Construcción de un amplificador en clase D y evaluación de sus prestaciones

Este trabajo de fin de grado aborda el diseño y la construcción de una etapa de salida clase D. El circuito diseñado, con una estructura relativamente sencilla, se puede utilizar para analizar los diferentes bloques que lo integran en prácticas de laboratorio. Se ha usado el circuito integrado TL494 para la generación de la señal PWM a una frecuencia en torno a los 250 kHz. Los pulsos de la señal PWM se aplican al circuito integrado IR2110, que es capaz de activar los transistores de salida (MOSFET de canal n) de la forma más segura, rápida y eficiente posible. Para evitar la posibilidad de que lleguen a conducir simultáneamente (lo que provocaría el cortocircuito entre los buses de continua) el circuito introduce un tiempo de retardo (lo que se conoce como dead time o tiempo muerto). Se ha usado un filtro LC pasa bajas con respuesta de tipo Butterworth para reconstruir la señal y reproducirla adecuadamente en la carga.This Undergraduate Thesis addresses the design and building of a Class D output stage. The designed circuit, with a relatively simple structure, can be used to analyze its different building blocks in laboratory experiments. The TL494 integrated circuit has been used for the generation of the PWM signal at a frequency around 250 kHz. PWM pulses are applied to the IR2110 integrated circuit, which is capable of driving output transistors (n-channel MOSFETs) as safely, quickly and efficiently as possible. To avoid the possibility of simultaneous driving (which would cause the short circuit between DC buses) the circuit introduces a delay time (known as dead time) A low pass LC filter with Butterworth response is used to reconstruct the signal and reproduce it properly in the load

On the functional regression model and its finite-dimensional approximations

The problem of linearly predicting a scalar response Y from a functional (random) explanatory variable X=X(t),t∈I is considered. It is argued that the term “linearly” can be interpreted in several meaningful ways. Thus, one could interpret that (up to a random noise) Y could be expressed as a linear combination of a finite family of marginals X(ti) of the process X, or a limit of a sequence of such linear combinations. This simple point of view (which has some precedents in the literature) leads to a formulation of the linear model in terms of the RKHS space generated by the covariance function of the process X(t). It turns out that such RKHS-based formulation includes the standard functional linear model, based on the inner product in the space L2[0,1], as a particular case. It includes as well all models in which Y is assumed to be (up to an additive noise) a linear combination of a finite number of linear projections of X. Some consistency results are proved which, in particular, lead to an asymptotic approximation of the predictions derived from the general (functional) linear model in terms of finite-dimensional models based on a finite family of marginals X(ti), for an increasing grid of points tj in I. We also include a discussion on the crucial notion of coefficient of determination (aimed at assessing the fit of the model) in this setting. A few experimental results are givenPID2019-109387GB-I0

Lizard thermoregulation revisited after two decades of global warming

CRUE-CSIC (Acuerdos Transformativos 2022)1.Although the effects of global warming on thermoregulation are usually explored using predictions of climate envelop modelling, such effects should best be analysed empirically, studying the same population with the same methods after a long enough period of temperature rise. 2. We used a 30-year long database about body temperatures (Tbs) of field-active Psammodromus algirus lizards inhabiting a well-conserved temperate open forest, and we focused on the summers of 1997 and 2017 to compare Tbs, environmental operative temperatures (Tes), their proximity to the selected thermal range (Tsel), and the selection of sunlit and shaded patches all along the day. From these data, we estimated the precision (standard deviation of Tbs), accuracy (average distance between Tbs and Tsel) and effectiveness (extent to which Tbs are closer to Tsel than Tes) of thermoregulation. 3. Of the highest 5% of all Tbs in the database, 95% were recorded in 2017, when the adjustment to Tsel was much better for Tbs selected in a laboratory thermogradient than for field Tbs (percentages of Tbs above Tsel of 2% and 52% respectively). 4. In 2017, especially after 12:00 h, the selection of shaded patches (87% of lizards in full shade vs. <1% in full sun) was more intense than in 1997, contributed more to overall thermoregulation, and produced a larger difference between Tes and Tbs. In spite of this, Tbs were lower—and closer to Tsel—in 1997 (when most shaded patches offered favourable thermal opportunities, with Tes within or below Tsel) than in 2017 (when only 33% of full shade Tes, and 8% of all Tes, were within or below Tsel). As a consequence, estimates of the accuracy and effectiveness of thermoregulation decreased over the 20-year period examined. 5. We conclude that given the low availability of Tes within or below Tsel, lizards cannot longer prevent the rise of their Tbs above Tsel, at least in hot summer days. Thus, the effects of global warming are already hindering the ability of lizards to buffer environmental change by behavioural means, even in temperate forests with a fine-grained mosaic of sun and shade patches.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEMinisterio de Ciencia e Innovación (MICINN)pu

Outcomes of cochlear implantation in pediatric age. Retrospective study in 72 patients.

