Action Tubelet Detector for Spatio-Temporal Action Localization

Current state-of-the-art approaches for spatio-temporal action localization rely on detections at the frame level that are then linked or tracked across time. In this paper, we leverage the temporal continuity of videos instead of operating at the frame level. We propose the ACtion Tubelet detector (ACT-detector) that takes as input a sequence of frames and outputs tubelets, i.e., sequences of bounding boxes with associated scores. The same way state-of-the-art object detectors rely on anchor boxes, our ACT-detector is based on anchor cuboids. We build upon the SSD framework. Convolutional features are extracted for each frame, while scores and regressions are based on the temporal stacking of these features, thus exploiting information from a sequence. Our experimental results show that leveraging sequences of frames significantly improves detection performance over using individual frames. The gain of our tubelet detector can be explained by both more accurate scores and more precise localization. Our ACT-detector outperforms the state-of-the-art methods for frame-mAP and video-mAP on the J-HMDB and UCF-101 datasets, in particular at high overlap thresholds.Comment: 9 page

The Role of Closed Gyres in Setting the Zonal Transport of the Antarctic Circumpolar Current

Eddy-permitting simulations are used to show that basinlike gyres can be observed in the large-scale barotropic flow of a wind-driven channel with a meridional topographic ridge. This is confirmed using both two-layer quasigeostrophic and 25-level primitive equation models at high horizontal resolution. Comparing results from simulations with and without the topographic ridge, it is shown that the zonal baroclinic transport in the channel increases with increasing wind stress when the bottom topography is flat but not when there is a meridional ridge. The saturation of transport for increasing wind occurs in conjunction with the development of recirculating gyres in the large-scale barotropic streamfunction. This suggests that the total circulation can be thought of as a superposition of a gyre mode (which has zero circumpolar transport) and a free circumpolar mode (which contains all of the transport). Basinlike gyres arise in the channel because the topography steers the barotropic streamlines and supports a frictional boundary layer similar to the more familiar ones observed along western boundaries. The gyre mode is thus closely linked with the bottom form stress exerted by the along-ridge flow and provides the sink for the wind momentum input. In this framework, any increase in wind forcing spins a stronger gyre as opposed to feeding the circumpolar transport. This hypothesis is supported with a suite of experiments where key parameters are carried over a wide range: wind stress, wind stress curl, ridge height, channel length, and bottom friction.Mathematics and Climate Research Network (Fellowship)National Science Foundation (U.S.) (Award OCE-1233832

Nucleus-invadopodia duo during cancer invasion 1

International audienceMatrix proteolysis mediated by MT1-MMP facilitates the invasive migration of tumor cells in dense tissues, which otherwise get trapped in the matrix because of limited nuclear deformability. A digest-on-demand response has been identified, which requires nucleus-microtubule linkage through the LINC complex and triggers MT1-1

Quality of life with ivabradine in patients with angina pectoris

Background—To explore the effect of ivabradine on angina-related quality of life (QoL) in patients participating in the Study Assessing the Morbidity–Mortality Benefits of the If Inhibitor Ivabradine in Patients with Coronary Artery Disease (SIGNIFY) QoL substudy. Methods and Results—QoL was evaluated in a prespecified subgroup of SIGNIFY patients with angina (Canadian Cardiovascular Society class score, ≥2 at baseline) using the Seattle Angina Questionnaire and a generic visual analogue scale on health status. Data were available for 4187 patients (2084 ivabradine and 2103 placebo). There were improvements in QoL in both treatment groups. The primary outcome of change in physical limitation score at 12 months was 4.56 points for ivabradine versus 3.40 points for placebo (E, 0.96; 95% confidence interval, –0.14 to 2.05; P=0.085). The ivabradine−placebo difference in physical limitation score was significant at 6 months (P=0.048). At 12 months, the visual analogue scale and the other Seattle Angina Questionnaire dimensions were higher among ivabradine-treated patients, notably angina frequency (P<0.001) and disease perception (P=0.006). Patients with the worst QoL at baseline (ie, those in the lowest tertile of score) had the best improvement in QoL for 12 months, with improvements in physical limitation and a significant reduction in angina frequency (P=0.034). The effect on QoL was maintained over the study duration, and ivabradine patients had better scores on angina frequency at every visit to 36 months. Conclusions—Treatment with ivabradine did not affect the primary outcome of change in physical limitation score at 12 months. It did produce consistent improvements in other self-reported QoL parameters related to angina pectoris, notably in terms of angina frequency and disease perception

