Late diagnosis of abdominal aortic aneurysms substantiates underutilization of abdominal aortic aneurysm screening for Medicare beneficiaries

ObjectiveAbdominal aortic aneurysm (AAA) screening remains largely underutilized in the U.S., and it is likely that the proportion of patients with aneurysms requiring prompt treatment is much higher compared with well-screened populations. The goals of this study were to determine the proportion of AAAs that required prompt repair after diagnostic abdominal imaging for U.S. Medicare beneficiaries and to identify patient and hospital factors contributing to early vs late diagnosis of AAA.MethodsData were extracted from Medicare claims records for patients at least 65 years old with complete coverage for 2 years who underwent intact AAA repair from 2006 to 2009. Preoperative ultrasound and computed tomography was tabulated from 2002 to repair. We defined early diagnosis of AAA as a patient with a time interval of greater than 6 months between the first imaging examination and the index procedure, and late diagnosis as patients who underwent the index procedure within 6 months of the first imaging examination.ResultsOf 17,626 patients who underwent AAA repair, 14,948 met inclusion criteria. Mean age was 77.5 ± 6.1 years. Early diagnosis was identified for 60.6% of patients receiving AAA repair, whereas 39.4% were repaired after a late diagnosis. Early diagnosis rates increased from 2006 to 2009 (59.8% to 63.4%; P < .0001) and were more common for intact repair compared with repair after rupture (62.9% vs 35.1%; P < .0001) and for women compared with men (66.3% vs 59.0%; P < .0001). On multivariate analysis, repair of intact vs ruptured AAAs (odds ratio, 3.1; 95% confidence interval, 2.7-3.6) and female sex (odds ratio, 1.4; 95% confidence interval, 1.3-1.5) remained the strongest predictors of surveillance. Although intact repairs were more likely to be diagnosed early, over one-third of patients undergoing repair for ruptured AAAs received diagnostic abdominal imaging greater than 6 months prior to surgery.ConclusionsDespite advances in screening practices, significant missed opportunities remain in the U.S. Medicare population for improving AAA care. It remains common for AAAs to be diagnosed when they are already at risk for rupture. In addition, a significant proportion of patients with early imaging rupture prior to repair. Our findings suggest that improved mechanisms for observational management are needed to ensure optimal preoperative care for patients with AAAs

Series expansion for a stochastic sandpile

Using operator algebra, we extend the series for the activity density in a one-dimensional stochastic sandpile with fixed particle density p, the first terms of which were obtained via perturbation theory [R. Dickman and R. Vidigal, J. Phys. A35, 7269 (2002)]. The expansion is in powers of the time; the coefficients are polynomials in p. We devise an algorithm for evaluating expectations of operator products and extend the series to O(t^{16}). Constructing Pade approximants to a suitably transformed series, we obtain predictions for the activity that compare well against simulations, in the supercritical regime.Comment: Extended series and improved analysi

Space Flight Qualification on a Multi-Fiber Ribbon Cable and Array Connector Assembly

NASA's Goddard Space Flight Center (GSFC) cooperatively with Sandia National Laboratories completed a series of tests on three separate configurations of multi-fiber ribbon cable and MTP connector assemblies. These tests simulate the aging process of components during launch and long-term space environmental exposure. The multi-fiber ribbon cable assembly was constructed of non-outgassing materials, with radiation-hardened, graded index 100/140-micron optical fiber. The results of this characterization presented here include vibration testing, thermal vacuum monitoring, and extended radiation exposure testing data

2007 Annual progress report synopsis of the Center for Structures of Membrane Proteins

A synopsis of the 2007 annual progress report for the Center for Structures of Membrane Proteins, a specialized center of the Protein Structure Initiative

L-Edge Spectroscopy of Dilute, Radiation-Sensitive Systems Using a Transition-Edge-Sensor Array

We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100-2000eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by conventional grating-based spectrometers. These results show that soft X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry and catalysis. In particular, TES spectrometers have a unique ability to characterize frozen solutions of radiation- and temperature-sensitive samples.Comment: 19 pages, 4 figure

ROTATIONAL-DYNAMICS OF SOLID C-70 - A NEUTRON-SCATTERING STUDY

PMID: 10011126PMID: 10011126 This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K.PMID: 10011126 This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K.PMID: 10011126 This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K.We report the results of neutron-diffraction and low-energy neutron-inelastic-scattering experiments on high-purity solid C-70 between 10 and 640 K. Thermal hysteresis effects are found to accompany structural changes both on cooling and on heating. The observed diffuse scattering intensity does not change with temperature. At 10 K broad librational peaks are observed at 1.82(16) meV [full width at half maximum=1.8(5) meV]. The peaks soften and broaden further with increasing temperature. At and above room temperature, they collapse into a single quasielastic line. At 300 K, the diffusive reorientational motion appears to be somewhat anisotropic, becoming less so with increasing temperature. An isotropic rotational diffusion model, in which the motions of adjacent molecules are uncorrelated, describes well the results at 525 K. The temperature dependence of the rotational diffusion constants is consistent with a thermally activated process having an activation energy of 32(7) meV.This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K

Asymptotic behavior of the order parameter in a stochastic sandpile

We derive the first four terms in a series for the order paramater (the stationary activity density rho) in the supercritical regime of a one-dimensional stochastic sandpile; in the two-dimensional case the first three terms are reported. We reorganize the pertubation theory for the model, recently derived using a path-integral formalism [R. Dickman e R. Vidigal, J. Phys. A 35, 7269 (2002)], to obtain an expansion for stationary properties. Since the process has a strictly conserved particle density p, the Fourier mode N^{-1} psi_{k=0} -> p, when the number of sites N -> infinity, and so is not a random variable. Isolating this mode, we obtain a new effective action leading to an expansion for rho in the parameter kappa = 1/(1+4p). This requires enumeration and numerical evaluation of more than 200 000 diagrams, for which task we develop a computational algorithm. Predictions derived from this series are in good accord with simulation results. We also discuss the nature of correlation functions and one-site reduced densities in the small-kappa (large-p) limit.Comment: 18 pages, 5 figure

NASA Standing Review Board Handbook

No abstract availabl

Geographic Variation in Salt Marsh Structure and Function for Nekton: a Guide to Finding Commonality Across Multiple Scales

Coastal salt marshes are distributed widely across the globe and are considered essential habitat for many fish and crustacean species. Yet, the literature on fishery support by salt marshes has largely been based on a few geographically distinct model systems, and as a result, inadequately captures the hierarchical nature of salt marsh pattern, process, and variation across space and time. A better understanding of geographic variation and drivers of commonalities and differences across salt marsh systems is essential to informing future management practices. Here, we address the key drivers of geographic variation in salt marshes: hydroperiod, seascape configuration, geomorphology, climatic region, sediment supply and riverine input, salinity, vegetation composition, and human activities. Future efforts to manage, conserve, and restore these habitats will require consideration of how environmental drivers within marshes affect the overall structure and subsequent function for fisheries species. We propose a future research agenda that provides both the consistent collection and reporting of sources of variation in small-scale studies and collaborative networks running parallel studies across large scales and geographically distinct locations to provide analogous information for data poor locations. These comparisons are needed to identify and prioritize restoration or conservation efforts, identify sources of variation among regions, and best manage fisheries and food resources across the globe