2,770 research outputs found
Optimising the conceptualisation of context; comment on "Stakeholder Perspectives of Attributes and Features of Context Relevant to Knowledge Translation in Health Settings: A Multi-Country Analysis"
Context matters. Therefore, efforts to develop greater conceptual clarity are important for science and practice. In this commentary, we outline some key issues that were prompted by Squire’s et al.’s contribution. Specifically, we reinforce context as an interactive concept and therefore something that is hard to ‘pin down’, the problematic nature of conceptualising context in implementation and de-implementation, and a requirement for the development of culturally sensitive understandings. Finally, we suggest it is vital that continued investment into providing a more comprehensive list of determinants needs to be accompanied by an equal effort in developing practical methods and tools to support use and application
What can management theories offer evidence-based practice? A comparative analysis of measurement tools for organisational context
Background:
Given the current emphasis on networks as vehicles for innovation and change in health service delivery, the ability to conceptualise and measure organisational enablers for the social construction of knowledge merits attention. This study aimed to develop a composite tool to measure the organisational context for evidence-based practice (EBP) in healthcare.
Methods:
A structured search of the major healthcare and management databases for measurement tools from four domains: research utilisation (RU), research activity (RA), knowledge management (KM), and organisational learning (OL). Included studies were reports of the development or use of measurement tools that included organisational factors. Tools were appraised for face and content validity, plus development and testing methods. Measurement tool items were extracted, merged across the four domains, and categorised within a constructed framework describing the absorptive and receptive capacities of organisations.
Results:
Thirty measurement tools were identified and appraised. Eighteen tools from the four domains were selected for item extraction and analysis. The constructed framework consists of seven categories relating to three core organisational attributes of vision, leadership, and a learning culture, and four stages of knowledge need, acquisition of new knowledge, knowledge sharing, and knowledge use. Measurement tools from RA or RU domains had more items relating to the categories of leadership, and acquisition of new knowledge; while tools from KM or learning organisation domains had more items relating to vision, learning culture, knowledge need, and knowledge sharing. There was equal emphasis on knowledge use in the different domains.
Conclusion:
If the translation of evidence into knowledge is viewed as socially mediated, tools to measure the organisational context of EBP in healthcare could be enhanced by consideration of related concepts from the organisational and management sciences. Comparison of measurement tools across domains suggests that there is scope within EBP for supplementing the current emphasis on human and technical resources to support information uptake and use by individuals. Consideration of measurement tools from the fields of KM and OL shows more content related to social mechanisms to facilitate knowledge recognition, translation, and transfer between individuals and groups
HST Paschen alpha and 1.9 micron imaging of Sgr A West
We present HST/NICMOS images at 0.2" resolution of the HI Paschen Alpha (PaA)
emission line in a 70" x 90" region of the Galactic center centered on the
non-thermal radio source Sgr A*. The majority of the emission arises from
ionized gas in the mini-spiral in the central parsec. PaA emission is also seen
from 26 stellar sources, presumably early-type stars with mass-loss winds. The
new data reveal significant small-scale structure (<1"~0.04pc) in the ionized
gas of the mini-spiral; low surface brightness emission features are also seen
for the first time. Extinction, estimated from the ratio of observed PaA
emission to 6-cm continuum emission, varies from 20 to 50 mag with a median
Av=31.1 mag, in excellent agreement with earlier estimates for the stellar
sources and indepedent measurements derived using H92alpha recombination line
data. Large increases in extinction are seen along the periphery of the ionized
gas, suggesting that the ionized gas is partially extincted by dust in the
molecular clouds at the outside of the ionized regions. The small-scale,
filamentary structures in the ionized gas have a free thermal expansion time of
only ~ 3000 yrs; either magnetic fields or mass-loss winds from the hot
emission line stars may contain the ionized filaments. For both the ionized gas
and the stellar continuum, the centroids of the emission remain within ~+/- 1"
from a radius of 2" out to 40", providing further evidence that Sgr A* is
indeed at or extremely close to the dynamical center of the Galactic nucleus
stellar distribution. The 1.9 micron surface brightness increases inwards to
0.9" and then decreases or levels off closer to Sgr A*, possibly indicating the
core radius of the central stellar distribution or depletion of the late-type
stars by stellar collisions near the central black hole.Comment: 43 pages, 15 figures, 2 tables; Accepted to ApJ (9/1/03 issue
Resource based view of the firm as a theoretical lens on the organisational consequences of quality improvement
Evaluating the investment that healthcare organisations make in quality improvement requires knowledge of impact
at multiple levels, including patient care, workforce and other organisational resources. The degree to which these
resources help organisations to survive and thrive in the challenging contexts in which healthcare is designed and
delivered is unknown. Investigating this question from the perspective of the Resource Based View (RBV) of the Firm
may provide insights, although is not without challenge
Complete replication of hepatitis C virus in cell culture.
