1,416 research outputs found

    Les Isopodes terrestres et cavernicoles de la Catalogne

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    Sur la présence en Catalogne du genre Libanonethes (Crustacés; Isopodes; Oniscoïdes)

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    A Preliminary Study of the Separation of the Copper Sulfides from Sphalerite and the Effect of Certain Reagents on Some of the Pure Copper Minerals in Synthetic Mixtures

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    The problem of separating the copper sulfide minerals from sphalerite, in copper - zinc ores, has been a difficult one. This is largely due to the lack of adequate research and the small amount of data obtainable on the behavior of copper and zinc sulfide minerals in flotation circuits

    Land Use Changes and Pheasant Declines in Eastern South Dakota

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    Changes in pheasant (Phasianus colchicus) nesting habitat were investigated on Windsor Township, Brookings County, South Dakota. The population was censused, nesting densities determined, cover was mapped, and an interspersion index determined in 197 7 and 1978. Comparison to a similar study conducted in 1958 and 1959 indicated a decrease in pheasant numbers of 93% for crow counts and 94% in brood counts. Nesting densities decreased by 96%. Pheasant nests were found in about the same proportions per cover type for the two time periods. Hatching success, clutch size, rates of abandonment, and nest destruction were also similar. Nesting habitat occurred on 70% of the study area in 1958, 62% in 1959, 74% in 197 7, and 66% in 1978. The mean field size was 6.7 ha in 1958, 6.9 ha in 1959, 10.2 ha in 197 7, and 8.0 ha in 1978. The interspersion index decreased by 4% from 1958-59 to 197 7-78. Although land use changes have resulted in reduction of habitat in twenty years the amount of habitat reduction does not compare to the reduction in pheasant numbers. Factors such as cover quality, which could not be measured quantitatively, may be more responsible for decreasing the pheasant population in eastern South Dakota than cover quantity

    The Methyltransferases PRMT4/CARM1 and PRMT5 Control Differentially Myogenesis in Zebrafish

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    In vertebrates, skeletal myogenesis involves the sequential activation of myogenic factors to lead ultimately to the differentiation into slow and fast muscle fibers. How transcriptional co-regulators such as arginine methyltransferases PRMT4/CARM1 and PRMT5 control myogenesis in vivo remains poorly understood. Loss-of-function experiments using morpholinos against PRMT4/CARM1 and PRMT5 combined with in situ hybridization, quantitative polymerase chain reaction, as well as immunohistochemistry indicate a positive, but differential, role of these enzymes during myogenesis in vivo. While PRMT5 regulates myod, myf5 and myogenin expression and thereby slow and fast fiber formation, PRMT4/CARM1 regulates myogenin expression, fast fiber formation and does not affect slow fiber formation. However, our results show that PRMT4/CARM1 is required for proper slow myosin heavy chain localization. Altogether, our results reveal a combinatorial role of PRMT4/CARM1 and PRMT5 for proper myogenesis in zebrafish

    SAGA: Sparse And Geometry-Aware non-negative matrix factorization through non-linear local embedding

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    International audienceThis paper presents a new non-negative matrix factorization technique which (1) allows the decomposition of the original data on multiple latent factors accounting for the geometrical structure of the manifold embedding the data; (2) provides an optimal representation with a controllable level of sparsity; (3) has an overall linear complexity allowing handling in tractable time large and high dimensional datasets. It operates by coding the data with respect to local neighbors with non-linear weights. This locality is obtained as a consequence of the simultaneous sparsity and convexity constraints. Our method is demonstrated over several experiments, including a feature extraction and classification task, where it achieves better performances than the state-of-the-art factorization methods, with a shorter computational time

    A fast GNU method to draw accurate scientific illustrations for taxonomy

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    Nowadays only digital figures are accepted by the most important journals of taxonomy. These may be produced by scanning conventional drawings, made with high precision technical ink-pens, which normally use capillary cartridge and various line widths. Digital drawing techniques that use vector graphics, have already been described in literature to support scientists in drawing figures and plates for scientific illustrations; these techniques use many different software and hardware devices. The present work gives step-by-step instructions on how to make accurate line drawings with a new procedure that uses bitmap graphics with the GNU Image Manipulation Program (GIMP). This method is noteworthy: it is very accurate, producing detailed lines at the highest resolution; the raster lines appear as realistic ink-made drawings; it is faster than the traditional way of making illustrations; everyone can use this simple technique; this method is completely free as it does not use expensive and licensed software and it can be used with different operating systems. The method has been developed drawing figures of terrestrial isopods and some examples are here given
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