Dissertationen zum Thema „Photo-Dynamics“
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1
Kadi, Malin. „Ultrafast Photo-induced Reaction Dynamics of Small Molecules“. Doctoral thesis, Uppsala University, Department of Physical Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3597.
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The main focus of this thesis is the investigation of the dissociation dynamics of aryl halides using femtosecond pump-probe spectroscopy. In the monohalogenated aryl halides, iodo-, bromo- and chlorobenzene, the rate of dissociation following excitation at 266 nm in the gas phase increased with increasing mass of the halogen atom. This process was assigned to predissociation of the initially excited singlet (π, π*) state via a repulsive triplet (n, σ*) state due to spin-orbit interaction. In addition to the predissociative mechanism, a direct dissociation channel was observed in iodobenzene. The rate of the predissociation in bromobenzene was found to be faster in the condensed phase than in the gas phase, which can be explained by solvent-induced symmetry perturbations. Ab initio calculations of the potential energy surfaces of the ground state and several low lying excited states in bromobenzene have been performed in order to verify the suggested mechanism. Substituting one of the hydrogen atoms in bromobenzene affected the predissociation rate significantly. In o-, m- and p-dibromobenzene the predissociation rate increased with decreasing distance between the bromine atoms in accordance with an increased spin-orbit interaction introduced by the bromine substituent. The fastest predissociation rate was observed in 1,3,5-tribromobenzene. With chlorine and fluorine substitution, inductive and conjugative effects were found to be of importance. In the o- and m-isomers of the dihalogenated aryl halides, an additional faster dissociation channel was observed. Guided by ab initio calculations of the potential energy surfaces in the dibromobenzene isomers, we ascribed the fast dissociation pathway to predissociation of an initially excited triplet state. Upon methyl group substitution in bromobenzene, the decreased lifetime of the initially excited state was attributed to an incresaed density of coupled states.
Another system which has been studied in the condensed phase is diiodomethane. Using Car-Parrinello molecular dynamics simulations we observed a prompt dissociation and subsequent recombination to the isomer, iso-diiodomethane, in acetonitrile solution.
Vibrational wavepacket dynamics in the C (1Σ+) state of NaK were studied using a direct ionization probing scheme. A simple analytical expression for the pump-probe signal was developed in order to see what factors that govern direct ionization of the vibrational wavepacket. Our experimental data was consistent with a photoionization transition dipole moment that varies with internuclear distance.
2
Eitoku, Takeshi. „Photo-induced conformational dynamics of phototropin LOV domains“. 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136904.
3
Han, Alex Chao. „Coherence and control in photo-molecular wave packet dynamics“. Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53991.
Annotation:
Wave-mechanical phenomena such as resonance and interference, in both light and matter, are central to the principles of quantum coherent control over molecular processes. Focusing on the dynamical aspects, this dissertation is a compilation of studies on the interaction physics involving wave packets in molecules, the driving light field, and the underlying coherence and control. In each work, we will demonstrate interesting correlations between the properties of a carefully designed excitation light field and desirable outcomes of the molecules quantum dynamics. We will analyze the dynamical effect of a Feshbach resonance in the adiabatic Raman photoassociation for ultracold diatomic molecule formation from ultracold atoms. A narrow resonance is shown to be able to increase the effective number of collisions, in an ultracold atomic gas, that are available for photoassociation. This results in an optimal resonance width much smaller than the atomic collision energy bandwidth, due to the balance between the effective collision rate and single-collision transfer probability. Next, we demonstrate the linear molecular response to high-intensity, broadband, shaped optical fields. We show that this originates from interferences based on intra-pulse Raman excitations, and thus response linearity is not unique to the first-order perturbative limit and can not be used to infer the strength of the field. In the last study, we simulate the stochastic vibrational wave packet and dissociation-flux dynamics in a molecule excited by light with temporal and spectral incoherent properties. Between this case and that using a coherent pulse with the same spectral profile, we compare the vibrational wave functions and the loss of electronic and vibrational coherence, and demonstrate the qualitative difference between coherently and incoherently driven dynamics in molecules.Science, Faculty of
Physics and Astronomy, Department of
Graduate
4
Suddick, Emma C. „Nitrogen photo-chemistry and the dynamics of CDOM in aquatic environments“. Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485377.
Annotation:
Photochemical ammonium production and photo-bleaching of chromophoric dissolved organic matter (CDOM) kinetics were studied in a variety of aquatic environments including freshwater samples of peatland origin, Caithness, a Tyne Estuary (NE, U.K.) estuary and the Iberian Sea. The main aims of the study were to assess seasonal variability within the peatland catchments, in conjunction with a study of regional and geographical variability of dissolved organic matter (DOM) and ammonium photo-production. Samples collected from a variety of aqueous environments covered the CDaM .absofPtion coefficient at 350 nm (a350) range 0.3 to 69.0 m-I. Selected, filtered samples (n=21) were exposed to natural and artificial light, in order to study ~+ photo-production CDaM photo-bleaching. The photo-chemical degradation of CDaM, as indicated by decreases in a350 over time, also led to increases in the spectral slope of sample absorbance over the wavelength range 290-350 nm, and losses of total fluorescence intensity. In addition we observed hypsochromic shifts of long-wave, humic-like fluorescence (fluorophore A). Photo-chemical ammonium release was observed in 19 of the total 21 irradiation experiments. However the kinetics of ammonium production were complex with 4 of the 21 samples showing a near-linear increase in NH/ concentration while other samples showed an initial lag phase, followed by production and then a decline in NH/ concentrations. In order to assess possible impacts of ~+ release on N balance we estimated NH4+ photoproduction potentials from concentration differences between the initial values and maximum ~+ values divided by irradiation time (i1t). Thus obtained ~+ photo-production potentials between sites ranged from 0 to 3.57 JIM r1 h-I (mean ± stdev 0.7) under solar noon irradiance levels. Using calculated daily sky irradiance and seasonal correction factors, annual depth integrated ~+ photo-production rates were estimated, ranging from 0.06 to 8.05 JIMNm-2 yrI( mean ± stdev 2.73). The photo-chemical production ofNH/ indicates that photo-chemically induced nitrogen release could potentially be an important source of biologically labile nitrogen to aquatic ecosystems, with severe impacts upon the biogeochemistry and nutrient limitation of these environments when compared to N-reservoir size and other N fluxes. However, compared to N deposition photo-ammonification is not a major source ofN. Key words: Dissolved organic matter, chromophoric dissolved organic matter, photoammonification, peatlands, estuaries, marine, and fluorescence.
5
Chavez, Cervantes Mariana [Verfasser], und Isabella [Akademischer Betreuer] Gierz. „Photo-Carrier Dynamics and Photo-Induced Melting of Charge Density Waves in Indium Wires / Mariana Chavez Cervantes ; Betreuer: Isabella Gierz“. Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1212585143/34.
6
Agathangelou, Damianos. „Anabaena Sensory Rhodopsin : effect of mutations on the ultrafast photo-isomerization dynamics“. Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE001/document.
Annotation:
ASR, est une protéine photo réceptrice qui lie la base protonée de la rétine de Schiff dans deux conformations de l'état fondamental. La protéine particulière consiste en un système modèle dans lequel I'effet de l'environnement protéique sur la dynamique d'isomérisation des deux isomères peut être étudié. Dans cette thèse, une étude approfondie sur les protéines mutées ponctuellement est présentée, où la variable est l'environnement protéique. Les résultats montrent des différences significatives entre les durées de vie des états excités des deux isomères et les durées de vie plus courtes ou plus longues commentées en termes de mélange électronique Sl/S2. En complément, le développement expérimental d'un spectromètre à absorption transitoire (T.A) et d'un dispositif de spectroscopie électronique bidimensionnelle (2DES) fonctionnant respectivement dans les domaines spectral NIR et UV-Vis. Avec cette configuration, deux impulsions colinéaires à verrouillage de phase d'une durée inférieure à 10fs sont générées, où. la précision interférométrique sur le contrôle du retard entre les deux impulsions de pompe permet d'effectuer des mesures 2DESASR, is a photoreceptor protein that binds the protonated Schiff base of retinal in two ground state conformations. The particular protein consists a model system where the effect of the protein environment on the isomerization dynamics of the two isomers can be investigated. In this thesis an extended study on point mutated proteins is presented where the variable is the protein environment. The results show significant differences between the two isomers excited state lifetimes with the shorter or longer lifetimes commented in terms of Sl/S2 electronic mixing. Supplementary, the experimental development of a Transient absorption spectrometer (T.A) and a Two-dimensional electronic spectroscopy setup (2DES) operating in the NIR and UV-Vis spectral range respectively are described. The 2DES spectrometer is based on translating wedges made out of birefringent material producing two collinear phase-locked pulses with sub-I Ofs duration. The interferometric precision on controlling the delay between the two pump pulses allows to perform 2DES measurements on systems absorbing in the 360-430 nm range allowing to resolve the excitation process spectrally
7
Perveaux, Aurelie. „Study of photo induce process by quantum chemistry and quantum dynamics methods“. Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS144/document.
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C’est dernières années, les progrès des techniques expérimentales combinées avec les simulations théoriques ont données un accès à l’étude et le contrôle des réactions photochimiques dans des systèmes moléculaires de grande taille. Ceci ouvre des portes à de nouvelles applications technologiques. Par exemple, les molécules de la famille du 3-hydroxychromone et de l’aminobenzonitrile sont des types de systèmes où les spectres de fluorescences vont présentés des différences importantes suivant l’environnement du système ou même suivant les substituants utilisés. Ce type de propriété est crucial dans le domaine des matériaux organique, afin de pouvoir comprendre et designer des matériaux qui présentent des propriétés optiques choisis tells que les marqueurs fluorescents dans le domaine médical par exemple.Notre stratégie pour étudier la réactivité photochimique est la suivante: *Explorer la surface d’énergie potentielle et optimiser les points spécifiques avec des calculs de chimie quantiques. Dans un premier temps, on a utilisé des méthodes CASSCF/CASPT2 et la méthode PCM pour décrire les effets de solvant. * Génération des surfaces d énergies potentielles exprimer sous la forme de fonctions analytiques des coordonnées nucléaires. * Résolution de l’équation de Schrödinger dépendant du temps pour les noyaux et pour tout les derges de libertés de la molécule. Cette étape est faite à l’aide de la méthode multilayer multiconfiguration time-dependent hartree (ML-MCTDH)Over the last decades, progress in experimental techniques combined with theoretical simulations has given access to studying and controlling the photochemical reactivity of large molecular systems with numerous technological applications. 3-hydroxychromone and aminobenzonitrile-like molecules are an example where different fluorescence patterns are observed, depending of the solvent or its substituents. Such properties are crucial in the field of organic materials to understand and design materials with specific optical properties such as fluorescent markers.Our strategy to study the photochemistry reactivity is summarised as follows: * Exploring the potential energy surfaces and optimising specific points with quantum chemistry calculations. In a first stage, these are run at the CASSCF/CASPT2 level of theory with a polarised extended basis set, and the solvent effect is described implicitly with the PCM model. * Generating the full dimension potential energy surfaces as analytical functions of the nuclear coordinates.* Solving the nuclear time-dependent Schrödinger equation for all the degrees of freedom. This is achieved with the multilayer Multi-Configuration Time-Dependent Hartree method (ML-MCTDH)
8
Burtt, Kelly D. „Computational studies of photo-induces isomerization dynamics in a model molecular motor system“. abstract and full text PDF (free order & download UNR users only), 2005. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3209954.
