174 research outputs found
Autoimmunity in transfusion babesiosis: a spectrum of clinical presentations.
Transfusion-acquired babesiosis can be an asymptomatic or self-limited febrile hemolytic illness in a healthy host. A persistent, relapsing, and/or fulminant course with the development of life-threatening complications may be seen in immunocompromised or splenectomized patients. As in malaria, erythrocyte parasitemia is often associated with nonimmune hemolysis, and can be treated with erythrocytapheresis. Just as warm autoantibodies have been reported in malaria infection, the development of autoantibody-mediated immune hemolysis has been reported in babesiosis. We treated a previously healthy male with multiple injuries from a motor vehicle accident necessitating massive transfusion. Late in the hospitalization, his blood smear revealed Babesia microti, confirmed by PCR study and serology. This was eventually traced to a unit of blood from an asymptomatic blood donor that was transfused during his initial trauma care. Specific antibiotic therapy was begun, and severe hemolysis from a high parasite burden required red blood cell exchange which led to rapid abatement of the hemolysis. He had a positive DAT (IgG with a pan-reactive eluate) but no serum autoantibody. This persisted for 10 days following cessation of hemolysis, and became negative while still on antibiotics while his parasite burden became undetectable. Reports of autoimmunity associated with community acquired babesiosis often have severe hemolysis from their autoantibodies, but our case shows that autoantibodies may also follow transfusion-acquired babesiosis. The nature of the autoantigen is unknown
Using Deep Space Climate Observatory Measurements to Study the Earth as An Exoplanet
Even though it was not designed as an exoplanetary research mission, the Deep
Space Climate Observatory (DSCOVR) has been opportunistically used for a novel
experiment, in which Earth serves as a proxy exoplanet. More than two years of
DSCOVR Earth images were employed to produce time series of multi-wavelength,
single-point light sources, in order to extract information on planetary
rotation, cloud patterns, surface type, and orbit around the Sun. In what
follows, we assume that these properties of the Earth are unknown, and instead
attempt to derive them from first principles. These conclusions are then
compared with known data about our planet. We also used the DSCOVR data to
simulate phase angle changes, as well as the minimum data collection rate
needed to determine the rotation period of an exoplanet. This innovative method
of using the time evolution of a multi-wavelength, reflected single-point light
source, can be deployed for retrieving a range of intrinsic properties of an
exoplanet around a distant star
First Top-Down Estimates of Anthropogenic NO_x Emissions Using High-Resolution Airborne Remote Sensing Observations
A number of satelliteâbased instruments have become an essential part of monitoring emissions. Despite sound theoretical inversion techniques, the insufficient samples and the footprint size of current observations have introduced an obstacle to narrow the inversion window for regional models. These key limitations can be partially resolved by a set of modest highâquality measurements from airborne remote sensing. This study illustrates the feasibility of nitrogen dioxide (NO_2) columns from the Geostationary Coastal and Air Pollution Events Airborne Simulator (GCAS) to constrain anthropogenic NO_x emissions in the HoustonâGalvestonâBrazoria area. We convert slant column densities to vertical columns using a radiative transfer model with (i) NO_2 profiles from a highâresolution regional model (1 Ă 1 km^2) constrained by Pâ3B aircraft measurements, (ii) the consideration of aerosol optical thickness impacts on radiance at NO_2 absorption line, and (iii) highâresolution surface albedo constrained by groundâbased spectrometers. We characterize errors in the GCAS NO_2 columns by comparing them to Pandora measurements and find a striking correlation (r > 0.74) with an uncertainty of 3.5 Ă 10^(15) molecules cm^(â2). On 9 of 10 total days, the constrained anthropogenic emissions by a Kalman filter yield an overall 2â50% reduction in polluted areas, partly counterbalancing the wellâdocumented positive bias of the model. The inversion, however, boosts emissions by 94% in the same areas on a day when an unprecedented local emissions event potentially occurred, significantly mitigating the bias of the model. The capability of GCAS at detecting such an event ensures the significance of forthcoming geostationary satellites for timely estimates of topâdown emissions
Randomised trials at the level of the individual
