168 results on '"Donovan, David P."'
Search Results
2. ATLID Algorithms Applied to ALADIN
- Author
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Donovan, David P., primary, Zadelhoff, Gerd-Jan van, additional, Wang, Ping, additional, and Labzovskii, Lev, additional
- Published
- 2023
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- View/download PDF
3. Weighing the Giants V: Galaxy Cluster Scaling Relations
- Author
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Mantz, Adam B., Allen, Steven W., Morris, R. Glenn, von der Linden, Anja, Applegate, Douglas E., Kelly, Patrick L., Burke, David L., Donovan, David, and Ebeling, Harald
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We present constraints on the scaling relations of galaxy cluster X-ray luminosity, temperature and gas mass (and derived quantities) with mass and redshift, employing masses from robust weak gravitational lensing measurements. These are the first such results obtained from an analysis that simultaneously accounts for selection effects and the underlying mass function, and directly incorporates lensing data to constrain total masses. Our constraints on the scaling relations and their intrinsic scatters are in good agreement with previous studies, and reinforce a picture in which departures from self-similar scaling laws are primarily limited to cluster cores. However, the data are beginning to reveal new features that have implications for cluster astrophysics and provide new tests for hydrodynamical simulations. We find a positive correlation in the intrinsic scatters of luminosity and temperature at fixed mass, which is related to the dynamical state of the clusters. While the evolution of the nominal scaling relations over the redshift range $0.0
- Published
- 2016
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4. Yeast Expressing a Phage Endolysin Reduces Endogenous Clostridium perfringens Ex Vivo in 21-Day-Old Broiler Chicken Intestinal Fluids.
- Author
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Barnas, Michael R., Attuquayefio, Wendy D., Donovan, David M., Skory, Christopher D., Hammond, Rosemarie W., Siragusa, Gregory R., and Timmons, Jennifer R.
- Subjects
BROILER chickens ,YEAST ,SACCHAROMYCES cerevisiae ,INTESTINES ,ESCHERICHIA coli ,BACTERIOPHAGES ,CLOSTRIDIUM perfringens - Abstract
SUMMARY The phage endolysin PlyCP41 when purified from Escherichia coli exhibits lytic activity against Clostridium perfringens (CP) in vitro. The anti-clostridial activity of PlyCP41 endolysin expressed in transgenic yeast (Saccharomyces cerevisiae) was verified in phosphate buffered saline via mixing experiments with cultured CP and transgenic yeast slurries followed by serial dilution plating and colony counts on tryptose sulfite cycloserine (CP indicator) plates. The transgenic yeast containing PlyCP41 resulted in a log
10 4.5 reduction (99.997%; P < 0.01) of the cultured CP. In addition, this serial dilution plating assay was used to demonstrate that transgenic yeast slurries could reduce the endogenous CP content in fluids from three different gastrointestinal regions (proximal, medial, and distal) from 21-day-old broiler chickens. The transgenic yeast treatment of gut slurries resulted in a log10 1.19, 4.53, and 1.28 reduction in proximal, medial, and distal gut slurries (90% to 99.99% of the endogenous CP; P < 0.01), respectively, compared to nontreatment controls. These results indicate that the phage endolysin PlyCP41 expressed in S. cerevisiae is effective at reducing the endogenous CP in gastrointestinal fluids of broiler chickens. Future studies will measure the anti-CP effect in vivo by administering transgenic yeast to broiler chickens in the feed. RESUMEN Levadura que expresa una fago-endolisina reduce la presencia endógena de Clostridium perfringens Ex vivo en fluidos intestinales de pollos de engorde de 21 días. La fago endolisina PlyCP41, cuando se purifica a partir de Escherichia coli, exhibe actividad lítica contra Clostridium perfringens (Cp) in vitro. La actividad anticlostridial de la endolisina PlyCP41 expresada en levadura transgénica (Saccharomyces cerevisiae) se verificó en solución salina amortiguada con fosfato mediante experimentos de mezclas con cultivos de C. perfringens y suspensiones de levadura transgénica, seguido de cultivos de diluciones en serie y recuentos de colonias en placas de triptosa sulfito cicloserina (TSC; indicador para C. perfringens). La levadura transgénica que contenía PlyCP41 dio como resultado una reducción de log10 4.5 (99.997%; P <0.01) en el cultivo de C. perfringens. Además, este ensayo de dilución en serie en placas se utilizó para demostrar que las suspensiones de levadura transgénica podrían reducir el contenido de C. perfringens endógeno en fluidos de tres regiones gastrointestinales diferentes (proximal, medial y distal) de pollos de engorde de 21 días de edad. El tratamiento con levadura transgénica de las suspensiones intestinales dio como resultado una reducción de log10 de 1.19, 4.53 y 1.28 en las suspensiones intestinales proximal, medial y distal (90% a 99.99 % de C. perfringens endógena; P < 0.01), respectivamente, en comparación con los controles no tratados. Estos resultados indican que la fago-endolisina PlyCP41 expresada en S. cerevisiae es eficaz para reducir el contenido endógeno de C. perfringens en los fluidos gastrointestinales de pollos de engorde. Los estudios futuros medirán el efecto contra C. perfringens in vivo mediante la administración de levadura transgénica a pollos de engorde en el alimento. [ABSTRACT FROM AUTHOR]- Published
- 2024
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5. Cancellation of cloud shadow effects in the absorbing aerosol index retrieval algorithm of TROPOMI.
- Author
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Trees, Victor J. H., Wang, Ping, Stammes, Piet, Tilstra, Lieuwe G., Donovan, David P., and Siebesma, A. Pier
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BIG data ,AEROSOLS ,ALGORITHMS ,ALBEDO ,RADIATIVE transfer ,AIR quality ,PHASE-shifting interferometry - Abstract
Cloud shadows can be detected in the radiance measurements of the TROPOMI instrument on board the Sentinel-5P satellite due to its high spatial resolution, and could possibly affect its air quality products. The cloud shadow induced signatures are, however, not always apparent and may depend on various cloud and scene parameters. Hence, the quantification of the cloud shadow impact requires the analysis of large data sets. Here we use the cloud shadow detection algorithm DARCLOS to detect cloud shadow pixels in the TROPOMI absorbing aerosol index (AAI) product over Europe during 8 months. For every shadow pixel, we automatically select cloud- and shadow-free neighbour pixels, in order to estimate the cloud shadow induced signature. In addition, we simulate the measured cloud shadow impact on the AAI with our newly developed 3D radiative transfer algorithm MONKI. Both the measurements and simulations show that the average cloud shadow impact on the AAI is close to zero (0.06 and 0.16, respectively). However, the top-of-atmosphere reflectance ratio between 340 and 380 nm, which is used to compute the AAI, is significantly increased in 95 % of the shadow pixels. So, cloud shadows are bluer than surrounding non-shadow pixels. Our simulations explain that the traditional AAI formula intrinsically already corrects for this cloud shadow effect, via the lower retrieved scene albedo. This cancellation of cloud shadow signatures is not always perfect, sometimes yielding second order low and high biases in the AAI which we also successfully reproduce with our simulations. We show that the magnitude of those second order cloud shadow effects depends on various cloud parameters which are difficult to determine for the shadows measured with TROPOMI. We conclude that a potential cloud shadow correction strategy for the TROPOMI AAI would therefore be complicated if not unnecessary. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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6. Assessment of the spectral misalignment effect (SMILE) on EarthCARE's Multi-Spectral Imager aerosol and cloud property retrievals.
