Application of fractional delay filters to tune the centre frequency location of single-band sigma-delta modulators

This paper presents a novel technique for the design of narrow-band sigma-delta modulators with an embedded tunable centre frequency mechanism. This method demonstrates that the use of sum filters combined with a fractional delayer provide the flexibility of tuning the noise shaping band for any desired variable centre frequency input signal.

A comparative study of complex multiple-band noise-shaping sigma-delta modulators for multi-tone input signals

This paper presents a comparative study of complex single-bit and multi-bit sigma-delta modulators that are capable of providing concurrent multiple-band noise-shaping for multi-tone narrow-band input signals. The concepts applied for the three design methodologies are based on the noise transfer functions of complex comb, complex slink and complex multi-notch filters.

Nuevos juegos en el parque.

Proyecto de acondicionamiento del espacio exterior que se centra en la remodelación de nuevas estructuras que faciliten y mejoren la explotación de las posibilidades que ofrece el parque del centro. Los objetivos son: conocer y cuidar el entorno y la naturaleza; manipular y experimentar con los materiales que ésta nos brinda; fomentar la creatividad; favorecer la psicomotricidad; desarrollar procesos de autonomía y cooperación; y observar y disfrutar de los espacios libres. Las propuestas que se plantean para la consecución de estos objetivos son múltiples y variadas, aunque debido a la escasez de recursos económicos solo se llevan a la práctica la construcción de un círculo de tubos de hormigón y una plataforma de cemento para colocar la piscina en verano y para realizar juegos de colores cuando ésta no esté. La valoración del proyecto se basa en la observación de los juegos con las nuevas construcciones. De esta forma, se señala el aumento en la variedad de los mismos y la mejora en la creatividad y psicomotricidad.

Una lección magistral para descubrir y respetar la naturaleza.

Comentario sobre la granja escuela Virgen de las Cruces de Daimiel (Ciudad Real). Mediante actividades agropecuarias destinadas a alumnos de Educación Infantil, Primaria y Secundaria se promueve una educación asentada en el respeto al medio ambiente. Se realizan cuatro talleres: vamos a la granja, el huerto e invernadero, transformación de alimentos y taller de ganadería.

A Pollen Chase Experiment; Examining Varying Levels of Embryonic Inbreeding Depression

A pollen chase experiment was performed upon three Costa Rican populations of Witheringia solanacea to examine the breakdown of genetically enforced self incompatibility (SI) and the extent of embryonic inbreeding depression. Self-pollen was applied in the bud, with outcross pollen applied one day later, and outcross pollinations at both intervals as a control. A variety of responses were found among the populations. BOHS readily accepted self pollen and suffered from very low inbreeding depression. Monteverde and Las Cruces both have lower fruit set with self-pollination precedence indicating that bud pollinations can overcome the self-incompatibility response and that embryonic death due to inbreeding depression causes fruit failure. The treatment:control fruit set is higher for the Las Cruces plants indicating stronger SI response Self-precedence seeds from the Las Cruces plants are likely to be outcrossed. Self-precedence seeds from Monteverde are likely selfed.

El significado aritmológico de la Tríada y sus Proyecciones Filosófico-Religiosas

Bertrand Russell dio una solución lógica general a la definición de los números caracterizando al número tres como la clase que es correspondiente a todas las clases biunívocas con los grupos de tres. Para Frege la definición del número era una de las cruces de la comprensión de la aritmética. Hegel, por su parte, bajo el impulso de la triplicidad kantiana de los juicios sintéticos, teoréticos y prácticos y la influencia de la concepción trinitaria cristiana advertía que la contraposición de los opuestos al no ser contradictoria permitía el desarrollo deviniente. La aritmología pitagórica sobre los números naturales destacó la definición del tres caracterizada por su naturaleza de mediedad. Retomando estas bases de pura inteligibilidad y las especulaciones gnósticas sobre la tríada mostraremos sus proyecciones filosófico-religiosas.

Results from experiments and investigations on the kelp crab Taliepus dentatus

Studies of thermal tolerance in marine ectotherms are key in understanding climate effects on ecosystems; however, tolerance of their larval stages has rarely been analyzed. Larval stages are expected to be particularly sensitive. Thermal stress may affect their potential for dispersal and zoogeographical distribution. A mismatch between oxygen demand and the limited capacity of oxygen supply to tissues has been hypothesized to be the first mechanism restricting survival at thermal extremes. Therefore, thermal tolerance of stage zoea I larvae was examined in two populations of the Chilean kelp crab Taliepus dentatus, which are separated by latitude and the thermal regime. We measured temperature-dependent activity, oxygen consumption, cardiac performance, body mass and the carbon (C) and nitrogen (N) composition in order to: (1) examine thermal effects from organismal to cellular levels, and (2) compare the thermal tolerance of larvae from two environmental temperature regimes. We found that larval performance is affected at thermal extremes indicated by decreases in activity, mainly in maxilliped beat rates, followed by decreases in oxygen consumption rates. Cardiac stroke volume was almost temperature-independent. Through changes in heart rate, cardiac output supported oxygen demand within the thermal window whereas at low and high temperature extremes heart rate declined. The comparison between southern and central populations suggests the adaptation of southern larvae to a colder temperature regime, with higher cardiac outputs due to increased cardiac stroke volumes, larger body sizes but similar body composition as indicated by similar C:N ratios. This limited but clear differentiation of thermal windows between populations allows the species to widen its biogeographical range.