141 research outputs found
Nonclassical statistics of intracavity coupled waveguides: the quantum optical dimer
A model is proposed where two nonlinear waveguides are contained
in a cavity suited for second-harmonic generation. The evanescent wave coupling
between the waveguides is considered as weak, and the interplay between this
coupling and the nonlinear interaction within the waveguides gives rise to
quantum violations of the classical limit. These violations are particularly
strong when two instabilities are competing, where twin-beam behavior is found
as almost complete noise suppression in the difference of the fundamental
intensities. Moreover, close to bistable transitions perfect twin-beam
correlations are seen in the sum of the fundamental intensities, and also the
self-pulsing instability as well as the transition from symmetric to asymmetric
states display nonclassical twin-beam correlations of both fundamental and
second-harmonic intensities. The results are based on the full quantum Langevin
equations derived from the Hamiltonian and including cavity damping effects.
The intensity correlations of the output fields are calculated
semi-analytically using a linearized version of the Langevin equations derived
through the positive-P representation. Confirmation of the analytical results
are obtained by numerical simulations of the nonlinear Langevin equations
derived using the truncated Wigner representation.Comment: 15 pages, 8 figures, submitted to Phys. Rev.
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A randomised controlled trial of treatments of childhood anxiety disorder in the context of maternal anxiety disorder: clinical and cost-effectiveness outcomes
Background: This study evaluated whether clinical and economic outcomes from CBT for child anxiety disorders in the context of maternal anxiety disorders are improved by adding treatment focused on (i) maternal anxiety disorders, or (ii) mother-child interactions. Methods: 211 children (7 â 12 years, 85% White British, 52% female) with a primary anxiety disorder, whose mothers also had a current anxiety disorder, were randomised to receive (i) child-focused CBT with non-specific control interventions (CCBT+Con), (ii) CCBT with CBT for the maternal anxiety disorder (CCBT+MCBT), or (iii) CCBT with an intervention targeting the mother-child interaction (CCBT+MCI). A cost-utility analysis from a societal perspective was conducted using mother/child combined Quality Adjusted Life Years (QALYs). [Trial registration: https://doi.org/10.1186/ISRCTN19762288]. Results: MCBT was associated with immediate reductions in maternal anxiety compared to the non-specific control; however, after children had also received CCBT, maternal outcomes in the CCBT+MCI and CCBT+Con arms improved and CCBT+MCBT was no longer superior. Neither CCBT+MCBT nor CCBT+MCI conferred a benefit over CCBT+Con in terms of child anxiety disorder diagnoses post-treatment [primary outcome] (adj RR: 1.22 (95% CI 0.88, 1.67), p = .23; adj RR: 1.21 (95% CI 0.88, 1.65), p = .24 respectively) or global improvement ratings (adj RR 1.25 (95% CI 0.99, 1.57), p = .06; adj RR 1.18 (95% CI 0.93, 1.50), p = .17) or six and 12 months later. No significant differences between the groups were found on the main economic outcome measures (child/mother combined QALY mean difference: CCBT+MCBT vs CCBT+Con: -0.04 (95% CI -0.12, 0.04), p = 0.29; CCBT+MCI vs CCBT+Con: 0.02 (95% CI -0.05, -0.09), p = 0.54). CCBT+MCI was associated with non-significantly higher costs than CCBT (mean difference: ÂŁ154 (95% CI -ÂŁ1239, ÂŁ1547), p = 0.83) but, when taking into account sampling uncertainty, it may be cost-effective compared with CCBT alone. Conclusions: Good outcomes were achieved for children and their mothers across treatment arms. There was no evidence of significant clinical benefit from supplementing CCBT with either CBT for the maternal anxiety disorder or treatment focussed on mother-child interactions, but the addition of MCI (and not MCBT) may be cost-effective. Keywords: Child; anxiety; mother; parent-child interaction; CBT
Adiabatic Elimination in Compound Quantum Systems with Feedback
Feedback in compound quantum systems is effected by using the output from one
sub-system (``the system'') to control the evolution of a second sub-system
(``the ancilla'') which is reversibly coupled to the system. In the limit where
the ancilla responds to fluctuations on a much shorter time scale than does the
system, we show that it can be adiabatically eliminated, yielding a master
equation for the system alone. This is very significant as it decreases the
necessary basis size for numerical simulation and allows the effect of the
ancilla to be understood more easily. We consider two types of ancilla: a
two-level ancilla (e.g. a two-level atom) and an infinite-level ancilla (e.g.