Introduction and objective: Severe to profound grades of the prelocutive auditory deficiency (AD) are considered a disability with significant consequences on intellectual development of children. In this context, early diagnostics and treatment arise as an effective solution. Method: Retrospective, longitudinal analysis of 72 implanted patients, younger than 14 years, and comparison of audiometric parameters before and after surgery, and analysis of verbal development at 2 years after intervention. Results: Post-surgical follow-up showed an audiometric gain at 2 years of 62,79 dB (SD=14,86 dB) (p&lt;0,05); greater results to those obtained with the use of hearing aid. Audiometric improvement had no a statistically significant relationship with the child´s age, unlike with the kind of cochlear implant (CI). Verbal development of the child is inversely proportional to the lower the age of implant (p&lt;0,05). Discussion: Different societies and studies placed to CI as the most effective treatment of the severe-profound AD, supporting the outcomes of our analysis, as so as occurring with those which show that verbal development is greater with earlier implantation. Conclusions: CI gets greater auditory outcomes that hearing aid, improving the prognostic of severe-profound AD. The age is essential in verbal development (inversely proportional relationship), but not in auditory gain. Analysis of verbal development according to the kind of CI showed a favorable distribution to simultaneous bilateral CIs (p&gt;0,05).Introducción y objetivo: Los grados profundo y severo de la deficiencia auditiva (DA) prelocutiva se consideran una discapacidad con importantes consecuencias en el desarrollo intelectual de los niños. En este escenario, el diagnóstico precoz y la atención temprana surgen como una solución efectiva. Método: Estudio retrospectivo longitudinal de 72 pacientes, implantados por debajo de los 14 años, y comparación de parámetros audiométricos antes y después de la cirugía, y estudio del desarrollo verbal tras 2 años post-intervención. Resultados: Se objetivó una ganancia audiométrica a los 2 años de la intervención de 62,79 dB (DE=14,86 dB) (p&lt;0,05); resultados muy superiores a los obtenidos con el uso de audífonos. La mejora audiométrica no tuvo relación estadísticamente significativa con la edad del niño, pero sí con el tipo de implante. El desarrollo verbal del niño es mayor cuanto menor sea la edad de implantación (p&lt;0,05). Discusión: Diversas sociedades y estudios colocan a los implantes cocleares (IC) como el tratamiento más eficaz de la DA severa-profunda y sus comorbilidades, avalando los resultados de nuestro estudio, al igual que ocurre con los estudios que demuestran que el desarrollo verbal es mejor si la implantación es temprana. Conclusiones: El IC obtiene unos resultados auditivos mejores que la estimulación audioprotésica, mejorando el pronóstico de la DA severa y profunda. La edad es fundamental en el desarrollo verbal (relación inversamente proporcional), no así en la ganancia auditiva. El análisis del desarrollo verbal según el tipo de implante mostró una distribución favorable a los IC bilaterales simultáneos (p&gt;0,05)./n

¿Temperaturas al sol y a la sombra? ¿Cómo se mide la temperatura en una estación meteorológica?

La medición de temperatura no es algo tan sencillo como pudiera parecer en un principio. En este artículo realizaremos algunas aclaraciones sobre este asunto y sobre qué y cómo se mide la temperatura del aire en las estaciones meteorológicas

Inter- and intra-microcycle external load analysis in female professional soccer players: A playing position approach

[EN] This study analyzes the inter- and intra-differences in external load across the microcycle in professional female soccer players. External load during four consecutive microcycles (i.e., M1, M2, M3, and M4) and training sessions (i.e., MD-4, MD-3, MD-2, and MD-1) and a match day (i.e., MD) were registered in seventeen female professional soccer players (age: 26.3 ± 4.6 years; height: 166.3 ± 6.1 cm; body mass: 59.8 ± 6.8 kg; and body mass index: 21.6 ± 1.7 kg m-2) who belonged to the same team in Spanish first division. A 10-Hz GPS that integrated a 100-Hz triaxial accelerometer was used to register external load. The results showed lower decelerations in M2 compared to M1 and M3 (p < 0.05), lower highintensity distance (>16.0 km h-1) in M3 vs. M2, and greater relative sprint distance (>21.0 km min-1) in M4 vs. M1 and M3 (p < 0.05). MD-3 registered the highest load for all variables (p < 0.05). Forwards (FWs) performed (p < 0.05) significantly more sprints (meters and number > 21.0 km h-1) than central midfielders (CMs) and central defenders (CDs) in MD-2 and MD. Both, fitness and conditioning staff should pay special attention to the external loads for each playing position in training sessions to optimize the training process.S

