1,178 research outputs found
Risk factor patterns in type 2 diabetes and cardiovascular disease : exploring methods for precision medicine in public health
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
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
Proyecto de Graduación (Licenciatura en Ingeniería Forestal) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería 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 Tecnológico de Costa Rica
Propuesta de un sistema de gestión de inventarios y almacenes para reducir los costos de la sub área de almacenamiento de producto terminado en la empresa Danper Trujillo S.A.C.
El autor no autorizó la publicación de la tesis
Relevant economic issues concerning the optimal rate of inflation
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: revisión sistemática
Es necesario recopilar información acerca de los tratamientos más eficaces en la lucha contra
la obesidad infantil. En este sentido, nos centramos en el tratamiento multidisciplinar, con el
objetivo de conocer si las últimas investigaciones apoyan el uso de este método para mejorar
los parámetros corporales de los jóvenes. Para ello, se ha utilizado las bases de datos Ovid
(Medline) y Pubmed con las palabras clave “childhood obesity” and “treatment”, analizando
los artículos 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 más
adecuadas para cada tipo de población
Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53
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
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 artículo discute la pertinencia de la concepción semántica de las teorías científicas para el análisis de exhibiciones en museos de ciencia. El trabajo aborda el modo de presentar la economía campesina indí- gena en las salas etnográficas del Museo Nacional de Antropología de México (MNA), y reconstruye dicha conceptualización. El aparato reconstructor empleado recupera las distinciones del programa estructuralista, pero presenta la reconstrucción como un diagrama de la teoría de categorías, en lugar de un predicado conjuntista. El escrito propone un posible vínculo entre los contenidos del MNA y la teoría de Chayanov; concluye con una reflexión sobre las transformaciones estructurales que sufren las teorías científicas al pasar al ámbito de la divulgació
Efectos comunitarios de los regímenes agroalimentarios
En el presente trabajo se reconstruye el modelo de transformaciones agrosocioeconómicas que subyace en The Struggle for Maize de Elizabeth Fitting, obra que interpreta un conjunto de datos etnográficos e históricos de una comunidad del sur del valle de Tehuacán, México, en relación con dinámicas mundiales o continentales de la producción y distribución alimentaria. La autora apela a la teoría de los regímenes agroalimentarios de Philip McMichael y otros autores para dar cuenta de un desarrollo agrosocioeconómico local. La labor de acople que realiza The Struggle for Maize implica un modelo de la articulación entre lo mundial y lo local; un modelo que podría generalizarse para dar cuenta de dinámicas en otros escenarios. Sin embargo, hay que extraerlo pues The Struggle for Maize no lo presenta a modo de un esquema conciso y explícito. A ese fin se orienta el presente artículo: con base en la teoría de categorías, aquí se reconstruye el modelo mencionado como un diagrama de la categoría de los conjuntos. La intención principal es explorar las posibilidades expresivas del aparato en cuestión, así como desarrollar un modo de presentación didáctico 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 monografía académica con importante impacto social, pues incide en la discusión actual sobre la soberanía alimentaria.O presente trabalho reconstrói o modelo de transformações agrosocioeconômicas subjacentes a The Struggle for Maize de Elizabeth Fitting, um trabalho que interpreta um conjunto de dados etnográficos e históricos de uma comunidade do sul do Vale de Tehuacán, México, em relação à dinâmica global ou continental de produção e distribuição de alimentos. O autor recorre à 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 dinâmicas em outros cenários. No entanto, ele deve ser extraído, pois The Struggle for Maize não o apresenta como um esquema conciso e explícito. Este é o propósito deste artigo: com base na teoria das categorias, aqui reconstruímos o modelo mencionado como um diagrama da categoria dos conjuntos. A intenção principal é explorar as possibilidades expressivas do aparelho em questão, bem como desenvolver um modo de apresentação didático 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 acadêmica com importante impacto social, na medida em que afeta a discussão atual sobre soberania alimentar
Effects on density, shrinking, color changing and chemical surface analysis through FTIR of Tectona grandis thermo-treated: Density, shrinking, color changing and chemical analysis by FTIR of the thermally-treated teak wood
Artículo científicoThermal-treatment wood is used as an option to improve durability of wood in recent years. This study
evaluated the effect of temperature in thermally treated Tectona grandis wood in density, shrinking, color
changing (L*a*b* system) and surface analysis through FTIR. Sapwood and heartwood boards sawn with
radial and tangential patterns were exposed to three temperature-levels: 210 ºC, 215 ºC, 220 °C during
6 hours and thermally treated wood properties were compared with untreated wood. Results showed that
density decreased from 0.61 to 0.49 g cm-3 with a tendency to decrease as temperature increases. Wood
shrinking ranges from 2.61 to 1.58 % and no statistical differences between temperatures were found. The
FTIR analysis showed a slight increase in the bands at 1024 cm-1, 1098 cm-1, 1131 cm-1, 1249 cm-1 2928
cm-1 and 3340 cm-1 with the temperature increases, indicating a lignin change. Color change showed major
changes in luminosity (L*), followed by redness (a*); while yellowness (b*) showed minor changes. Finally,
the thermal treatment at 220 °C had the best results regarding the evaluated properties
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