Modulational instability windows in the nonlinear Schrödinger equation involving higher-order Kerr responses

We introduce a complete analytical and numerical study of the modulational instability process in a system governed by a canonical nonlinear Schrödinger equation involving local, arbitrary nonlinear responses to the applied field. In particular, our theory accounts for the recently proposed higher-order Kerr nonlinearities, providing very simple analytical criteria for the identification of multiple regimes of stability and instability of plane-wave solutions in such systems. Moreover, we discuss a new parametric regime in the higher-order Kerr response, which allows for the observation of several, alternating stability-instability windows defining a yet unexplored instability landscape.Xunta de Galicia | Ref. EM2013/00

Contribución al estudio de la ecología de las cigüeñas (Fam. Ciconiidae) en los llanos de Venezuela

Tesis Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, Departamento de Biología Animal I (Zoología), leída el 08-03-1993Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

O ESPAÇO PÚBLICO DA EDUCAÇÃO: imagens, narrativas e dilemas

O debate sobre a escola caracteriza-se, muitas vezes, por uma grande superficialidade. Ao longo deste texto assinala-se a complexidade dos problemas educacionais e tenta-se desfazer as ilusões de quem acredita em panaceias para a área. Em educação, os consensos são mais aparentes do que reais. É por isso que pareceu útil mostrar a ambiguidade de conceitos como “comunidades locais” ou “professor reflexivo”, que fazem sucesso nos tempos atuais. Assim, na primeira parte do texto, Imagens dos tempos que correm, descrevem-se as fragilidades do pensamento sobre a escola e as razões do insucesso das políticas educativas. Na segunda parte, O fim da educação, identificam-se algumas “narrativas” que organizam o debate sobre a escola, pondo em confronto a reconstrução da educação como espaço privado ou a sua renovação como espaço público. Finalmente, na terceira parte, Dilemas da profissão docente, retiram-se as consequências desta reflexão para o trabalho pedagógico, a partir de uma análise dos dilemas da comunidade, da autonomia e do conhecimento levando em consideração que a educação não se esgota no espaço-tempo da sala de aula, mas que se projeta em múltiplos lugares e ocasiões de formação.Palavras-chave: Dilemas da educação. Crise da educação. Espaço público da educação. Profissão docente.  THE PUBLIC SPACE OF EDUCATION: images, narratives and dilemmasAbstract The debate about school is often characterized by great superficiality. Throughout this text, the complexity of educational problems is highlighted, and an attempt is made to dispel the illusions of those who believe in panaceas for the area. In education, consensus is more apparent than real. That's why it seemed useful to show the ambiguity of concepts like “local communities” or “reflective teacher”, which are successful nowadays. Thus, in the first part of the text, Images of the current times, the fragilities of the school thought and the reasons for the failure of educational policies are described. In the second part, The end of education, some “narratives” that organize the debate about the school are identified, comparing the reconstruction of education as a private space or its renovation as a public space. Finally, in the third part, Dilemmas of the teaching profession, the consequences of this reflection for the pedagogical work are drawn from an analysis of the dilemmas of the community, autonomy and knowledge, taking into account that education is not limited to the classroom space- time, but it projects itself in multiple places and training occasions.Key-words: Education dilemmas. Crisis of education. Public space of education. Teaching profession. EL ESPACIO PÚBLICO DE LA EDUCACIÓN: imágenes, narrativas y dilemasResumenEl debate sobre la escuela se caracteriza, muchas veces, por una gran superficialidad. A lo largo de este texto se señala la complejidad de los problemas educacionales y se intenta deshacer las ilusiones de los que creen en panaceas para el área. En educación, los consensos son más aparentes que reales. Por eso, pareció útil mostrar la ambigüedad de conceptos como “comunidades locales” o “profesor reflexivo”, muy utilizados en los tiempos actuales. De esta manera, en la primera parte del texto, Imágenes de los tiempos que corren, se describen las fragilidades del pensamiento sobre la escuela y las razones de la falta de éxito de las políticas educativas. En la segunda parte, El fin de la educación, se identifican algunas “narrativas” que organizan el debate sobre la escuela, poniendo en enfrentamiento la reconstrucción de la educación como espacio privado o su renovación como espacio público. Finalmente, en la tercera parte, Dilemas de la profesión docente, se aprovechan las consecuencias de esta reflexión para el trabajo pedagógico, a partir de un análisis de los dilemas de la comunidad, de la autonomía y del conocimiento, llevando en cuenta que la educación no se agota en el espacio-tiempo del aula, sino que se proyecta en múltiples lugares y ocasiones de formación.Palabras clave: Dilemas de la educación. Crisis de la educación. Espacio público de la educación. Profesión docent

