Isoperimetric inequalities in Riemann surfaces of infinite type

75 pages, 1 figure.-- MSC2000 code: 30F45.MR#: MR1715412 (2000j:30075)Zbl#: Zbl 0935.30028Research partially supported by a grant from Dirección General de Enseñanza Superior (Ministerio de Educación y Ciencia), Spain.Publicad

Approximation theory for weighted Sobolev spaces on curves

17 pages, no figures.-- MSC2000 codes: 41A10, 46E35, 46G10.MR#: MR1882649 (2003c:42002)In this paper we present a definition of weighted Sobolev spaces on curves and find general conditions under which the spaces are complete. We also prove the density of the polynomials in these spaces for non-closed compact curves and, finally, we find conditions under which the multiplication operator is bounded on the completion of polynomials. These results have applications to the study of zeroes and asymptotics of Sobolev orthogonal polynomials.Research of V. Álvarez, D. Pestana and J.M. Rodríguez partially supported by a grant from DGI, BFM2000-0206-C04-01, Spain.Publicad

Generalized weighted Sobolev spaces and applications to Sobolev orthogonal polynomials, I

36 pages, no figures.-- MSC2000 codes: 41A10, 46E35, 46G10.-- Part II of this paper published in: Approx. Theory Appl. 18(2): 1-32 (2002), available at: http://e-archivo.uc3m.es/handle/10016/6483MR#: MR2047389 (2005k:42062)Zbl#: Zbl 1081.42024In this paper we present a definition of Sobolev spaces with respect to general measures, prove some useful technical results, some of them generalizations of classical results with Lebesgue measure and find general conditions under which these spaces are complete. These results have important consequences in approximation theory. We also find conditions under which the evaluation operator is bounded.Research by first (J.M.R.), third (E.R.) and fourth (D.P.) authors was partially supported by a grant from DGI (BFM 2000-0206-C04-01), Spain.Publicad

Optimal streaks in a Falkner-Skan boundary layer

This paper deals with the optimal streaky perturbations (which maximize the perturbed energy growth) in a wedge flow boundary layer. These three dimensional perturbations are governed by a system of linearized boundary layer equations around the Falkner-Skan base flow. Based on an asymptotic analysis of this system near the free stream and the leading edge singularity, we show that for acute wedge semi-angle, all solutions converge after a streamwise transient to a single streamwise-growing solution of the linearized equations, whose initial condition near the leading edge is given by an eigenvalue problem first formulated in this context by Tumin (2001). Such a solution may be regarded as a streamwise evolving most unstable streaky mode, in analogy with the usual eigenmodes in strictly parallel flows, and shows an approximate self-similarity, which was partially known and is completed in this paper. An important consequence of this result is that the optimization procedure based on the adjoint equations heretofore used to define optimal streaks is not necessary. Instead, a simple low-dimensional optimization process is proposed and used to obtain optimal streaks. Comparison with previous results by Tumin and Ashpis (2003) shows an excellent agreement. The unstable streaky mode exhibits transient growth if the wedge semi-angle is smaller than a critical value that is slightly larger than $\pi/6$, and decays otherwise. Thus the cases of right and obtuse wedge semi-angles exhibit less practical interest, but they show a qualitatively different behavior, which is briefly described to complete the analysis

Weighted Sobolev spaces on curves

45 pages, no figures.-- MSC1987 codes: 41A10, 46E35, 46G10.MR#: MR1934626 (2003j:46038)Zbl#: Zbl 1019.46026In this paper we present a definition of weighted Sobolev spaces on curves and find general conditions under which the spaces are complete for non-closed compact curves. We also prove the density of the polynomials in these spaces and, finally, we find conditions under which the multiplication operator is bounded in the space of polynomials.Research of second (D.P.), third (J.M.R.) and fourth (E.R.) authors was partially supported by a grant from DGI (BFM 2000-0206-C04-01), Spain.Publicad

Generalized weighted Sobolev spaces and applications to Sobolev orthogonal polynomials, II

32 pages, no figures.-- MSC1987 codes: 41A10, 46E35, 46G10.-- Part I of this paper published in: Acta Appl. Math. 80(3): 273-308 (2004), available at: http://e-archivo.uc3m.es/handle/10016/6482MR#: MR1928169 (2003h:42034)Zbl#: Zbl 1095.42014^aWe present a definition of general Sobolev spaces with respect to arbitrary measures, $W^{k,p}(\Omega,\mu)$ for $1\leq p\leq\infty$. In Part I [Acta Appl. Math. 80(3): 273-308 (2004), http://e-archivo.uc3m.es/handle/10016/6482] we proved that these spaces are complete under very mild conditions. Now we prove that if we consider certain general types of measures, then $C^\infty_c({\bf R})$ is dense in these spaces. As an application to Sobolev orthogonal polynomials, we study the boundedness of the multiplication operator. This gives an estimation of the zeroes of Sobolev orthogonal polynomials.Research partially supported by a grant from DGES (MEC), Spain.Publicad