Joint learning of object and action detectors

International audienceWhile most existing approaches for detection in videos focus on objects or human actions separately, we aim at jointly detecting objects performing actions, such as cat eating or dog jumping. We introduce an end-to-end multitask objective that jointly learns object-action relationships. We compare it with different training objectives, validate its effectiveness for detecting objects-actions in videos, and show that both tasks of object and action detection benefit from this joint learning. Moreover, the proposed architecture can be used for zero-shot learning of actions: our multitask objective leverages the commonalities of an action performed by different objects, e.g. dog and cat jumping , enabling to detect actions of an object without training with these object-actions pairs. In experiments on the A2D dataset [50], we obtain state-of-the-art results on segmentation of object-action pairs. We finally apply our multitask architecture to detect visual relationships between objects in images of the VRD dataset [24]

Action Tubelet Detector for Spatio-Temporal Action Localization

International audienceCurrent state-of-the-art approaches for spatio-temporal action detection rely on detections at the frame level that are then linked or tracked across time. In this paper, we leverage the temporal continuity of videos instead of operating at the frame level. We propose the ACtion Tubelet detector (ACT-detector) that takes as input a sequence of frames and outputs tubelets, ie., sequences of bounding boxes with associated scores. The same way state-of-the-art object detectors rely on anchor boxes, our ACT-detector is based on anchor cuboids. We build upon the state-of-the-art SSD framework. Convolutional features are extracted for each frame, while scores and regressions are based on the temporal stacking of these features, thus exploiting information from a sequence. Our experimental results show that leveraging sequences of frames significantly improves detection performance over using individual frames. The gain of our tubelet detector can be explained by both more relevant scores and more precise localization. Our ACT-detector outperforms the state of the art methods for frame-mAP and video-mAP on the J-HMDB and UCF-101 datasets, in particular at high overlap thresholds

The Evolution of a Spatial Stochastic Network

The asymptotic behavior of a stochastic network represented by a birth and death processes of particles on a compact state space is analyzed. Births: Particles are created at rate $\lambda_+$ and their location is independent of the current configuration. Deaths are due to negative particles arriving at rate $\lambda_-$. The death of a particle occurs when a negative particle arrives in its neighborhood and kills it. Several killing schemes are considered. The arriving locations of positive and negative particles are assumed to have the same distribution. By using a combination of monotonicity properties and invariance relations it is shown that the configurations of particles converge in distribution for several models. The problems of uniqueness of invariant measures and of the existence of accumulation points for the limiting configurations are also investigated. It is shown for several natural models that if $\lambda_+<\lambda_-$ then the asymptotic configuration has a finite number of points with probability 1. Examples with $\lambda_+<\lambda_-$ and an infinite number of particles in the limit are also presented

Development of a personalized fall rate prediction model in community-dwelling older adults: a negative binomial regression modelling approach.

BACKGROUND Around a third of adults aged 65 and older fall every year, resulting in unintentional injuries in 30% of the cases. Fractures are a frequent consequence of falls, primarily caused in individuals with decreased bone strength who are unable to cushion their falls. Accordingly, an individual's number of experienced falls has a direct influence on fracture risk. The aim of this study was the development of a statistical model to predict future fall rates using personalized risk predictors. METHODS In the prospective cohort GERICO, several fall risk factor variables were collected in community-dwelling older adults at two time-points four years apart (T1 and T2). Participants were asked how many falls they experienced during 12 months prior to the examinations. Rate ratios for the number of reported falls at T2 were computed for age, sex, reported fall number at T1, physical performance tests, physical activity level, comorbidity and medication number with negative binomial regression models. RESULTS The analysis included 604 participants (male: 122, female: 482) with a median age of 67.90 years at T1. The mean number of falls per person was 1.04 and 0.70 at T1 and T2. The number of reported falls at T1 as a factor variable was the strongest risk factor with an unadjusted rate ratio [RR] of 2.60 for 3 falls (95% confidence interval [CI] 1.54 to 4.37), RR of 2.63 (95% CI 1.06 to 6.54) for 4 falls, and RR of 10.19 (95% CI 6.25 to 16.60) for 5 and more falls, when compared to 0 falls. The cross-validated prediction error was comparable for the global model including all candidate variables and the univariable model including prior fall numbers at T1 as the only predictor. CONCLUSION In the GERICO cohort, the prior fall number as single predictor information for a personalized fall rate is as good as when including further available fall risk factors. Specifically, individuals who have experienced three and more falls are expected to fall multiple times again. TRIAL REGISTRATION ISRCTN11865958, 13/07/2016, retrospectively registered