LA RELACIÓN ESCUELA – FAMILIA PARA APRENDER A CONVIVIR. UN DESAFÍO LATENTE

escuela, familia, convivi

The combined use of raw and phylogenetically independent methods of outlier detection uncovers genome‐wide dynamics of local adaptation in a lizard

Local adaptation is a dynamic process by which different allele combinations are se-lected in different populations at different times, and whose genetic signature can be inferred by genome-wide outlier analyses. We combined gene flow estimates with two methods of outlier detection, one of them independent of population coances-try (CIOA) and the other one not (ROA), to identify genetic variants favored when ecology promotes phenotypic convergence. We analyzed genotyping-by-sequencing data from five populations of a lizard distributed over an environmentally heteroge-neous range that has been changing since the split of eastern and western lineages ca. 3 mya. Overall, western lizards inhabit forest habitat and are unstriped, whereas eastern ones inhabit shrublands and are striped. However, one population (Lerma) has unstriped phenotype despite its eastern ancestry. The analysis of 73,291 SNPs confirmed the east–west division and identified nonoverlapping sets of outliers (12 identified by ROA and 9 by CIOA). ROA revealed ancestral adaptive variation in the uncovered outliers that were subject to divergent selection and differently fixed for eastern and western populations at the extremes of the environmental gradient. Interestingly, such variation was maintained in Lerma, where we found high levels of heterozygosity for ROA outliers, whereas CIOA uncovered innovative variants that were selected only there. Overall, it seems that both the maintenance of ancestral variation and asymmetric migration have counterbalanced adaptive lineage split-ting in our model species. This scenario, which is likely promoted by a changing and heterogeneous environment, could hamper ecological speciation of locally adapted populations despite strong genetic structure between lineages

Low genome‐wide divergence between two lizard populations with high adaptive phenotypic differentiation

Usually, adaptive phenotypic differentiation is paralleled by genetic divergence between locally adapted populations. However, adaptation can also happen in a scenario of nonsignificant genetic divergence due to intense gene flow and/or recent differentiation. While this phenomenon is rarely published, findings on incipient ecologically driven divergence or isolation by adaptation are relatively common, which could confound our understanding about the frequency at which they actually occur in nature. Here, we explore genome-wide traces of divergence between two populations of the lacertid lizard Psammodromus algirus separated by a 600 m elevational gradient. These populations seem to be differentially adapted to their environments despite showing low levels of genetic differentiation (according to previously studies of mtDNA and microsatellite data). We performed a search for outliers (i.e., loci subject to selection) trying to identify specific loci with FST statistics significantly higher than those expected on the basis of overall, genome-wide estimates of genetic divergence. We find that local phenotypic adaptation (in terms of a wide diversity of characters) was not accompanied by genome-wide differentiation, even when we maximized the chances of unveiling such differentiation at particular loci with FSTbased outlier detection tests. Instead, our analyses confirmed the lack of genomewide differentiation on the basis of more than 70,000 SNPs, which is concordant with a scenario of local adaptation without isolation by environment. Our results add evidence to previous studies in which local adaptation does not lead to any kind of isolation (or early stages of ecological speciation), but maintains phenotypic divergence despite the lack of a differentiated genomic background

High Efficiency Power Amplifier Based on Envelope Elimination and Restoration Technique

Due to complex envelope and phase modulation employed in modern transmitters it is necessary to use power amplifiers that have high linearity. Linear power amplifiers (classes A, B and AB) are commonly used, but they suffer from low efficiency especially if the transmitted signal has high peak to average power ratio (PAPR). Kahn's technique based on envelope elimination and restoration (EER) is based on idea that high efficiency power supply (envelope amplifier) could be used to modulate the envelope of high efficient non linear power amplifiers (classes D or E). This paper presents solutions for power amplifier that performs envelope modulation and class E amplifier that is used as a non linear amplifier. The envelope amplifier is implemented as a multilevel converter in series with linear regulator and can provide up to 100 W of instantaneous power and reproduce 2 MHz sine wave. The implemented Class E amplifier can operate at 120 MHz with efficiency near to 85%. The envelope amplifier and class E amplifier have been integrated and efficiency and linearity of the implemented transmitter has been measured and presente