12,754 research outputs found
The effective mass of atom-radiation field system and the cavity-field Wigner distribution in the presence of a homogeneous gravitational field in the Jaynes-Cummings model
The effective mass that approximately describes the effect of a classical
homogeneous gravitational field on an interacting atom-radiation field system
is determined within the framework of the Jaynes-Cummings model.
By taking into account both the atomic motion and gravitational field, a full
quantum treatment of the internal and external dynamics of the atom is
presented. By solving exactly the Schrodinger equation in the interaction
picture, the evolving state of the system is found. Influence of a classical
homogeneous gravitational field on the energy eigenvalues, the effective mass
of atom-radiation field system and the Wigner distribution of the radiation
field are studied, when initially the radiation field is prepared in a coherent
state and the two-level atom is in a coherent superposition of the excited and
ground states.Comment: 12 pages, 9 figure
The effect of spin-orbit interaction on entanglement of two-qubit Heisenberg XYZ systems in an inhomogeneous magnetic field
The role of spin-orbit interaction on the ground state and thermal
entanglement of a Heisenberg XYZ two-qubit system in the presence of an
inhomogeneous magnetic field is investigated. For a certain value of spin-orbit
parameter , the ground state entanglement tends to vanish suddenly and when
crosses its critical value , the entanglement undergoes a revival. The
maximum value of the entanglement occurs in the revival region. In finite
temperatures there are revival regions in plane. In these regions,
entanglement first increases with increasing temperature and then decreases and
ultimately vanishes for temperatures above a critical value. This critical
temperature is an increasing function of , thus the nonzero entanglement can
exist for larger temperatures. In addition, the amount of entanglement in the
revival region depends on the spin-orbit parameter. Also, the entanglement
teleportation via the quantum channel constructed by the above system is
investigated and finally the influence of the spin-orbit interaction on the
fidelity of teleportation and entanglement of replica state is studied.Comment: Two columns, 9 pages, 8 Fig
Comparison of working memory, divided and selective attention in children with different types of attention deficit hyperactivity disorder- ADHD
Introduction: Attention Deficit and Hyperactivity are among the most common behavioral disorders in children which include three subgroups including inattention, hyperactivity - impulsivity (disinhibition) and mixed form. Attention Deficit and Hyperactivity Disorder might be along with basic symptoms in memory and attention and Working memory and various forms of selective and divided attention are compared in this study in hyperactive children and children with attention deficit.Method: in this study, 40 hyperactive children and children with attention deficit who have referred to children's psychiatric and occupational therapy centers in Tehran in 2016 have been selected as sample using stratified random sampling. This was a descriptive-analytic study. Data were collected using Kim Karad’s working memory test and Stroop’s selective and divided attention test. Obtained data were analyzed using SPSS software.Findings: findings showed significant difference between average working memory of three groups of children with attention deficit, hyperactivity and mixed form.  In this way that working memory in mixed form group had the weakest average, attention deficit had moderate average and hyperactive had the highest average. Comparison of selective and divided attention also indicated a significant difference between groups. In this way that, selective attention of children with mixed form with the least of all and it was the highest of all in hyperactive children. Divided attention or attention management was also the weakest in mixed form group and it had a higher average than the rest in hyperactive type.Discussion and conclusion: based on objectives and method of the research which was comparative, findings showed that active visual memory was more damaged in children with mixed form compare to two types of hyperactive children or children attention deficit. Also, findings related to comparison of selective and divided attention showed that selective and divided attention was lower in hyperactive children with mixed attention deficit compared to hyperactive children and was lower than attention deficit type in the next level.Keywords: selective attention, divided attention, hyperactive, attention deficit, mixe
The Occurrence of Type I, II, and III Integrons in Multi-drug Resistance and Methicillin-Resistant Staphylococcus aureus Isolates in Iran
Integrons are mobilizable platforms-DNA elements with impacts on moving antibiotic resistance genes among bacteria and capable of spreading multi-drug resistance (MDR) in pathogens. Methicillin-resistant Staphylococcus aureus (MRSA) strains are the main cause of community-acquired and nosocomial infections with high mortality and morbidity rates worldwide. This work is mainly aimed at calculating the frequency of Type I, II, and III integrons within multi-drug resistance and Methicillin-resistant S. aureus Isolates in Iran. In this cross-sectional study, 230 clinical isolates of S. aureus were gathered from patients of educational hospitals in the provinces of Iran. These isolates were verified utilizing particular biochemical examinations and then assessed for antibiotic susceptibility through disk diffusion technique and standard procedures were done. Genomic and plasmid DNA of all isolates were extracted using Extraction Kit and PCR assay was used for the detection of Type I, II and III integrons genes. Out of the 230 S. aureus isolates, 136 (59.1) isolates were MRSA and 141 (61.3) isolates exhibited the MDR pattern. PCR and sequencing showed that 57 (24.8) of tested isolates carry Type I integron. Among the isolates investigated, MRSA and MDR isolates showed frequencies of 56.1 and 57.9, respectively. Type II and III integrons were found in none of 230 isolates. The IntI I gene was present in approximately one-quarter of this study isolates. The great prevalence rate of MDR and MRSA isolates and concurrently the existence of Type I integron among those isolates have been considered an important concern in medical society. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
COVID-19 publications: Database coverage, citations, readers, tweets, news, Facebook walls, Reddit posts
© 2020 The Authors. Published by MIT Press. This is an open access article available under a Creative Commons licence.