Nouvelles Topologies des diviseurs de puissance, balun et déphaseurs en bandes RF et millimétiques, apport des lignes à ondes lentes

L objectif de cette thèse a été premièrement de réaliser des dispositifs passifs intégrés à base de lignes à onde lentes nommées S-CPW (pour Slow-wave CoPlanar Waveguide ) aux fréquences millimétriques. Plusieurs technologies CMOS ou BiCMOS ont été utilisées: CMOS 65 nm et 28 nm ainsi que BiCMOS 55 nm. Deux baluns, le premier basé sur une topologie de rat-race et le second basé sur un diviseur de puissance de Wilkinson modifié, ainsi qu un inverseur de phase, ont été réalisés et mesurés dans la technologie CMOS 65 nm. Les résultats expérimentaux obtenus se situent à l état de l art en termes de performances électriques. Un coupler hybride et un diviseur de puissance avec des sorties en phase sans isolation ont été conçus en technologie CMOS 28 nm. Les simulations montrent de très bonnes performances pour des dispositifs compacts. Les circuits sont en cours de fabrication et pourront très bientôt être caractérisés. Ensuite, une nouvelle topologie de diviseurs de puissance, avec sorties en phase et isolé a été développée, offrant une grande flexibilité et compacité en comparaison des diviseurs de puissance traditionnels. Cette topologie est parfaitement adaptée pour les technologies silicium. Comme preuve de concept, deux diviseurs de puissance avec des caractéristiques différentes ont été réalisés en technologie PCB microruban à la fréquence de 2.45 GHz. Un composent a été conçu à 60 GHz en technologie BiCMOS 55 nm utilisant des lignes S CPW. Les simulations prouvent que le dispositif est faibles pertes, adapté et isolé. Les circuits sont également en cours de fabrication. Enfin, deux topologies de reflection type phase shifter ont été développées, la première dans la bande RF et la seconde aux fréquences millimétrique. Pour la bande RF, le déphasage atteint plus de 360 avec une figure de mérite très élevée en comparaison avec l état de l art. En ce qui concerne le déphaseur dans la bande millimétrique, la simulation montre un déphasage de 341 avec également une figure de mérite élevée.The first purpose of this work was the use of slow-wave coplanar waveguides (S CPW) to achieve various passive components with the aim to show their great potential and interest at millimetre-waves. Several CMOS or BiCMOS technologies were used: CMOS 65 nm and 28 nm, and BiCMOS 55 nm. Two baluns, one based on a rat-race topology and the other based on a modified Wilkinson power divider, and a phase inverter, were achieved and measured in a 65 nm CMOS technology. State-of-the-art results were achieved. A branch-line coupler and an in phase power divider without isolation were designed in a 28 nm CMOS technology. Really good performances are expected for these compact devices being yet under fabrication. Then, a new topology of in phase and isolated power divider was developed, leading to more flexibility and compactness, well suited to millimetre-wave frequencies. Two power dividers with different characteristics were realized in a PCB technology at 2.45 GHz by using microstrip lines, as a proof-of-concept. After that, a power divider was designed at the working frequency of 60 GHz in the 55 nm BiCMOS technology with S CPWs. The simulation results showed a low loss, full-matched and isolated component, which is also under fabrication and will be characterized as soon as possible. Finally, two new topologies of reflection type phase shifters were presented, one for the RF band and one for the millimetre-wave one. For the one in RF band, the phase shift can reach more than 360 with a great figure-of-merit as compared to the state-of-the-art. Concerning the phase shifter in the millimetre-wave band, the simulation results show a phase shift of 341 with also a high figure-of-merit.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Theoretical polarization dependence of the two-phonon double-resonant Raman spectra of graphene

The experimental Raman spectra of graphene exhibit a few intense two-phonon bands, which are enhanced through double-resonant scattering processes. Though there are many theoretical papers on this topic, none of them predicts the spectra within a single model. Here, we present results for the two-phonon Raman spectra of graphene calculated by means of the quantum perturbation theory. The electron and phonon dispersions, electronic lifetime, electron-photon and electron-phonon matrix elements, are all obtained within a density-functional-theory-based non-orthogonal tight-binding model. We study systematically the overtone and combination two-phonon Raman bands, and, in particular, the energy and polarization dependence of their Raman shift and intensity. We find that the ratio of the integrated intensities for parallel and cross polarized light for all two-phonon bands is between 0.33 and 0.42. Our results are in good agreement with the available experimental data