1,008 research outputs found
Network Structures and the Properties of Na-Ca-Sr-Borophosphate Glasses
Borophosphate glasses were prepared with the nominal molar compositions 16Na2O-(24-y)CaO-ySrO-xB2O3-(60-x)P2O5 (mol%), where 0â€xâ€60 and y=0, 12, and 24. Information about the compositional dependence of borate and phosphate site speciation and next nearest neighbor linkages was obtained by 11B and 31P MAS NMR and Raman spectroscopies, and by high pressure liquid chromatography (HPLC). With the initial replacement of P2O5 by B2O3, tetrahedral borate sites linked to four phosphate anions, B(ĂP)4, are created in the glass structure, and the average phosphate anion becomes smaller as bridging PĂP bonds are replaced by bridging PĂB bonds. With further increases in the B2O3 content, borate units, including B-triangles, replace phosphate units linked to the B-tetrahedra. Compositional trends for the glass transition temperature (Tg) and molar volume are explained by considering the number and types of bridging oxygens per glass former, consistent with topological models reported elsewhere
Data fusion with Gaussian processes for estimation of environmental hazard events
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordThe data that support the findings of this study are openly available at https://wisc.climate.copernicus.eu/wisc/#/
help/products#stormtrack_download, WISC (2019).Environmental hazard events such as extra-tropical cyclones or windstorms that
develop in the North Atlantic can cause severe societal damage. Environmental hazard is quantified by the hazard footprint, a spatial area describing potential damage.
However, environmental hazards are never directly observed, so estimation of the
footprint for any given event is primarily reliant on station observations (e.g., wind
speed in the case of a windstorm event) and physical model hindcasts. Both data
sources are indirect measurements of the true footprint, and here we present a general
statistical framework to combine the two data sources for estimating the underlying
footprint. The proposed framework extends current data fusion approaches by allowing structured Gaussian process discrepancy between physical model and the true
footprint, while retaining the elegance of how the "change of support" problem is
dealt with. Simulation is used to assess the practical feasibility and efficacy of the
framework, which is then illustrated using data on windstorm ImogenNatural Environment Research Council (NERC
Diagnostic accuracy of single baseline measurement of Elecsys Troponin T high-sensitive assay for diagnosis of acute myocardial infarction in emergency department: systematic review and meta-analysis
Published onlineJournal ArticleMeta-AnalysisResearch Support, Non-U.S. Gov'tReviewOBJECTIVE: To obtain summary estimates of the accuracy of a single baseline measurement of the Elecsys Troponin T high-sensitive assay (Roche Diagnostics) for the diagnosis of acute myocardial infarction in patients presenting to the emergency department. DESIGN: Systematic review and meta-analysis of diagnostic test accuracy studies. DATA SOURCES: Medline, Embase, and other relevant electronic databases were searched for papers published between January 2006 and December 2013. STUDY SELECTION: Studies were included if they evaluated the diagnostic accuracy of a single baseline measurement of Elecsys Troponin T high-sensitive assay for the diagnosis of acute myocardial infarction in patients presenting to the emergency department with suspected acute coronary syndrome. STUDY APPRAISAL AND DATA SYNTHESIS: The first author screened all titles and abstracts identified through the searches and selected all potentially relevant papers. The screening of the full texts, the data extraction, and the methodological quality assessment, using the adapted QUADAS-2 tool, were conducted independently by two reviewers with disagreements being resolved through discussion or arbitration. If appropriate, meta-analysis was conducted using the hierarchical bivariate model. RESULTS: Twenty three studies reported the performance of the evaluated assay at presentation. The results for 14 ng/L and 3-5 ng/L cut-off values were pooled separately. At 14 ng/L (20 papers), the summary sensitivity was 89.5% (95% confidence interval 86.3% to 92.1%) and the summary specificity was 77.1% (68.7% to 83.7%). At 3-5 ng/L (six papers), the summary sensitivity was 97.4% (94.9% to 98.7%) and the summary specificity was 42.4% (31.2% to 54.5%). This means that if 21 of 100 consecutive patients have the target condition (21%, the median prevalence across the studies), 2 (95% confidence interval 2 to 3) of 21 patients with acute myocardial infarction will be missed (false negatives) if 14 ng/L is used as a cut-off value and 18 (13 to 25) of 79 patients without acute myocardial infarction will test positive (false positives). If the 3-5 ng/L cut-off value is used, <1 (0 to 1) patient with acute myocardial infarction will be missed and 46 (36 to 54) patients without acute myocardial infarction will test positive. CONCLUSIONS: The results indicate that a single baseline measurement of the Elecsys Troponin T high-sensitive assay could be used to rule out acute myocardial infarction if lower cut-off values such as 3 ng/L or 5 ng/L are used. However, this method should be part of a comprehensive triage strategy and may not be appropriate for patients who present less than three hours after symptom onset. Care must also be exercised because of the higher imprecision of the evaluated assay and the greater effect of lot-to-lot reagent variation at low troponin concentrations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42013003926.This research was funded by the South West Academic Health Science Network (AHSN) and the National Institute for Health Research (NIHR) Collaboration for Leadership for Applied Health Research and Care for the South West Peninsula
