The halo effect, private knowledge and retirement fund choice: A theoretical model for the case of México’s Afores

Empirical evidence shows that Mexican workers frequently chose a lower-yielding retirement savings manager over a higher-yielding one, damaging their prospects for retirement income. This research paper shows that such puzzling behavior can occur as a product of the unobservable private history between workers and the companies clustered around a common brand-name, in an example of what is known as the halo effect. To support this hypothesis, a theoretical model of private knowledge and subjective probability with long-term commitment is built. Results are consistent with the idea that private-knowledge-induced halo effect can produce a rational decision process to yield an apparently irrational outcome

Passive Portfolio Management by Indexing: A Performance Analysis of High, Medium and Low Capitalization Indices in Mexico

En una gestión pasiva de inversiones mediante indexación, el desempeño del portafolio dependerá en gran medida de la habilidad para elegir el mejor índice. En este trabajo, se estudia el desempeño de cuatro de los principales índices bursátiles en México con la intención de seleccionar el mejor de ellos para una estrategia de inversión pasiva. Para resolver esta pregunta, a partir de la razón de Sortino, se propone la sustitución del exceso de retorno promedio por una definición de probabilidad de acierto y el uso de la máxima desviación estándar sobre el retorno objetivo negativo. Las nuevas medidas de desempeño arrojan resultados diferentes a los resultados de la medida tradicional de Sortino, siendo el IPC large cap el mejor índice para una estrategia pasiva, en términos de su relación riesgo-rendimiento y objetivo de rentabilidadIn a passive investing strategy through indexation, the portfolio performance will depend largely on the ability to choose the best index. In this paper, we study the performance of four of the main stock indices in Mexico with the intention of selecting the best one for a passive investing strategy. To solve this question, departing from the Sortino ratio , a definition of probability of success substitutes the average excess return over a target and the use of the maximum standard deviation on the negative target return. The new per- formance measure gives different results to those of the traditional Sortino ratio, with the IPC large cap being the best index for a passive strategy, in terms of risk-reward ratio and return target

Agrupaciones de modelos locales con descripción externa. Aplicación a una planta de frío solar

En este artículo se presenta y analiza un método de creación de modelos formados por agrupaciones de submodelos locales lineales. La principal novedad es que la ponderación empleada con los submodelos no es la habitual, basada en el estado o parte del mismo sino que se toman exclusivamente señales instantáneas de entrada y salida del sistema. Esta elección simplifica algunos aspectos de la creación del modelo, manteniendo intacta la capacidad de representación, siendo ´esta comparada con otras técnicas. La simplificación aludida es importante pues acerca el método a la práctica industrial del control de procesos. La técnica de identificación resultante se ilustra mediante dos casos prácticos: un sistema simulado propuesto por Narendra y el sistema de captación de una planta real de producción de frío a partir de energía solar. En ambos casos se muestran los errores de generalización para la predicción a un paso y para la simulación usando gran cantidad de situaciones. Los resultados indican que es factible el uso del método propuesto como técnica simplificada aplicable en la industria.Comisión de la Comunidad Europea Proyecto de investigación HYCON FP6-51136

Modelling a wormhole structure

This paper proposes a model of a hypothetical wormhole done by using non-linear equations of a high degree of complexity to obtain exact solutions. Modelling of a wormhole implies creating a particular gravitational field with a hyperbolically symmetric and static geometric body produced for a hyper-cylindrical and symmetric rest mass that can occur in its short tunnel, and its subsequent thermodynamic study. Starting out from the metric in General Relativity, in order that a short wormhole tunnel might be modelled, it is essential to define the coordinates and covariant metric of a 4-dimensional space with three spatial coordinates and one temporal by applying the summation convention on repeated indices in the system of four generalized coordinates. The limiting form of the line element for flat spacetime at large distances from the origin must be Lorentzian. The line element corresponding to the solution proposed here has to remain invariant under inversion of time interval. In this paper, the simplest quadratic scalar invariant of the Riemann tensor, the Kretschmann invariant, has been taken. Furtehmore, curvilinear coordinates in which the metric tensor components that are outside the main diagonal and that have to have zero value for not having a determined direction in space have been used. The metric can be reduced to a flat metric for an observer at rest located in the “infinite” so that the effects caused by the mass in the gravitational field could be deemed negligible. The results obtained a quasi-exact solution to the Einstein’s equations that describes the gravitational field induced for a hyper-cylindrical geometry similar to a wormhole tunnel. The so-called “exotic matter” that is hypothesized to reside inside wormhole tunnels and is involved in the energy transport phenomenon has subsequently been studied

Standard and Embedded Solitons in Nematic Optical Fibers

A model for a non-Kerr cylindrical nematic fiber is presented. We use the multiple scales method to show the possibility of constructing different kinds of wavepackets of transverse magnetic (TM) modes propagating through the fiber. This procedure allows us to generate different hierarchies of nonlinear partial differential equations (PDEs) which describe the propagation of optical pulses along the fiber. We go beyond the usual weakly nonlinear limit of a Kerr medium and derive an extended Nonlinear Schrodinger equation (eNLS) with a third order derivative nonlinearity, governing the dynamics for the amplitude of the wavepacket. In this derivation the dispersion, self-focussing and diffraction in the nematic are taken into account. Although the resulting nonlinear $PDE$ may be reduced to the modified Korteweg de Vries equation (mKdV), it also has additional complex solutions which include two-parameter families of bright and dark complex solitons. We show analytically that under certain conditions, the bright solitons are actually double embedded solitons. We explain why these solitons do not radiate at all, even though their wavenumbers are contained in the linear spectrum of the system. Finally, we close the paper by making comments on the advantages as well as the limitations of our approach, and on further generalizations of the model and method presented.Comment: "Physical Review E, in press