Modificaciones en los últimos escenarios sexuales, en los chicos

In the last decades, sexuality is one of the facets that raises more interest among evolutionary researchers. In this research the change occurred in the noncoital behavior that are analyzed in males, for a period of 10 years.  It took a very lengthy study, diachronic o transversal, with a trend over a sample of 2245 young university students (course 97-98) and 856 (course 07-08), in they were in their first and last year of their university course, in the University of Vigo. It was applied a structured survey, anonymous and voluntary, in which was the ages and variables were gathered, contemplating their noncoital behavior. The average age of university male, course 97-98, was of the ages 20-85 years old and the course 07-08, was of the ages 21-42 years old. The data was anaylzed using the statistical program SPSS 21.0.Analizamos  los cambios ocurridos en las últimas conductas coitales, en los hombres, durante un intervalo de 10 año, mediante un estudio longitudinal, diacrónico o transversal y de tendencia con una muestra de 2245 universitarios (curso 97-98) y 856 (07-08), que realizaban primero y último en la Universidad de Vigo. Se les aplicó una encuesta estructurada, anónima y voluntaria en la que se recogía la edad y variables sexuales, referidas a las últimas conductas coitales.  Los datos se analizan mediante el SPSS 21.0.  La edad media de las hombres universitarios, del curso 97-98, es de 20.85 años y la del curso 07-08, de 21.42 años. Las diferencias son significativa (p<.05) en cuanto a quienes iniciaron los coitos y edad, tiempo transcurrido desde el último coito, tipo de pareja sexual, satisfacción, por amor y deseo, el lugar donde aconteció, frecuencia coital, consumo etílico, uso de anticoncepción y elección de la misma

Variations of noncoital behavior of males

En esta investigación se analizan los cambios ocurridos en las últimas conductas no coitales, en los hombres, durante un intervalo de 10 años. Para ello se llevo a cabo un estudio longitudinal, diacrónico o transversal y de tendencia sobre una muestra de 2245 chicos universitarios (curso 97-98) y 856 (07-08), que realizaban el primer y último curso en la Universidad de Vigo. Se les aplicó una encuesta estructurada, anónima y voluntaria en la que se recogía la edad y variables sexuales, referidas a las conductas no coitales. La edad media de las hombres universitarios, del curso 97-98, es de 20.85 años y la del curso 07-08, de 21.42 años. Los datos se  analizaron mediante el programa estadístico SPSS 21.0.  Hay diferencias significativas (p<.05) entre ambos grupos en:  porcentaje de autoestimulación, frecuencia y edad de inicio, existencia de actividad sexual con otra persona, frecuencia de diferentes conductas sexuales no coitales y coitales y su edad de inicio.In the last decades, sexuality is one of the facets that raises more interest among evolutionary researchers. In this research the change occurred in the noncoital behavior that are analyzed in males, for a period of 10 years.  It took a very lengthy study, diachronic o transversal, with a trend over a sample of 2245 young university students (course 97-98) and 856 (course 07-08), in they were in their first and last year of their university course, in the University of Vigo. It was applied a structured survey, anonymous and voluntary, in which was the ages and variables were gathered, contemplating their noncoital behavior. The average age of university male, course 97-98, was of the ages 20-85 years old and the course 07-08, was of the ages 21-42 years old. The data was anaylzed using the statistical program SPSS 21.0

