Eclipses of the inner satellites of Jupiter observed in 2015

During the 2014-2015 campaign of mutual events, we recorded ground-based photometric observations of eclipses of Amalthea (JV) and, for the first time, Thebe (JXIV) by the Galilean moons. We focused on estimating whether the positioning accuracy of the inner satellites determined with photometry is sufficient for dynamical studies. We observed two eclipses of Amalthea and one of Thebe with the 1 m telescope at Pic du Midi Observatory using an IR filter and a mask placed over the planetary image to avoid blooming features. A third observation of Amalthea was taken at Saint-Sulpice Observatory with a 60 cm telescope using a methane filter (890 nm) and a deep absorption band to decrease the contrast between the planet and the satellites. After background removal, we computed a differential aperture photometry to obtain the light flux, and followed with an astrometric reduction. We provide astrometric results with an external precision of 53 mas for the eclipse of Thebe, and 20 mas for that of Amalthea. These observation accuracies largely override standard astrometric measurements. The (O-C)s for the eclipse of Thebe are 75 mas on the X-axis and 120 mas on the Y-axis. The (O-C)s for the total eclipses of Amalthea are 95 mas and 22 mas, along the orbit, for two of the three events. Taking into account the ratio of (O-C) to precision of the astrometric results, we show a significant discrepancy with the theory established by Avdyushev and Ban'shikova in 2008, and the JPL JUP 310 ephemeris.Comment: 7 pages, 10 figures, 4 table

Polarization state of the optical near-field

The polarization state of the optical electromagnetic field lying several nanometers above complex dielectric structures reveals the intricate light-matter interaction that occurs in this near-field zone. This information can only be extracted from an analysis of the polarization state of the detected light in the near-field. These polarization states can be calculated by different numerical methods well-suited to near--field optics. In this paper, we apply two different techniques (Localized Green Function Method and Differential Theory of Gratings) to separate each polarisation component associated with both electric and magnetic optical near-fields produced by nanometer sized objects. The analysis is carried out in two stages: in the first stage, we use a simple dipolar model to achieve insight into the physical origin of the near-field polarization state. In the second stage, we calculate accurate numerical field maps, simulating experimental near-field light detection, to supplement the data produced by analytical models. We conclude this study by demonstrating the role played by the near-field polarization in the formation of the local density of states.Comment: 9 pages, 11 figures, accepted for publication in Phys. Rev.

Éditorial

Au moment où paraît la quatorzième livraison de La Revue, la BNU vient d’inaugurer sa première « saison culturelle », au sens que nous souhaitons désormais donner à une programmation établie à l’avance. Celle-ci repose notamment sur un certain nombre de cycles issus des partenariats que la bibliothèque souhaite étendre avec des institutions qui, comme elle, contribuent à la valorisation aussi bien de la création artistique que de la réflexion intellectuelle : Théâtre national de Strasbourg, c..

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Ce printemps 2017 a vu arriver deux très bonnes nouvelles pour la Bibliothèque nationale et universitaire de Strasbourg. La première concerne directement La Revue de la BNU, puisque celle-ci vient d’être admise au sein de revues.org, portail de référence pour les revues en sciences humaines et sociales, admission que nous voyons comme une reconnaissance du positionnement de notre publication et au-delà, de notre politique scientifique et de valorisation du très riche patrimoine dont nous avon..

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En ce printemps d’élections européennes, nous voudrions souligner l’importance, pour les établissements d’éducation, de recherche et de culture, des partenariats internationaux. Car ce numéro, placé d’emblée sous une double appartenance géographique, est d’abord le fruit d’un partenariat, celui qui unit depuis 2011 la Bibliothèque nationale de Lettonie et la Bibliothèque nationale et universitaire de Strasbourg et qui a déjà permis plus d’une réalisation : ne citons que les expositions, conçu..

