Finding Structural Information of RF Power Amplifiers using an Orthogonal Non-Parametric Kernel Smoothing Estimator

A non-parametric technique for modeling the behavior of power amplifiers is presented. The proposed technique relies on the principles of density estimation using the kernel method and is suited for use in power amplifier modeling. The proposed methodology transforms the input domain into an orthogonal memory domain. In this domain, non-parametric static functions are discovered using the kernel estimator. These orthogonal, non-parametric functions can be fitted with any desired mathematical structure, thus facilitating its implementation. Furthermore, due to the orthogonality, the non-parametric functions can be analyzed and discarded individually, which simplifies pruning basis functions and provides a tradeoff between complexity and performance. The results show that the methodology can be employed to model power amplifiers, therein yielding error performance similar to state-of-the-art parametric models. Furthermore, a parameter-efficient model structure with 6 coefficients was derived for a Doherty power amplifier, therein significantly reducing the deployment's computational complexity. Finally, the methodology can also be well exploited in digital linearization techniques.Comment: Matlab sample code (15 MB): https://dl.dropboxusercontent.com/u/106958743/SampleMatlabKernel.zi

Hacia una gramática textual en la enseñanza del inglés como lengua extranjera

En el presente trabajo se amplían propuestas anteriores acerca de una aproximación retórico-textual en el tratamiento de las formas gramaticales en el proceso de enseñanza del inglés como lengua extranjera. Esta aproximación considera la dinámica funcional de las estructuras y elementos gramaticales en la elaboración textual, esto es, sus modalidades de organización y los distintos planos de significación configurados. Se examinarán aquí los siguientes elementos gramaticales: una subclase de subjuntos, en cuanto marcas de punto de vista y de subtopicalización; los juntores, como nexos textuales; y los disjuntos, marcas actitudinales. También se argumenta que, pese al desarrollo de las ideologías y praxis comunicativas en el proceso de enseñanza, los contenidos gramaticales continúan recibiendo un tratamiento formal-oracional, que no es compatible con aquel asignado a los contenidos temático-funcionales. De ahí, la necesidad de ofrecer un tratamiento alternativo como el propuesto

A Cognitive Load-Centric Inquiry into Mathematical Problem-Solving in Moderate to High Ability Stage 4 Students: An Exploratory Study

This research project examines problem solving processes in moderate to high-ability grade 7 and 8 mathematics students using cognitive load theory as a theoretical basis. This was done using a qualitative method and thematic analysis to identify the theme of cognitive load as it arose during four audio-recorded interview sessions with the six participants. A model is presented that examines the problem solving process based on the data collected in this study. This model proposes that problem solving involves reading, internalisation and classification of a problem. The solver uses mental restructuring and solution strategies to reduce cognitive load. Metacognition is used as a cognitive load monitoring device. Prior knowledge largely determines the chosen solution path and strategies. Unresolved cognitive overload results in confusion which leads to non-solution; cognitive clarity results in a solution. The implications of this model are discussed for teachers and students

Physiology of the endocrine, cardiorespiratory and nervous systems in pinnipeds: Integrative approach and biomedical considerations

Thesis (Ph.D.) University of Alaska Fairbanks, 1997This thesis explored several aspects of the hormonal and cardiovascular physiology in pinnipeds (seals and sea lions). Plasma concentrations of the vasoactive hormones angiotensin II (Ang II), arginine vasopressin (AVP, the antidiuretic hormone) and atrial natriuretic peptide (ANP) were studied in six species of seals and sea lions. Resting levels of AVP, ANP and Ang II in these pinnipeds were similar to those reported for other vertebrate species, including humans. Age-related differences were found in the concentrations of these hormones in seals and sea lions. Geographic differences in hormone concentrations were found in Steller sea lions and harbor seals. To address the endocrine and cardiovascular responses to breath-holding (apnea) in marine mammals, heart rates and plasma levels of Ang II, AVP and ANP were studied in Weddell seal (Leptonychotes weddellii) and northern elephant seal (Mirounga angustirostris) pups during periods of spontaneous breathing (eupnea) and apnea. Ang II, AVP, and ANP, as well as the autonomic nervous system, were found to contribute differently to the control of heart rate in seal pups, depending whether the respiratory system was in eupnea or apnea. Because of changes in seals of different ages, it appeared that the integration of cardiorespiratory and hormonal function is not fully mature at birth, but develops post-natally, probably simultaneously to the development of diving behavior. These studies also suggested that the factors affecting cardiorespiratory function, including hormones, may differ by species. Plasma concentrations of AVP, ANP and Ang II were measured during food limitation and fasting in captive Steller sea lions (Eumetopias jubatus) and compared to levels in free-ranging conspecifics. The results suggest that Steller sea lions have a remarkable capacity to maintain hydrosmotic and endocrine balance during short-term food limitation and fasting. Hormonal studies did not provide conclusive evidence that Steller sea lions in Alaskan waters are currently affected by long-term food limitation