2,042 research outputs found

    Review of aquaculture and fish consumption in Bangladesh

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    Fish play a crucial role in the Bangladeshi diet, providing more than 60% of animal source food, representing a crucial source of micro-nutrients, and possessing an extremely strong cultural attachment. Fish (including shrimp and prawn) is the second most valuable agricultural crop, and its production contributes to the livelihoods and employment of millions. The culture and consumption of fish therefore has important implications for national food and nutrition security, poverty and growth. This review examines the current state of knowledge on the aquaculture sector and fish consumption in Bangladesh, based on extensive analysis of secondary sources (including unpublished data unavailable elsewhere), consultation with various experts and specially conducted surveys. The review is comprised of three sections. Section 1 describes the main systems of aquaculture production in terms of their technical and social characteristics and outputs. Section 2 addresses issues relating to seed and feed. The final section analyses fish consumption patterns and demand, and attempts to estimate the volumes of fish produced from a range of sources.Food fish, Aquaculture, Food consumption, Fish consumption, Pond culture, Rice field aquaculture, Bangladesh,

    Acoustic field coherence in four-dimensionally variable shallow water environments : estimation using co-located horizontal and vertical line arrays

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    Underwater Acoustic Measurements (UAM) 2nd International Conference & Exhibition on "Underwater Acoustic Measurements: Technologies & Results," 25-29 June 2007, Heraklion, Crete, Greece.The implementation of two- and three-dimensional acoustic receiver arrays is challenging in the ocean environment. Fixed geometry and connectivity can only be built and maintained at great expense. However, such ideal arrays can be very powerful for signal detection, classification, and tracking, although many of the signal-processing methods employed are subject to constraints of acoustic field temporal and spatial coherence. Thus, understanding the processes at work determining coherence is essential because system effectiveness may then be predictable from environmental parameter input. To study acoustic fields and coherence over finite aperture, the research community has recently taken steps to enable routine use of co-located horizontal and vertical line arrays, typically arranged in the shape of the Roman letter L (or Greek ), with the horizontal leg on the seafloor. This is a small subset of all possible geometries, but it enables measurements of acoustic field coherence not possible with single line arrays. Here, new L-array measurements made in the SW06 field program are used to measure coherence and test coherence predictions via joint analysis of vertical and horizontal line array receptions. Impulsive mode arrivals (including mode multipath) from fixed sources will be estimated using the vertical array. Signals on the horizontal array, which is neither broadside nor endfire, will be compared with signals synthesized using the mode arrivals to estimate azimuthal decorrelation effects. Results can be compared with coherence estimates from computational and theoretical studies

    Mesospheric observations with the EISCAT UHF radar during polar cap absorption events: <br>3. Comparison with simultaneous EISCAT VHF measurements

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    International audienceMesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the first comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, co-located observations by the two radars. VHF spectra observed with a vertical antenna were found to be significantly narrower than model predictions, in agreement with earlier UHF results. For antenna pointing directions that were significantly away from the vertical, the wider VHF radar beam gave rise to broadening of the observed spectra due to vertical shears in the horizontal wind. In this configuration, UHF spectral measurements were found to be more suitable for aeronomical applications. Both radar systems provide consistent and reliable estimates of the neutral wind. Spectral results using both the multipulse and pulse-to-pulse schemes were intercompared and their suitability for application to combined mesosphere ? lower thermosphere studies investigated

    A Bovine Monstra Duplica

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    Double monsters are pathological deviants from identical twins, in that the embryos are joined in some manner. The embryos may be symmetrically united and developed, or one of the individuals may he arrested in its development. In describing the morphological relationships of the calf of this study, the right and left sides will refer to the animal\u27s right and left respectively. From a superficial examination of this specimen it appears to be a single-bodied calf with two heads, an extra leg with two hooves protruding from the hack a short distance caudal to the vertex of the two heads, and two tails. These facts indicate that there are two animals in this union, hut this indication is not carried out on the ventral surface as there are only four teats and one opening for the umbilical vessels to enter the body

    Elastic Pekeris waveguide normal mode solution comparisons against laboratory data

