1,656 research outputs found
Entanglement properties in the Inhomogeneous Tavis-Cummings model
In this work we study the properties of the atomic entanglement in the
eigenstates spectrum of the inhomogeneous Tavis-Cummings Model. The
inhomogeneity is present in the coupling among the atoms with quantum
electromagnetic field. We calculate analytical expressions for the concurrence
and we found that this exhibits a strong dependence on the inhomogeneity.Comment: 5 pages, 5 figure
On the origin of the jet-like radio/X-ray morphology of G290.1-0.8
The origin and evolution of supernova remnants of the mixed-morphology class
is not well understood. Several remnants present distorted radio or X-ray
shells with jet-like structures. G290.1-0.8 (MSH 11-61A) belongs to this class.
We aim to investigate the nature of this supernova remnant in order to unveil
the origin of its particular morphology. We based our work on the study of the
X-ray emitting plasma properties and the conditions imposed by the cold
interstellar medium where the remnant expanded. We use archival radio, HI line
data and X-ray observations from XMM-Newton and Chandra observatories, to study
G290.1-0.8 and its surrounding medium. Spatially resolved spectral analysis and
mean photon energy maps are used to obtain physical and geometrical parameters
of the source. Radio continuum and HI line maps give crucial information to
understand the radio/X-ray morphology. The X-ray images show that the remnant
presents two opposite symmetric bright spots on a symmetry axis running towards
the NW-SE direction. Spectral analysis and mean photon energy maps confirm that
the physical conditions of the emitting plasma are not homogeneous throughout
the remnant. In fact, both bright spots have higher temperatures than the rest
of the plasma and its constituents have not reached ionization equilibrium yet.
HI line data reveal low density tube-like structures aligned along the same
direction. This evidence supports the idea that the particular X-ray morphology
observed is a direct consequence of the structure of the interstellar medium
where the remnant evolved. However, the possibility that an undetected
point-like object, as a neutron star, exists within the remnant and contributes
to the X-ray emission cannot be discarded. Finally, we suggest that a supernova
explosion due to the collapse of a high-mass star with a strong bipolar wind
can explain the supernova remnant morphology.Comment: 8 pages, 6 figures. Accepted for publication in A&
Abrupt Changes in the Dynamics of Quantum Disentanglement
Entanglement evolution in high dimensional bipartite systems under
dissipation is studied. Discontinuities for the time derivative of the lower
bound of entanglement of formation is found depending on the initial conditions
for entangled states. This abrupt changes along the evolution appears as
precursors of entanglement sudden death.Comment: 4 pages and 6 figures, submitted for publicatio
Plateau insulator transition in graphene
The quantum Hall effect in a single-layer graphene sample is studied in
strong magnetic fields up to 28 T. Our measurements reveal the existence of a
metal- insulator transition from filling factor to . The value
of the universal scaling exponent is found to be in graphene and
therefore in a truly two-dimensional system. This value of is in
agreement with the accepted universal value for the plateau-insulator
transitions in standard quasi two-dimensional electron and hole gases.Comment: 10 pages, 5 figure
Preliminary results of the effect of temperature and relative humidity on milk yield and components in Payoya breed goats
Un total de 81625 registros mensuales de 8380 hembras de la raza Payoya paridas en 18 ganaderías
entre 2004 y 2007 fueron estudiados aplicando diferentes modelos lineales, con el objetivo de estimar
los posibles efectos de un índice que combina Temperatura y Humedad Relativa (THI), sobre las variables
de producción de leche y sus características físico-químicas. Los primeros resultados indicaron que
existe una zona de termoneutralidad (THI entre 13 y 22) en la cual no se han evidenciado claramente
los efectos del estrés térmico. Para valores de THI>22 se creó una función fT para estimar los componentes
genéticos generales y los debidos al estrés térmico. Las correlaciones genéticas fueron -0.342 y
-0.320 entre producción de leche y la fT indicando un antagonismo entre ambas características. Por
último, se pudo poner de manifiesto la existencia de una variabilidad genética importante para capacidad
de adaptación frente al estrés térmico. Estos resultados pueden brindar importantes beneficios
a los criadores de la raza caprina PayoyaProduction data included 81625 test-day records of 8380 dairy goats (Payoya breed) from 18 flocks
collected from 2004 to 2007. The traits analyzed were daily milk yield and milk composition, using
different linear models, to determine the effect of increasing temperature-humidity index (THI) on
