Science & Mathematics

The SoftCast video transmission scheme has been proposed as a promising alternative to traditional video broadcasting systems in wireless error-prone environments. However, in its original form, the scheme may introduce annoying artifacts such as temporal quality variations or the so-called ghost effect. To eliminate this artifact as well as improving the received quality, we recently proposed an updated version of SoftCast: Adaptive GoP-size mechanism based on Content and Cut detection for SoftCast (AGCC-SoftCast) [1]. In this paper, we provide additional results and verify the validity of the algorithm considering different video content and resolution. We also analyze the behaviors of the scheme considering different type of cuts: 1) Abrupt cuts i.e., a cut that appear between two different scenes, 2) Soft cuts that may appear in a same scene and 3) Intraframe cuts that represents a shot change inside a limited portion of the frame. The performance of AGCC-SoftCast are compared to the original SoftCast scheme under different Channel Signal-to-Noise Ratios (CSNR) and Compression Ratios (CR). Traditional objective metrics are considered such as: the Peak Signal-to-Noise Ratio (PSNR), the Structural SIMilarity (SSIM) and the Multi-Scale SSIM (MS-SSIM). In addition, the recent Video Multi-method Assessment Fusion (VMAF) metric proposed by Netflix is also used. Regardless of the CSNR and CR values, results clearly highlight the importance of the AGCC algorithm in a SoftCast wireless video transmission scheme. Depending on the transmitted video content, results show that improvements up to 11.6dB in terms of PSNR and 67.45 in terms of VMAF can be obtained, especially at the cut boundaries.

La structuration à l’échelle submicronique de la surface des aciers inoxydables permet de leur apporter de nouvelles fonctionnalités, par exemple pour des applications tribologiques et optiques. Cette thèse s’inscrit dans le cadre du projet ANR SPOT qui a pour objectif de structurer à l’échelle submicronique la surface d’aciers austénitiques et martensitiques par gravure sèche. Dans ce travail, nous avons développé un procédé plasma avec un mélange de chlore et d’argon pour la gravure des aciers inoxydables. La mise au point de ce procédé a été réalisée en se basant sur l’étude de la gravure des métaux principaux qui composent ces aciers, à savoir, le fer, le chrome et le nickel. En se basant sur des mesures de vitesses de gravure, ainsi que sur des techniques de diagnostics plasmas, nous avons montré que, dans un plasma de chlore et d’argon, le fer est l’élément qui se grave le plus, suivi du chrome puis du nickel. Les échantillons métalliques ainsi que les aciers inoxydables gravés ont été analysés par des techniques de caractérisation de surface notamment des analyses de spectrométrie photoélectronique X (XPS). Nous avons également étudié la variation des vitesses de gravures de ces métaux et de ces aciers en fonction de la température des substrats. Ces études nous ont permis d’établir les mécanismes mis en jeu en cours de la gravure des éléments métalliques. Nous avons montré que, dans un plasma de chlore et d’argon, le fer se grave principalement par un mécanisme chimique qui suit une loi d’Arrhenius. Ce mécanisme serait basé sur la formation de chlorures de fer volatiles. Dans le cas du chrome, la gravure nécessite une assistance ionique afin de désorber les chlorures de chrome non volatiles formés à la surface du matériau. Enfin, pour le nickel, nous avons observé que la vitesse de gravure diminue lorsque la température augmente. Dans ce cas, des observations au microscope électronique à balayage ont permis de mettre en évidence la formation de gonflements riches en chlore. Les analyses XPS de la surface gravée du nickel suggère que ces gonflements sont dus à la formation de chlorures de nickel non volatiles. Ces chlorures seraient à l’origine de la diminution de la vitesse de gravure du nickel dont la pulvérisation se trouverait bloquée par la présence de ces chlorures. La compréhension de ces mécanismes a permis de conclure que, dans un plasma chloré, l’élément bloquant dans la gravure des aciers inoxydables est le nickel.

