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A simple method for fabricating phase-shifted fibre Bragg gratings with flexible choice of centre wavelength

A simple technique for fabricating phase-shifted fibre Bragg gratings (PSFBGs) without the use of a phase-shifted phase mask is presented. Two, 3-mm long, standard fibre Bragg gratings (FBGs) were inscribed sequentially in singlemode fibre at the same Bragg wavelength such that the FBGs physically overlapped by one grating period. This induces a spectral-hole in the middle of the reflection spectrum of a standard FBG, equivalent to a π-phase shifted FBG. The flexibility of the technique in writing PSFBGs at any choice of wavelength is demonstrated. The results show that PSFBG devices produced by this method are highly reproducible and the process is fas

Institución literaria y práctica discursiva

El estudio de las relaciones existentes entre Literatura e Historia, cuya existencia postulamos todos, constituye un campo de reflexión sumamente amplio y complejo. Por esta razón, en vez de tratar un aspecto determinado de la cuestión, quisiera puntualizar una serie de elementos teóricos bajo la forma de interrogaciones, sugerencias o esclarecimientos desde las posiciones de la sociocrítica.The study of the relationships between literature and history, whose existence all we affirm, is a field of reflection extremely broad and complex. For this reason, instead of dealing with a specific aspect of the issue, I would like to point out a series of theoretical elements in the form of questions, suggestions or clarifications from the positions of the sociocritical

La técnica fisioterapéutica de Françoise Mézières: una solución efectiva para la corrección de las problemáticas posturales y respiratorias de los instrumentistas de viento

En este artículo se exponen algunas de las problemáticas más habituales que presentan los instrumentistas de viento durante su estudio, relacionadas con el uso del cuerpo y la respiración, las cuales les impiden llevar a cabo el proceso de aprendizaje del instrumento de una manera confortable y, al mismo tiempo, no les permiten expresar todo su potencial musical. Para dar una solución a dichas problemáticas se comentan las posibilidades y las prestaciones que ofrece la técnica fisioterapéutica de Françoise Mézières, tanto para poder modificar la situación expuesta en el caso de los estudiantes de instrumentos de viento, como para ser consideradas por los profesionales de los mismos. Se trata de una técnica que presenta una concepción novedosa dentro de la fisioterapia, que por el hecho de tener una visión holística del funcionamiento del cuerpo, permite reequilibrarlo y devolverlo a su estado natural, pudiendo entonces llevarse a cabo la práctica del instrumento de viento de la manera más apropiada posible y más confortable para el individuo.This article discusses some of the most common problems presented by wind instruments during their study, related to body use and breathing, which prevent them from carrying out the process of learning the instrument in a comfortable way and, at the same time, do not allow them to express their full musical potential. In order to solve these problems, the possibilities and benefits offered by the physiotherapeutic technique of Françoise Mézières are discussed, not only to modify the situation exposed in the case of wind instruments students, but also for the professionals of the same. It is a technique that presents a novel conception within physiotherapy, which by having a holistic view of the functioning of the body, allows to rebalance it and return it to its natural state, being able to then carry out the practice of the wind instrument of the most appropriate and comfortable way for the individual

A closed-loop digitally controlled MEMS gyroscope with unconstrained Sigma-Delta force-feedback

In this paper, we describe the system architecture and prototype measurements of a MEMS gyroscope system with a resolution of 0.025 degrees/s/root Hz. The architecture makes extensive use of control loops, which are mostly in the digital domain. For the primary mode both the amplitude and the resonance frequency are tracked and controlled. The secondary mode readout is based on unconstrained Sigma Delta force-feedback, which does not require a compensation filter in the loop and thus allows more beneficial quantization noise shaping than prior designs of the same order. Due to the force-feedback, the gyroscope has ample dynamic range to correct the quadrature error in the digital domain. The largely digital setup also gives a lot of flexibility in characterization and testing, where system identification techniques have been used to characterize the sensors. This way, a parasitic direct electrical coupling between actuation and readout of the mass-spring systems was estimated and corrected in the digital domain. Special care is also given to the capacitive readout circuit, which operates in continuous time