Euclidean Scalar Green Function in a Higher Dimensional Global Spacetime

We construct the explicit Euclidean scalar Green function associated with a massless field in a higher dimensional global monopole spacetime, i.e., a $(1+d)$-spacetime with $d\geq3$ which presents a solid angle deficit. Our result is expressed in terms of a infinite sum of products of Legendre functions with Gegenbauer polynomials. Although this Green function cannot be expressed in a closed form, for the specific case where the solid angle deficit is very small, it is possible to develop the sum and obtain the Green function in a more workable expression. Having this expression it is possible to calculate the vacuum expectation value of some relevant operators. As an application of this formalism, we calculate the renormalized vacuum expectation value of the square of the scalar field, $_{Ren.}$, and the energy-momentum tensor, $_{Ren.}$, for the global monopole spacetime with spatial dimensions $d=4$ and $d=5$.Comment: 18 pages, LaTex format, no figure

f(R)f(R) global monopole revisited

In this paper the $f(R)$ global monopole is reexamined. We provide an exact solution for the modified field equations in the presence of a global monopole for regions outside its core, generalizing previous results. Additionally, we discuss some particular cases obtained from this solution. We consider a setup consisting of a possible Schwarzschild black hole that absorbs the topological defect, giving rise to a static black hole endowed with a monopole's charge. Besides, we demonstrate how the asymptotic behavior of the Higgs field far from the monopole's core is shaped by a class of spacetime metrics which includes those ones analyzed here. In order to assess the gravitational properties of this system, we analyse the geodesic motion of both massive and massless test particles moving in the vicinity of such configuration. For the material particles we set the requirements they have to obey in order to experience stable orbits. On the other hand, for the photons we investigate how their trajectories are affected by the gravitational field of this black hole.Comment: 16 pages, 1 figure and 1 table. Minor changes to match published version in EPJ

Review of a Small-scale Pelagic Longline Fishery off Northeastern Brazil

The annual catches of four small longliners operating off northeast Brazil from 1983 to 1997 were examined across different areas and locations. The total catch comprised tunas (30%), sharks (54%), billfishes (12%), and other fish species (4%). Fishing strategy and annual composition of catches showed large spatial and temporal variabilities with the dominant catches alternating among yellowfin tuna, Thunnus albacares; gray sharks, Carcharhinus spp.; and blue shark, Prionace glauca. Catches of blue and gray sharks showed a significant interaction among seamounts, with gray sharks occurring in maximum abundance around those seamounts that had relatively deep summits and low-sloping depth profiles. Results are discussed in terms of the various factors that may have influenced distribution of effort

Caracterização físico-química de clones e progênies de cupuaçuzeiro (Theobroma grandiflorum).

O cupuaçu tem despertado interesse entre fruticultores da região Norte do país, devido ao aumento da demanda pelo fruto, notadamente pelas suas peculiaridades organolépticas, destacando-se sabor e aroma. Como a cultura está disseminada por todo o Amapá, a Embrapa Amapá introduziu clones e progênies de várias localidades em 1998 e 1999, gerando grande fonte de informações de caráter agronômico dos materiais genéticos, assim como de aspectos físico-químicos dos frutos. Em 2004, com o objetivo de analisar as polpas quanto às suas características físico-químicas, 19 materiais, entre clones e progênies, foram testados no delineamento experimental blocos casualizados, em três repetições e os resultados comparados à legislação sobre Padrões de Identidade e Qualidade para polpa de cupuaçu do MAPA. Os materiais apresentaram uma grande variabilidade quanto às características estudadas. Em relação aos sólidos totais, destacaram-se as progênies 11 (26,7g/100g) e 47 (23,6g/100g), enquanto que as progênies 03 (9,1g/1OOg) e 41 (9g/100g) não alcançaram o mínimo previsto na legislação (12g/100g). Observou-se que os materiais apresentaram valores muito reduzidos de ácido cítrico (1,2g/100g), tendo somente o clone 04-618 (1,8g/100g)alcançado valor superior ao padrão (1,5g/100g). O valor médio de pH das polpas (3,6) revelou que os materiais apresentaram valores muito superiores à legislação (2,6), destacando-se significativamente a progênie 46 (4,4). Também em relação aos sólidos solúveis, expressos em °Brix, observou-se que todos os materiais superaram o padrão previsto na legislação (9°Brix), tendo as progênies 46 (15,5°Brix), 76 (15,2°Brix), o clone 01-211 e a progênie 59 (15,1°Brix) se destacado significativamente. Teores de extrato etéreo dos materiais alcançaram média de 1,7g/100g, destacando-se significativamente a progênie 12 (2,9g/100g), assim como o clone F-212 e a progênie 47 (2,3g/100g). Reunindo as características estudadas e comparando com os teores mínimos da regulamentação de polpa de cupuaçu, conclui-se que apenas o clone 04-618 alcançou os padrões de identidade e qualidade

Scalar and Spinor Particles in the Spacetime of a Domain Wall in String Theory

We consider scalar and spinor particles in the spacetime of a domain wall in the context of low energy effective string theories, such as the generalized scalar-tensor gravity theories. This class of theories allows for an arbitrary coupling of the wall and the (gravitational) scalar field. First, we derive the metric of a wall in the weak-field approximation and we show that it depends on the wall's surface energy density and on two post-Newtonian parameters. Then, we solve the Klein-Gordon and the Dirac equations in this spacetime. We obtain the spectrum of energy eigenvalues and the current density in the scalar and spinor cases, respectively. We show that these quantities, except in the case of the energy spectrum for a massless spinor particle, depend on the parameters that characterize the scalar-tensor domain wall.Comment: LATEX file, 21 pages, revised version to appear in Phys. Rev.

Relativistic Quantum Scattering on a Cone

We study the relativistic quantum mechanical scattering of a bosonic particle by an infinite straight cosmic string, considering the non-minimal coupling between the bosonic field and the scalar curvature. In this case, an effective two-dimensional delta-function interaction takes place besides the usual topological scattering and a renormalization procedure is necessary in order to treat the problem that appears in connection with the delta-function.Comment: 22 pages, LATEX fil

On Matrix Superpotential and Three-Component Normal Modes

We consider the supersymmetric quantum mechanics (SUSY QM) with three- component normal modes for the Bogomol'nyi-Prasad-Sommerfield (BPS) states. An explicit form of the SUSY QM matrix superpotential is presented and the corresponding three-component bosonic zero-mode eigenfunction is investigated.Comment: 17 pages, no figure. Paper accepted for publication in Journal of Physics A: Mathematical and Theoretica

Quantum walk-based search algorithms with multiple marked vertices

The quantum walk is a powerful tool to develop quantum algorithms, which usually are based on searching for a vertex in a graph with multiple marked vertices, Ambainis's quantum algorithm for solving the element distinctness problem being the most shining example. In this work, we address the problem of calculating analytical expressions of the time complexity of finding a marked vertex using quantum walk-based search algorithms with multiple marked vertices on arbitrary graphs, extending previous analytical methods based on Szegedy's quantum walk, which can be applied only to bipartite graphs. Two examples based on the coined quantum walk on two-dimensional lattices and hypercubes show the details of our method.Comment: 12 pages, 1 table, 2 fig

Self-forces in the Spacetime of Multiple Cosmic Strings

We calculate the electromagnetic self-force on a stationary linear distribution of four-current in the spacetime of multiple cosmic strings. It is shown that if the current is infinitely thin and stretched along a line which is parallel to the strings the problem admits an explicit solution.Comment: This paper has been produced in Latex format and has 18 page