Differential Effect of Contrast Polarity Reversals in Closed Squares and Open L-Junctions

Scene segmentation depends on interaction between geometrical and photometric factors. It has been shown that reversals in contrast polarity at points of highest orientation discontinuity along closed contours significantly impair shape discrimination performance, while changes in contrast polarity at straight(er) contour segments do not have such deleterious effects (Spehar, 2002). Here we employ (semi) high resolution fMRI (1.5 mm × 1.5 mm × 1.5 mm) to investigate the neuronal substrate underlying these perception effects. Stimuli consisted of simple elements (a) squares with contrast reversals along straight segments; (b) squares with contrast reversals in the corner (highest orientation discontinuity); (c) L-Junctions with contrast reversals along the straight ends; (d) L-Junctions with contrast reversals in the corner. Element with contrast polarity reversals are easy to distinguish though appear geometrically equivalent. For squares with contrast polarity reversals only along straight lines we find significantly lower BOLD modulation compared to any of the control conditions, which show similar responses to each other. In the light of previous psychophysical work (Elder and Zucker, 1993; Spehar, 2002) we speculate that this effect is due to closure perception. We observe this across a wide range of areas on occipital cortex

The Influence of Computer Technologies on Contemporary Woven Fiber Art

It is generally agreed upon, by both the participants in the field and those few who have chronicled it, that the fiber art movement as we know it today began with Jean Lurcat in France in the late 1950s. He was among the first, if not the first, to make designs or cartoons specifically for the medium of tapestry. Previously, paintings were translated into the medium of tapestry. As well as creating the design or cartoon, he personally oversaw the actual weaving process. This direct connection between the process and the concept or image, the manual and the mind, laid the groundwork for the fiber arts of today. In 1962 Lurcat founded the Lausanne Tapestry Biennale, the international exhibition whose contents have profoundly influenced the course of this field. In fiber art, textiles are separated from function and, instead, focus on the maker\u27s expressive need. In this pursuit, historic techniques and constructions are used in new configurations. These processes offer the artist new methods of effecting visual and physical form, scale, and content. In the sixties, the results of these manipulations and interpretations were massive, excessive, and often three dimensional. In the late seventies and eighties, this unrestrained exuberance was modified. Concern was expended on the quality of the cloth as well as on the subtlety and specificity of the expressive content. More recently, the visual expressions of the portion of fiber artists who are weavers have been influenced by the possibilities inherent within computer technologies. The link between the computer and the loom is specific. They are both based on binary principles. It is said that the Jacquard loom was inspiration for the invention of the first computer. As Emily DuBois points out, Thousands of weave structures are derived from two simple positions of the warp—up and down. In the same way, the computer performs thousands of tasks based on two positions called 0 and 1. In weaving, these positions are notated on graph paper by a filled-in or black square when the warp is up and a white one when it is down. The 0\u27s and 1\u27s become the machine language of the computer

Effects of Rare-Gas Matrices on the Optical Response of Silver Nanoclusters

International audienceThe optical response of silver clusters, Agn with n = 8, 20, 35, 58, 92, embedded in a rare-gas matrix are calculated in the framework of the Time-Dependent Density Functional Theory (TDDFT). We present a methodology able to reproduce with unprecedented accuracy the experimental spectra measured on metal clusters embedded in neon, argon, krypton and xenon solid matrices. In our approach, the metal cluster is surrounded by explicit rare-gas atoms and embedded in a polarizable continuum medium. Interactions with the surrounding medium affects both the position and the width of the surface plasmon absorption band of metal clusters. The size dependent shift of the surface plasmon band is evaluated in the case of a neon matrix. While the band shifts to lower energies (red shift) for large clusters, it shifts to higher energies (blue shift) for very small clusters

Localized Surface Plasmon Resonance in Free Silver Nanoclusters Ag n , n = 20–147

International audienceAbsorption spectra of silver nanoclusters, Ag n with n = 20−147, are investigated in the framework of the time-dependent density functional theory (TDDFT) with the use of a range-separated hybrid density functional. Our calculated spectra reproduce well the experimental data. The plasmon-like band energy is situated at about 4 eV for all clusters in gas phase. A description of the plasmonic behavior is given using analyses and tools derived from ab initio quantum calculations. The plasmon band originates from multiple peaks gathered in a relatively small range of energy. High intensive peaks near the center of the band present a strong plasmonic character which has been characterized in terms of transition density, hole-electron excitation, transition contribution map (TCM), and generalized plasmonicity index (GPI)

Impact of DNA-Encoded Chemical Library Technology on Drug Discovery

DNA-Encoded Chemical Libraries (DELs) have gained momentum over the recent years for the discovery of small-molecule ligands and the technology has been integrated in most of the larger pharmaceutical companies. With this perspective we would like to summarize the development of DEL technology and present some representative DEL-derived hits which may soon enter the pharmaceutical market

Un Autre monde///dans notre monde : évocation contemporaine du réalisme fantastique

Dans le sillage du projet d’exposition collective itinérante toujours en mouvement depuis 2016, Un autre monde///dans notre monde est la première publication visant à rendre compte de cet événement multiple et en constante évolution. D’abord présentée à la galerie du jour agnès b. à Paris, puis à Bruxelles aux Halles Saint-Géry en 2018, à Marseille au Fond régional d’art contemporain en 2019 et enfin à Dunkerque en 2020, l’exposition, ainsi que l’ouvrage qui l’accompagne, porte sur le Réalism..

Robert et Delphine Milin : l’art les gens l’artiste

C’est à un regard personnel et intime que nous convie Robert Milin dans ce film tourné dans plusieurs régions de France, auprès d’amateurs et de participants au travail de l’artiste. Au fil des séquences, la dimension autobiographique du film est mise en évidence par le regard porté par la mère. En questionnant la valeur de l’œuvre d’art, son utilité et sa définition, c’est aussi et surtout la valeur du quotidien, du banal, du pratique et de l’ordinaire qu’interroge Robert Milin. On y découvr..

Vertigo: Op Art and a History of Deception, 1520 to 1970

Fruit de l’exposition itinérante Vertigo: Op Art and a History of Deception, 1520 to 1970, que l’on doit à la collaboration entre la conservatrice Eva Badura-Triska et l’artiste Markus Wörgötter, ce catalogue a bien de quoi confondre l’œil et le regard critique du lecteur. Question centrale des essais qui le composent, la notion de vertige est abordée selon un large panorama à la chronologie et aux angles d’approche étendus. Elle fait le lien entre les gravures de Piranèse et la scène de l’es..