Search results for "SMAP"
showing 10 items of 37 documents
Validation of SMAP surface soil moisture products with core validation sites
2017
Abstract The NASA Soil Moisture Active Passive (SMAP) mission has utilized a set of core validation sites as the primary methodology in assessing the soil moisture retrieval algorithm performance. Those sites provide well-calibrated in situ soil moisture measurements within SMAP product grid pixels for diverse conditions and locations. The estimation of the average soil moisture within the SMAP product grid pixels based on in situ measurements is more reliable when location specific calibration of the sensors has been performed and there is adequate replication over the spatial domain, with an up-scaling function based on analysis using independent estimates of the soil moisture distributio…
Comparison of SMOS and SMAP soil moisture retrieval approaches using tower-based radiometer data over a vineyard field
2014
International audience; The objective of this study was to compare several approaches to soil moisture (SM) retrieval using l-band microwave radiometry. The comparison was based on a brightness temperature (TB) data set acquired since 2010 by the L-band radiometer ELBARA-II over a vineyard field at the Valencia Anchor Station (VAS) site. ELBARA-II, provided by the European Space Agency (ESA) within the scientific program of the SMOS (Soil Moisture and Ocean Salinity) mission, measures multiangular TB data at horizontal and vertical polarization for a range of incidence angles (30°–60°). Based on a three year data set (2010–2012), several SM retrieval approaches developed for spaceborne miss…
PHYSICS-based retrieval of scattering albedo and vegetation optical depth using multi-sensor data integration
2017
Vegetation optical depth and scattering albedo are crucial parameters within the widely used τ-ω model for passive microwave remote sensing of vegetation and soil. A multi-sensor data integration approach using ICESat lidar vegetation heights and SMAP radar as well as radiometer data enables a direct retrieval of the two parameters on a physics-derived basis. The crucial step within the retrieval methodology is the calculus of the vegetation scattering coefficient KS, where one exact and three approximated solutions are provided. It is shown that, when using the assumption of a randomly oriented volume, the backscatter measurements of the radar provide a sufficient first order estimate and …
Estimating Gravimetric Moisture of Vegetation Using an Attenuation-Based Multi-Sensor Approach
2018
Estimating parameters for global climate models via combined active and passive microwave remote sensing data has been a subject of intensive research in recent years. A variety of retrieval algorithms has been proposed for the estimation of soil moisture, vegetation optical depth and other parameters. A novel attenuation-based retrieval approach is proposed here to globally estimate the gravimetric moisture of vegetation (m g ) and retrieve information about the amount of water [kg] per amount of wet vegetation [kg]. The parameter m g is particularly interesting for agro-ecosystems, to assess the status of growing vegetation. The key feature of the proposed approach is that it relies on mu…
Analysis of the radar vegetation index and assessment of potential for improvement
2018
The Radar Vegetation Index (RVI) is widely applied to indicate vegetation cover. The index includes the backscattering intensities of co- and cross-polarization that do not only contain information coming from vegetation scattering at longer wavelength (L-band), but also from the soil underneath. A forward modelling approach using active and passive microwave-derived parameters to obtain the scattering contribution of the soil is pursued. The idea of this research study is a subtraction of the attenuated soil scattering contribution from the measured backscattering intensities, to provide a clean vegetation-based solution, called improved RVI (RVII). For latter analysis, the vegetation volu…
Therapeutic Plasmapheresis with Albumin Replacement in Alzheimer’s Disease and Chronic Progressive Multiple Sclerosis: A Review
2020
Background: Reducing the burden of beta-amyloid accumulation and toxic autoimmunity-related proteins, one of the recognized pathophysiological markers of chronic and common neurological disorders such as Alzheimer’s disease (AD) and multiple sclerosis (MS), may be a valid alternative therapy to reduce their accumulation in the brain and thus reduce the progression of these disorders. The objective of this review was to evaluate the efficacy of plasmapheresis (PP) in AD and chronic progressive MS patients (in terms of improving clinical symptoms) and to analyze its safety and protocols. Methods: Articles related to this topic and published without time limitations in the Medline, and C…
Anticoagulation with low-molecular-weight heparin (dalteparin) in plasmapheresis therapy: initial experience
2006
BACKGROUND: In contrast to other extracorporeal treatments no established regime exists for anticoagulation with low-molecular-weight heparin (LMWH) in plasmapheresis therapy. A study was conducted to investigate whether LMWH (dalteparin-Na) is suitable as an effective anticoagulant in plasmapheresis therapy. STUDY DESIGN AND METHODS: Eleven patients with autoimmune neurological diseases and the necessity for a plasmapheresis therapy were enrolled. A capillary membrane filter was used. A total of 2000 mL of human plasma was isovolumetrically exchanged per plasmapheresis cycle. The anticoagulation was accomplished with a single bolus of LMWH (dalteparin) of 80 to 90 IU per kg of body weigh…
Albumin versus solvent/detergent-treated pooled plasma as replacement fluid for long-term plasma exchange therapy in a patient with primary hypertrig…
2015
Chylomicronemia syndrome is a metabolic condition characterized by severe fasting hypertrigliceridemia (≥ 1000 mg/dL) and other clinical features including chronic abdominal pain and recurrent acute pancreatitis. In patients with acute or recurrent pancreatitis, plasma exchange (PEx) is indicated for the treatment of acute disease and prevention of recurrence. The use of plasma instead of albumin as replacement fluid has been suggested for its putative ability to replace the deficient enzyme possibly leading to better clinical improvement.A 40-year-old man with chylomicronemia syndrome due to a newly identified loss-of-function mutation in the lipoprotein lipase (LPL) gene (IVS2, c.250-1G/C…
Effectiveness of cascade filtration plasmapheresis in two patients affected by familial hypercholesterolemia
1995
Hypercholesterolemia has been recognised as a primary risk factor for coronary heart disease. Reduction of plasma levels of total and LDL cholesterol has been shown to decrease coronary atherosclerosis. Plasmapheresis represents an useful non-pharmacological tool to treat severe hypercholesterolemias. We have evaluated the effectiveness of a system of plasmapheresis using a cascade filtration method in two young male subjects (aged 16 and 26 years) with homozygous familial hypercholesterolemia. Both showed severe coronary atherosclerosis as determined by angiography. Procedures were performed at intervals of 7 days in each case. We observed a mean reduction of plasma levels of total cholest…
Relapsing and Progressive Complications of Severe Hypertriglyceridemia: Effective Long-Term Treatment with Double Filtration Plasmapheresis
2019
<b><i>Background:</i></b> Severe hypertriglyceridemia (HTG) is associated with major complications such as acute or relapsing pancreatitis (AP) and atherosclerotic cardiovascular disease (ASCVD). Rapid elimination of triglyceride (TG)-rich lipoproteins (LP) with double filtration plasmapheresis (DFPP) without need for substitution has been found to be effective for the acute, short-term treatment of HTG-induced AP. Data on the long-term use of DFPP to prevent HTG-associated complications are scarce. <b><i>Objectives:</i></b> To evaluate the use and efficacy of regular DFPP treatment in clinical practice for preventing recurrence of HTG-associa…