Estrategias de vacunación en Atención Primaria

Las actividades de inmunización no son exclusivas de la infancia, sino que deben proseguirse a lo largo de toda la vida, con un calendario vacunal que contemple las diferentes características de cada individuo (edad, condiciones laborales, viajes, enfermedades concomitantes, etc. ). La vacunación es, ante todo, una medida sanitaria de actuación sobre la comunidad que busca la protección o inmunidad colectiva o de grupo, a través de la cual, se ha conseguido una importante reducción de la incidencia y de la mortalidad asociadas a determinadas enfermedades inmunoprevenibles con relación a la era prevacunal. El efecto final (efectividad) de un programa de vacunaciones está condicionado tanto por la propia eficacia de la vacuna como por la cobertura vacunal (porcentaje de la población diana correctamente vacunada). La atención primaria constituye un contexto único para aplicar estrategias que favorezcan los objetivos del programa de vacunaciones. La progresiva informatización de los centros de salud permite utilizar metodología innovadora como los programas facilitados por los Centers of Disease Control de Atlanta (CDC) para el asesoramiento clínico de inmunización. http://www.cdc.gov/nip/casa/Default.htm que, acompañado de otras medidas, logran incrementar y mantener en el tiempo las coberturas vacunales. Los tres pilares de información sobre los que se sustentan los programas de vacunación son: La vigilancia epidemiológica de las enfermedades sujetas a control (enfermedades de declaración obligatoria, sistemas de información microbiológica, conjunto mínimo básico de datos de alta hospitalaria, etc.), Conocimiento de las coberturas vacunales, Estudios de seroprevalencia. Junto a estrategias generales de inmunización existen estrategias específicas dirigidas a grupos de riesgo. Estos suelen caracterizarse por bajas coberturas vacunales y donde suelen encontrarse los grupos a los que hay que dirigirse de forma específica, a veces relacionadas con falta de información sobre vacunaciones: viajeros, inmigrantes, poblaciones marginales, profesiones de riesgo, discapacitados, enfermos (inmunodeprimidos , enfermedades metabólicas, cardiópatas,...) y sujetos con condiciones de riesgo (drogadicción, promiscuidad sexual,...) En cualquier intervención en materia de vacunaciones, se hace imprescindible la coordinación entre los diferentes profesionales del equipo de Atención Primaria: médicos de familia, pediatras, enfermeros/as y trabajadores sociales.Una adecuada estructura del programa, junto a una correcta práctica profesional, son los apoyos básicos para la consecución de las metas de todo programa de vacunaciones: elevadas coberturas inmunitarias -merced a la consecución de altas coberturas vacunales- y reducción de la morbimortalidad por enfermedades inmunoprevenibles. En resumen, las líneas de avance inmediato han de aprovechar las oportunidades que ofrecen la gestión en atención primaria, las tecnologías de la información y la comunicación y la implicación de los ciudadanos en el diseño de futuros calendarios vacunales pediátricos y del adulto. Estas estrategias seguramente incrementarán las coberturas vacunales de la población que actualmente está menos inmunizada

Annotation scheme for citation classification in scientific literature

El análisis de citas bibliográficas que usa variaciones de métodos de conteo provoca deformaciones en la evaluación del impacto. Para enriquecer el cálculo de los factores de impacto se necesita entender el tipo de influencia de los aportes de un investigador sobre el autor que los menciona. Para ello, se requiere realizar análisis de contenido del contexto de las citas que permita obtener su función, polaridad e influencia. El presente artículo trata sobre la definición de un esquema de anotación tendiente a la creación de un corpus de acceso público que sea la base de trabajo colaborativo en este campo, con miras al desarrollo de sistemas que permitan llevar adelante tareas de análisis de contenido con el objetivo planteado.Citation analysis that uses counting methods causes deformations in impact factor assessment. To enrich impact factor calculation is necessary to understand the kind of influence that the contributions of an author have over another´s work. For this purpose, it is required to perform citation content analysis to obtain its function, polarity and influence in a context within an article that mentioned it. In this paper, we focus in the definition of an annotation scheme aimed at creating a public access corpus that be the basis of collaborative work in this field, in order to develop citation content analysis to obtain criteria for impact evaluation

Using classifiers to predict linear feedback shift registers

Proceeding of: IEEE 35th International Carnahan Conference on Security Technology. October 16-19, 2001, LondonPreviously (J.C. Hernandez et al., 2000), some new ideas that justify the use of artificial intelligence techniques in cryptanalysis are presented. The main objective of that paper was to show that the theoretical next bit prediction problem can be transformed into a classification problem, and this classification problem could be solved with the aid of some AI algorithms. In particular, they showed how a well-known classifier called c4.5 could predict the next bit generated by a linear feedback shift register (LFSR, a widely used model of pseudorandom number generator) very efficiently and, most importantly, without any previous knowledge over the model used. The authors look for other classifiers, apart from c4.5, that could be useful in the prediction of LFSRs. We conclude that the selection of c4.5 by Hernandez et al. was adequate, because it shows the best accuracy of all the classifiers tested. However, we have found other classifiers that produce interesting results, and we suggest that these algorithms must be taken into account in the future when trying to predict more complex LFSR-based models. Finally, we show some other properties that make the c4.5 algorithm the best choice for this particular cryptanalytic problem.Publicad