9
Wall, Simon. „Photo-induced dynamics in complex materials probed with femtosecond x-rays and few cycle optical pulses“. Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510258.
10
Pollum, Marvin. „Applying Fundamental Photochemistry to Drive Drug Development: The Photo-Dynamics and Reactions of Sulfur-Substituted Nucleic Acids“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1481287737895585.
11
Zhao, Yuan. „Identification and quantification studies on structures, dynamics and mechanism for thermal and photo-degradation products of β-carotene“. University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1323736801.
12
Behrmann, Caryn Ann. „Occurrence and group dynamics of Heaviside’s dolphins (Cephalorhynchus heavisidii) in Table Bay, Western Cape, South Africa“. Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/30835.
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Heaviside‟s dolphins, Cephalorhynchus heavisidii, are among the least known
cetaceans. They are endemic to the coastal waters along the west coast of southern
Africa. The occurrence, behaviour and group dynamics were investigated for these
dolphins in Table Bay, South Africa during the summer of 2008 and 2009. Markrecapture
photographic identification techniques, modelling techniques and
Geographical Information System (GIS) were used to analyse the data.
The dolphins were observed primarily in a well-defined 7 km2 area on the south side
of Table Bay along a 3 km east-west stretch of coast known as Granger Bay, and
within 2 km from shore. They used this area heterogeneously; for the array of
behaviours observed, all core areas (50 % kernels) were located in Granger Bay with
very little overlap of areas used for milling, socialising, resting and travelling.
Milling and socialising were exhibited more often than travelling and resting.
Foraging was never observed in areas close to shore, which supports earlier studies
suggesting that these dolphins forage primarily offshore.
Of the 95 identified individuals, 24.2 % of the individuals were seen only once and
73.7 % of the individuals were sighted less than five times while two individuals were
seen 11 times. Groups varied in size from one to 26 animals with a median of five
animals. Many of the potential dyads were never seen and those observed had
generally weak measure of association. The group structure appears highly dynamic,
with great lability in group sizes and membership, suggesting a fluid social system
with mostly weak inter-individual bonds. Individuals in Table Bay display low site
fidelity, at least in the short-term.
The observed pattern of area use and behavioural preferences indicate that coastal
management strategies should consider the ecological and behavioural needs of
Heaviside's dolphins to appropriately safeguard this species as a valuable component
of South African natural treasures and legally protected taxa. Further continuing
research is needed to build on this initial study to better understand the processes that
shape the population structure and group dynamics of Heaviside's dolphins, and to
provide further detail on habitat preferences and areas used, both in Table Bay and
environs.Dissertation (MSc)--University of Pretoria, 2011.
Zoology and Entomology
Unrestricted
13
Green, Travis Christopher. „Photo-induced charge carrier dynamics and self-organization in semiconductor and metallic nanocrystals : in between the bulk and individual molecules“. Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/30480.
14
Tomita, Takafumi. „Quantum Many-Body Dynamics of the Bose-Hubbard System with Artificial and Intrinsic Dissipation“. Kyoto University, 2019. http://hdl.handle.net/2433/242587.
15
Heiss, Gregor [Verfasser]. „Single-Molecule Microscopy Study of Nano-Systems: From synthetic photo-switchable nano-devices to the dynamics of naturally occurring transcription factors / Gregor Heiss“. München : Verlag Dr. Hut, 2012. http://d-nb.info/102029860X/34.
16
Barreau, Lou. „Étude de dynamiques de photoionisation résonante à l'aide d'impulsions attosecondes“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS511/document.
Annotation:
Cette thèse s’intéresse à la photo-ionisation de systèmes atomiques et moléculaires en phase gazeuse à l’aide d’harmoniques d’ordre élevé, un rayonnement cohérent dans le domaine de l’extrême ultraviolet (10-100 eV) sous la forme de trains d’impulsions attosecondes (1 as = 10-18 s). Dans un premier temps, les dynamiques électroniques au cours de l’auto-ionisation de gaz rares sont étudiées par interférométrie électronique. L’auto-ionisation résulte de l’interférence entre un chemin d’ionisation direct et un chemin résonant pour lequel l’atome reste transitoirement piégé dans un état excité.L’amplitude de la transition associée à ces processus est accessible via des expériences de photo-ionisation dans le domaine spectral (sur synchrotron par exemple), mais ce n’est pas le cas de la phase qui est pourtant essentielle à la compréhension de la dynamique électronique.Nous avons développé plusieurs méthodes interférométriques afin de mesurer la phase spectrale associée aux transitions électroniques vers des résonances de Fano dans les gaz rares.A partir des informations dans le domaine spectral, nous avons reconstruit pour la première fois la dynamique d'auto-ionisation ultra-rapide dans le domaine temporel et observé les interférences électroniques donnant lieu au profil de raie asymétrique. Dans un second temps, la photo-ionisation de molécules de NO est étudiée dans le référentiel moléculaire et utilisée comme un polarimètre afin de caractériser complètement l’état de polarisation du rayonnement harmonique, et en particulier de distinguer la partie du rayonnement polarisée circulairement d’une éventuelle partie dépolarisée. Nous présentons les résultats des mesures de polarimétrie moléculaire dans le cas de la génération d’harmoniques par un champ à deux couleurs polarisées circulairement en sens opposé. Ces études, complétées par des simulations numériques, permettent de proposer des conditions optimales de génération de rayonnement harmonique polarisé circulairement et contribuent à ouvrir la voie vers des études de dichroïsme circulaire ultrarapide dans la matièreIn this work, photoionzation of atomic and molecular species in the gas phase is investigated with high-harmonic radiation. In a first part, electronic dynamics in the autoionization process of rare gases in studied with electron interferometry. This method gives access to the spectral phase of the transition to the autoionizing state, and allows there construction of the entire autoionization dynamics. The ultrafast electronic dynamics, as well as the build-up of the celebrated asymmetric Fano profile, are observed experimentally for the first time. In a second part, photoionization of NO molecules in the molecular frame is used as a polarimeter to completeley characterize the polarization state of high-harmonics. In particular, this method can address the challenging disentanglement of the circular and unpolarized components of the light. The experimental results, completed by numerical simulations, allow defining optimal generation conditions of fully circularly-polarized harmonics for advanced studies of ultrafast dichroisms in matte
17
Masson, Antoine. „Réaction par transfert de charge métal-ligand femtochimie aux temps ultra-courts et spectroscopie de l'état de transition en gouttelette d'hélium“. Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00649169.
Annotation:
Cette thèse présente l'étude de la dynamique d'un atome ou d'une molécule en interaction avec un agrégat en vue d'étudier comment un petit système (l'atome, la molécule) échange de l'énergie électronique, cinétique et vibrationnelle avec un système possédant de très nombreux degrés de liberté (l'agrégat).Le premier système est l'étude, expérimentale et théorique, de la dynamique en temps réel d'un atome de baryum déposé sur agrégat d'argon (BaArn). L'atome de baryum est excité dans des niveaux de Rydberg, il en résulte une dynamique extrêmement riche entre le chromophore et l'agrégat. L'interprétation théorique a nécessité la conception d'une méthode de dynamique originale, permettant de traiter à la fois le grand nombre d'états excités mis en jeu, couplés à de nombreux degrés de libertés atomiques. La mise en commun des informations théoriques et expérimentales a permis d'établir l'ensemble du chemin réactionnel ayant lieu au cours de cette dynamique.Le deuxième système concerne l'étude par fluorescence de la photo-dissociation de Ca2 déposé sur agrégat d'hélium ou sur agrégat mixte hélium-argon (Ca2Hen ou Ca2ArmHen). Ces résultats sont comparés à ceux obtenu sur agrégat d'argon pur (Ca2Hen). Les différences entre ces trois types de solvant montrent que les interactions sont différentes suivant que le solvant est ''quantique'' (l'hélium) ou ''classique'' (l'argon). Plusieurs canaux réactionnels ont été mis en évidence selon que l'atome de calcium excité qui résulte de la photo-dissociation est libre ou reste solvaté par de l'hélium et/ou de l'argon. Les rapports de branchement entre ces différents canaux ont également été mesurés.
18
Heiss, Gregor Johann [Verfasser], und Don [Akademischer Betreuer] Lamb. „Single-molecule microscopy study of nano-systems : From synthetic photo-switchable nano-devices to the dynamics of naturally occurring transcription factors / Gregor Heiss. Betreuer: Don Lamb“. München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/1019479086/34.
19
O'Connor, Timothy F. III. „Synthesis and Dynamics of Photocatalytic Type-II ZnSe/CdS/Pt Metal-Semiconductor Heteronanostructures“. Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1340038781.
20
Galv?o, Carine Cristina Gon?alves. „Organiza??o social entre as f?meas de Sotalia guianensis (Van B?n?den, 1864) da Ba?a da Ilha Grande, Rio de Janeiro, Brasil“. Universidade Federal Rural do Rio de Janeiro, 2015. https://tede.ufrrj.br/jspui/handle/jspui/1341.
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2015 - Carine Cristina Gon?alves Galv?o.pdf: 2315391 bytes, checksum: 154e1cdd3a9bb2de5fd18d636c4a6543 (MD5)Made available in DSpace on 2016-10-25T13:39:22Z (GMT). No. of bitstreams: 1 2015 - Carine Cristina Gon?alves Galv?o.pdf: 2315391 bytes, checksum: 154e1cdd3a9bb2de5fd18d636c4a6543 (MD5) Previous issue date: 2015-02-24
Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ - FAPERJ
Some animals have extremely complex relationships including the formation of matriarchal societies, alliances and communities, specific long-term relationships, and formation of flexible groups, such as dolphins. Ilha Grande Bay, along with Sepetiba Bay, have the largest population of Sotalia guianensis throughout its distribution, with about 1311 individuals in the first one, and 1043 individuals in the second, where it has been registered groups with up to 450 individuals. This study aimed to analyze the social organization of the mothers of S. guianensis from Ilha Grande Bay. The mothers were considered those dolphins observed at least five times in high proximity of a calf; all its associates were also classified as females and included in the analysis. The analysis of these mothers? social structure was carried out in SOCPROG? software (2.5 version) using a Half Weight Index (HWI). It was performed an analysis of the community division by modularity which indicated that individuals do not form independent clusters. A Monte Carlo permutation test was done and showed the presence of preferred associations among some dyads. Finally, a temporal analysis was performed with the use of mathematical models fitted to the Lagged Association Rate to try to explain how associations behave over time. The social structure of the 25 mothers identified in Ilha Grande Bay seems to be poorly differentiated, forming a large social network with weak associations between dyads, and following a fission-fusion dynamics. There was no statistical difference in the associations between and within classes (mothers X females). This work is a contribution to the understanding of the species? social dynamics, which are still poorly known, and highlights the need for more research in the area.
