1,172 research outputs found

    Risk factor patterns in type 2 diabetes and cardiovascular disease : exploring methods for precision medicine in public health

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    Non-communicable diseases, including type 2 diabetes and cardiovascular disease, are leading contributors to the global burden of disease and an important public health challenge. At an individual level, there is important variability in the risk of these conditions. However, public health interventions often adopt a generalized one-size-fits-all approach. The overall aim of this thesis was to explore the utility of a precision medicine approach to public health and epidemiology, by applying different analytical methods to classify individuals into similar sub-populations based on their individual level characteristics. In study I, I investigated the patterns of weight changes from childhood to early adulthood and how they relate to the occurrence of type 2 diabetes later in life. The results indicate that exposure to overweight/obesity during early adulthood explains a large proportion of the cases of type 2 diabetes, highlighting the importance of public health interventions during this period. In study II, I used different methods for mediation analysis to study the importance of different mechanisms linking low socioeconomic status and type 2 diabetes. The findings show that around 50% of the association between socioeconomic status and type 2 diabetes could be reduced if unhealthy behaviors and metabolic exposures were removed. Interestingly, the results were similar across the different mediation methods. Finally, in studies III and IV, I used data-driven methods to identify sub-groups of healthy adults based on simple clinical characteristics and laboratory values. The findings show that this method was equally effective, or even better, than those commonly used in clinical practice, and could improve the way we define who is at high risk of type 2 diabetes or cardiovascular disease. In conclusion, these studies provide evidence that precision medicine can be a useful approach to guide development and implementation of public health interventions