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    Following the derivation presented by Press and Ewing [Geophysics 15, 426-446 (1950)], a normal mode solution for the Pekeris waveguide problem with an elastic bottom is outlined. The analytic solution is benchmarked against data collected in an experiment performed at the Naval Research Laboratory [Collis et al., J. Acoust. Soc. Am. 122, 1987-1993 (2007)]. Comparisons reveal a close match between the analytic solution and experimental data. Results are strongly dependent on the accuracy of the horizontal wavenumbers for the modes, and horizontal wavenumber spectra are compared against those from the experimental data. (C) 2012 Acoustical Society of AmericaNational Science Foundation Division of Graduate Education [DGE-0638719

    A Temporal Map in Geostationary Orbit: The Cover Etching on the EchoStar XVI Artifact

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    Geostationary satellites are unique among orbital spacecraft in that they experience no appreciable atmospheric drag. After concluding their respective missions, geostationary spacecraft remain in orbit virtually in perpetuity. As such, they represent some of human civilization's longest lasting artifacts. With this in mind, the EchoStar XVI satellite, to be launched in fall 2012, will play host to a time capsule intended as a message for the deep future. Inspired in part by the Pioneer Plaque and Voyager Golden Records, the EchoStar XVI Artifact is a pair of gold-plated aluminum jackets housing a small silicon disc containing one hundred photographs. The Cover Etching, the subject of this paper, is etched onto one of the two jackets. It is a temporal map consisting of a star chart, pulsar timings, and other information describing the epoch from which EchoStar XVI came. The pulsar sample consists of 13 rapidly rotating objects, 5 of which are especially stable, having spin periods < 10 ms and extremely small spindown rates. In this paper, we discuss our approach to the time map etched onto the cover and the scientific data shown on it; and we speculate on the uses that future scientists may have for its data. The other portions of the EchoStar XVI Artifact will be discussed elsewhere.Comment: Accepted for publication in Astronomical Journa

    The Association Between Work-Related Rumination and Executive Function Using the Behavior Rating Inventory of Executive Function

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    This is the final version. Available on open access from Frontiers Media via the DOI in this recordData Availability Statement: The datasets generated for this study are available on request to the corresponding author.Work-related rumination has been associated with a number of health complaints, however, little is known about the underlying factors associated with rumination. Previous work using proxy measures of executive function showed work-related rumination to be negatively associated with executive function. In this paper, we report two studies that examined the association between work-related rumination and executive function utilizing an ecological valid measure of executive function: the Behavior Rating Inventory of Executive Function (BRIEF-A, Roth et al., 2005). In study 1 (N = 63), high, relative to low work-related ruminators, were found to demonstrate lower executive function skills, in eight of the nine subscales of the BRIEF. The aim of study 2 (N = 237) was to identify, the key executive function subscale/s associated with work-related rumination. Controlling for known factors associated with work-related rumination (fatigue and sleep), regression analysis identified the behavioral regulation subscale "shift" as the key predictor within the model. Shift relates to our ability to switch attention, to think about different solutions, and dealing with and accepting change. It was concluded that these findings lend support for future research to develop interventions for enhancing shift ability, as an aid to reduce work-related ruminative thinking

    Observed limiting cases of horizontal field coherence and array performance in a time-varying internal wavefield

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    Author Posting. © Acoustical Society of America, 2008. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 124 (2008): EL97-EL103, doi:10.1121/1.2947630.Using a moored source and horizontal/vertical line array combination, horizontal coherence properties of high signal to noise ratio (>=20 dB) 100–1600 Hz signals have been measured. Internal waves in the area of the measurement created moving episodic sound-speed anomaly structures, influencing coherence length. Measured horizontal coherence scales for 100 Hz ranged from 5 to 20 acoustic wavelengths, and were inversely related to the sound-speed anomaly strength. Horizontal field properties were compared with fields computed using modal decompositions of the vertical signals. The comparison allows azimuthal field coherence properties to be studied apart from normal-mode interference effects.This work was funded by grants to Boston University and the Woods Hole Oceanographic Institution from the Ocean Acoustics Program at the U.S. Office of Naval Research, including an ONR Postdoctoral Fellowship award to the first author
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