897 research outputs found
Detecting BS in Health Care 2.0
In our initial report âDetecting BS in Health Care,â we identified our top ten BS concepts and trends within the health care industry, and encouraged our readers to hone their âBS detection skills.â Many of you have let us know that we âleft some BS on the table.â For example, there are more Old English terms for BS that we missedâsuch as babble, bafflegab, bilge, blather, blarney, boshâand these are just from the bâs. This time around we make bolder assertions about other possible forms of BSâincluding some sacred cowsâthat might make some readers uncomfortable
Accountable Care Organizations: Back to the Future?
Accountable Care Organizations (ACOs) are networks of providers that assume risk for the quality and total cost of the care they deliver. Public policymakers and private insurers hope that ACOs will achieve the elusive âtriple aimâ of improving quality of care, improving population health, and reducing costs. The model is still evolving, but the premise is that ACOs will accomplish these aims by coordinating care, managing chronic disease, and aligning financial incentives for hospitals and physicians. If this sounds familiar, it may be because the integrated care networks of the 1990s tried some of the same things, and mostly failed in their attempts. This Issue Brief summarizes the similarities and differences between the new ACOs and the integrated delivery networks of the 1990s, and presents the authorsâ analysis of the likely success of these new organizations in affecting the costs and quality of health care
Characterization of Scattered Waves from Fractures by Estimating the Transfer Function Between Reflected Events Above and Below Each Interval
It is important to be able to detect and characterize naturally occurring fractures in reservoirs using surface seismic
reflection data. 3D finite difference elastic modeling is used to create simulated surface seismic data over a three layer model and a
five layer model. The elastic properties in the reservoir layer of each model are varied to simulate different amounts of vertical parallel
fracturing. The presence of the fractures induces ringing wave trains primarily at times later than the bottom reservoir reflection.
These ringy or scattered wave trains appear coherent on the seismograms recorded parallel to the fracture direction. While there are
many scattered events on the seismograms recorded perpendicular to the direction of the fractures, these events appear to generally
stack out during conventional processing.
A method of characterizing and detecting scattering in intervals is developed by deconvolution to give an interval transfer
function. The method is simple for the case of two isolated reflections, one from the top of the reservoir and the other from the bottom
of the reservoir. The transfer function is computed using the top reflection as the input and the bottom reflection as the output. The
transfer function then characterizes the effect of the scattering layer. A simple pulse shape indicates no scattering. A long ringy
transfer function captures the scattering within the reservoir interval. When analyzing field data, it is rarely possible to isolate
reflections. Therefore, an adaptation of the method is developed using autocorrelations of the wave trains above (as input) and below
(as output) the interval of interest for the deconvolution process. The presence of fractures should be detectable from observed ringy
transfer functions computed for each time interval. The fracture direction should be identifiable from azimuthal variations â there
should be more ringiness in the direction parallel to fracturing. The method applied to ocean bottom cable field data at 4 locations
show strong temporal and azimuthal variations of the transfer function which may be correlated to the known geology.Massachusetts Institute of Technology. Earth Resources LaboratoryUnited States. Dept. of Energy (Grant DE-FC26-02NT15346)Eni S.p.A. (Firm
Fracture Density Estimation Using Spectral Analysis of Reservoir Reflections: A Numerical Modeling Approach
We use a 3-D finite difference numerical model to generate synthetic seismograms from a simple fractured reservoir
containing evenly spaced, discrete, vertical fractures. The fractures are represented using a single column of
anisotropic grid points. Analysis of seismic amplitudes and spectral characteristics were carried out on the top and
base reservoir reflections as well as scattered wave coda for models with fracture spacing ranging from 0.01 to 0.1
fractures/m. Results show that the bulk scattered wave energy contained in a common shot gather increases greatly
when the fracture spacing is greater than about 1/4 wavelength. Wavenumber spectra for integrated amplitude
versus offset from a time window containing the base reservoir reflector show spectral peaks corresponding to the
fracture spacing.United States. Dept. of Energy (Grant DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources LaboratoryEni S.p.A. (Firm
Complementary effects of extracellular nucleotides and platelet-derived extracts on angiogenesis of vasa vasorum endothelial cells in vitro and subcutaneous Matrigel plugs in vivo
Spatial Orientation And Distribution Of Reservoir Fractures From Scattered Seismic Energy
Shortened title: Fracture characterization from coda wavesWe present the details of a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations we have made from 3D finite difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fractures impart a ringing coda type signature to any seismic energy which is transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: 1) the difference in angle between the orientation of the fractures and the acquisition direction, 2) the fracture spacing, 3) the wavelength of the illuminating seismic energy, and 4) the compliance, or stiffness, of the fractures. This coda energy is the most coherent when the acquisition direction is parallel to the strike of the fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. Our method uses surface seismic reflection traces to derive a transfer function which quantifies the change in an apparent source wavelet before and after propagating through a fractured interval. The transfer function for an interval with no or low amounts of scattering will be more spike-like and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. When a 3D survey is acquired with a full range of azimuths, the variation in the derived transfer functions allows us to identify subsurface areas with high fracturing and determine the strike of those fractures. We calibrated the method with model data and then applied it to the Emilio field with a fractured reservoir giving results which agree with known field measurements and previously published fracture orientations derived from PS anisotropy.Eni S.p.A. (Firm)United States. Dept. of Energy (Grant number DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources Laborator
Drivers of the changing abundance of European birds at two spatial scales
Detecting biodiversity change and identifying its causes is challenging because biodiversity is multifaceted and temporal data often contain bias. Here, we model temporal change in species' abundance and biomass by using extensive data describing the population sizes and trends of native breeding birds in the United Kingdom (UK) and the European Union (EU). In addition, we explore how speciesâ population trends vary with speciesâ traits. We demonstrate significant change in the bird assemblages of the UK and EU, with substantial reductions in overall bird abundance and losses concentrated in a relatively small number of abundant and smaller sized species. In contrast, rarer and larger birds had generally fared better. Simultaneously, overall avian biomass had increased very slightly in the UK and was stable in the EU, indicating a change in community structure. Abundance trends across species were positively correlated with speciesâ body mass and with trends in climate suitability, and varied with speciesâ abundance, migration strategy, and niche associations linked to diet. Our work highlights how changes in biodiversity cannot be captured easily by a single number; care is required when measuring and interpreting biodiversity change given that different metrics can provide very different insight
The Dust Trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006
We report on observations of the dust trail of comet
67P/Churyumov-Gerasimenko (CG) in visible light with the Wide Field Imager at
the ESO/MPG 2.2m telescope at 4.7 AU before aphelion, and at 24 micron with the
MIPS instrument on board the Spitzer Space Telescope at 5.7 AU both before and
after aphelion. The comet did not appear to be active during our observations.
