Tesi sul tema "Spectroscopie à haute résolution spatio-temporelle"
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Blanc, Ambre. "Dynamique quantique dissipative dans les systèmes excitoniques auto-assemblés". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0133.
The goal of this project is to develop theoretical models to allow the study of long-range energy transfers in self-assembled biological systems. We will focus on phenanthrene/pyrene π-stacks embedded in a DNA scaffold. The choice of these specific systems is motivated by recent time-resolved spectroscopic experiments, which revealed the important role of the excitonic transfer mechanism. Phenanthrene-based π stacks have demonstrated an exceptional capacity for coherent excitonic transport up to 150nm. At this scale, the transport is due to a mixed mechanism : on the one hand to the delocalization of the exciton on several phenanthrene units, and on the other hand to incoherent jumps between neighboring units. The addition of a pyrene unit also allows the construction of a donor-acceptor system, whose terminal pyrene unit is quenched by nanosecond-scale fluorescence and the photo-excitation leading the system out of equilibrium, exciton transport and fluorescence processes are in competition with the energy relaxation. A preliminary study was carried out on the smallest model produced experimentally, a dimer of phenanthrene and pyrene, characterizing an end of an experimental chain. Temporal competition between photo-induced processes was evaluated by a dynamic study. It allowed the simulation of time-resolved fluorescence spectra, related to the dynamics observed experimentally. Then, theoretical observations were corroborated by experimental hypotheses. At short times after the excitation of a phenanthrene, processes of anti-Kasha and Kasha fluorescence on it were put forward. At longer time scales, a decrease in the population of phenanthrene was observed in favor of the population of pyrene. A strong Kasha fluorescence signal was observed for this fragment. On the other hand, the limits of the model were questioned. Indeed, the experiment poses the hypothesis of a delocalized and coherent behavior at the level of the pyrene. However, it is a local and incoherent mechanism that dominates theoretical observations at the end of the chain. In order to facilitate the interpretation of coherent mechanisms in larger systems, the search for a local characterization of the excitations was carried out. A diabatization method from delocalized electronic states has then been developed. A localization measure has been developed, reporting the effectiveness of the method. To complete the local description of the effect of vibronic couplings, a perturbative study made it possible to determine the dominant vibrations in the vibrational relaxation within the system. Skeletal vibrations of all the atoms of the same fragment showed an important contribution to the acceleration of the dissipation towards the ground state. These were coupled to the local electronic degrees of freedom in order to complete the local vibronic basis. An excitonic Hamiltonian was then parameterized and composed of blocks in this local and minimal basis suitable for the description of intramolecular and intermolecular transitions. The study of reduced stacks of phenanthrenes and pyrenes has made it possible to create a theoretical model for the study of energy transfer in chain polymers. Its efficiency and its relevance have been tested with calculations of coherent dynamics of excitons in a local vibronic base. It includes the preliminary tools for the study of exciton dynamics in extended stacks. In particular, the excitonic description of the Hamiltonian facilitates its extension on a longer scale. This can also be introduced into a more realistic study of dissipative quantum dynamics. It allows to include various effects leading to decoherence and energy loss, likely to impact energy transfers
Dhokkar, Sonia. "Etude des phénomènes thermiques dans un MOSFET en commutation : mesure de la température à haute résolution spatiale et temporelle par radiométrie proche infrarouge et confrontation à un modèle thermique". Poitiers, 2008. http://www.theses.fr/2008POIT2305.
Beaudoin, Normand. "Méthode mathématique et numérique de haute précision pour le calcul des transformées de Fourier, intégrales, dérivées et polynômes splines de tout ordre ; Déconvolution par transformée de Fourier et spectroscopie photoacoustique à résolution temporelle". Thèse, Université du Québec à Trois-Rivières, 1999. http://depot-e.uqtr.ca/6708/1/000659516.pdf.