- Author
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Docter, Nicole, Hünerbein, Anja, Donovan, David P., Preusker, Rene, Fischer, Jürgen, Meirink, Jan Fokke, Stammes, Piet, and Eisinger, Michael
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AEROSOLS ,GAS absorption & adsorption ,SMILING ,ICE clouds ,WATER vapor ,WEATHER - Abstract
The Multi-Spectral Imager (MSI) on board the Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) will provide horizontal information about aerosols and clouds. These measurements are needed to extend vertical cloud and aerosol property information, which is obtained from EarthCARE's active sensors, in order to obtain a full three-dimensional view of cloud and aerosol conditions. Mesoscale weather systems, in particular, will be characterized. The discovery of a non-compliance of the MSI visible–near-infrared–shortwave infrared (VNS) camera's visible (VIS) and shortwave infrared (SWIR1) channels regarding a spectral central wavelength (CWVL) shift across-track of up to 14 nm (VIS) and 20 nm (SWIR1) led to the need for an analysis regarding its impact on MSI Level-2A aerosol and cloud products. A significant influence of the spectral misalignment effect (SMILE) on MSI retrievals is identified due to the spectral variation in gas absorption, surface reflectance, and aerosol and cloud properties within the spectral ranges of these MSI bands. For example, the VIS channel is positioned in close proximity to the red edge of green vegetation and is impacted by residual absorption of water vapor and ozone. Small central wavelength variations introduce uncertainties due to the rapid change in surface reflectance for conditions with low optical thickness. The present central wavelength shift in the VIS towards shorter wavelengths than at nadir introduces a relative error in transmission of up to 3.3 % due to the increasing influence of water vapor and ozone absorption. We found relative errors in the top-of-atmosphere (TOA) signal due to the SMILE of up to 30 % for low optical thickness over a land surface in that band. Since the magnitude of the impact strongly depends on the underlying surface and atmospheric conditions, we conclude that accounting for the SMILE in Level-2 retrievals or correcting the Level-1 signal will improve MSI aerosol and cloud product quality. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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7. The generation of EarthCARE L1 test data sets using atmospheric model data sets
- Author
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Donovan, David P., primary, Kollias, Pavlos, additional, Velázquez Blázquez, Almudena, additional, and van Zadelhoff, Gerd-Jan, additional
- Published
- 2023
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8. Numerical model generation of test frames for pre-launch studies of EarthCARE's retrieval algorithms and data management system
- Author
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Qu, Zhipeng, primary, Donovan, David P., additional, Barker, Howard W., additional, Cole, Jason N. S., additional, Shephard, Mark W., additional, and Huijnen, Vincent, additional
- Published
- 2023
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9. Robust Weak-lensing Mass Calibration of Planck Galaxy Clusters
- Author
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von der Linden, Anja, Mantz, Adam, Allen, Steven W., Applegate, Douglas E., Kelly, Patrick L., Morris, R. Glenn, Wright, Adam, Allen, Mark T., Burchat, Patricia R., Burke, David L., Donovan, David, and Ebeling, Harald
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
In light of the tension in cosmological constraints reported by the Planck team between their SZ-selected cluster counts and Cosmic Microwave Background (CMB) temperature anisotropies, we compare the Planck cluster mass estimates with robust, weak-lensing mass measurements from the Weighing the Giants (WtG) project. For the 22 clusters in common between the Planck cosmology sample and WtG, we find an overall mass ratio of $\left< M_{Planck}/M_{\rm WtG} \right> = 0.688 \pm 0.072$. Extending the sample to clusters not used in the Planck cosmology analysis yields a consistent value of $\left< M_{Planck}/M_{\rm WtG} \right> = 0.698 \pm 0.062$ from 38 clusters in common. Identifying the weak-lensing masses as proxies for the true cluster mass (on average), these ratios are $\sim 1.6\sigma$ lower than the default mass bias of 0.8 assumed in the Planck cluster analysis. Adopting the WtG weak-lensing-based mass calibration would substantially reduce the tension found between the Planck cluster count cosmology results and those from CMB temperature anisotropies, thereby dispensing of the need for "new physics" such as uncomfortably large neutrino masses (in the context of the measured Planck temperature anisotropies and other data). We also find modest evidence (at 95 per cent confidence) for a mass dependence of the calibration ratio and discuss its potential origin in light of systematic uncertainties in the temperature calibration of the X-ray measurements used to calibrate the Planck cluster masses. Our results exemplify the critical role that robust absolute mass calibration plays in cluster cosmology, and the invaluable role of accurate weak-lensing mass measurements in this regard., Comment: 5 pages, 2 figures
- Published
- 2014
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10. Weighing the Giants II: Improved Calibration of Photometry from Stellar Colors and Accurate Photometric Redshifts
- Author
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Kelly, Patrick L., von der Linden, Anja, Applegate, Douglas E., Allen, Mark T., Allen, Steven W., Burchat, Patricia R., Burke, David L., Ebeling, Harald, Capak, Peter, Czoske, Oliver, Donovan, David, Mantz, Adam, and Morris, R. Glenn
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We present improved methods for using stars found in astronomical exposures to calibrate both star and galaxy colors as well as to adjust the instrument flat field. By developing a spectroscopic model for the SDSS stellar locus in color-color space, synthesizing an expected stellar locus, and simultaneously solving for all unknown zeropoints when fitting to the instrumental locus, we increase the calibration accuracy of stellar locus matching. We also use a new combined technique to estimate improved flat-field models for the Subaru SuprimeCam camera, forming `star flats' based on the magnitudes of stars observed in multiple positions or through comparison with available SDSS magnitudes. These techniques yield galaxy magnitudes with reliable color calibration (< 0.01 - 0.02 mag accuracy) that enable us to estimate photometric redshift probability distributions without spectroscopic training samples. We test the accuracy of our photometric redshifts using spectroscopic redshifts z_s for ~5000 galaxies in 27 cluster fields with at least five bands of photometry, as well as galaxies in the COSMOS field, finding sigma((z_p - z_s)/(1 + z_s)) ~ 0.03 for the most probable redshift z_p. We show that the full posterior probability distributions for the redshifts of galaxies with five-band photometry exhibit good agreement with redshifts estimated from thirty-band photometry in the COSMOS field. The growth of shear with increasing distance behind each galaxy cluster shows the expected redshift-distance relation for a flat Lambda-CDM cosmology. Photometric redshifts and calibrated colors are used in subsequent papers to measure the masses of 51 galaxy clusters from their weak gravitational shear. We make our Python code for stellar locus matching available at http://big-macs-calibrate.googlecode.com; the code requires only a catalog and filter functions., Comment: Accepted by MNRAS with only minor revisions. Code available: http://big-macs-calibrate.googlecode.com (v2 latex symbols removed from abstract)
- Published
- 2012
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11. Weighing the Giants - I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster images
- Author
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von der Linden, Anja, Allen, Mark T., Applegate, Douglas E., Kelly, Patrick L., Allen, Steven W., Ebeling, Harald, Burchat, Patricia R., Burke, David L., Donovan, David, Morris, R. Glenn, Blandford, Roger, Erben, Thomas, and Mantz, Adam
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Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
This is the first in a series of papers in which we measure accurate weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known at redshifts 0.15
- Published
- 2012
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12. An intercomparison of EarthCARE cloud, aerosol, and precipitation retrieval products.
