4,504 research outputs found
Infarction of the Duodenum
On Dec. 18, 1953, a five-year-old Brown Swiss cow was admitted to the Stange Memorial Clinic. The patient had previously been examined by the ambulatory clinicians, at which time she had shown few diagnostic symptoms. She was positive to the electronic metal detector test and was sent to the clinic as a hardware suspect
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Detection of human influence on a new, validated 1500-Year temperature reconstruction
Climate records over the last millennium place the twentieth-century warming in a longer historical context. Reconstructions of millennial temperatures show a wide range of variability, raising questions about the reliability of currently available reconstruction techniques and the uniqueness of late-twentieth-century warming. A calibration method is suggested that avoids the loss of low-frequency variance. A new reconstruction using this method shows substantial variability over the last 1500 yr. This record is consistent with independent temperature change estimates from borehole geothermal records, compared over the same spatial and temporal domain. The record is also broadly consistent with other recent reconstructions that attempt to fully recover low-frequency climate variability in their central estimate. High variability in reconstructions does not hamper the detection of greenhouse gas-induced climate change, since a substantial fraction of the variance in these reconstructions from the beginning of the analysis in the late thirteenth century to the end of the records can be attributed to external forcing. Results from a detection and attribution analysis show that greenhouse warming is detectable in all analyzed high-variance reconstructions (with the possible exception of one ending in 1925), and that about a third of the warming in the first half of the twentieth century can be attributed to anthropogenic greenhouse gas emissions. The estimated magnitude of the anthropogenic signal is consistent with most of the warming in the second half of the twentieth century being anthropogenic
Nonlinear Ionic Conductivity of Thin Solid Electrolyte Samples: Comparison between Theory and Experiment
Nonlinear conductivity effects are studied experimentally and theoretically
for thin samples of disordered ionic conductors. Following previous work in
this field the {\it experimental nonlinear conductivity} of sodium ion
conducting glasses is analyzed in terms of apparent hopping distances. Values
up to 43 \AA are obtained. Due to higher-order harmonic current density
detection, any undesired effects arising from Joule heating can be excluded.
Additionally, the influence of temperature and sample thickness on the
nonlinearity is explored. From the {\it theoretical side} the nonlinear
conductivity in a disordered hopping model is analyzed numerically. For the 1D
case the nonlinearity can be even handled analytically. Surprisingly, for this
model the apparent hopping distance scales with the system size. This result
shows that in general the nonlinear conductivity cannot be interpreted in terms
of apparent hopping distances. Possible extensions of the model are discussed.Comment: 7 pages, 6 figure
A methodology review on the incremental prognostic value of computed tomography biomarkers in addition to Framingham risk score in predicting cardiovascular disease: the use of association, discrimination and reclassification
This is the final version of the article. Available from the publisher via the DOI in this record.BACKGROUND: Computed tomography (CT) biomarkers claim to improve cardiovascular risk stratification. This review
focuses on significant differences in incremental measures between adequate and inadequate reporting practise.
METHODS: Studies included were those that used Framingham Risk Score as a baseline and described the
incremental value of adding calcium score or CT coronary angiogram in predicting cardiovascular risk. Searches of
MEDLINE, EMBASE, Web of Science and Cochrane Central were performed with no language restriction.
RESULTS: Thirty five studies consisting of 206,663 patients (men = 118,114, 55.1%) were included. The baseline
Framingham Risk Score included the 1998, 2002 and 2008 iterations. Selective reporting, inconsistent reference
groupings and thresholds were found. Twelve studies (34.3%) had major and 23 (65.7%) had minor alterations and
the respective Δ AUC were significantly different (p = 0.015). When the baseline model performed well, the Δ AUC
was relatively lower with the addition of a CT biomarker (Spearman coefficient = − 0.46, p < 0.0001; n = 33; 76 pairs
of data). Other factors that influenced AUC performance included exploration of data analysis, calibration, validation,
multivariable and AUC documentation (all p < 0.05). Most studies (68.7%) that reported categorical NRI (n = 16; 46
pairs of data) subjectively drew strong conclusions along with other poor reporting practices. However, no
significant difference in values of NRI was found between adequate and inadequate reporting.