Le, Men Camille. "Segmentation Spatio-temporelle d'une séquence d'images satellitaires à haute résolution". Phd thesis, Ecole nationale supérieure des telecommunications - ENST, 2009. http://pastel.archives-ouvertes.fr/pastel-00658159.
Law-Hine, Didier. "Sonder la cinétique d'auto-assemblage de nano-capsules virales à haute résolution spatio-temporelle". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS072/document.
Viral assembly is an intriguing topic of biophysics that can be studied using concepts of soft matter physics. Although huge efforts have been made to synthesize hybrid or non-hybrid supramolecular assemblies with viral proteins, the fundamental mechanisms of self-assembly are yet poorly understood. In particular, the kinetic pathway in which the proteins interact with the genome to form highly symmetrical monodisperse architectures are not completely solved.In the first part of this thesis, the Time-Resolved Small-Angle X-Ray Scattering (TR-SAXS) technique is used to probe the kinetics of both self-assembly and disassembly of empty capsids built up from the proteins of the Cowpea Chlorotic Mottle Virus (CCMV). Chemical kinetics models coupled with concepts of SAXS theory are devised in order to extract information about the nature of the reaction intermediates, their structure and their typical lifetime. The encapsulation of ssRNA with CCMV capsid proteins is also examined in this thesis. At neutral pH where the capsid proteins do not spontaneously assemble in vitro into empty spherical capsids, electron microscopy images show that there is a non-negligible population of disordered nucleoprotein complexes that coexist with well-formed spherical viruses. Additionally, TR-SAXS kinetic data suggest that the protein-nucleic acid assembly undergoes a structural reorganization in which the capsid proteins make the nucleoprotein complexes more compact as they simultaneously bind the RNA. Upon acidification, the particles are well-formed viruses as suggested by electron microscopy images. These findings suggest that the encapsulation of RNA into well-formed viruses is likely a two-step assembly with a binding step and an acidification step
Herrou, Glenn. "Résolution Spatio-temporelle Adaptative pour un Codage à Faible Complexité des Formats Vidéo Émergents". Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0020.
The definition of the latest Ultra-High Definition TV (UHDTV) standard aims to increase the user’s quality of experience by introducing new video signal features such as 4K and High Frame-Rate (HFR). However, these new features multiply by a factor 8 the amount of data to be processed before transmission to the end user.In addition to this new format, broadcasters and Over-The-Top (OTT) content providers have to encode videos in different formats and at different bitrates due to the wide variety of devices with heterogeneous video format and network capacities used by consumers.SHVC, the scalable extension of the latest video coding standard High Efficiency Video Coding (HEVC) is a promising solution to address these issues but its computationally demanding architecture reaches its limit with the encoding and decoding of the data-heavy newly introduced immersive video features of the UHDTV video format.The objective of this thesis is thus to investigate lightweight scalable encoding approaches based on the adaptation of the spatio-temporal resolution. The first part of this document proposes two pre-processing tools, respectively using polyphase and wavelet frame-based approaches, to achieve spatial scalability with a slight complexity overhead.Then, the second part of this thesis addresses the design of a more conventional dual-layer scalable architecture using an HEVC encoder in the Base Layer (BL) for backward compatibility and a proposed low-complexity encoder, based on the local adaptation of the spatial resolution, for the Enhancement Layer (EL).Finally, the last part of this thesis investigates spatiotemporal resolution adaptation. A variable frame-rate algorithm is first proposed as pre-processing. This solution has been designed to locally and dynamically detect the lowest frame-rate that does not introduce visible motion artifacts. The proposed variable frame-rate and adaptive spatial resolution algorithms are then combined to offer a lightweight scalable coding of 4K HFR video contents
Touhami, Younès. "Identification spatio-temporelle d'une source de chaleur dans un milieu diffusif par résolution d'un problème inverse". Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11059.
Audugé, Nicolas. "Imagerie à haute résolution spatio-temporelle de la dynamique chromatinienne en cellules vivantes : étude de l'interaction entre le bromodomaine et l'histone H4 acétylée". Paris 7, 2009. http://www.theses.fr/2009PA077248.
