17,798 research outputs found
Practical approach to diastolic dysfunction in light of the new guidelines and clinical applications in the operating room and in the intensive care
There is growing evidence both in the perioperative period and in the field of intensive care (ICU) on the association between left ventricular diastolic dysfunction (LVDD) and worse outcomes in patients. The recent American Society of Echocardiography and European Association of Cardiovascular Imaging joint recommendations have tried to simplify the diagnosis and the grading of LVDD. However, both an often unknown pre-morbid LV diastolic function and the presence of several confoundersāi.e., use of vasopressors, positive pressure ventilation, volume loadingāmake the proposed parameters difficult to interpret, especially in the ICU. Among the proposed parameters for diagnosis and grading of LVDD, the two tissue Doppler imaging-derived variables eā² and E/eā² seem most reliable. However, these are not devoid of limitations. In the present review, we aim at rationalizing the applicability of the recent recommendations to the perioperative and ICU areas, discussing the clinical meaning and echocardiographic findings of different grades of LVDD, describing the impact of LVDD on patientsā outcomes and providing some hints on the management of patients with LVDD
Left ventricular systolic function evaluated by strain echocardiography and relationship with mortality in patients with severe sepsis or septic shock. a systematic review and meta-analysis
Sepsis-induced myocardial dysfunction is associated with poor outcomes, but traditional measurements of systolic function such as left ventricular ejection fraction (LVEF) do not directly correlate with prognosis. Global longitudinal strain (GLS) utilizing speckle-tracking echocardiography (STE) could be a better marker of intrinsic left ventricular (LV) function, reflecting myocardial deformation rather than displacement and volume changes. We sought to investigate the prognostic value of GLS in patients with sepsis and/or septic shock
Clinical and financial consequences of setting up an asthma clinic at St. Lukeās Hospital
The effects of setting up an asthma clinic were assessed in an audit study. A comparison was made between the quality and quantity of medication used by patients before and after attending the asthma clinic. The number and severity of exacerbations during a six month period before and a six month period after attending were also assessed. The cost of treatment before and after was also calculated. In 14% of patients, occupational factors, drugs or underlying lung disease were significant contributors to asthma. The number of acute episodes of severe asthma were reduced from 98 to 47, with hospital admissions falling from 26 to 1. Pulmonary function (%FEV1) improved in the group as a whole with the number of patients having their best FEV above 80% improving from 44 to 71. In spite of the expense of high cost drugs and the running costs of the clinic there were substantial savings largely from the reduced number of hospital admissions. The calculated annual cost fell from Lm 22,769 to Lm 10,654.peer-reviewe
Random Filters for Compressive Sampling and Reconstruction
We propose and study a new technique for efficiently acquiring and reconstructing signals based on convolution with a fixed FIR filter having random taps. The method is designed for sparse and compressible signals, i.e., ones that are well approximated by a short linear combination of vectors from an orthonormal basis. Signal reconstruction involves a non-linear Orthogonal Matching Pursuit algorithm that we implement efficiently by exploiting the nonadaptive, time-invariant structure of the measurement process. While simpler and more efficient than other random acquisition techniques like Compressed Sensing, random filtering is sufficiently generic to summarize many types of compressible signals and generalizes to streaming and continuous-time signals. Extensive numerical experiments demonstrate its efficacy for acquiring and reconstructing signals sparse in the time, frequency, and wavelet domains, as well as piecewise smooth signals and Poisson processes
Spectral Consequences of Deviation from Spherical Composition Symmetry in Type Ia Supernovae
We investigate the prospects for constraining the maximum scale of clumping
in composition that is consistent with observed Type Ia supernova flux spectra.
Synthetic spectra generated without purely spherical composition symmetry
indicate that gross asymmetries make prominent changes to absorption features.
Motivated by this, we consider the case of a single unblended line forming in
an atmosphere with perturbations of different scales and spatial distributions.
Perturbations of about 1% of the area of the photodisk simply weaken the
absorption feature by the same amount independent of the line of sight.
