Accelerated convergence method for fast Fourier transform simulation of coupled cavities

Fast Fourier transform (FFT) simulation was used to calculate the power and spatial distribution of resonant fields in optical cavities. This is an important tool when characterizing the effect of imperfect geometry and mirror aberrations. This method is, however, intrinsically slow when the cavities are of relatively high finesse. When this is the case, an accelerated convergence scheme may be used to calculate the steady-state cavity field with a speed that is orders of magnitude faster. The rate of convergence of this method, however, is unpredictable, as many different factors may detrimentally affect its performance. In addition, its use in multiple cavity configurations is not well understood. An in-depth study of the limitations and optimization of this method is presented, together with a formulation of its use in multiple cavity configurations. This work has not only resulted in consistent improvement in performance and stability of the accelerated convergence method but also allows the simulation of optical configurations, which would not previously have been possible

Molecular evidence for the natural production of homozygous Cupressus sempervirens L. lines by Cupressus dupreziana seed trees

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How Porosity Modifies the Photovoltaic Effect in Nanocrystalline Solar Cells

The porosity of the nanocrystalline semiconductor affects many aspects of the photoconversion process in dye-sensitzed solar cells, thus distinguishing them mechanistically from conventional photovoltaic and photoelectro-chemical cells. We discuss several examples from our recent work

Ultra-Wideband Microwave Imaging of Heterogeneities

International audienceThe technique of time-reversal acoustics was applied to image a bottle filled with saline, using an eight element Vivaldi antenna array with frequency bandwidth 2 to 8 GHz. At these short length scales, a smooth three-dimensional image of the bottle was obtained, with the usual limitations imposed by limited offset and frequency. Time snapshots of the wavefield evolution in reversed time are presented for two real data sets. The first, shows the focusing for the single target of the bottle, while the second demonstrates the principle for two targets

Study of cationic N-isopropylacrylamide-styrene copolymer latex particles using fluorescent probes

Monodisperse cationically charged core-shell poly[styrene/N-isopropylacrylamide] latexes, differing in their shell structure, were studied at temperatures around the lower critical solution temperature (LCST) of poly[N-isopropylacrylamide]. Near the LCST, a transition on the latex dimensions was observed by quasi-elastic light scattering measurements. The same transition could also be detected using the intensity ratio of the pyrene fluorescence vibronic bands, I1/I3, and the excimer to monomer fluorescence intensity ratio of 1,10-bis(1-pyrenyl)decane. The fluorescence spectra and decay curve measurements of 1,10-bis-(1-pyrenyl)decane provided a better understanding of both the hydrophilic-hydrophobic variation and the conformational changes occurring in the poly[N-isopropylacrylamide] shell of the latex particles upon temperature variation.J. M. G. Martinho is grateful for the support of this work from FCT. E. M. S. Castanheira acknowledges FCT for a grant (PRAXIS XXI/BPD/9968/96)

Types de qualification et parcours professionnels des diplômé∙e∙s en sciences du sport. L’exemple des diplômé∙e∙s (2010‐2014) de la faculté des sciences du sport de Strasbourg

Les facultés des sciences du sport ont progressivement diversifié leur offre de formations, notamment en introduisant des formations professionnelles. Cette professionnalisation de l’offre de formation facilite-t-elle l’insertion professionnelle dans le secteur des activités physiques et sportives ? Suffit-elle à pourvoir les diplômé·e·s des compétences requises par les employeurs dans ces secteurs d’activité ? Cette dernière question se pose particulièrement dans le domaine d’emploi de l’intervention en activités physiques et/ou sportives où des qualifications spécifiques – brevets fédéraux ou d’état – constituent parfois des prérequis indispensables. À l’inverse, certain·e·s étudiant·e·s cherchent à consolider leur formation spécifique en activités physiques et sportives avec des qualifications hors du domaine strictement sportif (en management, ressources humaines, commerce de gros et de détail, nutrition, kinésithérapie, etc.). Les parcours de formation dans l’enseignement supérieur – comme les doubles diplômes ou les parcours combinant plusieurs types de qualification – facilitent l’accès à l’emploi dans une forme d’adéquation formation-emploi qu'il convient de questionner. Les niveaux et types de diplômes pèsent-ils sur l’insertion professionnelle ? Existe-t-il d’autres facteurs, extra-scolaires, déterminant une insertion professionnelle satisfaisante ? L’engagement bénévole dans l’encadrement des activités sportives au sein d’associations par exemple constitue-t-il un facteur favorisant l’insertion professionnelle voire à plus long terme les évolutions de carrière ? C’est à ces questions que nous prétendons répondre à travers une recherche locale menée en 2016 qui s’appuie sur des enquêtes quantitatives et qualitatives. Les diplômé·e·s de la faculté des sciences du sport de 2010 à 2014, titulaires de diplôme de niveau bac+2 (DEUST ) à bac+5 (master) ont en effet été interrogé·e·s. Au final, les résultats reposent sur le traitement statistique de 448 questionnaires diplômé·e·s et sur 103 questionnaires renseignés par les employeurs de ces étudiant·e·s diplômé·e·s. Les résultats s’appuient aussi sur l’analyse de contenu thématique des entretiens semi-directifs téléphoniques réalisés auprès de 60 diplômé·e·s. Un complément d’enquête qualitative sera mené au cours du 1er trimestre 2019 pour étoffer les données empiriques concernant les parcours dans l’emploi de ces diplômé·e·s. En combinant des techniques de recueil de données quantitatives et qualitatives (Mahlaoui, 2015), nous nous attachons non seulement à relever les propriétés objectives des diplômé·e·s (caractéristiques des diplômes, situation d’emploi), mais aussi à prendre en compte les subjectivités des acteurs·rices, qui permettent d’éclairer les choix – ou les non choix – des orientations de formation et les chemins individuels d’accès aux emplois