Alguns animais possuem rela??es extremamente complexas, incluindo forma??o de sociedades matriarcais, alian?as e comunidades, relacionamentos espec?ficos de longa dura??o, e forma??o de grupos flex?veis, como ? o caso dos golfinhos. A Ba?a da Ilha Grande, juntamente com a Ba?a de Sepetiba, possui a maior popula??o de Sotalia guianensis em toda a sua distribui??o, com estimativa de 1311 indiv?duos na primeira, e 1043 indiv?duos na segunda, onde j? foram registrados grupos com at? 450 indiv?duos. Este trabalho teve como objetivo analisar a organiza??o social das m?es de S. guianensis da Ba?a da Ilha Grande. Foram consideradas m?es aqueles golfinhos vistos no m?nimo cinco vezes em forte proximidade de um filhote, e todos os seus associados foram classificados como f?meas e inclu?dos nas an?lises. A an?lise da estrutura social destas m?es foi feito no programa SOCPROG? (vers?o 2.5) atrav?s do ?ndice Half Weight (HWI). Foi feita uma an?lise de divis?o de comunidades por modularidade que indicou que os indiv?duos n?o formam agrega??es independentes. Um teste de permuta??o de Monte Carlo foi realizado e mostrou a presen?a de associa??es preferidas entre algumas duplas. Por fim, uma an?lise temporal foi realizada com a utiliza??o de modelos matem?ticos ajustados ? Lagged Association Rate para tentar explicar como as associa??es se comportam no decorrer do tempo. A estrutura social das 25 m?es identificadas de S. guianensis na Ba?a da Ilha Grande se mostrou pouco diferenciada, formando uma grande rede com fracas associa??es entre duplas, seguindo uma din?mica de fiss?o-fus?o. N?o houve diferen?a estat?stica nas associa??es entre e dentro das classes (m?es X f?meas). Este trabalho ? uma contribui??o para o entendimento das din?micas sociais da esp?cie, que ainda s?o pouco conhecidas, e ressalta a necessidade de mais pesquisas na ?rea.
21
Fugate, Elizabeth Anne. „Understanding the Role of Lattice Defects and Metal Composition Ratio on the Photochemistry of CuFeO2 toward Solar Energy Conversion“. The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu157788103637799.
22
Banks, Aaron M. „The seasonal movements and dynamics of migrating humpback whales off the east coast of Africa“. Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4109.
Annotation:
Data collected during boat-based and aerial surveys were used to describe population structure, movements, temporal patterns of migration and skin condition of humpback whales in breeding sub-stock C1-S off southern Africa. Results confirmed that the migration route along the south coast of South Africa is linked to the winter ground off Mozambique. A lack of exchange between breeding sub-stocks C1-N and C1-S was found, suggesting that these are independent of each other. Molecular analysis revealed unexpected levels of population structure between the migration route and the winter ground of C1-S, as well as the possibility that this migration route is also utilised by some individuals from breeding sub-stock C3. A skin condition of unknown aetiology that primarily affects humpback whale mother-calf pairs was identified. The first assessment of its prevalence and severity was made, providing a baseline for future monitoring. Humpback whale abundance in an inshore region of Bazaruto Archipelago, Mozambique was estimated and attempts were also made to use the limited information off Plettenberg Bay/Knysna, South Africa. In addition to improving our understanding of humpback whales from Breeding Stock C, knowledge about another baleen whale species utilising the southwest Indian Ocean was extended. The first evidence of southern right whale presence off the coast of Mozambique since the cessation of whaling was documented. It remains unknown whether this is a remnant sub-stock or the recovering South African sub-stock reoccupying its historical range.
23
Eftekhari, Ali. „Photodynamics of upconversion nanoparticles : a combined investigation at ensemble and single particle levels“. Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR086.
Annotation:
Les propriétés exceptionnelles de photoluminescence des nanoparticules up-conversion (UCNP), qui émettent de la lumière visible tout en étant éclairées par un rayonnement proche infrarouge (NIR), ont suscité l'intérêt des chercheurs du monde entier et inspiré de nombreuses applications bioanalytiques. Leur émission anti-Stokes, leur longue durée de vie de luminescence, les bandes d'absorption et d'émission étroites et multiples et leur excellente photostabilité permettent une détection multiplexée et sans bruit de fond dans des objets biologiques épais. L'émission est contrôlée par un équilibre subtil entre de nombreuses voies radiatives et non radiatives, comprenant les transferts d'énergie entre les sensibilisateurs et les activateurs et les effets d'extinction dus à la matrice hôte et à la surface. L'ensemble de ces processus explique la réponse hautement non linéaire des émissions en fonction de la puissance d'excitation. Cependant, malgré de nombreuses études dans ce domaine, la rationalisation de la dynamique de ces transferts d'énergie au sein de ces nanoparticules reste encore un défi, alors qu'elle contrôle leurs temps de vie de luminescence (montée et déclin) et leur rendement d'émission. L'objectif de cette thèse est donc d'étudier la photo-dynamique qui a lieu dans différents types d'UCNPs afin de décrire les voies énergétiques complexes qui régissent leurs propriétés d'émission en solution et au niveau de la particule unique.Tout d'abord, des UCNPs ultra-petites dopées par de l'Ytterbium (Yb, sensibilisateur) et du Thulium (Tm, activateur) ont été considérées. Ces particules, par leur petite taille, possèdent un nombre réduit d'activateurs, ce qui permet de sélectionner le nombre de processus contrôlant leur émission : grâce à une probabilité limitée de relaxation croisée entre les activateurs, la dynamique de la redistribution de l'énergie dans le réseau cinétique des activateurs est grandement simplifiée. Un examen minutieux de ces UCNP ultra-petites en solution a donc été possible en utilisant différents schémas d'irradiation (continue, impulsion nanoseconde, impulsion ms carrée, excitations médiées par le sensibilisateur ou directes par l'activateur). En particulier, la transition de phase α-β se produisant pendant la procédure de synthèse a pu être mise en évidence par l'augmentation soudaine de la durée de vie de l'état excité 3H4. En outre, nous avons également abordé l'influence de la concentration d'Yb et du revêtement de surface avec une coquille sur la dynamique d'émission des différents états excités du Tm.Pour étudier l'émission au niveau de la particule unique, nous avons développé un nouveau microscope confocal basé sur une excitation NIR à impulsions carrées de l'ordre de la milliseconde et une caméra CCD intensifiée afin de mesurer des spectres résolus dans l'espace et dans le temps. Nous discutons ici de deux applications de ce nouvel outil : (i) nous avons d'abord étudié les propriétés d'émission des assemblages de UCNPs à base de Thulium et d'Erbium (cœur et cœur-coquille). Selon l'arrangement spatial des particules à l'échelle nanométrique, nous avons pu démontrer que la dynamique d'émission des particules uniques, des monocouches 2D ou des agrégats 3D diffère en termes de rapports de bandes d'émission dépendants de la puissance et de durées de vie. (ii) nous avons examiné des systèmes hybrides composés d'UCNP uniques et de films organiques à base de pérylène en termes de spectres d'émission et de durées de vie afin d'étudier la nature des transferts d'énergie de l'UCNP vers la partie organique en fonction de la nature de l'état excité de l'émetteurThe unique photoluminescent properties of upconversion nanoparticles (UCNPs), which emit visible light while being illuminated by near infrared (NIR) radiation, have sparked the interest of researchers worldwide and inspired many bioana¬lytical applications. Their anti-Stokes emission, long luminescence lifetime, narrow and multiple absorption and emission bands, and excellent photostability enable background-free and multiplexed detection in thick biological objects. Emission is controlled by a balance of numerous radiative and non radiative pathways, including energy transfers between sensitizers and activators and quenching effects due to the host matrix and surface. Altogether, these processes account for the highly nonlinear response of the emissions to the excitation power. However, despite numerous studies in this field, rationalizing the dynamics of these energy transfers within these nanoparticles still remains a challenge, albeit it controls their time-dependent luminescence (rise and decay) and their emission yield. The purpose of this thesis is thus to investigate the photo-dynamics taking place in different types of UCNPs in order to disentangle the complex energy pathways driving their emission properties at ensemble and single particle levels.First, ultrasmall UCNPs doped with Ytterbium (Yb, sensitizer) and Thulium (Tm, activator) were considered. These particles, due to their tininess (<3nm), have a reduced number of activators, which allows selecting the number of processes controlling their emission: thanks to a limited probability of activator cross relaxation, the dynamics of the energy redistribution in the activator kinetic network is greatly simplified. A minute examination of these ultrasmall UCNP in solution was thus possible using different irradiation schemes (continuous wave, nanosecond pulse, pulse square, sensitizer-mediated or direct activator excitations). In particular, the α-to-β phase transition occurring during the synthesis procedure could be evidenced by the sudden increase of the 3H4 excited state lifetime. Additionally, we also addressed the influence of Yb concentration and surface coating with a shell on the emission dynamics of the different Tm excited states.To study the emission at the single particle level, we have developed a new confocal microscope based on a millisecond-square pulse NIR excitation and an intensified gated CCD camera in order to measure space- and time-resolved spectra. We discuss here two applications of this new tool: (i) we first investigated the emission properties of Tm- and Er-based core and core-shell UCNPs assemblies. According to the nanometric spatial arrangement of the particles, we could demonstrate that the emission dynamics of single particles, 2D monolayers or 3D aggregates differ in terms of power-dependent emission band ratios and lifetimes. (ii) we examined hybrid systems composed of single UCNPs and perylene-based organic films in terms of emission spectra and lifetimes in order to study the nature of the energy transfers from the UCNP to the dye according to the nature emitter excited state
24
Caleman, Carl. „Towards Single Molecule Imaging - Understanding Structural Transitions Using Ultrafast X-ray Sources and Computer Simulations“. Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7915.
25
Doherty, William Gerard. „Cold atom production via the photo dissociation of small molecules“. Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:523f87e0-3f19-4382-941c-74b06023b767.