Fluorescence microscopy is rapidly evolving and the development of novel techniques offers new prospects in thé study of the cellular processes. The possibility of following protein interactions in real-time and in living cells leads to a more dynamic vision of the molecular mechanisms occurring throughout the life of a cell. The purpose of my thesis was to study the interaction between the acetylated histone H4 and the double bromodomain of protein TAFII250. This interaction was analyzed by a technique of fluorescence microscopy, FLIM by FRET, developed within the laboratory and making possible to obtain in real-time, with a high space and time resolution, a follow-up of the interaction in living cells. This interaction, dependent on the histone H4 acetylation rate, seems to be very dynamic and to be carried out in a very localized way on the chromatin, on the domains of 0,7}in of diameter. Similarly, the analysis of the fluorescence of the protein EGFP-H4 reveals fluctuations of the fluorescence lifetime of this fluorophore. Further analyses strongly argue that these fluctuations are due to the variations of the microenvironment of the EGFP and thus reflecting the variations of the supra-nucleosomal state of chromatin. Also, we show that the interaction between the double bromodomain of TAFII250 and the histone H4 is driven by these fluctuations of the supra-nucleosomal state. In a more general way, we propose that these fluctuations would modulate the accessibility of chromatin to the protein factors
Servera-Vives, Gabriel. "Dynamique holocène du paysage et mobilités des pratiques territoriales au mont Lozère (Massif central, France) : Approche paléoenvironnementale multi-indicateurs à haute résolution spatio-temporelle". Thesis, Limoges, 2014. http://www.theses.fr/2014LIMO0031/document.
Five sedimentary sequences have been studied in the Mont Lozère with the aim to reconstruct the landscape dynamics and the land-use through the longue durée. The use of a multi-proxy analysis has allowed us both to identify distinct rhythms of human-induced landscape shift and to establish the local/regional extent of these changes. The use of high spatial, chronological and analytical resolution has enabled a correct integration of the results of this research with those supplied by the PCR-Mont Lozère project. As a result, a series of land-uses in a mountain environment from the Neolithic to present time has been proposed. A long history of socio-environmental interactions in Mont-Lozère is evidenced. A first shepherding phase in Early Neolithic (4550-4400 cal BC) has been evidenced. During Late Neolithic pastoral practices and related slash-and-burn strategies attain its highest activity. In the Iron Age Period a noticeable deforestation of both foothills and higher environments takes place as a consequence of the overall increase farming and metallurgical activities. Forest clearances increase even more during High-Medieval times, at the same time that farming activities reinforce. During the Middle Ages a more complex and diversified land-use system, including farming, metallurgy, mining and charcoal production, is recorded. The development of farming activities in the Late Medieval resulted in a more evident forest clearance of the Massif. This area remained unchanged until the 19th century, when the decay of agriculture and shepherding occurs and forest replanting in Mont Lozère is recorded. The history of highland herb communities of Nardus stricta correctly matches the main phases of land-use and underlines the key-role of farming in the genesis and evolution of this cultural landscape
Se han estudiado cinco secuencias sedimentarias en el Mont Lozère con el objetivo de reconstruir la dinámica paisajística y los usos del suelo en la longue durée. La utilización de un análisis multiproxy ha permitido determinar los principales ritmos de antropización y establecer su carácter regional y/o local. La alta resolución espacial, cronológica y analítica hapermitido la integración de resultados con aquellos obtenidos en el marco del PCR-Mont Lozère y proponer los usos de la montaña que han modelado el paisaje cultural desde el Neolítico hasta la actualidad. Se ha evidenciado una larga historia de las interacciones socioambientales en el Mont Lozère, con una primera fase de carácter agropastoral en el Neolítico Antiguo, en ca. 4550-4400 cal BC. El Neolítico Final es una fase de marcado impacto agropastoral en la que se generalizan las quemas para abrir claros en el bosque. En la Edad del Hierro se inicia una marcada deforestación en el piedemonte y los espacios de altitud, coincidiendo con un desarrollo agropastoral y metalúrgico. En el periodo altomedieval se amplifican las deforestaciones coincidiendo con un marcado incremento de las actividades agropastorales. En la Plena Edad Media se evidencia un sistema diversificado que implica metalurgia, agricultura, pastoreo, minería y carboneo. El desarrollo agropastoral de la Baja Edad Media supone una marcada deforestación en el macizo que se extiende hasta mitad del s. XIX, momento en que se inicia el declive del agropastoralismo y empiezan las reforestaciones en el Mont Lozère. La historia de las formaciones herbosas con Nardus stricta de los espacios somitales sigue estas principales fases de antropización y revela el papel clave del agropastoralismo en la génesis y evolución de este paisaje cultural
André, Christophe. "Développement d'une méthode de mesure de fluctuations de concentration par spectroscopie de fluorescence à hautes résolutions spatiale et temporelle". Vandoeuvre-les-Nancy, INPL, 1991. http://www.theses.fr/1991INPL079N.
