5,701 research outputs found

    Foraging Behavior of Swainson\u27s Thrushes (Catharus ustulatus) During Spring Migration through Arkansas

    Get PDF
    Foraging behavior of Swainson’s Thrushes on spring migration was studied in western Arkansas in the spring of 2013 and 2014. Observations were made in two forested field sites, one of them urban and the other suburban. The former had a significantly higher woody stem area (cm2) than the latter. For each foraging observation, the following three parameters were noted: Foraging Stratum (Ground, Shrub, Sapling, Sub canopy, and Canopy); Foraging Substrate (Ground/Litter, Herb, Foliage, Bark, and Air); and Foraging Maneuver (Glean, Probe, Dive/Glean, Hover, Jump Hover, and Hawking). We tested the hypotheses that these foraging variables differed significantly between the urban and suburban sites, and between the two years. These hypotheses were rejected for all three parameters. The consolidated data from both the sites and years revealed that a significantly higher proportion (67%) of the observations were on the Ground stratum, compared to the Shrub (13.7%) and Sapling strata (13%). Similarly, a significantly higher proportion (66%) of the foraging substrate used was Ground/Litter, followed by Foliage (16.7%) and Bark (15.8%). Gleaning was the most common foraging maneuver used (71.5%), and was significantly higher than Probing (12.3%) and Dive Gleaning (8.4%)

    Extended flight evaluation of a near-term pitch active control system

    Get PDF
    Fuel savings can be achieved by moving the center of gravity of an aircraft aft which reduces the static stability margin and consequently the trim drag. However, flying qualities of an aircraft with relaxed static stability can be significantly degraded. The flying qualities can be restored by using a pitch active control system (PACS). This report documents the work accomplished during a follow-on program (see NASA CR-165951 for initial program report) to perform extended flight tests of a near-term PACS. The program included flying qualities analyses, piloted flight simulation tests, aircraft preparation and flight tests to demonstrate that the near-term PACS provided good flying qualities within the linear static stability envelope to a negative 3% static stability margin

    Improved analysis of propylene oxide, propylene chlorohydrin and propylene bromohydrin: Presentation

    Get PDF
    The benefits and deficiencies of several methods of analysis for PPO and PXH, including the aqueous extraction used in ASTA method 23.1 and the MTBE extraction method previously reported by the authors, will be discussed. Novel methods utilizing dynamic headspace extraction and solid phase microextraction (SPME) will also be reported with particular emphasis on preventing artefactual effects. Preliminary experiments have found that dynamic headspace sampling can lower detection limits by up to 3 orders of magnitude.The benefits and deficiencies of several methods of analysis for PPO and PXH, including the aqueous extraction used in ASTA method 23.1 and the MTBE extraction method previously reported by the authors, will be discussed. Novel methods utilizing dynamic headspace extraction and solid phase microextraction (SPME) will also be reported with particular emphasis on preventing artefactual effects. Preliminary experiments have found that dynamic headspace sampling can lower detection limits by up to 3 orders of magnitude

    Apollo experience report: Development of guidance targeting techniques for the command module and launch vehicle

    Get PDF
    The development of the guidance targeting techniques for the Apollo command module and launch vehicle is discussed for four types of maneuvers: (1) translunar injection, (2) translunar midcourse, (3) lunar orbit insertion, and (4) return to earth. The development of real-time targeting programs for these maneuvers and the targeting procedures represented are discussed. The material is intended to convey historically the development of the targeting techniques required to meet the defined target objectives and to illustrate the solutions to problems encountered during that development