Annotation:
This thesis describes the development of a relatively novel technique for the gen- eration and subsequent trapping of cold species. Molecules in a pulsed supersonic expansion are photolysed, such that the centre-of-mass velocity vector of one of the fragments is equal in magnitude but opposed in orientation to the lab-frame velocity of the precursor molecule. This technique, known as ‘Photostop’, leaves a fraction of the fragments with a narrow velocity distribution, centered around zero velocity in the lab-frame. They can be shown to have zero velocity by changing the time between photodissociation and ionisation; fragments with a high kinetic energy will leave the ionisation volume prior to interrogation. The underlying velocity distribu- tion is uncovered by using the velocity-map imaging technique, and the temperature of the fragments can be determined. The method was originally optimised for the molecular case. Cold NO has been produced from the dissociation of NO₂ molecules, and a single rotational state has been shown to remain in the ionisation volume 10 μs after dissociation, implying a sample temperature of 1.17 K. Using the optimised experimental conditions de- rived from the velocity cancellation of NO, the atomic case is demonstrated for the dissociation of Br₂ to give zero-velocity Br fragments. The Br atoms are seen for delay times in excess of 100 μs, showing the greater applicability of the method to the atomic case. The temperature of the residual atoms is shown to be in the milliKelvin regime, as determined through detailed Monte Carlo simulation of the motion of the stopped atoms. The possibility of trapping the ultracold Br atoms in a magnetic field is explored, and a quadrupolar trap created between two per- manent bar magnets is demonstrated to confine the atoms spatially, within the ion extraction optics, for delays in excess of 1 ms. The Photostop technique is intended to be a stepping stone on the way to widening the number of chemical species available for study in the ultracold regime. The possibility of improvements to the experiment is considered, in order to increase the efficiency of the experiment such that the number density becomes high enough to be viable as a source of atoms for use in cold chemical reactive studies. The possibility of extending the method so as to be used as a tunable velocity source of atoms is also discussed.
26
Albero, Sancho Josep. „Photo-induced charge transfer reactions in quantum dot based solar cells“. Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/81717.
Annotation:
En esta tesis doctoral se han estudiado procesos fundamentales de reacciones de transferencia de carga en películas mesoporosas de dióxido de titanio sensitivizado con puntos cuánticos, en películas finas de mezclas polímero:puntos cuánticos y en dispositivos completos de mezclas del polímero PCPDTBT y puntos cuánticos de CdSe en operaciones de trabajo reales.
Los resultados obtenidos permiten abordar la fabricación de dispositivos fotovoltaicos con un conocimiento de los procesos de recombinación que limitan la eficiencia de las celdas más amplio. Y por tanto, se demuestra la posibilidad de fabricar celdas solares basadas en puntos cuánticos con eficiencias iguales o superiores a los dispositivos fotovoltaicos orgánicos.The fundamental processes of the charge transfer reactions between titania dioxide mesoporous films and quantum dots, in blend films of the semiconductor polymer P3HT and CdSe quantum dots and in complete devices fabricated with the polymer PDPCTBT and CdSe quantum dots in working conditions have been studied in this doctoral thesis. The obtained results allow the fabrication of photovoltaic devices with a deeper and wider knowledge of the recombination processes that limit the device efficiency. Therefore, it is demonstrated the possibility of fabrication of quantum dot based solar cells with efficiencies similar or higher than the organic photovoltaic devices.
27
Gnodtke, Christian. „Dynamik endlicher Vielteilchen-Systeme in intensiven Röntgenlaserpulsen“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-67676.
Annotation:
Die Arbeit beschäftigt sich mit der neuartigen Wechselwirkung von intensiven und ultrakurzen Röntgenlaserpulsen mit atomaren endlichen Systemen, die derzeit durch eine neue Generation von Lichtquellen, sogenannter X-ray free-electron laser (XFEL) zugänglich gemacht wird.
Eine der Vorzeigeanwendungen der XFELs ist die zukünftig potentiell mögliche Strukturbestimmung endlicher nicht-periodischer Systeme mit atomarer Auflösung durch Diffraktion. Hierbei stellt sich der durch die hohe notwendige Pulsintensität bedingte Strahlenschaden an dem System als limitierender Faktor heraus, der ein detailliertes Verständnis der durch Photoabsorption induzierten Dynamik voraussetzt, um diese Art der "Mikroskopie" zum Erfolg zu führen.
Wir verwenden daher zur Beschreibung der laserinduzierten Dynamik ein mikroskopisches Modell in dem Photoionisation und inner-atomare Zerfallsprozesse durch quantenmechanische Raten behandelt werden und die Dynamik der Ionen und energetischen Elektronen in einer klassischen Molekulardynamik-Simulation erfasst wird.
Eine Neuerung gegenüber bisherigen Modellen ist die Berücksichtigung der Ionisation von Atomen durch starke interne Felder in dem hoch-geladenen System.
Durch eine Anwendung des Modells auf Neoncluster kann gezeigt werden, dass diese Feldionisation einen wichtigen Beitrag zur laserinduzierten Dynamik darstellt. Sie führt zur ultraschnellen Formation eines Nanoplasmas, welches sich im Kern des geladenen Clusters ansammelt und dort die Ladung der Clusterionen neutralisert. Hierdurch wird eine vorzeitige Coulomb-Explosion des Clusters vermieden.
Es wird dargelegt, dass dieser Mechanismus der lokalen Schadensreduzierung durch die Einbettung des Clusters in ein Heliumtröpfchen auf den gesamten Cluster ausgeweitet werden kann, da durch Feldionisation und Migration von Elektronen die vollständige laserbedingte Aufladung des Clusters auf das Heliumtröpfchen transferiert wird. Eine Analyse der resultierenden Diffraktionsmuster bestätigt, dass der reduzierte Strahlenschaden am Cluster den Anwendungsbereich für Diffraktionsexperimente erheblich ausweitet.
Kürzlich wurde am SLAC National Accelerator Laboratory der erste XFEL in Betrieb genommen. Eine Modifikation des Modells auf dort bereits erzielbare Wellenlängen wird genutzt um Vorhersagen über das Photoabsorptionsverhalten, aus dem alle weiteren Schäden folgen, an kleinen Neoncluster zu treffen. Hiermit lassen sich bereits jetzt durch den Vergleich zu Experimenten die wichtigen Schadensmechanismen und ihre theoretische Beschreibung testen.
Es wird ferner das interessante Relaxationsverhalten des durch massive Photoionisation in XFEL-Strahlung erzeugten Elektronenplasmas untersucht.
Diese neuartige Anregung erfolgt auf einer Femtosekunden-Zeitskala und produziert eine hohe Dichte an energetischen Elektronen. Wir beschreiben dieses Plasma durch ein generisches Modell seiner Vielteilchen-Dynamik. Hierbei kann der gesamte Parameterraum des Modells in vier Klassen unterteilt werden, die sich nach Anregungsgrad, der den Elektronenverlust des Plasmas regelt, und Anregungsdauer, die die transiente Dynamik beeinflusst, unterscheiden. Speziell der Bereich starker Anregung bei gleichzeitig kurzer Anregungsdauer zeigt ein interessantes neues Verhalten, bei dem sich eine Equilibrierung des Systems im Kontinuum andeutet.
28
Gnodtke, Christian. „Dynamik endlicher Vielteilchen-Systeme in intensiven Röntgenlaserpulsen“. Doctoral thesis, Max-Planck-Institut für Physik komplexer Systeme, 2010. https://tud.qucosa.de/id/qucosa%3A25554.
Annotation:
Die Arbeit beschäftigt sich mit der neuartigen Wechselwirkung von intensiven und ultrakurzen Röntgenlaserpulsen mit atomaren endlichen Systemen, die derzeit durch eine neue Generation von Lichtquellen, sogenannter X-ray free-electron laser (XFEL) zugänglich gemacht wird.
Eine der Vorzeigeanwendungen der XFELs ist die zukünftig potentiell mögliche Strukturbestimmung endlicher nicht-periodischer Systeme mit atomarer Auflösung durch Diffraktion. Hierbei stellt sich der durch die hohe notwendige Pulsintensität bedingte Strahlenschaden an dem System als limitierender Faktor heraus, der ein detailliertes Verständnis der durch Photoabsorption induzierten Dynamik voraussetzt, um diese Art der "Mikroskopie" zum Erfolg zu führen.
Wir verwenden daher zur Beschreibung der laserinduzierten Dynamik ein mikroskopisches Modell in dem Photoionisation und inner-atomare Zerfallsprozesse durch quantenmechanische Raten behandelt werden und die Dynamik der Ionen und energetischen Elektronen in einer klassischen Molekulardynamik-Simulation erfasst wird.
Eine Neuerung gegenüber bisherigen Modellen ist die Berücksichtigung der Ionisation von Atomen durch starke interne Felder in dem hoch-geladenen System.
Durch eine Anwendung des Modells auf Neoncluster kann gezeigt werden, dass diese Feldionisation einen wichtigen Beitrag zur laserinduzierten Dynamik darstellt. Sie führt zur ultraschnellen Formation eines Nanoplasmas, welches sich im Kern des geladenen Clusters ansammelt und dort die Ladung der Clusterionen neutralisert. Hierdurch wird eine vorzeitige Coulomb-Explosion des Clusters vermieden.
Es wird dargelegt, dass dieser Mechanismus der lokalen Schadensreduzierung durch die Einbettung des Clusters in ein Heliumtröpfchen auf den gesamten Cluster ausgeweitet werden kann, da durch Feldionisation und Migration von Elektronen die vollständige laserbedingte Aufladung des Clusters auf das Heliumtröpfchen transferiert wird. Eine Analyse der resultierenden Diffraktionsmuster bestätigt, dass der reduzierte Strahlenschaden am Cluster den Anwendungsbereich für Diffraktionsexperimente erheblich ausweitet.
Kürzlich wurde am SLAC National Accelerator Laboratory der erste XFEL in Betrieb genommen. Eine Modifikation des Modells auf dort bereits erzielbare Wellenlängen wird genutzt um Vorhersagen über das Photoabsorptionsverhalten, aus dem alle weiteren Schäden folgen, an kleinen Neoncluster zu treffen. Hiermit lassen sich bereits jetzt durch den Vergleich zu Experimenten die wichtigen Schadensmechanismen und ihre theoretische Beschreibung testen.
Es wird ferner das interessante Relaxationsverhalten des durch massive Photoionisation in XFEL-Strahlung erzeugten Elektronenplasmas untersucht.
Diese neuartige Anregung erfolgt auf einer Femtosekunden-Zeitskala und produziert eine hohe Dichte an energetischen Elektronen. Wir beschreiben dieses Plasma durch ein generisches Modell seiner Vielteilchen-Dynamik. Hierbei kann der gesamte Parameterraum des Modells in vier Klassen unterteilt werden, die sich nach Anregungsgrad, der den Elektronenverlust des Plasmas regelt, und Anregungsdauer, die die transiente Dynamik beeinflusst, unterscheiden. Speziell der Bereich starker Anregung bei gleichzeitig kurzer Anregungsdauer zeigt ein interessantes neues Verhalten, bei dem sich eine Equilibrierung des Systems im Kontinuum andeutet.