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Mason, Shannon L., Barker, Howard W., Cole, Jason N. S., Docter, Nicole, Donovan, David P., Hogan, Robin J., Hünerbein, Anja, Kollias, Pavlos, Puigdomènech Treserras, Bernat, Qu, Zhipeng, Wandinger, Ulla, and van Zadelhoff, Gerd-Jan
- Subjects
AEROSOLS ,MULTIPLE scattering (Physics) ,ICE clouds ,BACKSCATTERING ,OPTICAL properties ,TIME series analysis - Abstract
The objective of the Earth Cloud, Aerosol, and Radiation Explorer (EarthCARE) mission is to infer attributes of cloud, aerosol, precipitation, and radiation from observations made by four complementary instruments. This requires the development of single-instrument and multiple-instrument (i.e. synergistic) retrieval algorithms that employ measurements made by one, or more, of EarthCARE's cloud-profiling radar (CPR), atmospheric lidar (ATLID), and multi-spectral imager (MSI); its broadband radiometer (BBR) places the retrieved quantities in the context of the surface–atmosphere radiation budget. To facilitate the development and evaluation of ESA's EarthCARE production model prior to launch, sophisticated instrument simulators were developed to produce realistic synthetic EarthCARE measurements for simulated conditions provided by cloud-resolving models. While acknowledging that the physical and radiative representations of cloud, aerosol, and precipitation in the test scenes are based on numerical models, the opportunity to perform detailed evaluations wherein the "truth" is known provides insights into the performance of EarthCARE's instruments and retrieval algorithms. This level of omniscience will not be available for the evaluation of in-flight EarthCARE retrieval products, even during validation activities coordinated with ground-based and airborne measurements. In this study, we compare EarthCARE retrieval products both statistically across all simulated scenes and from a specific time series from a single scene. For ice clouds, it is shown that retrieved profiles of ice water content and effective particle size made by the ATLID-CPR-MSI cloud, aerosols, and precipitation (ACM-CAP) synergistic algorithm are consistently more accurate than those from its single-instrument counterparts. While liquid clouds are often difficult to detect from satellite-borne sensors, especially for multi-layered clouds, ACM-CAP benefits from combined constraints from lidar backscatter, solar radiances, and radar-path-integrated attenuation but still exhibits non-trivial random error. For precipitation retrievals, the CPR cloud and precipitation product (C-CLD) and ACM-CAP have a similar performance when well-constrained by CPR measurements. The greatest differences are in coverage, with ACM-CAP reporting retrievals in the melting layer, and in heavy precipitation, where CPR signals are dominated by multiple scattering and attenuation. Aerosol retrievals from ATLID compensate for a high degree of measurement noise in a number of ways, with the ATLID extinction, backscatter, and depolarisation (A-EBD) product and ACM-CAP demonstrating similar performance. The multi-spectral imager (MSI) cloud optical properties (M-COP) product performs very well for unambiguous cloud layers. Similarly, the MSI aerosol optical thickness (M-AOT) product performs well when radiances are unaffected by cloud, but both products provide little information about vertical profiles of properties. Finally, a summary of the performance of all retrieval products and their random errors is provided. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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13. Detection of aerosol and cloud features for the EarthCARE atmospheric lidar (ATLID): the ATLID FeatureMask (A-FM) product
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van Zadelhoff, Gerd-Jan, primary, Donovan, David P., additional, and Wang, Ping, additional
- Published
- 2023
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- View/download PDF
14. An intercomparison of EarthCARE cloud, aerosol and precipitation retrieval products
- Author
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Mason, Shannon L., primary, Cole, Jason N. S., additional, Docter, Nicole, additional, Donovan, David P., additional, Hogan, Robin J., additional, Hünerbein, Anja, additional, Kollias, Pavlos, additional, Puigdomènech Treserras, Bernat, additional, Qu, Zhipeng, additional, Wandinger, Ulla, additional, and van Zadelhoff, Gerd-Jan, additional
- Published
- 2023
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15. Probing the Large-Scale Structure Around the Most Distant Galaxy Clusters from the Massive Cluster Survey
- Author
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Kartaltepe, Jeyhan S., Ebeling, Harald, Ma, C. J., and Donovan, David
- Subjects
Astrophysics - Abstract
We present maps of the cosmic large-scale structure around the twelve most distant galaxy clusters from the Massive Cluster Survey (MACS) as traced by the projected surface density of galaxies on the cluster red sequence. Taken with the Suprime-Cam wide-field camera on the Subaru telescope, the images used in this study cover a 27x27 arcmin^2 area around each cluster, corresponding to 10 x 10 Mpc^2 at the median redshift of z = 0.55 of our sample. We directly detect satellite clusters and filaments extending over the full size of our imaging data in the majority of the clusters studied, supporting the picture of mass accretion via infall along filaments suggested by numerical simulations of the growth of clusters and the evolution of large-scale structure. A comparison of the galaxy distribution near the cluster cores with the X-ray surface brightness as observed with Chandra reveals, in several cases, significant offsets between the gas and galaxy distribution, indicative of ongoing merger events. The respective systems are ideally suited for studies of the dynamical properties of gas, galaxies, and dark matter. In addition, the large-scale filaments viewed at high contrast in these MACS clusters are prime targets for the direct detection and study of the warm-hot intergalactic medium (WHIM)., Comment: 10 pages, 3 figures, Accepted for publication in MNRAS
- Published
- 2008
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16. The spatial distribution of galaxies of different spectral types in the massive intermediate-redshift cluster MACSJ0717.5+3745
- Author
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Ma, Cheng-Jiun, Ebeling, Harald, Donovan, David, and Barrett, Elizabeth
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Astrophysics - Abstract
We present the results of a wide-field spectroscopic analysis of the galaxy population of the massive cluster MACSJ0717.5+3745 and the surrounding filamentary structure (z=0.55), as part of our systematic study of the 12 most distant clusters in the MACS sample. Of 1368 galaxies spectroscopically observed in this field, 563 are identified as cluster members; of those, 203 are classified as emission-line galaxies, 260 as absorption-line galaxies, and 17 as E+A galaxies (defined by $\frac{H_{\delta}+H_{\gamma}}{2}>6$\AA and no detection of [OII] and $H_{\beta}$ in emission). The variation of the fraction of emission- and absorption-line galaxies as a function of local projected galaxy density confirms the well-known morphology-density relation, and becomes flat at projected galaxy densities less than $\sim 20Mpc^{-2}. Interestingly, 16 out of 17 E+A galaxies lie (in projection) within the ram-pressure stripping radius around the cluster core, which we take to be direct evidence of ram-pressure stripping being the primary mechanism that terminates star-formation in the E+A population of galaxy clusters. This conclusion is supported by the rarity of E+A galaxies in the filament which rules out galaxy mergers as the dominant driver of evolution for E+A galaxies in clusters. In addition, we find the 42 e(a) and 27 e(b) member galaxies, i.e., the dusty-starburst and starburst galaxies respectively, to be spread out across almost the entire study area. Their spatial distribution, which shows a strong preference for the filament region, suggests that starbursts are triggered in relatively low-density environments as galaxies are accreted from the field population., Comment: 16 pages, 15 figures, accepted by ApJ
- Published
- 2008
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17. Optimized production of a biologically active Clostridium perfringens glycosyl hydrolase phage endolysin PlyCP41 in plants using virus-based systemic expression
- Author
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Hammond, Rosemarie W., Swift, Steven M., Foster-Frey, Juli A., Kovalskaya, Natalia Y., and Donovan, David M.
