Unique intermetallic compounds prepared by shock wave synthesis

Technique compresses fine ground metallic powder mixture beyond crystal fusion point. Absence of vapor pressure voids and elimination of incongruous effects permit application of technique to large scale fabrication of intermetallic compounds with specific characteristics, e.g., semiconduction, superconduction, or magnetic properties

Unconventional Fusion and Braiding of Topological Defects in a Lattice Model

We demonstrate the semiclassical nature of symmetry twist defects that differ from quantum deconfined anyons in a true topological phase by examining non-abelian crystalline defects in an abelian lattice model. An underlying non-dynamical ungauged S3-symmetry labels the quasi-extensive defects by group elements and gives rise to order dependent fusion. A central subgroup of local Wilson observables distinguishes defect-anyon composites by species, which can mutate through abelian anyon tunneling by tuning local defect phase parameters. We compute a complete consistent set of primitive basis transformations, or F-symbols, and study braiding and exchange between commuting defects. This suggests a modified spin-statistics theorem for defects and non-modular group structures unitarily represented by the braiding S and exchange T matrices. Non-abelian braiding operations in a closed system represent the sphere braid group projectively by a non-trivial central extension that relates the underlying symmetry.Comment: 44 pages, 43 figure

Braiding Statistics and Congruent Invariance of Twist Defects in Bosonic Bilayer Fractional Quantum Hall States

We describe the braiding statistics of topological twist defects in abelian bosonic bilayer (mmn) fractional quantum Hall (FQH) states, which reduce to the Z_n toric code when m=0. Twist defects carry non-abelian fractional Majorana-like characteristics. We propose local statistical measurements that distinguish the fractional charge, or species, of a defect-quasiparticle composite. Degenerate ground states and basis transformations of a multi-defect system are characterized by a consistent set of fusion properties. Non-abelian unitary exchange operations are determined using half braids between defects, and projectively represent the sphere braid group in a closed system. Defect spin statistics are modified by equating exchange with 4\pi rotation. The braiding S matrix is identified with a Dehn twist (instead of a \pi/2 rotation) on a torus decorated with a non-trivial twofold branch cut, and represents the congruent subgroup \Gamma_0(2) of modular transformations.Comment: 6 pages, 3 figure

Trade liberalization and food security in Nepal

"Among South Asian countries, Nepal has liberalized most extensively during the 1980s and 1990s on both fronts, domestic and external. Nepal is a least developed country with a gross national product of US $235 per capita in 2001 and second lowest per capita wealth in the world. In South Asia, Nepal has the lowest per capita income, highest dependence of population on agriculture and second highest poverty rate. At the same time, on an average, Nepal has the lowest tariffs in South Asia and has taken several steps to downsize its public distribution system and remove a host of agricultural subsidies. This twin scenario where the lowest per capita income country is perhaps also the most liberalized makes for an interesting case for policy analysis. This paper reviews the outcomes from the liberalization policies followed by Nepal relating to food security." from Authors' Abstract

From orbifolding conformal field theories to gauging topological phases

Topological phases of matter in (2+1) dimensions are commonly equipped with global symmetries, such as electric-magnetic duality in gauge theories and bilayer symmetry in fractional quantum Hall states. Gauging these symmetries into local dynamical ones is one way of obtaining exotic phases from conventional systems. We study this using the bulk-boundary correspondence and applying the orbifold construction to the (1+1) dimensional edge described by a conformal field theory (CFT). Our procedure puts twisted boundary conditions into the partition function, and predicts the fusion, spin and braiding behavior of anyonic excitations after gauging. We demonstrate this for the electric-magnetic self-dual $\mathbb{Z}_N$ gauge theory, the twofold symmetric $SU(3)_1$, and the $S_3$-symmetric $SO(8)_1$ Wess-Zumino-Witten theories.Comment: 23 pages, 1 figur

Nonlinear Basis Pursuit

In compressive sensing, the basis pursuit algorithm aims to find the sparsest solution to an underdetermined linear equation system. In this paper, we generalize basis pursuit to finding the sparsest solution to higher order nonlinear systems of equations, called nonlinear basis pursuit. In contrast to the existing nonlinear compressive sensing methods, the new algorithm that solves the nonlinear basis pursuit problem is convex and not greedy. The novel algorithm enables the compressive sensing approach to be used for a broader range of applications where there are nonlinear relationships between the measurements and the unknowns