Current guidelines identify people with chronic kidney disease (CKD) as being at high risk for cardiovascular and all-cause mortality. Because as many as 19 million Americans may have CKD, a comprehensive summary of this risk would be potentially useful for planning public health policy. A systematic review of the association between non-dialysis-dependent CKD and the risk for all-cause and cardiovascular mortality was conducted. Patient-and study-related characteristics that influenced the magnitude of these associations also were investigated. MEDLINE and EMBASE databases were searched, and reference lists through December 2004 were consulted. Authors of 10 primary studies provided additional data. Cohort studies or cohort analyses of randomized, controlled trials that compared mortality between those with and without chronically reduced kidney function were included. Studies were excluded from review when participants were followed for <1 yr or had ESRD. Two reviewers independently extracted data on study setting, quality, participant and renal function characteristics, and outcomes. Thirty-nine studies that followed a total of 1,371,990 participants were reviewed. The unadjusted relative risk for mortality in participants with reduced kidney function compared with those without ranged from 0.94 to 5.0 and was significantly more than 1.0 in 93% of cohorts. Among the 16 studies that provided suitable data, the absolute risk for death increased exponentially with decreasing renal function. Fourteen cohorts described the risk for mortality from reduced kidney function, after adjustment for other established risk factors. Although adjusted relative hazards were consistently lower than unadjusted relative risks (median reduction 17%), they remained significantly more than 1.0 in 71% of cohorts. This review supports current guidelines that identify individuals with CKD as being at high risk for cardiovascular mortality. Determining which interventions best offset this risk remains a health priority. I t has been known for many years that ESRD is associated with very high mortality and accelerated cardiovascular disease (1). Several recent studies suggest that the risk for death is increased independently in individuals who have less severe impairment of kidney function and are not dialysis dependent, compared with those who have preserved kidney function (2,3). However, other rigorously conducted studies have found little or no significant increase in all-cause or cardiovascular mortality in the setting of mild to moderate chronic kidney disease (CKD) (4,5). Even among studies that have demonstrated higher mortality rates in people with CKD, the magnitude of the increased risk has varied substantially for reasons that are unclear.Current guidelines identify individuals with CKD as being at high risk for cardiovascular disease and other adverse outcomes (6). Because non-dialysis-dependent CKD may affect as many as 19 million Americans (7), a summary of the risk for all-cause and cardiovascular mortality associated w...
Abstract. A comprehensive ring current model (CRCM) has been developed that couples the Rice Convection Model (RCM) and the kinetic model of Fok and coworkers. The coupled model is able to simulate, for the first time using a self-consistently calculated electric field, the evolution of an inner magnetosphere plasma distribution that conserves the first two adiabatic invariants. The traditional RCM calculates the ionospheric electric fields and currents consistent with a magnetospheric ion distribution that is assumed to be isotropic in pitch angle. The Fok model calculates the plasma distribution by solving the Boltzmann equation with specified electric and magnetic fields. To combine the RCM and the Fok model, the RCM Birkeland current algorithm has been generalized to arbitrary pitch angle distributions. Given a specification of height-integrated ionospheric conductance, the RCM component of the CRCM computes the ionospheric electric field and currents. The Fok model then advances the ring current plasma distribution using the electric field computed by the RCM and at the same time calculates losses along particle drift paths. We present the logic of CRCM and the first validation results following the H + distribution during the previously studied magnetic storm of May 2, 1986. The H + fluxes calculated by the coupled model agree very well with observations by AMPTE/CCE. In particular, the coupled model is able to reproduce the high H + flux seen on the dayside at L -2.3 that the previous simulation, which employed a Stern-Volland convection model with shielding factor 2, failed to produce. Though the Stern-Volland and CRCM electric fields differ in several respects, the most notable difference is that the CRCM predicts strong electric fields near Earth in the storm main phase, particularly in the dusk-midnight quadrant. Thus the CRCM injects particles more deeply and more quickly.
[1] A data-driven physical model of the energetic electrons in the Earth's radiation belts, called the Radiation Belt Environment (RBE) model, has been developed to understand Earth's radiation belt dynamics and to predict the radiation conditions found there. This model calculates radiation belt electron fluxes from 10 keV to 6 MeV in the inner magnetosphere. It takes into account the realistic, time-varying magnetic field and considers effects of wave-particle interactions with whistler mode chorus waves. The storm on 23-27 October 2002 is simulated and the temporal evolutions of the radial and pitch angle distributions of energetic electrons are examined. The calculated electron fluxes agree very well with particle data from the low-orbit SAMPEX and LANL geosynchronous satellites, when the wave-particle interactions are taken into account during storm recovery. Flux increases begin near the plasmapause and then diffuse outward to higher L shells, consistent with previous findings from statistical studies. A simplified version of the RBE model is now running in real time to provide nowcasting of the radiation belt environment. With further improvements and refinements, this model will have important value in both scientific and space weather applications.
Simulation studies of the Earth's radiation belts and ring current are very useful in understanding the acceleration, transport, and loss of energetic particles. Recently, the Comprehensive Ring Current Model (CRCM) and the Radiation Belt Environment (RBE) model were merged to form a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. CIMI solves for many essential quantities in the inner magnetosphere, including ion and electron distributions in the ring current and radiation belts, plasmaspheric density, Region 2 currents, convection potential, and precipitation in the ionosphere. It incorporates whistler mode chorus and hiss wave diffusion of energetic electrons in energy, pitch angle, and cross terms. CIMI thus represents a comprehensive model that considers the effects of the ring current and plasmasphere on the radiation belts. We have performed a CIMI simulation for the storm on 5-9 April 2010 and then compared our results with data from the Two Wide-angle Imaging Neutral-atom Spectrometers and Akebono satellites. We identify the dominant energization and loss processes for the ring current and radiation belts. We find that the interactions with the whistler mode chorus waves are the main cause of the flux increase of MeV electrons during the recovery phase of this particular storm. When a self-consistent electric field from the CRCM is used, the enhancement of MeV electrons is higher than when an empirical convection model is applied. We also demonstrate how CIMI can be a powerful tool for analyzing and interpreting data from the new Van Allen Probes mission.
[1] The local time distribution of the ring current in the 27-119 keV range during several geomagnetic storm main phases have been investigated. The data was obtained by the high energy neutral atom (HENA) imager onboard IMAGE. Global proton distributions are derived from the observed energetic neutral atom (ENA) images using a linear inversion technique. During storms with low IMF B y the peak of the proton distribution is around 01 MLT. For storms with high IMF B y the peak can rotate to dawn. The rotation angle depends on solar wind velocity and interplanetary magnetic field (IMF) B y , but less on IMF B z . We discuss how this morphology implies the existence of strong and skewed equatorial electric fields in the inner magnetosphere. Our results are consistent with in-situ ring current measurements, radar observations and with kinetic models that self-consistently calculate the electric field produced by the closure of the partial ring current.
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