    Neural-Kalman Schemes for Non-Stationary Channel Tracking and Learning

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    This Thesis focuses on channel tracking in Orthogonal Frequency-Division Multiplexing (OFDM), a widely-used method of data transmission in wireless communications, when abrupt changes occur in the channel. In highly mobile applications, new dynamics appear that might make channel tracking non-stationary, e.g. channels might vary with location, and location rapidly varies with time. Simple examples might be the di erent channel dynamics a train receiver faces when it is close to a station vs. crossing a bridge vs. entering a tunnel, or a car receiver in a route that grows more tra c-dense. Some of these dynamics can be modelled as channel taps dying or being reborn, and so tap birth-death detection is of the essence. In order to improve the quality of communications, we delved into mathematical methods to detect such abrupt changes in the channel, such as the mathematical areas of Sequential Analysis/ Abrupt Change Detection and Random Set Theory (RST), as well as the engineering advances in Neural Network schemes. This knowledge helped us nd a solution to the problem of abrupt change detection by informing and inspiring the creation of low-complexity implementations for real-world channel tracking. In particular, two such novel trackers were created: the Simpli- ed Maximum A Posteriori (SMAP) and the Neural-Network-switched Kalman Filtering (NNKF) schemes. The SMAP is a computationally inexpensive, threshold-based abrupt-change detector. It applies the three following heuristics for tap birth-death detection: a) detect death if the tap gain jumps into approximately zero (memoryless detection); b) detect death if the tap gain has slowly converged into approximately zero (memory detection); c) detect birth if the tap gain is far from zero. The precise parameters for these three simple rules can be approximated with simple theoretical derivations and then ne-tuned through extensive simulations. The status detector for each tap using only these three computationally inexpensive threshold comparisons achieves an error reduction matching that of a close-to-perfect path death/birth detection, as shown in simulations. This estimator was shown to greatly reduce channel tracking error in the target Signal-to-Noise Ratio (SNR) range at a very small computational cost, thus outperforming previously known systems. The underlying RST framework for the SMAP was then extended to combined death/birth and SNR detection when SNR is dynamical and may drift. We analyzed how di erent quasi-ideal SNR detectors a ect the SMAP-enhanced Kalman tracker's performance. Simulations showed SMAP is robust to SNR drift in simulations, although it was also shown to bene t from an accurate SNR detection. The core idea behind the second novel tracker, NNKFs, is similar to the SMAP, but now the tap birth/death detection will be performed via an arti cial neuronal network (NN). Simulations show that the proposed NNKF estimator provides extremely good performance, practically identical to a detector with 100% accuracy. These proposed Neural-Kalman schemes can work as novel trackers for multipath channels, since they are robust to wide variations in the probabilities of tap birth and death. Such robustness suggests a single, low-complexity NNKF could be reusable over di erent tap indices and communication environments. Furthermore, a di erent kind of abrupt change was proposed and analyzed: energy shifts from one channel tap to adjacent taps (partial tap lateral hops). This Thesis also discusses how to model, detect and track such changes, providing a geometric justi cation for this and additional non-stationary dynamics in vehicular situations, such as road scenarios where re ections on trucks and vans are involved, or the visual appearance/disappearance of drone swarms. An extensive literature review of empirically-backed abrupt-change dynamics in channel modelling/measuring campaigns is included. For this generalized framework of abrupt channel changes that includes partial tap lateral hopping, a neural detector for lateral hops with large energy transfers is introduced. Simulation results suggest the proposed NN architecture might be a feasible lateral hop detector, suitable for integration in NNKF schemes. Finally, the newly found understanding of abrupt changes and the interactions between Kalman lters and neural networks is leveraged to analyze the neural consequences of abrupt changes and brie y sketch a novel, abrupt-change-derived stochastic model for neural intelligence, extract some neuro nancial consequences of unstereotyped abrupt dynamics, and propose a new portfolio-building mechanism in nance: Highly Leveraged Abrupt Bets Against Failing Experts (HLABAFEOs). Some communication-engineering-relevant topics, such as a Bayesian stochastic stereotyper for hopping Linear Gauss-Markov (LGM) models, are discussed in the process. The forecasting problem in the presence of expert disagreements is illustrated with a hopping LGM model and a novel structure for a Bayesian stereotyper is introduced that might eventually solve such problems through bio-inspired, neuroscienti cally-backed mechanisms, like dreaming and surprise (biological Neural-Kalman). A generalized framework for abrupt changes and expert disagreements was introduced with the novel concept of Neural-Kalman Phenomena. This Thesis suggests mathematical (Neural-Kalman Problem Category Conjecture), neuro-evolutionary and social reasons why Neural-Kalman Phenomena might exist and found signi cant evidence for their existence in the areas of neuroscience and nance. Apart from providing speci c examples, practical guidelines and historical (out)performance for some HLABAFEO investing portfolios, this multidisciplinary research suggests that a Neural- Kalman architecture for ever granular stereotyping providing a practical solution for continual learning in the presence of unstereotyped abrupt dynamics would be extremely useful in communications and other continual learning tasks.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Luis Castedo Ribas.- Secretaria: Ana García Armada.- Vocal: José Antonio Portilla Figuera

    Estudio técnico en la producción de adoquines a partir de residuos de madera de tarimas, Cartago, Costa Rica

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    Proyecto de GraduaciĂłn (Licenciatura en IngenierĂ­a Forestal) Instituto TecnolĂłgico de Costa Rica, Escuela de IngenierĂ­a Forestal, 2014.Three different treatments were applied to wooden particles from reused pallets of Pinus sp: hot water wash, unwashed and unwashed with calcium carbonate. These wooden particles were incorporated with cement, sand and stone powder to form a mixture in different proportion in relation to weight to manufacture blocks, which were evaluated in hardening using the velocity of ultrasonic pulse (VPU) and the density during the first 21 and 15 days respectively, water absorption, modulus of rupture (MR) in flexion, abrasion resistance after 28 days of manufacture and resistance to attack by decay fungi during 16 weeks. Results showed that hardening occurs at 8 days with variation in the VPU and density. Moisture absorption varies between 15 and 22% with a tendency to decrease as the proportion decreases or as the wooden particles load decreases. MR ranged from 0.40 to 1.23 MPa and blocks with unwashed wooden particles and calcium carbonate showed the highest significant differences. In abrasion resistance, blocks with unwashed wooden particles reported the best results. Finally, it was concluded that, the mixture with 60:40 proportion (concrete: wood) for blocks with washed wooded particles and calcium carbonate, shows a good performance in all the parameters evaluated. Besides, these blocks are not attacked by decay fungi.Instituto TecnolĂłgico de Costa Rica