Aquilanti, Giuliana. "Challenges pour la spectroscopie d'absorption X en dispersion d'énergie à l'ESRF: résolution temporelle à la microseconde et pressions au Megabar". Phd thesis, Université de Grenoble, 2002. http://tel.archives-ouvertes.fr/tel-00828730.
Galloy-Gimenez, Lucie. "Réalisation d'une cellule électroacoustique pulsée à haute résolution spatiale en vue de l'étude spatio-temporelle de la répartition de la charge d'espace dans les diélectriques spatiaux soumis à un environnement chargeant". Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2516/.
Dielectric materials are frequently used in satellite structures as thermal blankets. Various aspects of the space environment can cause orbit satellite anomalies. One of these aspects is charge accumulation due to the flux of space charged particles. To get a better control of the discharge it is necessary to clarify the nature and the time evolution of position and quantity of stored space charges and to understand the dynamics of the charge transport in solid dielectrics used in outer space. Dielectrics materials for space application are typically thin, less than 50 µm. Therefore; the pulsed electro-acoustic - PEA - method, which is used to recover charges within this type of material, is no longer sufficiently precise, i. E. The spatial resolution is on the order of ten µm. We developed an electrical model of the PEA cell and we note that the piezoelectric losses and impedance matching between the different materials of the PEA cell have a significant influence on the quality of the transducer output voltage. Then, we present a high resolution PEA prototype, used to perform first ever; to our knowledge, measurements on the 50 µm thick PTFE with a special resolution of 1µm
Tran, Thi Dong Binh. "Croissance spatio-temporelle de la ville de Da Nang, Vietnam entre 1990 et 2001 : Apport de la télédétection et de l'analyse fractale". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. http://www.theses.fr/2007STR1GE05.
Servera, Vives Gabriel. "Evolución del paisaje holoceno y movilidad de las prácticas humanas en el Mont Lozère (Macizo Central, Francia): estudio paleoambiental multi-proxy a alta resolución espaciotemporal = Dynamique holocène du paysage et mobilités des pratiques territoriales au mont Lozère (Massif central, France) : approche paléoenvironnementale multi-indicateurs à haute résolution spatio-temporelle". Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/671884.
Five sedimentary sequences have been studied in the Mont Lozère with the aim to reconstruct the landscape dynamics and the land-use through the longue durée. The use of a multi-proxy analysis has allowed us both to identify distinct rhythms of human-induced landscape shift and to establish the local/regional extent of these changes. The use of high spatial, chronological and analytical resolution has enabled a correct integration of the results of this research with those supplied by the PCR-Mont Lozère project. As a result, a series of land-uses in a mountain environment from the Neolithic to present time has been proposed. A long history of socio-environmental interactions in Mont-Lozère is evidenced. A first shepherding phase in Early Neolithic (4550-4400 cal BC) has been evidenced. During Late Neolithic pastoral practices and related slash-and-burn strategies attain its highest activity. In the Iron Age Period a noticeable deforestation of both foothills and higher environments takes place as a consequence of the overall increase farming and metallurgical activities. Forest clearances increase even more during High-Medieval times, at the same time that farming activities reinforce. During the Middle Ages a more complex and diversified land-use system, including farming, metallurgy, mining and charcoal production, is recorded. The development of farming activities in the Late Medieval resulted in a more evident forest clearance of the Massif. This area remained unchanged until the 19th century, when the decay of agriculture and shepherding occurs and forest replanting in Mont Lozère is recorded. The history of highland herb communities of Nardus stricta correctly matches the main phases of land-use and underlines the key-role of farming in the genesis and evolution of this cultural landscape.
