Thèses : « Photons migration »

1

Saarela, J. (Juha). « Photon migration in pulp and paper ». Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514275845.

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Abstract The thesis clearly demonstrates that photon migration measurements allow characterization of pulp and paper properties, especially the fines and filler content of pulp, and the basis weight, thickness and porosity of paper. Pulp and paper are materials with a worldwide significance. Their properties strongly depend on the manufacturing process used. For efficient process control, the employed monitoring and measuring has to be fast. Therefore it is worthwhile to try to develop new approaches and techniques for such measurements. Recent advancements in optics offer new possibilities for such development. If two samples have different optical properties their photon migration distributions are different. The measurement of a photon migration distribution allows some features between two optically slightly dissimilar samples to be distinguished. Some simple measurements, which only yielded the photons' average time of flight, were made with an oscilloscope and a time-of-flight lidar. More precise measurements yielding photon pathway distribution or some selected characteristics like light pulse rise time, broadening, or fall time were measured with a streak camera. Two methods to assess photon path length distribution were introduced: particle determination with simulation, and streak camera with deconvolution. The basic properties for pulp are consistency and fines content and for paper the basic properties are thickness, basis weight and porosity. The influence on photon migration caused by changes in these basic properties was determined. As pulp and paper are rarely very basic, an additional property was demonstrated for both materials. For pulp it was the content of filler talc, and for paper it was the use of beaten pulp as a raw material. These additional properties were also distinguishable.

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2

Huang, Yingqing. « Characterization of dense suspensions using frequency domain photon migration ». Texas A&M University, 2003. http://hdl.handle.net/1969.1/2207.

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Interparticle interactions determine the microstructure, stability, rheology, and optical properties of concentrated colloidal suspensions involved in paint, paper, cosmetic, and pharmaceutical industries, etc. Frequency domain photon migration (FDPM) involves modeling the photon transport in a multiple scattering medium as a diffusion process in order to simultaneously determine isotropic scattering and absorption coefficients from measured amplitude attenuation and phase shift of the propagating photon density wave. Using FDPM, we investigated the impact of electrostatic interaction upon the optical properties and structure of dense charged suspensions. We demonstrated that electrostatic interactions among charged polystyrene latex may significantly affect the light scattering properties and structure of dense suspensions at low ionic strength (<0.06 mM NaCl equivalent) by actual FDPM measurement. We showed that the structure factor models addressing electrostatic interaction can be used to describe the microstructure of charged suspensions and quenched scattering due to electrostatics, and demonstrated that FDPM has the potential to be a novel structure and surface charge probe for dense suspensions. We also showed that the FDPM measured isotropic scattering coefficients may respond to the change in effective particle surface charge, and displayed the potential of using FDPM for probing particle surface charge in concentrated suspensions. We presented that the interference approximation implies a linear relationship between the absorption coefficient and volume fraction of suspension. We illustrated that FDPM measured absorption coefficient varies linearly with suspension volume fraction and affirmed the interference approximation from a perspective of light absorption. The validation of the interference approximation enables us to develop the methodology for estimating absorption efficiencies and imaginary refractive indices for both particles and suspending fluid simultaneously using FDPM. We further demonstrated a novel application of FDPM measured absorption coefficients in determining pigment absorption spectra, and displayed the potential of using FDPM as a novel analytical tool in pigment and paint industry.

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3

Xu, Zhoujia. « Migration from electronics to photonics in multicore processor ». Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45394.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.
Includes bibliographical references (leaf 54).
Twenty - first opportunities for Gigascale Integration will be governed in part by a hierarchy of physical limits on interconnect. Microprocessor performance is now limited by the poor delay and bandwidth performance of the on - chip global wiring layer. This thesis is envisioned as a critical showstopper of electronic industry in the near future. The physical reason behind the interconnect bottleneck is the resistive nature of metals. The introduction of copper in place of aluminum has temporarily improved the interconnect performance, but a more disruptive solution will be required in order to keep the current pace of progress, optical interconnect is an intriguing alternative to metallic wires. Many - core microprocessors will push performance per chip from the 10 gigaflop to the 10 teraflop range in the coming decade. Pin limitations, the energy cost of electrical signaling, and the non - scalability of chip - length global wires are significant bandwidth impediments. Silicon nanophotonic based many core architecture are introduced in order to meet the bandwidth requirements at acceptable power levels.
by Zhoujia Xu.
M.Eng.

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4

Pan, Tianshu. « Application and modeling of near-infrared frequency domain photon migration for monitoring pharmaceutical powder blending operations ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/4433.

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Frequency domain photon migration consists of launching an intensitymodulated near-infrared light into the powder medium and measuring the amplitude, mean-intensity, and phase shift of detected intensity modulated light for extracting both the isotropic scattering and absorption coefficients of the powder bed. The dependence of absorption coefficient upon the active pharmaceutical ingredient (API) concentration of powder blend enables FDPM to monitor blending homogeneity. The volume sampled by FDPM in powder blend was investigated through a designed heterogeneity experiments. A model which describes the visitation probability of a local region by migrating photons was developed to theoretically determine the sampled volume of FDPM in terms of signal-to-noise ratio. The applicability of FDPM in monitoring blending homogeneity was directly verified by measuring the API contents in a series of industrial samples, which were retrieved from various locations at various times in an actual pharmaceutical blending process. The FDPM measurement results were consistent with the traditional analysis using high performance liquid chromatography. The homogeneity evolution revealed through FDPM agreed with the well-established first order model of blending. A simulation method was developed which consisted of (i) dynamic simulation for generating the powder structure; (ii) the completely-randommixture model for predicting the spatial distribution of API particles within the powder bed; and (iii) Monte Carlo simulation for tracking photon trajectories within the powder bed. The simulation of photon migration in powder blend revealed that while both the isotropic scattering and absorption coefficients increased with the solid-volume fraction, the ratio of absorption coefficient to the isotropic scattering coefficient is (i) independent of the solid-volume fraction; (ii) linearly dependent upon the API concentration; and (iii) appropriate for monitoring the powder blending homogeneity under simultaneous variations of solid-volume fraction and API content. Finally, a rigorous two-speed diffusion equation for describing photon migration in powders was derived from the two-group radiative transfer equations and the analytical expression of the isotropic scattering coefficient was provided. The theoretical results agreed well with the experimental measurements in resin powder media and resin suspensions.

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5

Dali, Sarabjyot Singh. « Analysis of dense colloidal dispersions with multiwavelength frequency domain photon migration measurements ». [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1751.

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6

Houston, Jessica Perea. « Near infrared optical lymphography for cancer diagnostics ». Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4807.

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A new molecular imaging modality has been developed to detect and locate positive axillary and sentinel lymph nodes non-invasively in breast cancer patients undergoing lymphoscintigraphy. The modality is based on fluorescent photon detection to locate the presence of indocyanine green (ICG) in the lymph subsequent to peritumoral injection of ICG into the breast. The imaging system consists of a gain-modulated intensified charge-coupled device (ICCD) camera, which captures low-intensity, near-infrared, and frequency-modulated photons. A four-fold Ã¢ÂÂoptical lymphographyÃ¢ÂÂ study was conducted to (1) examine fluorescence depth penetration and ICCD system accuracy at clinically relevant depths, (2) compare image quality of the ICCD system vs. conventional gamma imaging, (3) measure ICG pharmacokinetics in vivo, and (4) develop a clinical protocol while examining pre-clinical factors such as the outcome of combining ICG with sulfur colloids used in lymphoscintigraphy. The frequency-domain ICCD system was found to precisely detect modulation amplitude, IAC, and phase, ÃÂ¸, at depths up to 9 cm and with IAC accuracy less than 20% and ÃÂ¸ less than 2ÃÂº using an 80-mW laser incident on phantoms having ranging tissue optical properties. Significant differences in the mean depth of penetration owing to 0.62-ns lifetime and 100-MHz frequency increases were detected. An in vivo optical vs. nuclear image quality comparison demonstrated statistically similar (ÃÂ±=0.05) target-to-background ratios for optical (1.4+/-0.3) and nuclear (1.5+/-0.2). Alternatively, resulting image signal-to-noise ratios (SNR) from the ICCD system were greater than that achieved with a conventional gamma camera (pvalue<<0.01). Analysis of SNR versus contrast showed greater sensitivity of optical over nuclear imaging for subcutaneous tumors. In vivo and rapid detection of ICG in the blood-stream of nude mice was accomplished with a home-built avalanche photodiode dynamic fluorescence measurement system. Intensity data upon i.v. injection were regressed with a pharmacokinetic model describing the partitioning of ICG from the blood to the surrounding tissues. ICG blood-clearance was detected approximately 15 min after injection. Lastly, a human subject protocol was written, practiced, and federally approved for the application of optical lymphography. Furthermore, ICG was unaffected when mixed with sulfur colloids thus supporting the feasibility for combining fluorescence imaging with lymphoscintigraphy in breast cancer patients.

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7

Wu, Jun 1968. « Photon migration in turbid media : time-resolved optical imaging in tissue-like phantom ». Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10792.

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8

Mikaelsson, Therese. « Electronic Energy Migration/Transfer as a Tool to Explore Biomacromolecular Structures ». Doctoral thesis, Umeå universitet, Kemiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-86794.

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Fluorescence-based techniques are widely used in bioscience, offering a high sensitivity and versatility. In this work, fluorescence electronic energy migration/ transfer is applied to measure intramolecular distances in two types of systems and under various conditions. The main part of the thesis utilizes the process of donor-acceptor energy transfer to probe distances within the ribosomal protein S16. Proteins are essential to all organisms. Therefore, it is of great interest to study protein structure and function in order to understand and prevent protein malfunction. Moreover, it is also important to try to study the proteins in an environment which resembles its natural habitat. Here two protein homologs were investigated; S16Thermo and S16Meso, isolated from a hyperthemophilic bacterium and a mesophilic bacterium, respectively. It was concluded that the chemically induced unfolded state ensemble of S16Thermo is more compact than the corresponding ensemble of S16Meso. This unfolded state compaction may be one reason for the increased thermal stability of S16Thermo as compared to S16Meso. The unfolded state of S16 was also studied under highly crowded conditions, mimicking the environment found in cells. It appears that a high degree of crowding, induced by 200 mg/mL dextran 20, forces the unfolded state ensemble of S16Thermo to become even more compact. Further, intramolecular distances in the folded state of five S16 mutants were investigated upon increasing amounts of dextran 20. We found that the probed distances in S16Thermo are unaffected by increasing degree of crowding. However, S16Meso shows decreasing intramolecular distances for all three studied variants, up to 100 mg/mL dextran. At higher concentrations, the change in distance becomes anisotropic. This suggests that marginally stable proteins like s16Meso may respond to macromolecular crowding by fine-tuning its structure. More stable proteins like S16Thermo however, show no structural change upon increasing degree of crowding. We also investigated the possibility of local specific interactions between the protein and crowding agent, by means of fluorescence quenching experiments. Upon increasing amounts of a tyrosine labelled dextran, a diverse pattern of fluorescence quantum yield and lifetime suggests that specific, local protein-crowder interactions may occur. In a second studied system, electronic energy migration between two donor-groups, separated by a rigid steroid, was studied by two-photon excitation depolarization experiments. Data were analysed by using recent advances, based on the extended Förster theory, which yield a reasonable value of the distance between the two interacting donor-groups. To the best of our knowledge, this is the first quantitative analysis of energy migration data, obtained from two-photon excited fluorescence.

