19 research outputs found
A study on the use of the PACS bolometer arrays for submillimeter ground-based telescopes
A new kind of bolometric architecture has been successfully developed for the
PACS photometer onboard the Herschel submillimeter observatory. These new
generation CCD-like arrays are buttable and enable the conception of large
fully sampled focal planes. We present a feasibility study of the adaptation of
these bolometer arrays to ground-based submillimeter telescopes. We have
developed an electro-thermal numerical model to simulate the performances of
the bolometers under specific ground-based conditions (different wavelengths
and background powers for example). This simulation permits to determine the
optimal parameters for each condition and shows that the bolometers can be
background limited in each transmission window between 200 and 450 microns. We
also present a new optical system that enables to have a maximum absorption of
the bolometer in each atmospheric windows. The description of this system and
measurements are showed.Comment: 9 pages, 12 figures, to be published in the Proceedings of SPIE Vol.
6275, "Astronomical Telescopes and Instrumentation, Millimeter and
Submillimeter Detectors and Instrumentation for Astronomy III
The ArT\'eMiS wide-field submillimeter camera: preliminary on-sky performances at 350 microns
ArTeMiS is a wide-field submillimeter camera operating at three wavelengths
simultaneously (200, 350 and 450 microns). A preliminary version of the
instrument equipped with the 350 microns focal plane, has been successfully
installed and tested on APEX telescope in Chile during the 2013 and 2014
austral winters. This instrument is developed by CEA (Saclay and Grenoble,
France), IAS (France) and University of Manchester (UK) in collaboration with
ESO. We introduce the mechanical and optical design, as well as the cryogenics
and electronics of the ArTeMiS camera. ArTeMiS detectors are similar to the
ones developed for the Herschel PACS photometer but they are adapted to the
high optical load encountered at APEX site. Ultimately, ArTeMiS will contain 4
sub-arrays at 200 microns and 2x8 sub-arrays at 350 and 450 microns. We show
preliminary lab measurements like the responsivity of the instrument to hot and
cold loads illumination and NEP calculation. Details on the on-sky
commissioning runs made in 2013 and 2014 at APEX are shown. We used planets
(Mars, Saturn, Uranus) to determine the flat-field and to get the flux
calibration. A pointing model was established in the first days of the runs.
The average relative pointing accuracy is 3 arcsec. The beam at 350 microns has
been estimated to be 8.5 arcsec, which is in good agreement with the beam of
the 12 m APEX dish. Several observing modes have been tested, like On-The-Fly
for beam-maps or large maps, spirals or raster of spirals for compact sources.
With this preliminary version of ArTeMiS, we concluded that the mapping speed
is already more than 5 times better than the previous 350 microns instrument at
APEX. The median NEFD at 350 microns is 600 mJy.s1/2, with best values at 300
mJy.s1/2. The complete instrument with 5760 pixels and optimized settings will
be installed during the first half of 2015.Comment: 11 pages, 11 figures. Presented at SPIE Millimeter, Submillimeter,
and Far-Infrared Detectors and Instrumentation for Astronomy VII, June 24,
2014. To be published in Proceedings of SPIE Volume 915
Localized Surface Plasmon Resonance of Metallic Nanoparticles--Optical Property Characterization for Rational Applications
在光的激发下金属纳米结构中的自由电子能够发生群体性的振荡,进而产生表面等离激元(SPP)。发生等离激元共振时,金属纳米结构会将光束缚在表面,并在表面产生极强的电场增强。表面等离激元有两种类型:一类具有传播的特点,其表面等离激元能够在表面传播,称之为propagatingSPP;另一类不具有传播性,共振局域在一个很小的金属结构中,称之为localizedSPP,即局域表面等离激元共振(LSPR)。金属纳米颗粒就具有很强的表面等离激元共振的(LSPR)性质,使其对光产生增强的吸收和增强的散射,并表现出相关的热、光电场增强和热电子等效应。近年,随着纳米科技的发展,金属纳米粒子的LSPR效应已经成为一...The collective oscillation of free electrons in metal nanostructures excited with light is called surface plasmon polaritons (SPP). The light will be confined to a small area on the surface under the resonance condition (SPR), thus a giant enhancement in the electric field will be produced. There are two kinds of surface plasmon polaritons (SPP): one is propagating plasmon polaritons (PSPP), which...学位:理学博士院系专业:化学化工学院_物理化学(含化学物理)学号:2052010015366
Etude de faisabilité d'une caméra bolométrique pour l'imagerie à haute résolution spatiale à 1,3mm de longueur d'onde pour l'IRAM
This thesis lies within the scope of new generation continuum instrumentation for ground-based millimeter astronomy (atmospheric band at 1,3mm). A new type of fully sampling detectors covering the entire focal plane of the 30m IRAM telescope is proposed, based on the development of submillimeter bolometers for the European project Herschel. After an introduction to millimeter astronomy and the principal existing ground-based instruments, a numerical model simulating the behaviour of these bolometers is proposed with the aim to estimate their performances (validated by measurements). The transposition of the absorption peak from 100 microns to 1.3mm is then studied, giving place to the invention of a method based on anti-reflecting layers. The principle was confirmed by spectrometry. The observing process with a ground-based camera using these bolometers is then simulated and shows that a very good pixel sensitivity is possible (10 mJy.s^0.5).Cette thèse s'inscrit dans le cadre de l'instrumentation continuum de nouvelle génération pour