277 research outputs found
Chemical Instability of the Cobalt Oxyhydrate Superconductor under Ambient Conditions
The layered sodium cobalt oxyhydrate superconductor Na0.3CoO2*1.4H2O is shown
through X-ray diffraction and thermogravimetric studies to be one of a series
of hydrated phases of Na0.3CoO2. Further, it is shown that the material is
exceptionally sensitive to both temperature and humidity near ambient
conditions, easily dehydrating to a non-superconducting lower hydrate. The
observation of this stable lower hydrate with c=13.8 angstroms implies that the
superconductivity turns on in this system between CoO2 layer spacings of 6.9
and 9.9 angstroms at nominally constant chemical doping.Comment: 10 pages and 4 figure
Scaffolding School Pupils’ Scientific Argumentation with Evidence-Based Dialogue Maps
This chapter reports pilot work investigating the potential of Evidence-based Dialogue Mapping to scaffold young teenagers’ scientific argumentation. Our research objective is to better understand pupils’ usage of dialogue maps created in Compendium to write scientific ex-planations. The participants were 20 pupils, 12-13 years old, in a summer science course for “gifted and talented” children in the UK. Through qualitative analysis of three case studies, we investigate the value of dialogue mapping as a mediating tool in the scientific reasoning process during a set of learning activities. These activities were published in an online learning envi-ronment to foster collaborative learning. Pupils mapped their discussions in pairs, shared maps via the online forum and in plenary discussions, and wrote essays based on their dialogue maps. This study draws on these multiple data sources: pupils’ maps in Compendium, writings in science and reflective comments about the uses of mapping for writing. Our analysis highlights the diversity of ways, both successful and unsuccessful, in which dialogue mapping was used by these young teenagers
Charged Higgs boson contribution to scattering from low to ultrahigh energy in Higgs triplet model
We study the scattering from low to ultrahigh energy in the
framework of Higgs Triplet Model (HTM). We add the contribution of charged
Higgs boson exchange to the total cross section of the scattering. We obtain
the upper bound in this
process from low energy experiment. We show that by using the upper bound
obtained, the charged Higgs contribution can give enhancements to the total
cross section with respect to the SM prediction up to 5.16% at
eV and maximum at and would help to determine the
feasibility experiments to discriminate between SM and HTM at current available
facilities.Comment: 6 pages, 6 figure
Significant Biochemical, Biophysical and Metabolic Diversity in Circulating Human Cord Blood Reticulocytes
10.1371/journal.pone.0076062PLoS ONE810-POLN
Stratification of COPD patients by previous admission for targeting of preventative care
SummaryBackgroundHospital admissions for exacerbations of chronic obstructive pulmonary disease (COPD) impact considerably on disease evolution and healthcare provision. Building on previous studies, this study postulated that COPD patients could be stratified by risk of admission to determine which groups provide the greatest burden on resources, and how interventions should be targeted to prevent admissions.MethodsCOPD admissions during 1997–2003 in three Strategic Health Authorities in England were analysed (n=80,291). Patients admitted during winter (1 November–31 March) were stratified into three groups according to the number of admissions during the previous year: 0 (NIL), 1–2 (MOD) or ≥3 (FRQ). Winter weeks were classified as “average”, “above average”, “high”, or “very high” risk, compared with the long-term mean.ResultsThe risk of admission during winter for FRQ and MOD patients was 40% and 12% respectively. NIL patients contributed to 70% of winter admissions, and 90% of the variation between “average” and “very high” weeks, versus 9% and 1% for MOD and FRQ.ConclusionsPatients with no previous admissions have lower individual risk, but contribute to a high overall utilisation of health care resources and should be targeted to prevent admissions. Focusing upon high-risk patients (frequent attenders or more severe) may only reduce a small proportion of admissions, and therefore clinicians should ensure that all COPD patients receive appropriate therapy to reduce risk of exacerbations
Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
We have measured the beam-normal single-spin asymmetry in elastic scattering
of transversely-polarized 3 GeV electrons from unpolarized protons at Q^2 =
0.15, 0.25 (GeV/c)^2. The results are inconsistent with calculations solely
using the elastic nucleon intermediate state, and generally agree with
calculations with significant inelastic hadronic intermediate state
contributions. A_n provides a direct probe of the imaginary component of the