Many aspects of the hepatitis C virus (HCV) life cycle have not been reproduced in cell culture, which has slowed research progress on this important human pathogen. Here, we describe a full-length HCV genome that replicates and produces virus particles that are infectious in cell culture (HCVcc). Replication of HCVcc was robust, producing nearly 10(5) infectious units per milliliter within 48 hours. Virus particles were filterable and neutralized with a monoclonal antibody against the viral glycoprotein E2. Viral entry was dependent on cellular expression of a putative HCV receptor, CD81. HCVcc replication was inhibited by interferon-alpha and by several HCV-specific antiviral compounds, suggesting that this in vitro system will aid in the search for improved antivirals
Navigating the structural landscape of de Novo α-helical bundles
The
association of amphipathic α helices in water leads to
α-helical-bundle protein structures. However, the driving force
for thisthe hydrophobic effectis not specific and
does not define the number or the orientation of helices in the associated
state. Rather, this is achieved through deeper sequence-to-structure
relationships, which are increasingly being discerned. For example,
for one structurally extreme but nevertheless ubiquitous class of
bundlethe α-helical coiled coilsrelationships
have been established that discriminate between all-parallel dimers,
trimers, and tetramers. Association states above this are known, as
are antiparallel and mixed arrangements of the helices. However, these
alternative states are less well understood. Here, we describe a synthetic-peptide
system that switches between parallel hexamers and various up–down–up–down
tetramers in response to single-amino-acid changes and solution conditions.
The main accessible states of each peptide variant are characterized
fully in solution and, in most cases, to high resolution with X-ray
crystal structures. Analysis and inspection of these structures helps
rationalize the different states formed. This navigation of the structural
landscape of α-helical coiled coils above the dimers and trimers
that dominate in nature has allowed us to design rationally a well-defined
and hyperstable antiparallel coiled-coil tetramer (apCC-Tet). This
robust de novo protein provides another scaffold for further structural
and functional designs in protein engineering and synthetic biology
De novo protein design:How do we expand into the universe of possible protein structures?
Protein scientists are paving the way to a new phase in protein design and engineering. Approaches and methods are being developed that could allow the design of proteins beyond the confines of natural protein structures. This possibility of designing entirely new proteins opens new questions: What do we build? How do we build into protein-structure space where there are few, if any, natural structures to guide us? To what uses can the resulting proteins be put? And, what, if anything, does this pursuit tell us about how natural proteins fold, function and evolve? We describe the origins of this emerging area of fully de novo protein design, how it could be developed, where it might lead, and what challenges lie ahead
Inheritance of Evolved Glyphosate Resistance in a North Carolina Palmer Amaranth ( Amaranthus palmeri
Inheritance of glyphosate resistance in a Palmer amaranth biotype from North Carolina was studied. Glyphosate rates for 50% survival of glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes were 1288 and 58 g ha−1, respectively. These values for F1 progenies obtained from reciprocal crosses (GR×GS and GS×GR were 794 and 501 g ha−1, respectively. Dose response of F1 progenies indicated that resistance was not fully dominant over susceptibility. Lack of significant differences between dose responses for reciprocal F1 families suggested that genetic control of glyphosate resistance was governed by nuclear genome. Analysis of F1 backcross (BC1F1) families showed that 10 and 8 BC1F1 families out of 15 fitted monogenic inheritance at 2000 and 3000 g ha−1 glyphosate, respectively. These results indicate that inheritance of glyphosate resistance in this biotype is incompletely dominant, nuclear inherited, and might not be consistent with a single gene mechanism of inheritance. Relative 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) copy number varied from 22 to 63 across 10 individuals from resistant biotype. This suggested that variable EPSPS copy number in the parents might be influential in determining if inheritance of glyphosate resistance is monogenic or polygenic in this biotype
Lesion topography and microscopic white matter tract damage contribute to cognitive impairment in symptomatic carotid artery disease
Purpose: To investigate associations between neuroimaging markers of cerebrovascular disease, including lesion topography and extent and severity of strategic and global cerebral tissue injury, and cognition in carotid artery disease (CAD).
Materials and Methods: All participants gave written informed consent to undergo brain magnetic resonance imaging and the Addenbrooke’s Cognitive Examination–Revised. One hundred eight patients with symptomatic CAD but no dementia were included, and a score less than 82 represented cognitive impairment. Group comparison and interrelations between global cognitive and fluency performance, lesion topography, and ultrastructural damage were assessed with voxel-based statistics. Associations between cognition, medial temporal lobe atrophy (MTA), lesion volumes, and global white matter ultrastructural damage indexed as increased mean diffusivity were tested with regression analysis by controlling for age. Diagnostic accuracy of imaging markers selected from a multivariate prediction model was tested with receiver operating characteristic analysis.
Results: Cognitively impaired patients (n = 53 [49.1%], classified as having probable vascular cognitive disorder) were older than nonimpaired patients (P = .027) and had more frequent MTA (P<.001), more cortical infarctions (P = .016), and larger volumes of acute (P = .028) and chronic (P = .009) subcortical ischemic lesions. Lesion volumes did not correlate with global cognitive performance (lacunar infarctions, P = .060; acute lesions, P = .088; chronic subcortical ischemic lesions, P = .085). In contrast, cognitive performance correlated with presence of chronic ischemic lesions within the interhemispheric tracts and thalamic radiation (P< .05, false discovery rate corrected). Skeleton mean diffusivity showed the closest correlation with cognition (R2 = 0.311, P< .001) and promising diagnostic accuracy for vascular cognitive disorder (area under the curve, 0.82 [95% confidence interval: 0.75, 0.90]). Findings were confirmed in subjects with a low risk of preclinical Alzheimer disease indexed by the absence of MTA (n = 85).
Conclusion: Subcortical white matter ischemic lesion locations and severity of ultrastructural tract damage contribute to cognitive impairment in symptomatic CAD, which suggests that subcortical disconnection within large-scale cognitive neural networks is a key mechanism of vascular cognitive disorder
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