497 research outputs found
Detectability of dissipative motion in quantum vacuum via superradiance
We propose an experiment for generating and detecting vacuum-induced
dissipative motion. A high frequency mechanical resonator driven in resonance
is expected to dissipate energy in quantum vacuum via photon emission. The
photons are stored in a high quality electromagnetic cavity and detected
through their interaction with ultracold alkali-metal atoms prepared in an
inverted population of hyperfine states. Superradiant amplification of the
generated photons results in a detectable radio-frequency signal temporally
distinguishable from the expected background.Comment: 4 pages, 2 figure
Casimir force between eccentric cylinders
We consider the Casimir interaction between a cylinder and a hollow cylinder,
both conducting, with parallel axis and slightly different radii. The Casimir
force, which vanishes in the coaxial situation, is evaluated for both small and
large eccentricities using the proximity approximation. The cylindrical
configuration offers various experimental advantages with respect to the
parallel planes or the plane-sphere geometries, leading to favourable
conditions for the search of extra-gravitational forces in the micrometer range
and for the observation of finite temperature corrections.Comment: To be published in Europhysics Letters. 7 pages, 4 figure
Measurement-induced Squeezing of a Bose-Einstein Condensate
We discuss the dynamics of a Bose-Einstein condensate during its
nondestructive imaging. A generalized Lindblad superoperator in the condensate
master equation is used to include the effect of the measurement. A continuous
imaging with a sufficiently high laser intensity progressively drives the
quantum state of the condensate into number squeezed states. Observable
consequences of such a measurement-induced squeezing are discussed.Comment: 4 pages, 2 figures, submitted to PR
El rol del oficial de cumplimiento y los programas de integridad en las organizaciones
This article aims at reviewing the results of a survey carried out in the second semester of 2019 as part of the Strategic Development Project (PDE) of the University of Buenos Aires PDE_9_2019 âCorruption, business fraud and compliance systems in organizationsâ.
The questions are addressed to internal participants, regardless of their role within the organization. The purpose of this survey is to determine the importance attached to compliance systems by organizations.
Seventy answers were considered. Although the results are not categorical, we can observe that the Compliance figure holds an adequate hierarchical position, which should provide it with independence and resources within the structure. However, further progress needs to be made in relation to training and education on key elements of the integrity program, considered necessary under the terms of Law No. 27,401.El presente trabajo tiene por fin revisar los resultados de una encuesta realizada en el segundo semestre del año 2019, en el marco del proyecto de Desarrollo EstrateÌgico (PDE) de la Universidad de Buenos Aires PDE_9_2019 âCorrupciĂłn, fraude empresario y sistemas de cumplimiento en las organizacionesâ.
Las preguntas estĂĄn dirigidas a los participantes internos cualquiera sea el rol que ocupan dentro de la organizaciĂłn. El objetivo de esta encuesta es poder determinar la importancia que las organizaciones le dan a los sistemas de Compliance.
