Acoustic metafluids made from three acoustic fluids

Significant reduction in target strength and radiation signature can be achieved by surrounding an object with multiple concentric layers comprised of three acoustic fluids. The idea is to make a finely layered shell with the thickness of each layer defined by a unique transformation rule. The shell has the effect of steering incident acoustic energy around the structure, and conversely, reducing the radiation strength. The overall effectiveness and the precise form of the layering depends upon the densities and compressibilities of the three fluids. Nearly optimal results are obtained if one fluid has density equal to the background fluid, while the other two densities are much greater and much less than the background values. Optimal choices for the compressibilities are also found. Simulations in 2D and 3D illustrate effectiveness of the three fluid shell. The limited range of acoustic metafluids that are possible using only two fluid constituents is also discussed.Comment: 12 pages, 11 figure

Francoprovençal: Documenting contact varieties in Europe and North America

This special issue of the International Journal of the Sociology of Language brings together articles from an international set of authors that situate the family of Francoprovençal (FP) dialects in terms of formal structures, contexts of contact, practice and policy. FP has been the subject of little scholarly attention. This dearth of research is largely the result of its ambiguous status. Ever since it was introduced by Ascoli (1878 [1874]), the notion of FP has been questioned. There has long been disagreement over its linguistic borders and the linguistic criteria used for demarcation. As late as 2007, scholars have asked: le francoprovençal existe-t-il ? [does FP exist?] (Tuaillon 2007: 9). This is the first collection describing FP across its entire geographical distribution and assembling varied sociolinguistic approaches. Previous collections include a dialectology volume focusing on the status and structure of FP (Marzys (1971); a posthumous volume focusing on Lyonnais (Gardette 1983); and Fréchet (2009), consisting of descriptions of both FP and Occitan. These works – though important contributions to FP linguistics – provide little quantitative substance. Moreover, little work on FP has been produced in English, which limits access to researchers worldwide who might be interested in the sociolinguistic context of FP or comparison with other minority-language contexts. To begin to fill this void, we introduce FP, then outline the key themes of this issue and the range of sociolinguistic traditions covered

Spontaneous Breaking of Chiral Symmetry as a Consequence of Confinement

We show that at the leading order in the large-$N$ expansion a lattice QCD motivated linear rising confinement potential at large distances leads to a non-local four-quark interaction that realizes spontaneous breaking of chiral symmetry (SBCS) in the same way the Nambu-Jona-Lasinio model does. The dynamical quark mass $m$, which represents the solution of the gap-equation, is proportional to the square root of the string tension $\sigma$ and takes the form at the leading order in the large-$N$ expansion $m=2 \sqrt{\sigma}/\pi$ with $\sigma=0.27$ GeV$^2$. The Nambu-Jona-Lasinio phenomenological constant $G_1$, which is responsible for SBCS, is expressed in terms of the string tension and the confinement radius.Comment: 10 pages, 0 figures, latex, IK-TUW-Preprint 930540

Investigation of the composition of the Luna 16 lunar sample

The concentrations of aluminum, manganese, sodium, chromium, iron, cobalt, and 12 rare earth elements were determined by neutron activation analysis using slow neutrons. Oxygen and silicon were determined using a fast neutron generator. Mossbauer spectroscopy was used to investigate iron compounds in Luna 16 regolith samples from the upper part of the core

Ordering variable for parton showers

The parton splittings in a parton shower are ordered according to an ordering variable, for example the transverse momentum of the daughter partons relative to the direction of the mother, the virtuality of the splitting, or the angle between the daughter partons. We analyze the choice of the ordering variable and conclude that one particular choice has the advantage of factoring softer splittings from harder splittings graph by graph in a physical gauge.Comment: 28 pages, 5 figure