- Published
- 2019
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18. Detection of aerosol and cloud features for the EarthCARE lidar ATLID: the A-FM product
- Author
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van Zadelhoff, Gerd-Jan, primary, Donovan, David P., additional, and Wang, Ping, additional
- Published
- 2023
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- View/download PDF
19. An intercomparison of EarthCARE cloud, aerosol and precipitation retrieval products.
- Author
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Mason, Shannon L., Cole, Jason N. S., Docter, Nicole, Donovan, David P., Hogan, Robin J., Hünerbein, Anja, Kollias, Pavlos, Treserras, Bernat Puigdomènech, Qu, Zhipeng, Wandinger, Ulla, and Zadelhoff, Gerd-Jan van
- Subjects
ICE clouds ,AEROSOLS ,MULTIPLE scattering (Physics) ,ATMOSPHERIC radiation ,BACKSCATTERING ,OPTICAL properties - Abstract
The mission of the Earth cloud, aerosol and radiation explorer (EarthCARE) mission to observe cloud, aerosol, precipitation and radiation using four complementary instruments requires the development of many single-instrument and synergistic algorithms for the retrieval of geophysical quantities. The retrieval products employ one or more of the cloud profiling radar (CPR), atmospheric lidar (ATLID) and multispectral imager (MSI), while the broadband radiometer (BBR) places the retrieved quantities in the context of the atmospheric radiation budget. To facilitate the development and evaluation of the ESA EarthCARE production model prior to launch, sophisticated instrument simulators have been developed to produce realistic synthetic EarthCARE measurements from the output of cloud-resolving model simulations. While acknowledging that the physical and radiative representation of cloud, aerosol and precipitation in the test scenes are based on numerical models, the opportunity to perform a detailed evaluation wherein the model ''truth'' is known has provided rare insights into the performance of EarthCARE's instruments and retrieval algorithms. This level of omniscience will not be available for the evaluation of in-flight EarthCARE retrieval products, even during validation activities coordinated with ground-based and airborne measurements. In this study we intercompare EarthCARE retrieval products from within the ESA production model both statistically across all simulated EarthCARE granules, and using timeseries of data from an individual scene. The comparison between the retrieved quantities helps to illustrate the strengths and limitations of the single-instrument retrievals, and the degrees to which the synergistic retrieval and composite products can represent the entire atmosphere of clouds, aerosols and precipitation. We show that radar-lidar synergy has the greatest impact in ice clouds; when compared with single-instrument radar and lidar retrievals, the synergistic ATLID-CPR-MSI cloud, aerosols, and precipitation (ACM-CAP) product accurately retrieves profiles of both ice water content and effective radius. While liquid cloud is difficult to detect directly from spaceborne remote sensors, especially in complex and layered scenes, the synergistic retrieval benefits from combined constraints from lidar backscatter, solar radiances and radar path-integrated attenuation, but still exhibits a high degree of random error. For precipitation retrievals, the CPR cloud and precipitation product (C-CLD) and ACM-CAP have similar performance when well-constrained by CPR measurements. The greatest differences are in coverage, with ACM-CAP reporting retrievals in the melting layer, and in heavy precipitation where the radar is dominated by multiple scattering and attenuation). Aerosol retrievals from ATLID compensate for a high degree of measurement noise in a number of ways, with the ATLID extinction, backscatter and depolarization (A-EBD) product and ACM-CAP demonstrating similar performance in the test scenes. The multispectral imager (MSI) cloud optical properties (M-COP) product performs very well in unambiguous cloud layers; similarly, the MSI aerosol optical thickness (M-AOT) product performs well where the possibility of contamination by cloud signal is very low. A summary of the performance of all retrieval products is provided, and may help to inform the selection of EarthCARE data products by future users. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. Supplementary material to "Numerical Model Generation of Test Frames for Pre-launch Studies of EarthCARE’s Retrieval Algorithms and Data Management System"
- Author
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Qu, Zhipeng, primary, Donovan, David P., additional, Barker, Howard W., additional, Cole, Jason N. S., additional, Shephard, Mark W., additional, and Huijnen, Vincent, additional
- Published
- 2022
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21. Numerical Model Generation of Test Frames for Pre-launch Studies of EarthCARE’s Retrieval Algorithms and Data Management System
- Author
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Qu, Zhipeng, primary, Donovan, David P., additional, Barker, Howard W., additional, Cole, Jason N. S., additional, Shephard, Mark W., additional, and Huijnen, Vincent, additional
- Published
- 2022
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22. Supplementary material to "The classification of atmospheric hydrometeors and aerosols from the EarthCARE radar and lidar: the A-TC, C-TC and AC-TC products"
- Author
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Irbah, Abdanour, primary, Delanoë, Julien, additional, van Zadelhoff, Gerd-Jan, additional, Donovan, David P., additional, Kollias, Pavlos, additional, Puigdomènech Treserras, Bernat, additional, Mason, Shannon, additional, Hogan, Robin J., additional, and Tatarevic, Aleksandra, additional
- Published
- 2022
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23. The classification of atmospheric hydrometeors and aerosols from the EarthCARE radar and lidar: the A-TC, C-TC and AC-TC products
- Author
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Irbah, Abdanour, primary, Delanoë, Julien, additional, van Zadelhoff, Gerd-Jan, additional, Donovan, David P., additional, Kollias, Pavlos, additional, Puigdomènech Treserras, Bernat, additional, Mason, Shannon, additional, Hogan, Robin J., additional, and Tatarevic, Aleksandra, additional
- Published
- 2022
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24. A Chimeric LysK-Lysostaphin Fusion Enzyme Lysing Staphylococcus aureus Cells: a Study of Both Kinetics of Inactivation and Specifics of Interaction with Anionic Polymers
- Author
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Filatova, Lyubov Y., Donovan, David M., Ishnazarova, Nadiya T., Foster-Frey, Juli A., Becker, Stephen C., Pugachev, Vladimir G., Balabushevich, Nadezda G., Dmitrieva, Natalia F., and Klyachko, Natalia L.
