1,566 research outputs found

    LADAR Performance Simulations with a High Spectral Resolution Atmospheric Transmittance and Radiance Model- LEEDR

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    In this study of atmospheric effects on Geiger Mode laser ranging and detection (LADAR), the parameter space is explored primarily using the Air Force Institute of Technology Center for Directed Energy\u27s (AFIT/CDE) Laser Environmental Effects Definition and Reference (LEEDR) code. The LADAR system is assessed at operationally representative wavelengths of 1.064, 1.56 and 2.039 μm with several up and down looking engagement geometries at locations worldwide. Results computed with LEEDR are compared to standard atmosphere and Fast Atmospheric Signature Code (FASCODE) assessments. Results show significant climate dependence, but large variances between climatological and standard atmosphere assessments. An overall average absolute mean difference ratio of 1.03 is found when climatological signal to noise ratios at forty locations are compared to their equivalent standard atmosphere assessment. Atmospheric transmission is shown to not always correlate with signal to noise ratios between different atmosphere profiles. Allowing aerosols to swell with relative humidity proves to be significant especially for up looking geometries reducing the signal to noise ratio several orders of magnitude. Turbulence blurring shows that the up looking LADAR system has little capability at a 50km range yet has little impact at a 3km range

    Deciduous Broadleaf Bidirectional Scattering Distribution Function (BSDF): Measurements, Modeling, and Impacts on Waveform Lidar Forest Assessments

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    Lidar (light detection and ranging) remote sensing has proven high accuracy/precision for quantification of forest biophysical parameters, many of which are needed for operational and ecological management. Although the significant effect of Bidirectional Scattering Distribution Functions (BSDF) on remote sensing of vegetation is well known, current radiative transfer simulations, designed for the development of remote sensing systems for ecological observation, seldom take leaf BSDF into account. Moreover, leaf directional scattering measurements are almost nonexistent, particularly for transmission. Previous studies have been limited in their electromagnetic spectrum extent, lacked validated models to capture all angles beyond measurements, and did not adequately incorporate transmission scattering. Many current remote sensing simulations assume leaves with Lambertian reflectance, opaque leaves, or apply purely Lambertian transmission, even though the validity of these assumptions and the effect on simulation results are currently unknown. This study captured deciduous broadleaf BSDFs (Norway Maple (Acer platanoides), American Sweetgum (Liquidambar styraciflua), and Northern Red Oak (Quercus rubra)) from the ultraviolet through shortwave infrared spectral regions (350-2500 nm), and accurately modeled the BSDF for extension to any illumination angle, viewing zenith, or azimuthal angle. Relative leaf physical parameters were extracted from the microfacet models delineating the three species. Leaf directional scattering effects on waveform lidar (wlidar) signals and their dependence on wavelength, lidar footprint, view angle, and leaf angle distribution (LAD) were explored using the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model. The greatest effects, compared to Lambertian assumptions, were observed at visible wavelengths, small wlidar footprints, and oblique interrogation angles relative to the mean leaf angle. These effects were attributed to (i) a large specular component of the BSDF in the visible region, (ii) small footprints having fewer leaf angles to integrate over, and (iii) oblique angles causing diminished backscatter due to forward scattering. Opaque leaf assumptions were seen to have the greatest error for near-infrared (NIR) wavelengths with large footprints, due to the increased multi-scatter contribution at these configurations. Armed with the knowledge from this study, researchers are able to select appropriate sensor configurations to account for or limit BSDF effects in forest lidar data

    Land-use change reduces habitat suitability for supporting managed honey bee colonies in the Northern Great Plains

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    Human reliance on insect pollination services continues to increase even as pollinator populations exhibit global declines. Increased commodity crop prices and federal subsidies for biofuel crops, such as corn and soybeans, have contributed to rapid land-use change in the US Northern Great Plains (NGP), changes that may jeopardize habitat for honey bees in a part of the country that supports \u3e40% of the US colony stock. We investigated changes in biofuel crop production and grassland land covers surrounding ~18,000 registered commercial apiaries in North and South Dakota from 2006 to 2014. We then developed habitat selection models to identify remotely sensed land-cover and land-use features that influence apiary site selection by Dakota beekeepers. Our study demonstrates a continual increase in biofuel crops, totaling 1.2 Mha, around registered apiary locations in North and South Dakota. Such crops were avoided by commercial beekeepers when selecting apiary sites in this region. Furthermore, our analysis reveals how grasslands that beekeepers target when selecting commercial apiary locations are becoming less common in eastern North and South Dakota, changes that may have lasting impact on pollinator conservation efforts. Our study highlights how land-use change in the NGP is altering the landscape in ways that are seemingly less conducive to beekeeping. Our models can be used to guide future conservation efforts highlighted in the US national pollinator health strategy by identifying areas that support high densities of commercial apiaries and that have exhibited significant land-use changes

