretation, for example identification of conversation content, detection of violent activities in smart surveillance, and detection of presentation, discussions or taking notes in work meeting.
Most methods analyze human actions in depth videos using skeleton joints, provided by Microsoft, which may be less stable on fast and complex motions and occlusions, in particular when a large amount of body parts of two persons overlap. The proposed method extracts histograms of oriented gradient (HOG) and optical flow (HOF) for spatio-temporal interest points (STIPs) directly from depth videos to alleviate the problem. Matches (or corresponds) STIPs between two depth videos using the nearest neighbor rule in terms of HOG_HOF. A matching is regarded valid only if the matching consistency is satisfied. Matching distance is then computed according to the degree of similarity among valid matching pairs. The matching distances and number of matching pairs are then used to achieve interaction recognition. The proposed method is applied to the public SBU two-person interaction dataset. The experimental results demonstrate the effectiveness of our method.
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Xin, Xiaohong. "An exploratory data analysis approach for land use-transportation interaction the design and implementation of Transland spatio-temporal data model /." 2003. http://etd.utk.edu/2003/XinXiaohong.pdf.
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Thesis (Ph. D.)--University of Tennessee, Knoxville, 2003.<br>Title from title page screen (viewed Nov. 11, 2003). Thesis advisor: Shih-Lung Shaw. Document formatted into pages (xiii, 171 p. : ill. (some col.), col. maps). Vita. Includes bibliographical references (p. 136-147).
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Sklair, Nathan. "Spatio-Temporal Interactions in Immediate Serial Recall." Thesis, 2007. http://hdl.handle.net/1974/875.
Full textAbstract:
In an immediate serial recall task, participants are asked to recall lists of items in order. In the Hebb repeating-list variant of the task, subjects are read a series of lists, and every third list is repeated. Performance improves across repetitions but is stable for the non-repeated trials. The repetition advantage—the increased accuracy for the repeated list—is known as the Hebb effect.
Several models have been advanced to explain how participants order successive items, but how participants take advantage of the repetition has largely been ignored. Although the task is usually discussed in terms of recall of verbal items, the Hebb effect has been observed with sequences of visuo-spatial positions.
The present work assesses whether immediate serial recall of verbal material benefits
from visuo-spatial context. Sequences of letters were presented in different spatial positions in a visual version of the Hebb task. Presenting lists in random spatial positions on the periphery of an
imaginary circle did not boost performance, but if the sequence was predictable, overall accuracy increased. The spatial path of successive items influenced the Hebb effect. When the distance between successive positions was minimized, participants were able to exploit the repetition early
in practice. The results deny an account based on item distinctiveness. I discuss the results in terms of contemporary models of ISR.<br>Thesis (Master, Psychology) -- Queen's University, 2007-10-03 13:01:00.716
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Chou, Sheng-Ting, and 周昇廷. "Interactive Object Extraction Based on Spatio-temporal Color Coherence." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/44205083086998865687.
Full textAbstract:
碩士<br>國立中正大學<br>資訊工程所<br>96<br>We propose an integrated tracking system for applications which need more precise segmentation of target. The main tracking mechanism is accomplished by two trackers. The first tracker performs tracking by Adaboost on pixel-wise seed features; it can provide more detailed segmentation of target and combines with mean shift algorithm to track target in next frame. The second tracker achieves tracking by backward region tracking and uses temporal coherence to provide compensations to the short the first tracker. By confidence measure, the two trackers combine together and regions are labeled as foreground, background or uncertain. These uncertain regions are judged by spatial coherence. We also implement a tool which allows users to refine the result manually. Users can easily interact with frames which are probably in occlusion or perform poorly due to some complex situation.
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Lai, Mao-Wei, and 賴茂濰. "STOCPN: Spatio-Temporal Synchronization Model for Interactive Multimedia Document." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/49469814820663786035.
Full textAbstract:
碩士<br>國立暨南國際大學<br>資訊工程學系<br>90<br>Multimedia document objects with synchronized temporal and spatial presentation features have been widely used in numerous application areas such as e-learning and entertainment. Without interactive features, document presentation is just a fancy slide show with different media objects involved. User interactions in presentation time and/or layout would affect the corresponding temporal and/or spatial relations of involved objects. How to keep them resynchronized after user interaction is an important issue. This thesis addresses this issue and proposes an interactive multimedia synchronization model named Spatio-Temporal Object Composition Petri Net (STOCPN), which is based on OCPN with event-driven arcs extension, for maintaining the spatial and temporal relations of involved media objects in an interactive multimedia document. The proposed model has been applied into the core synchronization implementation in Web-based Multimedia Synchronized Lecture (WSML) system to assist students of the National Chi-Nan University in Taiwan to learn foreign language via web.
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Buckhout, Nathan. "Spatio-Temporal Factors Affecting Human-Black Bear Interactions in Great Smoky Mountains National Park." 2014. https://scholarworks.umass.edu/masters_theses_2/73.
Full textAbstract:
Wildlife managers use models to aid in predicting high risk areas for human and black bear (Ursus americanus) interactions (HBI). These tools help managers implement management strategies to minimize HBI. Over 3,000 incidents of HBI were compiled from management reports at Great Smoky Mountains National Park (GSMNP) during 1998-2011, a park with 9-10.2 million visitors per year and a black bear population of about 1,600 bears.