- Published
- 2016
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25. The classification of atmospheric hydrometeors and aerosols from the EarthCARE radar and lidar: the A-TC, C-TC and AC-TC products.
- Author
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Irbah, Abdanour, Delanoë, Julien, van Zadelhoff, Gerd-Jan, Donovan, David P., Kollias, Pavlos, Puigdomènech Treserras, Bernat, Mason, Shannon, Hogan, Robin J., and Tatarevic, Aleksandra
- Subjects
ATMOSPHERIC aerosols ,ICE clouds ,LIDAR ,MULTIPLE scattering (Physics) ,RADAR ,ATMOSPHERE ,PRECIPITATION scavenging - Abstract
The EarthCARE mission aims to probe the Earth's atmosphere by measuring cloud and aerosol profiles using its active instruments, the Cloud Profiling Radar (CPR) and ATmospheric LIDar (ATLID). The correct identification of hydrometeors and aerosols from atmospheric profiles is an important step in retrieving the properties of clouds, aerosols and precipitation. Ambiguities in the nature of atmospheric targets can be removed using the synergy of collocated radar and lidar measurements, which is based on the complementary spectral response of radar and lidar relative to atmospheric targets present in the profiles. The instruments are sensitive to different parts of the particle size distribution and provide independent but overlapping information in optical and microwave wavelengths. ATLID is sensitive to aerosols and small cloud particles, and CPR is sensitive to large ice particles, snowflakes and raindrops. It is therefore possible to better classify atmospheric targets when collocated radar and lidar measurements exist compared to using a single instrument. The cloud phase, precipitation and aerosol type within the column sampled by the two instruments can then be identified. ATLID-CPR target classification (AC-TC) is the product created for this purpose by combining the ATLID target classification (A-TC) and CPR target classification (C-TC). AC-TC is crucial for the subsequent synergistic retrieval of cloud, aerosol and precipitation properties. AC-TC builds upon previous target classifications using CloudSat and CALIPSO synergy while providing richer target classification using the enhanced capabilities of EarthCARE's instruments, specifically CPR's Doppler velocity measurements to distinguish snow and rimed snow from ice clouds and ATLID's lidar ratio measurements to objectively discriminate between different aerosol species and optically thin ice clouds. In this paper, we first describe how the single-instrument A-TC and C-TC products are derived from ATLID and CPR measurements. Then the AC-TC product, which combines the A-TC and C-TC classifications using a synergistic decision matrix, is presented. Simulated EarthCARE observations based on combined cloud-resolving and aerosol model data are used to test the processors generating the target classifications. Finally, the target classifications are evaluated by quantifying the fractions of ice and snow, liquid clouds, rain, and aerosols in the atmosphere that can be successfully identified by each instrument and their synergy. We show that radar–lidar synergy helps better detect ice and snow, with ATLID detecting radiatively important optically thin cirrus and cloud tops, while CPR penetrates most deep and highly concentrated ice clouds. The detection of rain and drizzle is entirely due to C-TC, while that of liquid clouds and aerosols is due to A-TC. The evaluation also shows that simple assumptions can be made to compensate for when the instruments are obscured by extinction (ATLID) or surface clutter and multiple scattering (CPR); this allows for the recovery of the majority of liquid cloud not detected by the active instruments. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
26. Aerosol first indirect effect of African smoke at the cloud base of marine cumulus clouds over Ascension Island, southern Atlantic Ocean.
- Author
-
de Graaf, Martin, Sarna, Karolina, Brown, Jessica, Tenner, Elma V., Schenkels, Manon, and Donovan, David P.
- Subjects
CLOUD droplets ,AEROSOLS ,OCEAN ,ISLANDS ,LIDAR ,CUMULUS clouds ,ICE clouds - Abstract
The interactions between aerosols and clouds are among the least understood climatic processes and were studied over Ascension Island. A ground-based UV polarization lidar was deployed on Ascension Island, which is located in the stratocumulus-to-cumulus transition zone of the southeastern Atlantic Ocean, to infer cloud droplet sizes and droplet number density near the cloud base of marine boundary layer cumulus clouds. The aerosol–cloud interaction (ACI) due to the presence of smoke from the African continent was determined during the monsoonal dry season. In September 2016, a cloud droplet number density ACI N of 0.3 ± 0.21 and a cloud effective radius ACI r of 0.18 ± 0.06 were found, due to the presence of smoke in and under the clouds. Smaller droplets near the cloud base makes them more susceptible to evaporation, and smoke in the marine boundary layer over the southeastern Atlantic Ocean will likely accelerate the stratocumulus-to-cumulus transition. The lidar retrievals were tested against more traditional radar–radiometer measurements and shown to be robust and at least as accurate as the lidar–radiometer measurements. The lidar estimates of the cloud effective radius are consistent with previous studies of cloud base droplet sizes. The lidar has the large advantage of retrieving both cloud and aerosol properties using a single instrument. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Synergistic streptococcal phage λSA2 and B30 endolysins kill streptococci in cow milk and in a mouse model of mastitis
- Author
-
Schmelcher, Mathias, Powell, Anne M., Camp, Mary J., Pohl, Calvin S., and Donovan, David M.