29
Gonon, Benjamin. „Simulations quantiques non-adiabatiques d’un photo-interrupteur moléculaire vers un dialogue expérience-théorie“. Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT186/document.
Annotation:
Cette thèse a pour objet l’étude et le contrôle de la photo-réactivité d’interrupteurs moléculaires, en particulier la photo-isomérisation des spiropyranes. Ce travail théorique a été réalisé en collaboration étroite avec l’équipe expérimentale PFL de l’ICB à Dijon. Des simulations de dynamique quantique non-adiabatique ont été réalisées afin de reproduire et rationaliser les résultats expérimentaux de spectroscopie d’absorption transitoire résolue en temps. Ces expériences ont montré une photo-réactivité ultra-rapide (~ 100 fs) suite à une excitation par une pulse LASER ultra-court. Celle-ci est interprétée comme un mécanisme de conversion interne entre le premier état électronique excité singulet et l’état fondamental via une intersection conique. L’étude théorique a utilisé la réaction d’ouverture de cycle du benzopyrane comme modèle. Les développements réalisés ont porté sur : (1) L’exploration du mécanisme réactionnel et le calcul de surfaces d’énergie potentielle via des méthodes de chimie quantique post-CASSCF perturbatives (XMCQDPT2). Cette analyse a montré des résultats variant fortement par rapport à ceux relevés dans la littérature à des niveaux de calcul moins élevés. (2) Le développement d’un modèle de surfaces d’énergie potentielle électronique par la construction d’un hamiltonien diabatique à partir de données ab initio XMCQDPT2. Du fait de l’importante anharmonicité de l’état électronique fondamental, nous avons mis en place une approche effective en rupture avec les études antérieures. (3) La réalisation de simulations de dynamique quantique non-adiabatique par la méthode MCTDH. Les résultats obtenus sont en très bon accord avec les résultats expérimentaux. L’inclusion explicite du pulse LASER a permis de reproduire et de rationaliser l’effet de contrôle par mise en forme d’impulsion observé expérimentalement. Ce travail a ainsi permis la mise en place d’une collaboration et d’un dialogue théorie/expérience effectifsThis thesis adresses the study and control of the photo-reactivity of molecular switches, here the photo-isomerisation of spiropyrans. This theoretical work has been achieved in close collaboration with the experimental team PFL within the ICB in Dijon. Non-adiabatic quantum dynamics simulations were carried out so as to reproduce and rationalise the experimental results from time-resolved transient absorption spectroscopy. Such experiments have demonstrated ultra-fast photo-reactivity (~ 100 fs) following excitation by an ultra-short LASER pulse. It is interpreted as an internal conversion mechanism between the first singlet excited eletronic state and the ground state via a conical intersection. The theoretical study used the ring-opening reaction of benzopyran as a model. Developments were made regarding: (1) The exploration of the reaction mechanism and the computation of potential energy surfaces with perturbative, post-CASSCF quantum chemistry methods (XMCQDPT2). This investigation showed that results changed significantly compared to those reported in the literature with lower-level calculations. (2) The generation of a diabatic Hamiltonian based on ab initio XMCQDPT2 data. Owing to the significant anharmonicity in the ground electronic state, we designed a new effective approach, quite different from the previous studies. (3) The production of non-adiabatic quantum dynamics simulations using the MCTDH method. The results thus obtained are in excellent agreement with the experimental ones. Including explicitly the LASER pulse allowed us to reproduce and rationalise the action of pulse shaping on control observed in experiments. The present work thus made possible the succesful implementation of a theoretical/experimental collaboration
30
Raclot, Damien. „MÉTHODOLOGIE D'EXPLOITATION QUANTITATIVE DES PHOTOGRAPHIES AÉRIENNES D'INONDATION DE PLAINE“. Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2003. http://tel.archives-ouvertes.fr/tel-00003257.
Annotation:
Ce travail est centré sur la mise au point d'une méthodologie d'exploitation de photographies aériennes prises en période de crue pour en extraire, au moment de la prise de vue, la cote de l'eau en tout point de la plaine. Cette méthodologie, appelée "approche-photo", comporte une phase de traitement de télédétection, une phase d'analyse spatiale et de structuration de l'information dans un SIG, et une phase novatrice et originale de fusion et mise en cohérence de l'ensemble des données extraites (développement d'un algorithme de mise en cohérence inspiré de l'hydraulique et de techniques empruntées au domaine de l'intelligence artificielle). La méthode a été testée sur trois sites d'étude, couvrant un panel très large de contextes. Un travail important de validation et d'analyse de sensibilité a permis de montrer que la précision des estimations de la cote de l'eau, produites sous forme de fourchette [Min, Max], était de l'ordre décimétrique, résultat tout à fait compatible avec les exigences hydrauliques. "L'approche-photo" constitue donc une valorisation quantitative des archives photographiques concernant les crues historiques. Une première retombée provient de la structuration de ces résultats au sein d'un SIG, ce qui les rend facilement mobilisables pour toutes les étapes de la gestion du risque d'inondation. Une seconde retombée, bien plus importante, résulte de la complémentarité de "l'approche-photo" avec les approches traditionnelles. Celle avec la modélisation hydraulique a été approfondie par la mise en œuvre d'un modèle 2D sur la basse vallée de l'Hérault. Une confrontation des résultats a permis de mettre en avant les apports réciproques : "l'approche-photo" comme aide à la structuration, au calage et à la validation de la modélisation et, à l'inverse, la modélisation hydraulique comme aide à la validation de "l'approche-photo".Cette thèse se veut une illustration de l'intérêt d'une démarche multidisciplinaire.
31
Wallace, Amy. „Dynamics of Stony Coral Assemblages on Patch Reefs of the Upper Florida Reef Tract, Including Biscayne National Park“. Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3400.
Annotation:
The patch reefs located in Biscayne National Park (BNP) are some of the most northern reefs of the Florida reef system. The focus of my study is seven patch reefs that were first surveyed annually between 1977 and 1981, revealing 8% - 28% cover by scleractinian corals. An assessment of BNP patch reefs completed in 2000 reported that coral cover had decreased to approximately 0.4% - 10%. The once dominant species in the Florida reef tract, Acropora palmata and A. cervicornis, have rapidly declined over time and were not found in any transects during the 2000 survey.
This study is a re-assessment of the BNP patch reefs surveyed in 1977-1981. In addition, one patch reef from BNP and three in upper keys region of the Florida Keys National Marine Sanctuary (FKNMS) have been included (a total of 11 patch reefs, all with historical data available). This study found 2% - 13% coral cover at these 11 reefs using a photographic survey (Point Count) and 4% - 21% coral cover using Atlantic and Gulf Rapid Reef Assessment (AGRRA) survey methods. These results are relatively similar to results reported for the same patch reefs in the 1990s and in 2002, indicating that the major changes occurred earlier with the extreme decline in Acropora spp. Montastraea annularis complex cover has also declined substantially at the BNP sites from 5.4% in 1977-81 to 1.3% in 2009.
Although the number of species recoded on the seven resurveyed BNP patch reefs was only 23, compared with 28 recorded in the 1977-81 study, all species are still present in the region surveyed, indicating no actual loss of over all species richness.
32
Woodhouse, Joyce. „Etude d'une protéine fluorescente photo-commutable par cristallographie résolue en temps en utilisant les lasers à électrons libres“. Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY026/document.
Annotation:
Les protéines fluorescentes photocommutables (RSFPs) ont la propriété de passer d’un état fluorescent à un état non-fluorescent en réponse à la lumière. Cette propriété en fait des outils de marquage pour la microscopie de super-résolution (ou nanoscopie). Le mécanisme de photocommutation implique l’isomérisation du chromophore ainsi qu’un changement d’état de protonation de ce dernier. Le mécanisme a été très étudié par différentes approches de spectroscopie et de simulation mais reste encore mal compris, l’ordre séquentiel des évènements est notamment encore débattu. Certains de ces évènements de la photocommutation se déroulent à des échelles de temps très courtes, ce qui rend difficile l’étude structurale par cristallographie des rayons X à l’aide des sources synchrotron actuelles dont la résolution temporelle est encore limitée. Les lasers à électrons libres (XFELs) sont une nouvelle source de rayons X produisant des impulsions suffisamment courtes pour permettre l’étude structurale des intermédiaires précoces ou à courte durée de vie qui se forment ou cours de la photocommutation, et suffisamment brillantes pour permettre la collecte de données cristallographiques sur des cristaux de tailles nano- et micrométrique. L’utilisation de ce nouveau genre d’instrument a permis l’émergence de la cristallographie sérielle, une nouvelle approche de la cristallographie des rayons X. Cette approche a depuis été adaptée aux lignes synchrotrons.Le travail présenté ici se focalise sur l’étude de rsEGFP2, une protéine fluorescente photocommutable de la famille de la GFP. Il y est décrit la mise au point d’un protocole de microcristallisation permettant l’obtention d’échantillons en vue d’une expérience de cristallographie résolue en temps au XFEL. Un mécanisme de photocommutation y est proposé à travers le résultat de deux expériences sur les deux XFELs actuellement opérationnels, à des échelles de temps différentes, dévoilant un chromophore « twisté » à l’état excité ainsi qu’un état cis protoné de ce dernier. La caractérisation structurale des variants de rsEGFP2 par cristallographie d’oscillation « classique » combinée à la découverte fortuite d’une conformation alternée du chromophore dans l’état non-fluorescent, issue d’expérience de cristallographie sérielle, apporte un complément d’explication des propriétés photophysiques de la protéineReversibly switchable fluorescent proteins (RSFPs) are able to reversibly toggle between a fluorescent on-state and a non-fluorescent off-state under visible light irradiation. This property makes them a suitable marker used in super-resolution microscopy (or nanoscopy). The photo-switching mechanism involves isomerisation of the chromophore and a change of its protonation state. This mechanism has been well studied but remains poorly understood. The structural nature and the sequential order of atomistic events are still under debate. Some of them take place on the ultra-fast time scale and make structural investigation by X-ray crystallography impossible using current synchrotron radiation sources whose temporal resolution they offer is limited. X-ray free electron lasers (XFELs) are a new kind of X-ray source producing femtosecond pulses that allow structural investigation of ultra-fast intermediates during photoswitching. They are also so bright that crystallographic data collection from micro- and nanometer-sized crystals became possible. The bright and short XFEL pulses required a new methodology to be developed, the so-called serial crystallography methodology. This method is now being adapted to synchrotron radiation facilities.Here is presented a time-resolved crystallography study of the reversibly switchable green fluorescent protein 2 (rsEGFP2). A microcrystallization protocol is described allowing the preparation of suitable samples in large amounts for time-resolved serial crystallography experiments. A photoswitching mechanism of rsEGFP2 is proposed based on crystallographic results obtained from data collected at the two XFEL facilities currently fully operational, i.e. the LCLS in the USA and SACLA in Japan. In particular, the structure of two photoswitching intermediates have been determined, one featuring a twisted chromophore in the excited state and the other displaying a protonated cis isomer of the chromophore in the ground state. The structural characterization of rsEGFP2 variants by traditional oscillation crystallography combined with the serendipitous discovery of an alternate chromophore conformation in the off-state during an XFEL experiment provided unique insight into the photophysical behavior of the protein
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Abdul, Nour Charles. „Identification de paramètres optiques de structures tissulaires : instrumentation prototype associée : application à la dosimétrie de la thérapie photo-dynamique“. Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL006N.
