2,439 research outputs found
Antidepressant use in late gestation and risk of postpartum haemorrhage: a retrospective cohort study
Objective: To investigate the association between antidepressant use in late gestation and postpartum haemorrhage (PPH). Design: Retrospective cohort study. Tertiary teaching hospital in Adelaide, Australia. Population: A total of 30 198 women delivering between 2002 and 2008. Methods: Relative risks adjusted for maternal sociodemographics and comorbidities (aRRs) were calculated for PPH, comparing women with late-gestation exposure to antidepressants (n = 558), women with a psychiatric illness but no antidepressant use (n = 1292), and women with neither antenatal exposures (n = 28 348). Additional sensitivity analyses were undertaken, examining associations with severe PPH and postpartum anaemia. Main Outcome Measures: The primary outcome was PPH, defined as a recorded blood loss of ≥500 mL for vaginal deliveries and ≥1000 mL for caesarean sections. Secondary outcomes included severe PPH (≥1000 mL blood loss, irrespective of method of delivery), and the presence of postpartum anaemia (identified from hospital medical records). Results: Compared with unexposed controls, women exposed to antidepressants had an increased risk of PPH (aRR 1.53; 95% confidence interval, 95% CI 1.25-1.86), whereas no increased risk was observed for women with a psychiatric illness but no antidepressant use (aRR 1.04; 95% CI 0.89-1.23). In sensitivity analyses, late gestation antidepressant exposure was associated with an increased risk of severe PPH (aRR 1.84; 95% CI 1.39-2.44), as well as postpartum anaemia (aRR 1.80; 95% CI 1.46-2.22). Conclusions: Exposure to antidepressants in late gestation was associated with a significantly increased risk of PPH. Although potential confounding by unmeasured factors cannot be ruled out, these findings suggest a direct effect of antidepressant exposure on PPH.LE Grzeskowiak, R McBain, GA Dekker, VL Clifto
Generic Bell correlation between arbitrary local algebras in quantum field theory
We prove that for any two commuting von Neumann algebras of infinite type,
the open set of Bell correlated states for the two algebras is norm dense. We
then apply this result to algebraic quantum field theory -- where all local
algebras are of infinite type -- in order to show that for any two spacelike
separated regions, there is an open dense set of field states that dictate Bell
correlations between the regions. We also show that any vector state cyclic for
one of a pair of commuting nonabelian von Neumann algebras is entangled (i.e.,
nonseparable) across the algebras -- from which it follows that every field
state with bounded energy is entangled across any two spacelike separated
regions.Comment: Third version; correction in the proof of Proposition
Patterns, predictors and outcomes of asthma control and exacerbations during pregnancy: a prospective cohort study
There exists a paucity of data for socially disadvantaged populations describing patterns and predictors of asthma control status and exacerbations during pregnancy, and their relationship to adverse perinatal outcomes. Asthmatic women (n=189) were followed prospectively during pregnancy, with visits at 12, 20, 28 and 36 weeks gestation. Data on loss of control, recurrent uncontrolled asthma and moderate/severe exacerbations were collected at each visit and their relationship to perinatal outcomes examined following stratification for fetal sex. 50% of asthmatic women experienced a loss of control or moderate/severe exacerbation during pregnancy, with 22% of women experiencing a moderate/severe exacerbation. Factors associated with an increased risk of women experiencing recurrent uncontrolled asthma during pregnancy included smoking (relative risk 2.92, 95% CI 1.53-5.58), inhaled corticosteroid use at the beginning of pregnancy (relative risk 2.40, 95% CI 1.25-4.60) and increasing maternal age (relative risk 1.06, 95% CI 1.01-1.11). No factors were associated with moderate/severe exacerbations. Asthma control rather than exacerbations during pregnancy appeared to be most strongly correlated with perinatal outcomes. Following stratification by fetal sex, the presence of recurrent uncontrolled asthma was associated with an increased risk of being small for gestational age in women pregnant with females (33.3% versus 9.5%; p=0.018). In contrast, there was a nonsignificant increased risk of preterm birth in women with recurrent uncontrolled asthma that were pregnant with males (25.0% versus 11.8%; p=0.201) These results suggest that the key to improving perinatal outcomes lies in improving asthma control as early as possible in pregnancy and monitoring throughout pregnancy, rather than focusing on preventing exacerbations alone.Luke E. Grzeskowiak, Brian Smith, Anil Roy, Gustaaf A. Dekker and Vicki L. Clifto
Evolution of a periodic eight-black-hole lattice in numerical relativity
The idea of black-hole lattices as models for the large-scale structure of
the universe has been under scrutiny for several decades, and some of the
properties of these systems have been elucidated recently in the context of the
problem of cosmological backreaction. The complete, three-dimensional and fully
relativistic evolution of these system has, however, never been tackled. We
explicitly construct the first of these solutions by numerically integrating
Einstein's equation in the case of an eight-black-hole lattice with the
topology of S3.Comment: 21 pages, 13 figures. Corrected and clarified discussio
