How to derive Feynman diagrams for finite-dimensional integrals directly from the BV formalism

The Batalin-Vilkovisky formalism in quantum field theory was originally invented to address the difficult problem of finding diagrammatic descriptions of oscillating integrals with degenerate critical points. But since then, BV algebras have become interesting objects of study in their own right, and mathematicians sometimes have good understanding of the homological aspects of the story without any access to the diagrammatics. In this note we reverse the usual direction of argument: we begin by asking for an explicit calculation of the homology of a BV algebra, and from it derive Wick's Theorem and the other Feynman rules for finite-dimensional integrals.Comment: 11 pages. Final versio

The effectiveness of thin films in lieu of hyperbolic metamaterials in the near field

We show that the near-field functionality of hyperbolic metamaterials (HMM), typically proposed for increasing the photonic local density of states (LDOS), can be achieved with thin metal films. Although HMMs have an infinite density of internally-propagating plane-wave states, the external coupling to nearby emitters is severely restricted. We show analytically that properly designed thin films, of thicknesses comparable to the metal size of a hyperbolic metamaterial, yield a LDOS as high as (if not higher than) that of HMMs. We illustrate these ideas by performing exact numerical computations of the LDOS of multilayer HMMs, along with their application to the problem of maximizing near-field heat transfer, to show that thin films are suitable replacements in both cases.Comment: 5 pages, 3 figure

Ted Hughes : speaking for the earth.

SIGLEAvailable from British Library Document Supply Centre- DSC:D98374 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Optimization of sharp and viewing-angle-independent structural color

Structural coloration produces some of the most brilliant colors in nature and has many applications. However, the two competing properties of narrow bandwidth and broad viewing angle have not been achieved simultaneously in previous studies. Here, we use numerical optimization to discover geometries where a sharp 7% bandwidth in scattering is achieved, yet the peak wavelength varies less than 1%, and the peak height and peak width vary less than 6% over broad viewing angles (0--90$^\circ$) under a directional illumination. Our model system consists of dipole scatterers arranged into several rings; interference among the scattered waves is optimized to yield the wavelength-selective and angle-insensitive response. Such designs can be useful for the recently proposed transparent displays that are based on wavelength-selective scattering

Medijsko zakonodavstvo i medijska politika u Slovačkoj: Ulazak u Europsku uniju i drugi val reformi

This article examines changes in Slovak media legislation during the accession period leading up to the joining of the European Union in May 2004. After providing a summary of the evolution of EU broadcasting policies, the authors first review the politicized nature of media development in Slovakia during the first decade of the post-communist experience, most importantly the private ownership of print media and a dual system of private and public broadcast media. The legacy of the restricted democracy that characterized the first five years of the independence of Slovakia was a commitment by the opposition at that time to civil society. The Council for Radio and Television Broadcasting, with EU guidance, prepared three laws, adopted by the Slovak parliament in 2000-01, which created the current legal media framework. Slovakia not only adopted the legislation required for EU accession, but at the same time it also advanced media regulation in other areas. The Slovak experience suggests the important role of consultation and consensus in designing media legislation. The evolution of new media technologies confronts both Slovakia and the EU with new challenges in regulation. The bases for all new Slovak policies are reflected in the National Policy for Electronic Communications, approved in 2003. The changes in Slovakia in media policy and administration related to EU accession should be seen as part of a larger process of media reorganization in Europe. They involve greater marketization, a two-tiered broadcasting systems and a changed definition of public broadcasting, trans-border ownership, globalization, and, more recently, a dramatic change in the technology and style of communication.Članak analizira promjene u slovačkom medijskom zakonodavstvu tijekom perioda pristupanja Slovačke članstvu u Europskoj uniji u svibnju 2004. Nakon sažetog prikaza razvoja politike emitiranja u Uniji, autori raspravljaju o ispolitiziranoj prirodi medijskog razvoja u Slovačkoj tijekom prvog desetljeća postkomunističkog iskustva, prije svega privatno vlasništvo tiskanih medija i dvojni sustav privatnih i javnih medija. Naslijeđe djelomične demokracije, koja je postojala prvih pet godina slovačke neovisnosti, bila je obveza opozicije prema tadašnjem civilnom društvu. Vijeće za radio i televiziju, pod vodstvom Unije, pripremilo je tri zakona koja je slovački parlament usvojio 2000. i 2001. godine, i koji predstavljaju trenutni medijski okvir. Slovačka ne samo da je usvojila zakone potrebne za pristup Uniji, nego je istodobno unaprijedila medijsku regulativu u drugim područjima. Slovačko iskustvo pokazuje važnost savjetovanja i konsenzusa u kreiranju medijskog zakonodavstva. Evolucija novih medijskih tehnologija suočava Slovačku i Europsku uniju s novim izazovima u regulaciji medija. Temelj svih budućih slovačkih medijskih politika vidljiv je u Nacionalnoj politici za elektronske komunikacije, koja je usvojena 2003. godine. Promjene u slovačkoj medijskoj politici i administraciji vezane uz Uniju dio su šireg procesa reorganizacije medija u Europi. One uključuju veću okrenutost tržištu, dualni sustav emitiranja, redefiniranje javnog emitiranja, prekogranično vlasništvo, globalizaciju, i odnedavna, dramatične promjene u tehnologiji i načinu komuniciranja