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Gesta, Emmanuelle. « Study of the interaction and migration mechanisms in the systems polymer/insecticide ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1093.

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Le principal objectif des travaux présentés dans ce manuscrit était d’étudier certains paramètres régissant l’efficacité et la durabilité de moustiquaires avec des molécules insecticides incorporées dans les fils de polyéthylène. Pour cela deux axes de travail ont été identifiés : l’étude des phénomènes de migration des molécules insecticide dans les fils de polyéthylène et l’étude des mécanismes de photo-dégradation de l’insecticide étudié : la deltaméthrine.L’étude de l’influence du procédé de fabrication des moustiquaires sur la morphologie du polyéthylène a permis de montrer que l’étape d’étirage à froid était critique dans la définition des propriétés morphologiques (cristallinité et orientation de la structure cristalline) et mécaniques des fils. L’effet du recuit observé est plus modéré (légère augmentation de l’épaisseur des lamelles cristallines). Néanmoins, il a été montré que les modifications induites par le recuit sur la morphologie du polyéthylène ont une influence sur les phénomènes de migration des molécules insecticides dans les fils. En effet, alors qu’un retard est observé dans les courbes de désorption des fils non recuits, ce retard disparaît pour les fils recuits. Il a été également montré que la faible vitesse d’évaporation de la deltaméthrine permet de limiter la migration de la deltaméthrine hors des fils.L’étude de la photo-dégradation de la deltaméthrine a permis de mettre en évidence les principaux mécanismes de dégradation (isomérisation, scission de la fonction ester et de la fonction cyclopropane). L’ajout d’additifs de type antioxydants ou filtres UV permet de limiter la vitesse de dégradation de la deltaméthrine
The main objective of the works presented in this manuscript was to study some of the parameters ruling the efficacy and the durability of the mosquito nets with incorporated insecticide in the polyethylene yarns. To achieve this goal, two lines of research were identified: the study of the insecticide migration phenomena in the yarns and the study of the photodegradation mechanisms of the molecule of interest: the deltamethrin.The study of the influence of the nets fabrication process on the polyethylene morphology showed that the cold-drawing step was critical to define the morphological (crystallinity and orientation of the crystalline structure) and mechanical properties. The observed influence of the heat-setting appeared less important (slight increase of the crystalline lamellae thickness). However, the heat-setting induced modifications which affected the migration of the insecticide molecules in the yarns. Indeed, while a delay is observed in the desorption curves of the non-heat-set yarns, this time-lag disappeared in the heat-set yarns. It was also shown that the low evaporation rate of deltamethrin permits to impede the migration of deltamethrin out of the yarns.The study of the photodegradation of deltamethrin permitted to highlight the main degradation mechanisms (isomerization, ester cleavage and cyclopropane cleavage). Antioxidant and UV absorber additives can be used to reduce the deltamethrin degradation rate

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Rasmussen, John C. « Development of a radiative transport based, fluorescence-enhanced, frequency-domain small animal imaging system ». Thesis, [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1067.

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Gurfinkel, Mikhail. « Cancer diagnostics using dynamic near-infrared optical imaging and fluorescent contrast agents ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/3162.

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A new optical imaging modality has been developed for small animal in vivo imaging of near-infrared fluorescence resulting from fluorescent contrast agents specifically targeted to molecular markers of cancer. The imaging system is comprised of an intensified charge-coupled device (ICCD) for the detection of ultra-low levels of re-emitted fluorescence following the delivery of an expanded beam of excitation light. The design of the ICCD detection system allows for both continuous wave (CW) and frequency-domain modes of operation. Since the accurate acquisition of frequency-domain photon migration (FDPM) data is important for tomographic imaging, the imaging system was also validated using experimentally obtained FDPM measurements of homogenous turbid media and diffusion theory to obtain estimates of the optical properties characteristic of the media. The experiments demonstrated that the absorption and reduced scattering coefficients are determined least accurately when relative rel measurements of average light intensity IDC are employed either alone or in a rel combination with relative modulation amplitude data IAC and/or relative phase shift data rel . However, when FDPM measurements of are employed either alone or in rel combination with IAC data, the absorption and reduced scattering coefficients may be found accurate to within 15% and 11%, respectively, of the values obtained from standard single-pixel measurements; a result that suggests that FDPM data obtained from an ICCD detection system may in fact be useful in tomographic imaging. Furthermore, intensified-detection allows for sub-second exposure times, permitting the acquisition of dynamic fluorescence images immediately following administration of the contrast agent. Experimental results demonstrate that when coupled with a suitable pharmacokinetic model describing targeted dye distribution throughout the body, dynamic fluorescence imaging may be used to discriminate spontaneous canine adenocarcinoma from normal mammary tissue. A separate experiment demonstrates that pharmacokinetic analysis of dynamic fluorescence images enables one to estimate the rate constant governing Kaposi's sarcoma tumor uptake of an integrin-targeted dye and integrin receptor turnover rate. The rate constant for uptake was calculated to be 0.16-sec-1 while the turnover rate of the integrin receptor was estimated to occur within 24-hours.

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Lissau, Jonas Sandby. « Non-Coherent Photon Upconversion on Dye-Sensitized Nanostructured ZrO2 Films for Efficient Solar Light Harvesting ». Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229831.

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Photon upconversion by sensitized triplet–triplet annihilation (UC-STTA) is a photophysical process that facilitates the conversion of two low-energy photons into a single high-energy photon. A low-energy photon is absorbed by a sensitizer molecule that produces a triplet excited state which is transferred to an emitter molecule. When two emitter triplet states encounter each other, TTA can take place to produce a singlet excited state which decays by emission of a high-energy (upconverted) photon. While traditional single-threshold dye-sensitized solar cells (DSSCs) have a maximum efficiency limit of ca. 30%, it has been predicted theoretically that implementation of UC-STTA in DSSCs could increase that efficiency to more than 40%. A possible way to implement UC-STTA into DSSCs, would be to replace the standard sensi- tized nanostructured TiO2 photoanodes by upconverting ones loaded with emitter molecules. Following TTA, the excited emitter molecule would be quenched by injection of a high-energy electron into the conduction band of the TiO2. To explore the practical aspects of this strategy for a highly efficient DSSC, in this thesis UC-STTA is studied in model systems based on nanostructured ZrO2 films. These ZrO2 films are a good proxy for the TiO2 films used in DSSCs, and allow for relatively easy optimization and study of UC-STTA by allowing measurements of the upconverted photons without the complications of electron injection into the film. Herein it is experimentally proven that UC-STTA is viable on nanostructured metal oxide films under non-coherent irradiation with intensities comparable to sunlight. Two different system architectures are studied, differing in the position of the molecular components involved in the UC-STTA mechanism. Both architectures have the emitter molecules adsorbed onto the ZrO2 surface, but the sensitizers are positioned either in solution around the nanostructure, or co-adsorbed with the emitters onto the ZrO2 surface. A set of challenges in the study and optimization of the UC-STTA process is identified for each type of system. Proposals are also given for how to further improve the understanding and UC-STTA optimization of these systems toward application in DSSCs to overcome the present solar energy conversion efficiency limit.

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Ryderfors, Linus. « Two-Photon Excited Fluorescence Depolarisation : Experimental and Theoretical Development ». Doctoral thesis, Uppsala University, Department of Photochemistry and Molecular Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9285.

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We have studied fundamental aspects of time-resolved two-photon excited fluorescence depolarisation. The thesis presents experimental as well as theoretical progress. We show that a multi-photon induced instrumental response function obtained from a suspension of gold nanoparticles is appropriate for the analysis of two-photon excited fluorescence decays obtained using time-correlated single photon counting detection. Theoretical expressions have been derived for the fluorescence anisotropy decay obtained upon two-photon excitation of various molecular systems in liquid solutions: a) an anisotropic rigid rotor that undergoes rotational diffusion in the presence of ultrafast unresolved restricted reorientations, e.g. librations. b) a molecular group covalently attached to a stationary macromolecule, and undergoing local reorientation in a uniaxial ordering potential. A new approach to the analysis of two-photon excited fluorescence depolarisation experiments was developed, which combines data obtained by using linearly and circularly polarised excitation light, in a global manner. In the analysis, knowledge about unresolved reorientations was obtained from one-photon excitation studies of the corresponding systems. By means of this procedure it has been possible to obtain quantitative information about the molecular two-photon absorption tensor for perylene and two of its derivatives. Thereby the symmetry of the final excited and intermediate vibronic states could be assigned. The analysis reveals that the two-photon transition studied with the 800 nm laser exhibits mixed character. An important finding from the experiments was that the two-photon absorption tensor appears to be solvent dependent. Furthermore, the thesis presents the first theoretical treatment of two-photon excited donor-donor energy migration in the presence of molecular reorientation and which applies the extended Förster theory. Explicit expressions for molecules that belong to the point groups D_2h, D₂ and C_2v are given. Preliminary experiments are finally also reported on a two-photon excited donor-donor energy migration system consisting of a bisanthryl-bisteroid.

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Hubert, Christophe. « PROCESSUS DE MIGRATION MOLECULAIRE PHOTO-INDUITE EN MILIEU POLYMERE. APPLICATION A LA REALISATION DE NANOSTRUCTURES ORGANISEES OPTIQUEMENT ». Phd thesis, Université Paris Sud - Paris XI, 2003. http://tel.archives-ouvertes.fr/tel-00111028.

