704 research outputs found
Severe maternal morbidity following stillbirth in Western Australia 2000â2015: a population-based study
Purpose
There is scant literature about the management of stillbirth and the subsequent risk of severe maternal morbidity (SMM). We aimed to assess the risk of SMM associated with stillbirths compared with live births and whether this differed by the presence of maternal comorbidities.
Methods
In this retrospective cohort study, we used a population-based dataset of all stillbirths and live birthsââ„â20 weeksâ gestation in Western Australia between 2000 and 2015. SMM was identified using a published Australian composite for use with routinely collected hospital morbidity data. Maternal comorbidities were identified in the Hospital Morbidity Data Collection or the Midwives Notification System using a modified Australian chronic disease composite. Multivariable Poisson regression was used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for factors associated with SMM in analyses stratified by the presence of maternal comorbidities. Singleton and multiple pregnancies were examined separately.
Results
This study included 458,639 singleton births (2319 stillbirths and 456,320 live births). The adjusted RRs for SMM among stillbirths were 2.30 (95% CI 1.77, 3.00) for those without comorbidities and 4.80 (95% CI 4.11, 5.59) (Interaction P valueâ<â0.0001) for those with comorbidities compared to live births without and with comorbidities, respectively.
Conclusion
In Western Australia between 2000 and 2015, mothers of stillbirths both with and without any maternal comorbidities had an increased risk of SMM compared with live births. Further investigation into why women who have had a stillbirth without any existing conditions or pregnancy complications develop SMM is warranted
Trends and burden of diabetes in pregnancy among Aboriginal and non-Aboriginal mothers in Western Australia, 1998â2015
Background
Diabetes in pregnancy (DIP), which includes pre-gestational and gestational diabetes, is more prevalent among Aboriginal women. DIP and its adverse neonatal outcomes are associated with diabetes and cardiovascular disease in the offspring. This study investigated the impact of DIP on trends of large for gestational age (LGA) in Aboriginal and non-Aboriginal populations, and added to the limited evidence on temporal trends of DIP burden in these populations.
Methods
We conducted a retrospective cohort study that included all births in Western Australia between 1998 and 2015 using linked population health datasets. Time trends of age-standardised and crude rates of pre-gestational and gestational diabetes were estimated in Aboriginal and non-Aboriginal mothers. Mixed-effects multivariable logistic regression was used to estimate the association between DIP and population LGA trends over time.
Results
Over the study period, there were 526,319 births in Western Australia, of which 6.4% were to Aboriginal mothers. The age-standardised annual rates of pre-gestational diabetes among Aboriginal mothers rose from 4.3% in 1998 to 5.4% in 2015 and remained below 1% in non-Aboriginal women. The comparable rates for gestational diabetes increased from 6.7 to 11.5% over the study period in Aboriginal women, and from 3.5 to 10.2% among non-Aboriginal mothers. LGA rates in Aboriginal babies remained high with inconsistent and no improvement in pregnancies complicated by gestational diabetes and pre-gestational diabetes, respectively. Regression analyses showed that DIP explained a large part of the increasing LGA rates over time in Aboriginal babies.
Conclusions
There has been a substantial increase in the burden of pre-gestational diabetes (Aboriginal women) and gestational diabetes (Aboriginal and non-Aboriginal) in recent decades. DIP appears to substantially contribute to increasing trends in LGA among Aboriginal babies
Particle creation in a Robertson-Walker Universe revisited
We reanalyze the problem of particle creation in a 3+1 spatially closed
Robertson-Walker space-time. We compute the total number of particles produced
by this non-stationary gravitational background as well as the corresponding
total energy and find a slight discrepancy between our results and those
recently obtained in the literatur
An Assessment of the Use of Chimpanzees in Hepatitis C Research Past, Present and Future: 1. Validity of the Chimpanzee Model
The USA is the only significant user of chimpanzees in biomedical research in the world, since many countries have banned or limited the practice due to substantial ethical, economic and scientific concerns. Advocates of chimpanzee use cite hepatitis C research as a major reason for its necessity and continuation, in spite of supporting evidence that is scant and often anecdotal. This paper examines the scientific and ethical issues surrounding chimpanzee hepatitis C research, and concludes that claims of the necessity of chimpanzees in historical and future hepatitis C research are exaggerated and unjustifiable, respectively. The chimpanzee model has several major scientific, ethical, economic and practical caveats. It has made a relatively negligible contribution to knowledge of, and tangible progress against, the hepatitis C virus compared to non-chimpanzee research, and must be considered scientifically redundant, given the array of alternative methods of inquiry now available. The continuation of chimpanzee use in hepatitis C research adversely affects scientific progress, as well as chimpanzees and humans in need of treatment. Unfounded claims of its necessity should not discourage changes in public policy regarding the use of chimpanzees in US laboratories
Visually Impaired OLder people's Exercise programme for falls prevenTion (VIOLET): a feasibility study