Our images probe large dust grains emitted from the comet that have a radiation
pressure parameter beta<0.01. We compare our observations with simulated images
generated with a dynamical model of the cometary dust and constrain the
emission speeds, size distribution, production rate and geometric albedo of the
dust. We achieve the best fit to our data with a differential size distribution
exponent of -4.1, and emission speeds for a beta=0.01 particle of 25 m/s at
perihelion and 2 m/s at 3 AU. The dust production rate in our model is on the
order of 1000 kg/s at perihelion and 1 kg/s at 3 AU, and we require a dust
geometric albedo between 0.022 and 0.044. The production rates of large (>10
micron) particles required to reproduce the brightness of the trail are
sufficient to also account for the coma brightness observed while the comet was
inside 3 AU, and we infer that the cross-section in the coma of CG may be
dominated by grains of the order of 60-600 micron.Comment: 79 pages, 13 figures, 6 tables. Accepted for publication in Icaru
Androgens Regulate Prostate Cancer Cell Growth via an AMPK-PGC-1?-Mediated Metabolic Switch
Prostate cancer is the most commonly diagnosed malignancy among men in industrialized countries, accounting for the second leading cause of cancer-related deaths. While we now know that the androgen receptor (AR) is important for progression to the deadly advanced stages of the disease, it is poorly understood what AR-regulated processes drive this pathology. Here, we demonstrate that AR regulates prostate cancer cell growth via the metabolic sensor 5?-AMP-activated protein kinase (AMPK), a kinase that classically regulates cellular energy homeostasis. In patients, activation of AMPK correlated with prostate cancer progression. Using a combination of radiolabeled assays and emerging metabolomic approaches, we also show that prostate cancer cells respond to androgen treatment by increasing not only rates of glycolysis, as is commonly seen in many cancers, but also glucose and fatty acid oxidation. Importantly, this effect was dependent on androgen-mediated AMPK activity. Our results further indicate that the AMPK-mediated metabolic changes increased intracellular ATP levels and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1?)-mediated mitochondrial biogenesis, affording distinct growth advantages to the prostate cancer cells. Correspondingly, we used outlier analysis to determine that PGC-1? is overexpressed in a subpopulation of clinical cancer samples. This was in contrast to what was observed in immortalized benign human prostate cells and a testosterone-induced rat model of benign prostatic hyperplasia. Taken together, our findings converge to demonstrate that androgens can co-opt the AMPK-PGC-1? signaling cascade, a known homeostatic mechanism, to increase prostate cancer cell growth. The current study points to the potential utility of developing metabolic-targeted therapies directed towards the AMPK-PGC-1? signaling axis for the treatment of prostate cancer
A Neurodisparity Index of Nationwide Access to Neurological Health Care in Northern Ireland.
Nationwide disparities in managing neurological patients have rarely been reported. We compared neurological health care between the population who reside in a Health and Social Care Trust with a tertiary neuroscience center and those living in the four non-tertiary center Trusts in Northern Ireland. Using the tertiary center Trust population as reference, neurodisparity indices (NDIs) defined as the number of treated patients resident in each Trust per 100,000 residents compared to the same ratio in the tertiary center Trust for a fixed time period. NDIs were calculated for four neurological pathways-intravenous thrombolysis (iv-tPA) and mechanical thrombectomy (MT) for acute ischemic stroke (AIS), disease modifying treatment (DMT) in multiple sclerosis (MS) and admissions to a tertiary neurology ward. Neurological management was recorded in 3,026 patients. Patients resident in the tertiary center Trust were more likely to receive AIS treatments (iv-tPA and MT) and access to the neurology ward (p < 0.001) than patients residing in other Trusts. DMT use for patients with MS was higher in two non-tertiary center Trusts than in the tertiary center Trust. There was a geographical gradient for MT for AIS patients and ward admissions. Averaged NDIs for non-tertiary center Trusts were: 0.48 (95%CI 0.32-0.71) for patient admissions to the tertiary neurology ward, 0.50 (95%CI 0.38-0.66) for MT in AIS patients, 0.78 (95%CI 0.67-0.92) for iv-tPA in AIS patients, and 1.11 (95%CI 0.99-1.26) for DMT use in MS patients. There are important neurodisparities in Northern Ireland, particularly for MT and tertiary ward admissions. Neurologists and health service planners should be aware that geography and time-dependent management of neurological patients worsen neurodisparities
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