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Ce travail de thèse porte sur l'étude d'un nouveau processus de structuration tout optique de films polymères azoïques. Nous mettons en évidence que l'irradiation en incidence normale d'un film polymère azoïque par un faisceau laser d'intensité uniforme dont la longueur d'onde est comprise dans la bande d'absorption du chromophore, peut conduire à la création de nano-structures organisées sous la forme d'un réseau de surface quasi-hexagonal à la surface du film polymère.
Après un rappel des méthodes classiques de micro et nanostructuration ainsi que des propriétés des polymères azoïques dans le cadre de la création de réseaux de surface, la première partie du manuscrit est consacrée à l'étude de l'influence de divers paramètres expérimentaux sur la formation spontanée de ces structures, parmi lesquels la polarisation du faisceau d'écriture ou bien encore la puissance d'irradiation. Une comparaison des résultats obtenus dans notre cas avec différents processus de structuration photo-assistés déjà étudiés et dont les origines physiques sont clairement établies est ensuite effectuée, ceci afin de déterminer les paramètres clefs gouvernant la création de ces structures hexagonales en même temps que leurs origines.
Dans une seconde partie, une synthèse des différentes expériences réalisées en vue d'évaluer la validité d'effets dits de « feedback optique » tels que ceux observés dans des systèmes de valves à cristaux liquides est effectuée. Ceci a permis de mettre en évidence la difficulté d'interprétation du processus de structuration hexagonal photoinduit : il n'est pas exclu qu'un phénomène de feedback optique soit à l'origine du processus de structuration, mais dans l'état actuel des différentes expériences ayant pu être menées, un phénomène nouveau et original de structuration propre aux polymères azoïques ne peut être écarté afin d'expliquer totalement les différents résultats obtenus.
Enfin, la dernière partie de ce travail est consacrée à la mise en oeuvre de ces structures hexagonales dans des dispositifs photoniques et plus particulièrement dans des diodes électroluminescentes organiques, ceci afin de contrôler leurs propriétés d'émission. Il est notamment démontré que dans le cas d'un pompage optique, due à la diffraction de Bragg, il est possible d'augmenter le rendement d'émission de tels dispositifs en découplant une partie de la lumière initialement guidée dans les différentes couches de la diode. Due à l'orientation hexagonales des structures, l'augmentation du rendement apparaît comme étant plus importante que celle obtenue lors de l'utilisation d'un réseau unidimensionnel.

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Hubert, Christophe. « Processus de migration moléculaire photo-induite en milieu polymère : application à la réalisation de nanostructures organisées optiquement ». Paris 11, 2003. https://tel.archives-ouvertes.fr/tel-00111028.

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Ce travail de thèse porte sur l'étude d'un nouveau processus de structuration tout optique de films polymères azoi͏̈ques. Nous mettons en évidence que l'irradiation en incidence normale. D'un film polymère azoi͏̈que par un faisceau laser uniforme dont la longueur d'onde est comprise dans la bande d'absorption de ce dernier, peut conduire à la création de nano-structures organisées sous la forme d'un réseau de surface quasi-hexagonal a la surface du film polymère. Apres un rappel, des méthodes classiques de micro et nanostructuration ainsi que des propriétés des polymères azoi͏̈ques dans le cadre de la création de réseaux de surface, la première partie du manuscrit est consacrée a l'étude de l'influence de divers paramètres expérimentaux sur la formation spontanée contrôlée optiquement de ces structures, parmi lesquels la polarisation du faisceau d'écriture ou bien encore la puissance d'irradiation. Une comparaison des résultats obtenus dans notre cas avec différents processus de structuration photo-assistés déjà proposés et dont les origines physiques sont clairement établies est ensuite effectuée, ceci afin de déterminer les paramètres clefs gouvernant la création de ces structures hexagonales en même temps que leurs origines. Dans une seconde partie, une synthèse des différentes expériences réalisées en vue d'évaluer la validité d'effets dits de "feedback optique" tels que ceux observes dans des systèmes de valves a cristaux liquides est effectuée. Ceci a permis de mettre en évidence la difficulté d'interprétation du processus de structuration hexagonal photoinduit : il n'est pas exclu qu'un phénomène de feedback optique soit a l'origine du processus de structuration, mais dans l'état actuel des différentes expériences ayant pu être menées, un phénomène nouveau et original de structuration propre aux polymères azoi͏̈ques ne peut être écarté afin d'expliquer totalement les différents résultats obtenus
This work deals with the study of a new all optical structuration process of azo-polymer films. We show that the irradiation with normal incidence of an azo-polymer film by a uniform laser beam which wavelength is in the absorption band of the azo-molecules, can lead to the formation of a quasi hexagonal surface relief grating at the surface of a polymer film. After a brief review of different methods of micro and nanostructuration as well as the properties of azo-polymer films in the case of the surface relief gratings formation, we study in the first part of this manuscript the influence of several experimental parameters on the spontaneous optically controlled formation of these photoinduced structures, among them the light polarization direction and the irradiation power. The different results obtained in our case are then compared with different photo-assisted structuration processes already proposed and whose physical origins are clearly established, in order to determine the key parameters governing the formation of these hexagonal structures as well as their origins. In the second part, a synthesis of the different experiments performed in order to evaluate the validity of effects so called "optical feedback effect" observed in liquid crystal light valve systems is performed. The interpretation of the photoinduced hexagonal structuration process appears to be difficult: it is not excluded that an optical feedback phenomenon could be at the origin of the structuration process, but at the present, according to the different experiments performed, a new and original phenomenon of structuration adapted to azo-polymers films cannot be excluded in order to fully explain the different results obtained

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Hubert, Christophe. « Processus de migration moléculaire photo-induite en milieu polymère, application à la réalisation de nanostructures organisées optiquement / ». Gif-sur-Yvette : CEA Saclay, Direction des systèmes d'information, 2003. http://catalogue.bnf.fr/ark:/12148/cb39167457s.

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Guiet, Romain. « Étude des mécanismes cellulaires et moléculaires de la migration des macrophages humains dans des environnements en trois dimensions ». Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1487/.

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L'infiltration tissulaire des macrophages est un facteur aggravant dans de nombreuses pathologies telles que les maladies inflammatoires chroniques ou le cancer. Les macrophages qui infiltrent les tumeurs de façon continue sont appelés macrophages associés aux tumeurs (TAMs). Ils favorisent la croissance tumorale, l'angiogenèse, l'invasion tumorale et la formation de métastases. L'inhibition de l'infiltration des macrophages est donc devenue une évidence thérapeutique. Récemment, l'équipe a démontré que les macrophages utilisent le mode migratoire amiboïde (dépendant de ROCK) ou mésenchymal (dépendant des protéases) selon l'architecture de la matrice extracellulaire (MEC) en trois-dimensions (3D) qu'ils traversent. De plus, l'étude du mode migratoire mésenchymal a montré qu'il est dépendant de Hck (une tyrosine kinase spécifique des phagocytes) et de sa capacité à réorganiser les podosomes en rosettes (structures riches en actine dégradant la MEC). Mon projet de thèse s'est articulé autour de deux axes de recherche : 1) l'identification des substrats de Hck et la caractérisation de leur rôle dans l'organisation des podosomes et la migration 3D des macrophages, et 2) l'étude de la migration 3D des monocytes/macrophages primaires humains dans un modèle mimant le microenvironnement tumoral : les sphéroïdes tumoraux. Par une approche protéomique j'ai identifié des partenaires et substrats potentiels de Hck dont la Filamine A (FLNa), une protéine assurant notamment la liaison entre le cytosquelette d'actine et les intégrines. En utilisant différents outils (protéines recombinantes, anticorps, shRNA. . . ) j'ai montré que : 1) Hck phosphoryle la FLNa in vitro, 2) la FLNa est associée aux podosomes et est nécessaire à leur organisation en rosettes sous le contrôle de Hck, 3) les podosomes des cellules déficientes en Flna ont une durée de vie plus courte, et 4) l'expression de la FLNa est nécessaire à la migration mésenchymale, mais pas à la migration amiboïde des macrophages dans une MEC en 3D. Ainsi la FLNa est impliquée dans la formation et à la stabilisation des podosomes, à leur organisation en rosettes, la migration mésenchymale des macrophages et pourrait se situer dans la voie de signalisation de Hck. En parallèle, j'ai mis au point un modèle de sphéroïdes tumoraux qui m'a permis de montrer que l'infiltration des monocytes ou des macrophages, dans ce modèle tissulaire in vitro, est dépendante de ROCK et des protéases, signature de l'utilisation des deux modes migratoires. Puis en incubant ces sphéroïdes au sein de MEC, j'ai démontré que la présence de macrophages infiltrés dans les sphéroïdes est nécessaire pour déclencher le pouvoir invasif des cellules tumorales qui émigrent des sphéroïdes en suivant les macrophages et infiltrent la MEC environnante. Les macrophages Hck-/- présentant un défaut de migration mésenchymale, sont significativement moins efficaces dans la promotion de l'invasion des cellules tumorales. Ces résultats indiquent que l'activité de migration et de remodelage de la matrice exercée par les macrophages est prépondérante dans l'invasion tumorale in vitro. Ces résultats ont permis d'établir le mode migratoire des macrophages infiltrant un modèle tissulaire in-vitro et de démontrer le mécanisme d'action des macrophages dans l'invasion tumorale. Ainsi, mes travaux de thèse ont permis de progresser dans la caractérisation des mécanismes moléculaires et cellulaires de la migration 3D des macrophages humains. En effet, j'ai pu 1) identifier une protéine nécessaire à la migration mésenchymale des macrophages, 2) mettre en évidence l'utilisation par les macrophages des modes migratoires amiboïde et mésenchymal lors de leur infiltration dans un modèle de tumeur en trois-dimensions, les sphéroïdes tumoraux et 3) montrer que le remodelage de la matrice par les macrophages, lors de leur migration, joue un rôle prépondérant dans l'invasion tumorale
Tissue infiltration of macrophages is an aggravating factor in many diseases such as chronic inflammation and cancer. Macrophages that infiltrate tumors are called tumor-associated macrophages (TAMs). They promote tumor growth, angiogenesis, invasion and metastasis. Thus, inhibition of macrophage infiltration has become a therapeutic goal. Recently, the team demonstrated that macrophages use the amoeboid (depending on ROCK) or the mesenchymal (depending on proteases) migratory mode according to the extracellular matrix (ECM) architecture in three dimensions (3D). In addition, the study of the mesenchymal migration mode showed that it is dependent on Hck (a phagocyte-specific tyrosine kinase) and its ability to reorganize podosomes (ECM-degrading actin-rich structures) into rosettes. My thesis project was organized around two axes 1) the identification of substrates of Hck and the characterization of their role in the organization of podosomes and 3D migration of macrophages, and 2) the study of the 3D migration mechanisms of primary human monocytes/ macrophages within an in vitro tumor model: tumor cell spheroids. By a proteomic approach, I have identified potential partners and substrates of Hck, including the protein Filamin A (FLNa), a protein interacting with the actin cytoskeleton and integrins. Using different tools (recombinant proteins, antibodies, shRNA. . . ) I showed that: 1) Hck phosphorylates FLNa in vitro, 2) FLNa is localized to podosomes and is necessary for their organization as rosettes under the control of Hck, 3) the podosomes of FLNa-deficient cells have a shorter life span, and 4) the expression of FLNa is required for mesenchymal migration, but not for amoeboid migration of macrophages in a 3D ECM. Thus, FLNa could be a substrate of Hck necessary for the formation and stabilization of podosomes and their organization as rosettes, and is required for the mesenchymal migration of macrophages. In parallel, I developed a model of tumor cell spheroids, which allowed me to show that the infiltration of monocytes or macrophages in this in vitro tissue model of tumor is dependent on ROCK and proteases, signature of the use of the two migration modes. Then, when spheroids were embedded into ECM, I demonstrated that the presence of macrophages infiltrated into the spheroids is necessary to trigger the invasiveness of tumor cells. Indeed, macrophages infiltrate first the surrounding ECM and tumor cells follow macrophages in the matrix outside of the spheroid. Hck-/- macrophages, that are defective in mesenchymal migration, are significantly less effective in promoting the invasion of tumor cells. These results indicate that the activity of migration and matrix remodeling exerted by macrophages is prominent in tumor invasion. These results have established the migratory mode of macrophages infiltrating an in vitro tumor model and a mechanism required for tumor invasiveness promoted by macrophages. Thus during my thesis, I characterized the molecular and cellular mechanisms of 3D migration of human macrophages. Indeed, I have been able to: 1) identify a protein necessary for the mesenchymal migration of macrophages, 2) highlight the use by macrophages of the amoeboid and mesenchymal migration modes during their infiltration into an in vitro tumor model in 3D and 3) show that the matrix remodeling activity of macrophages during their migration plays a critical role in tumor cell invasion

