313 research outputs found
Updated stellar yields from Asymptotic Giant Branch models
An updated grid of stellar yields for low to intermediate-mass
thermally-pulsing Asymptotic Giant Branch (AGB) stars are presented. The models
cover a range in metallicity Z = 0.02, 0.008, 0.004, and 0.0001, and masses
between 1Msun to 6Msun. New intermediate-mass Z = 0.0001 AGB models are also
presented, along with a finer mass grid than used in previous studies. The
yields are computed using an updated reaction rate network that includes the
latest NeNa and MgAl proton capture rates, with the main result that between ~6
to 30 times less Na is produced by intermediate-mass models with hot bottom
burning. In low-mass AGB models we investigate the effect on the production of
light elements of including some partial mixing of protons into the intershell
region during the deepest extent of each third dredge-up episode. The protons
are captured by the abundant 12C to form a 13C pocket. The 13C pocket increases
the yields of 19F, 23Na, the neutron-rich Mg and Si isotopes, 60Fe, and 31P.
The increase in 31P is by factors of ~4 to 20, depending on the metallicity.
Any structural changes caused by the addition of the 13C pocket into the
He-intershell are ignored. However, the models considered are of low mass and
any such feedback is likely to be small. Further study is required to test the
accuracy of the yields from the partial-mixing models. For each mass and
metallicity, the yields are presented in a tabular form suitable for use in
galactic chemical evolution studies or for comparison to the composition of
planetary nebulae.Comment: Accepted for publication in MNRAS; 15 page
SuperWASP Observations of the 2007 Outburst of Comet 17P/Holmes
We present wide-field imaging of the 2007 outburst of Comet 17P/Holmes
obtained serendipitously by SuperWASP-North on 17 nights over a 42-night period
beginning on the night (2007 October 22-23) immediately prior to the outburst.
Photometry of 17P's unresolved coma in SuperWASP data taken on the first night
of the outburst is consistent with exponential brightening, suggesting that the
rapid increase in the scattering cross-section of the coma could be largely due
to the progressive fragmentation of ejected material produced on a very short
timescale at the time of the initial outburst, with fragmentation timescales
decreasing from t(frag)~2x10^3 s to t(frag)~1x10^3 s over our observing period.
Analysis of the expansion of 17P's coma reveals a velocity gradient suggesting
that the outer coma was dominated by material ejected in an instantaneous,
explosive manner. We find an expansion velocity at the edge of the dust coma of
v(exp) = 0.55+/-0.02 km/s and a likely outburst date of t_0=2007 October
23.3+/-0.3, consistent with our finding that the comet remained below
SuperWASP's detection limit of m(V)~15 mag until at least 2007 October 23.3.
Modelling of 17P's gas coma indicates that its outer edge, which was observed
to extend past the outer dust coma, is best explained with a single pulse of
gas production, consistent with our conclusions concerning the production of
the outer dust coma.Comment: 36 pages, 8 figures, accepted for publication in MNRA
Core components for effective infection prevention and control programmes: new WHO evidence-based recommendations
Abstract
Health care-associated infections (HAI) are a major public health problem with a significant impact on morbidity, mortality and quality of life. They represent also an important economic burden to health systems worldwide. However, a large proportion of HAI are preventable through effective infection prevention and control (IPC) measures. Improvements in IPC at the national and facility level are critical for the successful containment of antimicrobial resistance and the prevention of HAI, including outbreaks of highly transmissible diseases through high quality care within the context of universal health coverage. Given the limited availability of IPC evidence-based guidance and standards, the World Health Organization (WHO) decided to prioritize the development of global recommendations on the core components of effective IPC programmes both at the national and acute health care facility level, based on systematic literature reviews and expert consensus. The aim of the guideline development process was to identify the evidence and evaluate its quality, consider patient values and preferences, resource implications, and the feasibility and acceptability of the recommendations. As a result, 11 recommendations and three good practice statements are presented here, including a summary of the supporting evidence, and form the substance of a new WHO IPC guideline
New product development resource forecasting
Forecasting resource requirements for new product development (NPD) projects is essential for both strategic and tactical planning. Sophisticated, elegant planning tools to present data and inform decision-making do exist. However, in NPD, such tools run on unreliable, estimation-based resource information derived through undefined processes. This paper establishes that existing methods do not provide transparent, consistent, timely or accurate resource planning information, highlighting the need for a new approach to resource forecasting, specifically in the field of NPD. The gap between the practical issues and available methods highlights the possibility of developing a novel design of experiments approach to create resource forecasting models
A systematic review, evidence synthesis and meta-analysis of quantitative and qualitative studies evaluating the clinical effectiveness, the cost-effectiveness, safety and acceptability of interventions to prevent postnatal depression
Background: Postnatal depression (PND) is a major depressive disorder in the year following childbirth, which impacts on women, their infants and their families. A range of interventions has been developed to prevent PND.
