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Search Results: 1 - 10 of 224216 matches for " P. González Gallego "
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Endoftalmitis postquirúrgicas: Elaboración de guías de buena práctica clínica Post-operative endophthalmitis: Developing guidelines for good clinical practice
P. González Gallego
Archivos de la Sociedad Espa?ola de Oftalmología , 2004,
Abstract:
Las revistas de economía y empresa en la Universidad de León: uso y calidad*
Gallego Lorenzo,Josefa; González Pérez,Bego?a;
Revista Interamericana de Bibliotecología , 2009,
Abstract: this paper analyzes the impact factor, which is published in the journal citation report of the social science citation index, and the use of the economics and business scientific journals which have been accessible by means of emerald, science direct, springerlink y wiley interscience at the university of leon in 2003 and 2004. the objective is to verify if economics and business journals which have higher relevance, that is, the journals which have a higher impact factor, are the most used by the by the university community. because of this, both concepts are related in order to know if the impact factor has influence on the journals use.
Deformation of finite morphisms and smoothing of ropes
F. Javier Gallego,Miguel González,Bangere P. Purnaprajna
Mathematics , 2005,
Abstract: In this article we present a unified way to smooth certain multiple structures called ropes on smooth varieties. We prove that most ropes of arbitrary multiplicity, supported on smooth curves can be smoothed. By a rope being smoothable we mean that the rope is the flat limit of a family of smooth, irreducible curves. To construct a smoothing, we connect, on the one hand, deformations of a finite morphism to projective space and, on the other hand, morphisms from a rope to projective space. We also prove a general result of independent interest, namely, finite covers onto smooth irreducible curves embedded in projective space can be deformed to a family of $1:1$ maps. We apply our general theory to prove the smoothing of ropes of \multiplicity 3 on $\bold P^1$. Even though this article focuses on ropes of dimension 1, our method yields a general approach to deal with the smoothing of ropes of higher dimension.
An infinitesimal condition to deform a finite morphism to an embedding
Francisco Javier Gallego,Miguel González,Bangere P. Purnaprajna
Mathematics , 2010,
Abstract: In this article we give a sufficient condition for a morphism $\varphi$ from a smooth variety $X$ to projective space, finite onto a smooth image, to be deformed to an embedding. This result puts some theorems on deformation of morphisms of curves and surfaces such as $K3$ and general type, obtained by ad hoc methods, in a new, more conceptual light. One of the main interests of our result is to apply it to the construction of smooth varieties in projective space with given invariants. We illustrate this by using our result to construct canonically embedded surfaces with $c_1^2=3p_g-7$ and derive some interesting properties of their moduli spaces. Another interesting application of our result is the smoothing of ropes. We obtain a sufficient condition for a rope embedded in projective space to be smoothable. As a consequence, we prove that canonically embedded carpets satisfying certain conditions can be smoothed. We also give simple, unified proofs of known theorems on the smoothing of $1$--dimensional ropes and $K3$ carpets. Our condition for deforming $\varphi$ to an embedding can be stated very transparently in terms of the cohomology class of a suitable first order infinitesimal deformation of $\varphi$. It holds in a very general setting (any $X$ of arbitrary dimension and any $\varphi$ unobstructed with an algebraic formally semiuniversal deformation). The simplicity of the result can be seen for instance when we specialize it to the case of curves.
Smoothable locally Cohen--Macaulay and non Cohen--Macaulay multiple structures on curves
Francisco Javier Gallego,Miguel González,Bangere P. Purnaprajna
Mathematics , 2012,
Abstract: In this article we show that a wide range of multiple structures on curves arise whenever a family of embeddings degenerates to a morphism $\varphi$ of degree $n$. One could expect to see, when an embedding degenerates to such a morphism, the appearance of a locally Cohen-Macaulay multiple structure of certain kind (a so-called rope of multiplicity $n$). We show that this expectation is naive and that both locally Cohen-Macaulay and non Cohen-Macaulay multiple structures might occur in this situation. In seeing this we find out that many multiple structures can be smoothed. When we specialize to the case of double structures we are able to say much more. In particular, we find numerical conditions, in terms of the degree and the arithmetic genus, for the existence of many smoothable double structures. Also, we show that the existence of these double structures is determined, although not uniquely, by the elements of certain space of vector bundle homomorphisms, which are related to the first order infinitesimal deformations of $\varphi$. In many instances, we show that, in order to determine a double structure uniquely, looking merely at a first order deformation of $\varphi$ is not enough; one needs to choose also a formal deformation.
Deformation of canonical morphisms and the moduli of surfaces of general type
F. J. Gallego,M. González,B. P. Purnaprajna
Mathematics , 2010, DOI: 10.1007/s00222-010-0257-8
Abstract: In this article we study the deformation of finite maps and show how to use this deformation theory to construct varieties with given invariants in a projective space. Among other things, we prove a criterion that determines when a finite map can be deformed to a one--to--one map. We use this criterion to construct new simple canonical surfaces with different $c_1^2$ and $\chi$. Our general results enable us to describe some new components of the moduli of surfaces of general type. We also find infinitely many moduli spaces $\mathcal M_{(x',0,y)}$ having one component whose general point corresponds to a canonically embedded surface and another component whose general point corresponds to a surface whose canonical map is a degree 2 morphism.
