771 research outputs found
The Probability Density of the Higgs Boson Mass
The LEP Collaborations have reported a small excess of events in their
combined Higgs boson analysis at center of mass energies up to about 208 GeV.
In this communication, I present the result of a calculation of the probability
distribution function of the Higgs boson mass which can be rigorously obtained
if the validity of the Standard Model is assumed. It arises from the
combination of the most recent set of precision electroweak data and the
current results of the Higgs searches at LEP 2.Comment: 3 pages, 2 figure
A simple formula for pooling knowledge about a quantum system
When various observers obtain information in an independent fashion about a
classical system, there is a simple rule which allows them to pool their
knowledge, and this requires only the states-of-knowledge of the respective
observers. Here we derive an equivalent quantum formula. While its realm of
applicability is necessarily more limited, it does apply to a large class of
measurements, and we show explicitly for a single qubit that it satisfies the
intuitive notions of what it means to pool knowledge about a quantum system.
This analysis also provides a physical interpretation for the trace of the
product of two density matrices.Comment: 5 pages, Revtex
Women's Perceptions of Contributory Factors for Not Achieving a Vaginal Birth After Cesarean (VBAC)
BACKGROUND: With cesarean rates around the world escalating, concern is growing around why women wanting a vaginal birth after cesarean (VBAC) are not achieving their goal. AIM: To gain an understanding of womenâs perceptions of factors they felt contributed to not achieving a VBAC. SETTING AND PARTICIPANTS: Fifteen women were interviewed following a nonelective repeat cesarean section (NERCS). They had attended a Western Australian midwifery-led service, next birth after cesarean (NBAC), and labored but were not successful in achieving a VBAC because of reasons around delayed progress. Interview transcripts were analyzed using Colaizziâs method of thematic analysis. FINDINGS: Five themes emerged: âTentative commitment with lingering doubts,â âMy body failed me,â âCompromised by a longer than tolerable labor,â âUnable to effectively self-advocate in a climate of power struggling and poor support,â and âThe inflexibility of hospital processes.â The final theme included two subthemes: âRestrictive policiesâ on labor and use of the cardiotocography, âThe CTG.â CONCLUSIONS: When labor did not progress as envisaged and hospital processes adversely affected how women were supported, womenâs doubts around being able to achieve a VBAC were reinforced with a NERCS. Maternity services need to ensure clinical practice reflects best evidence while assuring staff are supportive of womenâs choice
Fitting in a complex chi^2 landscape using an optimized hypersurface sampling
Fitting a data set with a parametrized model can be seen geometrically as
finding the global minimum of the chi^2 hypersurface, depending on a set of
parameters {P_i}. This is usually done using the Levenberg-Marquardt algorithm.
The main drawback of this algorithm is that despite of its fast convergence, it
can get stuck if the parameters are not initialized close to the final
solution. We propose a modification of the Metropolis algorithm introducing a
parameter step tuning that optimizes the sampling of parameter space. The
ability of the parameter tuning algorithm together with simulated annealing to
find the global chi^2 hypersurface minimum, jumping across chi^2{P_i} barriers
when necessary, is demonstrated with synthetic functions and with real data
What is the healthcare utilisation and out-of-pocket expenditure associated with osteoarthritis? A cross-sectional study.
