Multi-FinGAN: generative coarse-to-fine sampling of multi-finger grasps

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksWhile there exists many methods for manipulating rigid objects with parallel-jaw grippers, grasping with multi- finger robotic hands remains a quite unexplored research topic. Reasoning and planning collision-free trajectories on the additional degrees of freedom of several fingers represents an important challenge that, so far, involves computationally costly and slow processes. In this work, we present Multi-FinGAN, a fast generative multi-finger grasp sampling method that synthesizes high quality grasps directly from RGB-D images in about a second. We achieve this by training in an end-to-end fashion a coarse-to-fine model composed of a classification network that distinguishes grasp types according to a specific taxonomy and a refinement network that produces refined grasp poses and joint angles. We experimentally validate and benchmark our method against a standard grasp-sampling method on 790 grasps in simulation and 20 grasps on a real Franka Emika Panda. All experimental results using our method show consistent improvements both in terms of grasp quality metrics and grasp success rate. Remarkably, our approach is up to 20-30 times faster than the baseline, a significant improvement that opens the door to feedback-based grasp re-planning and task informative grasping. Code is available at https://irobotics.aalto.fi/multi-fingan/.Peer ReviewedPostprint (author's final draft

Linear and Nonlinear Characterizations of Chalcogenide Photonic Crystal Fibers

International audienceIn this paper, we investigate the linear and nonlinear properties of GeSbS and AsSe chalcogenide photonic crystal fibers. Through several experimental setups, we have measured the second- and third-order chromatic dispersion, the effective area, losses, birefringence, the nonlinear Kerr coefficient as well as Brillouin and Raman scattering properties

Sensitivity of L-band vegetation optical depth to carbon stocks in tropical forests: a comparison to higher frequencies and optical indices

Supplementary data to this article can be found online at https://doi.org/10.1016/j.rse.2019.111303.Monitoring vegetation carbon in tropical regions is essential to the global carbon assessment and to evaluate the actions oriented to the reduction of forest degradation. Mainly, satellite optical vegetation indices and LiDAR data have been used to this purpose. These two techniques are limited by cloud cover and are sensitive only to the top of vegetation. In addition, the vegetation attenuation to the soil microwave emission, represented by the vegetation optical depth (VOD), has been applied for biomass estimation using frequencies ranging from 4 to 30¿GHz (C- to K-bands). Atmosphere is transparent to microwaves and their sensitivity to canopy layers depends on the frequency, with lower frequencies having greater penetration depths. In this regard, L-band VOD (1.4¿GHz) is expected to enhance the ability to estimate carbon stocks. This study compares the sensitivity of different VOD products (from L, C, and X-bands) and an optical vegetation index (EVI) to the above-ground carbon density (ACD). It quantifies the contribution of ACD and forest cover proportion to the VOD/EVI signals. The study is conducted in Peru, southern Colombia and Panama, where ACD maps have been derived from airborne LiDAR. Results confirm the enhanced sensitivity of L-band VOD to ACD when compared to higher frequency bands, and show that the sensitivity of all VOD bands decreases in the densest forests. ACD explains 34% and forest cover 30% of L-band VOD variance, and these proportions gradually decrease for EVI, C-, and X-band VOD, respectively. Results are consistent through different categories of altitude and carbon density. This pattern is found in most of the studied regions and in flooded forests. Results also show that C-, X-band VOD and EVI provide complementary information to L-band VOD, especially in flooded forests and in mountains, indicating that synergistic approaches could lead to improved retrievals in these regions. Although the assessment of vegetation carbon in the densest forests requires further research, results from this study support the use of new L-band VOD estimates for mapping the carbon of tropical forests.Peer ReviewedPostprint (author's final draft

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Traitement vidéo-assisté des lésions du processus coronoïde médial chez le chien, étude rétrospective pour 50 coudes

Une étude bibliographique sur les lésions du processus coronoïde médial de l'ulna chez le chien souligne notamment que le diagnostic clinique et radiographique de cette affection est délicat et met en perspective l'intérêt incontesté de l'arthroscopie pour cette indication. Par contre l'intérêt thérapeutique de cette technique est contesté dans la littérature. L'auteur présente de plus une étude rétrospective de 50 coudes atteints de lésions du PCM, traités par arthroscopie au service de chirurgie de l'Ecole Vétérinaire de Maisons-Alfort entre juin 1998 et mars 2001. Les résultats cliniques à court terme et à long terme sont comparés aux résultats cliniques de 57 coudes opérés par arthrotomie lors d'une précédente étude menée au service de chirurgie de l'ENVA entre mai 1991 et mai 1997. Les résultats cliniques sont significativement meilleurs à court terme et à long terme pour les chiens traités par arthroscopie. De fait, cette étude conforte notre idée que l'arthroscopie est la méthode de choix pour le diagnostic et le traitement des lésions du processus coronoïde chez le chien. Cependant quel que soit le traitement chirurgical envisagé, l'inévitable évolution arthrosique à long terme assombrit le pronostic de l'affection.MAISONS-ALFORT-Ecole Vétérin (940462302) / SudocSudocFranceF

Interbank Exposures: An Empirical Examination of Systemic Risk in the Belgian Banking System

Robust (cross-border) interbank markets are important for the well functioning of modern financial systems. Yet, a network of interbank exposures may lead to domino effects following the event of an initial bank failure. The "structure" of the interbank market is a potential important driving factor in the risk and impact of interbank contagion. We investigate the evolution of contagion risk for the Belgian banking system over the period 1993-2002 using detailed information on aggregate interbank exposures of individual banks and on large bilateral interbank exposures. We find that a change from a complete structure (where all banks have symmetric links) towards a "multiple money centre" structure (where the money centres are symmetrically linked to some banks, which are themselves not linked together) as well as a more concentrated banking market have decreased the risk and impact of contagion. Moreover, an increase in the proportion of cross-border interbank assets has lowered the risk and impact of local contagion. Yet, this reduction was probably accompanied by an increase in contagion risk generated by foreign banks, although even here the contagion risk appears fairly limited