Vertex Operators in 4D Quantum Gravity Formulated as CFT

We study vertex operators in 4D conformal field theory derived from quantized gravity, whose dynamics is governed by the Wess-Zumino action by Riegert and the Weyl action. Conformal symmetry is equal to diffeomorphism symmetry in the ultraviolet limit, which mixes positive-metric and negative-metric modes of the gravitational field and thus these modes cannot be treated separately in physical operators. In this paper, we construct gravitational vertex operators such as the Ricci scalar, defined as space-time volume integrals of them are invariant under conformal transformations. Short distance singularities of these operator products are computed and it is shown that their coefficients have physically correct sign. Furthermore, we show that conformal algebra holds even in the system perturbed by the cosmological constant vertex operator as in the case of the Liouville theory shown by Curtright and Thorn.Comment: 26 pages, rewrote review part concisely, added explanation

Making a Universe

For understanding the origin of anisotropies in the cosmic microwave background, rules to construct a quantized universe is proposed based on the dynamical triangulation method of the simplicial quantum gravity. A $d$-dimensional universe having the topology $D^d$ is created numerically in terms of a simplicial manifold with $d$-simplices as the building blocks. The space coordinates of a universe are identified on the boundary surface $S^{d-1}$, and the time coordinate is defined along the direction perpendicular to $S^{d-1}$. Numerical simulations are made mainly for 2-dimensional universes, and analyzed to examine appropriateness of the construction rules by comparing to analytic results of the matrix model and the Liouville theory. Furthermore, a simulation in 4-dimension is made, and the result suggests an ability to analyze the observations on anisotropies by comparing to the scalar curvature correlation of a $S^2$-surface formed as the last scattering surface in the $S^3$ universe.Comment: 27pages,18figures,using jpsj.st

Role of covalency in the ground state properties of perovskite ruthenates: A first principle study using local spin density approximations

We investigate the electronic structure of SrRuO3 and CaRuO3 using full potential linearized augmented plane wave method within the local spin density approximations. The ferromagnetic ground state in SrRuO3 could exactly be described in these calculations and the calculated spin magnetic moment is found to be close to the experimentally observed values. Interestingly, the spin polarized calculations for CaRuO3 exhibit large spin moment as observed in the experiments but the magnetic ground state has higher energy than that in the non-magnetic solution. Various calculations for different structural configurations indicate that Ca-O covalency plays the key role in determining the electronic structure and thereby the magnetic ground state in this system.Comment: 8 figure

Recursion Relations in Liouville Gravity coupled to Ising Model satisfying Fusion Rules

The recursion relations of 2D quantum gravity coupled to the Ising model discussed by the author previously are reexamined. We study the case in which the matter sector satisfies the fusion rules and only the primary operators inside the Kac table contribute. The theory involves unregularized divergences in some of correlators. We obtain the recursion relations which form a closed set among well-defined correlators on sphere, but they do not have a beautiful structure that the bosonized theory has and also give an inconsistent result when they include an ill-defined correlator with the divergence. We solve them and compute the several normalization independent ratios of the well-defined correlators, which agree with the matrix model results.Comment: Latex, 22 page

Teleportation and entanglement distillation in the presence of correlation among bipartite mixed states

The teleportation channel associated with an arbitrary bipartite state denotes the map that represents the change suffered by a teleported state when the bipartite state is used instead of the ideal maximally entangled state for teleportation. This work presents and proves an explicit expression of the teleportation channel for the teleportation using Weyl's projective unitary representation of the space of 2n-tuples of numbers from Z/dZ for integers d>1, n>0, which has been known for n=1. This formula allows any correlation among the n bipartite mixed states, and an application shows the existence of reliable schemes for distillation of entanglement from a sequence of mixed states with correlation.Comment: 12 pages, 1 figur

International flow of Zambian nurses

This commentary paper highlights changing patterns of outward migration of Zambian nurses. The aim is to discuss these pattern changes in the light of policy developments in Zambia and in receiving countries

Efeito das mudanças climáticas sobre a duração da fase lagarta do curuquerê-do-algodoeiro no nordeste brasileiro.