    Land-use change reduces habitat suitability for supporting managed honey bee colonies in the Northern Great Plains

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    Human reliance on insect pollination services continues to increase even as pollinator populations exhibit global declines. Increased commodity crop prices and federal subsidies for biofuel crops, such as corn and soybeans, have contributed to rapid land-use change in the US Northern Great Plains (NGP), changes that may jeopardize habitat for honey bees in a part of the country that supports \u3e40% of the US colony stock. We investigated changes in biofuel crop production and grassland land covers surrounding ~18,000 registered commercial apiaries in North and South Dakota from 2006 to 2014. We then developed habitat selection models to identify remotely sensed land-cover and land-use features that influence apiary site selection by Dakota beekeepers. Our study demonstrates a continual increase in biofuel crops, totaling 1.2 Mha, around registered apiary locations in North and South Dakota. Such crops were avoided by commercial beekeepers when selecting apiary sites in this region. Furthermore, our analysis reveals how grasslands that beekeepers target when selecting commercial apiary locations are becoming less common in eastern North and South Dakota, changes that may have lasting impact on pollinator conservation efforts. Our study highlights how land-use change in the NGP is altering the landscape in ways that are seemingly less conducive to beekeeping. Our models can be used to guide future conservation efforts highlighted in the US national pollinator health strategy by identifying areas that support high densities of commercial apiaries and that have exhibited significant land-use changes

    The influence of spatiotemporally decoupled land use on honey bee colony health and pollination service delivery

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    Societal dependence on insects for pollination of agricultural crops has risen amidst concerns over pollinator declines. Habitat loss and lack of forage have been implicated in the decline of both managed and native pollinators. Land use changes in the Northern Great Plains of the US, a region supporting over 1 million honey bee colonies annually, have shifted away from historical grassland ecosystems bees rely on for forage toward landscapes dominated by corn, soybeans, and other row crops. We investigated how land use impacts honey bee colony population size during the growing season and subsequent colony population size for almond pollination in central California the following February.We provide estimates of how land use affects beekeeper economics by linking summer habitat with pollination service payments and later production of new colonies. Our results demonstrate that a greater presence of non-bee foraged agricultural crops surrounding apiaries in the summer results in smaller colonies by the end of the growing season. Apiaries with colonies exhibiting smaller population size in the autumn were also smaller during almond pollination the following spring; impacting the beekeeper with a reduced per-colony rental fee for pollination services and reduced potential for creating new spring colonies, based on prior growing season land use. This study highlights the downstream effects of factors driving land use decisions on the ability of beekeepers to provide robust honey bee colonies to support the pollination industry on a national scale. It also demonstrates the direct linkages between habitat in the Northern Great Plains, bee health, and pollination services rendered elsewhere in the US

    Land-use change reduces habitat suitability for supporting managed honey bee colonies in the Northern Great Plains

    Get PDF
    Human reliance on insect pollination services continues to increase even as pollinator populations exhibit global declines. Increased commodity crop prices and federal subsidies for biofuel crops, such as corn and soybeans, have contributed to rapid land-use change in the US Northern Great Plains (NGP), changes that may jeopardize habitat for honey bees in a part of the country that supports \u3e40% of the US colony stock. We investigated changes in biofuel crop production and grassland land covers surrounding ~18,000 registered commercial apiaries in North and South Dakota from 2006 to 2014. We then developed habitat selection models to identify remotely sensed land-cover and land-use features that influence apiary site selection by Dakota beekeepers. Our study demonstrates a continual increase in biofuel crops, totaling 1.2 Mha, around registered apiary locations in North and South Dakota. Such crops were avoided by commercial beekeepers when selecting apiary sites in this region. Furthermore, our analysis reveals how grasslands that beekeepers target when selecting commercial apiary locations are becoming less common in eastern North and South Dakota, changes that may have lasting impact on pollinator conservation efforts. Our study highlights how land-use change in the NGP is altering the landscape in ways that are seemingly less conducive to beekeeping. Our models can be used to guide future conservation efforts highlighted in the US national pollinator health strategy by identifying areas that support high densities of commercial apiaries and that have exhibited significant land-use changes