The art of being human : a project for general philosophy of science

Throughout the medieval and modern periods, in various sacred and secular guises, the unification of all forms of knowledge under the rubric of ‘science’ has been taken as the prerogative of humanity as a species. However, as our sense of species privilege has been called increasingly into question, so too has the very salience of ‘humanity’ and ‘science’ as general categories, let alone ones that might bear some essential relationship to each other. After showing how the ascendant Stanford School in the philosophy of science has contributed to this joint demystification of ‘humanity’ and ‘science’, I proceed on a more positive note to a conceptual framework for making sense of science as the art of being human. My understanding of ‘science’ is indebted to the red thread that runs from Christian theology through the Scientific Revolution and Enlightenment to the Humboldtian revival of the university as the site for the synthesis of knowledge as the culmination of self-development. Especially salient to this idea is science‘s epistemic capacity to manage modality (i.e. to determine the conditions under which possibilities can be actualised) and its political capacity to organize humanity into projects of universal concern. However, the challenge facing such an ideal in the twentyfirst century is that the predicate ‘human’ may be projected in three quite distinct ways, governed by what I call ‘ecological’, ‘biomedical’ and ‘cybernetic’ interests. Which one of these future humanities would claim today’s humans as proper ancestors and could these futures co-habit the same world thus become two important questions that general philosophy of science will need to address in the coming years

A roadmap to integrate astrocytes into Systems Neuroscience

Systems Neuroscience is still mainly a neuronal field, despite the plethora of evidence supporting the fact that astrocytes modulate local neural circuits, networks, and complex behaviors. In this article, we sought to identify which types of studies are necessary to establish whether astrocytes, beyond their well-documented homeostatic and metabolic functions, perform computations implementing mathematical algorithms that sub-serve coding and higher-brain functions. First, we reviewed Systems-like studies that include astrocytes in order to identify computational operations that these cells may perform, using Ca$^{2+}$ transients as their encoding language. The analysis suggests that astrocytes may carry out canonical computations in time scales of sub-seconds to seconds in sensory processing, neuromodulation, brain state, memory formation, fear, and complex homeostatic reflexes. Next, we propose a list of actions to gain insight into the outstanding question of which variables are encoded by such computations. The application of statistical analyses based on machine learning, such as dimensionality reduction and decoding in the context of complex behaviors, combined with connectomics of astrocyte-neuronal circuits, are, in our view, fundamental undertakings. We also discuss technical and analytical approaches to study neuronal and astrocytic populations simultaneously, and the inclusion of astrocytes in advanced modeling of neural circuits, as well as in theories currently under exploration, such as predictive coding and energy-efficient coding. Clarifying the relationship between astrocytic Ca$^{2+}$ and brain coding may represent a leap forward towards novel approaches in the study of astrocytes in health and disease.Junior Leader Fellowhip Program by 'la Caixa' Banking Foundation, LCF/BQ/LI18/11630006 BFU2017-85936-P BFU2016-75107-P BFU2016-79735-P FLAGERA-PCIN-2015-162-C02-02 HHMI 55008742 FPU13/05377 NIH R01NS099254 NSF 1604544 Agència de Gestio d’Ajuts Universitaris i de Recerca, 2017 SGR54