Simulation of Metasurfaces in Finite Difference Techniques

We introduce a rigorous and simple method for analyzing metasurfaces, modeled as zero-thickness electromagnetic sheets, in Finite Difference (FD) techniques. The method consists in describing the spatial discontinuity induced by the metasurface as a virtual structure, located between nodal rows of the Yee grid, using a finite difference version of Generalized Sheet Transition Conditions (GSTCs). In contrast to previously reported approaches, the proposed method can handle sheets exhibiting both electric and magnetic discontinuities, and represents therefore a fundamental contribution in computational electromagnetics. It is presented here in the framework of the FD Frequency Domain (FDFD) method but also applies to the FD Time Domain (FDTD) scheme. The theory is supported by five illustrative examples

LE COMMENTAIRE D'AL-NAYRĪZĪ SUR LES DÉFINITIONS DU CINQUIÈME LIVRE DES ÉLÉMENTS

Ce document de travail contient la première traduction complète dans une langue moderne du commentaire d'al-Nayrizi sur les définitions du Livre V des Eléments d'Euclide; cette traduction se base directement sur les deux manuscrits existants.Al-Nayrizi (IXe-Xe siècles de notre ère) a écrit un commentaire sur les Eléments d'Euclide. Nous donnons ici une traduction française du passage de ce commentaire traitant des définitions du Livre V, où al-Nayrizi expose son point de vue sur la théorie des proportions entre grandeurs

Spacetime Processing Metasurfaces: GSTC Synthesis and Prospective Applications

The paper presents the general concept of spacetime processing metasurfaces, synthesized by generalized sheet transition conditions (GSTCs). It is shown that such metasurfaces can perform multiple simultaneous spatio-temporal processing transformations on incident electromagnetic waves. A time-reversal space-generalized-refraction metasurface and a multi-time-space-differentiating metasurfaces are presented as applications of the general spacetime processing metasurface concept

The Conditions of Subalternity: Reflections on Subjectivity, Experience and Hegemony

This paper uses Gayatri Spivak's discussion of Sati and Ranajit Guha's interpretive account of Chandra's death in colonial India in order to critically re-examine the concept of subalternity that runs through various postcolonial theories.  It is argued that there is a major tendency in postcolonial theory to conflate hegemony with domination.  By introducing the concept of experience, enabled by a reading of Antonio Gramsci's theory, the paper relates subalternity to hegemony and discusses that the success or failure of hegemony involves the degree to which hegemonic re-grounding can succeed in maintaining the existential continuum of the subject.

The Mulberry Tree, the Birds and the Divine in the Music of the Dotār in Khorāssān (Iran)

The relationship between music and environment plays an important role both in musical compositions and in research on music. The paper is about an anthropological study on the relationship between music of the long-necked lute dotār and the environment, in the region of Khorāssān in Iran. By examining the close relationship between the mulberry tree, birds, metaphor and music of dotār, we will try to show how the environmental factors, data or aspects can be directly or indirectly related to the music, particularly through the symbolism of Sufi beliefs in the region. These relationships to the nature are strongly linked to the perception and the discourse that a culture holds about its surrounding world

Effect of Oxidation-Reduction Potential on Hemochrome Formation and Resultant Pink Color Defect of Cooked Turkey Rolls

A pink color defect is commonly observed in freshly cut surfaces of cooked turkey rolls and fades rapidly upon exposure to air. The non uniform pink color makes the product appear undercooked, and the product must be discounted. The oxidation-reduction potential of the meat is important in development of pink defect. A pink color similar to that of commercial product was observed when the cooked meat was treated with either sodium nitrite or sodium dithionite. The pink color in nitrite treated meat was due to nitroso pigment formation, but in samples treated with dithionite the pink color was due to formation of a hemochrome complex. Pink color was also observed in turkey rolls formulated with nicotinic acid, nicotinamide or sodium nitrite. Reflectance and absorbance spectrophotometric studies on commercial or laboratory prepared samples having pink defect showed that the responsible pigment was a reduced hemochrome rather than a nitroso pigment. The hemochrome is probably a nicotinamide-denatured globin complex with ferrous iron of the heme molecule. Oxidation-reduction potential measurement of meat systems showed that hemochrome formation is promoted by reducing conditions and prevented by oxidizing conditions. All constituents necessary for formation of pink defect are present in turkey meat, the variable most affecting its appearance being the redox potential of the meat

LE COMMENTAIRE D'AL-MĀHĀNĪ SUR LE CONCEPT DE RAPPORT

Une traduction anglaise de ce texte a déjà été publiée en 2002 (voir Bijan Vahabzadeh (2002). Al-Mahani's Commentary on the Concept of Ratio. Arabic Sciences and Philosophy, 12, pp 9-52. doi:10.1017/S0957423902002023).Nous analysons ici le traité sur le rapport d'al-Māhānī (IXème siècle), l'un des premiers commentaires connus sur les concepts de rapport et de proportionnalité, et dans lequel il est question de la célèbre Définition V.5 des Eléments d'Euclide. On trouvera également en annexe une traduction française de ce traité