Conversely, perturbations of about 10% of the area of the photodisk introduce
variation in the absorption depth which does depend on the line of sight. Thus,
1% photodisk area perturbations may be consistent with observed profile
homogeneity but 10% photodisk area perturbations can not. Based on this, we
suggest that the absence of significant variation in the depths of Si II 6355
absorption features in normal Type Ia spectra near maximum light indicates that
any composition perturbations in these events are quite small. This also
constrains future three-dimensional explosion models to produce ejecta profiles
with only small scale inhomogeneities.Comment: 11 pages, 6 figure
Experimental assessment of drag reduction by traveling waves in a turbulent pipe flow
We experimentally assess the capabilities of an active, open-loop technique
for drag reduction in turbulent wall flows recently introduced by Quadrio et
al. [J. Fluid Mech., v.627, 161, (2009)]. The technique consists in generating
streamwise-modulated waves of spanwise velocity at the wall, that travel in the
streamwise direction.
A proof-of-principle experiment has been devised to measure the reduction of
turbulent friction in a pipe flow, in which the wall is subdivided into thin
slabs that rotate independently in the azimuthal direction. Different speeds of
nearby slabs provide, although in a discrete setting, the desired streamwise
variation of transverse velocity.
Our experiment confirms the available DNS results, and in particular
demonstrates the possibility of achieving large reductions of friction in the
turbulent regime. Reductions up to 33% are obtained for slowly
forward-traveling waves; backward-traveling waves invariably yield drag
reduction, whereas a substantial drop of drag reduction occurs for waves
traveling forward with a phase speed comparable to the convection speed of
near-wall turbulent structures.
A Fourier analysis is employed to show that the first harmonics introduced by
the discrete spatial waveform that approximates the sinusoidal wave are
responsible for significant effects that are indeed observed in the
experimental measurements. Practical issues related to the physical
implementation of this control scheme and its energetic efficiency are briefly
discussed.Comment: Article accepted by Phys. Fluids. After it is published, it will be
found at http://pof.aip.or
High frequency dynamics in a monatomic glass
The high frequency dynamics of glassy Selenium has been studied by Inelastic
X-ray Scattering at beamline BL35XU (SPring-8). The high quality of the data
allows one to pinpoint the existence of a dispersing acoustic mode for
wavevectors () of nm, helping to clarify a previous
contradiction between experimental and numerical results. The sound velocity
shows a positive dispersion, exceeding the hydrodynamic value by 10%
at nm. The dependence of the sound attenuation
, reported for other glasses, is found to be the low- limit of a
more general law which applies also to the
higher region, where no longer holds.Comment: Phys. Rev. Lett. (Accepted
On the High--Velocity Ejecta of the Type Ia Supernova 1994D
Synthetic spectra generated with the parameterized supernova
synthetic-spectrum code SYNOW are compared to spectra of the Type Ia SN 1994D
that were obtained before the time of maximum brightness. Evidence is found for
the presence of two-component Fe II and Ca II features, forming in high
velocity ( \kms) and lower velocity ( \kms) matter.
Possible interpretations of these spectral splits, and implications for using
early--time spectra of SNe Ia to probe the metallicity of the progenitor white
dwarf and the nature of the nuclear burning front in the outer layers of the
explosion, are discussed.Comment: 15 pages, 3 figures, 3 tables, Astrophysical Journal, in pres
Discovery-led refinement in e-discovery investigations: sensemaking, cognitive ergonomics and system design.
Given the very large numbers of documents involved in e-discovery investigations, lawyers face a considerable challenge of collaborative sensemaking. We report findings from three workplace studies which looked at different aspects of how this challenge was met. From a sociotechnical perspective, the studies aimed to understand how investigators collectively and individually worked with information to support sensemaking and decision making. Here, we focus on discovery-led refinement; specifically, how engaging with the materials of the investigations led to discoveries that supported refinement of the problems and new strategies for addressing them. These refinements were essential for tractability. We begin with observations which show how new lines of enquiry were recursively embedded. We then analyse the conceptual structure of a line of enquiry and consider how reflecting this in e-discovery support systems might support scalability and group collaboration. We then focus on the individual activity of manual document review where refinement corresponded with the inductive identification of classes of irrelevant and relevant documents within a collection. Our observations point to the effects of priming on dealing with these efficiently and to issues of cognitive ergonomics at the humanācomputer interface. We use these observations to introduce visualisations that might enable reviewers to deal with such refinements more efficiently
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