COSQUER, Ronan. "Conception d'un sondeur de canal MIMO - Caractérisation du canal de propagation d'un point de vue directionnel et doublement directionnel". Phd thesis, INSA de Rennes, 2004. http://tel.archives-ouvertes.fr/tel-00007560.
Louchart, Arnaud. "Dynamique spatio-temporelle des communautés phytoplanctoniques côtières et de leurs caractéristiques intrinsèques, à partir d'une approche automatisée à haute résolution Phytoplankton distribution from Western to Central English Channel, revealed by automated flow cytometry during the summer-fall transition Spatial niches of phytoplankton functional groups assessed during a spring bloom development in two temperate coastal seas Untangling the vertical distribution of phytoplankton groups along a salinity gradient through the Baltic Sea and the Skagerrak-Kattegat straits". Thesis, Littoral, 2020. http://www.theses.fr/2020DUNK0556.
In coastal ecosystems, phytoplankton composition, distribution and dynamics are strongly influenced by spatial and temporal variations of hydrological structures and biogeochemical parameters, consequences of natural and anthropogenic pressures. Reference monitoring, due to its low spatial and temporal resolution, may fail to detect key events as the initiation and end of phytoplankton outbursts or harmful algal blooms (HABs). By increasing the spatial and/or temporal resolution as well as completing taxonomical counting by investigating the phytoplankton whole size spectra, the use of automated sensors may allow contributing to a better understanding of the distribution and dynamics of this major player in biogeochemichal cycles, at the basis of most foof webs. This thesis consists in studying the characteristics of phytoplankton functional groups defined from their optical properties at the single-cell level, in relation to spatio-temporal variability encountered in contrasting marginal seas, applying the pulse shape-recording automated flow cytometry. This functional classification reflects the diversity of particles according to morphological and physiological properties. First of all, the distribution of phytoplankton groups and their traits where explored in the Western and Central English Channel during the summer period. Most groups formed patches of abundance and biomass near the Ushant front and were structured at the sub-mesoscale. Secondly, phytoplankton functional groups dynamics was characterized in the Eastern English Channel and Southern North Sea during the development period of diatoms and Phaeocystis globosa spring groups, by calculating LCBD and SCBD, wich allowed the observation of spatial segregation between phytoplankton groups. Their distribution was explained by the niche parameters (marginality and tolerance). Finally, the vertical distribution of phytoplankton functional groups in a salinity gradient was addressed in the Baltic Sea, in relation to the biogeochemical properties of the water masses and the characteristics of each PFGs. The variations of the traits are thus stand out as the best predictors of the horizontal and vertical distribution of phytoplankton groups with the respect to niche parameters and spatial descriptors (dispersion, physical and biological parameters). The functional approach, derived from phytoplankton optical properties addressed by automated flow cytometry, coupled to the niche analysis, make it possible to better explain and predict community responses to environmental gradients, such responses being detected in parallel by diversity indices. This work benefited from the support of local (MARCO State-Region Plan Contract), national (CNRS-MTES convention) and international European H2020 JERICO-NEXT projects
Barthélemy, Olivier. "Caractérisation d'un plasma d'aluminium créé par interaction laser-matière à bas flux sous environnement atmosphérique". Thèse, 2004. http://hdl.handle.net/1866/17330.