9,959 research outputs found
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Accuracy of medical billing data against the electronic health record in the measurement of colorectal cancer screening rates.
ObjectiveMedical billing data are an attractive source of secondary analysis because of their ease of use and potential to answer population-health questions with statistical power. Although these datasets have known susceptibilities to biases, the degree to which they can distort the assessment of quality measures such as colorectal cancer screening rates are not widely appreciated, nor are their causes and possible solutions.MethodsUsing a billing code database derived from our institution's electronic health records, we estimated the colorectal cancer screening rate of average-risk patients aged 50-74 years seen in primary care or gastroenterology clinic in 2016-2017. 200 records (150 unscreened, 50 screened) were sampled to quantify the accuracy against manual review.ResultsOut of 4611 patients, an analysis of billing data suggested a 61% screening rate, an estimate that matches the estimate by the Centers for Disease Control. Manual review revealed a positive predictive value of 96% (86%-100%), negative predictive value of 21% (15%-29%) and a corrected screening rate of 85% (81%-90%). Most false negatives occurred due to examinations performed outside the scope of the database-both within and outside of our institution-but 21% of false negatives fell within the database's scope. False positives occurred due to incomplete examinations and inadequate bowel preparation. Reasons for screening failure include ordered but incomplete examinations (48%), lack of or incorrect documentation by primary care (29%) including incorrect screening intervals (13%) and patients declining screening (13%).ConclusionsBilling databases are prone to substantial bias that may go undetected even in the presence of confirmatory external estimates. Caution is recommended when performing population-level inference from these data. We propose several solutions to improve the use of these data for the assessment of healthcare quality
Shifting Patterns of Nitrogen Excretion and Amino Acid Catabolism Capacity during the Life Cycle of the Sea Lamprey (\u3cem\u3ePetromyzon mariunus\u3c/em\u3e)
The jawless fish, the sea lamprey (Petromyzon marinus), spends part of its life as a burrow-dwelling, suspension-feeding larva (ammocoete) before undergoing a metamorphosis into a free swimming, parasitic juvenile that feeds on the blood of fishes. We predicted that animals in this juvenile, parasitic stage have a great capacity for catabolizing amino acids when large quantities of protein-rich blood are ingested. The sixfold to 20-fold greater ammonia excretion rates (JAmm) in postmetamorphic (nonfeeding) and parasitic lampreys compared with ammocoetes suggested that basal rates of amino acid catabolism increased following metamorphosis. This was likely due to a greater basal amino acid catabolizing capacity in which there was a sixfold higher hepatic glutamate dehydrogenase (GDH) activity in parasitic lampreys compared with ammocoetes. Immunoblotting also revealed that GDH quantity was 10-fold and threefold greater in parasitic lampreys than in ammocoetes and upstream migrant lampreys, respectively. Higher hepatic alanine and aspartate aminotransferase activities in the parasitic lampreys also suggested an enhanced amino acid catabolizing capacity in this life stage. In contrast to parasitic lampreys, the twofold larger free amino acid pool in the muscle of upstream migrant lampreys confirmed that this period of natural starvation is accompanied by a prominent proteolysis. Carbamoyl phosphate synthetase III was detected at low levels in the liver of parasitic and upstream migrant lampreys, but there was no evidence of extrahepatic (muscle, intestine) urea production via the ornithine urea cycle. However, detection of arginase activity and high concentrations of arginine in the liver at all life stages examined infers that arginine hydrolysis is an important source of urea. We conclude that metamorphosis is accompanied by a metabolic reorganization that increases the capacity of parasitic sea lampreys to catabolize intermittently large amino acid loads arising from the ingestion of protein rich blood from their prey/hosts. The subsequent generation of energy-rich carbon skeletons can then be oxidized or retained for glycogen and fatty acid synthesis, which are essential fuels for the upstream migratory and spawning phases of the sea lamprey’s life cycle
Anti-fouling surfaces:removal of micro-particles by magnetic artifical cilia,