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Garrot, Damien. « Etude par microscopie en champ proche des phénomènes de migration de matière photo-induite dans les matériaux photochromiques ». Paris 11, 2006. http://www.theses.fr/2006PA112046.

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L'objectif de ce travail est d'étudier les phénomènes de déformation photo-induite de matière dans les films minces polymères incorporant des molécules d'azobenzène. Cette étude s'appuie sur une expérience originale qui consiste à observer in-situ la cinétique de formation d'un réseau de surface sous illumination du film photochromique par une figure d'interférence. L'observation est basée sur l'utilisation de techniques couplées de microscopie à sonde locale qui permettent de corréler la morphologie photo-induite et la distribution du champ électromagnétique avec une résolution très inférieure au pas du réseau. Cette étude, menée en fonction de la polarisation de la lumière et de l'épaisseur des films, démontre qu'au moins quatre mécanismes microscopiques interviennent dans la déformation photo-induite des azo-polymères : la réorientation optique des photochromes, la réorganisation locale de la matrice, le transport dirigé de matière, le photo-blanchiment. La contribution de ces différents mécanismes est plus particulièrement révélée par l'existence de deux phénomènes observés pour la première fois. D'une part, la cinétique de déformation présente une transition entre deux régimes, l'un, au temps court, en phase avec l'excitation lumineuse et l'autre, au temps long, en opposition de phase. D'autre part, la morphologie des réseaux photo-induits dépend de façon spectaculaire de l'épaisseur des couches. L'ensemble des résultats obtenus apporte un nouvel éclairage sur certaines observations expérimentales antérieures, parfois contradictoires, notamment sur la différence entre les réponses d'un même matériau à une excitation optique en champ proche et champ lointain
The main goal of this PhD work is to study photo-induced matter deformation phenomena in thin polymeric film containing azobenzene moieties. This study is based on the in-situ observation of surface relief gratings kinetic of formation under illumination by an interference pattern. The observation relies on a coupled microscopy technique, allowing to correlate photo-induced morphology with the electromagnetic field distribution, with a resolution better than the lattice pitch. The study as a function of the light polarisation and of the film thickness shows that four microscopic mechanisms are involved in the photo-induced deformation of the azo-polymer: the optical reorientation of chromophore, the local reorganization of the matrix, oriented matter transport and the photobleaching. The contribution of these different mechanisms is evidenced by two phenomena observed for the first time. First, the kinetic of deformation presents a transition between two regimes, one, at short time, in phase with the light excitation, the other, at longer time, in opposition of phase. Second, the morphology of the induced relief grating depends strongly on the film thickness. This PhD work shed light on previous and somehow contradictory results, in particular in term of response of azo-polymer films at an excitation in near filed and far field optics

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Davies, Christopher W. « Quantification of Optical Parameters Using Frequency Domain Functional Near-Infrared Spectroscopy (FD-fNIRS) ». Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1559369168541587.

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Kalinin, Stanislav. « Electronic Energy Transfer within Asymmetric Pairs of Fluorophores : Partial Donor-Donor Energy Migration (PDDEM) ». Doctoral thesis, Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-338.

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Pequeño, Bueno Andrea. « Palabras, imágenes, cosas : sentidos de pertenencia y vínculos transnacionales en inmigrados/as chilenos/as en Barcelona, España, a partir de la cultura material visual ». Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/457428.

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Mi investigación doctoral explora los procesos identitarios y la experiencia familiar transnacional de inmigrantes chilenos/as que residen en unión mixta en Barcelona, España. Y lo hace poniendo especial atención a la cultura material, y con énfasis en la fotografía. Así, indago las trayectorias de desplazamiento y de conformación de pareja y vida en familia, los lazos con el país, la cultura y el núcleo de origen y, en suma, las relaciones y los ajustes continuos que suponen estos procesos y las identidades que entran en juego (género, país de procedencia, nivel socio-profesional, entre otras). Mi acento ha estado en entender el rol jugado por objetos e imágenes en estas vivencias. Y, paralelamente, comprender cómo influye en todo ello la pareja (su origen y características). La investigación tiene una naturaleza etnográfica cualitativa. En el trabajo de campo (realizado entre los años 2012 y 2015 en la Provincia de Barcelona, Comunidad Autónoma de Cataluña), contemplé la observación participante y las entrevistas en profundidad. En el marco de estas, incluí visitas guiadas por el espacio doméstico (Hometour) y el visionado conjunto de fotografías familiares. En algunos casos, además, los/as entrevistados/as construyeron -mediante objetos e/o imágenes- una narrativa sobre su proceso migratorio y de vida en pareja. Los/as informantes son chilenos/as que, habiendo nacido y permanecido en Chile hasta su mayoría de edad legal (18 años), se han establecido en Barcelona, en unión binacional heterosexual. Responden a distintos perfiles migratorios (económicos, estudios y amor) y a características sociodemográficas variadas. Incluí, además, a modo de contrapunto, a un informante en unión endogámica (Chile/Chile). Esto, bajo el interés de explorar la eventual influencia del origen de la pareja en los sentidos de pertenencia y los lazos transnacionales. Su trayectoria migratoria (exiliado político) ha aportado a la riqueza analítica de mi estudio. A ello también ha contribuido las particularidades biográficas y las características sociodemográficas variadas de los/as entrevistados/as (en género, edad, nivel socio-profesional, tiempo de residencia en Barcelona, entre otros aspectos). La forma de trabajo desplegada y el análisis mismo, han aportado antecedentes sobre los significados sociales y personales que tiene la cultura material y visual en la experiencia de los/as inmigrados/as y en sus lazos transnacionales, los modos en que se autorepresentan y las narrativas que se tejen, permitiendo con ello reconstruir trayectorias biográficas y de relacionalidad familiar, entre otros aspectos. Si bien, existe una amplia producción de investigaciones sobre migración y sobre cultura material, hasta hace poco eran escasos los trabajos que vincularan ambos ámbitos. En este sentido, mi tesis representa un aporte. Este se refuerza al considerar que la población chilena inmigrada en Cataluña y en España, ha merecido una exigua atención en los círculos académicos, más todavía en lo que respecta a parejas mixtas. Finalmente, señalar que mi formación doctoral se enmarca en el Programa Formación de Capital Humano Avanzado, de la Comisión de Nacional de Investigación Científica y Tecnológica (CONICYT) del Gobierno de Chile.
My doctoral research explores identity formation processes and transnational family experiences among Chilean immigrants living in mixed (binational) unions in Barcelona, Spain. In this effort, I pay attention to material culture, with a focus on photography. I analyze immigrants’ displacement trajectories and the conformation of family life and romantic partnerships, as well as ties with the country, culture and nucleus of origin. In sum, I look at the relationships and continuous adjustments that such processes entail and the different identities that come into play (gender, country of origin, socio-professional status, among others). I do this by focusing on the role of objects and images in such life experiences. In tandem, I analyze how these processes are affected by the migrant’s partner (place of origin and characteristics). This research project is ethnographic and qualitative in nature. My fieldwork (undertaken between 2012 and 2015 in the Province of Barcelona, Autonomous Community of Cataluña) is based on participant observation and in-depth interviews. During interviews, I included guided tours of domestic spaces (Hometour) and a shared visualization and discussion of family photos. In some cases, interviewees constructed- through objects and images- narratives about their migration process and couple life. My informants are people who were born in Chile, lived there until they reached the legal age of majority (18 years), and now reside in Barcelona in heterosexual binational unions. They exhibit diverse migratory profiles and motivations (economic, studies and love) as well as varied sociodemographic characteristics. I also included, as a counterpoint, an informant in an endogamic union (Chile/Chile). I included this informant to explore the relative influence of partner’s place of origin on the construction of a sense of belonging and transnational ties. His migratory trajectory (political exile) has contributed to the analytical richness of this study. The biographic particularities and varied sociodemographic characteristics of my interviewees (in terms of gender, age, socio-professional status, time residing in Barcelona, among others) further enrich this study. The methodology I deployed and the analysis of data itself contribute to the understanding of visual and material culture’s social and personal meanings in the experiences of immigrants and in their transnational ties. This research also delves on the ways immigrants represent themselves and the narratives they produce, allowing for a reconstruction of biographic trajectories and family relations, among other aspects. Even though there is a wealth of research on migration and material culture, up until recently few studies approached these two aspects together and the links between them. In this sense, my dissertation is a contribution. This contribution is accentuated by the fact that the Chilean population who has migrated to Cataluña and Spain, receives very scant attention among academic circles, even more so when it comes to considering binational couples. Finally, I would like to add that my doctoral studies were supported by Chile’s government program: Programa Formación de Capital Humano Avanzado, launched by the Comisión Nacional de Investigación Científica y Tecnológica (CONICYT).

