Homology and K-theory of the Bianchi groups

We reveal a correspondence between the homological torsion of the Bianchi groups and new geometric invariants, which are effectively computable thanks to their action on hyperbolic space. We use it to explicitly compute their integral group homology and equivariant $K$-homology. By the Baum/Connes conjecture, which holds for the Bianchi groups, we obtain the $K$-theory of their reduced $C^*$-algebras in terms of isomorphic images of the computed $K$-homology. We further find an application to Chen/Ruan orbifold cohomology. % {\it To cite this article: Alexander D. Rahm, C. R. Acad. Sci. Paris, Ser. I +++ (2011).

Weighted Estimates for the Berezin Transform and Bergman Projection on the Unit Ball in Cn\mathbb{C}^{n}

Using modern techniques of dyadic harmonic analysis, we are able to prove sharp estimates for the Bergman projection and Berezin transform and more general operators in weighted Bergman spaces on the unit ball in $\mathbb{C}^n$. The estimates are in terms of the Bekolle-Bonami constant of the weight.Comment: v1 19 page

Influence of point defects on magnetic vortex structures

We employed micro-Hall magnetometry and micromagnetic simulations to investigate magnetic vortex pinning at single point defects in individual submicron-sized permalloy disks. Small ferromagnetic particles containing artificial point defects can be fabricated by using an image reversal electron beam lithography process. Corresponding micromagnetic calculations, modeling the defects within the disks as holes, give reasonable agreement between experimental and simulated pinning and depinning field values

MARKET FORCES AND CHANGES IN THE PLANT INPUT SUPPLY INDUSTRY

Agribusiness, Input Supply Industry, Fertilizer, Plant Nutrients, Seed, Capital, Market Forces, Structural Change, Porter’s Five Forces, Agribusiness, Q13, L10, L22, M22, L80,

Construction of invisibility cloaks of arbitrary shape and size using planar layers of metamaterials

Transformation optics (TO) is a powerful tool for the design of electromagnetic and optical devices with novel functionality derived from the unusual properties of the transformation media. In general, the fabrication of TO media is challenging, requiring spatially varying material properties with both anisotropic electric and magnetic responses. Though metamaterials have been proposed as a path for achieving such complex media, the required properties arising from the most general transformations remain elusive, and cannot implemented by state-of-the-art fabrication techniques. Here, we propose faceted approximations of TO media of arbitrary shape in which the volume of the TO device is divided into flat metamaterial layers. These layers can be readily implemented by standard fabrication and stacking techniques. We illustrate our approximation approach for the specific example of a two-dimensional, omnidirectional "invisibility cloak", and quantify its performance using the total scattering cross section as a practical figure of merit. © 2012 American Institute of Physics.U.S. Army Research Office (Contract No. W911NF-09-1-0539)

VirtualEMF: a Model Virtualization Tool

International audienceSpecification of complex systems involves several heterogeneous and interrelated models. Model composition is a crucial (and complex) modeling activity that allows combining different system perspectives into a single cross-domain view. Current composition solutions fail to fully address the problem, presenting important limitations concerning efficiency, interoperability, and/or synchronization. To cope with these issues, in this demo we introduce VirtualEMF: a model composition tool based on the concept of a virtual model, i.e., a model that do not hold concrete data, but that redirects all its model manipulation operations to the set of base models from which it was generated

Transformation Optics for Plasmonics

A new strategy to control the flow of surface plasmon polaritons at metallic surfaces is presented. It is based on the application of the concept of Transformation Optics to devise the optical parameters of the dielectric medium placed on top of the metal surface. We describe the general methodology for the design of Transformation-Optical devices for surface plasmons and analyze, for proof-of-principle purposes, three representative examples with different functionalities: a beam shifter, a cylindrical cloak and a ground-plane cloak.Comment: 15 pages, 3 figure