Search

Pour une pathologie donnée, afin de différencier les patients avec un premier évènement aigu (i.e. patients incidents) de ceux présentant une récidive, il est nécessaire de regarder sur une période rétrospective (période de recul) si l’évènement a déjà eu lieu. L'objectif était d'estimer l'impact de la durée de la période de recul sur le nombre de patients identifiés avec un premier évènement d'accident vasculaire cérébrale aigu (AVC) ou de syndrome coronarien aigu (SCA).

L’organisation de la continuité des soins initiés en hospitalisation est primordiale. Concernant les anti-infectieux, les circuits de délivrance sont différents d’une spécialité à une autre et parfois peu lisibles. À ce jour, aucune liste exhaustive et actualisée ne recensait leur modalité de mise à disposition afin d’anticiper la disponibilité du médicament en sortie d’hospitalisation.

Fluorescent organic molecules have received great attention due to their largest applications, for example, in DNA and RNA spectroscopies studies, development of new photoluminescence bioprobes, and applications in fluorescence spectroscopy. In specific, purine base analog molecules present high fluorescence quantum yields and significant Stokes shift. Furthermore, the addition of push–pull structures at the purine core could increase the photoluminescence properties, making candidates for photoluminescence bioprobes. To consider this, a complete spectroscopic study was performed on nine push–pull purines, distinguished by different push–pull structures. In specific, for this research, the two-photon absorption (2PA) study showed that the compounds present induced two-photon fluorescence at the therapeutic window, desired for fluorescence microscopy. The brightness property was evaluated, indicating that all chromospheres are fluorescent by a 2PA process. Additionally, ultrafast transient absorption was performed to elucidate contribution of the excited states on the 2PA spectra, and quantum chemistry calculations were performed to corroborate the experimental results.

Une large sélection d'outils sont disponibles pour analyser les données de survie avec un traitement qui varie au cours du temps. L'analyse en intention de traiter, avec la considération du traitement initial, permet une compréhension simple de l'analyse mais n'est pas la seule alternative. L'objectif de cette étude est de décrire la méthodologie et l'interprétation de modèles de survie en prenant en compte une exposition au traitement qui varie au cours du temps.

Les bases de données médico-administratives, largement utilisées pour estimer l'incidence des pathologies, ne contiennent pas la date du diagnostic clinique. Parmi les patients identifiés avec la pathologie sur la période d'inclusion, ceux ne présentant pas de critère d'identification de la pathologie durant une certaine période avant la date index, appelée période sans maladie, sont considérés incidents. En raison de la limitation des données, cette période est souvent restreinte à 1, 2 ou 3 ans. L'objectif de ce travail était d'estimer l'impact de la durée de la période sans maladie sur l'incidence de population immunodéprimée dans l’étude Covarisq à partir des données du SNDS.

Les gestionnaires de périmètres irrigués sont souvent confrontés à des problèmes d'ensablement. Dans le cadre d'un programme mené au Pakistan, il nous a été demandé de procurer à ces gestionnaires un nouvel outil de diagnostic du fonctionnement de leurs réseaux, prenant en compte ces problèmes sédimentaires. Les objectifs de notre travail sont donc de développer des méthodologies pour représenter et interpréter les phénomènes de dépôt solide dans ces périmètres. Notre approche se base sur l’analyse des données hydrauliques et sédimentaires collectées sur un périmètre irrigué réel. La première partie de nos travaux consiste à sélectionner un jeu minimum de paramètres physiques qui permettent de représenter les phénomènes observés, et à proposer une méthode de partition du réseau en biefs homogènes. Nous identifions ensuite des lois génériques de comportement des dépôts pour les différents niveaux du système. Les paramètres de ces lois sont calés sur des dynamiques réelles de dépôt dans les canaux d’un périmètre irrigué de la province du Sindh (Pakistan), sur la base de données observées sur plusieurs années et sur une campagne de mesures spécifiques par traceurs radioactivables. A l'issue de cette analyse, nous proposons un modèle sédimentaire global, pouvant être assimilé au résultat d’une approche systémique bâtie sur les bases physique de la mécanique des fluides et du transport solide.

Les facteurs de confusion non mesurés sont une source de biais dans les études observationnelles. Les méthodes de contrôle de ces facteurs peuvent intervenir au stade du design de l’étude et de l'analyse.

