Closed string thermal torus from thermo field dynamics

In this Letter a topological interpretation for the string thermal vacuum in the thermo field dynamics (TFD) approach is given. As a consequence, the relationship between the imaginary time and TFD formalisms is achieved when both are used to study closed strings at finite temperature. The TFD approach starts by duplicating the system's degrees of freedom, defining an auxiliary (tilde) string. In order to lead the system to finite temperature a Bogoliubov transformation is implemented. We show that the effect of this transformation is to glue together the string and the tilde string to obtain a torus. The thermal vacuum appears as the boundary state for this identification. Also, from the thermal state condition, a Kubo-Martin-Schwinger condition for the torus topology is derived. © 2005 Elsevier B.V. All rights reserved.

Towards a hybrid compactification with a scalar-tensor global cosmic string

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Vacuum effects on massive spinor fields: S-1 x R-3 topology

The aim of this work was to investigate the role played by an external field on the Casimir energy density for massive fermions under S-1 x R-3 topology. Both twisted- and untwisted-spin connections are considered and the calculation in a closed form is performed using an alternative approach based on the combination of the analytic regularization method and the Euler-Maclaurin summation formula. It is shown that no mass scale appears in the final result and, therefore, Casimir effect arises only from the boundary conditions and vacuum fluctuations induced by the coupling with the external field.

Black string corrections in variable tension braneworld scenarios

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Low voltage four-quadrant current multiplier: An improved topology for n-well CMOS process

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Algoritmos evolutivos dedicados à reconfiguração de redes radiais de distribuição sob demandas fixas e variáveis: estudo dos operadores genéticos e parâmetros de controle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Low voltage four-quadrant current multiplier: an improved topology for n-well CMOS process

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

In silico network topology-based prediction of gene essentiality

The identification of genes essential for survival is important for the understanding of the minimal requirements for cellular life and for drug design. As experimental studies with the purpose of building a catalog of essential genes for a given organism are time-consuming and laborious, a computational approach which could predict gene essentiality with high accuracy would be of great value. We present here a novel computational approach, called NTPGE (Network Topology-based Prediction of Gene Essentiality), that relies on the network topology features of a gene to estimate its essentiality. The first step of NTPGE is to construct the integrated molecular network for a given organism comprising protein physical, metabolic and transcriptional regulation interactions. The second step consists in training a decision-tree-based machine-learning algorithm on known essential and non-essential genes of the organism of interest, considering as learning attributes the network topology information for each of these genes. Finally, the decision-tree classifier generated is applied to the set of genes of this organism to estimate essentiality for each gene. We applied the NTPGE approach for discovering the essential genes in Escherichia coli and then assessed its performance. (C) 2007 Elsevier B.V. All rights reserved.

Towards the prediction of essential genes by integration of network topology, cellular localization and biological process information

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The size of excavators within a polymorphic termite species governs tunnel topology

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structure of the posthepatic septum and its influence on visceral topology in the tegu lizard, Tupinambis merianae (Teiidae : Reptilia)

The posthepatic septum (PHS) divides the body cavity of Tupinambis merianae into two parts: the cranial one containing the lungs and liver and the caudal one containing the remaining viscera. The PHS is composed of layers of collagenous fibers and bundles of smooth muscle, neither of which show systematic orientation, as well as isolated blood vessels, lymphatic vessels, and nerves. Striated muscle of the abdominal wall does not invade the PHS. The contractions of the smooth muscles may stabilize the pleurohepatic cavity under conditions of elevated aerobic needs rather than supporting breathing on a breath-by-breath basis. Surgical removal of the PHS changes the anatomical arrangement of the viscera significantly, with stomach and intestine invading the former pleurohepatic cavity and reducing the space for the lungs, Thus, the PHS is essential to maintain the visceral topography in Tupitionibis. J. Morphol. 258:151-157, 2003. (C) 2003 Wiley-Liss. Inc.

Entropy of bosonic open string and boundary conditions

The entropy of the states associated to the solutions of the equations of motion of the bosonic open string with combinations of Neumann and Dirichlet boundary conditions is given. Also, the entropy of the string in the states \A(i)] = alpha(-1)(i)\0] and \phi(a)]= alpha(-1)(a)\0] that describe the massless fields on the world-volume of the Dp-brane is computed. (C) 2002 Elsevier B.V. B.V. All rights reserved.

The tachyon potential in open Neveu-Schwarz string field theory

A classical action for open superstring field theory has been proposed which does not suffer from contact term problems. After generalizing this action to include the non-GSO projected states of the Neveu-Schwarz string, the pure tachyon contribution to the tachyon potential is explicitly computed. The potential has a minimum of V = 1/32g(2) which is 60% of the predicted exact minimum of V = 1/2 pi(2)g(2) from D-brane arguments.

Quantum state density and critical temperature in M-theory

We discuss the asymptotic properties of quantum states density for fundamental p-branes which can yield a microscopic interpretation of the thermodynamic quantities in M-theory. The matching of the BPS part of spectrum for superstring and supermembrane gives the possibility of getting membrane's results via string calculations. In the weak coupling limit of M-theory, the critical behavior coincides with the first-order phase transition in the standard string theory at temperature less than the Hagedorn's temperature T-H. The critical temperature at large coupling constant is computed by considering M-theory on manifold with topology R-9 circle times T-2. Alternatively we argue that any finite temperature can be introduced in the framework of membrane thermodynamics.

Affine Toda model coupled to matter and the string tension in 2D QCD

The sl(2) affine Toda model coupled to matter is shown to describe various features, such as the spectrum and string tension, of the low-energy effective Lagrangian of two-dimensional QCD (one flavor and N colors). The corresponding string tension is computed when the dynamical quarks are in the fundamental representation of SU(N) and in the adjoint representation of SU(2).