2-gamma exchange amplitude, the complete description of which is important in
the interpretation of data from precision electron-scattering experiments.Comment: 5 pages, 3 figures, submitted to Physical Review Letters; shortened
to meet PRL length limit, clarified some text after referee's comment
Strange Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment
We have measured parity-violating asymmetries in elastic electron-proton
scattering over the range of momentum transfers 0.12 < Q^2 < 1.0 GeV^2. These
asymmetries, arising from interference of the electromagnetic and neutral weak
interactions, are sensitive to strange quark contributions to the currents of
the proton. The measurements were made at JLab using a toroidal spectrometer to
detect the recoiling protons from a liquid hydrogen target. The results
indicate non-zero, Q^2 dependent, strange quark contributions and provide new
information beyond that obtained in previous experiments.Comment: 5 pages, 2 figure
The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles
In the G0 experiment, performed at Jefferson Lab, the parity-violating
elastic scattering of electrons from protons and quasi-elastic scattering from
deuterons is measured in order to determine the neutral weak currents of the
nucleon. Asymmetries as small as 1 part per million in the scattering of a
polarized electron beam are determined using a dedicated apparatus. It consists
of specialized beam-monitoring and control systems, a cryogenic hydrogen (or
deuterium) target, and a superconducting, toroidal magnetic spectrometer
equipped with plastic scintillation and aerogel Cerenkov detectors, as well as
fast readout electronics for the measurement of individual events. The overall
design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method
Untyped Recursion Schemes and Infinite Intersection Types
Abstract. A new framework for higher-order program verification has been recently proposed, in which higher-order functional programs are modelled as higher-order recursion schemes and then model-checked. As recursion schemes are essentially terms of the simply-typed lambda-calculus with recursion and tree constructors, however, it was not clear how the new framework applies to programs written in languages with more advanced type systems. To circumvent the limitation, this paper introduces an untyped version of recursion schemes and develops an in-finite intersection type system that is equivalent to the model checking of untyped recursion schemes, so that the model checking can be re-duced to type checking as in recent work by Kobayashi and Ong for typed recursion schemes. The type system is undecidable but we can obtain decidable subsets of the type system by restricting the shapes of intersection types, yielding a sound (but incomplete in general) model checking algorithm.
Meta-GWAS identifies the heritability of acute radiation-induced toxicities in head and neck cancer
Background and purpose: We aimed to the genetic components and susceptibility variants associated with acute radiation-induced toxicities (RITs) in patients with head and neck cancer (HNC). Materials and methods: We performed the largest meta-GWAS of seven European cohorts (n = 4,042). Patients were scored weekly during radiotherapy for acute RITs including dysphagia, mucositis, and xerostomia. We analyzed the effect of variants on the average burden (measured as area under curve, AUC) per each RIT, and standardized total average acute toxicity (STATacute) score using a multivariate linear regression. We tested suggestive variants (p < 1.0x10-5) in discovery set (three cohorts; n = 2,640) in a replication set (four cohorts; n = 1,402). We meta-analysed all cohorts to calculate RITs specific SNP-based heritability, and effect of polygenic risk scores (PRSs), and genetic correlations among RITS. Results: From 393 suggestive SNPs identified in discovery set; 37 were nominally significant (preplication < 0.05) in replication set, but none reached genome-wide significance (pcombined < 5 × 10-8). In-silico functional analyses identified “3′-5'-exoribonuclease activity” (FDR = 1.6e-10) for dysphagia, “inositol phosphate-mediated signalling” for mucositis (FDR = 2.20e-09), and “drug catabolic process” for STATacute (FDR = 3.57e-12) as the most enriched pathways by the RIT specific suggestive genes. The SNP-based heritability (±standard error) was 29 ± 0.08 % for dysphagia, 9 ± 0.12 % (mucositis) and 27 ± 0.09 % (STATacute). Positive genetic correlation was rg = 0.65 (p = 0.048) between dysphagia and STATacute. PRSs explained limited variation of dysphagia (3 %), mucositis (2.5 %), and STATacute (0.4 %). Conclusion: In HNC patients, acute RITs are modestly heritable, sharing 10 % genetic susceptibility, when PRS explains < 3 % of their variance. We identified numerus suggestive SNPs, which remain to be replicated in larger studies
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