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Opanasyuk, Oleg. « A new approach to the analyses of fluorescence depolarisation experiments in the presence of electronic energy transport ». Doctoral thesis, Umeå universitet, Kemiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-50050.

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A new and general procedure is described for a detailed analysis of time-resolved fluorescence depolarisation data in the presence of electronic energy migration. An isotropic ensemble of bifluorophoric molecules (D1-R-D2) has been studied to demonstrate its utility. Intramolecular donor-donor energy migration occurs between the two donor groups (D), which are covalently connected to a rigid linker group (R). These groups undergo restricted reorientational motions with respect to the R group. The analysis of depolarisation data basically involves the search for best-fit parameters which describe the local reorienting motions, the interfluorophore D1-D2 distance, as well as the mutual orientations of the donors. For this, the analysis is partly performed in the Fourier domain and the best-fit parameters are determined by using an approach based on a Genetic Algorithm. The energy migration process has been described by using Monte Carlo simulations and an extended Förster theory. It is found that this theory provides the least time-consuming computational method. Since one-photon and two-photon excited fluorescence experiments can be applied for energy migration studies, a general and unified theoretical formulation is given. To exemplify the developed quantitative approach the depolarisation of the fluorescence in the presence of electronic energy migration within a bis-(9-anthrylmethylphosphonate) bisteroid molecule has been studied by time-resolved two-photon excited fluorescence depolarisation experiments. To solely obtain information about local reorientations of the 9-anthrylmethyl group, also the mono-(9-anthrylmethylphosphonate) bisteroid was studied, which enabled modelling of the ordering potential of the donor. Values of the two-photon absorption tensor components were obtained. To describe the discrepancy between the measured values of the initial anisotropy and fundamental anisotropy predicted by theory the distribution of absorption tensor caused by fast processes have been introduced. An angular parameter of absorption tensor was determined. Reasonable values of the distance between the 9-anthrylmethyl groups, as well as for their mutual orientation were obtained.

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Norlin, Nils. « Extended Förster Theory of Electronic Energy Transport within Pairs of Reorienting Chromophoric Molecules ». Doctoral thesis, Umeå universitet, Kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-22471.

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An extended Förster theory (EFT), previously derived (L. B.-Å. Johansson et al. J. Chem. Phys., 1996,105) has theoretically been adapted and used in simulations of donor-acceptor energy transfer (DAET), which is a process often referred to as FRET. It was shown that the classical Förster theory is only valid in the initial part of the fluorescence decay. In this thesis an EFT is derived and outlined for electronic energy transport between two fluorescent molecules which are chemically identical, but photophysically non-identical. The energy migration within such asymmetric pairs is partially reversible and therefore referred to as partial donor-donor energy migration (PDDEM). The previously derived model of PDDEM (S. V. Kalinin et al. Spectrochim Acta Part A, 2002,58) is an approximation of the EFT. In particular, the EFT accounts for the time-dependent reorientations as well as the distance that influence the rate of electronic energy migration. The reorientation of the fluorophores transition dipole moments has been simulated using Brownian dynamics. As a result, the related “k2-problem” has been solved. The EFT of PDDEM has also been studied regarding the effect of PDDEM on experimental observables e.g. quantum yield of fluorescence and steady-state anisotropies

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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.

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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.

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ROCHA, Bruno César Luz Macena. « Estudo da sazonalidade, distribuição, abundância e comportamento migratório do tubarão-baleia (Rhincodon typus Smith, 1828) no Arquipélago de São Pedro e São Paulo ». Universidade Federal Rural de Pernambuco, 2010. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6245.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
In Saint Peter and Saint Paul archipelago (SPSPA), located at mid-Atlantic ridge, near to Equator line, population aspects of whale sharks was analized through in situ observation on distribution, seasonality, different behavior, and photo-identification. The movements of whale sharks was tracked using two models of satellite tag: SAT (Satellite Argos-linked transmitter) and PSAT (Pop up satellite archival transmitting tag) in one male (TB-01; 4.8 m) and one female (TB-02; 8.5 m),respectively. Whale shark occur in SPSP adjacencies yearround,although, are more abundant in the first semester, mainly, in February, March, and June. The annual record mean was 10.8 year-1 between 2000 and 2009. The size ranges from 1.8 to 14.0 m with mean± s.d. equal to 7.4± 2.4 m and the majority (62.9%) of whale sharks smaller than 9.0 m, under the estimated size at first maturation. Data received from Argos Satellite system indicate that the whale shark swam away from archipelago heading west. Both sharks spent the major of the time at surface, and the TB-02 dove into bathypelagic zone, attaining the maximum depth of 1,976 m. This was the first initiative to understand behavioral and population dynamics aspects of the whale sharks as well as the movement in Brazil and Equatorial Atlantic from SPSPA and will continue in the hope of building better conservation strategies.
No Arquipélago de São Pedro e São Paulo (ASPSP), localizado na dorsal meso-Atlântica, próximo à linha do Equador, foram analisados aspectos da população do tubarão baleia por meio de observação in situ. Informações sobre a distribuição e sazonalidade de ocorrência, diferentes comportamentos foram coletados e, quando possível, os espécimes foram fotografados para posterior individualização. Para elucidação do deslocamento do tubarão-baleia, a partir do ASPSP, foram utilizados dois modelos de transmissores via satélite, o SAT (Satellite Argos-linked tag) e o PSAT (Pop up satellite archival transmitting tag) em um macho (TB-01) e uma fêmea (TB-02) de 4,8 e 8,5 m, respectivamente. Os tubarões-baleia visitam o arquipélago durante o ano inteiro, entretanto, o primeiro semestre possui uma frequência mais elevada, principalmente nos meses de fevereiro, março e junho. A média anual de registros foi 10,8 ano-1 entre 2000 e 2009. Os comprimentos variaram entre 1,8 e 14,0 m com média± d.p. igual a 7,4± 2,4 m, com a maior parte (62,9%) dos tubarõesbaleia com comprimento abaixo do tamanho estimado para primeira maturação. Os dados dos transmissores recebidos pelo Sistema Argos de satélites indicaram que os tubarões se afastaram do ASPSP, logo após a marcação, em direção oeste. Ambos os tubarões permaneceram a maior parte do tempo na superfície e o TB-02 realizou mergulhos batipelágicos alcançando a profundidade máxima de 1.976 m. Esta foi a primeira iniciativa para se compreender aspectos populacionais e comportamentais, bem como da movimentação de tubarões-baleia no Brasil e no Atlântico Equatorial a partir do ASPSP e terá continuidade na expectativa de construir de estratégias espaciais de conservação.

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Yang, Lei. « Hole Transport Materials for Solid-State Mesoscopic Solar Cells ». Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-232271.

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The solid-state mesoscopic solar cells (sMSCs) have been developed as a promising alternative technology to the conventional photovoltaics. However, the device performance suffers from the low hole-mobilities and the incomplete pore filling of the hole transport materials (HTMs) into the mesoporous electrodes. A variety of HTMs and different preparation methods have been studied to overcome these limitations. There are two types of sMSCs included in this doctoral thesis, namely solid-state dye-sensitized solar cells (sDSCs) and organometallic halide perovskite based solar cells. Two different types of HTMs, namely the small molecule organic HTM spiro-OMeTAD and the conjugated polymer HTM P3HT, were compared in sDSCs. The photo-induced absorption spectroscopy (PIA) spectra and spectroelectrochemical data suggested that the dye-dye hole conduction occurs in the absence of HTM and appears to be of significant importance to the contribution of hole transport. The PIA measurements and transient absorption spectroscopy (TAS) indicated that the oxidized dye was efficiently regenerated by a small molecule organic HTM TPAA due to its excellent pore filling. The conducting polymer P3HT was employed as a co-HTM to transfer the holes away from TPAA to prohibit the charge carrier recombination and to improve the hole transport. An alternative small molecule organic HTM, MeO-TPD, was found to outperform spiro-OMeTAD in sDSCs due to its more efficient pore filling and higher hole-mobility. Moreover, an initial light soaking treatment was observed to significantly improve the device performance due to a mechanism of Li+ ion migration towards the TiO2 surface. In order to overcome the infiltration difficulty of conducting polymer HTMs, a state-of-the-art method to perform in-situ photoelectrochemical polymerization (PEP) in an aqueous micellar solution of bis-EDOT monomer was developed as an environmental-friendly alternative pathway with scale-up potential for constructing efficient sDSCs with polymer HTMs. Three different types of HTMs, namely DEH, spiro-OMeTAD and P3HT, were used to investigate the influence of HTMs on the charge recombination in CH3NH3PbI3 perovskite based sMSCs. The photovoltage decay measurements indicate that the electron lifetime (τn) of these devices decreases by one order of magnitude in the sequence τspiro-OMeTAD > τP3HT > τDEH.

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Bernert, Constantin. « Untersuchung photorefraktiver Materialien mittels optischer Ptychographie ». Master's thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-216063.