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La thérapie photodynamique anticancéreuse repose sur la production d'oxygène singulet lors d'une réaction photochimique entre un agent photosensibilisant fixé sur les cellules cancéreuses et une irradiation lumineuse dans le rouge. Pour avoir une efficacité thérapeutique, il est important de connaitre l'atténuation lumineuse dans les tissus et ainsi la profondeur de pénétration de la lumière afin de définir une dosimétrie optique précise. La connaissance de ce paramètre doit s'effectuer en continu et in situ. Les mesures préliminaires de la rétrodiffusion et de la transmission lumineuse dans des solutions biologiques ainsi que le développement d'une simulation numérique décrivant les deux phénomènes ont été des bases solides pour la réalisation d'un capteur à fibres optiques capable d'estimer la profondeur de pénétration de la lumière à partir de la rétrodiffusion de celle-ci dans ces milieux. Une instrumentation est associée au capteur pour permettre l'estimation de la profondeur de pénétration de la lumière dans les tissus en continu et in situ. Les résultats des mesures avec le capteur dans des milieux liquides et solides sont rapportés puis comparés aux valeurs de référence. Le dispositif réalisé peut être utilisé pour des mesures cliniques directes
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Piguet, Joachim. „Advanced Fluorescence Microscopy to Study Plasma Membrane Protein Dynamics“. Doctoral thesis, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-178147.
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Membrane protein dynamics is of great importance for living organisms. The precise localization of proteins composing a synapse on the membrane facing a nerve terminus is essential for proper functioning of the nervous system. In muscle fibers, the nicotinic acetylcholine is densely packed under the motor nerve termini. A receptor associated protein, rapsyn, acts as a linker between the receptor and the other components of the synaptic suramolecular assembly. Advances in fluorescence microscopy have allowed to measure the behavior of a single receptor in the cell membrane. In this work single-molecule microscopy was used to track the motion of ionotropic acetylcholine (nAChR) and serotonin (5HT3R) receptors in the plasma membrane of cells. We present methods for measuring single-molecule diffusion and their analysis. Single molecule tracking has shown a high dependence of acetylcholine receptors diffusion on its associated protein rapsyn. Comparing muscle cells that either express rapsyn or are devoid of it, we found that rapsyn plays an important role on receptor immobilization. A three-fold increase of receptor mobility was observed in muscle cells devoid of rapsyn. However, in these cells, a certain fraction of immobilized receptors was also found immobile. Furthermore, nAChR were strongly confined in membrane domains of few tens of nanometers. This showed that membrane composition and membrane associated proteins influence on receptor localization. During muscle cell differentiation, the fraction of immobile nAChR diminished along with the decreasing nAChR and stable rapsyn expression levels. The importance of rapsyn in nAChR immobilization has been further confirmed by measurements in HEK 293 cells, where co-expression of rapsyn increased immobilization of the receptor. nAChR is a ligand-gated ion-channel of the Cys-loop family. In mammals, members of this receptor family share general structural and functional features. They are homo- or hetero-pentamers and form a membrane-spanning ion channel. Subunits have three major regions, an extracellular ligand binding domain, a transmembrane channel and a large intracellular loop. 5HT3R was used as a model to study the effect of this loop on receptor mobility. Single-molecule tracking experiments on receptors with progressively larger deletions in the intracellular loop did not show a dependence of the size of the loop on the diffusion coefficient of mobile receptors. However, two regions were identified to play a role in receptor mobility by changing the fractions of immobile and directed receptors. Interestingly, a prokaryotic homologue of cys-loop receptors, ELIC, devoid of a large cytoplasmic loop was found to be immobile or to show directed diffusion similar as the wild-type 5HT3R. The scaffolding protein rapsyn stabilizes nAChR clusters in a concentration dependent manner. We have measured the density and self-interactions of rapsyn using FRET microscopy. Point-mutations of rapsyn, known to provoke myopathies, destabilized rapsyn self-interactions. Rapsyn-N88K, and R91L were found at high concentration in the cytoplasm suggesting that this modification disturbs membrane association of rapsyn. A25V was found to accumulate in the endoplasmic reticulum. Fluorescent tools to measure intracellular concentration of calcium ions are of great value to study the function of neurons. Rapsyn is highly abundant at the neuromuscular junction and thus is a genuine synaptic marker. A fusion protein of rapsyn with a genetically encoded ratiometric calcium sensor has been made to probe synapse activity. This thesis has shown that the combined use of biologically relevant system and modern fluorescence microscopy techniques deliver important information on pLGIC behaviour in the cell membrane.QC 20151217
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Zhang, Zailan. „Electronic structures, quasi-particle and gap dynamics in copper oxides superconductors using Time and Angle Resolved Photoemission Spectroscopy“. Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066126/document.
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Les supraconducteurs à base d'oxyde de cuivre ont fait l'objet d'études approfondis mais ils restent toujours au centre de nombreux débats. Après 30 années de recherche, certaines questions scientifiques ont été éclairées, alors que d'autres restent controversées. L'évolution du paramètre d'ordre supraconducteur avec la température et le dopage en est un cas exemplaire. Dans cette thèse nous décrivons notre étude systématique de supraconducteurs à haute temperature critique par Angle Resolved PhotoEmission Spectroscopy (ARPES: Spectroscopie de photoémission résolue en angle) et par ARPES resolué en temps. On a mesuré du Bi2Sr2CaCu2O8+δ avec dopage optimale (c.a.d. montrant la Tc la plus élevé), afin d'explorer la possibilité que une photo-excitation très intense du supraconducteur crée un état avec des paires de Cooper incohérentes et sans aucune densité superfluide. La méthode expérimentale employée nous a permis de mesurer la dynamique des électrons hors équilibre et du gap supraconducteur, en fournissant des informations complémentaires à l'ARPES conventionnelle et aux mesures optiques. Nos données de ARPES résolue en temps sur Bi2Sr2CaCu2O8+δ montrent que une photo-excitation génère un effondrement du gap supraconducteur qui dépend du moment. La relaxation des quasi-particules acquiert une composante rapide à la fluence F de seuil ou le gap s'effondre complètement. La comparaison entre le F_pair et le F_phase spar spectroscopie optique THz résolue en temps suggère que il y aurait un régime de fluence ou les paires de Cooper survivent, mais ne portant plus un courant superfluide.Un autre défi majeur dans la physique des cuprates supraconducteurs à haute température critique (HTSCs) est la compréhension de l'état normale à haute température. Nous presentons aussi un étude ARPES du pseudo-gap proche du point nodale de la surface de Fermi dans le système La2-xBaxCuO4 (LBCO), qui montre un possible lien avec les modulations de densité de charge (stripes). Nos données suggerent que le gap s'ouvre en dessous de la transition LTT-LTO associé à l'apparition des modulations de charge tandis que la fonction spectrale n'est pas affecté par le modulation de la densité de spin. On observe aussi que la structure de bande dans LBCO est rénormalisé avant le "kink" à environs 70 meV. Nous corrélons cette rénormalisation en énergie et moment à l'amollissement du mode d'étirement de la liaison Cu-OThe superconductors of the copper-oxide family have been matter of extensive investigations and are still subject of fierce debates. After 30 years of research, some issues have been settled, whereas others remain controversial. The evolution of the superconducting order parameter with temperature and doping level is an exemplary case. In this thesis, we report a systematic Time resolved Angle Resolved PhotoEmission Spectroscopy (ARPES) study of the optimally doped Bi2Sr2CaCu2O8+δ to explore the possibility that an intense photoexcitation of the superconductor can generate a state with incoherent copper pairs and no superfluid density. The employed experimental methods allow us to measure the dynamics of non-equilibrium electrons and of the superconducting gap, providing complementary information to conventional ARPES and optical measurement. Our time resolved ARPES data of Bi2Sr2CaCu2O8+δ, report a momentum-dependent collapse of the superconducting gap upon photoexcitation. Interestingly, the QP relaxation develops a faster component at the threshold fluence F_pair where the gap has fully collapsed. The comparison between the F_pair and the F_phase extracted by tr-THz suggested the existence a fluence regime when the Cooper pairs have survived, but without holding superfluid current. A second major challenge in the physics of HTSCs is the poor understanding of the normal phase at high temperature. We also present the ARPES study of the near nodal pseudo-gap in La2-xBaxCuO4 (LBCO) to show a possible link with charge modulation (stripes). Our data show that the near nodal gap open below the LTT-LTO transition, which is linked to the formation of such modulations, instead of the one where spin modulations appear. The data show that the band structure of LBCO is affected by a renormalization setting in prior to the 70 meV kink. We were able to correlate this renormalization of the ARPES data to the region where the Cu-O bond-stretching mode soften, both in energy and momentum space
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Zhang, Zailan. „Electronic structures, quasi-particle and gap dynamics in copper oxides superconductors using Time and Angle Resolved Photoemission Spectroscopy“. Electronic Thesis or Diss., Paris 6, 2017. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2017PA066126.pdf.
