3,548 research outputs found
Cosmological Bounds on Spatial Variations of Physical Constants
We derive strong observational limits on any possible large-scale spatial
variation in the values of physical 'constants' whose space-time evolution is
driven by a scalar field. The limits are imposed by the isotropy of the
microwave background on large angular scales in theories which describe space
and time variations in the fine structure constant, the electron-proton mass
ratio, and the Newtonian gravitational constant, G. Large-scale spatial
fluctuations in the fine structure constant are bounded by 2x10^-9 and
1.2x10^-8 in the BSBM and VSL theories respectively, fluctuations in the
electron-proton mass ratio by 9x10^-5 in the BM theory and fluctuations in G by
3.6x10^-10 in Brans-Dicke theory. These derived bounds are significantly
stronger than any obtainable by direct observations of astrophysical objects at
the present time.Comment: 13 pages, 1 table, typos corrected, refs added. Published versio
Patient safety incident capture resulting from incident reports: a comparative observational analysis
BACKGROUND: Patient safety incident (PSI) discovery is an essential component of quality improvement. When submitted, incident reports may provide valuable opportunities for PSI discovery. However, little objective information is available to date to quantify or demonstrate this value. The objective of this investigation was to assess how often Emergency Department (ED) incident reports submitted by different sources led to the discovery of PSIs.
METHODS: A standardized peer review process was implemented to evaluate all incident reports submitted to the ED. Findings of the peer review analysis were recorded prospectively in a quality improvement database. A retrospective analysis of the quality improvement database was performed to calculate the PSI capture rates for incident reports submitted by different source groups.
RESULTS: 363 incident reports were analyzed over a period of 18 months; 211 were submitted by healthcare providers (HCPs) and 126 by non-HCPs. PSIs were identified in 108 resulting in an overall capture rate of 31%. HCP-generated reports resulted in a 44% capture rate compared to 10% for non-HCPs (p \u3c 0.001). There was no difference in PSI capture between sub-groups of HCPs and non-HCPs.
CONCLUSION: HCP-generated ED incident reports were much more likely to capture PSIs than reports submitted by non-HCPs. However, HCP reports still led to PSI discovery less than half the time. Further research is warranted to develop effective strategies to improve the utility of incident reports from both HCPs and non-HCPs
Direct observation of the formation of polar nanoregions in Pb(MgNb)O using neutron pair distribution function analysis
Using neutron pair distribution function (PDF) analysis over the temperature
range from 1000 K to 15 K, we demonstrate the existence of local polarization
and the formation of medium-range, polar nanoregions (PNRs) with local
rhombohedral order in a prototypical relaxor ferroelectric
Pb(MgNb)O. We estimate the volume fraction of the PNRs as a
function of temperature and show that this fraction steadily increases from 0 %
to a maximum of 30% as the temperature decreases from 650 K to 15 K.
Below T200 K the PNRs start to overlap as their volume fraction reaches
the percolation threshold. We propose that percolating PNRs and their
concomitant overlap play a significant role in the relaxor behavior of
Pb(MgNb)O.Comment: 4 pages, 3 figure
Studying changes in the practice of two teachers developing assessment for learning
This paper describes changes in the practice of two teachers, observed over an eighteen month period, who were participating in a study intended to support teachers in developing their use of assessment in support of learning. The design of the intervention allowed each teacher to choose for themselves which aspects of their practice to develop. Analysis of lesson observations, journal entries and interviews indicate that both teachers were keen to change their practice, but were concerned about the disruption to their established routines, and in particular about the potential for loss of control of their classes. Both teachers did effect significant changes in their classrooms, but these tended to be developments of existing preferred ways of working, rather than radical innovations. In conclusion, it is suggested that to be most effective, teacher professional development needs to be structured strongly enough to afford teacher growth, but flexible enough to allow different teachers to take their practice in different ways
Emergency department patient safety incident characterization: an observational analysis of the findings of a standardized peer review process
BACKGROUND: Emergency Department (ED) care has been reported to be prone to patient safety incidents (PSIs). Improving our understanding of PSIs is essential to prevent them. A standardized, peer review process was implemented to identify and analyze ED PSIs. The primary objective of this investigation was to characterize ED PSIs identified by the peer review process. A secondary objective was to characterize PSIs that led to patient harm. In addition, we sought to provide a detailed description of the peer review process for others to consider as they conduct their own quality improvement initiatives.
METHODS: An observational study was conducted in a large, urban, tertiary-care ED. Over a two-year period, all ED incident reports were investigated via a standardized, peer review process. PSIs were identified and analyzed for contributing factors including systems failures and practitioner-based errors. The classification system for factors contributing to PSIs was developed based on systems previously reported in the emergency medicine literature as well as the investigators\u27 experience in quality improvement and peer review. All cases in which a PSI was discovered were further adjudicated to determine if patient harm resulted.
RESULTS: In 24 months, 469 cases were investigated, identifying 152 PSIs. In total, 188 systems failures and 96 practitioner-based errors were found to have contributed to the PSIs. In twelve cases, patient harm was determined to have resulted from PSIs. Systems failures were identified in eleven of the twelve cases in which a PSI resulted in patient harm.
