3,317 research outputs found
Work relations for a system governed by Tsallis statistics
We derive analogues of the Jarzynski equality and Crooks relation to
characterise the nonequilibrium work associated with changes in the spring
constant of an overdamped oscillator in a quadratically varying spatial
temperature profile. The stationary state of such an oscillator is described by
Tsallis statistics, and the work relations for certain processes may be
expressed in terms of q-exponentials. We suggest that these identities might be
a feature of nonequilibrium processes in circumstances where Tsallis
distributions are found
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Coherence between subjective experience and physiology in emotion: Individual differences and implications for well-being.
Emotion theorists have characterized emotions as involving coherent responding across various emotion response systems (e.g., covariation of subjective experience and physiology). Greater response system coherence has been theorized to promote well-being, yet very little research has tested this assumption. The current study examined whether individuals with greater coherence between physiology and subjective experience of emotion report greater well-being. We also examined factors that may predict the magnitude of coherence, such as emotion intensity, cognitive reappraisal, and expressive suppression. Participants (N = 63) completed self-report measures of well-being, expressive suppression, and cognitive reappraisal. They then watched a series of emotionally evocative film clips designed to elicit positive and negative emotion. During the films, participants continuously rated their emotional experience using a rating dial, and their autonomic physiological responses were recorded. Time-lagged cross-correlations were used to calculate within-participant coherence between intensity of emotional experience (ranging from neutral to very negative or very positive) and physiology (composite of cardiac interbeat interval, skin conductance, ear pulse transit time, finger pulse transit time and amplitude, systolic and diastolic blood pressure). Results indicated that individuals with greater coherence reported greater well-being. Coherence was highest during the most emotionally intense film and among individuals who reported lower expressive suppression. However, coherence was not associated with reappraisal. These findings provide support for the idea that greater emotion coherence promotes well-being and also shed light on factors that are associated with the magnitude of coherence. (PsycInfo Database Record (c) 2020 APA, all rights reserved)
Investigator and independent review committee exploratory assessment and verification of tumor response in a non-Hodgkin lymphoma study
Interpretation of endpoints (e.g. overall response rate) in clinical trials depends on the accurate and reliable measurement and identification of tumors. Regulatory agencies recommend blinded reviews of imaging data by independent review committees (IRCs). Differences in response outcomes that arise between IRCs and site investigators raise regulatory/sponsor concerns. Here, we evaluate discrepant tumor response assessments by the IRC and unblinded investigators (complete versus partial response, respectively) occurring in 52 (13% of 393 IRC-assessed responders) of 447 enrolled patients with treatment-naïve non-Hodgkin lymphoma from a randomized study. The IRC and investigators were \u27likely correct\u27 in 73% and 25% of cases, respectively (p \u3c .001). Investigators were more likely to make errors by misinterpreting lymph node data and not utilizing PET results. This post hoc finding suggests a possible role for post-training site evaluation/audit, with retraining as needed, and a specialized consensus committee for concurrent blinded review of site/central data
Poor caregiver mental health predicts mortality of patients with neurodegenerative disease.
Dementia and other neurodegenerative diseases cause profound declines in functioning; thus, many patients require caregivers for assistance with daily living. Patients differ greatly in how long they live after disease onset, with the nature and severity of the disease playing an important role. Caregiving can also be extremely stressful, and many caregivers experience declines in mental health. In this study, we investigated the role that caregiver mental health plays in patient mortality. In 176 patient-caregiver dyads, we found that worse caregiver mental health predicted greater patient mortality even when accounting for key risk factors in patients (i.e., diagnosis, age, sex, dementia severity, and patient mental health). These findings highlight the importance of caring for caregivers as well as patients when attempting to improve patients' lives
Polarized Narrow-Line Emission from the Nucleus of NGC 4258
The detection of polarized continuum and line emission from the nucleus of
NGC 4258 by Wilkes et al. (1995) provides an intriguing application of the
unified model of Seyfert nuclei to a galaxy in which there is known to be an
edge-on, rotating disk of molecular gas surrounding the nucleus. Unlike most
Seyfert nuclei, however, NGC 4258 has strongly polarized narrow emission lines.