The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1162/qss_a_00066The COVID-19 pandemic requires a fast response from researchers to help address biological,
medical and public health issues to minimize its impact. In this rapidly evolving context,
scholars, professionals and the public may need to quickly identify important new studies. In
response, this paper assesses the coverage of scholarly databases and impact indicators
during 21 March to 18 April 2020. The rapidly increasing volume of research, is particularly
accessible through Dimensions, and less through Scopus, the Web of Science, and PubMed.
Google Scholar’s results included many false matches. A few COVID-19 papers from the
21,395 in Dimensions were already highly cited, with substantial news and social media
attention. For this topic, in contrast to previous studies, there seems to be a high degree of
convergence between articles shared in the social web and citation counts, at least in the
short term. In particular, articles that are extensively tweeted on the day first indexed are
likely to be highly read and relatively highly cited three weeks later. Researchers needing wide
scope literature searches (rather than health focused PubMed or medRxiv searches) should
start with Dimensions (or Google Scholar) and can use tweet and Mendeley reader counts as
indicators of likely importance
Lorentz-violating dimension-five operator contribution to the black body radiation
We investigate the thermodynamics of a photon gas in an effective field
theory model that describes Lorentz violations through dimension-five operators
and Horava-Lifshitz theory. We explore the electrodynamics of the model which
includes higher order derivatives in the Lagrangian that can modify the
dispersion relation for the propagation of the photons. We shall focus on the
deformed black body radiation spectrum and modified Stefan-Boltzmann law to
address the allowed bounds on the Lorentz-violating parameter.Comment: 8 pages, 6 figures. Version published in PL
Thermodynamics of Taub-NUT/Bolt-AdS Black Holes in Einstein-Gauss-Bonnet Gravity
We give a review of the existence of Taub-NUT/bolt solutions in Einstein
Gauss-Bonnet gravity with the parameter in six dimensions. Although
the spacetime with base space has curvature singularity at
, which does not admit NUT solutions, we may proceed with the same
computations as in the case. The investigation of
thermodynamics of NUT/Bolt solutions in six dimensions is carried out. We
compute the finite action, mass, entropy, and temperature of the black hole.
Then the validity of the first law of thermodynamics is demonstrated. It is
shown that in NUT solutions all thermodynamic quantities for both base spaces
are related to each other by substituting
. So no further information is given by investigating NUT
solution in the case. This relation is not true for bolt
solutions. A generalization of the thermodynamics of black holes to arbitrary
even dimensions is made using a new method based on the Gibbs-Duhem relation
and Gibbs free energy for NUT solutions. According to this method, the finite
action in Einstein Gauss-Bonnet is obtained by considering the generalized
finite action in Einstein gravity with an additional term as a function of
. Stability analysis is done by investigating the heat capacity and
entropy in the allowed range of , and . For NUT solutions
in dimensions, there exist a stable phase at a narrow range of . In
six-dimensional Bolt solutions, metric is completely stable for
, and is completely unstable for
case.Comment: 19 pages, 3 figures, some Refs. are added, Fig 1 is replaced, and
some corrections are don
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