- Published
- 2015
- Full Text
- View/download PDF
28. DARCLOS: a cloud shadow detection algorithm for TROPOMI
- Author
-
Trees, Victor J. H., primary, Wang, Ping, additional, Stammes, Piet, additional, Tilstra, Lieuwe G., additional, Donovan, David P., additional, and Siebesma, A. Pier, additional
- Published
- 2022
- Full Text
- View/download PDF
29. Detection of aerosol and cloud features for the EarthCARE lidar ATLID: the A-FM product.
- Author
-
van Zadelhoff, Gerd-Jan, Donovan, David P., and Ping Wang
- Subjects
- *
LIDAR , *BACKSCATTERING , *AEROSOLS , *ICE clouds - Abstract
The EarthCARE satellite mission's objective is to retrieve profiles of the aerosol and water cloud physical properties using the combination of cloud-profiling radar (CPR), high spectral resolution UV lidar (ATLID), and passive multi-spectral spectral imager (MSI) data. Based on synergistic retrievals using data from these instruments, the 3D atmospheric cloud/aerosol state is estimated, which then are used to forward modelled radiative properties, which may then be compared to co-incident broad band radiometer (BBR) measurements. A high spectral resolution lidar enables the independent retrieval of extinction and backscatter but, being space-based, suffers from relatively high signal-to-noise levels. The ATLID FeatureMask (A-FM) product provides a probability mask for the existence of atmospheric features within the lidar profiles. Next to this, it also identifies those regions where the lidar beam has been fully attenuated and when the surface has impacted the measured lidar backscatter signals. From the pixels assigned as clear sky with no features present above, the clear sky averaged profiles for the three ATLID channels, the co-polar Mie channel, the total cross channel and the co-polar Rayleigh channel, are created. These 'feature-free' or 'clear-sky' profiles are useful for e.g. the quality of the ATLID l1 attenuated backscatters. The scientific goals of the A-FM product is to guide smoothing strategies within the ATLID profile retrieval algorithm which is one step further in the EarthCARE L2 processing chain. As a secondary product a frame-by-frame evaluation of the ATLID L1b cross talk calibration can be preformed by comparing the retrieved clear sky profiles to the expected channel profiles. The A-FM algorithm has been evaluated thoroughly using the synthetic test scenes. The A-FM product has been applied to both synthetic data from the EarthCARE end-to-end simulator (ECSIM) ass well as ALADIN L1 data from the Aeolus wind-lidar mission. Comparisons against the ECSIM model truth indicate A-FM has a percentage correctness >0.9 and is capable of reliably detecting aerosol and cloud regions with extinctions > 1E-5 m-1. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
30. Radiative Flux Estimation from a Broadband Radiometer Using Synthetic Angular Models in the EarthCARE Mission Framework. Part II : Evaluation
- Author
-
Domenech, Carlos, Lopez-Baeza, Ernesto, Donovan, David P., and Wehr, Tobias
- Published
- 2012
31. Radiative Flux Estimation from a Broadband Radiometer Using Synthetic Angular Models in the EarthCARE Mission Framework. Part I : Methodology
- Author
-
Domenech, Carlos, Lopez-Baeza, Ernesto, Donovan, David P., and Wehr, Tobias
- Published
- 2011
32. Using Continuous Ground-Based Radar and Lidar Measurements for Evaluating the Representation of Clouds in Four Operational Models
- Author
-
Bouniol, Dominique, Protat, Alain, Delanoë, Julien, Pelon, Jacques, Piriou, Jean-Marcel, Bouyssel, François, Tompkins, Adrian M., Wilson, Damian R., Morille, Yohann, Haeffelin, Martial, O’Connor, Ewan J., Hogan, Robin J., Illingworth, Anthony J., Donovan, David P., and Baltink, Henk-Klein
- Published
- 2010
33. TWOMEY EFFECT IN SUBTROPICAL STRATOCUMULUS CLOUDS FROM UV DEPOLARIZATION LIDAR
- Author
-
de Graaf Martin, Brown Jessica, and Donovan David
- Subjects
Physics ,QC1-999 - Abstract
Marine stratocumulus clouds are important climate regulators, reflecting sunlight over a dark ocean background. A UV-depolarization lidar on Ascension, a small remote island in the south Atlantic, measured cloud droplet sizes and number concentration using an inversion method based on Monte Carlo (MC) modelling of multiple scattering in idealised semiadiabatic clouds. The droplet size and number concentration weremodulated due to smoke from the African continent, measured by the same instrument.
- Published
- 2018
- Full Text
- View/download PDF
34. Earthcare atlid extinction and backscatter retrieval algorithms
- Author
-
Donovan David, Zadelhoff Gerd-Jan van, Daou David, and Wandinger Ulla
- Subjects
Physics ,QC1-999 - Abstract
ATLID stands for “ATmospheric LIDar” and is the lidar to be flown on the Earth Clouds and Radiation Explorer (EarthCARE) platform in early 2019. ATLID is a High-Spectral Resolution (HSRL) system operating at 355nm. This presentation will introduce the ATLID level-2 retrieval algorithms being implemented in order to derive cloud and aerosol optical properties
- Published
- 2018
- Full Text
- View/download PDF
35. EarthCARE Aerosol and Cloud Layer and Column Products
- Author
-
Wandinger Ulla, Hünerbein Anja, Horn Stefan, Schneider Florian, Donovan David, van Zadelhoff Gerd-Jan, Daou David, Docter Nicole, Fischer Jürgen, and Filipitsch Florian
- Subjects
Physics ,QC1-999 - Abstract
We introduce the development of EarthCARE Level 2 layer products derived from profile measurements of the high-spectral-resolution lidar ATLID and column products obtained from combined information of ATLID and the Multi-Spectral Imager (MSI). Layer products include cloud top height as well as aerosol layer boundaries and mean optical properties along the satellite nadir track. Synergistic column products comprise cloud top height, Ångström exponent, and aerosol type both along-track and across the MSI swath.
- Published
- 2018
- Full Text
- View/download PDF
36. Comparison between two lidar methods to retrieve microphysical properties of liquid-water clouds
- Author
-
Jimenez Cristofer, Ansmann Albert, Donovan David, Engelmann Ronny, Schmidt Jörg, and Wandinger Ulla
- Subjects
Physics ,QC1-999 - Abstract
Since 2010, the Raman dual-FOV lidar system permits the retrieval of microphysical properties of liquid-water clouds during nighttime. A new robust lidar depolarization approach was recently introduced, which permits the retrieval of these properties as well, with high temporal resolution and during daytime. To implement this approach, the lidar system was upgraded, by adding a three channel depolarization receiver. The first preliminary retrieval results and a comparison between both methods is presented.
- Published
- 2018
- Full Text
- View/download PDF
37. Testing IWC Retrieval Methods Using Radar and Ancillary Measurements with In Situ Data
- Author
-
Heymsfield, Andrew J., Protat, Alain, Austin, Richard T., Bouniol, Dominique, Hogan, Robin J., Delanoë, Julien, Okamoto, Hajime, Sato, Kaori, van Zadelhoff, Gerd-Jan, Donovan, David P., and Wang, Zhien
- Published
- 2008
38. Achievement Based Funding: The Michigan Experience with Compensatory Education.
- Author
-
Rumbaugh, Stanley A. and Donovan, David L.