This study aims to conduct a mixed methods feasibility study to inform the design and conduct of a future definitive RCT of an adapted exercise programme to prevent falls by reducing fear of falling among older people with visual impairment (OPVI). The research questions are: can an existing exercise programme be adapted for OPVI and successfully delivered in the community; is it feasible to conduct an RCT of this intervention and what are the features of a future definitive trial? We propose to: (i) Adapt an existing exercise programme with the full involvement of OPVI and practitioners; (ii) Run a feasibility study in 2 sites to test our proposed measures, trial processes and recruitment; explore acceptability of the intervention; fidelity of and compliance with the intervention. Two stakeholder panels will be established including OPVI aged 60 and over from Newcastle Society for Blind People (NSBP) and Visibility in Glasgow, practitioners and researchers. They will work together to adapt the FaME programme, which is known to be effective in reducing falls in frequent fallers, so that the methods are acceptable for OPVI, whilst retaining the effective components of the exercise. The panels will meet 4 times to adapt the intervention and contribute to decisions on outcome measures and data collection. During this time we will identify OPVI wishing to act as expert stakeholders in the subsequent WPs. OPVI aged 60+ will be recruited from low vision clinics and voluntary organisations and randomised into the intervention or comparator arm. Those in the comparator arm will receive no intervention, but will be offered it after final data collection. The core components of the adapted exercise programme aim to strengthen leg muscles and retrain balance. However, the detail of the methods and timing will be decided by the stakeholder panel. The programme is likely to run once a week over 12 weeks, with each session lasting up to one hour. The final form of delivery will be one of the outcomes of the PPI work in WP1. Participants will be provided with instructions and equipment to do the exercises at home if they wish. The intervention will be delivered by exercise instructors engaged by Health Works, Newcastle and Visibility, Glasgow, in venues agreed with participants. The final primary outcome of the future RCT will be decided by the responsiveness to change, participant burden and participant feedback from this study. The likely candidate primary outcome is fear of falling (Short FES-I scale). The main secondary outcomes will be: activity avoidance; balance/falls risk; number of falls; quality of life; loneliness; depression; adherence to exercise programme; self-reported home exercising. An estimate of cost effectiveness and cost utility of the intervention will be undertaken. In-depth interviews with a sample of OPVI will be conducted to explore their reasons for taking part/not taking part; factors that facilitate/hinder them from participating in exercise groups; their experiences of the recruitment and randomisation process and views on the outcome measures; their experience of the adapted intervention. The interviews will highlight site specific issues to consider for the definitive RCT. Structured interviews will be undertaken with commissioners and practitioners to explore their perspectives on the application of the intervention
Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing
Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and
four-wave mixing (FWM) experiments were performed simultaneously to study the
initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats
between the A-B excitons were found \textit{only for positive time delay} in
both PP and FWM experiments. The rise time at negative time delay for the
differential reflection spectra was much slower than the FWM signal or PP
differential transmission spectroscopy (DTS) at the exciton resonance. A
numerical solution of a six band semiconductor Bloch equation model including
nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS
results from excitation induced dephasing (EID), that is, the strong density
dependence of the dephasing time which changes with the laser excitation
energy.Comment: 8 figure
Early mortality among Aboriginal and non-Aboriginal women who had a preterm birth in Western Australia: A population-based cohort study
Background: Having a preterm (<37âweeks' gestation) birth may increase a woman's risk of early mortality. Aboriginal and Torres Strait Islander (hereafter Aboriginal) women have higher preterm birth and mortality rates compared with other Australian women. Objectives: We investigated whether a history of having a preterm birth was associated with early mortality in women and whether these associations differed by Aboriginal status. Methods: This retrospective cohort study used population-based perinatal records of women who had a singleton birth between 1980 and 2015 in Western Australia linked to Death Registry data until June 2018. The primary and secondary outcomes were all-cause and cause-specific mortality respectively. After stratification by Aboriginal status, rate differences were calculated, and Cox proportional hazard regression was used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for allcause and cause-specific mortality. Results: There were 20,244 Aboriginal mothers (1349 deaths) and 457,357 nonAboriginal mothers (7646 deaths) with 8.6 million person-years of follow-up. The all-cause mortality rates for Aboriginal mothers who had preterm births and term births were 529.5 and 344.0 (rate difference 185.5, 95% CI 135.5, 238.5) per 100,000 person-years respectively. Among non-Aboriginal mothers, the corresponding figures were 125.5 and 88.6 (rate difference 37.0, 95% CI 29.4, 44.9) per 100,000 personyears. The HR for all-cause mortality for Aboriginal and non-Aboriginal mothers associated with preterm birth were 1.48 (95% CI 1.32, 1.66) and 1.35 (95% CI 1.26, 1.44), respectively, compared with term birth. Compared with mothers who had term births, mothers of preterm births had higher relative risks of mortality from diabetes, cardiovascular, digestive and external causes. Conclusions: Both Aboriginal and non-Aboriginal women who had a preterm birth had a moderately increased risk of mortality up to 38âyears after the birth, reinforcing the importance of primary prevention and ongoing screening.Helen D. Bailey, Caitlin Gray, Akilew A. Adane, Natalie A. Strobel, Scott W. White, Rhonda Marriott, Gizachew A. Tessema, Carrington C. J. Shepherd, Mary Shar
Phonon Pulse Shape Discrimination in SuperCDMS Soudan
SuperCDMS is the next phase of the Cryogenic Dark Matter Search experiment,
which measures both phonon and charge signals generated by particle recoils
within a germanium target mass. Charge signals are employed both in the
definition of a fiducial volume and in the rejection of electron recoil
background events. Alternatively, phonons generated by the charge carriers can
also be used for the same two goals. This paper describes preliminary efforts
to observe and quantify these contributions to the phonon signal and then use
them to reject background events. A simple analysis using only one pulse shape
parameter shows bulk electron recoil vs. bulk nuclear recoil discrimination to
the level of 1:10^3 (limited by the statistics of the data), with little
degradation in discrimination ability down to at least 7 keV recoil energy.