In global health research, short-term, small-scale clinical trials with fixed, two-arm trial designs that generally do not allow for major changes throughout the trial are the most common study design. Building on the introductory paper of this Series, this paper discusses data-driven approaches to clinical trial research across several adaptive trial designs, as well as the master protocol framework that can help to harmonise clinical trial research efforts in global health research. We provide a general framework for more efficient trial research, and we discuss the importance of considering different study designs in the planning stage with statistical simulations. We conclude this second Series paper by discussing the methodological and operational complexity of adaptive trial designs and master protocols and the current funding challenges that could limit uptake of these approaches in global health research
Method-specific and unexplained reactivity in automated solid-phase testing and their association with specific antibodies
Direct Sun measurements of NO_2 column abundances from Table Mountain, California: Intercomparison of low- and high-resolution spectrometers
The NO_2 total column abundance, C_(NO_2) was measured with a direct Sun viewing technique using three different instruments at NASA Jet Propulsion Laboratory's (JPL) Table Mountain Facility in California during an instrument intercomparison campaign in July 2007. The instruments are a highâresolution (âŒ0.001 nm) Fourier transform ultraviolet spectrometer (FTUVS) from JPL and two moderateâresolution grating spectrometers, multifunction differential optical absorption spectroscopy (MFâDOAS) (âŒ0.8 nm) from Washington State University and Pandora (âŒ0.4 nm) from NASA Goddard Space Flight Center. FTUVS uses high spectral resolution to determine the absolute NO_2 column abundance independently from the exoatmospheric solar irradiance using rovibrational NO_2 absorption lines. The NO_2 total column is retrieved after removing the solar background using Dopplerâshifted spectra from the east and west limbs of the Sun. The FTUVS measurements were used to validate the independently calibrated measurements of multifunction differential optical absorption spectroscopy (MFâDOAS) and Pandora. The latter two instruments start with measured highâSun spectra as solar references to retrieve relative NO_2 columns and then apply modified Langley or âbootstrapâ methods to determine the amounts of NO_2 in the references to obtain the absolute NO_2 columns. The calibration offset derived from the FTUVS measurements is consistent with the values derived from Langley and bootstrap calibration plots of the NO_2 slant column measured by the grating spectrometers. The calibrated total vertical column abundances of NO_2, C_(NO_2) from all three instruments are compared showing that MFâDOAS and Pandora data agree well with each other, and both data sets agree with FTUVS data to within (1.5 ± 4.1)% and (6.0 ± 6.0)%, respectively
Relationship Between Column-Density and Surface Mixing Ratio: Statistical Analysis of O3 and NO2 Data from the July 2011 Maryland DISCOVER-AQ Mission
To investigate the ability of column (or partial column) information to represent surface air quality, results of linear regression analyses between surface mixing ratio data and column abundances for O3 and NO2 are presented for the July 2011 Maryland deployment of the DISCOVER-AQ mission. Data collected by the P-3B aircraft, ground-based Pandora spectrometers, Aura/OMI satellite instrument, and simulations for July 2011 from the CMAQ air quality model during this deployment provide a large and varied data set, allowing this problem to be approached from multiple perspectives. O3 columns typically exhibited a statistically significant and high degree of correlation with surface data (R(sup 2) > 0.64) in the P- 3B data set, a moderate degree of correlation (0.16 < R(sup 2) < 0.64) in the CMAQ data set, and a low degree of correlation (R(sup 2) < 0.16) in the Pandora and OMI data sets. NO2 columns typically exhibited a low to moderate degree of correlation with surface data in each data set. The results of linear regression analyses for O3 exhibited smaller errors relative to the observations than NO2 regressions. These results suggest that O3 partial column observations from future satellite instruments with sufficient sensitivity to the lower troposphere can be meaningful for surface air quality analysis
Using Deep Space Climate Observatory Measurements to Study the Earth as an Exoplanet
Even though it was not designed as an exoplanetary research mission, the Deep Space Climate Observatory (DSCOVR) has been opportunistically used for a novel experiment in which Earth serves as a proxy exoplanet. More than 2 yr of DSCOVR Earth images were employed to produce time series of multiwavelength, single-point light sources in order to extract information on planetary rotation, cloud patterns, surface type, and orbit around the Sun. In what follows, we assume that these properties of the Earth are unknown and instead attempt to derive them from first principles. These conclusions are then compared with known data about our planet. We also used the DSCOVR data to simulate phase-angle changes, as well as the minimum data collection rate needed to determine the rotation period of an exoplanet. This innovative method of using the time evolution of a multiwavelength, reflected single-point light source can be deployed for retrieving a range of intrinsic properties of an exoplanet around a distant star
- âŠ