Objectives: To (1) evaluate the clinical effectiveness, cost-effectiveness, acceptability and safety of antenatal and postnatal interventions for pregnant and postnatal women to prevent PND; (2) apply rigorous methods of systematic reviewing of quantitative and qualitative studies, evidence synthesis and decision-analytic modelling to evaluate the preventive impact on women, their infants and their families; and (3) estimate cost-effectiveness.
Data sources: We searched MEDLINE, EMBASE, Science Citation Index and other databases (from inception to July 2013) in December 2012, and we were updated by electronic alerts until July 2013.
Review methods: Two reviewers independently screened titles and abstracts with consensus agreement. We undertook quality assessment. All universal, selective and indicated preventive interventions for pregnant women and women in the first 6 postnatal weeks were included. All outcomes were included, focusing on the Edinburgh Postnatal Depression Scale (EPDS), diagnostic instruments and infant outcomes. The quantitative evidence was synthesised using network meta-analyses (NMAs). A mathematical model was constructed to explore the cost-effectiveness of interventions contained within the NMA for EPDS values.
Results: From 3072 records identified, 122 papers (86 trials) were included in the quantitative review. From 2152 records, 56 papers (44 studies) were included in the qualitative review. The results were inconclusive. The most beneficial interventions appeared to be midwifery redesigned postnatal care [as shown by the mean 12-month EPDS score difference of –1.43 (95% credible interval –4.00 to 1.36)], person-centred approach (PCA)-based and cognitive–behavioural therapy (CBT)-based intervention (universal), interpersonal psychotherapy (IPT)-based intervention and education on preparing for parenting (selective), promoting parent–infant interaction, peer support, IPT-based intervention and PCA-based and CBT-based intervention (indicated). Women valued seeing the same health worker, the involvement of partners and access to several visits from a midwife or health visitor trained in person-centred or cognitive–behavioural approaches. The most cost-effective interventions were estimated to be midwifery redesigned postnatal care (universal), PCA-based intervention (indicated) and IPT-based intervention in the sensitivity analysis (indicated), although there was considerable uncertainty. Expected value of partial perfect information (EVPPI) for efficacy data was in excess of £150M for each population. Given the EVPPI values, future trials assessing the relative efficacies of promising interventions appears to represent value for money.
Limitations: In the NMAs, some trials were omitted because they could not be connected to the main network of evidence or did not provide EPDS scores. This may have introduced reporting or selection bias. No adjustment was made for the lack of quality of some trials. Although we appraised a very large number of studies, much of the evidence was inconclusive.
Conclusions: Interventions warrant replication within randomised controlled trials (RCTs). Several interventions appear to be cost-effective relative to usual care, but this is subject to considerable uncertainty.
Future work recommendations: Several interventions appear to be cost-effective relative to usual care, but this is subject to considerable uncertainty. Future research conducting RCTs to establish which interventions are most clinically effective and cost-effective should be considered
Global Globin Network and adopting genomic variant database requirements for thalassemia
\ua9 The Author(s) 2024. Published by Oxford University Press.Thalassemia is one of the most prevalent monogenic disorders in low- and middle-income countries (LMICs). There are an estimated 270 million carriers of hemoglobinopathies (abnormal hemoglobins and/or thalassemia) worldwide, necessitating global methods and solutions for effective and optimal therapy. LMICs are disproportionately impacted by thalassemia, and due to disparities in genomics awareness and diagnostic resources, certain LMICs lag behind high-income countries (HICs). This spurred the establishment of the Global Globin Network (GGN) in 2015 at UNESCO, Paris, as a project-wide endeavor within the Human Variome Project (HVP). Primarily aimed at enhancing thalassemia clinical services, research, and genomic diagnostic capabilities with a focus on LMIC needs, GGN aims to foster data collection in a shared database by all affected nations, thus improving data sharing and thalassemia management. In this paper, we propose a minimum requirement for establishing a genomic database in thalassemia based on the HVP database guidelines. We suggest using an existing platform recommended by HVP, the Leiden Open Variation Database (LOVD) (https://www.lovd.nl/). Adoption of our proposed criteria will assist in improving or supplementing the existing databases, allowing for better-quality services for individuals with thalassemia. Database URL: https://www.lovd.nl/
Functional and clinical studies reveal pathophysiological complexity of CLCN4-related neurodevelopmental condition