OBJECTIVE: To examine the use and out-of-pocket expenses resulting from consultations, products and practices across conventional, self-care, and complementary medicine (CM) treatments for osteoarthritis (OA) among Australian women. DESIGN, SETTING AND PARTICIPANTS: A cross-sectional survey of 800 women from the 45 and Up Study who had reported a clinical diagnosis of OA. OUTCOME MEASURES: Women's use of conventional, CM and self-prescribed treatments for OA and the associated out-of-pocket cost. RESULTS: Completed questionnaires were returned by 403 women (50.4%). Their average time since the first diagnosis of OA was 15.4 years, and self-rated severity of OA was 5.1 (out of 10) over the past 12 months. During the previous year, 67.0% of the women consulted a doctor, 39.2% consulted an allied health practitioner and 34.7% consulted a CM practitioner for their OA. Some women (19%) consulted with practitioner(s) from all three practitioner groups, 27% consulted with practitioner(s) from two of the three practitioner groups, while 6% consulted with a CM practitioner only. Women with a greater time since diagnosis had more consultations, as did women who rated their OA as more severe. Women's average combined out-of-pocket expenditure for OA-related healthcare consultations, prescription medications, products, and practices was 873 million per annum. CONCLUSIONS: Australian women with OA use a range of conventional and CM consultations, self-care, products and practices to manage their condition, incurring significant out-of-pocket expenses. Given the high individual and societal burden of OA, there is a need for further research into the concurrent use of different healthcare resources with a view to providing safe, cost-effective management of OA across the healthcare system and the wider community
Detection methods for non-Gaussian gravitational wave stochastic backgrounds
We address the issue of finding an optimal detection method for a
discontinuous or intermittent gravitational wave stochastic background. Such a
signal might sound something like popcorn popping. We derive an appropriate
version of the maximum likelihood detection statistic, and compare its
performance to that of the standard cross-correlation statistic both
analytically and with Monte Carlo simulations. The maximum likelihood statistic
performs better than the cross-correlation statistic when the background is
sufficiently non-Gaussian. For both ground and space based detectors, this
results in a gain factor, ranging roughly from 1 to 3, in the minimum
gravitational-wave energy density necessary for detection, depending on the
duty cycle of the background. Our analysis is exploratory, as we assume that
the time structure of the events cannot be resolved, and we assume white,
Gaussian noise in two collocated, aligned detectors. Before this detection
method can be used in practice with real detector data, further work is
required to generalize our analysis to accommodate separated, misaligned
detectors with realistic, colored, non-Gaussian noise.Comment: 25 pages, 12 figures, submitted to physical review D, added revisions
in response to reviewers comment
Bayesian analysis of exoplanet and binary orbits
We introduce BASE (Bayesian astrometric and spectroscopic exoplanet detection
and characterisation tool), a novel program for the combined or separate
Bayesian analysis of astrometric and radial-velocity measurements of potential
exoplanet hosts and binary stars. The capabilities of BASE are demonstrated
using all publicly available data of the binary Mizar A.Comment: Accepted for publication in Astronomy & Astrophysic
T helper cell subsets specific for pseudomonas aeruginosa in healthy individuals and patients with cystic fibrosis
Background: We set out to determine the magnitude of antigen-specific memory T helper cell responses to Pseudomonas aeruginosa in healthy humans and patients with cystic fibrosis.
Methods: Peripheral blood human memory CD4+ T cells were co-cultured with dendritic cells that had been infected with different strains of Pseudomonas aeruginosa. The T helper response was determined by measuring proliferation, immunoassay of cytokine output, and immunostaining of intracellular cytokines.
Results: Healthy individuals and patients with cystic fibrosis had robust antigen-specific memory CD4+ T cell responses to Pseudomonas aeruginosa that not only contained a Th1 and Th17 component but also Th22 cells. In contrast to previous descriptions of human Th22 cells, these Pseudomonal-specific Th22 cells lacked the skin homing markers CCR4 or CCR10, although were CCR6+. Healthy individuals and patients with cystic fibrosis had similar levels of Th22 cells, but the patient group had significantly fewer Th17 cells in peripheral blood.
Conclusions: Th22 cells specific to Pseudomonas aeruginosa are induced in both healthy individuals and patients with cystic fibrosis. Along with Th17 cells, they may play an important role in the pulmonary response to this microbe in patients with cystic fibrosis and other conditions
Differentiating mania/hypomania from happiness using a machine learning analytic approach.
Background: This study aimed to improve the accuracy of bipolar disorder diagnoses by identifying symptoms that help to distinguish mania/hypomania in bipolar disorders from general âhappinessâ in those with unipolar depression. Methods: An international sample of 165 bipolar and 29 unipolar depression patients (as diagnosed by their clinician) were recruited. All participants were required to rate a set of 96 symptoms with regards to whether they typified their experiences of manic/hypomanic states (for bipolar patients) or when they were âhappyâ (unipolar patients). A machine learning paradigm (prediction rule ensembles; PREs) was used to derive rule ensembles that identified which of the 94 non-psychotic symptoms and their combinations best predicted clinically-allocated diagnoses. Results: The PREs were highly accurate at predicting clinician bipolar and unipolar diagnoses (92% and 91% respectively). A total of 20 items were identified from the analyses, which were all highly discriminating across the two conditions. When compared to a classificatory approach insensitive to the weightings of the items, the ensembles were of comparable accuracy in their discriminatory capacity despite the unbalanced sample. This illustrates the potential for PREs to supersede traditional classificatory approaches. Limitations: There were considerably less unipolar than bipolar patients in the sample, which limited the overall accuracy of the PREs. Conclusions: The consideration of symptoms outlined in this study should assist clinicians in distinguishing between bipolar and unipolar disorders. Future research will seek to further refine and validate these symptoms in a larger and more balanced sample
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