Lorentz symmetry breaking effects on relativistic EPR correlations

Lorentz symmetry breaking effects on relativistic EPR (Einstein-Podolsky-Rosen) correlations are discussed. From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the Lorentz symmetry violation and write an effective metric for the Minkowski spacetime. Then, we obtain the Wigner rotation angle via the Fermi-Walker transport of spinors and consider the WKB ((Wentzel-Kramers-Brillouin) approximation in order to study the influence of Lorentz symmetry breaking effects on the relativistic EPR correlations.Comment: Accepted for publication in The European Physical Journal C. arXiv admin note: substantial text overlap with arXiv:1504.07432, arXiv:1504.07262, arXiv:1412.5080, arXiv:1506.0056

Collaboration networks from a large CV database: dynamics, topology and bonus impact

Understanding the dynamics of research production and collaboration may reveal better strategies for scientific careers, academic institutions and funding agencies. Here we propose the use of a large and multidisciplinar database of scientific curricula in Brazil, namely, the Lattes Platform, to study patterns of scientific production and collaboration. In this database, detailed information about publications and researchers are made available by themselves so that coauthorship is unambiguous and individuals can be evaluated by scientific productivity, geographical location and field of expertise. Our results show that the collaboration network is growing exponentially for the last three decades, with a distribution of number of collaborators per researcher that approaches a power-law as the network gets older. Moreover, both the distributions of number of collaborators and production per researcher obey power-law behaviors, regardless of the geographical location or field, suggesting that the same universal mechanism might be responsible for network growth and productivity.We also show that the collaboration network under investigation displays a typical assortative mixing behavior, where teeming researchers (i.e., with high degree) tend to collaborate with others alike. Finally, our analysis reveals that the distinctive collaboration profile of researchers awarded with governmental scholarships suggests a strong bonus impact on their productivity.Comment: 8 pages, 8 figure

Gravitational Geometric Phase in the Presence of Torsion

We investigate the relativistic and non-relativistic quantum dynamics of a neutral spin-1/2 particle submitted an external electromagnetic field in the presence of a cosmic dislocation. We analyze the explicit contribution of the torsion in the geometric phase acquired in the dynamic of this neutral spinorial particle. We discuss the influence of the torsion in the relativistic geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic quantum dynamics are studied and the influence of the torsion in the Aharonov-Casher and He-McKellar-Wilkens effects are discussed.Comment: 14 pages, no figur

Self-Forces on Electric and Magnetic Linear Sources in the Space-Time of a Cosmic String

In this paper we calculate the magnetic and electric self-forces, induced by the conical structure of a cosmic string space-time, on a long straight wire which presents either a constant current or a linear charge density. We also show how these self-forces are related by a Lorentz tranformation and, in this way, explain what two different inertial observers detect in their respective frames.Comment: 10 pages, LaTeX, to be published in Phys. Rev. D

Electronic properties of curved graphene sheets

A model is proposed to study the electronic structure of slightly curved graphene sheets with an arbitrary number of pentagon-heptagon pairs and Stone-Wales defects based on a cosmological analogy. The disorder induced by curvature produces characteristic patterns in the local density of states that can be observed in scanning tunnel and transmission electron microscopy.Comment: Corrected versio

Estudo dos postos de trabalho de inspecção de defeitos da indústria têxtil

Pretende-se com esta comunicação apresentar o trabalho desenvolvido no âmbito da campanha Têxtil do IDICT, onde se realizou um estudo dos postos de trabalho de inspecção de defeitos da Industria Têxtil. O trabalho centrou-se particularmente nos aspectos Ergonómicos dos postos de trabalho: “Metedeira de Fios”, “Revistadeira” e “Inspecção Final”. Cada um dos postos de trabalho foi caracterizado em função dos seguintes aspectos: características gerais; postura e trabalho muscular; percepção, vigilância e destreza; ambiente físico e organização do trabalho. O modelo de actuação usado consistiu na realização de uma série de questões, cuja resposta conduziu à elaboração de um pré-diagnóstico dos postos de trabalho de inspecção. Este pré-diagnóstico constitui, por sua vez, a base para a proposta de um conjunto de recomendações e sugestões ao nível da iluminação, ruído, aspectos ergonómicos do assento e medidas administrativas

Sistema automático para inspecção visual de defeitos em tecidos

Pretende-se com esta comunicação apresentar o trabalho desenvolvido no âmbito da Campanha Têxtil do IDICT, onde se aplicaram algoritmos de processamento de imagem à inspecção de defeitos em tecidos. Devido à complexidade do problema em estudo foi necessário construir um sistema de iluminação estruturada para garantir luminosidade constante no tecido a inspeccionar. Um sistema de captura e processamento de imagens a cores foi desenvolvido, para o sistema operativo Windows 98, tendo por base a placa de aquisição Matrox Meteor II e o software Microsoft Visual C++. Após a conversão de imagens a cores em níveis de cinzento foram desenvolvidos algoritmos de binarização, baseados em análise estatística e morfologia matemática. Os algoritmos desenvolvidos abrangem os seguintes defeitos em tecidos: falta de fio, fio grosso, fio duplo, borboto, mancha e nódoa. Para cada tecido a inspecionar é necessário um período de treino do sistema de forma a identificar os parâmetros estatísticos que o caracterizam, média e desvio padrão dos níveis de cinzento. O sistema inspecciona de forma automática os defeitos descritos em tecidos penteados de uma só cor, tendo sido obtidos resultados bastante satisfatórios para o número de tecidos disponibilisados pelas empresas da região

Peritoneal and hepatic hydatid disease causing major bile duct destruction

Echinococcosis is endemic in Mediterranean regions and is found primarily in the liver. Biliary fistula is a common complication, but major biliary duct involvement is very rare, and occurs in 0.47% of patients with hepatic hydatid disease. Cyst rupture causing secondary peritoneal hydatidosis is a rare but serious complication. We report the case of a 27-year-old man with multiple peritoneal and hepatic hydatid cysts. The patient came to our attention with cholestatic jaundice. Imaging exams showed numerous peritoneal cysts and massive hydatid disease of the liver, which involved the hepatic confluence, with destruction of the right hepatic duct and fistula formation to the left hepatic duct. The patient was treated with pre-operative albendazole therapy and radical surgery, which consisted of resection of all peritoneal cysts and extended right hepatectomy with biliary reconstruction. No recurrence was seen on CT investigations on the 12th month following surgery. Radical surgical approach remains the treatment of choice

Human Mobility in Large Cities as a Proxy for Crime

We investigate at the subscale of the neighborhoods of a highly populated city the incidence of property crimes in terms of both the resident and the floating population. Our results show that a relevant allometric relation could only be observed between property crimes and floating population. More precisely, the evidence of a superlinear behavior indicates that a disproportional number of property crimes occurs in regions where an increased flow of people takes place in the city. For comparison, we also found that the number of crimes of peace disturbance only correlates well, and in a superlinear fashion too, with the resident population. Our study raises the interesting possibility that the superlinearity observed in previous studies [Bettencourt et al., Proc. Natl. Acad. Sci. USA 104, 7301 (2007) and Melo et al., Sci. Rep. 4, 6239 (2014)] for homicides versus population at the city scale could have its origin in the fact that the floating population, and not the resident one, should be taken as the relevant variable determining the intrinsic microdynamical behavior of the system.Comment: 17 pages, 8 Figure