The aim of this work is to characterize olive oils from six algerian cultivars (Azeradj, n=4); Blanquette, n=7; Bouricha, n=2; Chemlal, n=5; Limli, n=3; Sigoise, n=1) by determining their fatty acid compositions. The fatty acid composition of oils is determined using gas chromatography of methyl esters obtained by transesterification of triacylglycerols with 2M KOH/MeOH. Fourteen fatty acids and squalene are identified in all the samples. Oleic acid (18:1ω9), palmitic acid (16:0), linoleic acid (18:2ω6) and stearic acid (18:0) are the major fatty acids commonly found in olive oils. Palmitoleic acid (16:1ω7), hypogeic acid (16:1ω9), oleic acid (18:1ω9) and cis-vaccenic acid (18:1ω7) are considered as separate entities by the European regulation, unlike the Codex Alimentarius which identifies them as a single component. Six minor fatty acids namely margaric acid (17:0), margaroleic acid (17:1ω8), arachidic acid (20:0), gondoïque acid (20:1ω9), behenic acid (22:0) and lignoceric acid (24:0) are identified. These acids, although minor, are important for the characterization of cultivars. Oils of different cultivars are characterized by different fatty acid compositions. All the values of fatty acid compositions are in compliance with the regulations of the International Olive Oil Council and Codex Alimenta-rius. A radial plot enables the analysis and characterization of each variety as a " morphotype " by creating a " morphogramme ". The " morphogramme " is designed as a radial representation of each fatty acid (n=14) using an Excel ® spreadsheet, and each axis represents the change in the variable with respect to the mean. The " morphotypes " are real fingerprints of different oil cultivars. Thus, the oils of Azeradj, Blanquette, Chemlal, Limli and Sigoise cultivars have specific " morphotype ". The " morphotype " of the Bourricha cultivar is very similar to the Chemlal cultivar. In addition, the Blanquette " morphotype " is identical to that of the tunisian cultivar Chetoui. This mode of representation is particularly effective for the rapid visual identification of characteristics of olive oils.

Among the different chemotherapies available, genotoxic drugs are widely used. In response to these drugs, particularly doxorubicin, tumor cells can enter into senescence. Chemotherapy‑induced senescence (CIS) is a complex response. Long described as a definitive arrest of cell proliferation, the present authors and various groups have shown that this state may not be complete and could allow certain cells to reproliferate. The mechanism could be due to the activation of new signaling pathways. In the laboratory, the proteins involved in these pathways and triggering cell proliferation were studied. The present study determined a new role for anterior gradient protein 2 (AGR2) in vivo in patients and in vitro in a senescence escape model. AGR2's implication in breast cancer patients and proliferation of senescent cells was assessed based on a SWATH‑MS proteomic study of patients' samples and RNA interference technology on cell lines. First, AGR2 was identified and it was found that its concentration is higher in the serum of patients with breast cancer and that this high concentration is associated with metastasis occurrence. An inverse correlation between intratumoral AGR2 expression and the senescence marker p16 was also observed. This observation led to the study of the role of AGR2 in the CIS escape model. In this model, it was found that AGR2 is overexpressed in cells during senescence escape and that its loss considerably reduces this phenomenon. Furthermore, it was shown that the extracellular form of AGR2 stimulated the reproliferation of senescent cells. The power of proteomic analysis based on the SWATH‑MS approach allowed the present study to highlight the mammalian target of rapamycin (mTOR)/AKT signaling pathway in the senescence escape mechanism mediated by AGR2. Analysis of the two signaling pathways revealed that AGR2 modulated RICTOR and AKT phosphorylation. All these results showed that AGR2 expression in sera and tumors of breast cancer patients is a marker of tumor progression and metastasis occurrence. They also showed that its overexpression regulates CIS escape via activation of the mTOR/AKT signaling pathway.