Testing axioms for Quantum Mechanics on Probabilistic toy-theories
In Ref. [1] one of the authors proposed postulates for axiomatizing Quantum
Mechanics as a "fair operational framework", namely regarding the theory as a
set of rules that allow the experimenter to predict future events on the basis
of suitable tests, having local control and low experimental complexity. In
addition to causality, the following postulates have been considered: PFAITH
(existence of a pure preparationally faithful state), and FAITHE (existence of
a faithful effect). These postulates have exhibited an unexpected theoretical
power, excluding all known nonquantum probabilistic theories. Later in Ref. [2]
in addition to causality and PFAITH, postulate LDISCR (local discriminability)
and PURIFY (purifiability of all states) have been considered, narrowing the
probabilistic theory to something very close to Quantum Mechanics. In the
present paper we test the above postulates on some nonquantum probabilistic
models. The first model, "the two-box world" is an extension of the
Popescu-Rohrlich model, which achieves the greatest violation of the CHSH
inequality compatible with the no-signaling principle. The second model "the
two-clock world" is actually a full class of models, all having a disk as
convex set of states for the local system. One of them corresponds to the "the
two-rebit world", namely qubits with real Hilbert space. The third model--"the
spin-factor"--is a sort of n-dimensional generalization of the clock. Finally
the last model is "the classical probabilistic theory". We see how each model
violates some of the proposed postulates, when and how teleportation can be
achieved, and we analyze other interesting connections between these postulate
violations, along with deep relations between the local and the non-local
structures of the probabilistic theory.Comment: Submitted to QIP Special Issue on Foundations of Quantum Informatio
Spherically symmetric solutions in f(R)-gravity via Noether Symmetry Approach
We search for spherically symmetric solutions of f(R) theories of gravity via
the Noether Symmetry Approach. A general formalism in the metric framework is
developed considering a point-like f(R)-Lagrangian where spherical symmetry is
required. Examples of exact solutions are given.Comment: 17 pages, to appear in Class. Quant. Gra
Dynamics of a lattice Universe
We find a solution to Einstein field equations for a regular toroidal lattice
of size L with equal masses M at the centre of each cell; this solution is
exact at order M/L. Such a solution is convenient to study the dynamics of an
assembly of galaxy-like objects. We find that the solution is expanding (or
contracting) in exactly the same way as the solution of a
Friedman-Lema\^itre-Robertson-Walker Universe with dust having the same average
density as our model. This points towards the absence of backreaction in a
Universe filled with an infinite number of objects, and this validates the
fluid approximation, as far as dynamics is concerned, and at the level of
approximation considered in this work.Comment: 14 pages. No figure. Accepted version for Classical and Quantum
Gravit
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LENS Deposition of Complex Geometries
The Laser Engineered Net Shaping (LENS®) system at Sandia National Laboratories, a
laser-based direct metal deposition process, was recently used for the fabrication of a complex
prototype. The LENS process involved the challenges of adjacent areas of thick and thin cross
section, overhanging unsupported features, high aspect ratios, and a hemispherical substrate.
These challenges were overcome through the use of closed-loop weld pool control, height
monitoring, a strong understanding of build parameters, and unique process planning strategies.
The near-net shape LENS part was completed with annealing and conventional machining to
produce the complex components in a reduced timeframe.Mechanical Engineerin
Energy-Conserving Lattice Boltzmann Thermal Model in Two Dimensions
A discrete velocity model is presented for lattice Boltzmann thermal fluid dynamics.
This model is implemented and tested in two dimensions with a finite difference scheme. Comparison with analytical solutions shows an excellent agreement even for wide temperature differences. An alternative approximate approach is then presented for traditional lattice transport schemes
Regulating and Deregulating the Public Utilities 1830-2010
History can provide invaluable insights into important issues of the economic and social regulation of utilities, and offer lessons towards future debates. But the history of utility regulation – which speaks of changing, diverse and complex experiences around the world – was, unfortunately, sidelined or marginalised when economists and policymakers enthusiastically embraced the question of how to reform the utilities from the 1970s. This paper provides an overview of the three, overarching, `waves' of utility regulation from the nineteenth century to the present, documenting how, when and why the ways in which the roles of the state, the market and firms altered over time. It then contextualises and explains the main contributions of each of the papers included in this special issue of Business History, which cover energy, communications, water, transportation and other urban infrastructure regulation, across Western Europe, the United States and Australia
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