Corrosion resistance of a water-borne resin doped with graphene derivatives applied on galvanized steel

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGThe present work reports the effect of adding Graphene Oxide (GO) and reduced Graphene Oxide (rGO) in the corrosion protection provided by a water-borne resin applied on a galvanized steel substrate. Three concentrations, 0.05, 0.1 and 0.15 (all wt%) were tested. The results were markedly affected not only by the concentration of particles but also by their nature. Although the zeta potential values suggested good dispersibility of the particles in the resin, certain aggregation was observed, mainly in rGO 0.1 wt% and rGO 0.15 wt% formulations. The electrochemical impedance spectroscopy (EIS) technique characterised the free films' transport properties. The results suggested that the aggregation strongly influenced the film morphology. The rGO 0.1 wt% and rGO 0.15 wt% formulations exhibited percolating pores that facilitated the electrolyte uptake through the films. The EIS technique was also used to study the protective performance of the films when applied to the metallic substrate. The results confirmed the harmful effect of the particle's aggregation. The results were interesting for the rGO 0.05 wt% system, which displayed long-lasting protection properties. This performance was explained considering its good barrier properties and the zinc surface passivation by the generation of zincite, ZnO

Electrochemical characterization of a Fe-based shape memory alloy in an alkaline medium and the behaviour in aggressive conditions

A Fe-17Mn-6Si-19Cr-4Ni-1(V,C) shape memory steel (SMS) was characterised electrochemically in its unstrained and pre-strained conditions. The work focused on analysing the passive films generated in alkaline conditions, and on the behaviour of those passive samples in various Cl /OH ratios. The passive films were developed by cyclic voltammetry and their characterisation was performed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS); these tests were also carried out in 304 L stainless steel specimens for comparison purposes. The results indicated that the film characteristics (thickness and composition) were similar in all the samples, although higher corrosion resistance was observed in the 304 L due to the higher Cr content. In addition, the behaviour of the passive samples in aggressive conditions was assessed by potentiodynamic measurements. The results stated that the shape memory steels were more sensitive than the stainless steel to the aggressive conditions, especially when the alloy was pre-strained. It was also observed that the SMS exhibited a characteristic corrosion morphology localized at the grain boundariesAgencia Estatal de Investigación | Ref. TED2021-130605B-I00Financiado para publicación en acceso aberto: Universidade de Vigo/CISU

Marginal changes at bone-level implants supporting fixed screw-retained partial implant prostheses with or without intermediate standardised abutments: 1-year results of a randomised controlled clinical trial

Objective: To compare marginal changes at bone- level implants restored with screw- retained implant prosthesis with or without intermediate standardised abutments, after 1 year of follow-up.Materials and Methods: Thirty- six partially edentulous patients received 72 implants. Each patient received 2 implants and a 2- to 4- unit screw- retained implant- prosthesis. The test group received implants consisting of a screw- retained prosthesis connected directly to the implant shoulder, while the prostheses in the control group were con-nected through a 3- mm standardised intermediate abutment. Clinical and radiological data were recorded at baseline and at 3, 6 and 12 months in follow-up visits.Results: At 12 months, the marginal bone loss was 0.17 ± 0.24 mm for the test group (19 patients) and 0.09 ± 0.15 mm for the control group (17 patients), with no statistically significant differences (p> .05). The mean probing pocket depth was 2.96 mm ± 0.46 for the test group and 2.86 ± 0.62 mm for the control group. The test and control groups showed bleeding on probing levels of 18.86 ± 14.12% and 13.73 ± 17.66%, re-spectively. All patients scored below 25% on the plaque index levels.Conclusions: Restoration of bone- level implants with fixed screw- retained partial prostheses with or without intermediate abutments presented similar radiographic and clinical outcomes after 1 yearS