Missense and truncating variants in the X-chromosome-linked CLCN4 gene, resulting in reduced or complete loss-of-function (LOF) of the encoded chloride/proton exchanger ClC-4, were recently demonstrated to cause a neurocognitive phenotype in both males and females. Through international clinical matchmaking and interrogation of public variant databases we assembled a database of 90 rare CLCN4 missense variants in 90 families: 41 unique and 18 recurrent variants in 49 families. For 43 families, including 22 males and 33 females, we collated detailed clinical and segregation data. To confirm causality of variants and to obtain insight into disease mechanisms, we investigated the effect on electrophysiological properties of 59 of the variants in Xenopus oocytes using extended voltage and pH ranges. Detailed analyses revealed new pathophysiological mechanisms: 25% (15/59) of variants demonstrated LOF, characterized by a “shift” of the voltage-dependent activation to more positive voltages, and nine variants resulted in a toxic gain-of-function, associated with a disrupted gate allowing inward transport at negative voltages. Functional results were not always in line with in silico pathogenicity scores, highlighting the complexity of pathogenicity assessment for accurate genetic counselling. The complex neurocognitive and psychiatric manifestations of this condition, and hitherto under-recognized impacts on growth, gastrointestinal function, and motor control are discussed. Including published cases, we summarize features in 122 individuals from 67 families with CLCN4-related neurodevelopmental condition and suggest future research directions with the aim of improving the integrated care for individuals with this diagnosis
Synthesis of thermal insulator using chicken feather fibre in starch-clay nanocomposites
Incorporating chicken feather fibre (CFF) into natural based-nanocomposite comprising of glycerine plasticizedcassava
starch binder with bentonite (BNT) as nanofiller, a thermal insulator (TIN) was synthesized. Central
Composite Design (CCD) Response Surface Methodology was employed to carry out the experimental design using
two factors (CFF and BNT) along with one response (thermal conductivity) to produce nine materials as insulators,
comprising of 0%, 5%, and 10% BNT based on 8 g initial weight of CFF. A sample without CFF was used
as the control. Developed thermal insulators were subjected to thermal conductivity tests using Lee's disc method
at a steady state. The best insulator is TIN-4 with the lowest thermal conductivity of 0.0313 W/(mK) and the
highest insulation property of 114.63 m2k/W, while TIN-10 with no CFF has the highest thermal conductivity of
0.0549 W/(mk) and lowest insulation property of 48.1603 m2k/W. Proportionate use of chicken feather fibre in
starch-clay nanocomposite will help synthesize an effective thermal insulator with minimum cost
Classical Simulation of Relativistic Quantum Mechanics in Periodic Optical Structures
Spatial and/or temporal propagation of light waves in periodic optical
structures offers a rather unique possibility to realize in a purely classical
setting the optical analogues of a wide variety of quantum phenomena rooted in
relativistic wave equations. In this work a brief overview of a few optical
analogues of relativistic quantum phenomena, based on either spatial light
transport in engineered photonic lattices or on temporal pulse propagation in
Bragg grating structures, is presented. Examples include spatial and temporal
photonic analogues of the Zitterbewegung of a relativistic electron, Klein
tunneling, vacuum decay and pair-production, the Dirac oscillator, the
relativistic Kronig-Penney model, and optical realizations of non-Hermitian
extensions of relativistic wave equations.Comment: review article (invited), 14 pages, 7 figures, 105 reference
Diagnostic accuracy of a clinical diagnosis of idiopathic pulmonary fibrosis: An international case-cohort study
We conducted an international study of idiopathic pulmonary fibrosis (IPF) diagnosis among a large group of physicians and compared their diagnostic performance to a panel of IPF experts. A total of 1141 respiratory physicians and 34 IPF experts participated. Participants evaluated 60 cases of interstitial lung disease (ILD) without interdisciplinary consultation. Diagnostic agreement was measured using the weighted kappa coefficient (\u3baw). Prognostic discrimination between IPF and other ILDs was used to validate diagnostic accuracy for first-choice diagnoses of IPF and were compared using the Cindex. A total of 404 physicians completed the study. Agreement for IPF diagnosis was higher among expert physicians (\u3baw=0.65, IQR 0.53-0.72, p20 years of experience (C-index=0.72, IQR 0.0-0.73, p=0.229) and non-university hospital physicians with more than 20 years of experience, attending weekly MDT meetings (C-index=0.72, IQR 0.70-0.72, p=0.052), did not differ significantly (p=0.229 and p=0.052 respectively) from the expert panel (C-index=0.74 IQR 0.72-0.75). Experienced respiratory physicians at university-based institutions diagnose IPF with similar prognostic accuracy to IPF experts. Regular MDT meeting attendance improves the prognostic accuracy of experienced non-university practitioners to levels achieved by IPF experts
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