Face or building superiority in peripheral vision reversed by task requirements

Peripheral vision has been the topic of few studies compared with central vision. Nevertheless, given that visual information covers all the visual field and that relevant information can originate from highly eccentric positions, the understanding of peripheral vision abilities for object perception seems essential. The poorer resolution of peripheral vision would first suggest that objects requiring large-scale feature integration such as buildings would be better processed than objects requiring finer analysis such as faces. Nevertheless, task requirements also determine the information (coarse or fine) necessary for a given object to be processed. We therefore investigated how task and eccentricity modulate object processing in peripheral vision. Three experiments were carried out requiring finer or coarser information processing of faces and buildings presented in central and peripheral vision. Our results showed that buildings were better judged as identical or familiar in periphery whilst faces were better categorised. We conclude that this superiority for a given stimulus in peripheral vision results (a) from the available information, which depends on the decrease of resolution with eccentricity, and (b) from the useful information, which depends on both the task and the semantic category

Etude du Comportement des Ondes Ultrasonores dans l'Os Trabéculaire

National audienceLes techniques de mesures quantitatives par ultrasons sont non-destructives et à ce titre sont intéressantes pour déterminer les caractéristiques mécaniques et/ou géométriques de l'os in vivo ou in vitro. La mesure est basée sur l'estimation de vitesses et d'atténuations des ondes qui se sont propagées dans le tissu osseux. Cependant, l'interprétation des résultats est difficile du fait de la complexité de ce tissu lequel est élastique, poreux, anisotrope et hétérogène. Par exemple, en utilisant la technique de transmission transverse in vitro, des études théoriques et expérimentales ont montré que le comportement des ondes dans l'os spongieux, aussi appelé trabéculaire, dépend fortement de l'angle entre la direction d'émission des ondes et l'orientation des trabécules lesquelles constituent la microstructure de ce tissu. Les études réalisées in vitro sur l'os trabéculaire supposent que l'échantillon osseux est un matériau orthotrope dont les axes principaux sont définis par l'orientation des trabécules. Le comportement des ondes transmises à travers l'échantillon est différent selon que les signaux émis sont dans la direction (1) parallèle ou (2) perpendiculaire à la direction principale d'alignement des trabécules. En pratique, les échantillons d'os sont alors coupés suivant ces axes et les mesures sont réalisées pour chaque direction principale. Cependant, il est difficile en pratique de déterminer correctement ces axes et les directions d'émission des ondes peuvent ne pas être parfaitement alignées avec les axes principaux du matériau. Dans ce travail nous étudions les effets de ces erreurs d'alignement sur les caractéristiques des ondes. Pour cela, nous développons un modèle ainsi que son implémentation numérique à l'aide d'une méthode aux éléments finis pour étudier la propagation des ondes transitoires. Ce modèle constitue un système couplé d'un milieu poreux élastique anisotrope saturé (dont le comportement est décrit par le modèle de Biot) immergé dans un fluide acoustique

Investigations on (C6H9N2)2[MIIBr4] halogenometallate complexes with MII = Co, Cu and Zn: Crystal structure, thermal behavior and magnetic properties

International audienceThree complexes with the general formula (C6H9N2)2[MIIBr4] with MII = Cu (1), Co (2) and Zn (3) have been grown by the slow evaporation method at room temperature. These compounds were subjected to the following characterization techniques: single crystal X-ray diffraction, thermal analysis (ATG-TD), In situ X-ray powder diffraction and temperature dependent magnetic susceptibility measurements. The crystals of (C6H9N2)2[CuBr4] belong to the triclinic P1¯ space group, whereas (C6H9N2)2[CoBr4] and (C6H9N2)2[ZnBr4] crystallize in the orthorhombic system with the Pbcn space group. Molecular structures of the three coordination compounds consist of [MBr4]2- anions and 2-amino-6-methylpyridinium cations linked together via non-covalent interactions including hydrogen bonding, π···π stacking and halogen···halogen interactions which lead to three-dimensional supramolecular architecture. The thermal decomposition of the copper compound reveals the slow crystallization of CuBr at 130 °C. Both compounds 1 and 2 exhibit weak antiferromagnetic interactions. © 2017 Elsevier B.V

Zn2+ and Cu2+ doping of one-dimensional lead-free hybrid perovskite ABX3 for white light emission and green solar cell applications

International audienceThe one-dimensional ABX3 hybrid perovskite (A=(CH3)2NH2=DMA, B=Cd and X=Cl) was synthesized and structurally characterized. The optical analysis showed that the material has a direct band-gap nature with a gap energy of 5.36 eV. The obtained compound exhibited a “cold” white-light emission under an excitation wavelength of 240 nm with a color-rendering index up to 92 and a correlated color temperature (CCT) of 7582 K. The doping of the crystal with Cu2+ ions decreased the gap energy toward 2.51 eV. The partial substitution of the Cd atoms with Cu atoms decreased the intensity of the emitted white-light under 240 nm and led to a “cold” white-light emission with a CCT of 7117 K. The doping of the material with Zn2+ yielded a blue-shift and the emitted light revealed a CCT of 11,028 K. On the other hand, by incorporating Cu2+ions into the B site a broad absorption band is observed in the visible region resulting from the d-d transitions around the copper atoms which makes the material a good visible-light absorber. Hence, the Cu doped compound could be suitable for both white-light emission and photovoltaic solar cells

Antiviral Effects of Artemisinin and Its Derivatives against SARS-CoV-2 Main Protease: Computational Evidences and Interactions with ACE2 Allelic Variants

Fighting against the emergent coronavirus disease (COVID-19) remains a big challenge at the front of the world communities. Recent research has outlined the potential of various medicinal herbs to counteract the infection. This study aimed to evaluate the interaction of artemisinin, a sesquiterpene lactone extracted from the Artemisia genus, and its derivatives with the SARS-CoV-2 main protease. To assess their potential use against COVID-19, the interactions of the main active principle of Artemisia with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) was investigated through in silico probing. Our results showed that artemesinin and its derivatives manifested good oral absorption and bioavailability scores (0.55). They potently bound to the Mpro site of action—specifically, to its Cys145 residue. The selected compounds established two to three conventional hydrogen bonds with binding affinities ranging between −5.2 and −8.1 kcal/mol. Furthermore, artemisinin interactions with angiotensin converting enzyme 2 (ACE2) were dependent on the ACE2 allelic variants. The best score was recorded with rs961360700. A molecular dynamic simulation showed sufficient stability of the artemisinin–Mpro complex on the trajectory of 100 ns simulation frame. These binding interactions, together with drug-likeness and pharmacokinetic findings, confirmed that artemisinin might inhibit Mpro activity and explain the ethnopharmacological use of the herb and its possible antiviral activity against SARS-CoV-2 infection inducing COVID-19. Nevertheless, it interacted differently with the various ACE2 allelic variants reported to bind with the SARS-CoV-2 spike protein