2,454 research outputs found
Geometric Phase of a qubit interacting with a squeezed-thermal bath
We study the geometric phase of an open two-level quantum system under the
influence of a squeezed, thermal environment for both non-dissipative as well
as dissipative system-environment interactions. In the non-dissipative case,
squeezing is found to have a similar influence as temperature, of suppressing
geometric phase, while in the dissipative case, squeezing tends to counteract
the suppressive influence of temperature in certain regimes. Thus, an
interesting feature that emerges from our work is the contrast in the interplay
between squeezing and thermal effects in non-dissipative and dissipative
interactions. This can be useful for the practical implementation of geometric
quantum information processing. By interpreting the open quantum effects as
noisy channels, we make the connection between geometric phase and quantum
noise processes familiar from quantum information theory.Comment: Accepted for publication in Eur. Phys. J. D; slightly abridged
version of v2; 10 pages, 12 figure
A General Form of Covariate Adjustment in Randomized Clinical Trials
In randomized clinical trials, adjusting for baseline covariates has been
advocated as a way to improve credibility and efficiency for demonstrating and
quantifying treatment effects. This article studies the augmented inverse
propensity weighted (AIPW) estimator, which is a general form of covariate
adjustment that includes approaches using linear and generalized linear models
and machine learning models. Under covariate-adaptive randomization, we
establish a general theorem that shows a complete picture about the asymptotic
normality, efficiency gain, and applicability of AIPW estimators. Based on the
general theorem, we provide insights on the conditions for guaranteed
efficiency gain and universal applicability under different randomization
schemes, which also motivate a joint calibration strategy using some
constructed covariates after applying AIPW. We illustrate the application of
the general theorem with two examples, the generalized linear model and the
machine learning model. We provide the first theoretical justification of using
machine learning methods with dependent data under covariate-adaptive
randomization. Our methods are implemented in the R package RobinCar
Logarithmic corrections to black hole and black ring entropy in tunneling approach
The tunneling approach beyond semiclassical approximation has been used to
calculate the corrected Hawking temperature and entropy for various black holes
and FRW universe model. We examine their derivations, and prove that the
quantity in the corrected temperature is the explicit function of the only
free parameter (which is an auxiliary parameter defined by
). Our analysis improves previous calculations, and
indicates that the leading order logarithmic correction to entropy is a natural
result of the corrected temperature and the first law of thermodynamics.
Additionally, we apply the tunneling approach beyond semiclassical
approximation to neutral black rings. Based on the analysis, we show that the
entropy of neutral black rings also has a logarithmic leading order correction.Comment: 13 pages, rewritte
An Investigation of Hadronization Mechanism at Factory
We briefly review the hadronization pictures adopted in the LUND String
Fragmentation Model(LSFM), Webber Cluster Fragmentation Model(WCFM) and Quark
Combination Model(QCM), respectively. Predictions of hadron multiplicity,
baryon to meson ratios and baryon-antibaryon flavor correlations, especially
related to heavy hadrons at factory obtained by LSFM and QCM are
reported.Comment: 18 pages, 6 figures. accepted by Sci China Phys Mech Astro
Defects, band bending and ionization rings in MoS2
Chalcogen vacancies in transition metal dichalcogenides are widely
acknowledged as both donor dopants and as a source of disorder. The electronic
structure of sulphur vacancies in MoS2 however is still controversial, with
discrepancies in the literature pertaining to the origin of the in-gap features
observed via scanning tunneling spectroscopy (STS) on single sulphur vacancies.
Here we use a combination of scanning tunnelling microscopy (STM) and STS to
study embedded sulphur vacancies in bulk MoS2 crystals. We observe
spectroscopic features dispersing in real space and in energy, which we
interpret as tip position- and bias-dependent ionization of the sulphur vacancy
donor due to tip induced band bending (TIBB). The observations indicate that
care must be taken in interpreting defect spectra as reflecting in-gap density
of states, and may explain discrepancies in the literature.Comment: 7 pages, 5 figure
Thermal Unparticles: A New Form of Energy Density in the Universe
Unparticle \U with scaling dimension d_\U has peculiar thermal properties
due to its unique phase space structure. We find that the equation of state
parameter \omega_\U, the ratio of pressure to energy density, is given by
1/(2d_\U +1) providing a new form of energy in our universe. In an expanding
universe, the unparticle energy density \rho_\U(T) evolves dramatically
differently from that for photons. For d_\U >1, even if \rho_\U(T_D) at a
high decoupling temperature is very small, it is possible to have a large
relic density \rho_\U(T^0_\gamma) at present photon temperature ,
large enough to play the role of dark matter. We calculate and
\rho_\U(T^0_\gamma) using photon-unparticle interactions for illustration.Comment: 5 pages; v3, journal version
Examine the species and beam-energy dependence of particle spectra using Tsallis Statistics
Tsallis Statistics was used to investigate the non-Boltzmann distribution of
particle spectra and their dependence on particle species and beam energy in
the relativistic heavy-ion collisions at SPS and RHIC. Produced particles are
assumed to acquire radial flow and be of non-extensive statistics at
freeze-out. J/psi and the particles containing strangeness were examined
separately to study their radial flow and freeze-out. We found that the strange
hadrons approach equilibrium quickly from peripheral to central A+A collisions
and they tend to decouple earlier from the system than the light hadrons but
with the same final radial flow. These results provide an alternative picture
of freeze-outs: a thermalized system is produced at partonic phase; the
hadronic scattering at later stage is not enough to maintain the system in
equilibrium and does not increase the radial flow of the copiously produced
light hadrons. The J/psi in Pb+Pb collisions at SPS is consistent with early
decoupling and obtains little radial flow. The J/psi spectra at RHIC are also
inconsistent with the bulk flow profile.Comment: 12 pages, 4 figures, added several references and some clarifications
et
Giant Gravitons in type IIA PP-wave Background
We examine giant gravitons with a worldvolume magnetic flux in type IIA
pp-wave background and find that they can move away from the origin along
direction in target space satisfying . This nontrivial relation can be
regarded as a complementary relation of the giant graviton on IIA pp-wave and
is shown to be connected to the spacetime uncertainty principle. The giant
graviton is also investigated in a system of N D0-branes as a fuzzy sphere
solution. It is observed that enters into the fuzzy algebra as a
deformation parameter. Such a background dependent Myers effect guarantees that
we again get the crucial relation of our giant graviton. In the paper, we also
find a BIon configuration on the giant graviton in this background.Comment: 10 pages, no figure, content added, typo corrected, reference adde
The All-Data-Based Evolutionary Hypothesis of Ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata)
This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ The file attached is the published version of the article
Vision-related Quality of Life and Emotional Impact in Children with Strabismus: a Prospective Study
The potential impact of the surgical correction of strabismus on vision-related quality of life (VRQOL) and the symptoms of anxiety and depression in children with strabismus remain unclear. The present study included 60 children with strabismus: 30 with heterophoria and 30 with heterotropia. A healthy age- and gender-matched control group (n = 60) was also recruited. The psychological instruments that were used were the short-form 25-item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25) and the Hospital Anxiety and Depression Scale (HADS). The results demonstrated that eight of the 12 NEI-VFQ-25 subscales were significantly impaired in children with strabismus compared with matched controls. Compared with pre-operative values, significant improvements were noted after surgery in the NEI-VFQ-25 summary score, and the anxiety and depression scores. This study demonstrated that the NEI-VFQ-25 instrument can be used in strabismus children and that surgical interventions can improve VRQOL, anxiety and depression in strabismus patients
- …