an optical mode). For each, we consider two forms of feedback: coherent (for
which a quantum mechanical description of the feedback loop is required) and
incoherent (for which a classical description is sufficient). We test the
master equations we obtain using numerical simulation of the full dynamics of
the compound system. For the system (a parametric oscillator) and feedback
(intensity-dependent detuning) we choose, good agreement is found in the limit
of heavy damping of the ancilla. We discuss the relation of our work to
previous work on feedback in compound quantum systems, and also to previous
work on adiabatic elimination in general.Comment: 18 pages, 12 figures including two subplots as jpeg attachment
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Gradient models of the axion-photon coupling
We establish an extended version of the Einstein - Maxwell - axion model by
introducing into the Lagrangian cross-terms, which contain the gradient
four-vector of the pseudoscalar (axion) field in convolution with the Maxwell
tensor. The gradient model of the axion-photon coupling is applied to
cosmology: we analyze the Bianchi-I type Universe with an initial magnetic
field, electric field induced by the axion-photon interaction, cosmological
constant and dark matter, which is described in terms of the pseudoscalar
(axion) field. Analytical, qualitative and numerical results are presented in
detail for two distinguished epochs: first, for the early Universe with
magnetic field domination; second, for the stage of late-time accelerated
expansion.Comment: 26 pages, 5 figures, accepted for publication in The European
Physical Journal
Should science educators deal with the science/religion issue?
I begin by examining the natures of science and religion before looking at the ways in which they relate to one another. I then look at a number of case studies that centre on the relationships between science and religion, including attempts to find mechanisms for divine action in quantum theory and chaos theory, creationism, genetic engineering and the writings of Richard Dawkins. Finally, I consider some of the pedagogical issues that would need to be considered if the science/religion issue is to be addressed in the classroom. I conclude that there are increasing arguments in favour of science educators teaching about the science/religion issue. The principal reason for this is to help students better to learn science. However, such teaching makes greater demands on science educators than has generally been the case. Certain of these demands are identified and some specific suggestions are made as to how a science educator might deal with the science/religion issue. © 2008 Taylor & Francis
PteridĂłfitas da Serra Negra, Minas Gerais, Brasil
Este trabalho apresenta uma lista de espĂ©cies de pteridĂłfitas que ocorrem na Serra Negra, Minas Gerais. A serra estĂĄ inserida no complexo da Serra da Mantiqueira situada entre Rio Preto, Lima Duarte, Santa BĂĄrbara do Monte Verde e Olaria, tendo seus limites nos pontos 21Âș58'11"S 43Âș53'21" W, 22Âș01'46,4" S 43Âș52'31,5" W, 21Âș58'21,4" S 43Âș50'06,5" W e 21Âș58'53" S 43Âș56'08" W. A vegetação da serra Ă© formada por um mosaico de fitofisionomias, sendo encontradas formaçÔes florestais (florestas ombrĂłfilas e semidecĂduas) e campestres (campos rupestres). O inventĂĄrio florĂstico foi realizado entre os anos de 2003 e 2008, em excursĂ”es mensais para coleta de amostras e registro de dados. Na serra foram registradas 209 tĂĄxons infragenĂ©ricos distribuĂdas em 24 famĂlias e 75 gĂȘneros. As famĂlias com maior nĂșmero de espĂ©cies foram Polypodiaceae (40), Dryopteridaceae (33) e Pteridaceae (25). A maioria das espĂ©cies (109) foi encontrada ocorrendo exclusivamente no interior de floresta. Em relação ao hĂĄbito, 69 espĂ©cies foram encontradas exclusivamente como terrestres, 37 como rupĂcolas ou terrestres e 32 exclusivamente epĂfitas. Este trabalho revela uma elevada riqueza de pteridĂłfitas na regiĂŁo e indica a importĂąncia de estudos desta natureza na conservação e manejo das pteridĂłfitas em Minas Gerais.This work presents an inventory of pteridophyte species that occur in the Serra Negra, of Minas Gerais. The area is part of the Mantiqueira Range, and is situated between the coordinates 21Âș58'11"S 43Âș53'21" W, 22Âș01'4.4" S, 43Âș52'31.5" W, 21Âș58'21.4" S, 43Âș50'06.5" W and 21Âș58'53" S, 43Âș56'08" W. The vegetation in the Serra Negra is characterized by a mosaic of different phytophysiognomies, divided into forests (evergreen and seasonal semideciduous forests) and open formations (rocky grasslands). The inventory was carried out from 2003 to 2008, during monthly excursions to collect botanical material and data in the study area. A total of 209 species, distributed in 24 families and 75 genera, were recorded. The families with the highest number of species were Polypodiaceae (40), Dryopteridaceae (33) and Pteridaceae (25). More than the half (110) of the inventoried species were recorded exclusively in the forests formations. Sixty-nine species were terrestrial, 37 were saxicolous or terrestrial and 32 were epiphytes. This work shows that this region is rich in ferns and reveals the importance of this kind of study for conservation and management of pteridophytes in the state of Minas Gerais
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