The pyroelectric, dielectric properties and shear moduli Gx, Gy and Gz as well as the internal friction Q -1 of NaKSO4 crystals were studied in the temperature range from 100 up to 300 K. An inverted torsion pendulum technique was used to determine the temperature dependence of both shear moduli and internal friction. The results of the pyroelectric measurements are in agreement with the centrosymmetric class of NaKSO 4. The variation of the dielectric constants with temperature shows two segments with different slopes. Anisotropic behaviour in the temperature dependence of the shear moduli was also observed. The internal friction showed a pronounced maximum in the z-direction at 200 K.

Polycrystalline of [(Na0.535K0.480)0.966Li0.058](Nb0.90Ta0.10)O3 samples were prepared using the high-temperature solid-state reaction technique. X-ray diffraction (XRD) analysis indicates the formation of a single-phase with orthorhombic structure. AC impedance plots were used as tool to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The AC impedance studies revealed the presence of grain effect, from 425°C onwards. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) characteristic of NKLNT. The AC conductivity results were used to correlate with the barrier hopping (CBH) model to evaluate the binding energy (Wm), the minimum hopping distance (Rmin), the density of states at Fermi level (N(Ef)), and the activation energy of the compound.

Usually, identification models of parallel robots are simplified and take only the dynamics of the moving platform into account. Moreover the input efforts are estimated through the use of the manfucaturer's actuator drive gains that are not calibrated thus leading to identification errors. In this paper a systematic way to derive the full dynamic identification model of the Orthoglide parallel robot in combination with a method that allows the identification of both robot inertial parameters and drive gains.

This work puts forth a probabilistic graphical framework to track unoccluded objects undergoing large out of image plane rotations and/or presenting large scale variations in video sequences. The proposed scheme incorporates measurements from an ensemble of local patch trackers and inter-patch geometric layout to arrive at a sample based approximation of the state posterior. Following this, the geometric layout is updated online using the Iterative Conditional Estimation technique. These steps are iterated until convergence to arrive at the final state posterior. In contrast to offline training based schemes the proposed framework imposes no prior on the geometric layout and instead relies on online update of the geometric layout, thus broadening the scope of usage. Amongst other advantages, the scheme implicitly estimates the scale of the target and also adapts to varying target appearances to enable tracking under a fair degree of out of the image plane rotations. The tracking abilities of this scheme is put to test on several challenging videos with scale changes, out of the image plane rotations, illumination changes and motion jerks. Whereever possible qualitative comparisons are facilitated using videos from standard databases.

La théorie de l'évaluation d'impact est richement fournie dans la littérature ainsi que les méthodes économétriques qui s'y rapportent. Toutes ces méthodes cherchent à estimer le contre-factuel. Depuis la version 13 de stata, il existe des commandes offcielles qui permettent d'appliquer les méthodes d'évaluation d'impact et de s'affranchir des commandes des utilisateurs qui, pour la plus part, fond intervenir plusieurs étapes en plus de l'installation des ados. Dans cet article, les nouvelles méthodes présentement disponibles sur stata (version 18, 2021) sont mises en eouvre

Amérique latine - Political Outlook est une publication de l’Observatoire politique de l’Amérique latine et des Caraïbes (Opalc) du CERI-Sciences Po. Il prolonge la démarche du site www.sciencespo.fr/opalc en offrant des clés de compréhension d’un continent en proie à des transformations profondes.

Vehicle mass plays an influential role in various dynamical systems for vehicle safety and control. In this work, a novel recursive total least squares (RTLS) solution is presented for the online estimation of gross vehicle mass. The proposed method requires access to engine torque, engine speed, wheel speed, and vehicle IMU acceleration measurements. Different algorithm configurations are considered for mass estimation of internal combustion engine and electric vehicles, with a focused application to passenger cars and light commercial vehicles. The baseline RTLS algorithm is improved by means of regularization, outlier attenuation, parameter projection, and enhanced tracking of jumping parameters, all of which play an important role in optimizing estimator performance for industrial applications. The proposed algorithm is then generalized to account for heterogeneous and heteroscedastic measurement noise with a recursive noise covariance estimation algorithm. The method is tested against two well-known benchmark algorithms from the mass estimation literature with experimental electric vehicle data, and solution sensitivity to model assumptions and model input parameters is discussed. The vehicle experiments show that the proposed method outperforms the benchmark methods in terms of accuracy and convergence characteristics.

