7,111 research outputs found
The Relative Space: Space Measurements on a Rotating Platform
We introduce here the concept of relative space, an extended 3-space which is
recognized as the only space having an operational meaning in the study of the
space geometry of a rotating disk. Accordingly, we illustrate how space
measurements are performed in the relative space, and we show that an old-aged
puzzling problem, that is the Ehrenfest's paradox, is explained in this purely
relativistic context. Furthermore, we illustrate the kinematical origin of the
tangential dilation which is responsible for the solution of the Ehrenfest's
paradox.Comment: 14 pages, 2 EPS figures, LaTeX, to appear in the European Journal of
Physic
The Sagnac Effect in curved space-times from an analogy with the Aharonov-Bohm Effect
In the context of the natural splitting, the standard relative dynamics can
be expressed in terms of gravito-electromagnetic fields, which allow to
formally introduce a gravito-magnetic Aharonov-Bohm effect. We showed elsewhere
that this formal analogy can be used to derive the Sagnac effect in flat
space-time as a gravito-magnetic Aharonov-Bohm effect. Here, we generalize
those results to study the General Relativistic corrections to the Sagnac
effect in some stationary and axially symmetric geometries, such as the
space-time around a weakly gravitating and rotating source, Kerr space-time,
G\"{odel} universe and Schwarzschild space-time.Comment: 14 pages, 1 EPS figure, LaTeX, accepted for publication in General
Relativity and Gravitatio
Bimodal AGNs in Bimodal Galaxies
By their star content, the galaxies split out into a red and a blue
population; their color index peaked around u-r=2.5 or u-r=1, respectively,
quantifies the ratio of the blue stars newly formed from cold galactic gas, to
the redder ones left over by past generations. On the other hand, upon
accreting substantial gas amounts the central massive black holes energize
active galactic nuclei (AGNs); here we investigate whether these show a
similar, and possibly related, bimodal partition as for current accretion
activity relative to the past. To this aim we use an updated semianalytic
model; based on Monte Carlo simulations, this follows with a large statistics
the galaxy assemblage, the star generations and the black hole accretions in
the cosmological framework over the redshift span from z=10 to z=0. We test our
simulations for yielding in close detail the observed split of galaxies into a
red, early and a blue, late population. We find that the black hole accretion
activities likewise give rise to two source populations: early, bright quasars
and later, dimmer AGNs. We predict for their Eddington parameter --
the ratio of the current to the past black hole accretions -- a bimodal
distribution; the two branches sit now under (mainly
contributed by low-luminosity AGNs) and around . These
not only mark out the two populations of AGNs, but also will turn out to
correlate strongly with the red or blue color of their host galaxies.Comment: 7 pages, accepted for publication in the Astrophysical Journa
Fredkin Gates for Finite-valued Reversible and Conservative Logics
The basic principles and results of Conservative Logic introduced by Fredkin
and Toffoli on the basis of a seminal paper of Landauer are extended to
d-valued logics, with a special attention to three-valued logics. Different
approaches to d-valued logics are examined in order to determine some possible
universal sets of logic primitives. In particular, we consider the typical
connectives of Lukasiewicz and Godel logics, as well as Chang's MV-algebras. As
a result, some possible three-valued and d-valued universal gates are described
which realize a functionally complete set of fundamental connectives.Comment: 57 pages, 10 figures, 16 tables, 2 diagram
Social geography of rhinoscleroma and qualitatively and quantitatively abnormal cell-mediated immunity