    Data Centric Domain Adaptation for Historical Text with OCR Errors

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    We propose new methods for in-domain and cross-domain Named Entity Recognition (NER) on historical data for Dutch and French. For the cross-domain case, we address domain shift by integrating unsupervised in-domain data via contextualized string embeddings; and OCR errors by injecting synthetic OCR errors into the source domain and address data centric domain adaptation. We propose a general approach to imitate OCR errors in arbitrary input data. Our cross-domain as well as our in-domain results outperform several strong baselines and establish state-of-the-art results. We publish preprocessed versions of the French and Dutch Europeana NER corpora

    Characteristics of Female Genital Restoration Surgery for Congenital Adrenal Hyperplasia Using a Large-scale Administrative Database

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    Objective To analyze nationwide information on the timing of surgical procedures, cost of surgery, hospital length of stay following surgery, and surgical complications of female genital restoration surgery (FGRS) in females with congenital adrenal hyperplasia (CAH). Materials and Methods We used the Pediatric Health Information System database to identify patients with CAH who underwent their initial FGRS in 2004-2014. These patients were identified by an International Classification of Diseases, Ninth Revision (ICD-9) diagnosis code for adrenogenital disorders (255.2) in addition to a vaginal ICD-9 procedure code (70.x, excluding vaginoscopy only) or perineal ICD-9 procedure code (71.x), which includes clitoral operations (71.4). Results A total of 544 (11.8%) females underwent FGRS between 2004 and 2014. Median age at initial surgery was 9.9 months (interquartile range 6.8-19.1 months). Ninety-two percent underwent a vaginal procedure, 48% underwent a clitoral procedure, and 85% underwent a perineal procedure (non-clitoral). The mean length of stay was 2.5 days (standard deviation 2.5 days). The mean cost of care was 12,258(median12,258 (median 9,558). Thirty-day readmission rate was 13.8%. Two percent underwent reoperation before discharge, and 1 (0.2%) was readmitted for a reoperation within 30 days. Four percent had a perioperative surgical complication. Conclusion Overall, 12% of girls with CAH underwent FGRS at one of a national collaborative of freestanding children's hospitals. The majority underwent a vaginoplasty as a part of their initial FGRS for CAH. Clitoroplasty was performed on less than half the patients. Overall, FGRS for CAH is performed at a median age of 10 months and has low 30-day complication and immediate reoperation rates

    PPAK Integral Field Spectroscopy survey of the Orion Nebula: Data Release

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    We present a low-resolution spectroscopic survey of the Orion nebula which data we release for public use. In this article, we intend to show the possible applications of this dataset analyzing some of the main properties of the nebula. We perform an integral field spectroscopy mosaic of an area of ~5' X 6' centered on the Trapezium region of the nebula, including the ionization front to the south-east. The analysis of the line fluxes and line ratios of both the individual and integrated spectra allowed us to determine the main characteristics of the ionization throughtout the nebula.The final dataset comprises 8182 individual spectra, which sample each one a circular area of \~2.7" diameter. The data can be downloaded as a single row-stacked spectra fits file plus a position table or as an interpolated datacube with a final sampling of 1.5"/pixel. The integrated spectrum across the field-of-view was used to obtain the main integrated properties of the nebula, including the electron density and temperature, the dust extinction, the Halpha integrated flux (after correcting for dust reddening), and the main diagnostic line ratios. The individual spectra were used to obtain line intensity maps of the different detected lines. These maps were used to study the distribution of the ionized hydrogen, the dust extinction, the electron density and temperature, and the helium and oxygen abundance...Comment: 13 pages, 8 figures, accepted for publishing in Astronomy & Astrophysic

    Electronic structure of undoped and potassium doped coronene investigated by electron energy-loss spectroscopy

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    We performed electron energy-loss spectroscopy studies in transmission in order to obtain insight into the electronic properties of potassium intercalated coronene, a recently discovered superconductor with a rather high transition temperature of about 15\,K. A comparison of the loss function of undoped and potassium intercalated coronene shows the appearance of several new peaks in the optical gap upon potassium addition. Furthermore, our core level excitation data clearly signal filling of the conduction bands with electrons.Comment: 15 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1102.328
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