Such phonon-only discrimination can provide a useful cross-check to the
standard discrimination methods, and it also points towards the potential of a
device optimized for a phonon-only measurement.Comment: Low Temperature Detector 14 conference proceedings, to be published
in a special issue of the Journal of Low Temperature Physic
Conformal Invariance, Dark Energy, and CMB Non-Gaussianity
In addition to simple scale invariance, a universe dominated by dark energy
naturally gives rise to correlation functions possessing full conformal
invariance. This is due to the mathematical isomorphism between the conformal
group of certain 3 dimensional slices of de Sitter space and the de Sitter
isometry group SO(4,1). In the standard homogeneous isotropic cosmological
model in which primordial density perturbations are generated during a long
vacuum energy dominated de Sitter phase, the embedding of flat spatial sections
in de Sitter space induces a conformal invariant perturbation spectrum and
definite prediction for the shape of the non-Gaussian CMB bispectrum. In the
case in which the density fluctuations are generated instead on the de Sitter
horizon, conformal invariance of the horizon embedding implies a different but
also quite definite prediction for the angular correlations of CMB
non-Gaussianity on the sky. Each of these forms for the bispectrum is intrinsic
to the symmetries of de Sitter space and in that sense, independent of specific
model assumptions. Each is different from the predictions of single field slow
roll inflation models which rely on the breaking of de Sitter invariance. We
propose a quantum origin for the CMB fluctuations in the scalar gravitational
sector from the conformal anomaly that could give rise to these
non-Gaussianities without a slow roll inflaton field, and argue that conformal
invariance also leads to the expectation for the relation n_S-1=n_T between the
spectral indices of the scalar and tensor power spectrum. Confirmation of this
prediction or detection of non-Gaussian correlations in the CMB of one of the
bispectral shape functions predicted by conformal invariance can be used both
to establish the physical origins of primordial density fluctuations and
distinguish between different dynamical models of cosmological vacuum dark
energy.Comment: 73 pages, 9 figures. Final Version published in JCAP. New Section 4
added on linearized scalar gravitational potentials; New Section 8 added on
gravitational wave tensor perturbations and relation of spectral indices n_T
= n_S -1; Table of Contents added; Eqs. (3.14) and (3.15) added to clarify
relationship of bispectrum plotted to CMB measurements; Some other minor
modification
Mindfulness meditators show altered distributions of early and late neural activity markers of attention in a response inhibition task
Attention is vital for optimal behavioural performance in every-day life. Mindfulness meditation has been shown to enhance attention. However, the components of attention altered by meditation and the related neural activities are underexplored. In particular, the contributions of inhibitory processes and sustained attention are not well understood. To address these points, 34 meditators were compared to 28 age and gender matched controls during electroencephalography (EEG) recordings of neural activity during a Go/Nogo response inhibition task. This task generates a P3 event related potential, which is related to response inhibition processes in Nogo trials, and attention processes across both trial types. Compared with controls, meditators were more accurate at responding to Go and Nogo trials. Meditators showed a more frontally distributed P3 to both Go and Nogo trials, suggesting more frontal involvement in sustained attention rather than activity specific to response inhibition. Unexpectedly, meditators also showed increased positivity over the right parietal cortex prior to visual information reaching the occipital cortex (during the pre-C1 window). Both results were positively related to increased accuracy across both groups. The results suggest that meditators show altered engagement of neural regions related to attention, including both higher order processes generated by frontal regions, and sensory anticipation processes generated by poster regions. This activity may reflect an increased capacity to modulate a range of neural processes in order to meet task requirements. This increased capacity may underlie the improved attentional function observed in mindfulness meditators.Neil W. Bailey, Gabrielle Freedman, Kavya Raj, Caley M. Sullivan, Nigel C. Rogasch, Sung W. Chung, Kate E. Hoy, Richard Chambers, Craig Hassed, Nicholas T. Van Dam, Thomas Koenig, Paul B. Fitzgeral
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