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In der vorliegenden Arbeit wird die neuartige Mikroskopiemethode der Ptychographie für die Untersuchung photorefraktiver Materialien genutzt. Photorefraktive Materialien zeichnen sich durch die Generation lichtinduzierter Brechungsindexänderungen aus. Die Ptychographie bietet die Möglichkeit, neben der generierten Brechungsindexänderung im photorefraktiven Material auch die für die Generation genutzte Intensitätsverteilung des Laserstrahls zu bestimmen. Es wird sowohl die Abhängigkeit der Brechungsindexänderung von der Zeit der Generation als auch die Abhängigkeit von der Polarisation des Lasers gemessen. Durch den Vergleich der gewonnenen Werte mit einer numerischen Simulation des photorefraktiven Effekts werden mikroskopische Parameter der lichtinduzierten Ladungswanderung ermittelt. Zudem wird aus der polarisationsabhängigen ptychographischen Messung das Raumladungsfeld und die korrespondierende Ladungsdichte im Material berechnet. Die Ptychographie liefert damit einen neuen Zugang zum quantitativen Verständnis der Photorefraktivität
In the present thesis the novel microscopy technique of ptychography is applied to the investigation of photorefractive materials. Photorefractive materials exhibit a change of the refractive index due to the exposure to light. The method of ptychography determines the refractive index change of the material together with the intensity distribution of the laser beam that was used for its generation. In one part of the experiment the time dependence of the refractive index change versus the generation time is investigated, in the other part of the experiment the dependence of the refractive index change to the polarisation of the laser beam is examined. Microscopic parameters of the photorefractive charge migration are determined with the utilisation of a numerical simulation of the photorefractive effect and its comparison with the measurement. Finally, the whole space charge field with the corresponding space charge density is calculated from a set of ptychographic measurements of one refractive index change with different polarisation directions of the laser. The presented experiments and their evaluation show, that the method of ptychography opens a new possibility for a quantitative understanding of the photorefractive effect

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SAVO, ROMOLO. « Transport in Complex Heterogeneous Photonic Structures ». Doctoral thesis, 2013. http://hdl.handle.net/2158/797466.

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Proper understanding of multiple scattering of light is essential in many areas of science and technology. The interest ranges from fundamental photonics and the quest for the elusive phenomena of Anderson localization, to atmospherical optics and climate research, to applied spectroscopy. In biomedical optics, proper account of light scattering is necessary to extract information on crucial parameters such as blood oxygenation and hemoglobin concentration. In industry, non-destructive testing of e.g. food products or pharmaceuticals involve spectroscopic measurements on materials in which light is multiply scattered. This broad interest is reflected by an enormous body of science regarding light transport in turbid media. Typically, light transport is in these areas is viewed as a random walk based on independent and exponential distributed steps, and that the diffusion constant is given by the famous relation D=1/3vE lt (where vE is the energy velocity and lt the average length of the exponential steps). This picture is appropriate for systems where scatterers are uniformly, but randomly, distributed in space. However, there are many systems in which scatterers are not uniformly distributed. An obvious example is our atmosphere, having complex cloud layers that determines our earth's solar energy balance. In recent years, such aspects of light transport are receiving increasing attention, and an area that could be referred to as anomalous transport of light has been formed. Along with the current interest in super-diffusion coming from the atmospherical optics community, the recent introduction of well-controlled heterogeneous laboratory systems with superdiffusive properties (so called Lévy glass ) has further increased the interest in this topic. However, how heterogeneous distributions of scatterers influence light transport remains poorly understood. The main aim of this thesis is to fill this gap, both experimentally and theoretically.

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Lin, Huang-Yi, et 林皇屹. « High frequency photon migration spectroscopy by mode locked laser ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75683869600540789694.

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碩士
國立交通大學
照明與能源光電研究所
102
In this paper, we use the higher-order-harmonic modulations of mode-locked laser pulses to offer multiple modulation frequencies for Frequency Domain Photon Migration (FDPM) System. Combined with a demodulation circuit, we demonstrate a GHz FDPM system, which breaks the bandwidth limitation of modulated source. In addition,for future clinical applications, we build a portable mode- locked Yb-fiber laser.

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30

Hoffmann, Joe. « Three-Dimensional Biomimetic Patterning to Guide Cellular Migration and Organization ». Thesis, 2012. http://hdl.handle.net/1911/71659.

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This thesis develops a novel photopatterning strategy for biomimetic scaffolds that enables spatial and biochemical control of engineered cellular architectures, such as the microvasculature. Intricate tools that allow for the three dimensional (3D) manipulation of biomaterial microenvironments will be critical for organizing cellular behavior, directing tissue formation, and ultimately, developing functional therapeutics to treat patients with critical organ failure. Poly(ethylene glycol) (PEG) based hydrogels, which without modification naturally resist protein adsorption and cellular adhesion, were utilized in combination with a two-photon laser patterning approach to covalently immobilize specific biomolecules in custom-designed, three-dimensional (3D) micropatterns. This technique, known as two-photon laser scanning lithography (TP-LSL), was shown in this thesis to possess the capability to micropattern multiple different biomolecules at modular concentrations into a single hydrogel microenvironment over a broad range of size scales with high 3D resolution. 3D cellular adhesion and migration were then explored in detail using time-lapse confocal microscopy to follow cells as they migrated along micropatterned tracks of various 3D size and composition. Further, in a valuable modification of TP-LSL, images from the endogenous microenvironment were converted into instructions to precisely direct the laser patterning of biomolecules within PEG-based hydrogels. 3D images of endogenous microvasculature from various tissues were directly converted into 3D biomolecule patterns within the hydrogel scaffold with precise pattern fidelity. While tissue engineers have previously demonstrated the formation of vessels through the encapsulation of endothelial cells and pericyte precursor cells within PEG-based hydrogels, the vessel structure had been random, uncoordinated, and therefore, ultimately non-functional. This thesis has utilized image guided TP-LSL to pattern biomolecules into a 3D structure that directs the organization of vessels to mimic that of the endogenous tissue vasculature. TP-LSL now stands as a valuable tool to control the microstructure of engineered cellular architectures, thereby providing a critical step in the development of cellularized scaffolds into functional tissues. Ultimately, this thesis develops new technologies that advance the field of regenerative medicine towards the goal of engineering viable organs to therapeutically treat the 18 patients who die every day waiting on the organ transplant list.

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Po-AnChen et 陳柏安. « Investigation and Design of Miniature Receivers for Non-Invasive Frequency Domain Photon Migration Examination Systems ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/yrbjh6.

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碩士
國立成功大學
電機工程學系
102
Two miniature FDPM receivers is achieved in this thesis to replace the partial function of the NA-based system. Due to the compact receiver, it can be cost-down and be portable. The first one is a separate signal sources structure with extra phase error elimination. Also, Noise analysis is applied to estimate the system performance. The second receiver is a joint signal source structure to reduce the number of high frequency signal sources. Phase cancellation problem caused by joint signal source is solved by adding image rejection mixer. Severe amplitude variation caused by signal non-synchronous can also be solved by the joint signal source structure. The average amplitude and phase error of the separate structure are less than 8 % and 0.2°, respectively. The error of absorb and scatter coefficient are about 10 % and 3 %, respectively. Also, the average amplitude and phase error of the joint structure are less than 2.5% and 0.35°. The error of absorb and scattering coefficient are about 4.67 % and 3.38 %, respectively. These results show that the miniature receivers can achieve low error compared to the NA-based system with thousand times cheaper and much smaller size.

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Ming-CingWang et 王銘慶. « Variation of Glucose Concentration in Tissue Phantom Monitored with a Frequency Domain Photon Migration System ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/90739157622952838873.

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碩士
國立成功大學
光電科學與工程學系
101
In this thesis, we demonstrate the use of optical method, frequency domain photon migration system (FDPM), to determine physiological parameters of biological tissues. It use a 808 nm laser diode as the light source coupled with mathematical photon transport models to accurately determine optical absorption (µa) and reduced scattering (µs′) properties of phantoms. Here, we employed the fiber probe with the FDPM technique to quantify the optical properties of in-vitro phantom. First, we use FDPM system to measure five glucose concentration liquid phantoms of various absorption and scattering properties. Second, we speculate that resolve the slight variation of optical properties is the advantage of the broad bandwidth FDPM system by using the diffusion model. Third, we implement the scaling Monte Carlo method by using Matlab. The scaling method can reduce computation time by nearly 5 orders of magnitude, and the error is less than 3% which is compared with the original Monte Carlo algorithm. The scaling Monte Carlo algorithm can be used obtain spatially resolved reflectance spectra of tissue with different optical parameters without significantly affecting simulation time. Finally, we speculate that resolve the slight variation of optical properties in scaling Monte Carlo method is 100 mg/dl. In addition, we combine the simulated result at 808 and 1550 nm with the specific advantage. Our study reveals that the FDPM system provides a fast and noninvasive way for tissue composition quantification.

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Shang-PinYeh et 葉上賓. « Measuring the Optical Properties of Superficial Turbid Sample Using the Steady State Frequency Domain Photon Migration System ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/68135953063422377774.

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碩士
國立成功大學
光電科學與工程學系
100
In this thesis, we demonstrate the use of optical method, steady state frequency domain photon migration system (SSFDPM), to determine physiological parameters of biological tissues. It uses near-infrared light (from 600 to 1100 nm) coupled with mathematical photon transport models to accurately determine optical absorption (µa) and reduced scattering (µs′) properties of tissues. Absorption coefficient (µa) and reduced scattering coefficient (µs′) can be used to determine the chromophore concentrations, such as oxygenated hemoglobin, deoxygenated hemoglobin, water, and lipid, of biological tissues. Here, we employed the diffusing probe with the SSFDPM technique to quantify the optical properties of in-vivo skin. First, we characterize the stability of the amplitude and phase of the frequency domain photon migration system (FDPM) so that we can understand the limitations of our system. Second, we prepare four samples of different absorption to study the system linearity. Third, we use FDPM system to measure six liquid phantoms of various absorption and scattering properties. Finally, we combine the steady state (SS) and FDPM which is called SSFDPM to measure the liquid phantom, and quantify the chromophore concentrations of liquid phantoms. In addition, we carry out SSFDPM measurements on the in-vivo dorsal forearm and show the quantitative physiological concentration and compare with SS measurements. Our study reveals that the SSFDPM system provides a fast and noninvasive way for tissue composition quantification.

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Ming-WeiLee et 李銘偉. « Using a frequency domain photon migration system in the reflectance mode for rapidly quantifying the tissue oxygen saturation and arterial oxygen saturation ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/8dh69m.

