Conservatoire national des arts et métiers

About: Conservatoire national des arts et métiers is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 3573 authors who have published 7127 publications receiving 141430 citations. The organization is also known as: CNAM & Conservatoire des arts et métiers.

Minimum d-blockers and d-transversals in graphs

Abstract: We consider a set V of elements and an optimization problem on V: the search for a maximum (or minimum) cardinality subset of V verifying a given property ?. A d-transversal is a subset of V which intersects any optimum solution in at least d elements while a d-blocker is a subset of V whose removal deteriorates the value of an optimum solution by at least d. We present some general characteristics of these problems, we review some situations which have been studied (matchings, s---t paths and s---t cuts in graphs) and we study d-transversals and d-blockers of stable sets or vertex covers in bipartite and in split graphs.

End-to-End Learning of Latent Deformable Part-Based Representations for Object Detection

Abstract: Object detection methods usually represent objects through rectangular bounding boxes from which they extract features, regardless of their actual shapes. In this paper, we apply deformations to regions in order to learn representations better fitted to objects. We introduce DP-FCN, a deep model implementing this idea by learning to align parts to discriminative elements of objects in a latent way, i.e. without part annotation. This approach has two main assets: it builds invariance to local transformations, thus improving recognition, and brings geometric information to describe objects more finely, leading to a more accurate localization. We further develop both features in a new model named DP-FCN2.0 by explicitly learning interactions between parts. Alignment is done with an in-network joint optimization of all parts based on a CRF with custom potentials, and deformations are influencing localization through a bilinear product. We validate our models on PASCAL VOC and MS COCO datasets and show significant gains. DP-FCN2.0 achieves state-of-the-art results of 83.3 and 81.2% on VOC 2007 and 2012 with VOC data only.

PAPR-Aware Massive MIMO-OFDM Downlink

Abstract: We investigate the peak-to-average power ratio (PAPR) reduction problem in orthogonal frequency-division multiplexing-based massive multi-user (MU) multiple-input multiple-output (MIMO) downlink systems. In this paper, we develop a downlink transmission scheme that performs jointly MU precoding and PAPR reduction (PP) by exploiting the excess degrees of freedom offered by equipping the BS by a large number of antennas. Specifically, the joint MU precoding and PAPR reduction scheme is formulated as a simple convex optimization problem solved via steepest gradient descent (GD) approach. Then, we develop a novel algorithm, referred to as MU-PP-GDm, to reduce the PAPR of the transmitted signals by exploiting the high-dimensional null space of the MIMO channel matrix while maintaining an excellent transmission quality. The simulation results show that the proposed MU-PP-GDm has low computational complexity and can achieve substantial PAPR performance with a fast convergence rate.

Dehydroepiandrosterone 7α‐ and 7β‐Hydroxylation in Mouse Brain Microsomes. Effects of Cytochrome P450 Inhibitors and Structure‐Specific Inhibition by Steroid Hormones

Abstract: Presently, several works question the effects of dehydroepiandrosterone (DHEA) reported in vivo and designate its 7-hydroxylated metabolites as native antiglucocorticoids and potent mediators in the triggering of immune response. Among mouse tissues and organs, and second to liver, the largest production of 7alpha-and 7beta-hydroxylated derivatives of DHEA takes place in brain microsomes. To contribute to identification of cytochromes P450 (CYPs) responsible for 7alpha- and 7beta-hydroxy-DHEA production, effects of CYP inhibitors and of several steroid hormones on DHEA 7-hydroxylation were examined. Using mouse brain microsomes as a source of enzyme, we report now that strong and smaller inhibitions of DHEA 7alpha-hydroxylation were obtained with ketoconazole and alpha-naphthoflavone, respectively, and that neither changed DHEA 7beta-hydroxylation. Metyrapone and antipyrine also inhibited 7alpha-hydroxylation, but by contrast, significantly increased 7beta-hydroxylation of DHEA. This indicated that at least, two different CYPs were responsible for 7alpha- and 7beta-hydroxylation of DHEA. Steroids sharing a 3beta-hydroxylated structure with DHEA, namely pregnenolone, 5-androstene-3beta,17beta-diol and 3beta-hydroxy-5alpha-androstan-17-one, were strong inhibitors of DHEA 7alpha-hydroxylation (non-competitive inhibition with pregnenolone, Ki=2.0 +/- 0.3 microM). In contrast, 7beta-hydroxylation yields were not decreased by the 3beta-hydroxysteroids tested. Moderate inhibition of 7alpha- and 7beta-hydroxylation was obtained with 3-oxosteroids, namely testosterone, progesterone, corticosterone and 4-androsten-3,17-dione. Taken together, these data indicate specific inhibition patterns of DHEA 7alpha- and 7beta-hydroxylation by CYP inhibitors and steroid hormones in mouse brain microsomes and may be used as criteria necessary for identification of the responsible CYP species.