l'astronomie millimétrique depuis le sol (bande atmosphérique à 1.3 mm de longueur d'onde). Un nouveau type de détecteurs remplissant entièrement le plan focal du télescope de 30m de l'IRAM de façon optimale est proposé, basé sur le développement de bolomètres submillimétriques pour le projet européen Herschel. Après une introduction à l'astronomie millimétrique et à ses principaux instruments existants au sol, un modèle numérique simulant le fonctionnement de ces bolomètres est proposé dans le but d'estimer leurs performances (validées ensuite par plusieurs mesures). La transposition du pic d'absorption de 100 microns vers 1.3 mm est ensuite étudiée, donnant lieu à l'invention d'une méthode basée sur l'utilisation de couches anti-reflets (principe confirmé par spectrométrie). Le processus d'observation depuis le sol par une caméra utilisant ces bolomètres est ensuite simulé et montre qu'une très bonne sensibilité par pixel est envisageable (environ 10 mJy.s^0.5
Etude de faisabilité d'une caméra bolométrique pour l'imagerie à haute résolution spatiale à 1,3 mm de longueur d'onde, pour l'IRAM
PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
Influence de la pré-éclampsie sur la pression artérielle du nouveau-né en période néonatale
Plusieurs études ont montré que le nouveau né de mère pré-éclamptique présentait un statut hémodynamique particulier caractérisé par des pressions artérielles plus hautes. Cependant, ces études étaient limitées soit à une comparaison dans une population ciblée aux petits poids de naissance ( à 29 SA et de poids >= à 1350 grammes avaient une valeur moyenne et minimale de la pression artérielle diastolique supérieure à celles des nouveaux nés de mère non pré-éclamptique. La valeur minimale de la pression artérielle moyenne était à la limite de la significativité entre les deux groupes. Les valeurs maximales de pression artérielle n'étaient pas différentes entre les 2 groupes. Les pressions artérielles systolique, diastolique et moyenne étaient plus élevées en fonction du temps pour les 2 groupes.LIMOGES-BU Médecine pharmacie (870852108) / SudocSudocFranceF
Method of Generating Commands for Controlling Coordination of Displacement Members of a Moving Platform and Corresponding Generator
US Patent App. 14/125,48
Method of Generating Commands for Controlling Coordination of Displacement Members of a Moving Platform and Corresponding Generator
US Patent App. 14/125,48
Locomotor-feeding coupling during prey capture in a lizard (Gerrhosaurus major): effects of prehension mode
International audienceIn tetrapods, feeding behaviour in general, and prey capture in particular, involves two anatomical systems: the feeding system and the locomotor system. Although the kinematics associated with the movements of each system have been investigated in detail independently, the actual integration between the two systems has received less attention. Recently, the independence of the movements of the jaw and locomotor systems was reported during tongue-based prey capture in an iguanian lizard (Anolis carolinensis), suggesting a decoupling between the two systems. Jaw prehension, on the other hand, can be expected to be dependent on the movements of the locomotor system to a greater degree. To test for the presence of functional coupling and integration between the jaw and locomotor systems, we used the cordyliform lizard Gerrhosaurus major as a model species because it uses both tongue and jaw prehension. Based on a 3-D kinematic analysis of the movements of the jaws, the head, the neck and the forelimbs during the approach and capture of prey, we demonstrate significant correlations between the movements of the trophic and the locomotor systems. However, this integration differs between prehension modes in the degree and the nature of the coupling. In contrast to our expectations and previous data for A. carolinensis, our data indicate a coupling between feeding and locomotor systems during tongue prehension. We suggest that the functional integration between the two systems while using the tongue may be a consequence of the relatively slow nature of tongue prehension in this species
Separating the effects of prey size and speed on the kinematics of prey capture in the omnivorous lizard Gerrhosaurus major
International audienceFeeding behavior is known to be modulated as prey properties change. During prey capture, external prey properties, including size and mobility, are likely some of the most important components in predator–prey interactions. Whereas prey size has been demonstrated to elicit modulation of jaw movements during capture, how prey speed affects the approach and capture of prey remains unknown. We quantified the kinematics associated with movements of both the feeding and locomotor systems during prey capture in a lizard, Gerrhosaurus major, while facing prey differing in size and mobility (newborn mice, grasshoppers, and mealworms). Our data show that the feeding and locomotor systems were recruited differently in response to changes in the size or speed of the prey. The timing of jaw movements and of the positioning of the head are affected by changes in prey size—and speed, to a lesser extent. Changes in prey speed resulted in concomitant changes in the speed of strike and an early and greater elevation of the neck. External prey properties, and prey mobility in particular, are relevant in predator–prey interactions and elicit specific responses in different functional systems