5,919 research outputs found

    Harmonic mappings and conformal minimal immersions of Riemann surfaces into RN

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    We prove that for any open Riemann surface N, natural number N ≥ 3, non-constant harmonic map h:N→R N−2 and holomorphic 2-form H on N , there exists a weakly complete harmonic map X=(Xj)j=1,…,\scN:N→R\scN with Hopf differential H and (Xj)j=3,…,\scN=h. In particular, there exists a complete conformal minimal immersion Y=(Yj)j=1,…,\scN:N→R\scN such that (Yj)j=3,…,\scN=h . As some consequences of these results (1) there exist complete full non-decomposable minimal surfaces with arbitrary conformal structure and whose generalized Gauss map is non-degenerate and fails to intersect N hyperplanes of CP\scN−1 in general position. (2) There exist complete non-proper embedded minimal surfaces in R\scN, ∀\scN>3.Ministerio de Ciencia y Tecnología MTM2007-61775Ministerio de Ciencia y Tecnología MTM2007-64504Junta de Andalucía P09-FQM-508

    Complete minimal surfaces and harmonic functions

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    We prove that for any open Riemann surface N and any non constant harmonic function h : N → R, there exists a complete conformal minimal immersion X : N → R3 whose third coordinate function coincides with h. As a consequence, completeminimal surfaceswith arbitrary conformal structure andwhose Gauss map misses two points are constructed.Ministerio de Educación y Ciencia MTM2007-61775Ministerio de Educación y Ciencia MTM2007-64504Junta de Andalucía P06-FQM-01642

    A decomposition procedure based on approximate newton directions

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    The efficient solution of large-scale linear and nonlinear optimization problems may require exploiting any special structure in them in an efficient manner. We describe and analyze some cases in which this special structure can be used with very little cost to obtain search directions from decomposed subproblems. We also study how to correct these directions using (decomposable) preconditioned conjugate gradient methods to ensure local convergence in all cases. The choice of appropriate preconditioners results in a natural manner from the structure in the problem. Finally, we conduct computational experiments to compare the resulting procedures with direct methods, as well as to study the impact of different preconditioner choices

    Burnout, Resilience and Self-Esteem in School Teaching University Students

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    Burnout syndrome seems to involve fatigue that is characterised by loss of motivation, lack of energy, and some apathy as a consequence of continued exposure to stress in demanding performance circumstances. Background: The goal of the present study is to analyse the relationship between burnout in university students with a degree in Teaching and some variables that may be associated with it such as self-esteem, resilience or age. Methods: A total of 1547 graduate students enrolled in the career of Teaching in the Faculty of Educational Sciences of the University of Granada, Spain, participated in the study. Of them, 337 (21.8%) were men, 1195 (77.3%) were women, 14 (0.9%) indicated other gender options, and 1 (0%) did not respond to this item. The mean age of the participants was 20.52. Results: The results show that low levels of self-esteem and resilience, are the variables that best predict the increase in burnout in students of Teaching. Conclusions: Findings are discussed regarding applied implications and the need for future research. Intervention initiatives focused on enhancing personal strengths such as resilience or self-esteem can help students to cope with the stress associated with demanding educational situations and thus reduce the presence of burnout

    Presencia y edad de vulcaniras en el Jurásico del Norte de Valencia (Cordillera Ibérica, España)

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    Se da cuenta en este trabajo de la presencia de rocas volcánicas, intercaladas en las series carbonatadas del Jurásico del norte de la provincia de Valencia (región de Alcublas), cuya edad ha podido ser determinada como Bajociense inferior. El hecho de que exista vulcanismo de edad similar en gran parte de las codilleras Béticas(subbético), sugiere la existencia de una fase de distensión con marcada amplitud durante los primeros tiempos del Jurásico medio. Por otra parte, las posibles emanaciones de sílice, acompañadas del proceso volcánico, pudieron ser unas de las causantes principales de la presencia ide nódulos de sílex en el Bajociense de una amplia región.Peer reviewe
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