these traits. The results report that the range between 13 and 22 for THI is the thermoneutral zone
of the animals. The genetic correlations between the general additive effect and the additive effect
of heat tolerance were negative (-0,342 to -0,320) to THI>22. Therefore, milk yield is antagonistic
with heat tolerance. However, the genetic variability to heat tolerance could report important profits
to dairy goat breeders if they consider the greater or smaller adaptability to the environmental
conditions as a selection criteri
Rise and fall of †Pycnodontiformes: Diversity, competition and extinction of a successful fish clade
Singlet channel scattering in a composite Higgs model on the lattice
AbstractWe present the first calculation of the scattering amplitude in the singlet channel beyond QCD. The calculation is performed in SU(2) gauge theory with N f = 2 fundamental Dirac fermions and based on a finite-volume scattering formalism. The theory exhibits a S U ( 4 ) → S p ( 4 ) chiral symmetry breaking pattern that is used to design minimal composite Higgs models currently tested at the LHC. Our results show that, for the range of underlying fermion mass considered, the lowest flavour singlet state is stable.</jats:p
The ALMA Frontier Fields Survey - IV. Lensing-corrected 1.1 mm number counts in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223
[abridged] Characterizing the number counts of faint, dusty star-forming
galaxies is currently a challenge even for deep, high-resolution observations
in the FIR-to-mm regime. They are predicted to account for approximately half
of the total extragalactic background light at those wavelengths. Searching for
dusty star-forming galaxies behind massive galaxy clusters benefits from strong
lensing, enhancing their measured emission while increasing spatial resolution.
Derived number counts depend, however, on mass reconstruction models that
properly constrain these clusters. We estimate the 1.1 mm number counts along
the line of sight of three galaxy clusters, i.e. Abell 2744, MACSJ0416.1-2403
and MACSJ1149.5+2223, which are part of the ALMA Frontier Fields Survey. We
perform detailed simulations to correct these counts for lensing effects. We
use several publicly available lensing models for the galaxy clusters to derive
the intrinsic flux densities of our sources. We perform Monte Carlo simulations
of the number counts for a detailed treatment of the uncertainties in the
magnifications and adopted source redshifts. We find an overall agreement among
the number counts derived for the different lens models, despite their
systematic variations regarding source magnifications and effective areas. Our
number counts span ~2.5 dex in demagnified flux density, from several mJy down
to tens of uJy. Our number counts are consistent with recent estimates from
deep ALMA observations at a 3 level. Below 0.1 mJy, however,
our cumulative counts are lower by 1 dex, suggesting a flattening in
the number counts. In our deepest ALMA mosaic, we estimate number counts for
intrinsic flux densities 4 times fainter than the rms level. This
highlights the potential of probing the sub-10 uJy population in larger samples
of galaxy cluster fields with deeper ALMA observations.Comment: 19 pages, 14 figures, 3 tables. Accepted for publication in A&
Calculation of kinetic parameters βeff and Λ with modified open source Monte Carlo code OpenMC(TD)
This work presents the methodology used to expand the capabilities of the Monte Carlo code OpenMC for the calculation of reactor kinetic parameters: effective delayed neutron fraction βeff and neutron generation time Λ. The modified code, OpenMC(Time-Dependent) or OpenMC(TD), was then used to calculate the effective delayed neutron fraction by using the prompt method, while the neutron generation time was estimated using the pulsed method, fitting Λ to the decay of the neutron population. OpenMC(TD) is intended to serve as an alternative for the estimation of kinetic parameters when licensed codes are not available. The results obtained are compared to experimental data and MCNP calculated values for 18 benchmark configurations.Fil: Romero Barrientos, J.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; ChileFil: Marquez Damian, Jose Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. European Spallation Source; SueciaFil: Molina, F.. Comision Chilena de Energia Nuclear; Chile. Universidad Andrés Bello; ChileFil: Zambra, M.. Comision Chilena de Energia Nuclear; Chile. Universidad Diego Portales; ChileFil: Aguilera, P.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; ChileFil: López Usquiano, F.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; ChileFil: Parra, B.. Instituto de Física Corpuscular; EspañaFil: Ruiz, A.. Comision Chilena de Energia Nuclear; Chile. Universidad de Chile; Chil
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