Las respuestas consideradas fueron 70. Si bien los resultados no son categĂłricos podemos observar que la figura del Compliance ocupa un posicionamiento jerĂĄrquico adecuado lo que deberĂa darle independencia y recursos dentro de la estructura. Sin embargo, aĂșn queda un camino por recorrer en relaciĂłn con las capacitaciones y entrenamiento acerca de elementos claves del programa de integridad, consideradas necesarias de acuerdo con los tĂ©rminos de la Ley 27.401
Black hole mass estimates in quasars - A comparative analysis of high- and low-ionization lines
The inter-line comparison between high- and low-ionization emission lines has
yielded a wealth of information on the quasar broad line region (BLR) structure
and dynamics, including perhaps the earliest unambiguous evidence in favor of a
disk + wind structure in radio-quiet quasars. We carried out an analysis of the
CIV 1549 and Hbeta line profiles of 28 Hamburg-ESO high luminosity quasars and
of 48 low-z, low luminosity sources in order to test whether the
high-ionization line CIV 1549 width could be correlated with Hbeta and be used
as a virial broadening estimator. We analyze intermediate- to high-S/N,
moderate resolution optical and NIR spectra covering the redshifted CIV and
H over a broad range of luminosity log L ~ 44 - 48.5 [erg/s] and
redshift (0 - 3), following an approach based on the quasar main sequence. The
present analysis indicates that the line width of CIV 1549 is not immediately
offering a virial broadening estimator equivalent to H. At the same time
a virialized part of the BLR appears to be preserved even at the highest
luminosities. We suggest a correction to FWHM(CIV) for Eddington ratio (using
the CIV blueshift as a proxy) and luminosity effects that can be applied over
more than four dex in luminosity. Great care should be used in estimating
high-L black hole masses from CIV 1549 line width. However, once corrected
FWHM(CIV) values are used, a CIV-based scaling law can yield unbiased MBH
values with respect to the ones based on H with sample standard
deviation ~ 0.3 dex.Comment: 43 pages, 15 Figures, submitted to A&
Exact Casimir interaction between eccentric cylinders
The Casimir force is the ultimate background in ongoing searches of
extra-gravitational forces in the micrometer range. Eccentric cylinders offer
favorable experimental conditions for such measurements as spurious
gravitational and electrostatic effects can be minimized. Here we report on the
evaluation of the exact Casimir interaction between perfectly conducting
eccentric cylinders using a mode summation technique, and study different
limiting cases of relevance for Casimir force measurements, with potential
implications for the understanding of mechanical properties of nanotubes.Comment: 5 pages, 4 figure
Thermal and dissipative effects in Casimir physics
We report on current efforts to detect the thermal and dissipative
contributions to the Casimir force. For the thermal component, two experiments
are in progress at Dartmouth and at the Institute Laue Langevin in Grenoble.
The first experiment will seek to detect the Casimir force at the largest
explorable distance using a cylinder-plane geometry which offers various
advantages with respect to both sphere-plane and parallel-plane geometries. In
the second experiment, the Casimir force in the parallel-plane configuration is
measured with a dedicated torsional balance, up to 10 micrometers. Parallelism
of large surfaces, critical in this configuration, is maintained through the
use of inclinometer technology already implemented at Grenoble for the study of
gravitationally bound states of ultracold neutrons, For the dissipative
component of the Casimir force, we discuss detection techniques based upon the
use of hyperfine spectroscopy of ultracold atoms and Rydberg atoms. Although
quite challenging, this triad of experimental efforts, if successful, will give
us a better knowledge of the interplay between quantum and thermal fluctuations
of the electromagnetic field and of the nature of dissipation induced by the
motion of objects in a quantum vacuum.Comment: Contribution to QFEXT'06, appeared in special issue of Journal of
Physics
Gestures and words in naming: Evidence from cross-linguistic and cross-cultural comparison
We report on an analysis of spontaneous gesture production in 2-year-old children who come from three countries (Italy, UK and Australia) and whom speak two languages (Italian and English), in an attempt to tease apart the influence of language and culture when comparing children from different cultural and linguistic environments. Eighty-seven monolingual children aged 24-30 months completed an experimental task measuring their comprehension and production of nouns and predicates. The Italian children scored significantly higher than the other groups on all lexical measures. With regards to gestures, British children produced significantly fewer pointing and speech combinations compared to the Italian and Australian children, who did not differ from each other. In contrast, Italian children produced significantly more representational gestures than the two other groups. We conclude that spoken language development is primarily influenced by the input language over gesture production, whereas the combination of cultural and language environments affects gesture productions
Anomalies in electrostatic calibrations for the measurement of the Casimir force in a sphere-plane geometry
We have performed precision electrostatic calibrations in the sphere-plane
geometry and observed anomalous behavior. Namely, the scaling exponent of the
electrostatic signal with distance was found to be smaller than expected on the
basis of the pure Coulombian contribution and the residual potential found to
be distance dependent. We argue that these findings affect the accuracy of the
electrostatic calibrations and invite reanalysis of previous determinations of
the Casimir force.Comment: 4 pages, 4 figure
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