- Abstract
Prior to 1971, a local district's eligibility to participate in Michigan's Compensatory Education Program was established on the basis of socioeconomic deprivation of the student body, the state legislature mandated the kind of expenditures that were allowable, and school district eligibility was determined annually. In 1971, the state board of education proposed a new three-year experimental program with the following elements: a direct measure of basic skills in reading and mathematics as the measure of eligibility, assurance of three-year funding, provision of funding adjustments to be determined by program success, provision for an annual evaluation of each pupil's progress to determine his level of attainment, extension of program discretion to the local school district, and provision for district funding as a means of providing flexibility to serve all pupils. Although the district accountability was never fully operational, it has been determined that school districts can be held accountable for educating the lowest achieving pupils and that additional money for educational programs in basic skills can result in higher attainment. Regardless of the conceptual framework of future programs, Michigan is likely to continue to use actual student achievement as the indicator of need and success. (Author/IRT)
- Published
- 1976
39. State Assessment: A Beginning Toward School Improvement.
- Author
-
Michigan State Dept. of Education, Lansing. and Donovan, David L.
- Abstract
The educational assessment of basic skills in Michigan has grown from a needed source of information on achievement to an integral part of statewide efforts to improve school achievement. The educational assessment program first provided information to address two important educational questions: "What is the level of basic skills achievement in Michigan?" and "Which children, schools and school districts are successful and which are in need of assistance?" A third question, "What makes some schools more successful than others?" was then raised. This more complex question goes far beyond assessment practices and has served as the basis for extensive studies and reviews of the literature. A synthesis of the findings resulted in the identification of eight principles, or "Variables that Make a Difference." The "alterable variables" school staff may employ at the school level to improve instruction and achievement, are identified as: time on instruction, parental involvement, role of the principal, teacher expectations, classroom structure, pupil reinforcement, tutoring and classroom recitation. (Author)
- Published
- 1980
40. DARCLOS: a cloud shadow detection algorithm for TROPOMI
- Author
-
Trees, Victor, primary, Wang, Ping, additional, Stammes, Piet, additional, Tilstra, Lieuwe G., additional, Donovan, David P., additional, and Siebesma, A. Pier, additional
- Published
- 2021
- Full Text
- View/download PDF
41. Objectives and Procedures: The First Report of the 1972-73 Michigan Educational Assessment Program.
- Author
-
Michigan State Dept. of Education, Lansing. and Donovan, David
- Abstract
The objectives of the Michigan Educational Assessment Program for 1972-73 are: (1) to provide State officials and citizens with information which contributes to an understanding of the educational needs of the State's school children and to the analysis of the educational system's response to these needs; (2) to provide citizens and educators with information regarding the public school districts and schools, the children's needs, and the district's responses to these needs; (3) to provide school districts with basic information regarding students to help students, parents, and educators assess their progress; and (4) to provide citizens with information regarding the progress of the Michigan educational system as a whole and the progress of its school districts and schools over a period of years. The methodology to be used in accomplishing these objectives is an educational management system, known as the accountability model, which has six basic components: (1) identification of common goals, (2) establishment of performance objectives, (3) assessment of needs, (4) analysis of delivery systems, (5) evaluation, and (6) recommendation for improvement. Procedural issues concern: who will conduct the program, who will be included in the program, which fourth and seventh graders will be given the assessment battery, how long it will take to administer the battery (word relationships, reading, mechanics of written English, mathematics, and composite achievement), steps being taken to assure some degree of standardization in administeration, who will administer the battery, when it will be administered, etc. (DB)
- Published
- 1972
42. Levels of Educational Performance and Related Factors in Michigan. The Fifth Report of the 1970-71 Michigan Educational Assessment Program.
- Author
-
Michigan State Dept. of Education, Lansing. Research, Evaluation, and Assessment Services. and Donovan, David
- Abstract
The fifth report of the Michigan Educational Assessment Program contains education profiles for State school districts, schools and pupils. The profiles deal with: (1) human resources--such as pupil/teacher ratio and percent of teachers with master's degree; (2) school financial resources--such as local revenue per pupil and State school aid per pupil; (3) student background; (4) school/student performance (grades 4 and 7)--attitude measures, basic skills measures, and dropout rate; and (5) school or district size. The profiles present information assembled separately for each of five community types--metropolitan core city, city, urban fringe, town, and rural. Within this framework, profiles are constructed from: (1) district-level mean scores on the educational assessment measures; (2) school-level mean scores; and (3) individual pupil scores. Precautions that should be observed and definitions of statistical terms are included. Appendix A contains definitions of the five community types; the measures used in the educational assessment program are defined in Appendix B. (For related documents, see TM 002 326, 328-330.) (KM)
- Published
- 1972
43. Distribution of Educational Performance and Related Factors in Michigan. The Sixth Report of the 1970-71 Michigan Educational Assessment Program.
- Author
-
Michigan State Dept. of Education, Lansing. Research, Evaluation, and Assessment Services. and Donovan, David
- Abstract
The sixth report of the Michigan Educational Assessment Program contains eight educational distribution profiles. Schools and districts were classified into upper, middle, and lower thirds on the basis of the average scores (in grades 4 and 7) in composite achievement and socioeconomic status, and their scores on all assessment measures were charted. The assessment measures were: (1) human resources--such as pupil/teacher ratio and percent of teachers with master's degree; (2) school financial resources--such as local revenue per pupil and State school aid per pupil; (3) student background; (4) school/student performance--attitude measures, basic skills measures, and dropout rate; and (5) school or district size. The purpose of this report was to find whether schools or districts that rank high, in the middle, or low on composite achievement or socioeconomic status have a similar rank on other assessment measures. It was found that this is generally true, but certain exceptions and limitations on interpretation are specified. An appendix contains definitions of the educational assessment measures. (For related documents, see TM 002 326-327, 329-330.)
- Published
- 1972
44. Numerical Model Generation of Test Frames for Pre-launch Studies of EarthCARE's Retrieval Algorithms and Data Management System.
- Author
-
Zhipeng Qu, Donovan, David P., Barker, Howard W., Cole, Jason N. S., Shephard, Mark W., and Huijnen, Vincent
- Subjects
- *
DATA management , *MESOSCALE convective complexes , *INFORMATION retrieval , *ATMOSPHERIC layers , *RADIATIVE transfer - Abstract
The Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) satellite consists of active and passive sensors whose observations will be acted on by an array of retrieval algorithms. EarthCARE's retrieval algorithms have undergone pre-launch verifications within a virtual observing system that consists of 3D atmosphere-surface data produced by the Global Environmental Multi-scale (GEM) NWP model, and instrument simulators that when applied to NWP data yield synthetic observations for EarthCARE's four sensors. Retrieval algorithms operate on the synthetic observations and their estimates go into radiative transfer models that produce top-of-atmosphere solar and thermal broadband radiative quantities, which are compared to synthetic broadband measurements thus mimicking EarthCARE's radiative closure assessment. Three high-resolution test frames were simulated; each measures ~6,200 km along-track by 200 km across-track. Horizontal grid-spacing is 250 m and there are 57 atmospheric layers up to 10 mb. The frames span wide ranges of conditions and extend over: i) Greenland to The Caribbean crossing a cold front off Nova Scotia; ii) Nunavut to Baja California crossing over Colorado's Rooky Mountains; and iii) central equatorial Pacific Ocean that includes a mesoscale convective system. This report discusses how the test frames were produced and presents their key geophysical features. All data are publicly available and, owing to their highresolution, could be used to simulate observations for other measurement systems. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
45. The classification of atmospheric hydrometeors and aerosols from the EarthCARE radar and lidar: the A-TC, C-TC and AC-TC products.