Influence of Biological Factors on Connectivity Patterns for Concholepas concholepas (loco) in Chile

In marine benthic ecosystems, larval connectivity is a major process influencing the maintenance and distribution of invertebrate populations. Larval connectivity is a complex process to study as it is determined by several interacting factors. Here we use an individual-based, biophysical model, to disentangle the effects of such factors, namely larval vertical migration, larval growth, larval mortality, adults fecundity, and habitat availability, for the marine gastropod Concholepas concholepas (loco) in Chile. Lower transport success and higher dispersal distances are observed including larval vertical migration in the model. We find an overall decrease in larval transport success to settlement areas from northern to southern Chile. This spatial gradient results from the combination of current direction and intensity, seawater temperature, and available habitat. From our simulated connectivity patterns we then identify subpopulations of loco along the Chilean coast, which could serve as a basis for spatial management of this resource in the future

Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. We used classical dense photometric lightcurves from several sources and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetics and observed pole-latitude distributions, we were able to constrain the typical values of the cYORP parameter as between 0.05 and 0.6.Comment: Accepted for publication in A&A, January 15, 201

Electrically activated W-doped VO2 films for reli-able, large-area, broadband THz waves modulators

THz amplitude modulators and switches are considered to be the main building blocks of future THz communication systems. Despite rapid progress, modulation and switching devices in this electromagnetic spectrum lag far behind other frequency ranges. Currently, THz modu-lators face major challenges in consistently producing high modulations depths over large frequency bands. Moreover, a convenient integration for practical applications requires that the modulation/switching properties can be electrically controlled. Devices fulfilling all these con-ditions remain to be demonstrated. In this work we show that W-doped VO2 films grown by direct-current magnetron sputtering can be efficiently used for the development reliable, large-area, broadband THz waves modulators. We demonstrate that W doping not only permits to tune the insulator to metal transition (IMT) temperature of VO2, but also, most importantly, to control the topology of the electrically activated transition. In situ / operando X-ray diffraction and Raman spectroscopy characterizations of the devices, coupled with standard resistivi-ty measurements and time-domain THz spectroscopy, unambiguously demonstrate that the changes in the spatial distribution of the IMT is due to structural distortions induced by W doping

Light models intercomparison in agriVoltaics context

Reduction of greenhouse gas emissions is one of the major issues facing our society when the population of the world is set to rise to 9.1 billion by 2050, 34 percent more than today. In this context, research is being conducted to develop new efficient, resilient and sustainable agricultural production systems based on agroecology but also integrating agrivoltaism concept. If these Agrivoltaics systems (agri-PV) can be efficient for some productions in favorable soil and climatic contexts, solutions still need to be developed to guarantee synergy between energy production and agronomic yield for many markets gardening, cereal or arboriculture crops as well as for livestock. Light is one of the major variables that needs to be characterised in order to analyse the conditions of synergy, as it is the main environmental factor involved in Photovoltaic (PV) system functioning and in the biophysical processes of crops, such as photosynthesis, evapotranspiration and photomorphogenesis, which are involved in plant growth and development. Because of climate variations from one year to the next [1], experiments should be conducted over several years in order to draw some conclusions. To address such problem, we propose to share the different datasets acquired during the various agri-PV experiments to allow robust statistical analysis. Moreover, analysis of light availability is not only based on measurements but also on the use of light models. These models are based on the same approach in both cases for the PV systems and the crops. Therefore, it exists different models (for instance based on raytracing or radiosity methods) that rely on similar assumptions regarding input data such as the characterisation of the concerned PV system and the physical modelling of incident irradiance (e.g., diffuse and direct radiation computation). As part of a collaborative approach of data sharing to analyse the conditions for synergy between the two productions, it becomes determinant do evaluate the precision of the different models. This kind of intercomparison was done in the research topics of remote sensing with the RAMI project [2] or in plant ecophysiology [3]. In these examples, no measurements were used because one model was considered as a reference model. In the present study, the objective is to quantify the precision of light models by simulating light below different configurations of agri-PV systems and compare them with actual measurements. The comparison will highlight the differences in physical modelling assumptions between the models and will include an estimate of biases and errors, as well as efficiency in terms of computational time