7,900 research outputs found

    From graphs to tensegrity structures: Geometric and symbolic approaches

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    A form-finding problem for tensegrity structures is studied; given an abstract graph, we show an algorithm to provide a necessary condition for it to be the underlying graph of a tensegrity in Rd\mathbb{R}^d (typically d=2,3d=2,3) with vertices in general position. Furthermore, for a certain class of graphs our algorithm allows to obtain necessary and sufficient conditions on the relative position of the vertices in order to underlie a tensegrity, for what we propose both a geometric and a symbolic approach.Comment: 17 pages, 8 figures; final versio

    ϕ2\phi^2 as Dark Matter

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    In this paper we consider ϕ2\phi^2 scalar field potential as a candidate to dark matter. If it is an ultralight boson particle, it condensates like a Bose-Einstein system at very early times and forms the basic structure of the Universe. Real scalar fields collapse in equilibrium configurations that oscillate in space-time (oscillatons).The cosmological behavior of the field equations are solved using the dynamical system formalism. We use the current cosmological parameters as constraints for the present value of the scalar field. We reproduce the cosmological predictions of the standard Λ\LambdaCDM model with this model. Therefore, scalar field dark matter seems to be a good alternative to cold dark matter nature.Comment: Accepted for publication in MNRAS 11 pages, 7 figure

    A close look into an intermediate redshift galaxy using STIS

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    We present a detailed view of a galaxy at z=0.4 which is part of a large database of intermediate redshifts using high resolution images. We used the STIS parallel images and spectra to identify the object and obtain the redshift. The high resolution STIS image (0.05'') enabled us to analyse the internal structures of this galaxy. A bar along the major axis and hot-spots of star formation separated by 0.37'' (1.6 kpc) are found along the inner region of the galaxy. The analysis of the morphology of faint galaxies like this one is an important step towards estimating the epoch of formation of the Hubble classification sequence.Comment: Astronomy and Astrophysics Letter - accepte

    Higher order Borel-Pompeiu representations

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    We establish a higher order Borel-Pompeiu formula for monogenic functions associated to an arbitrary orthogonal basis (called structural set) of Euclidean space, or combinations of such structural sets

    Higher order Borel–Pompeiu representations in Clifford analysis

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    In this paper, we show that a higher order Borel–Pompeiu (Cauchy–Pompeiu) formula, associated with an arbitrary orthogonal basis (called structural set) of a Euclidean space, can be extended to the framework of generalized Clifford analysis. Furthermore, in lower dimensional cases, as well as for combinations of standard structural sets, explicit expressions of the kernel functions are derived

    El papel de la matemática en el proceso educativo inicial

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    A short analysis of the educational values of Mathematics and of the main defects that can be observed in the current trends in Spanish primary and secondary schools, together with some remedial suggestions
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