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碩士
國立成功大學
光電科學與工程學系
103
A frequency domain photon migration system in the reflectance mode for rapidly quantifying the tissue oxygen saturation and arterial oxygen saturation are presented in this study. The proposed system improves the shortcomings and limitations of the commercial pulse oximeters, including the reflectance mode overcomes the position limits of the transmissive mode, while the advantages of measuremental method can simultaneously measure the tissue oxygen saturation and arterial oxygen saturation and widely measuring range of arterial oxygen saturation. The results presented in the frequency domain photon migration system, we rapidly measured the accuracy of optical properties and mean absolute percentage error in three wavelengths which from 1.3% to about 11%, indicating the accuracy of optical properties within a reasonable range. In vivo experiments we measured six healthy adults totally, four men and two women, the measured positions include two parts: fingers and palm, measured environment is under static stability and under pressure with 60mmHg reached vein atresia. We analyzed the absorption coefficient, reduced scattering coefficient for each wavelength, oxy-hemoglobin concentration, deoxy-hemoglobin concentration, tissue oxygen saturation, pulsating with change amount of oxy-hemoglobin concentration and deoxy-hemoglobin concentration, arterial oxygen saturation, and optical properties of frequency domain response analysis information for each wavelength. The system can provide a wealth of physiological information, but relatively stability of the system is very important. In vivo experiments in Section 4.3, stability of the system can become better. We will improve the stability of the system for the first goal in future work.

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Po-JungHuang et 黃柏蓉. « Determination of the skin optical properties from frequency domain photon migration measurements carried out at source to detector separations shorter than 3 mm ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/fef4b5.

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碩士
國立成功大學
光電科學與工程學系
103
In this study, we propose a method to measure human skin with SDS = 1mm by FDPM system. In order to improve the shortcomings of traditional photon propagation model, we established a new photon propagation model which combined the GPU-MCML and ANN method to derive the sample absorption coefficient、reduced scattering coefficient corresponding to the amplitude and phase delay with the frequency. The new model can substitute traditional Monte Carlo model and standard diffusion equation which have some using limitation. In simulation, Monte Carlo is considered as a gold standard model of photon propagation. However it consumes lots of time to do the simulation. Compared with Monte Carlo, the percent deviation of amplitude and phase which simulated by artificial neural networks are about 4% and 6%, respectively. In the other hand, comparing with Monte Carlo, the percent deviation of amplitude and phase which simulated by standard diffusion equation are about 30% and 17%, respectively. Therefore compared with diffusion equation the new model with a 1mm source to detector separation indeed has its absolute advantage. We also use the homogeneous phantom which optical properties is known to confirm the feasibility of the artificial neural networks model. In experience,we measured three position of three healthy adults, including the finger, the inner forearm and outer forearm with the artificial neural networks model extrapolated absorption coefficient、reduced scattering coefficient with three wavelengths. And then we put the absorption coefficient into the chromophore fitting to quantify the chromophore concentrations of tissue and StO2. In conclusion, our new artificial neural networks model has better efficiency and wider applied range than other traditional model, which can accurately calculate the optical properties of the superficial skin tissue.

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RAHARIMANITRA, Fabia Nirina. « Contribution à l'étude des architectures basées sur le multiplexage en temps et en longueur d'onde dans le réseau d'accès, permettant la migration vers la nouvelle génération de PON (NG-PON) à 10 Gbits/s ». Phd thesis, 2012. http://tel.archives-ouvertes.fr/tel-00740848.

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Ces travaux de recherches visent à étudier et à proposer de nouvelles architectures dans le contexte d'une Nouvelle Génération de Réseau d'Accès Optique Passif (NG-PON). Cette nouvelle génération d'équipements se justifie par l'augmentation des besoins en débit (descendant et/ou montant), ou d'éventuelles futures obligations réglementaires. Elle a pour fil conducteur le souci d'optimiser les coûts de déploiement de l'accès FTTH. Depuis 2010, l'organisme de pré-normalisation, le FSAN (associé à l'ITU) a prévu une action sur le thème du NG-PON qui se décline en XG-PON1 pour la première vague (débit 10 Gbit/s descendant et 2.5 Gbit/s montant) puis en un deuxième volet appelé NG-PON2 (pour une offre viable commerciale basée sur un débit de l'ordre de 1 Gbit/s) pour succéder au G-PON et au XGPONl. Des évaluations ont été menées sur la transmission optique, plus exactement au niveau de la couche physique (mesures de taux d'erreur, budget optique, portée) pour en déduire par la suite la faisabilité et la performance des systèmes. Deux thématiques ont structuré le travail de thèse sur la base de ce périmètre d'analyse : i) la recherche de solutions techniques pour optimiser le nombre de centraux " opticalisés ", ii) la recherche de solutions dans le modem client pour permettre de se connecter à des solutions de type une longueur d'onde par client. Un combineur optique sans pertes répondant au meilleur remplissage des cartes OLTs (Optical Line Termination) au Central Optique a été démontré. Ce combineur optique permet la réduction des sites NRO (Noeud de Raccordement Optique). Cette thèse s'intéresse aussi à l'ONU (Optical Network Unit), l'équipement du côté du client qui est un élément fondamental qui impacte le modèle de coût dans les réseaux d'accès. Les ONU achromatiques (dont les émetteurs sont identiques quelque soit la longueur d'onde d'émission) étudiés sont soit à base de source large à découpage spectral (" Spectrum Slicing ") soit à base de lasers accordables. Ils offrent l'avantage de la simplicité dans une architecture dont le multiplexage et l'accès multiples sont basés sur la longueur d'onde. Le format de modulation avancé de type OFDM et l'emploi de la technique de traitement de signal comme l'égaliseur sont également mis en relief dans ces travaux de thèse. Ces deux aspects correspondent à des mises en oeuvre d'outils de l'état de l'art le plus récent pour compenser les pénalités d'une transmission optoélectronique.

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Gibb, Giselle Renee. « Humpback whales (Megaptera novaeangliae) in the South Pacific breeding grounds : an allocation from feeding areas and an abundance estimate of whales specific to French Polynesia waters ». Thesis, 2009. http://hdl.handle.net/1957/11995.

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South Pacific humpback whales were devastated by commercial whaling in their Antarctic feeding areas during the 20th century. Understanding migratory connections and current abundance of these isolated breeding stocks is crucial for the allocation of historical Antarctic catches in population dynamic models used to assess current recovery. However, only a small number of migratory connections have been documented between Oceania breeding stocks within the South Pacific and feeding areas in the Antarctic. In addition, little is known about abundance of these stocks which encompass a vast oceanic region. For this thesis I first used mixed-stock analysis (MSA) to allocate migratory connections from four Antarctic feeding areas (n=142) to seven South Pacific breeding stocks (n=1,373), including four in Oceania, based on genetic marker frequencies. The use of this method was justified by the breeding stocks showing genetic differentiation at the haplotype level with an F[subscript ST] value of 0.027 (p-value <0.001). The results showed a relatively strong connection of Western Australia to Antarctic Area IV, Tonga to the border of Antarctic Area VI/I, Colombia to the Antarctic Peninsula, and a split allocation of Eastern Australia and New Caledonia to Antarctic Area V. This study provides the first population-level information supporting previous individual-based studies that humpback whale migration may not necessarily be direct north south. Next, utilizing capture-recapture methodology of unique humpback whale fluke photographs, I estimated abundance of one of the least studied Oceania breeding stocks, French Polynesia, a stock which also showed no significant migratory allocation using MSA. Taking into consideration the possible advantages of using Quality Control (QC) photographs to minimize bias in matching, estimates were generated using the complete photo catalogue and also using only photographs adhering to QC criteria. I found that the choice of using QC has an effect on the abundance generated and discuss the implications of this finding. Despite the photo catalogue used, the French Polynesia stock is estimated to number less than 1,900 individuals. Lastly, to provide additional information on the French Polynesia stock I used photo-identification to compare French Polynesia whales to whales in the Antarctic Peninsula and Strait of Magellan (Antarctic Area I), a possible migratory connection suggested by previous microsatellite genotyping. No conclusive matches were found. Although this does not discount the possibility of a few migrants traveling between these regions it does indicate the Antarctic Peninsula and the Strait of Magellan are not primary feeding areas of French Polynesia. This new information regarding abundance and migration of French Polynesia whales is important for the Comprehensive Assessment of Southern Hemisphere humpback whales. This document is currently being completed as the International Whaling Commission considers the next critical steps in recovery for Oceania humpback whales stocks.
Graduation date: 2010

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Henriques, Renato F. « Monitorização da zona costeira tendo em vista a sua vulnerabilidade – aplicação à zona costeira noroeste de Portugal ». Doctoral thesis, 2007. http://hdl.handle.net/1822/42711.