Infrared imaging finds numerous applications in airborne measurements, structural monitoring, medical diagnostics, and spectroscopy. Long wave infrared (LWIR) radiation (λ = 8-14 µm) enables self-illuminated thermal imaging, and can uniquely identify different chemical species. The investigation of thermal emission control using plasmonic antenna devices, 1 and the study of tunable free-form planar optics 2 has motivated our development of a novel high-resolution thermal imaging technique. Speckle imaging has been successfully used to image optical intensity or phase through complex inhomogeneous scattering media-particularly at visible wavelengths, 3 and recently in the infrared. 4 Single-shot high-resolution images of the scattered light capture sufficient information to reconstruct images through opaque media and around corners with diffraction-limited resolution. In this context, we have developed a high-resolution broadband speckle imaging setup in the LWIR for phase reconstruction, using a thin scattering medium in front of an uncooled microbolometric camera. Our method utilizes the large angular memory effect of a thin scattering medium. Local phase gradients within the incoming beam produce distorted speckle images after scattering by the scatterer's surface. Local translation shifts between the speckle patterns are estimated by a fast diffeomorphic image registration algorithm to obtain a phase gradient map. Integrating this gradient map in 2-D finally yields the wavefront profile. We demonstrate infrared phase image reconstruction using our broadband LWIR speckle imaging methodology, which promises future applications in imaging through visually opaque objects like semiconductor circuits, solid-state nanoelectronics, and infrared optical components, for defect monitoring.

As digital data transmission continues to scale, concerns about privacy grow increasingly urgent -yet privacy remains a socially constructed and ambiguously defined concept, lacking a universally accepted quantitative measure. This work examines information leakage in image data, a domain where information-theoretic guarantees are still underexplored. At the intersection of deep learning, information theory, and cryptography, we investigate the use of mutual information (MI) estimators -in particular, the empirical estimator and the MINE framework -to detect leakage from selectively encrypted images. Motivated by the intuition that a robust estimator would require a probabilistic frameworks that can capture spatial dependencies and residual structures -even within encrypted representations -our work represent a promising direction for image information leakage estimation.

Ce travail porte sur la conception de nouveaux systèmes luminescents à partir de complexes hexanucléaires de terres rares et l'étude de leurs propriétés physico-chimiques. Ces complexes de formule chimique [Ln6(μ6-O)(μ3-OH)8(NO3)6(H2O)n](NO3)2.mH2O avec 0 n 14 et 0 m 6 pour Ln = Pr-Lu, Y peuvent être synthétisés et isolés par hydrolyse contrôlée de sels de terres rares. Ces complexes sont structuralement caractérisés : les ions terres rares occupent les sommets d'un octaèdre moléculaire d'une dizaine d'angströms de diamètre. Ils présentent un intérêt en tant que précurseurs moléculaires. Les complexes hétéro-hexanucléaires, associant plusieurs terres rares, affichent potentiellement des interactions de forte amplitude en termes de luminescence. L’ordre local de ces complexes a été étudié notamment par RMN du noyau 89Y à l’état solide et en solution. Ces complexes ne montrent pas de ségrégation macroscopique, et sont des solutions solides où les terres rares sont statiquement et aléatoirement réparties sur les sommets de chaque entité moléculaire. Ces interactions ont été exploitées afin d’optimiser les propriétés inédites de luminescence d’un polymère de coordination à base d’entités hexanucléaires. Ces propriétés sont modulables en fonction de la sélection des précurseurs. Ces complexes présentent une affinité particulière pour les solvants de type polyol, notamment l’éthylène glycol. En solution, les entités moléculaires se regroupent par le biais de ponts glycol et forment des nano-agrégats. Enfin, cette affinité particulière pour les polyols, nous a poussé à étudier les propriétés de luminescence en solution lorsque les complexes sont fonctionnalisés par des dérivés aromatiques du glycol.