    Astronomy in the Cloud: Using MapReduce for Image Coaddition

    Full text link
    In the coming decade, astronomical surveys of the sky will generate tens of terabytes of images and detect hundreds of millions of sources every night. The study of these sources will involve computation challenges such as anomaly detection and classification, and moving object tracking. Since such studies benefit from the highest quality data, methods such as image coaddition (stacking) will be a critical preprocessing step prior to scientific investigation. With a requirement that these images be analyzed on a nightly basis to identify moving sources or transient objects, these data streams present many computational challenges. Given the quantity of data involved, the computational load of these problems can only be addressed by distributing the workload over a large number of nodes. However, the high data throughput demanded by these applications may present scalability challenges for certain storage architectures. One scalable data-processing method that has emerged in recent years is MapReduce, and in this paper we focus on its popular open-source implementation called Hadoop. In the Hadoop framework, the data is partitioned among storage attached directly to worker nodes, and the processing workload is scheduled in parallel on the nodes that contain the required input data. A further motivation for using Hadoop is that it allows us to exploit cloud computing resources, e.g., Amazon's EC2. We report on our experience implementing a scalable image-processing pipeline for the SDSS imaging database using Hadoop. This multi-terabyte imaging dataset provides a good testbed for algorithm development since its scope and structure approximate future surveys. First, we describe MapReduce and how we adapted image coaddition to the MapReduce framework. Then we describe a number of optimizations to our basic approach and report experimental results comparing their performance.Comment: 31 pages, 11 figures, 2 table

    Transient x-ray diffraction used to diagnose shock compressed Si crystals on the Nova laser

    Get PDF
    Transient x-ray diffraction is used to record time-resolved information about the shock compression of materials. This technique has been applied on Nova shock experiments driven using a hohlraum x-ray drive. Data were recorded from the shock release at the free surface of a Si crystal, as well as from Si at an embedded ablator/Si interface. Modeling has been done to simulate the diffraction data incorporating the strained crystal rocking curves and Bragg diffraction efficiencies. Examples of the data and post-processed simulations are presented

    A depolarization and attenuation experiment using the CTS satellite. Volume 1: Experiment description

    Get PDF
    An experiment for measuring precipitation attenuation and depolarization on the Communications Technology Satellite (CTS) 11.7 GHz downlink is described. Attenuation and depolarization of the signal received from the spacecraft is monitored on a 24 hour basis. Data is correlated with ground weather conditions. Theoretical models for millimeter wave propagation through rain are refined for maximum agreement with observed data. Techniques are developed for predicting and mimimizing the effects of rain scatter and depolarization on future satellite communication systems

    A 20 Ghz Depolarization Experiment Using the ATS-6 Satellite

    Get PDF
    A depolarization experiment using the 20 GHz downlink from the ATS-6 satellite was described. The following subjects were covered: (1) an operational summary of the experiment, (2) a description of the equipment used with emphasis on improvements made to the signal processing receiver used with the ATS-5 satellite, (3) data on depolarization and attenuation in one snow storm and two rain storms at 45 deg elevation, (4) data on low angle propagation, (5) conclusions about depolarization on satellite paths, and (6) recommendations for the depolarization portion of the CTS experiment

    Influenza vaccination during pregnancy: A qualitative study of the knowledge, attitudes, beliefs, and practices of general practitioners in Central and South-Western Sydney

    Full text link
    Background: Pregnant women have an increased risk of influenza complications. Influenza vaccination during pregnancy is safe and effective, however coverage in Australia is less than 40%. Pregnant women who receive a recommendation for influenza vaccination from a health care provider are more likely to receive it, however the perspectives of Australian general practitioners has not previously been reported. The aim of the study was to investigate the knowledge, attitudes, beliefs, and practices of general practitioners practicing in South-Western Sydney, Australia towards influenza vaccination during pregnancy. Methods. A qualitative descriptive study was conducted, with semi-structured interviews completed with seventeen general practitioners in October 2012. A thematic analysis was undertaken by four researchers, and transcripts were analysed using N-Vivo software according to agreed codes. Results: One-third of the general practitioners interviewed did not consider influenza during pregnancy to be a serious risk for the mother or the baby. The majority of the general practitioners were aware of the government recommendations for influenza vaccination during pregnancy, but few general practitioners were confident of their knowledge about the vaccine and most felt they needed more information. More than half the general practitioners had significant concerns about the safety of influenza vaccination during pregnancy. Their practices in the provision of the vaccine were related to their perception of risk of influenza during pregnancy and their confidence about the safety of the vaccine. While two-thirds reported that they are recommending influenza vaccination to their pregnant patients, many were adopting principles of patient-informed choice in their approach and encouraged women to decide for themselves whether they would receive the vaccine. Conclusions: General practitioners have varied knowledge, attitudes, and beliefs about influenza vaccination during pregnancy, which influence their practices. Addressing these could have a significant impact on improving vaccine uptake during pregnancy. © 2014 Maher et al.; licensee BioMed Central Ltd
    corecore