Four-nucleon contact interactions from holographic QCD
We calculate the low energy constants of four-nucleon interactions in an
effective chiral Lagrangian in holographic QCD. We start with a D4-D8 model to
obtain meson-nucleon interactions and then integrate out massive mesons to
obtain the four-nucleon interactions in 4D. We end up with two low energy
constants at the leading order and seven of them at the next leading order,
which is consistent with the effective chiral Lagrangian. The values of the low
energy constants are evaluated with the first five Kaluza-Klein resonances.Comment: 28 page
Meson Exchange Effect on Color Superconductivity
We investigate the effects of pion and gluon exchanges on the formation of
two-flavor color superconductivity at moderate density, . The
chiral quark model proposed by Manohar and Georgi containing pions as well as
gluons is employed to show that the pion exchange reduces substantially the
value of the superconducting gap gotten with the gluon exchange only. It turns
out that the pion exchanges produce a repulsion between quark-quark pair in a
spin and isospin singlet state.
We suggest that the phase consisiting of pions, gluons and quarks is one of
the candidates of in-medium QCD phase at moderate density.Comment: 8 pages, 1 figure, minor correction
Finite-Temperature Corrections in the Dilated Chiral Quark Model
We calculate the finite-temperature corrections in the dilated chiral quark
model using the effective potential formalism. Assuming that the dilaton limit
is applicable at some short length scale, we interpret the results to represent
the behavior of hadrons in dense {\it and} hot matter. We obtain the scaling
law, while we argue, using PCAC, that
pion mass does not scale within the temperature range involved in our
Lagrangian. It is found that the hadron masses and the pion decay constant drop
faster with temperature in the dilated chiral quark model than in the
conventional linear sigma model that does not take into account the QCD scale
anomaly. We attribute the difference in scaling in heat bath to the effect of
baryonic medium on thermal properties of the hadrons. Our finding would imply
that the AGS experiments (dense {\it and} hot matter) and the RHIC experiments
(hot and dilute matter) will ``see" different hadron properties in the
hadronization phase.Comment: 13 pages , LaTe
Can majority support save an endangered language? A case study of language attitudes in Guernsey
Many studies of minority language revitalisation focus on the attitudes and perceptions of minorities, but not on those of majority group members. This paper discusses the implications of these issues, and presents research into majority andf minority attitudes towards the endangered indigenous vernacular of Guernsey, Channel Islands. The research used a multi-method approach (questionnaire and interview) to obtain attitudinal data from a representative sample of the population that included politicians and civil servants (209 participants). The findings suggested a shift in language ideology away from the post-second world war âculture of modernisationâ and monolingual ideal, towards recognition of the value of a bi/trilingual linguistic heritage. Public opinion in Guernsey now seems to support the maintenance of the indigenous language variety, which has led to a degree of official support. The paper then discusses to what extent this âattitude shiftâ is reflected in linguistic behaviour and in concrete language planning measures
Vector Manifestation and Fate of Vector Mesons in Dense Matter
We describe in-medium properties of hadrons in dense matter near chiral
restoration using a Wilsonian matching to QCD of an effective field theory with
hidden local symmetry at the chiral cutoff . We find that chiral
symmetry is restored in vector manifestation \`a la Harada and Yamawaki at a
critical matter density . We express the critical density in terms of QCD
correlators in dense matter at the matching scale. In a manner completely
analogous to what happens at the critical and at the critical
temperature , the vector meson mass is found to vanish (in the chiral
limit) at chiral restoration. This result provides a support for Brown-Rho
scaling predicted a decade ago.Comment: 14 pages, 2 figure
Symmetry energy of dense matter in holographic QCD
We study the nuclear symmetry energy of dense matter using holographic QCD.
To this end, we consider two flavor branes with equal quark masses in a
D4/D6/D6 model. We find that at all densities the symmetry energy monotonically
increases. At small densities, it exhibits a power law behavior with the
density, .Comment: 9 pages, 3 figure
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