Cusp Anomalous dimension and rotating open strings in AdS/CFT

In the context of AdS/CFT we provide analytical support for the proposed duality between a Wilson loop with a cusp, the cusp anomalous dimension, and the meson model constructed from a rotating open string with high angular momentum. This duality was previously studied using numerical tools in [1]. Our result implies that the minimum of the profile function of the minimal area surface dual to the Wilson loop, is related to the inverse of the bulk penetration of the dual string that hangs from the quark--anti-quark pair (meson) in the gauge theory.Comment: enhanced text, fixed tipos, reference added. Same results and conclusions. arXiv admin note: text overlap with arXiv:1405.7388 by other author

Holography andquantum information

Entanglement is the most counterintuitive feature in quantum mechanics. In recent years, it has been pointed out a deep connection between entanglement and the connectivity of spacetime in the context of AdS/CFT or Holography. The AdS/CFT correspondence states the duality between quantum field theories in d-spacetime dimensions and quantum gravity in at least one extra dimension. This theoretical framework has led to profound consequences and insights for both sides. In this thesis, we study three aspects of entanglement entropy in holography: traversable wormholes, modular Berry phases, and entanglement islands. In Chapter 1, we explain how these concepts are intimately related with entanglement entropy. In Chapter 2, we review the non-local protocol that allows for traversable wormholes using ordinary matter and we implement it to construct an eternal traversable wormhole in asymptotically anti-de Sitter spacetime in four dimensions. We then review the modular Berry transport problem. In the context of three-dimensional gravity, in Chapter 3, we study the parallel transport of modular Hamiltonians governed by a change of global state. We relate the Berry curvature for a fixed interval with the symplectic form for a Euclidean conical singularity geometry obtained from the backreaction of a cosmic brane. Finally, after reviewing the island formula and its use in the resolution of some aspects of the black hole information paradox, we discuss its possible application in cosmology. We study the possible existence of islands in FRW cosmologies supported by thermal radiation, cosmological constant, and non-zero spatial curvature in Chapter 4

A new species of Corydoras Lacépède (Siluriformes: Callichthyidae) from the Rio Tapajós basin and its phylogenetic implications

A new species of Corydoras is described from tributaries of the rio Arinos, rio Teles Pires and rio Preto, all in the rio Tapajós basin. The new species is a member of a group that includes 36 species with spots on the body. Within this group, the new species can be readily distinguished by having a smaller dorsal-fin spine than the first three subsequent soft dorsal-fin rays; pectoral, pelvic and anal fins hyaline; dorsal-fin interradial membrane hyaline; rounded spots on trunk restricted to dorsolateral body plates and dorsal portion of ventrolateral body plates, not reaching the base of pelvic and anal fins. The new species can be further distinguished from Corydoras xinguensis by having spots with diffuse edges, and from all other species of spotted Corydoras except C.multimaculatus, by the absence of ventral platelets. A phylogenetic analysis recovered the new species plus Corydoras metae and C.araguaiensis in a clade sharing the presence of a pointed process on the maxilla for insertion of the retractor tentaculi muscle. In addition, the presence in the new species of an elongated anterior portion of the mesethmoid and a triangular uncinate process of the epibranchial 3 suggests a close relationship with Corydoras metae.Uma nova espécie de Corydoras é descrita dos tributários dos rios Arinos, Teles Pires e Preto, bacia do rio Tapajós. A nova espécie é membro de um grupo com pontilhados no corpo que inclui 36 espécies. Dentro desse grupo, a nova espécie pode ser facilmente distinguida pelo espinho dorsal menor que os três primeiros raios ramificados da nadadeira dorsal; nadadeiras peitorais, pélvicas e anal hialinas; membranas inter-radiais da nadadeira dorsal hialina; presença de pontilhados redondos no tronco restritas as placas dorsolaterais do corpo e porções dorsais das placas ventrolaterais não alcançando a base das nadadeiras pélvicas e anal. A nova espécie pode ser distinguida de Corydoras xinguensis por pontilhados com margens difusas e das demais espécies de Corydoras com pontilhado, exceto em C.multimaculatus, pela ausência de pequenas placas ventrais. Uma análise filogenética recuperou a nova espécie mais Corydoras metae e C.araguaiensis em um agrupamento compartilhando a presença de um processo pontiagudo para inserção do músculo retractor tentaculi no maxilar. A porção anterior do mesetmóide alongada e o processo uncinado do epibranquial 3 triangular indicam uma relação mais próxima com Corydoras metae

Rural-urban migration in d-dimensional lattices

The rural-urban migration phenomenon is analyzed by using an agent-based computational model. Agents are placed on lattices which dimensions varying from d=2 up to d=7. The localization of the agents in the lattice define their social neighborhood (rural or urban) not being related to their spatial distribution. The effect of the dimension of lattice is studied by analyzing the variation of the main parameters that characterizes the migratory process. The dynamics displays strong effects even for around one million of sites, in higher dimensions (d=6, 7).Comment: 9 pages, 7 figures, to be published in International Journal of Modern Physics C 1

Photoelectrocatalytic inactivation of Pseudomonas aeruginosa using an Ag-decorated TiO2 photoanode

