416 research outputs found

    Filamentous Fungi Present in the External Mucus of Gizzard Shad (Dorosoma cepedianum)

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    The mucus layers of 30 gizzard shad (Dorosoma cepedianum) from the Lake Charleston side channel reservoir were sampled to identify what fungi or fungal spores were present. The fish sampled had a mean length of 171 mm, a mean weight of 41 g, and a mean age of 2.1 years. Hemp seed, fish scale, and polycell-gel substrates were examined, and four genera of fungi were identified. Fusarium was most frequently encountered, followed by Pythium, Allomyces, and Saprolegnia, respectively. Older fish (2.5 and 3.5 yrs) had a greater diversity of associated fungi than did younger fish (1.5 yrs), probably due to their benthic feeding habits and greater reproductive stress

    Low cost real time interactive analysis system

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    Efforts continue to develop a low cost real time interactive analysis system for the reception of satellite data. A multi-purpose ingest hardware software frame formatter was demonstrated for GOES and TIROS data and work is proceeding on extending the capability to receive GMS data. A similar system was proposed as an archival and analysis system for use with INSAT data and studies are underway to modify the system to receive the planned SeaWiFS (ocean color) data. This system was proposed as the core of a number of international programs in support of U.S. AID activities. Systems delivered or nearing final testing are listed

    Preliminary Studies Leading Toward the Development of a LIDAR Bathymetry Mapping Instrument

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    The National Aeronautics and Space Administration (NASA) at Goddard Space Flight Center (GSFC) has developed a laser ranging device (LIDAR) which provides accurate and timely data of earth features. NASA/GSFC recently modified the sensor to include a scanning capability to produce LIDAR swaths. They have also integrated a Global Positioning System (GPS) and an Inertial Navigation System (INS) to accurately determine the absolute aircraft location and aircraft attitude (pitch, yaw, and roll), respectively. The sensor has been flown in research mode by NASA for many years. The LIDAR has been used in different configurations or modes to acquire such data as altimetry (topography), bathymetry (water depth), laser-induced fluorosensing (tracer dye movements, oil spills and oil thickness, chlorophyll and plant stress identification), forestry, and wetland discrimination studies. NASA and HARC are developing a commercial version of the instrument for topographic mapping applications. The next phase of the commercialization project will be to investigate other applications such as wetlands mapping and coastal bathymetry. In this paper we report on preliminary laboratory measurements to determine the feasibility of making accurate depth measurements in relatively shallow water (approximately 2 to 6 feet deep) using a LIDAR system. The LIDAR bathymetry measurements are relatively simple in theory. The water depth is determined by measuring the time interval between the water surface reflection and the bottom surface reflection signals. Depth is then calculated by dividing by the index of refraction of water. However, the measurements are somewhat complicated due to the convolution of the water surface return signal with the bottom surface return signal. Therefore in addition to the laboratory experiments, computer simulations of the data were made to show these convolution effects in the return pulse waveform due to: (1) water depth, and (2) changes in bottom surface reflectivity
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