Biological cilia are hair-like structures lining many biological surfaces. There are many examples in nature in which oscillating cilia efficiently manipulate particles in their vicinity, e.g. for feeding, anti-fouling or cell transport. In this paper, we experimentally demonstrate that surfaces covered with artificial cilia have the capacity to remove micro-particles from the ciliated area, creating a particle-free area. The artificial cilia used are micro-moulded magnetic artificial cilia (MAC), actuated externally by a homebuilt magnetic setup. The ciliated surface is capable of removing a large size range of particles except for particles which have a diameter that is similar to the cilia pitch. It is also able to remove irregular-shaped sand particles in both water and air. These findings can contribute to the development of novel particle manipulation and self-cleaning/ antifouling surfaces, which can find application in, for example, lab-on-a-chip devices and marine antifouling
Mass and dust in the disk of a spiral lens galaxy
Gravitational lensing is a potentially important probe of spiral galaxy
structure, but only a few cases of lensing by spiral galaxies are known. We
present Hubble Space Telescope and Magellan observations of the two-image
quasar PMN J2004-1349, revealing that the lens galaxy is a spiral galaxy. One
of the quasar images passes through a spiral arm of the galaxy and suffers 3
magnitudes of V-band extinction. Using simple lens models, we show that the
mass quadrupole is well-aligned with the observed galaxy disk. A more detailed
model with components representing the bulge and disk gives a bulge-to-disk
mass ratio of 0.16 +/- 0.05. The addition of a spherical dark halo, tailored to
produce an overall flat rotation curve, does not change this conclusion.Comment: ApJ, in press [9pp, 7 figs
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Co-Location of Air Capture, Subseafloor CO2 Sequestration, and Energy Production on the Kerguelen Plateau
Reducing atmospheric CO2 using a combination of air capture and offshore geological storage can address technical and policy concerns with climate mitigation. Because CO2 mixes rapidly in the atmosphere, air capture could operate anywhere and in principle reduce CO2 to preindustrial levels. We investigate the Kerguelen plateau in the Indian Ocean, which offers steady wind resources, vast subseafloor storage capacities, and minimal risk of economic damages or human inconvenience and harm. The efficiency of humidity swing driven air capture under humid and windy conditions is tested in the laboratory. Powered by wind, we estimate 75 Mt CO2/yr could be collected using air capture and sequestered below seafloor or partially used for synfuel. Our analysis suggests that Kerguelen offers a remote and environmentally secure location for CO2 sequestration using renewable energy. Regional reservoirs could hold over 1500 Gt CO2, sequestering a large fraction of 21st century emissions
Sauter-Schwinger like tunneling in tilted Bose-Hubbard lattices in the Mott phase
We study the Mott phase of the Bose-Hubbard model on a tilted lattice. On the
(Gutzwiller) mean-field level, the tilt has no effect -- but quantum
fluctuations entail particle-hole pair creation via tunneling. For small
potential gradients (long-wavelength limit), we derive a quantitative analogy
to the Sauter-Schwinger effect, i.e., electron-positron pair creation out of
the vacuum by an electric field. For large tilts, we obtain resonant tunneling
related to Bloch oscillations.Comment: 4 pages, 1 figur
Validation of the TOLNet lidars: The Southern California Ozone Observation Project (SCOOP)
The North America-based Tropospheric Ozone Lidar Network (TOLNet) was recently established to provide high spatiotemporal vertical profiles of ozone, to better understand physical processes driving tropospheric ozone variability and to validate the tropospheric ozone measurements of upcoming spaceborne missions such as Tropospheric Emissions: Monitoring Pollution (TEMPO). The network currently comprises six tropospheric ozone lidars, four of which are mobile instruments deploying to the field a few times per year, based on campaign and science needs. In August 2016, all four mobile TOLNet lidars were brought to the fixed TOLNet site of JPL Table Mountain Facility for the 1-week-long Southern California Ozone Observation Project (SCOOP). This intercomparison campaign, which included 400¿h of lidar measurements and 18 ozonesonde launches, allowed for the unprecedented simultaneous validation of five of the six TOLNet lidars. For measurements between 3 and 10¿km¿a.s.l., a mean difference of 0.7¿ppbv (1.7¿%), with a root-mean-square deviation of 1.6¿ppbv or 2.4¿%, was found between the lidars and ozonesondes, which is well within the combined uncertainties of the two measurement techniques. The few minor differences identified were typically associated with the known limitations of the lidars at the profile altitude extremes (i.e., first 1¿km above ground and at the instruments' highest retrievable altitude). As part of a large homogenization and quality control effort within the network, many aspects of the TOLNet in-house data processing algorithms were also standardized and validated. This thorough validation of both the measurements and retrievals builds confidence as to the high quality and reliability of the TOLNet ozone lidar profiles for many years to come, making TOLNet a valuable ground-based reference network for tropospheric ozone profiling.Peer ReviewedPostprint (published version
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