Annotation:
Les supraconducteurs à base d'oxyde de cuivre ont fait l'objet d'études approfondis mais ils restent toujours au centre de nombreux débats. Après 30 années de recherche, certaines questions scientifiques ont été éclairées, alors que d'autres restent controversées. L'évolution du paramètre d'ordre supraconducteur avec la température et le dopage en est un cas exemplaire. Dans cette thèse nous décrivons notre étude systématique de supraconducteurs à haute temperature critique par Angle Resolved PhotoEmission Spectroscopy (ARPES: Spectroscopie de photoémission résolue en angle) et par ARPES resolué en temps. On a mesuré du Bi2Sr2CaCu2O8+δ avec dopage optimale (c.a.d. montrant la Tc la plus élevé), afin d'explorer la possibilité que une photo-excitation très intense du supraconducteur crée un état avec des paires de Cooper incohérentes et sans aucune densité superfluide. La méthode expérimentale employée nous a permis de mesurer la dynamique des électrons hors équilibre et du gap supraconducteur, en fournissant des informations complémentaires à l'ARPES conventionnelle et aux mesures optiques. Nos données de ARPES résolue en temps sur Bi2Sr2CaCu2O8+δ montrent que une photo-excitation génère un effondrement du gap supraconducteur qui dépend du moment. La relaxation des quasi-particules acquiert une composante rapide à la fluence F de seuil ou le gap s'effondre complètement. La comparaison entre le F_pair et le F_phase spar spectroscopie optique THz résolue en temps suggère que il y aurait un régime de fluence ou les paires de Cooper survivent, mais ne portant plus un courant superfluide.Un autre défi majeur dans la physique des cuprates supraconducteurs à haute température critique (HTSCs) est la compréhension de l'état normale à haute température. Nous presentons aussi un étude ARPES du pseudo-gap proche du point nodale de la surface de Fermi dans le système La2-xBaxCuO4 (LBCO), qui montre un possible lien avec les modulations de densité de charge (stripes). Nos données suggerent que le gap s'ouvre en dessous de la transition LTT-LTO associé à l'apparition des modulations de charge tandis que la fonction spectrale n'est pas affecté par le modulation de la densité de spin. On observe aussi que la structure de bande dans LBCO est rénormalisé avant le "kink" à environs 70 meV. Nous corrélons cette rénormalisation en énergie et moment à l'amollissement du mode d'étirement de la liaison Cu-OThe superconductors of the copper-oxide family have been matter of extensive investigations and are still subject of fierce debates. After 30 years of research, some issues have been settled, whereas others remain controversial. The evolution of the superconducting order parameter with temperature and doping level is an exemplary case. In this thesis, we report a systematic Time resolved Angle Resolved PhotoEmission Spectroscopy (ARPES) study of the optimally doped Bi2Sr2CaCu2O8+δ to explore the possibility that an intense photoexcitation of the superconductor can generate a state with incoherent copper pairs and no superfluid density. The employed experimental methods allow us to measure the dynamics of non-equilibrium electrons and of the superconducting gap, providing complementary information to conventional ARPES and optical measurement. Our time resolved ARPES data of Bi2Sr2CaCu2O8+δ, report a momentum-dependent collapse of the superconducting gap upon photoexcitation. Interestingly, the QP relaxation develops a faster component at the threshold fluence F_pair where the gap has fully collapsed. The comparison between the F_pair and the F_phase extracted by tr-THz suggested the existence a fluence regime when the Cooper pairs have survived, but without holding superfluid current. A second major challenge in the physics of HTSCs is the poor understanding of the normal phase at high temperature. We also present the ARPES study of the near nodal pseudo-gap in La2-xBaxCuO4 (LBCO) to show a possible link with charge modulation (stripes). Our data show that the near nodal gap open below the LTT-LTO transition, which is linked to the formation of such modulations, instead of the one where spin modulations appear. The data show that the band structure of LBCO is affected by a renormalization setting in prior to the 70 meV kink. We were able to correlate this renormalization of the ARPES data to the region where the Cu-O bond-stretching mode soften, both in energy and momentum space
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Bender, Vitor Cristiano. „Modelagem e acionamento de diodos orgânicos emissores de luz (OLEDs) para sistemas de iluminação“. Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/3691.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis thesis presents the study and characterization of organic light-emitting diodes (OLEDs) with the proposal of obtaining an equivalent model that is useful in the OLED driver design and in lighting systems projects. Initially, a literature review covering the operating principle and the constructive aspects of OLEDs is presented. From this, a model that integrates scale, photometrical, electrical and thermal aspects is proposed. This model is static and dynamic and is called EFET. A procedure for parameter identification of the model is proposed, jointly with an analysis of the intrinsic capacitance effect on the OLED electrical, thermal and photometrical performance. The proposed model is able to predict and simulate the OLED based lighting systems before building, saving time and cost. The model is validated using different OLED samples and conclusions are derived from the experimental validation and simulation results. An approach considering the dimming methods of OLEDs is presented, showing the chromatic impact caused by each method. Finally, an OLED driver based on the concept of switched capacitor converters is proposed. The thesis results are satisfactory and provide an enhancement to the state of the art in modeling and OLED driving.
A presente tese de doutorado apresenta o estudo e a caracterização de diodos orgânicos emissores de luz (OLEDs) com a proposta de um modelo equivalente que é útil no desenvolvimento de circuitos de acionamento e na análise de OLEDs, quando aplicados em sistemas de iluminação. Inicialmente, é apresentada uma revisão bibliográfica contemplando o princípio de funcionamento e os aspectos construtivos dos OLEDs. A partir disto, um modelo que integra os aspectos de escala, fotométricos, elétricos e térmicos é proposto. Esse modelo é denominado EFET e é dividido em estático e dinâmico. Uma proposta de procedimento para identificação dos parâmetros do modelo é apresentada, juntamente com a análise do efeito da capacitância intrínseca dos OLEDs no seu desempenho elétrico, térmico e fotométrico. Com o modelo proposto pode-se predizer e simular o comportamento dos OLEDs antes de construir o sistema de iluminação, reduzindo custos e tempo de desenvolvimento. O modelo é validado empregando diferentes amostras de OLEDs. Conclusões são obtidas a partir da validação experimental e de simulações empregando simuladores elétricos e da fluidodinâmica computacional através do método de elementos finitos. Uma abordagem considerando os métodos de ajuste da intensidade luminosa de OLEDs é apresentada, evidenciando o impacto cromático provocado por cada método. Por fim, um circuito de acionamento para OLEDs baseado no conceito de capacitores chaveados é proposto. Os resultados obtidos são satisfatórios e proporcionam um incremento ao estado da arte da modelagem e acionamento de OLEDs.
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PESTANA, Rayner Carvalho. „Para a implanta??o da meritocracia na gest?o de carreira: implica??es dos contextos cultural, gerencial e pol?tico de uma empresa estatal federal brasileira“. Universidade Federal Rural do Rio de Janeiro, 2015. https://tede.ufrrj.br/jspui/handle/jspui/1343.
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The transformation of the Brazilian Public Management, specifically about the adoption of modern tools for human resources, has been happening since the last century and the concern about the introduction of meritocracy in career management is still considered a recurring theme. An evidence of that is the guidance from management and control department of federal state-owned companies to adopt meritocracy in their career management systems. The organization studied here, although already have passed thirteen years of validity of its current jobs and salaries plan, seems not yet to have been able to establish career management policies based on meritocracy. Due to the problem presented, the main objective of this research focused on raising the implications of the organizational context of a Brazilian federal state-owned company, dependent on the Treasury, for the introduction of meritocracy in career management. An applied qualitative research was carried out, configured in the form of a single case study to map the features of the current cultural, managerial and political contexts and to interpret their implications in the adoption of meritocracy as an organizational value. The research subjects were purposefully selected, among managers and career employees, and interviewed based on a script and from a photograph (photo elicitation) to reveal the current context. The field data were subjected to an inductive hermeneutic analysis. Based on these results, it can be inferred that meritocracy in career management, understood as ?a set of criteria, adopted by an organization that has on individual performance, effort and results, the fundamental pillars for granting promotions and progressions to its employees in their own careers?, is not yet explicitly manifested in the studied company. It was perceived that the company is set as a political arena type and that the current alternative process of granting promotions and progressions has been working as a fundamental mechanism for the on going internal power dynamics. On the context found, some manager actions were proposed to contribute to the implementation of meritocracy in career management. It can be considered, as a contribution to the field, the opportunity for reflecting on the negative implications of the penetration of management values in human resources, regarding: uncritical transfer of tools from the private sector to the public one; defense of entrepreneurship discourse that considers the career management as sole responsibility of the professional; only financial and quantitative focus on performance evaluations; and probability of management tools not resulting in professional development but only in the control and exploitation of the individual. For future research it is suggested i.e.: to investigate what commitment means to the organizational members in order to connect it to the company's concepts raised in the study; to analyze meritocracy from the psychological contract breach viewpoint; and to expand this study to other public organizations dependent or not on the Treasury, to ascertain the implications of cultural and managerial traits and the power dynamics for the adoption of meritocracy in career management.
A transforma??o da Administra??o P?blica Brasileira, no que tange ? ado??o de ferramentas modernas de gest?o de pessoas, vem ocorrendo desde o s?culo passado e a preocupa??o com a meritocracia na gest?o de carreira se configura como um assunto ainda recorrente. Como prova disso, destacam-se as orienta??es do ?rg?o de gest?o e controle das empresas estatais federais para que elas adotem a meritocracia nos seus sistemas de gest?o de carreira. A organiza??o aqui estudada, embora passados treze anos de vig?ncia do atual plano de cargos e sal?rios, parece ainda n?o ter conseguido instituir pol?ticas de gest?o de carreira calcadas na meritocracia. Diante do problema apresentado, o objetivo principal desta pesquisa se concentrou em levantar as implica??es dos tra?os provenientes do contexto organizacional de uma estatal federal brasileira, dependente do Tesouro Nacional, para a implanta??o da meritocracia na gest?o de carreira. Realizou-se pesquisa aplicada de natureza qualitativa, configurada em forma de estudo de caso ?nico para mapear os tra?os do contexto cultural, gerencial e pol?tico vigentes e interpretar suas implica??es na ado??o da meritocracia como um valor organizacional. Os sujeitos da pesquisa foram selecionados pelo m?todo proposital, entre gerentes e empregados de carreira, e entrevistados mediante roteiro e a partir de uma fotografia (elicita??o fotogr?fica) que revelasse o contexto vigente na ?tica dos mesmos. Os dados de campo foram qualitativamente analisados de forma hermen?utico-indutiva. Com base nos resultados obtidos, conclui-se que a meritocracia na gest?o de carreira, entendida como ?o conjunto de crit?rios, adotado por uma organiza??o, que possui no desempenho, no esfor?o individual e nos resultados alcan?ados os pilares fundamentais para a concess?o de promo??es e progress?es dos empregados em suas respectivas carreiras?, n?o ?, ainda, praticada explicitamente na empresa estudada. Revelou-se que a empresa se configura como uma organiza??o do tipo arena pol?tica e que o vigente processo alternativo de concess?o de promo??es e progress?es tem funcionado como um mecanismo fundamental na din?mica interna de poder. Diante deste contexto, foram propostas a??es de forma a contribuir com a implanta??o da meritocracia na gest?o de carreira. Considera-se como contribui??o ? ?rea a oportunidade de reflex?o sobre as implica??es da penetra??o de valores do management na gest?o de pessoas, relativas a: transfer?ncia acr?tica de ferramentas do setor privado para o p?blico; defesa do discurso do empreendedorismo, pressupondo a gest?o de carreira como responsabilidade unicamente do profissional; perspectiva apenas financeira e quantitativa das avalia??es de desempenho; e probabilidade das ferramentas de gest?o n?o resultarem no desenvolvimento profissional, mas no controle e explora??o do indiv?duo. Para aprofundamento em futuras pesquisas, sugere-se, dentre outras a??es: investigar o conceito de comprometimento na organiza??o, conectando-o ?s concep??es da Empresa levantadas no estudo; analisar a meritocracia a partir da ?tica da quebra do contrato psicol?gico; e expandir a presente pesquisa a outras organiza??es p?blicas dependentes ou n?o do Tesouro, a fim de evidenciar as implica??es dos tra?os culturais e gerenciais e da din?mica de poder existentes na ado??o da meritocracia na gest?o de carreira.
