2,230 research outputs found
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
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
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
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
The effect of geometry on charge confinement in three dimensions
We show that, in contrast to the flat case, the Maxwell theory is not
confining in the background of the three dimensional BTZ black-hole (covering
space). We also study the effect of the curvature on screening behavior of
Maxwell-Chern-Simons model in this space-time.Comment: 8 pages. To be published in Europhysics Letter
Intraoperative management of liver transplantation for familial amyloid polyneuropathy Met30: what has changed in the last 10 years?
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
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