Unbounded B-Fredholm operators on Hilbert spaces

This paper is concerned with the study of a class of closed linear operators densely defined on a Hilbert space H and called B-Fredholm operators. We characterize a B-Fredholm operator as the direct sum of a Fredholm closed operator and a bounded nilpotent operator. The notion of an index of a B-Fredholm operator is introduced and a characterization of B-Fredholm operators with index 0 is given in terms of the sum of a Drazin closed operator and a finite-rank operator. We analyse the properties of the powers Tm of a closed B-Fredholm operator and we establish a spectral mapping theorem

A linear optimization based method for data privacy in statistical tabular data

National Statistical Agencies routinely disseminate large amounts of data. Prior to dissemination these data have to be protected to avoid releasing confidential information. Controlled tabular adjustment (CTA) is one of the available methods for this purpose. CTA formulates an optimization problem that looks for the safe table which is closest to the original one. The standard CTA approach results in a mixed integer linear optimization (MILO) problem, which is very challenging for current technology. In this work we present a much less costly variant of CTA that formulates a multiobjective linear optimization (LO) problem, where binary variables are pre-fixed, and the resulting continuous problem is solved by lexicographic optimization. Extensive computational results are reported using both commercial (CPLEX and XPRESS) and open source (Clp) solvers, with either simplex or interior-point methods, on a set of real instances. Most instances were successfully solved with the LO-CTA variant in less than one hour, while many of them are computationally very expensive with the MILO-CTA formulation. The interior-point method outperformed simplex in this particular application.Peer ReviewedPreprin

Studies on reproduction of the mullet Mugil platanus Günther, 1880 (Actinopterygii, Mugilidae) from the Mar Chiquita coastal lagoon, Argentina: Similarities and differences with related species

The aim of the present study is to provide the first results on the reproductive biology of Mugil platanus, from the Mar Chiquita coastal lagoon (Argentina). To address this topic, we employed mainly female gonads, at both microscopic and macroscopic levels. The following stages of oocyte development were observed: (A) oogonias, (B) primary growth oocyte, (C) cortical alveolus stage, (D) yolked oocytes, and (E) atretic follicle. Also five of the seven stages of gonad maturity were macro and microscopically stated. The potential fecundity ranged between 1,002,026 and 2,548,769 yolked oocytes, with a mean of around 1,800,000 oocytes. The length at first maturity (L 50) was 450.6 total length (TL) and 367.7 standard length (SL) for females, 436.3 TL and 354.9 SL for males, showing a late sexual maturity for both sexes. Seasonal changes in gonadosomatic index (GSI) of females were observed. The mean GSI was ≤1 during six months of the year (January, June-October). Two modes in the ovarian maturation were observed, the most important in April-May and a secondary one in November-December. Both modes, correlated with the CPUE values, are indicative of the mullet migration from the coastal lagoon towards the sea for spawning. Differences and similarities have been found between Mugil platanus and other mugilid species (Mugil cephalus, Mugil curema, Liza aurata, Liza abu, Liza argentea, Myxus elongatus, and Valamugil cunnesius), from the reproductive point of view. The length at first maturity obtained for M. platanus is higher than in other mugilid species and when a relationship between maximum length and L 50 is established the percentage corresponding to Mugil platanus is 75%, while the others range between 50 and 61%.Fil: González Castro, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Marinas; Argentina. Universidad Autónoma Metropolitana-Iztapalapa; MéxicoFil: Macchi, Gustavo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Cousseau, María Berta. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Marinas; Argentin

Ideas de una investigación en curso. sobre la posibilidad de efectos político-artísticos a partir de la práctica del performance art.

El presente artículo introduce de manera general la investigación del autor sobre la posibilidad de la existencia de los efectos político-artísticos a partir de la práctica del performance art. Esta investigación está en desarrollo y es guiada principalmente, por la práctica del autor así como también por la de otros artistas y pensadores. El texto plantea el modo en que se aborda la práctica política y artística en la propuesta (como verbos y no sustantivos o adjetivos), para luego referir a la noción de efecto. posterior a ello, se presentan las características del performance art que permitirían vehicular los efectos político-artísticos, para proyectar una reflexión en torno a la concreción de estos efectos desde la figura del acontecimiento, terminando con una caracterización inicial de los mencionados efecto

La marxa nòrdica com a exercici físic que caldria prescriure a

El limfoedema és una complicació freqüent del tractament del càncer de mama. Està demostrat que l’exercici físic millora sensiblement la qualitat de vida d’aquestes pacients; tanmateix, l’adhesió als programes d’exercici físic és escassa. Cal un model sociosanitari assistencial que abordi aquest problema. Per la seva versatilitat, la marxa nòrdica es perfila com una activitat física ideal per ser utilitzada en aquest context

Mi tierra

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El Nordic Walking como ejercicio físico a prescribir en pacientes

El linfedema es una complicación frecuente del tratamiento para el cáncer de mama. Está demostrado que el ejercicio físico mejora sensiblemente la calidad de vida de estas pacientes, sin embargo la adhesión a los programas de ejercicio es escasa. Es necesario un modelo asistencial sociosanitario que aborde este problema. Gracias a su versatilidad, el Nordic Walking se perfila como una actividad física ideal para ser utilizada en este contexto

Análisis de la comunicación de “Chiara Ferragni” a través de las nuevas tecnologías y la creatividad

El siguiente trabajo de investigación pretende ser un acercamiento al conocimiento de las claves en la comunicación del caso “Chiara Ferragni”, editora del blog “The Blonde Salad”. Tras la investigación, se pretenden establecer las razones que han convertido a Chiara Ferragni, a través de su creatividad y el uso de las nuevas tecnologías, en una revolución mediática, abordando un estudio del caso basado en su modo de vida, trayectoria, estilo, personalidad, estrategias de comunicación e identidad corporativa.Grado en Publicidad y Relaciones Pública

On the convergence of semiiterative methods to the Drazin inverse solution of linear equations in Banach spaces

We consider general semiiterative methods (SIMs) to find approximate solutions of singular linear equations of the type x = Tx + c, where T is a bounded linear operator on a complex Banach space X such that its resolvent has a pole of order ν1 at the point 1. Necessary and sufficient conditions for the convergence of SIMs to a solution of x = Tx+ c, where c belongs to the subspace range R(I − T) ν1 ν1, are established. If c ∈ R(I − T) sufficient conditions for the convergence to the Drazin inverse solution are described. For the class of normal operators in a Hilbert space, we analyze the convergence to the minimal norm solution and to the least squares minimal norm solution. 1