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Bruhat, Laure. „Microwaves as a probe of quantum dot circuits : from Kondo dynamics to mesoscopic quantum electrodynamics“. Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEE012/document.
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Cette thèse utilise les micro-ondes pour étudier des circuits de boîtes quantiques à base de nanotubes de carbone. Dans une première expérience, l'excitation micro-onde est appliquée directement sur une électrode du circuit pour une boîte quantique dans le régime Kondo. Nous réalisons la première caractérisation fréquence-amplitude de la conductance Kondo à biais nul. Des données préliminaires sont en accord avec la prédiction d'universalité. Nous présentons deux autres expériences, où les boîtes quantiques sont insérées dans des résonateurs micro-ondes. Les photons de la cavité sondent la résistance de relaxation de charge et l'émission de photons dans une boîte quantique couplée à des réservoirs normaux et supraconducteurs, en présence de répulsion coulombienne. Nos observations valident une modélisation en termes de réponse linéaire du circuit. Nous présentons aussi la première implémentation d'une lame séparatrice à paires de Cooper en cavité. Le régime de couplage fort est atteint, une première avec des circuits de boîtes quantiques. Nos résultats renforcent l'idée que l'électrodynamique quantique mésoscopique est une boîte à outils fructueuse, aussi bien dans le contexte du domaine du transport quantique que dans celui de l'information quantiqueThis thesis uses microwaves as probe of carbon nanotube quantum dot circuits. In a first experiment, a microwave excitation is directly applied to a circuit electrode for a quantum dot in the Kondo regime. We provide the first frequency-amplitude characterisation of the Kondo zero-bias conductance. Preliminary data are consistent with predicted universal behaviour. We present two other experiments, where quantum dot circuits are embedded in microwave resonators. Cavity photons probe charge relaxation resistance and photon-emission in a quantum dot coupled to normal and superconducting reservoirs in presence of Coulomb repulsion. Our observations validate a modelling in terms of the circuit linear response. We also present the first implementation of a Cooper pair splitter in cavity. The strong coupling regime is achieved, a premiere with quantum dot circuits. Our findings support the idea, that mesoscopic quantum electrodynamics is a fruitful toolbox in the context of both fields of quantum transport and quantum information science
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Chen, Wei-Hui, und 陳偉暉. „Quantum Molecular Dynamics Analysis on the Performance of Nanotube Photo-Electrochemical Solar Cells“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/60409239216537257675.
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Lan, Zhenggang [Verfasser]. „Photo-induced nonadiabatic dynamics of aromatic molecules via conical intersections : electronic-structure and time-dependent quantum dynamics calculations / Zhenggang Lan“. 2007. http://d-nb.info/985218819/34.
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Chien, Hao-Shen, und 簡豪伸. „Research on the Maintenance Strategy of Reconnaissance Photo-Equipmentfor Military Aircraft Using System Dynamics“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/surwkk.
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碩士育達科技大學
資訊管理所
105
Because the purchase of high-tech equipment by the Army is mostly from overseas for a small amount and D-Level repair is usually done by sending back to the foreign original equipment manufacturers, the time for relevant procedures and processes takes too long. Consequently, it is hard to maintain the availability. The purpose of this research aims to study the change of equipment availability, with Photo-Equipment as the subject. The relevant factors would be taken into account including working hours of equipment and the occupational stress derived from image processing. The objective of this research is to explore the dynamic situation of equipment availability under the different situations of maintenance time delay through the analysis of Vensim system dynamic simulation software. Via system dynamic model, however, most research which discussed the Photo-Equipment working hours, maintenance time delay, image process, staff work overload, and the availability of equipment has focused on the static situation. This research, from static perspective to dynamic perspective, could match the reality better and find the proper amount of Photo-Equipment to build suitable maintenance strategies.
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Zeman, Matthew Casimir. „In situ, real-time characterization of silicide nanostructure coarsening dynamics by photo-electron emission microscopy“. 2007. http://www.lib.ncsu.edu/theses/available/etd-05102007-101442/unrestricted/etd.pdf.
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LUO, LI-YANG, und 駱立揚. „Dynamics of Dye Sensitized Solar Cell: the Diffusion Rate of Photo-electrons in TiO₂ Nanotube“. Thesis, 2018. http://ndltd.ncl.edu.tw/handle/zyaky9.
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碩士朝陽科技大學
應用化學系
106
For studying the charge transfer process of array titanium oxide’s(ATO) microstructure, we measured measured the photovoltaic parameters with IV, IPCE, transient photocurrent and photovoltage under various TiO₂ tube length. In addition, the effects of dyeloading and thickness of electrolyte of ATO were also investigated. The diffusion rate and electron lifetimes are almost the same under similar length of TiO₂ tube. The molecular dyeloading desnity on TiO₂ surface influences the open-circuit voltage and electron lifetime, but the dyeloading does not influence the electron diffusion rate. When we modified the thickness of electrolyte, the thickness of electrolyte alters the distribution of density of trapped states and the potential of band edge on TiO₂. However, the thickness of electrolyte does not affect the diffusion rate. According to the prior results, the dyeloading and thickness of electrolyte don’t influence the electron diffusion rate. It is important to realize the dependance of diffusion rate and length of TiO₂ tube when the thick TiO₂ film generates the higher current density. The diffusion rate becomes faster on the longer TiO₂ tube under the same current density.
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Burmeister, Carl Friedrich. „Primary Effects of X-ray and Photo-Absorption Induced Excitations in Biomolecules“. Doctoral thesis, 2013. http://hdl.handle.net/11858/00-1735-0000-0001-B984-D.
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Huang, Chang-tai, und 黃章泰. „Resolving the dynamics of photo-induced phase transition of eumelanin by femtosecond pump-probe techniques using whitelight-generation probe pulse“. Thesis, 2008. http://ndltd.ncl.edu.tw/handle/23612475179636422570.
Annotation:
碩士國立中正大學
物理所
97
Eumelanin is one of the most ubiquitous biological pigments found in human body. Despite many decades of studies, people still do not have a complete picture of its macromolecular structure. Since eumelanin has a well-known, broad-band monotonic absorption, studying the dynamics of light absorption becomes an important method to investigate the structure of eumelanin. From the degenerate UV pump-probe experiment by Simon et al., the optical absorption spectrum of the monomer and tetramer composing of four monomers found to be quite different is quite different. We use the whitelight-generation pulse as probe beam to perform the femtosecond pump-probe experiment to explore the structure dynamics of eumelanin. In chapter 1, we introduce the structure of eumelanin and review the related experiment in the past. In chapter 2, we describe the laser system, the experimental setup and parameters used in the experiment. In charpter 3, we show the experiment results and propose an appropriate model to explain the data. The last chapter is the conclusion of this study and possible follow-up works.
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Ronge, Emanuel. „In-Situ Environmental TEM Studies of Electro- and Photo-Electrochemical Systems for Water Splitting“. Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-157D-8.
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Praneeth, N. V. S. „Development of Gold and Gold/semiconductor Nanostructures for Plasmonic and Photo/Electro-Catalytic Applications“. Thesis, 2021. http://ethesis.nitrkl.ac.in/10368/1/2022_PhD_N.V.S.Praneeth_512CH1009_Development.pdf.
Annotation:
A simple, scalable one-pot synthesis route for ‘highly active’ Au nanoparticles (NPs) using oxalic acid (OA) as reducing agent was developed. At [Au3+]:[OA] of 1:3 under 50 C and microwave heating yielded highly active {110} facet exposed rhombic and squashed dodecahedron NPs (R&SD). Kinetics and mechanism of formation were studied in detail. The catalytic activity of these NPs were tested for 4-nitrophenol hydrogenation. Also, metal enhanced fluorescence (MEF) and 1O2 generation (MESOG) of bioactive Rose Bengal (RB) dye by these NPs were studied. The hydrogenation rate was almost double, MEF increased 5 times and MESOG generation increased significantly for R&SD compared to other shaped NPs. Such high plasmonic activity owns to electromagnetic field enhancement (hot-spots) at sharp edges and corners of Au NPs. For stable, long term use of NPs, they were loaded on natural kaolinite clay. They showed high activity in catalytic hydrogenation of 4-nitrophenol, SERS signal enhancement of RB. Similarly, kaolinite-TiO2 (KT) composite were successfully prepared by OA catalyzed sol-gel method and co-doped with N, S (KTN,S). TiO2 NPs of 5-10 nm got deposited uniformly over clay. Also, presence of electrolyte (E) and Au NPs on KT (AKT) on photocatalytic activity were tested. The methylene blue degradation efficiency for various catalysts were of the following order, P25
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„Soot Black Carbon Dynamics in Arid/urban Ecosystems“. Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.20912.
Annotation:
abstract: Black carbon (BC) is the product of incomplete combustion of biomass and fossil fuels. It is found ubiquitously in nature and is relevant to studies in atmospheric science, soil science, oceanography, and anthropology. Black carbon is best described using a combustion continuum that sub-classifies BC into slightly charred biomass, char, charcoal and soot. These sub-classifications range in particle size, formation temperature, and relative reactivity. Interest in BC has increased because of its role in the long-term storage of organic matter and the biogeochemistry of urban areas. The global BC budget is unbalanced. Production of BC greatly outweighs decomposition of BC. This suggests that there are unknown or underestimated BC removal processes, and it is likely that some of these processes are occurring in soils. However, little is known about BC reactivity in soil and especially in desert soil. This work focuses on soot BC, which is formed at higher temperatures and has a lower relative reactivity than other forms of BC. Here, I assess the contribution of soot BC to central AZ soils and use the isotopic composition of soot BC to identify sources of soot BC. Soot BC is a significant (31%) fraction of the soil organic matter in central AZ and this work suggests that desert and urban soils may be a storage reservoir for soot BC. I further identify previously unknown removal processes of soot BC found naturally in soil and demonstrate that soil soot BC undergoes abiotic (photo-oxidation) and biotic reactions. Not only is soot BC degraded by these processes, but its chemical composition is altered, suggesting that soot BC contains some chemical moieties that are more reactive than others. Because soot BC demonstrates both refractory and reactive character, it is likely that the structure of soot BC; therefore, its interactions in the environment are complex and it is not simply a recalcitrant material.Dissertation/Thesis
Ph.D. Chemistry 2013