    Relevant economic issues concerning the optimal rate of inflation

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    JEL Classification: D60, E31, E41, E61, H21deflation, downward nominal rigidities, inflation costs and benefits, inflation differentials, price stability

    Efectos del tratamiento multidisciplinar en la obesidad infanto-juvenil: revisiĂłn sistemĂĄtica

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    Es necesario recopilar informaciĂłn acerca de los tratamientos mĂĄs eficaces en la lucha contra la obesidad infantil. En este sentido, nos centramos en el tratamiento multidisciplinar, con el objetivo de conocer si las Ășltimas investigaciones apoyan el uso de este mĂ©todo para mejorar los parĂĄmetros corporales de los jĂłvenes. Para ello, se ha utilizado las bases de datos Ovid (Medline) y Pubmed con las palabras clave “childhood obesity” and “treatment”, analizando los artĂ­culos publicados del 1 de enero de 2008 a la actualidad. Tras analizar los resultados obtenidos se comprueba la efectividad de los tratamientos multidisciplinares en la lucha contra la obesidad. No obstante, es necesario seguir investigando para encontrar las pautas mĂĄs adecuadas para cada tipo de poblaciĂłn

    Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53

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    While there are many dynamical mechanisms and models that try to explain the origin and phenomenology of the quasi-periodic oscillations (QPOs) seen in the X-ray light curves of low-mass X-ray binaries, few of them address how the radiative processes occurring in these extreme environments give rise to the rich set of variability features actually observed in these light curves. A step towards this end comes from the study of the energy and frequency dependence of the phase lags of these QPOs. Here we used a methodology that allowed us to study, for the first time, the dependence of the phase lags of all QPOs in the range of 1 Hz to 1300 Hz detected in the low-mass X-ray binary 4U 1636-53 upon energy and frequency as the source changes its states as it moves through the colour-colour diagram. Our results suggest that within the context of models of up-scattering Comptonization, the phase lags dependencies upon frequency and energy can be used to extract size scales and physical conditions of the medium that produces the lags

    Theories of peasant economy at the National Museum of Anthropology in Mexico City

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    This paper discusses the usefulness of the Semantic Conception of Scientific Theories as a tool for analyzing exhibitions in science museums. It focuses on representations of peasant economies in the National Museum of Anthropology in Mexico City, and reconstructs the conceptualization underlying said representations. The apparatus utilized for this task is based on the Structuralist Program, but presents the reconstruction as a category theory diagram instead of a set-theoretic predicate. The paper proposes a possible connection between the Museum’s conceptualization and Chayanov’s theory of the Peasant Economy. It ends with a final reflection on the structural transformations of scientific theories as they pass into the realm of popular science communicationEl artĂ­culo discute la pertinencia de la concepciĂłn semĂĄntica de las teorĂ­as cientĂ­ficas para el anĂĄlisis de exhibiciones en museos de ciencia. El trabajo aborda el modo de presentar la economĂ­a campesina indĂ­- gena en las salas etnogrĂĄficas del Museo Nacional de AntropologĂ­a de MĂ©xico (MNA), y reconstruye dicha conceptualizaciĂłn. El aparato reconstructor empleado recupera las distinciones del programa estructuralista, pero presenta la reconstrucciĂłn como un diagrama de la teorĂ­a de categorĂ­as, en lugar de un predicado conjuntista. El escrito propone un posible vĂ­nculo entre los contenidos del MNA y la teorĂ­a de Chayanov; concluye con una reflexiĂłn sobre las transformaciones estructurales que sufren las teorĂ­as cientĂ­ficas al pasar al ĂĄmbito de la divulgaciĂł

