ZAP -- Enhanced PCA Sky Subtraction for Integral Field Spectroscopy

We introduce Zurich Atmosphere Purge (ZAP), an approach to sky subtraction based on principal component analysis (PCA) that we have developed for the Multi Unit Spectrographic Explorer (MUSE) integral field spectrograph. ZAP employs filtering and data segmentation to enhance the inherent capabilities of PCA for sky subtraction. Extensive testing shows that ZAP reduces sky emission residuals while robustly preserving the flux and line shapes of astronomical sources. The method works in a variety of observational situations from sparse fields with a low density of sources to filled fields in which the target source fills the field of view. With the inclusion of both of these situations the method is generally applicable to many different science cases and should also be useful for other instrumentation. ZAP is available for download at http://muse-vlt.eu/science/tools.Comment: 12 pages, 7 figures, 1 table. Accepted to MNRA

Suivi tridimensionnel en stéréovision

Cet article présente une méthode d'estimation en temps réel de la trajectoire d'une cible en trois dimensions, appliquée au suivi d'un doigt de la main dans un contexte de reconnaissance de gestes. Notre approche est basée sur la vision stéréoscopique, avec deux caméras standards, de type webcams. La main est segmentée par soustraction du fond, et le bout du doigt est détectée avec l'analyse de la courbure du contour. Le suivi du doigt est réalisé par un filtrage de Kalman tridimensionnel, ce qui permet d'améliorer la détection avec une recherche locale basée sur la prédiction de la position 3D et de filtrer la trajectoire pour réduire l'erreur d'estimation

The MUSE Extremely Deep Field: The cosmic web in emission at high redshift

We report the discovery of diffuse extended Lyα emission from redshift 3.1 to 4.5, tracing cosmic web filaments on scales of 2.5-4 cMpc. These structures have been observed in overdensities of Lyα emitters in the MUSE Extremely Deep Field, a 140 h deep MUSE observation located in the Hubble Ultra-Deep Field. Among the 22 overdense regions identified, five are likely to harbor very extended Lyα emission at high significance with an average surface brightness of 5  ×  10-20 erg s-1 cm-2 arcsec-2. Remarkably, 70% of the total Lyα luminosity from these filaments comes from beyond the circumgalactic medium of any identified Lyα emitter. Fluorescent Lyα emission powered by the cosmic UV background can only account for less than 34% of this emission at z  ≈  3 and for not more than 10% at higher redshift. We find that the bulk of this diffuse emission can be reproduced by the unresolved Lyα emission of a large population of ultra low-luminosity Lyα emitters (< 1040 erg s-1), provided that the faint end of the Lyα luminosity function is steep (α ⪅ -1.8), it extends down to luminosities lower than 1038 -  1037 erg s-1, and the clustering of these Lyα emitters is significant (filling factor < 1/6). If these Lyα emitters are powered by star formation, then this implies their luminosity function needs to extend down to star formation rates < 10-4M yr-1. These observations provide the first detection of the cosmic web in Lyα emission in typical filamentary environments and the first observational clue indicating the existence of a large population of ultra low-luminosity Lyα emitters at high redshift. © R. Bacon et al. 2021

Dark galaxy candidates at redshift∼ 3.5 detected with MUSE

Recent theoretical models suggest that the early phase of galaxy formation could involve an epoch when galaxies are gas rich but inefficient at forming stars: a “dark galaxy” phase. Here, we report the results of our Multi-Unit Spectroscopic Explorer (MUSE) survey for dark galaxies fluorescently illuminated by quasars at z > 3. Compared to previous studies which are based on deep narrowband (NB) imaging, our integral field survey provides a nearly uniform sensitivity coverage over a large volume in redshift space around the quasars as well as full spectral information at each location. Thanks to these unique features, we are able to build control samples at large redshift distances from the quasars using the same data taken under the same conditions. By comparing the rest-frame equivalent width (EW0) distributions of the Lyα sources detected in proximity to the quasars and in control samples, we detect a clear correlation between the locations of high-EW0 objects and the quasars. This correlation is not seen in other properties, such as Lyα luminosities or volume overdensities, suggesting the possible fluorescent nature of at least some of these objects. Among these, we find six sources without continuum counterparts and EW0 limits larger than 240 Å that are the best candidates for dark galaxies in our survey at z > 3.5. The volume densities and properties, including inferred gas masses and star formation efficiencies, of these dark galaxy candidates are similar to those of previously detected candidates at z ≈ 2.4 in NB surveys. Moreover, if the most distant of these are fluorescently illuminated by the quasar, our results also provide a lower limit of t = 60 Myr on the quasar lifetime.peer-reviewe

A prospective international multi-center study on safety and efficacy of deep brain stimulation for resistant obsessive-compulsive disorder

Deep brain stimulation (DBS) has been proposed for severe, chronic, treatment-refractory obsessive-compulsive disorder (OCD) patients. Although serious adverse events can occur, only a few studies report on the safety profile of DBS for psychiatric disorders. In a prospective, open-label, interventional multi-center study, we examined the safety and efficacy of electrical stimulation in 30 patients with DBS electrodes bilaterally implanted in the anterior limb of the internal capsule. Safety, efficacy, and functionality assessments were performed at 3, 6, and 12 months post implant. An independent Clinical Events Committee classified and coded all adverse events (AEs) according to EN ISO14155:2011. All patients experienced AEs (195 in total), with the majority of these being mild (52% of all AEs) or moderate (37%). Median time to resolution was 22 days for all AEs and the etiology with the highest AE incidence was 'programming/stimulation' (in 26 patients), followed by 'New illness, injury, condition' (13 patients) and 'pre-existing condition, worsening or exacerbation' (11 patients). Sixteen patients reported a total of 36 serious AEs (eight of them in one single patient), mainly transient anxiety and affective symptoms worsening (20 SAEs). Regarding efficacy measures, Y-BOCS reduction was 42% at 12 months and the responder rate was 60%. Improvements in GAF, CGI, and EuroQol-5D index scores were also observed. In sum, although some severe AEs occurred, most AEs were mild or moderate, transient and related to programming/stimulation and tended to resolve by adjustment of stimulation. In a severely treatment-resistant population, this open-label study supports that the potential benefits outweigh the potential risks of DBS