We used data from bear management reports along with annual visitor use, mast and bear abundance data to develop a series of generalized linear models to assess the spatial and temporal factors affecting HBI. Although HBI occurred throughout the GSMNP, 50% of all HBI occurred in five areas. The best predictor variables of HBI across four subsets of models included interaction between mast production and number of park visitors, month, vegetation cover, visitor activity, and bear abundance. Although there was not a clear relationship between visitor use and mast abundance, the number of park visitors was always relatively high and HBI increased substantially in poor mast years. HBI was more frequent during summer months when park visitation rates and more people and food were present overnight in frontcountry and backcountry camping areas. Over 43% of HBI in hemlock forests were serious. Bear abundance data were not a strong predictor of HBI, and bear bait stations may not provide a sensitive index to bear abundance.
GSMNP uses different strategies for managing HBI to protect visitors and bears. In 1991, bear proof waste disposal containers and food storage devices were placed in camping and picnic areas. In combination with aversive conditioning, HBI decreased in some areas of the park. We recommend that proactive bear management programs including education, enforcement of park regulations, and aggressive aversion conditioning of bears be implemented at the identified HBI high risk areas to provide a safer environment for both people and bears in GSMNP.
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Al, Alwan Bader. "Spatio-Temporal Characterization of Ligand-Receptor Interactions in Haematopoietic Stem Cell Rolling during Homing." Diss., 2018. http://hdl.handle.net/10754/629897.
Full textAbstract:
Researches on Hematopoietic Stem Cell (HSC) have been expanding that leads to an increase in our understanding of HSC normal behaviors and abnormal alterations. One of the most important issues in the research on HSCs is to understand the mechanism of the homing process of these cells to settle in their niche in the bone marrow and establish the production of various blood cell types after bone marrow transplantation. The cells first must come in contact with the endothelial cells. This contact is known as adhesion and occurs through a multi-step paradigm ending with transmigration to the bone marrow niche. The initial step of the homing, tethering and rolling of HSC, is mediated by P- and E-Selectins present on endothelial cell surface through their interactions with the ligands expressed on the surface of HSC. Thus, understanding the adhesion process and its contribution for efficient HSCs homing will have great impact on HSC therapy. The selectin – ligands interaction has been intensively studied using in vivo and in vitro approaches. However, the molecular mechanism involved by HSCs at single molecule level is poorly understood. Here in this study, a novel experimental method to unravel the
molecular mechanisms of the Selectin-ligands interactions in vitro at the single molecule level is developed by combining microfluidics, epi-fluorescence microscopy and live cells. In this work, the new single-molecule imaging technique enabled us to directly visualize the nanoscale spatiotemporal dynamics of the membrane protein-ligand interactions under conditions of shear stress acting on the cells at the molecular level in real time. Using this method, we revealed that selectin ligands on membrane-tethers and slings show unique spatiotemporal dynamics that is distinct from those on the cell body. We demonstrated that the membrane tethers are formed from single microvilli on the cells, which provides a mechanism to spatially localize selectin ligands, PSGL-1 and CD44 on the tethers and slings. We also demonstrated that the selectin ligands show fast diffusional motion along the tethers and slings compared with that on the cell body due to the detachment of cell membranes from actin cytoskeleton during the formation of the tethers. Our results suggest that the spatial confinement of the selectin ligands together with the fast scanning of a large area by the selectin ligands increase the efficiency of selectin-ligands interaction during the rolling, resulting in slow and stable rolling of the cell on selectin. Our findings contribute significantly to molecular level understanding of the initial step of HSCs. This single-molecule imaging technique that we developed in this study will find wide applications in the molecular-level studies on cell-cell interactions including cancer cell metastasis.
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Boieiro, Mário Rui Canelas. "Spatio-temporal variation in seed production in three Euphorbia species and the role of animals on seed fate." Doctoral thesis, 2012. http://hdl.handle.net/10400.13/562.
Full textAbstract:
Comparative studies on the reproductive biology of co-occurring related plant
species have provided valuable information for the interpretation of ecological and
evolutionary phenomena, with direct application in conservation management of plant populations. The aims of this thesis were to identify the causes of pre-dispersal
reproductive losses in three Euphorbia species (the Mediterranean E. characias and the narrow endemics E. pedroi and E. welwitschii) and evaluate the variation of their effects in time, space and between individuals and species. Furthermore, we intended to study elaiosomes’ fatty acid profiles for the three Euphorbia and assess the role played by the elaiosome in ant attraction. Finally, we aimed to identify the major seed dispersal agents for each Euphorbia species in each site and study differences in short term seed fate due
to differences in ant behaviour. The results indicated that intact seed production differed significantly between the three Euphorbia, mostly due to differences in cyathia production. Losses to pre-dispersal seed predators were proportionately larger for the endemic species which also suffered higher losses resulting in flower, fruit (in E. welwitschii) and seed abortion (in E. pedroi). The elaiosomes of E. pedroi are poor in fatty acids and for this reason seeds of this species were removed in lower proportion by mutualistic dispersers than those of their congeners, being more prone to seed predation.
Two larger ant species – Aphaenogaster senilis and Formica subrufa – were responsible for a larger percentage of removals with seeds being transported at larger distances and being discarded in the vicinity of their nests following elaiosome removal. Our results highlight the role of insect-plant interactions as major determinants of seed survival for the three study plants and call for the need to include more information on insect-plant
interactions in plant conservation programmes.<br>Fundação para a Ciência e Tecnologia