CONCLUSIONS: The widespread practice of poor reporting particularly association, discrimination, reclassification,
calibration and validation undermines the claimed incremental value of CT biomarkers over the Framingham Risk
Score alone. Inadequate reporting of discrimination inflates effect estimate, however, that is not necessarily the case
for reclassification.This research was funded by the National Insitute for Health Research (NIHR)
Collaboration for Leadership in Applied Health Research and Care South
West Peninsula (NIHR CLAHRC South West Peninsula)
Developing measures for valuing changes in biodiversity
This document reports the findings from the DEFRA funded research project 'Developing measures for valuing changes in biodiversity'. The aim of the research was to develop an appropriate framework that will enable cost-effective and robust valuations of the total economic value of changes to biodiversity in the UK countryside. The research involved a review of ecological and economic literature on the valuation of biodiversity changes. The information gathered from this review, along with the findings from a series of public focus groups and an expert review of valuation methodologies, were used to develop a suite of valuation instruments that were used to measure the economic value of different aspects of biodiversity. Contingent valuation and choice experiment studies were administered to households in Cambridgeshire and Northumberland, while valuation workshops were conducted in Northumberland only. The data from these studies were also used to test for benefits transfer
The effect of thermophoresis on the discharge parameters in complex plasma experiments
Thermophoresis is a tool often applied in complex plasma experiments. One of
the usual stated benefits over other experimental tools is that changes induced
by thermophoresis neither directly depend on, nor directly influence, the
plasma parameters. From electronic data, plasma emission profiles in the
sheath, and Langmuir probe data in the plasma bulk, we conclude that this
assumption does not hold. An important effect on the levitation of dust
particles in argon plasma is observed as well. The reason behind the changes in
plasma parameters seems to be the change in neutral atom density accompanying
the increased gas temperature while running at constant pressure.Comment: 14 pages, 12 figure
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
We propose a new approach to the problem of rapidity gap survival (RGS) in
the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson)
in double-gap exclusive diffractive pp scattering, pp -> p + (gap) + H + (gap)
+ p. It is based on the idea that hard and soft interactions proceed over
widely different time- and distance scales and are thus approximately
independent. The high-mass system is produced in a hard scattering process with
exchange of two gluons between the protons. Its amplitude is calculable in
terms of the gluon generalized parton distributions (GPDs) in the protons,
which can be measured in J/psi production in exclusive ep scattering. The hard
scattering process is modified by soft spectator interactions, which we
calculate in a model-independent way in terms of the pp elastic scattering
amplitude. Contributions from inelastic intermediate states are suppressed. A
simple geometric picture of the interplay of hard and soft interactions in
diffraction is obtained. The onset of the black-disk limit in pp scattering at
TeV energies strongly suppresses diffraction at small impact parameters and is
the main factor in determining the RGS probability. Correlations between hard
and soft interactions (e.g. due to scattering from the long-range pion field of
the proton, or due to possible short-range transverse correlations between
partons) further decrease the RGS probability. We also investigate the
dependence of the diffractive cross section on the transverse momenta of the
final-state protons ("diffraction pattern"). By measuring this dependence one
can perform detailed tests of the interplay of hard and soft interactions, and
even extract information about the gluon GPD in the proton. Such studies appear
to be feasible with the planned forward detectors at the LHC.Comment: 26 pages, 17 figures, uses revtex
Detection of small-molecule enzyme inhibitors with peptides isolated from phage-displayed combinatorial peptide libraries
AbstractBackground: The rapidly expanding list of pharmacologically important targets has highlighted the need for ways to discover new inhibitors that are independent of functional assays. We have utilized peptides to detect inhibitors of protein function. We hypothesized that most peptide ligands identified by phage display would bind to regions of biological interaction in target proteins and that these peptides could be used as sensitive probes for detecting low molecular weight inhibitors that bind to these sites.Results: We selected a broad range of enzymes as targets for phage display and isolated a series of peptides that bound specifically to each target. Peptide ligands for each target contained similar amino acid sequences and competition analysis indicated that they bound one or two sites per target. Of 17 peptides tested, 13 were found to be specific inhibitors of enzyme function. Finally, we used two peptides specific for Haemophilus influenzae tyrosyl-tRNA synthetase to show that a simple binding assay can be used to detect small-molecule inhibitors with potencies in the micromolar to nanomolar range.Conclusions: Peptidic surrogate ligands identified using phage display are preferentially targeted to a limited number of sites that inhibit enzyme function. These peptides can be utilized in a binding assay as a rapid and sensitive method to detect small-molecule inhibitors of target protein function. The binding assay can be used with a variety of detection systems and is readily adaptable to automation, making this platform ideal for high-throughput screening of compound libraries for drug discovery
A cascade of magnetic field induced spin transitions in LaCoO3
We present magnetization and magnetostriction studies of the insulating
perovskite LaCoO3 in magnetic fields approaching 100 T. In marked contrast with
expectations from single-ion models, the data reveal two distinct first-order
spin transitions and well-defined magnetization plateaux. The magnetization at
the higher plateau is only about half the saturation value expected for spin-1
Co3+ ions. These findings strongly suggest collective behavior induced by
strong interactions between different electronic -- and therefore spin --
configurations of Co3+ ions. We propose a model of these interactions that
predicts crystalline spin textures and a cascade of four magnetic phase
transitions at high fields, of which the first two account for the experimental
data.Comment: 5 pages + supplementary materials, 5 figure
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