Fast and total inactivation of Gram-negativePseudomonas aeruginosain suspensions at natural pH 5.9 has beenachieved by photoelectrocatalyisis (PEC), using Ag-decorated TiO2photoanodes onto transparent conductingindium tin oxide (ITO) under UVA irradiation. The assays were made with 100 mL of bacterial suspensions in anundivided cell equipped with a photoanode, a stainless steel cathode and Ag|AgCl (3 M KCl) as referenceelectrode. Total inactivation was obtained in only 5 min using coatings with 4 wt.% Ag, 25 mM Na2SO4as theelectrolyte and 1.70 V as applied bias potential. Comparative photocatalytic treatments reached total inactiva-tion at much longer time, suggesting the crucial role of hydroxyl radicals in PEC. These oxidants, which weredetected by electron spin resonance, attacked the outer cell wall very effectively, since the recombination of theelectron/hole pairs photoinduced under UVA irradiation was reduced. As characterized by high-resolutiontransmission electron microscopy (HRTEM), the best synthesized Ag-TiO2thin-film photoanode mainly containsanatase TiO2nanopowder decorated with Ag nanoparticles of ca. 45 nm. Analyses by X-ray powder diffractionand UV/Vis spectroscopy were also performed. The potential use of PEC for bacterial disinfection was confirmedfor the rod-shaped Gram-positiveBacillus atrophaeus, which was more slowly inactivated due to its different cellwall structure. Scanning electron micrographs of both bacteria showed that PEC induced a high roughness, celllysis and accumulation of cellular debris

Energy transfer, structural and luminescent properties of the color tunable Phosphor Y2WO6:Sm3+

Inorganic phosphors based on monoclinic Y2WO6 doped with Sm3þ ions were prepared via conventional solid-state reactions at high temperature. A total of six samples were obtained with different Sm3þ concentrations (0e9%). The purity of the as-prepared phases was checked by powder X-ray diffraction (PXRD). The excitation, emission, and time-resolved emission spectra were examined in detail. The experimental decay curves were fitted to the InokutieHirayama model, showing that the Sm3þ ions form clusters at all compositions. Periodic hybrid density functional theory calculations were also carried out on the undoped material and on 144-atom supercells of stoichiometry Y1.9375Sm0.0625WO6 and Y1.875Sm0.125WO6. The different coordination environments at the Y1, Y2 and Y3 sites are analysed in detail. The calculated structure and band gap of Y2WO6 are in good agreement with experiment with one potentially important discrepancy in a Y3eO bond length. The thermodynamically favoured substitution sites for Sm, Y2 and Y3, in the supercell are not those observed under the preparation conditions used here, since the experimental Rietveld analysis suggests occupation of Y1 at all concentrations. Analogous calculations for the Eu- doped system highlight marked differences between Eu and Sm despite their similar ionic sizes. The calculated densities of states show the position of the 4f levels in the band gap depend on the sites occupied by the dopants and thus expect marked differences in the luminescence spectra, opening up possibilities for tuning device performance

Microbial activity in a degraded Latosol treated with sewage sludge

The degraded soil shows, in general, poor biological activity, considering its physical characteristics, low fertility and organic matter, mainly due to removal or degradation of its superficial layer. The sewage sludge, due to its high content of easily decomposed organic matter can be an alternate source of organic residues and combined to its high content of the principal nutrients for the plants can be an important factor to promote biological activities in degraded soil. In order to study the actions of the sewage sludge in the recovery of a degraded Latosol, the carbon in the microbial biomass (Cmic), the carbon released CO2 (C-CO2) and the relation between microbial and organic carbon (Cmic/Corg) were used as indicators of the effects. To do so, two doses (30 and 60 Mg ha-1) of sewer slime applied in topdressing and incorporated together with a mineral fertilizer treatment, using the eucalyptus as a test crop. A completely randomized design with 4 treatments and 4 repetitions was used. The sewage sludge promoted increase of liberated C-CO2 and the Cmic, which constitute the adequate quality indicators for monitoring the soil recovery.Em geral, os solos degradados se apresentam com fraca atividade biológica, tendo em vista suas características físicas, baixa fertilidade e teores de matéria orgânica, devido principalmente à remoção ou degradação de sua camada superficial. O elevado teor de matéria orgânica facilmente decomposta do lodo de esgoto, que é uma fonte alternativa de resíduos orgânicos, aliado à sua elevada taxa dos principais elementos nutrientes às plantas, pode ser um fator importante do retorno ou incremento da atividade biológica dos solos degradados. Com a finalidade de se estudar as ações do lodo de esgoto na recuperação de um Latossolo degradado, utilizaram-se, como indicadores dos efeitos, o carbono na biomassa microbiana (Cmic), o carbono do CO2 (C-CO2) liberado e a relação entre o carbono microbiano e o carbono orgânico (Cmic/Corg); para isto, foram definidas duas doses de lodo de esgoto aplicadas em cobertura e incorporada, de 30 e 60 Mg ha-1 à base seca, juntamente com um tratamento com fertilizante mineral, utilizando-se o eucalipto como cultura teste. O delineamento experimental foi o inteiramente casualizado, com 4 tratamentos e 4 repetições. O lodo de esgoto promove aumento do C-CO2 liberado e do Cmic, os quais constituem indicativos de qualidade adequados ao monitoramento da recuperação do solo.19519