Resumo: Este trabalho teve como objetivo avaliar o impacto das mudanças climáticas no desenvolvimento de uma das mais importantes pragas desfolhadoras do algodão no Nordeste brasileiro, o curuquerê-do-algodoeiro Alabama argillacea (Hübner) na fase larval, utilizando Sistema de Informações Geográficas. A ocorrência do curuquerê-do-algodoeiro foi estimada empregando-se o modelo de desenvolvimento proposto por Kasten Junior e Parra (1984). Foram elaborados mapas que simulam a duração em dias da fase larval do inseto para o Nordeste no período de referência (1961-1990) e nas condições climáticas futuras projetadas pelo IPCC, nos períodos de 2011-2040, 2041-2070, 2071-2100, no cenário A2. Os resultados indicam que no futuro, de um modo geral, haverá uma diminuição da duração em dias da fase larval, implicando em aumento nas populações do curuquerê-do-algodoeiro, comparado ao período de 1961 a 1990 no Nordeste. Abstract: The objective of this study was to evaluate the impact of the climate change on the development of one of the most important cotton leaf defoliator pest in the Brazilian Northeast, the leafworm Alabama argillacea (Hübner) in larval stage, using Geographic Information System. The occurrence of leaf worm on cotton was estimated using the model of development proposed by Kasten Junior and Parra (1984). Maps were prepared to simulate the duration in days of the leafworm on cotton larval stage, to the Northeast in the reference period (1961-1990) and future climate conditions projected by the IPCC for the periods of 2011-2040, 2041-2070, 2071 - 2100, A2 scenario. The results indicate that in the future, generally, there will be a decrease in the duration in days of the larval stage implying the increase of the population of the cotton leafworm compared to the period of 1961 to 1990 in the Northeast region

RNA secondary structure prediction from multi-aligned sequences

It has been well accepted that the RNA secondary structures of most functional non-coding RNAs (ncRNAs) are closely related to their functions and are conserved during evolution. Hence, prediction of conserved secondary structures from evolutionarily related sequences is one important task in RNA bioinformatics; the methods are useful not only to further functional analyses of ncRNAs but also to improve the accuracy of secondary structure predictions and to find novel functional RNAs from the genome. In this review, I focus on common secondary structure prediction from a given aligned RNA sequence, in which one secondary structure whose length is equal to that of the input alignment is predicted. I systematically review and classify existing tools and algorithms for the problem, by utilizing the information employed in the tools and by adopting a unified viewpoint based on maximum expected gain (MEG) estimators. I believe that this classification will allow a deeper understanding of each tool and provide users with useful information for selecting tools for common secondary structure predictions.Comment: A preprint of an invited review manuscript that will be published in a chapter of the book `Methods in Molecular Biology'. Note that this version of the manuscript may differ from the published versio

A Unified Approach to Solvable Models of Dilaton Gravity in Two-Dimensions Based on Symmetry

A large class of solvable models of dilaton gravity in two space-time dimensions, capable of describing black hole geometry, are analyzed in a unified way as non-linear sigma models possessing a special symmetry. This symmetry, which can be neatly formulated in the target-space-covariant manner, allows one to decompose the non-linearly interacting dilaton-gravity system into a free field and a field satisfying the Liouville equation with in general non-vanishing cosmological term. In this formulation, all the existent models are shown to fall into the category with vanishing cosmological constant. General analysis of the space-time structureinduced by a matter shock wave is performed and new models, with and without the cosmological term, are discussed.Comment: 29 pages, LaTe

Anomalous Shift of Chemical Potential in the Double-Exchange Systems

Double-exchange system is investigated by the dynamical mean-field theory. We show that the chemical potential shifts as a function of temperature and magnetization, which is anomalously large. We also discuss the influences of dynamic Jahn-Teller effect to the shift of the chemical potential. Measurement of the shift of the chemical potential casts a constraint to theoretical approaches for the magnetoresistance phenomena in ($R$,$A$)MnO$_3$ such as double-exchange effects and dynamic Jahn-Teller effects. We also propose a method to measure the shift of $\mu$.Comment: Reference added, to be published in J. Phys. Soc. Jpn. Vol. 66 No.8 (Aug. 1997