32,582 research outputs found

    Barbaetis: A New Genus of Eastern Nearctic Mayflies (Ephemeroptera: Baetidae)

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    The new genus Barbaetis Waltz and McCafferty, and new species Barbaetis benfieldi Kennedy are described from larvae collected from the New River, Virginia. Barbaetis is easily told from Baetis by the presence of procoxal osmobranchia. Cladistics of B. benfieldi, related Pseudocloeon species, and the lutheri and pavidus complexes of Baetis are presented and indicate the need for further taxonomic revision. The habitat of B. benfieldi is described in terms of several ecological parameters. The new species demonstrates a univoltine life history with postembryonic development restricted to a short springtime period

    Some remarks on the isoperimetric problem for the higher eigenvalues of the Robin and Wentzell Laplacians

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    We consider the problem of minimising the kkth eigenvalue, k2k \geq 2, of the (pp-)Laplacian with Robin boundary conditions with respect to all domains in RN\mathbb{R}^N of given volume MM. When k=2k=2, we prove that the second eigenvalue of the pp-Laplacian is minimised by the domain consisting of the disjoint union of two balls of equal volume, and that this is the unique domain with this property. For p=2p=2 and k3k \geq 3, we prove that in many cases a minimiser cannot be independent of the value of the constant α\alpha in the boundary condition, or equivalently of the volume MM. We obtain similar results for the Laplacian with generalised Wentzell boundary conditions Δu+βuν+γu=0\Delta u + \beta \frac{\partial u}{\partial \nu} + \gamma u = 0.Comment: 16 page

    An Optimal Dimensionality Multi-shell Sampling Scheme with Accurate and Efficient Transforms for Diffusion MRI

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    This paper proposes a multi-shell sampling scheme and corresponding transforms for the accurate reconstruction of the diffusion signal in diffusion MRI by expansion in the spherical polar Fourier (SPF) basis. The sampling scheme uses an optimal number of samples, equal to the degrees of freedom of the band-limited diffusion signal in the SPF domain, and allows for computationally efficient reconstruction. We use synthetic data sets to demonstrate that the proposed scheme allows for greater reconstruction accuracy of the diffusion signal than the multi-shell sampling schemes obtained using the generalised electrostatic energy minimisation (gEEM) method used in the Human Connectome Project. We also demonstrate that the proposed sampling scheme allows for increased angular discrimination and improved rotational invariance of reconstruction accuracy than the gEEM schemes.Comment: 4 pages, 4 figures presented at ISBI 201

    Scattering of Woods-Saxon Potential in Schrodinger Equation

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    The scattering solutions of the one-dimensional Schrodinger equation for the Woods-Saxon potential are obtained within the position-dependent mass formalism. The wave functions, transmission and reflection coefficients are calculated in terms of Heun's function. These results are also studied for the constant mass case in detail.Comment: 14 page

    Arkansas Cotton Variety Test 2012

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    The primary goal of the Arkansas Cotton Variety Test is to provide unbiased data regarding the agronomic performance of cotton varieties and advanced breeding lines in the major cotton-growing areas of Arkansas. This information helps seed companies establish marketing strategies and assists producers in choosing varieties to plant

    Hypermedia design for enriching conceptual understanding in chemistry

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    Hypermedia and Interactive Multimedia (IMM) are part of the lexicon of descriptive terms currently being used for Computer Aided Learning (CAL). In the literature, universally accepted meanings of these terms have yet to be agreed upon, however, most researchers in the field agree that hypermedia and IMM have the following general aspects in common