On the deformations of canonical double covers of minimal rational surfaces
Francisco Javier Gallego,Miguel González,Bangere P. Purnaprajna
Mathematics , 2010,
Abstract: The purpose of this article is to study the deformations of smooth surfaces $X$ of general type whose canonical map is a finite, degree 2 morphism onto a minimal rational surface or onto $\mathbf F_1$, embedded in projective space by a very ample complete linear series. Among other things, we prove that any deformation of the canonical morphism of such surfaces $X$ is again a morphism of degree 2. A priori, this is not at all obvious, for the invariants $(p_g(X),c_1^2(X))$ of most of these surfaces lie on or above the Castelnuovo line; thus, in principle, a deformation of such $X$ could have a birational canonical map. We also map the region of the geography of surfaces of general type corresponding to the invariants of the surfaces $X$ and we compute the dimension of the irreducible moduli component containing $[X]$. In certain cases we exhibit some interesting moduli components parametrizing surfaces $S$ whose canonical map has different behavior but whose invariants are the same as the invariants of $X$. One of the interests of the article is that we prove the results about moduli spaces employing crucially techniques on deformation of morphisms. The key point or our arguments is the use of a criterion that requires only infinitesimal, cohomological information of the canonical morphism of $X$. As a by-product, we also prove the non-existence of "canonically" embedded multiple structures on minimal rational surfaces and on $\mathbf F_1$.
Reducción de operaciones en la solución de sistemas de ecuaciones lineales de gran escala aplicando Simulated Annealing
JORGE MARIO ARIAS P.,JULIAN DAVID GONZáLEZ H.,RAMóN ALFONSO GALLEGO R.
Scientia Et Technica , 2008,
Abstract: Este documento describe una novedosa técnica basada en un algoritmo metaheurístico denominado Simulated Annealing aplicado al ordenamiento de ecuaciones lineales en el proceso de solución, y con el cual, se busca reducir el aparecimiento de elementos de relleno que surgen en dicho proceso. Se describe en detalle la metodología aplicada y, para validarla, se pone a prueba en redes estándares IEEE de diferente complejidad.
Spectro-photometric close pairs in GOODS-S: major and minor companions of intermediate-mass galaxies
C. López-Sanjuan,M. Balcells,P. G. Pérez-González,G. Barro,J. Gallego,J. Zamorano
Physics , 2010, DOI: 10.1051/0004-6361/201014236
Abstract: (Abriged) Our goal here is to provide merger frequencies that encompass both major and minor mergers, derived from close pair statistics. We use B-band luminosity- and mass-limited samples from an Spitzer/IRAC-selected catalogue of GOODS-S. We present a new methodology for computing the number of close companions, Nc, when spectroscopic redshift information is partial. We select as close companions those galaxies separated by 6h^-1 kpc < rp < 21h^-1 kpc in the sky plane and with a difference Delta_v <= 500 km s^-1 in redshift space. We provide Nc for four different B-band-selected samples. Nc increases with luminosity, and its evolution with redshift is faster in more luminous samples. We provide Nc of M_star >= 10^10 M_Sun galaxies, finding that the number including minor companions (mass ratio >= 1/10) is roughly two times the number of major companions alone (mass ratio >= 1/3) in the range 0.2 <= z < 1.1. We compare the major merger rate derived by close pairs with the one computed by morphological criteria, finding that both approaches provide similar merger rates for field galaxies when the progenitor bias is taken into account. Finally, we estimate that the total (major+minor) merger rate is ~1.7 times the major merger rate. Only 30% to 50% of the M_star >= 10^10 M_Sun early-type (E/S0/Sa) galaxies that appear z=1 and z=0 may have undergone a major or a minor merger. Half of the red sequence growth since z=1 is therefore unrelated to mergers.
Prospectiva de las Didácticas Específicas, una rama de las Ciencias de la Educación para la eficacia en el aula.
Isidoro González Gallego
Perspectiva Educacional Formación de Profesores , 2010,
Abstract: Las Didácticas Específicas o Didácticas de área, son de reciente aparición en estos campos de conocimiento que constituyen “las Ciencias de la Educación”. Se trata de una especialización de las diferentes disciplinas científicas (la que se preocupa por los fenómenos generados al ser comunicadas), pero también de una especialización de las ciencias educativas, en tanto en cuanto se ocupa, dentro del análisis y la teorización curricular, de la aplicación de cada disciplina en el aula. Y ello, porque el horizonte final y la herramienta que la educación utiliza es, fundamentalmente, el conocimiento disciplinar: la "asignatura". Unas ciencias que estudien la utilización del conocimiento para educar tienen mucho que aportar y, pese a su reciente origen, lo están empezando a hacer a partir de la definición de sus objetivos y su marco de actuación, así como la creación de su propia comunidad científica.
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