    Efectos comunitarios de los regĂ­menes agroalimentarios

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    En el presente trabajo se reconstruye el modelo de transformaciones agrosocioeconĂłmicas que subyace en The Struggle for Maize de Elizabeth Fitting, obra que interpreta un conjunto de datos etnogrĂĄficos e histĂłricos de una comunidad del sur del valle de TehuacĂĄn, MĂ©xico, en relaciĂłn con dinĂĄmicas mundiales o continentales de la producciĂłn y distribuciĂłn alimentaria. La autora apela a la teorĂ­a de los regĂ­menes agroalimentarios de Philip McMichael y otros autores para dar cuenta de un desarrollo agrosocioeconĂłmico local. La labor de acople que realiza The Struggle for Maize implica un modelo de la articulaciĂłn entre lo mundial y lo local; un modelo que podrĂ­a generalizarse para dar cuenta de dinĂĄmicas en otros escenarios. Sin embargo, hay que extraerlo pues The Struggle for Maize no lo presenta a modo de un esquema conciso y explĂ­cito. A ese fin se orienta el presente artĂ­culo: con base en la teorĂ­a de categorĂ­as, aquĂ­ se reconstruye el modelo mencionado como un diagrama de la categorĂ­a de los conjuntos. La intenciĂłn principal es explorar las posibilidades expresivas del aparato en cuestiĂłn, asĂ­ como desarrollar un modo de presentaciĂłn didĂĄctico que le permita al lector entender cabalmente la propuesta de Fitting y comprender el instrumento reconstructor empleado. El presente texto ilustra una manera de reconstruir arquitecturas conceptuales usando como ejemplo una monografĂ­a acadĂ©mica con importante impacto social, pues incide en la discusiĂłn actual sobre la soberanĂ­a alimentaria.O presente trabalho reconstrĂłi o modelo de transformaçÔes agrosocioeconĂŽmicas subjacentes a The Struggle for Maize de Elizabeth Fitting, um trabalho que interpreta um conjunto de dados etnogrĂĄficos e histĂłricos de uma comunidade do sul do Vale de TehuacĂĄn, MĂ©xico, em relação Ă  dinĂąmica global ou continental de produção e distribuição de alimentos. O autor recorre Ă  teoria dos regimes agroalimentares de Philip McMichael e outros para dar conta do desenvolvimento agrosocial local. O trabalho de acoplamento de The Struggle for Maize implica um modelo de articulação entre o global e o local; um modelo que poderia ser generalizado para levar em conta dinĂąmicas em outros cenĂĄrios. No entanto, ele deve ser extraĂ­do, pois The Struggle for Maize nĂŁo o apresenta como um esquema conciso e explĂ­cito. Este Ă© o propĂłsito deste artigo: com base na teoria das categorias, aqui reconstruĂ­mos o modelo mencionado como um diagrama da categoria dos conjuntos. A intenção principal Ă© explorar as possibilidades expressivas do aparelho em questĂŁo, bem como desenvolver um modo de apresentação didĂĄtico que permita ao leitor compreender plenamente a proposta de Fitting e compreender o instrumento reconstrutivo utilizado. O presente texto ilustra uma forma de reconstruir arquiteturas conceituais usando como exemplo uma monografia acadĂȘmica com importante impacto social, na medida em que afeta a discussĂŁo atual sobre soberania alimentar

    El Valle de los CaĂ­dos

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    Junto a El Escorial, a pocos kilĂłmetros de Madrid, se halla el valle espacioso y accidentado, que constituye las estribaciones de la Sierra de Guadarrama, y en cuya cabecera, solitario y destacado, se alza el Risco de la Nava, a cuyo fondo le sirven de cierre las cimas de Abantos, que ocultan las cĂșpulas y torres de El Escorial, mientras que al mediodĂ­a desciende bruscamente el terreno para ofrecer amplia perspectiva hacia la lejanĂ­a. Este fue el lugar elegido para la construcciĂłn del Valle de los CaĂ­dos. La obra serĂ­a una cruz colosal erguida sobre la montaña; bajo la montaña, una basĂ­lica inmensa excavada en la roca viva y tras ella el Monasterio. Tal era el esquema forjado en la mente de Franco —Caudillo de España— del monumento destinado a glorificar la memoria de los que murieron por su Patria
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