The Choice of Ignorance: The Debate on Ethnic and Racial Statistics in France

A researcher or a journalist trying to compare the situation of ethnic and racial minorities in the United States and in France immediately confronts a crippling obstacle. The concept of ‘ethnic and racial minority’ as such is not used in France. This is not simply a matter of vocabulary –something the French typically like to argue about; the problem rather lies in the very incomparability of populations that one is talking about. Many of the categories that do exist in political discourse and public debate can of course be found in statistics. But there are no data describing the situation of minorities in France that could be compared with those produced in the United States. This state of affairs in French statistics – gathering has been the subject of major criticism for some 20 years now; it has gotten to the point that it has triggered a controversy of rare violence between those that would like to see statistics take into account the diversity of the population and those who denounce the danger that such statistics might pose of ethnicizing or racializing society. The media focus on the contentiousness of this debate has been such as to sometimes lose sight of the very existence of discrimination and the flaws of the Republican model that are at the root of the controversy in the first place

Suivi tridimensionnel de la main et reconnaissance de gestes pour les Interfaces Homme Machine

Automatic interpretation of gestures based on computer vision provides new possibilities of interaction with computers, more natural and intuitive than with classic devices. However, the gestural channel is a particularly rich means of communication and the hand is a complex articulated object. Thus, gesture-based human-computer interaction represents a particularly active research axis with an important potential of application. In this context, our work consisted in replacing the mechanism of a tactile screen by a system based on stereoscopic vision with two video cameras. Thus, the central issue consisted in tracking in real-time the movement of the hand and the fingers based on their projections on images, and in recognizing the posture. The industrial constraints which guided our work lead us to an appearance-based approach, with reduced hypothesis so that the system is little restrictive for the user. The different steps we address concern hand detection based on skin color, extraction of invariant features, comparison of shape descriptors for 2D posture recognition, and 3D finger and hand tracking with a skeleton model. The performances of the algorithms was evaluated with an original database of stereoscopic video sequences, showing the noticeable improvement of the proposed solutions. The system's robustness was confronted to real conditions with a public demonstration.L'interprétation automatique de gestes basée sur la vision par ordinateur offre de nouvelles possibilités d'interaction avec l'ordinateur, plus naturelles et intuitives qu'avec les périphériques classiques. Cependant, le canal gestuel est un moyen de communication particulièrement riche et la main un objet articulé complexe. Ainsi, l'interaction homme-machine gestuelle constitue un axe de recherche particulièrement actif avec un potentiel applicatif important. Dans ce contexte, notre travail a consisté à remplacer le fonctionnement d'un écran tactile par un système de vision stéréoscopique avec deux caméras. Ainsi, le problème fondamental a consisté à suivre, en temps réel, le mouvement de la main et des doigts à partir de leurs projections dans les images, avant d'en reconnaître la posture. Les contraintes industrielles qui ont guidé nos travaux nous ont orienté vers une approche par apparence, avec des hypothèses réduites afin que le système soit peu contraignant pour l'utilisateur. Les différentes étapes abordées concernent la détection de la main basée sur la couleur de peau, l'extraction de caractéristiques invariantes, la comparaison de descripteurs de forme pour la reconnaissance de postures 2D, et le suivi 3D du mouvement des doigts et de la main avec un modèle squelettique. Les algorithmes ont été évalués à l'aide d'une base originale de vidéos stéréoscopiques, montrant l'amélioration notable des solutions proposées. La robustesse du système a également été confrontée aux conditions réelles d'une démonstration publique

Suivi tridimensionnel de la main et reconnaissance de gestes pour les interfaces homme-machine

L interprétation automatique de gestes basée sur la vision par ordinateur offre de nouvelles possibilités d interaction avec l ordinateur, plus naturelles et intuitives qu avec les périphériques classiques. Cependant, le canal gestuel est un moyen de communication particulièrement riche et la main un objet articulé complexe. Ainsi, l interaction homme-machine gestuelle constitue un axe de recherche particulièrement actif avec un potentiel applicatif important. Dans ce contexte, notre travail a consisté à remplacer le fonctionnement d un écran tactile par un système de vision stéréoscopique avec deux caméras. Ainsi, le problème fondamental a consisté à suivre, en temps réel, le mouvement de la main et des doigts à partir de leurs projections dans les images, avant d en reconnaître la posture. Les contraintes industrielles qui ont guidé nos travaux nous ont orienté vers une approche par apparence, avec des hypothèses réduites afin que le système soit peu contraignant pour l utilisateur. Les différentes étapes abordées concernent la détection de la main basée sur la couleur de peau, l extraction de caractéristiques invariantes, la comparaison de descripteurs de forme pour la reconnaissance de postures 2d, et le suivi 3d du mouvement des doigts et de la main avec un modèle squelettique. Les algorithmes ont été évalués à l aide d une base originale de vidéos stéréoscopiques, montrant l amélioration notable des solutions proposées. La robustesse du système a également été confrontée aux conditions réelles d une démonstration publique.AIX-MARSEILLE3-BU Sc.St Jérô (130552102) / SudocSudocFranceF