To further investigate the origin of the polarized emission, we have obtained
spectropolarimetric observations of the NGC 4258 nucleus at the Keck-II
telescope. The narrow-line polarizations range from 1.0% for [S II] 6716 to
13.9% for the [O II] 7319,7331 blend, and the position angle of polarization is
oriented nearly parallel to the projected plane of the masing disk. A
correlation between critical density and degree of polarization is detected for
the forbidden lines, indicating that the polarized emission arises from
relatively dense (n_e > 10^4 cm^-3) gas. An archival Hubble Space Telescope
narrow-band [O III] image shows that the narrow-line region has a compact,
nearly unresolved core, implying a FWHM size of <2.5 pc. We discuss the
possibility that the polarized emission might arise from the accretion disk
itself and become polarized by scattering within the disk atmosphere. A more
likely scenario is an obscuring torus or strongly warped disk surrounding the
inner portion of a narrow-line region which is strongly stratified in density.
The compact size of the narrow-line region implies that the obscuring structure
must be smaller than ~2.5 pc in diameter.Comment: To appear in the Astronomical Journal. 13 pages, including 1 table
and 4 figures. Uses emulateapj.st
Does backreaction enforce the averaged null energy condition in semiclassical gravity?
The expected stress-energy tensor of quantum fields generically
violates the local positive energy conditions of general relativity. However,
may satisfy some nonlocal conditions such as the averaged null energy
condition (ANEC), which would rule out traversable wormholes. Although ANEC
holds in Minkowski spacetime, it can be violated in curved spacetimes if one is
allowed to choose the spacetime and quantum state arbitrarily, without
imposition of the semiclassical Einstein equation G_{ab} = 8 \pi . In
this paper we investigate whether ANEC holds for solutions to this equation, by
studying a free, massless scalar field with arbitrary curvature coupling in
perturbation theory to second order about the flat spacetime/vacuum solution.
We "reduce the order" of the perturbation equations to eliminate spurious
solutions, and consider the limit in which the lengthscales determined by the
incoming state are much larger than the Planck length. We also need to assume
that incoming classical gravitational radiation does not dominate the first
order metric perturbation. We find that although the ANEC integral can be
negative, if we average the ANEC integral transverse to the geodesic with a
suitable Planck scale smearing function, then a strictly positive result is
obtained in all cases except for the flat spacetime/vacuum solution. This
result suggests --- in agreement with conclusions drawn by Ford and Roman from
entirely independent arguments --- that if traversable wormholes do exist as
solutions to the semiclassical equations, they cannot be macroscopic but must
be ``Planck scale''. A large portion of our paper is devoted to the analysis of
general issues concerning the nature of the semiclassical Einstein equation and
of prescriptions for extracting physically relevant solutions.Comment: 54 pages, 3 figures, uses revtex macros and epsf.tex, to appear in
Phys Rev D. A new appendix has been added showing consistency of our results
with recent results of Visser [gr-qc/9604008]. Some corrections were made to
Appendix A, and several other minor changes to the body of the paper also
were mad
Mechanical thrombectomy in patients with acute ischemic stroke: a cost-effectiveness and value of implementation analysis
Background:
Recent clinical trials have demonstrated the efficacy of mechanical thrombectomy in acute ischemic stroke.
Aims:
To determine the cost-effectiveness, value of future research, and value of implementation of mechanical thrombectomy.
Methods:
Using UK clinical and cost data from the Pragmatic Ischemic Stroke Thrombectomy Evaluation (PISTE) trial, we estimated the cost-effectiveness of mechanical thrombectomy over time horizons of 90-days and lifetime, based on a decision-analytic model, using all existing evidence. We performed a meta-analysis of seven clinical trials to estimate treatment effects. We used sensitivity analysis to address uncertainty. Value of implementation analysis was used to estimate the potential value of additional implementation activities to support routine delivery of mechanical thrombectomy.
Results:
Over the trial period (90 days), compared with best medical care alone, mechanical thrombectomy incurred an incremental cost of £5207 and 0.025 gain in QALY (incremental cost-effectiveness ratio (ICER) £205,279), which would not be considered cost-effective. However, mechanical thrombectomy was shown to be cost-effective over a lifetime horizon, with an ICER of £3466 per QALY gained. The expected value of perfect information per patient eligible for mechanical thrombectomy in the UK is estimated at £3178. The expected value of full implementation of mechanical thrombectomy is estimated at £1.3 billion over five years.
Conclusion:
Mechanical thrombectomy was cost-effective compared with best medical care alone over a patient’s lifetime. On the assumption of 30% implementation being achieved throughout the UK healthcare system, we estimate that the population health benefits obtained from this treatment are greater than the cost of implementation.
Trial registration:
NCT01745692
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