5,227 research outputs found
Solid State Analog for He-McKellar-Wilkens Quantum Phase
In this letter we investigate the quantum dynamics of a quasiparticle in the
presence of a charged screw dislocation submitted to a uniform magnetic field.
Analysing the quantum scattering for this quasiparticle we observed the
appearance of a topological quantum phase in the solution and demonstrate that
this phenomenon is the solid state analog of the He-McKeller-Wilkens effect.Comment: 7 pages, epl styl
A worldwide model for boundaries of urban settlements
The shape of urban settlements plays a fundamental role in their sustainable
planning. Properly defining the boundaries of cities is challenging and remains
an open problem in the Science of Cities. Here, we propose a worldwide model to
define urban settlements beyond their administrative boundaries through a
bottom-up approach that takes into account geographical biases intrinsically
associated with most societies around the world, and reflected in their
different regional growing dynamics. The generality of the model allows to
study the scaling laws of cities at all geographical levels: countries,
continents, and the entire world. Our definition of cities is robust and holds
to one of the most famous results in Social Sciences: Zipf's law. According to
our results, the largest cities in the world are not in line with what was
recently reported by the United Nations. For example, we find that the largest
city in the world is an agglomeration of several small settlements close to
each other, connecting three large settlements: Alexandria, Cairo, and Luxor.
Our definition of cities opens the doors to the study of the economy of cities
in a systematic way independently of arbitrary definitions that employ
administrative boundaries
On aether terms in a space-time with a compact extra dimension
In this paper, for the CPT-even and CPT-odd extensions of the QED, we
explicitly obtain the aether-like corrections for the electromagnetic field in
the case when the space-time involves an extra compact spatial dimension
besides of usual four dimensions. Our methodology is based on an explicit
summation over the Kaluza-Klein tower of fields which is no more difficult than
the finite-temperature calculations. The quantum corrections turn out to be
large as the extra dimension is small. We demonstrate that in the CPT-even
case, the extra dimension manifests itself through a new scalar particle.Comment: 9 page
Embrapa y el desarrollo de productos basados en la tilapia.
bitstream/item/28063/1/2010-001.pd
The Godel metric in the Chern-Simons modified gravity
We discuss the consistency of the Godel metric within the Chern-Simons
modified gravity, both for external and dynamical Chern-Simons coefficients.Comment: 6 pages; to be published in the Proceedings of 5th International
Workshop on Astronomy and Relativistic Astrophysics (IWARA 2011), matches the
accepted versio
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