- Author
-
Irbah, Abdanour, Delanoë, Julien, Zadelhoff, Gerd-Jan van, Donovan, David P., Kollias, Pavlos, Treserras, Bernat Puigdomènech, Mason, Shannon, Hogan, Robin J., and Tatarevic, Aleksandra
- Subjects
ATMOSPHERIC aerosols ,CLOUD computing ,METEOROLOGICAL precipitation ,PARTICLE size distribution ,WAVELENGTHS - Abstract
The EarthCARE mission aims to probe the Earth's atmosphere by measuring cloud and aerosol profiles using its active instruments, the Cloud Profiling Radar (CPR) and Atmospheric Lidar (ATLID). The correct identification of hydrometeors and aerosols from atmospheric profiles is an important step in retrieving the properties of clouds, aerosols and precipitation. Ambiguities in the nature of atmospheric targets can be removed using the synergy of collocated radar and lidar measurements, which is based on the complementary spectral response of radar and lidar relative to atmospheric targets present in the profiles. The instruments are sensitive to different parts of the particle size distribution, and provide independent but overlapping information in optical and microwave wavelengths. ATLID is sensitive to aerosols and small cloud particles and CPR to large ice particles, snowflakes and raindrops. It is therefore possible to better classify atmospheric targets when collocated radar and lidar measurements exist compared to a single instrument. The cloud phase, precipitation and aerosol type within the column sampled by the two instruments can then be identified. ATLID-CPR Target Classification (AC-TC) is the product created for this purpose by combining the ATLID Target Classification (A-TC) and CPR Target Classification (C-TC). AC-TC is crucial for the subsequent synergistic retrieval of cloud, aerosol and precipitation properties. AC-TC builds upon previous target classifications using CloudSat/CALIPSO synergy, while providing richer target classification using the enhanced capabilities of EarthCARE's instruments: CPR's Doppler velocity measurements to distinguish snow and rimed snow from ice clouds, and ATLID's lidar ratio measurements to objectively discrimination between different aerosol species and optically thin ice clouds. In this paper we first describe how the single-instrument A-TC and C-TC products are derived from ATLID and CPR measurements. Then the AC-TC product, which combines the A-TC and C-TC classifications using a synergistic decision matrix, is presented. Simulated EarthCARE observations are used to test the processors generating the target classifications, with results presented using the Halifax scene. Finally, the target classifications are evaluated by quantifying the fractions of ice and snow, liquid clouds, rain and aerosols in the atmosphere that can be successfully identified by each instrument and their synergy. We show that radar-lidar synergy helps better detect ice and snow, with ATLID detecting radiatively-important optically thin cirrus and cloud-tops while CPR penetrates most deep and highly concentrated ice clouds. The detection of rain and drizzle is entirely due to C-TC, while that of liquid clouds and aerosols is due to A-TC. The evaluation also shows that simple assumptions can be made to compensate for when the instruments are obscured by extinction (ATLID) or surface clutter and multiple scattering (CPR); this allows for the recovery of a majority of liquid cloud not detected by the active instruments. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. Estimating the optical extinction of liquid water clouds in the cloud base region
- Author
-
Sarna, Karolina, primary, Donovan, David P., additional, and Russchenberg, Herman W. J., additional
- Published
- 2021
- Full Text
- View/download PDF
47. Aerosol first indirect effect of African smoke in marine stratocumulus clouds over Ascension Island, south Atlantic Ocean.
- Author
-
de Graaf, Martin, Sarna, Karolina, Brown, Jessica, Tenner, Elma, Schenkels, Manon, and Donovan, David P.
- Abstract
The first indirect or Twomey effect was measured in marine stratocumulus clouds over the south Atlantic Ocean. Measurements were collected over Ascension Island, a remote spot between the African and South American continents. This area is known for its persistent broken cloud cover and smoke intrusions from vegetation fires in Africa during the monsoonal dry period. The interactions between aerosols and clouds are among the least understood climatic processes and were studied over Ascension using a combination of in-situ and remote sensing instruments. Particularly, a new method using a groundbased UV-polarisation lidar to infer cloud droplet sizes and droplet number concentrations was tested against more traditional radar-radiometer measurements. The lidar measurements show to be robust and at least as accurate as the lidar-radiometer measurements and have the large advantage of depending on a single instrument. The UV-lidar was deployed on Ascension for one month in the summer of 2016 and one month in the summer of 2017. In 2016, the presence of smoke in the troposphere decreased the effective cloud droplet size and increased the average droplet number distribution. In 2017, alignment problems of the lidar prohibited conclusions about a Twomey effect. The cloud microphysical properties showed differences between the two years depending on the meteorological circumstances. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
48. Staphylococcal Phage 2638A endolysin is lytic for Staphylococcus aureus and harbors an inter-lytic-domain secondary translational start site
- Author
-
Abaev, Igor, Foster-Frey, Juli, Korobova, Olga, Shishkova, Nina, Kiseleva, Natalia, Kopylov, Pavel, Pryamchuk, Sergey, Schmelcher, Mathias, Becker, Stephen C., and Donovan, David M.
- Published
- 2013
- Full Text
- View/download PDF
49. Comparison of 2D video and electrogoniometry measurements of knee flexion angle during a countermovement jump and landing task
- Author
-
Petushek, Erich, Richter, Chris, Donovan, David, Ebben, William P., Watts, Phillip B., and Jensen, Randall L.
- Published
- 2012
- Full Text
- View/download PDF
50. Demonstration of Neutral Pressure Sensitivity in an Interferometric Fiber Optic Temperature Sensor
- Author
-
Lee, Seungsup, Donovan, David, Han, Ming, Reinke, Matthew, Shafer, Morgan, Sheng, Qiwen, and Uddin, Nezam
- Abstract
An interferometric fiber optic temperature sensor (FOTS) was demonstrated to have neutral pressure sensitivity in various vacuum regimes. The sensor was based on a fiber optic Fabry–Perot interferometer that showed negligible susceptibility to electromagnetic interference (EMI) in a fusion environment. The compact design (
$600~\mu \text{m}$ $154~\mu \text{m}$ - Published
- 2022
- Full Text
- View/download PDF
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