Rhinoscleroma is a progressive chronic granulomatous disease of the upper respiratory tract that may extend to the tracheobronchial tract. It is common belief that the pathology is determined by Klebsiella Rhinoscleromatis. In the authors' opinion, the infection with Klebsiella Rhinoscleromatis may not represent the only etiopathogenic factor of the disease. Rhinoscleroma is reported in many countries, but has a peculiar social and geographic distribution, in that it assumes an endemic character only in some regions of the Middle East, West Russia, North Africa, Indonesia, Central and South America. In Europe, most of the cases are reported in Poland, Hungary and Romania. In Italy, Rhinoscleroma is almost exclusively located in the southern and island regions. Rhinoscleroma is predominantly reported in rural areas, in the presence of poor socio-economic conditions, which according to many authors would be a co-factor triggering the disease. In this article, the authors review some inconsistencies in etiology, histology and epidemiology of Rhinoscleroma. Based on the overall picture, they propose that intrinsic factors, possibly of genetic origin, may give rise to the disease, and suggest possible lines of research to distinguish between extrinsic and intrinsic factors as determinants for Rhinoscleroma
Classical BV theories on manifolds with boundary
In this paper we extend the classical BV framework to gauge theories on
spacetime manifolds with boundary. In particular, we connect the BV
construction in the bulk with the BFV construction on the boundary and we
develop its extension to strata of higher codimension in the case of manifolds
with corners. We present several examples including electrodynamics, Yang-Mills
theory and topological field theories coming from the AKSZ construction, in
particular, the Chern-Simons theory, the theory, and the Poisson sigma
model. This paper is the first step towards developing the perturbative
quantization of such theories on manifolds with boundary in a way consistent
with gluing.Comment: The second version has many typos corrected, references added. Some
typos are probably still there, in particular, signs in examples. In the
third version more typoes are corrected and the exposition is slightly
change
The Sagnac Phase Shift suggested by the Aharonov-Bohm effect for relativistic matter beams
The phase shift due to the Sagnac Effect, for relativistic matter beams
counter-propagating in a rotating interferometer, is deduced on the bases of a
a formal analogy with the the Aharonov-Bohm effect. A procedure outlined by
Sakurai, in which non relativistic quantum mechanics and newtonian physics
appear together with some intrinsically relativistic elements, is generalized
to a fully relativistic context, using the Cattaneo's splitting technique. This
approach leads to an exact derivation, in a self-consistently relativistic way,
of the Sagnac effect. Sakurai's result is recovered in the first order
approximation.Comment: 18 pages, LaTeX, 2 EPS figures. To appear in General Relativity and
Gravitatio
The shallow boreholes at The AltotiBerina near fault Observatory (TABOO; northern Apennines of Italy)
Abstract. As part of an interdisciplinary research project, funded by the European Research Council and addressing the mechanics of weak faults, we drilled three 200–250 m-deep boreholes and installed an array of seismometers. The array augments TABOO (The AltotiBerina near fault ObservatOry), a scientific infrastructure managed by the Italian National Institute of Geophysics and Volcanology. The observatory, which consists of a geophysical network equipped with multi-sensor stations, is located in the northern Apennines (Italy) and monitors a large and active low-angle normal fault. The drilling operations started at the end of 2011 and were completed by July 2012. We instrumented the boreholes with three-component short-period (2 Hz) passive instruments at different depths. The seismometers are now fully operational and collecting waveforms characterised by a very high signal to noise ratio that is ideal for studying microearthquakes. The resulting increase in the detection capability of the seismic network will allow for a broader range of transients to be identified
Conservation laws for vacuum tetrad gravity
Ten conservation laws in useful polynomial form are derived from a Cartan
form and Exterior Differential System (EDS) for the tetrad equations of vacuum
relativity. The Noether construction of conservation laws for well posed EDS is
introduced first, and an illustration given, deriving 15 conservation laws of
the free field Maxwell Equations from symmetries of its EDS. The Maxwell EDS
and tetrad gravity EDS have parallel structures, with their numbers of
dependent variables, numbers of generating 2-forms and generating 3-forms, and
Cartan character tables all in the ratio of 1 to 4. They have 10 corresponding
symmetries with the same Lorentz algebra, and 10 corresponding conservation
laws.Comment: Final version with additional reference
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