CONCLUSION: Systems failures were almost twice as likely as practitioner-based errors to contribute to PSIs, and systems failures were present in the majority of cases resulting in patient harm. To effectively reduce PSIs, ED quality improvement initiatives should focus on systems failure reduction
Properties of Active Galaxies Deduced from H I Observations
We completed a new survey for H I emission for a large, well-defined sample
of 154 nearby (z < 0.1) galaxies with type 1 AGNs. We make use of the extensive
database presented in a companion paper to perform a comprehensive appraisal of
the cold gas content in active galaxies and to seek new strategies to
investigate the global properties of the host galaxies and their relationship
to their central black holes (BHs). We show that the BH mass obeys a strong,
roughly linear relation with the host galaxy's dynamical mass. BH mass follows
a looser, though still highly significant, correlation with the maximum
rotation velocity of the galaxy, as expected from the known scaling between
rotation velocity and central velocity dispersion. Neither of these H I-based
correlations is as tight as the more familiar relations between BH mass and
bulge luminosity or velocity dispersion, but they offer the advantage of being
insensitive to the glare of the nucleus and therefore are promising new tools
for probing the host galaxies of both nearby and distant AGNs. We present
evidence for substantial ongoing BH growth in the most actively accreting AGNs.
In these nearby systems, BH growth appears to be delayed with respect to the
assembly of the host galaxy but otherwise has left no detectable perturbation
to its mass-to-light ratio or its global gas content. The host galaxies of type
1 AGNs, including those luminous enough to qualify as quasars, are generally
gas-rich systems, possessing a cold interstellar medium reservoir at least as
abundant as that in inactive galaxies of the same morphological type. This
calls into question current implementations of AGN feedback in models of galaxy
formation that predict strong cold gas depletion in unobscured AGNs. (Abridged)Comment: To appear in ApJ; 14 page
Genomic insights into the rapid emergence and evolution of MDR in Staphylococcus pseudintermedius.
OBJECTIVES: MDR methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains have emerged rapidly as major canine pathogens and present serious treatment issues and concerns to public health due to their, albeit low, zoonotic potential. A further understanding of the genetics of resistance arising from a broadly susceptible background of S. pseudintermedius is needed. METHODS: We sequenced the genomes of 12 S. pseudintermedius isolates of varied STs and resistance phenotypes. RESULTS: Nine distinct clonal lineages had acquired either staphylococcal cassette chromosome (SCC) mec elements and/or Tn5405-like elements carrying up to five resistance genes [aphA3, sat, aadE, erm(B), dfrG] to generate MRSP, MDR methicillin-susceptible S. pseudintermedius and MDR MRSP populations. The most successful and clinically problematic MDR MRSP clones, ST68 SCCmecV(T) and ST71 SCCmecII-III, have further accumulated mutations in gyrA and grlA conferring resistance to fluoroquinolones. The carriage of additional mobile genetic elements (MGEs) was highly variable, suggesting that horizontal gene transfer is frequent in S. pseudintermedius populations. CONCLUSIONS: Importantly, the data suggest that MDR MRSP evolved rapidly by the acquisition of a very limited number of MGEs and mutations, and that the use of many classes of antimicrobials may co-select for the spread and emergence of MDR and XDR strains. Antimicrobial stewardship will need to be comprehensive, encompassing human medicine and veterinary disciplines to successfully preserve antimicrobial efficacy
Does menopause transition influence viral suppression and adherence in Women living with HIV?
BACKGROUND
Increasing numbers of women living with HIV transition through menopause. It is unclear if this transition has an impact on treatment adherence, viral suppression, psychiatric comorbidities or drug use. We aimed at examining adherence and viral suppression during the perimenopausal period and explored the influence of psychiatric comorbidities and active injection drug use (IDU).
SETTING
Retrospective Swiss HIV Cohort Study analysis from 01/2010 to 12/2018.
METHODS
We explored peri- and postmenopausal trends of viral blips, low-level viremia, viral failure, adherence, psychiatric comorbidities and IDU using interrupted time series (ITS) models.
RESULTS
Rates of depression and psychiatric care increased during perimenopause before decreasing afterwards. Negative treatment outcomes such as viral blips, low-level viremia, viral failure and low adherence steadily declined while transitioning through menopause - this was also true for subgroups of women with depression, psychiatric treatment and active IDU.
CONCLUSIONS
Increased rates of depression and psychiatric care while transitioning through menopause do not result in lower rates of adherence or viral suppression in women living with HIV in Switzerland
Potential Energy Surface for H_2 Dissociation over Pd(100)
The potential energy surface (PES) of dissociative adsorption of H_2 on
Pd(100) is investigated using density functional theory and the full-potential
linear augmented plane wave (FP-LAPW) method. Several dissociation pathways are
identified which have a vanishing energy barrier. A pronounced dependence of
the potential energy on ``cartwheel'' rotations of the molecular axis is found.
The calculated PES shows no indication of the presence of a precursor state in
front of the surface. Both results indicate that steering effects determine the
observed decrease of the sticking coefficient at low energies of the H_2
molecules. We show that the topology of the PES is related to the dependence of
the covalent H(s)-Pd(d) interactions on the orientation of the H_2 molecule.Comment: RevTeX, 8 pages, 5 figures in uufiles forma
Effects of uniaxial strain in LaMnO_3
The effects of uniaxial strain on the structural, orbital, optical, and
magnetic properties of LaMnO_3 are calculated using a general elastic energy
expression, along with a tight-binding parameterization of the band theory.
Tensile uniaxial strain of the order of 2 % (i.e., of the order of magnitude of
those induced in thin films by lattice mismatch with substrates) is found to
lead to changes in the magnetic ground state, leading to dramatic changes in
the band structure and optical conductivity spectrum. The magnetostriction
effect associated with the Neel transition of bulk(unstrained) LaMnO_3 is also
determined. Due to the Jahn-Teller coupling, the uniform tetragonal distortion
mode is softer in LaMnO_3 than in doped cubic manganates. Reasons why the
observed (\pi \pi 0) orbital ordering is favored over a (\pi \pi \pi)
periodicity are discussed.Comment: 9 figures, submitted in Phys. Rev.
- …