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Tese de doutoramento em Geologia
A elevada dinâmica que caracteriza a zona costeira portuguesa tem implicações directas para as comunidades humanas aí instaladas. Nos últimos anos agudizou-se, nalguns locais, a migração para o interior do sistema praia/duna, pondo em perigo algumas localidades e levando ao aumento da construção de obras de defesa costeira, por vezes feitas com carácter de emergência. O aumento do conhecimento sobre o comportamento dinâmico das zonas costeiras é um contributo fundamental para a elaboração de planos de gestão integrada destas zonas. A monitorização contínua é a melhor forma de obter dados que permitam conhecer a sua tendência evolutiva, possibilitando a previsão de cenários futuros. Este trabalho deve ser estendido a toda a costa portuguesa, ser baseado em meios técnicos diversificados e realizado com a maior frequência possível. Se a monitorização for realizada com técnicas demasiado caras, a eficácia desejada deste importante trabalho pode ser comprometida. A presente dissertação centrou-se no desenvolvimento de técnicas de monitorização de baixo custo, baseadas em fotografia aérea. Foram desenvolvidos protótipos de obtenção de fotografia aérea utilizando poucos recursos económicos, mas com qualidade suficiente para ser utilizada na monitorização das mudanças nas zonas costeiras. Foram escolhidos três segmentos da costa noroeste de Portugal, situados entre a Praia de Cortegaça e a Praia de Mira, para os quais foi feita a comparação entre a fotografia obtida com os protótipos desenvolvidos e a fotografia histórica existente. A partir deste trabalho, foi possível calcular taxas médias de migração, ao longo de diversos períodos temporais, a partir da medição da mobilidade de indicadores de migração costeira. Foi, também, possível, conjugando a fotografia aérea com técnicas de SIG, estudar a ocorrência de galgamentos marinhos na região entre o Furadouro e a praia do Torrão do Lameiro. Tendo em conta que o conhecimento da dinâmica costeira não pode ser dissociado do conhecimento dos sedimentos em movimento, foi realizada uma colheita de sedimentos na praia e na plataforma continental adjacente, na região do Furadouro. Embora tenham sido colhidas poucas amostras, foi já possível detectar alguns padrões na distribuição de sedimentos; foram identificadas diferenças entre a dimensão dos sedimentos colhidos a mais de 1000 metros da costa e a dos colhidos na praia e na pré-praia.
The high dynamical behaviour that characterizes the Portuguese coastal zone has direct implications for the human communities installed there. During the last years, inland migration of the dune/beach system has increased, putting some localities in danger and leading to the increased building of hard engineering coastal defences, sometimes with emergency character. The increased knowledge about the dynamic behaviour of the coastal zones is an important contribution to integrated coastal zone management (ICZM). Continuous monitoring is the best form of gathering important information that allows a better knowledge of the past evolution trend, making the forecast of future scenarios possible. This work should be extended to the total extend of the Portuguese coast, based on diversified techniques and carried out at the highest frequency. If based on expensive techniques, the desired effectiveness of this important work can be compromised. The present work was focused on the development of low-cost monitoring techniques, based on aerial photography. Prototypes for air photograph achievement has been developed, using low-cost resources, but with enough quality to be used for the surveying of coastal zone changes. Three segments of the Northwest coastal zone of Portugal, located between Cortegaça Beach and Mira Beach, were chosen. The comparison between photographs got with the developed prototypes and the existing historical photographs was done in those segments. With this work, it was possible to calculate average migration rates over different time periods, from the measurement of the mobility of coastal migration indicators. Through the combination of aerial photography with GIS techniques, it was also possible to study the occurrence of marine overwashes in the area between Furadouro and the beach of Torrão do Lameiro. Taking into account that the knowledge of coastal dynamics cannot be dissociated from the knowledge of the sediments in movement, a sampling of sediments from the beach and the adjacent continental shelf was carried out in the area of Furadouro. Although few samples were collected, some patterns in the distribution of sediments were recognized and size differences identified between sediments sampled at about 1000 meters from the coast and those sampled on the beach and in the nearshore.
Fundação para a Ciência e Tecnologia (FCT)

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PATTELLI, LORENZO. « Imaging light transport at the femtosecond scale : a walk on the wild side of diffusion ». Doctoral thesis, 2017. http://hdl.handle.net/2158/1087854.

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In this thesis work we investigated light transport in scattering media from a spatio-temporal perspective. To this purpose, we have designed and developed an experimental optical-gating setup and a new Monte Carlo software library focused on the measurement and simulation of spatio-temporal evolution of light transport down to a sub-picosecond resolution. The unique properties of both these tools allowed us to unveil an array of unexplored aspects of light propagation occurring in the extremely general plane-parallel slab geometry, which are of relevance both for application and fundamental purposes due to their asymptotic nature. Indeed, time-domain techniques are commonly considered to offer the most straightforward and powerful characterization capabilities, in that they allow to selectively address different transport regimes and directly observe their evolution. However, as we extensively demonstrate, combining the temporal information with wide-field spatial imaging capabilities offers a significant improvement, unveiling a set of irreducible information that could not be accessed from separate spatial and temporal characterizations.

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Pattelli, Lorenzo. « Imaging light transport at the femtosecond scale ». Doctoral thesis, 2018. http://hdl.handle.net/2158/1157248.

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In this thesis work we investigated light transport in scattering media from a spatio-temporal perspective. To this purpose, we have designed and developed an experimental optical-gating setup and a new Monte Carlo software library focused on the measurement and simulation of spatio-temporal evolution of light transport down to a sub-picosecond resolution. The unique properties of both these tools allowed us to unveil an array of unexplored aspects of light propagation occurring in the extremely general plane-parallel slab geometry, which are of relevance both for application and fundamental purposes due to their asymptotic nature. Indeed, time-domain techniques are commonly considered to offer the most straightforward and powerful characterization capabilities, in that they allow to selectively address different transport regimes and directly observe their evolution. However, as we extensively demonstrate, combining the temporal information with wide-field spatial imaging capabilities offers a significant improvement, unveiling a set of irreducible information that could not be accessed from separate spatial and temporal characterizations.

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Bernert, Constantin. « Untersuchung photorefraktiver Materialien mittels optischer Ptychographie ». Master's thesis, 2016. https://tud.qucosa.de/id/qucosa%3A30065.

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Résumé :

In der vorliegenden Arbeit wird die neuartige Mikroskopiemethode der Ptychographie für die Untersuchung photorefraktiver Materialien genutzt. Photorefraktive Materialien zeichnen sich durch die Generation lichtinduzierter Brechungsindexänderungen aus. Die Ptychographie bietet die Möglichkeit, neben der generierten Brechungsindexänderung im photorefraktiven Material auch die für die Generation genutzte Intensitätsverteilung des Laserstrahls zu bestimmen. Es wird sowohl die Abhängigkeit der Brechungsindexänderung von der Zeit der Generation als auch die Abhängigkeit von der Polarisation des Lasers gemessen. Durch den Vergleich der gewonnenen Werte mit einer numerischen Simulation des photorefraktiven Effekts werden mikroskopische Parameter der lichtinduzierten Ladungswanderung ermittelt. Zudem wird aus der polarisationsabhängigen ptychographischen Messung das Raumladungsfeld und die korrespondierende Ladungsdichte im Material berechnet. Die Ptychographie liefert damit einen neuen Zugang zum quantitativen Verständnis der Photorefraktivität.:1 Einleitung 2 Theoretische Vorbetrachtungen 2.1 Ptychographie 2.1.1 Messung 2.1.2 Modell und Rekonstruktion 2.1.3 Ortsauflösung 2.2 Photorefraktiver Efekt 2.2.1 Lithiumniobat - Musterbeispiel für die Photorefraktivität 2.2.2 Ein-Zentrum-Modell 2.2.3 Brechungsindexänderung 2.2.4 Hohe Intensitäten 2.3 Raumladungsfeld 2.3.1 Ableitung des Feldes aus den Messgrößen 2.3.2 Raumladungsverteilung 2.3.3 Oberflächendeformation 2.3.4 Dynamik der Ladungen und des Feldes 3 Messungen 3.1 Proben 3.1.1 Ptychographische Teststruktur 3.1.2 LiNbO3:Fe 3.2 Versuchsanordnung 3.2.1 Experimenteller Aufbau 3.2.2 Grenze der Ortsauflösung 3.2.3 Charakterisierung des Laserstrahls 3.2.4 Experimentelle Überprüfung der Näherungen 3.3 Dynamik der Brechungsindexänderung 3.4 Polarisationsabhängigkeit der Brechungsindexänderung 4 Auswertung 4.1 Dynamik des Raumladungsfeldes und der Ladungen 4.1.1 Simulation 4.1.2 Vergleich zwischen Messung und Simulation 4.1.3 Dynamik der Ladungsverteilung 4.1.4 Fazit 4.2 Berechnung des Raumladungsfeldes 4.2.1 Raumladungsfeld und Ladungsverteilung 4.2.2 Simulation 4.2.3 Asymmetrie der Ladungsverteilung 4.2.4 Fazit 5 Zusammenfassung Appendizes A Physikalische Konstanten B Tensoren für LiNbO3 C Ungenäherte Herleitung der Brechungsindexänderung D Implementierung eines iterativen Verfahrens zur Bestimmung der Dynamik des Ein-Zentrum-Modells E Quelltext der Implementierung des iterativen Verfahrens Literaturverzeichnis
In the present thesis the novel microscopy technique of ptychography is applied to the investigation of photorefractive materials. Photorefractive materials exhibit a change of the refractive index due to the exposure to light. The method of ptychography determines the refractive index change of the material together with the intensity distribution of the laser beam that was used for its generation. In one part of the experiment the time dependence of the refractive index change versus the generation time is investigated, in the other part of the experiment the dependence of the refractive index change to the polarisation of the laser beam is examined. Microscopic parameters of the photorefractive charge migration are determined with the utilisation of a numerical simulation of the photorefractive effect and its comparison with the measurement. Finally, the whole space charge field with the corresponding space charge density is calculated from a set of ptychographic measurements of one refractive index change with different polarisation directions of the laser. The presented experiments and their evaluation show, that the method of ptychography opens a new possibility for a quantitative understanding of the photorefractive effect.:1 Einleitung 2 Theoretische Vorbetrachtungen 2.1 Ptychographie 2.1.1 Messung 2.1.2 Modell und Rekonstruktion 2.1.3 Ortsauflösung 2.2 Photorefraktiver Efekt 2.2.1 Lithiumniobat - Musterbeispiel für die Photorefraktivität 2.2.2 Ein-Zentrum-Modell 2.2.3 Brechungsindexänderung 2.2.4 Hohe Intensitäten 2.3 Raumladungsfeld 2.3.1 Ableitung des Feldes aus den Messgrößen 2.3.2 Raumladungsverteilung 2.3.3 Oberflächendeformation 2.3.4 Dynamik der Ladungen und des Feldes 3 Messungen 3.1 Proben 3.1.1 Ptychographische Teststruktur 3.1.2 LiNbO3:Fe 3.2 Versuchsanordnung 3.2.1 Experimenteller Aufbau 3.2.2 Grenze der Ortsauflösung 3.2.3 Charakterisierung des Laserstrahls 3.2.4 Experimentelle Überprüfung der Näherungen 3.3 Dynamik der Brechungsindexänderung 3.4 Polarisationsabhängigkeit der Brechungsindexänderung 4 Auswertung 4.1 Dynamik des Raumladungsfeldes und der Ladungen 4.1.1 Simulation 4.1.2 Vergleich zwischen Messung und Simulation 4.1.3 Dynamik der Ladungsverteilung 4.1.4 Fazit 4.2 Berechnung des Raumladungsfeldes 4.2.1 Raumladungsfeld und Ladungsverteilung 4.2.2 Simulation 4.2.3 Asymmetrie der Ladungsverteilung 4.2.4 Fazit 5 Zusammenfassung Appendizes A Physikalische Konstanten B Tensoren für LiNbO3 C Ungenäherte Herleitung der Brechungsindexänderung D Implementierung eines iterativen Verfahrens zur Bestimmung der Dynamik des Ein-Zentrum-Modells E Quelltext der Implementierung des iterativen Verfahrens Literaturverzeichnis

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