Background Free Quantum Gravity based on Conformal Gravity and Conformal Field Theory on M^4

We study four dimensional quantum gravity formulated as a certain conformal field theory at the ultraviolet fixed point, whose dynamics is described by the combined system of Riegert-Wess-Zumino and Weyl actions. Background free nature comes out as quantum diffeomorphism symmetry by quantizing the conformal factor of the metric field nonperturbatively. In this paper, Minkowski background M^4 is employed in practice. The generator of quantum diffeomorphism that forms conformal algebra is constructed. Using it, we study the composite scalar operator that becomes a good conformal field. We find that physical fields are described by such scalar fields with conformal dimension 4. Consequently, tensor fields outside the unitarity bound are excluded. Computations of quantum algebra on M^4 are carried out in the coordinate space using operator products of the fields. The nilpotent BRST operator is also constructed.Comment: 43 pages, eqs.(3.9) and (6.18) correcte

CAPM and Option Pricing with Elliptical Disbributions

In this paper, we offer an alternative proof of the Capital Asset Pricing Model when the returns follow a multivariate elliptical distribution. Empirical studies continue to demonstrate the inappropriateness of the normality assumption in modelling asset returns. The class of elliptical distributions,which includes the more familiar Normal distribution, provides flexibility in modelling the thickness of tails associated with the possibility that asset returns take extreme values with non-negligible probabilities. Within this framework, we prove a new version of Stein's lemma for elliptical distribution and use this result to derive the CAPM when returns are elliptical. We also derive a closed form solution of call option prices when the underlying is elliptically distributed. We use the probability distortion function approach based on the dual utility theory of choice under uncertainty.

BRST Invariant Higher Derivative Operators in 4D Quantum Gravity based on CFT

We continue the study of physical fields for the background free 4D quantum gravity based on the Riegert-Wess-Zumino action, developed in Phys. Rev. D {\bf 85} (2012) 024028. The background free model is formulated in terms of a certain conformal field theory on M^4 in which conformal symmetry arises as gauge symmetry, namely diffeomorphism invariance. In this paper, we construct the physical field operator corresponding to any integer power of Ricci scalar curvature in the context of the BRST quantization. We also discuss how to define the correlation function and its physical meanings.Comment: 22 pages, minor typo corrected, published versio

On the dynamics of vortex modes within magnetic islands

Recent work investigating the interaction of magnetic islands with micro-turbulence has uncovered the striking observation of large scale vortex modes forming within the island structure [W.A. Hornsby {\it et al.}, Phys. Plasmas {\bf 17} 092301 (2010)]. These electrostatic vortices are found to be the size of the island and are oscillatory. It is this oscillatory behaviour and the presence of turbulence that leads us to believe that the dynamics are related to the Geodesic Acoustic Mode (GAM), and it is this link that is investigated in this paper. Here we derive an equation for the GAM in the MHD limit, in the presence of a magnetic island modified three-dimensional axisymmetric geometry. The eigenvalues and eigenfunctions are calculated numerically and then utilised to analyse the dynamics of oscillatory large-scale electrostatic potential structures seen in both linear and non-linear gyro-kinetic simulations

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

Métodos para estudar os efeitos das mudanças climáticas sobre doenças de plantas.

As mudanças climáticas causarão modificações na ocorrência de doenças de plantas, as quais estão entre os principais fatores responsáveis por reduções da produtividade agrícola. Esses impactos podem colocar em risco a sustentabilidade do agronegócio, devido às consequências econômicas, sociais e ambientais. O estudo dessas alterações tem a finalidade de fornecer subsídios para a elaboração de estratégias de adaptação. Muitos métodos estão descritos para avaliar os efeitos do ambiente sobre doenças de plantas, entretanto, o estudo das mudanças climáticas impõe algumas particularidades na utilização desses métodos. Garrett et al. (2006) apresentaram uma revisão sobre diferentes abordagens para o estudo do assunto, considerando diversas escalas de interação patógeno-hospedeiro, desde o microclima até o clima global. Posteriormente, Garrett et al. (2011) elaboraram um esquema para a análise da complexidade dos impactos das mudanças climáticas, baseado em um conjunto de perguntas para um determinado hospedeiro, patógeno, combinação patógeno-hospedeiro e região geográfica. Segundo os autores, na prática, pode ser necessário expandir os modelos com a inclusão de novos componentes, identificar os componentes mais importantes, ou sintetizar tais modelos até o nível ótimo de complexidade para o planejamento e priorização de pesquisa. No presente texto serão discutidas três abordagens para o estudo dos efeitos das mudanças climáticas sobre doenças de plantas: uso de séries históricas, experimentação e modelagem

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

Efecto del cambio climático sobre problemas fitosanitarios en caña de azúcar, maní y algodón: un abordaje binacional.

La roya marrón y la roya anaranjada de la caña de azúcar, la viruela tardía del maní y el picudo del algodonero son problemas fitosanitarios actuales y potenciales para estos cultivos industriales tanto en Argentina como en Brasil. En Argentina no se han realizado estudios sobre el efecto del cambio climático en cultivos que ocupan actualmente áreas bien definidas, con perspectivas de expandirse a otras áreas agroecológicas, generando flujos de patógenos y plagas en macroregiones abarcando ambos países. Para ello se elaboró un proyecto interinstitucional entre INTA y EMBRAPA cuyo objetivo principal es evaluar el impacto del cambio climático sobre enfermedades y plagas de cultivos de importancia para la agroindustria de Argentina y Brasil, intentando el desarrollo de alternativas de adaptación para su control en los escenarios climáticos futuros. La investigación y discusión en red entre Argentina y Brasil es una oportunidad indispensable para evitar esfuerzos innecesarios, integrando los resultados obtenidos con los diferentes cultivos de importancia para la agroindustria