534 research outputs found

    An empirical relationship between the prey density and predatory efficiency of Gambusia affinis

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    Larval density of Culex fatigans essentially influences the predatory rate of the mosquito-fish Gambusia affinis. The feeding rate of the fish gradually increases up to a maximum value at intermediate prey densities beyond which there is an asymptotic saturation in the feeding rate. The relationship is represented by an empirical equation which helps in the prediction of the ideal stocking rate of the fish in natural systems. © 1977 Birkhäuser Verlag

    Laboratory studies on food intake, growth and conversion efficiency of Palaemon lamarrei in relation to body size

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    The effects of body size on the food intake, growth and conversion efficiency of the freshwater prawn Palaemon lamarrei have been studied. In captivity, fed on a restricted diet of the muscles of the fish Gambusia affinis, moulting in these prawns occurred once in 18 ± 5 days at a temperature of 26 ± 1°C. The importance of these cast moults, contributing a sizable amount of organic matter to the detritus deposit of freshwater habitats has been indicated. In a log-log system, both food intake and growth per day, represented as a percentage of body weight, showed an inverse relationship to the body size. Animals in the size range of 600-800 mg exhibited the highest conversion efficiency. The present study indicates that these prawns can be successfully reared and grown under laboratory conditions. © 1977

    Food intake, growth, food conversion, and body composition of catfish exposed to different salinities

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    The effects of different salinities (0, 2, 4, 6 and 10‰) on food intake, growth, food conversion, and body composition of the freshwater catfish Mystus vittatus (Bloch) were studied. Under a restricted feeding schedule daily intake of food was found to be salinity dependent. Fish reared in 10‰ consumed more Tubifex tubifex, converted less efficiently and displayed poor growth as compared to individuals reared in fresh water. Fish flesh production decreased from 483 g (fresh water) to 177 g (10‰ salinity) as the salinity was increased. Water content of the fish was found to decrease with increase in salinity, while maximum ash (25.56%) and fat (42.25%) were exhibited by fish reared in 10‰ salinity. © 1979

    Growth rate and conversion efficiency of the air-breathing catfish, Heteropneustes fossilis, in relation to ration size

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    Effects of different feeding rates (0-20% live body weight) on food intake, growth and conversion efficiency of Heteropneustes fossilis were studied using the oligochaete worm Tubifex tubifex as food. An amount of worm substance equivalent to 12.73% live body weight/fish day-1 represents the maximum amount which a 4.015 ± 0.340-g H. fossilis can consume under laboratory conditions. Geometrically derived feeding rations of 12, 40 and 130 mg/g live fish day-1 represent the maintenance, optimum and maximum levels for H. fossilis. The SDA (specific dynamic action) increased from 14 mg/g day-1 at optimum to 70 mg/g day-1 at maximum feeding rate. © 1979

    Axial-flexural coupled vibration and buckling of composite beams using sinusoidal shear deformation theory

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    A finite element model based on sinusoidal shear deformation theory is developed to study vibration and buckling analysis of composite beams with arbitrary lay-ups. This theory satisfies the zero traction boundary conditions on the top and bottom surfaces of beam without using shear correction factors. Besides, it has strong similarity with Euler–Bernoulli beam theory in some aspects such as governing equations, boundary conditions, and stress resultant expressions. By using Hamilton’s principle, governing equations of motion are derived. A displacement-based one-dimensional finite element model is developed to solve the problem. Numerical results for cross-ply and angle-ply composite beams are obtained as special cases and are compared with other solutions available in the literature. A variety of parametric studies are conducted to demonstrate the effect of fiber orientation and modulus ratio on the natural frequencies, critical buckling loads, and load-frequency curves as well as corresponding mode shapes of composite beams

    UniHI 7: an enhanced database for retrieval and interactive analysis of human molecular interaction networks.

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    Unified Human Interactome (UniHI) (http://www.unihi.org) is a database for retrieval, analysis and visualization of human molecular interaction networks. Its primary aim is to provide a comprehensive and easy-to-use platform for network-based investigations to a wide community of researchers in biology and medicine. Here, we describe a major update (version 7) of the database previously featured in NAR Database Issue. UniHI 7 currently includes almost 350,000 molecular interactions between genes, proteins and drugs, as well as numerous other types of data such as gene expression and functional annotation. Multiple options for interactive filtering and highlighting of proteins can be employed to obtain more reliable and specific network structures. Expression and other genomic data can be uploaded by the user to examine local network structures. Additional built-in tools enable ready identification of known drug targets, as well as of biological processes, phenotypes and pathways enriched with network proteins. A distinctive feature of UniHI 7 is its user-friendly interface designed to be utilized in an intuitive manner, enabling researchers less acquainted with network analysis to perform state-of-the-art network-based investigations

    Design of PI and Fuzzy Logic Controllers for Distribution Static Compensator

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    This paper presents study of distribution static compensator (D-STATCOM) for compensation of reactive power, harmonic distortion mitigation and load balancing in three phase three wire nonlinear load distribution system. The proposed control algorithm is developed based on synchronous reference frame theory using PI and FUZZY logic controller. The obtained reference current signal from control algorithm is compared in hysteresis band current controller for better switching of D-STATCOM. The performance of DSTATCOM with PI and fuzzy logic controller is also analysed and compared for DC voltage regulation and harmonic distortion mitigation .The proposed method is provided effective compensation for reactive power, harmonic distortion mitigation and load voltage balancing. The simulation results are obtained using MATLAB/SIMULINK soft ware

    Real-space local polynomial basis for solid-state electronic-structure calculations: A finite-element approach

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    We present an approach to solid-state electronic-structure calculations based on the finite-element method. In this method, the basis functions are strictly local, piecewise polynomials. Because the basis is composed of polynomials, the method is completely general and its convergence can be controlled systematically. Because the basis functions are strictly local in real space, the method allows for variable resolution in real space; produces sparse, structured matrices, enabling the effective use of iterative solution methods; and is well suited to parallel implementation. The method thus combines the significant advantages of both real-space-grid and basis-oriented approaches and so promises to be particularly well suited for large, accurate ab initio calculations. We develop the theory of our approach in detail, discuss advantages and disadvantages, and report initial results, including the first fully three-dimensional electronic band structures calculated by the method.Comment: replacement: single spaced, included figures, added journal referenc
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