Digital interference microscopy is a new measuring technique with submicron horizontal resolution and nanometric vertical resolution, that can be used for the three-dimensional analysis of surface defects and device features in many microelectronics applications on bulk materials and epitaxial layers. In this paper we show how certain defects can be analysed on III-V materials and devices using two different interferometric techniques. The choice of the technique depends on the height and the slope of the surface features to be measured. We show that small defects less than λ/2 in height, or surfaces with shallow continuous slopes upto one or two microns high are best profiled with the phase stepping technique (PSM) because of the high vertical resolution of 1 nm and the higher speed and precision. This is illustrated by studies of the surface polish of InP wafers, defects after chemical etching of tin doped InP, defects on an epitaxial layer of GaAs on InP and quantum dot structures on GaAs. For measuring devices which contain mesas and grooves with step heights greater than λ/2, the peak fringe scanning (PFSM) method is the better choice. The vertical resolution is slightly less (4 nm), but the vertical range is higher (upto 15 μm) as demonstrated with the measurement of an etched groove in a laser/detector device on a quaternary layer on InP, and a MESFET device on GaAs. Compared with electron microscopy and the new near field scanning techniques, digital interference microscopy has the advantages of ease of use and speed of analysis and being able to resolve certain problems that are difficult or not possible by other means, such as profiling deep narrow etched grooves, or measuring the relief of a surface hidden under a transparent layer. The main disadvantages are that the horizontal resolution is limited to the resolving power of the objective and that errors due to variations in the optical properties of the sample need to be taken into account.

In this work we describe comparatively the fabrication and the characterization of various types of HTS Josephson junctions manufactured using different processes : grain boundary junctions have been studied both by the way of junctions on bicrystal substrates and of bi-epitaxial junctions. Ramp-edge types have been elaborated and characterized using mainly N-YBaCuO thin film as a barrier while the trilayer approach has been investigated through a-axis structures. YBaCuO or GdBaCuO superconductive films, insulator layers, barriers, buffer and seed layers are deposited using inverted cylindrical magnetron (ICM) sputtering or pulsed laser deposition (PLD) techniques. Most of these junction configurations have been improved either on SrTiO3, MgO, LaAlO3or on more conventional R-plane sapphire substrates. Technology process involving optical lithography and Ar ion beam milling are used up to two inch wafers (sapphire). Emphasis has been put on the optimization of the device processing procedures and their reliabilities in the aim of high temperature superconducting electronics. Structural and morphological characterizations, SEM and TEM observations have been realized in order to improve the junction processes. All the obtained devices were electrically and optically tested including under applied microwaves (Shapiro steps), magnetic field diffraction and light irradiation (infrared detection). Most of the results evidence a resistively-shunted junction (RSJ) behaviour up to ≈ 77K (except for very high current density values). Potentiality of each HTS thin film device structure will be comparatively discussed.

The synthesis of 8‐amido‐ and 8‐aminopurines by a single palladium‐catalyzed protocol is reported. The method proceeds efficiently and tolerates a wide range of amides and amines as coupling partners, including aryl, alkyl, sulfone, and acetal amides, as well as deactivated m‐ and p‐nitroanilines. In this way, a library of new 6,8,9‐trisubstituted purines has been synthesized.

Fluid flows within "T" or "Y" shaped microchannels are deeply studied in order to develop adapted modeling approaches and experimental techniques. Our technological choice lies on the attenuation measurement of X-ray in matter. The main advantage of this non-intrusive technique is to be implemented on medias opaque to visible light. Moreover, X-rays methods may achieve better spatial resolutions as compared to optical methods because of their much lower wavelength. In order to validate this X-ray method, measurements obtained by this technique are compared with direct measurements carried out on similar microchannels. Finally, experimental results are compared with a theoretical model.

We have developed a white-light interference microscope for ultrahigh-resolution full-field optical coherence tomography of biological media. The experimental setup is based on a Linnik-type interferometer illuminated by a tungsten halogen lamp. En face tomographic images are calculated by a combination of interferometric images recorded by a high-speed CCD camera. Spatial resolution of 1.8 μm × 0.9 μm (transverse × axial) is achieved owing to the extremely short coherence length of the source, the compensation of dispersion mismatch in the interferometer arms, and the use of relatively high-numerical-aperture microscope objectives. A shot-noise-limited detection sensitivity of 90 dB is obtained in an acquisition time per image of 4 s. Subcellular-level images of plant, animal, and human tissues are presented.

New instrumentation has been developed that is dedicated to the measurement of surface morphology with high resolutions and short acquisition times. Sinusoidal phase-shifting interferometry is demonstrated to provide within an acquisition time of only a few milliseconds topographic images with ~1 nm height precision, ~1 $\mu$m lateral resolution, and a few tens of pm sensitivity. A white-light scanning microscope is also under development, using an in-house developed high speed, intelligent CCD camera, the first tests of which demonstrate the feasibility of providing topographic images of deep surface relief (several microns to several tens of microns) within less than 0.3 s. The useful lateral field of view can be extended by employing image ”stitching" while maintaining a high lateral resolution.

We describe an original microscope for high-resolution optical coherence tomography applications. Our system is based on a Linnik interference microscope with high-numerical-aperture objectives. Lock-in detection of the interference signal is achieved in parallel on a CCD by use of a photoelastic birefringence modulator and full-field stroboscopic illumination with an infrared LED. Transverse cross-section (en-face, or XY) images can be obtained in real time with better than 1-µm axial (Z) resolution and 0.5-µm transverse (XY) resolution. A sensitivity of ∼80 dB is reached at a 1-image/s acquisition rate, which allows tomography in scattering media such as biological tissues.