Potential impacts of climate variability on Dengue Hemorrhagic Fever in Honduras, 2010

Climate change and variability are affecting human health and disease direct or indirectly through many mechanisms. Dengue is one of those diseases that is strongly influenced by climate variability; however its study in Central America has been poorly approached. In this study, we assessed potential associations between macroclimatic and microclimatic variation and dengue hemorrhagic fever (DHF) cases in the main hospital of Honduras during 2010. In this year, 3,353 cases of DHF were reported in the Hospital Escuela, Tegucigalpa. Climatic periods marked a difference of 158% in the mean incidence of cases, from El Niño weeks (-99% of cases below the mean incidence) to La Niña months (+59% of cases above it) (p<0.01). Linear regression showed significantly higher dengue incidence with lower values of Oceanic Niño Index (p=0.0097), higher rain probability (p=0.0149), accumulated rain (p=0.0443) and higher relative humidity (p=0.0292). At a multiple linear regression model using those variables, ONI values shown to be the most important and significant factor found to be associated with the monthly occurrence of DHF cases (r2=0.649; βstandardized=–0.836; p=0.01). As has been shown herein, climate variability is an important element influencing the dengue epidemiology in Honduras. However, it is necessary to extend these studies in this and other countries in the Central America region, because these models can be applied for surveillance as well as for prediction of dengue

Systematic identification of phenotypically enriched loci using a patient network of genomic disorders

Background Network medicine is a promising new discipline that combines systems biology approaches and network science to understand the complexity of pathological phenotypes. Given the growing availability of personalized genomic and phenotypic profiles, network models offer a robust integrative framework for the analysis of "omics" data, allowing the characterization of the molecular aetiology of pathological processes underpinning genetic diseases. Methods Here we make use of patient genomic data to exploit different network-based analyses to study genetic and phenotypic relationships between individuals. For this method, we analyzed a dataset of structural variants and phenotypes for 6,564 patients from the DECIPHER database, which encompasses one of the most comprehensive collections of pathogenic Copy Number Variations (CNVs) and their associated ontology-controlled phenotypes. We developed a computational strategy that identifies clusters of patients in a synthetic patient network according to their genetic overlap and phenotype enrichments. Results Many of these clusters of patients represent new genotype-phenotype associations, suggesting the identification of newly discovered phenotypically enriched loci (indicative of potential novel syndromes) that are currently absent from reference genomic disorder databases such as ClinVar, OMIM or DECIPHER itself. Conclusions We provide a high-resolution map of pathogenic phenotypes associated with their respective significant genomic regions and a new powerful tool for diagnosis of currently uncharacterized mutations leading to deleterious phenotypes and syndromes

"Análisis con Google Trends y Our World in Data sobre la salud mental mundial en el contexto de la pandemia por covid-19"

"Introducción: Durante la pandemia de la covid-19 los servicios de salud mental no pudieron darse abasto debido a la gran demanda, por lo cual, muchas personas optaron por buscar información por Internet que las pudiera ayudar a sobrellevar el proceso psicológico que estaban experimentando en ese momento. Objetivo: Caracterizar la tendencia mundial de búsqueda del término «psiquiatría» en el contexto de covid-19 mediante Google Trends y Our World in Data. Métodos: Estudio descriptivo-transversal sobre las tendencias mundiales de búsquedas de información sobre psiquiatría en el contexto de la covid-19 bajo los términos «psiquiatría», «depresión», «ansiedad», «estrés», «insomnio» y «suicidio» en la categoría de salud en el periodo del 2020-2021. Se generaron gráficos temporales. Resultados: El término «psiquiatría» se mantuvo con un volumen relativo de búsqueda elevado y constante (entre 60 y 90), con una búsqueda importante y paulatina en el mes de abril. El volumen relativo de búsquedas de «depresión», «ansiedad» y «estrés» se mantuvieron constantes con ciertas fluctuaciones no significativas a lo largo del periodo 2020-2021. El término «insomnio» tuvo una predominancia entre enero y junio del 2020, fue decayendo poco a poco desde abril y se mantuvo constante hasta octubre del 2021. Finalmente, el término «suicidio» obtuvo un VRB fluctuante entre 60 y 100 durante este periodo. Conclusiones: Durante el periodo de estudio los temas relacionados con la salud mental y la especialidad de psiquiatría se mantuvieron constantes, con algunas variaciones fluctuantes pero no llamativas.

Potential impacts of climate variability on Dengue Hemorrhagic Fever in Honduras, 2010

Climate change and variability are affecting human health and disease direct or indirectly through many mechanisms. Dengue is one of those diseases that is strongly influenced by climate variability; however its study in Central America has been poorly approached. In this study, we assessed potential associations between macroclimatic and microclimatic variation and dengue hemorrhagic fever (DHF) cases in the main hospital of Honduras during 2010. In this year, 3,353 cases of DHF were reported in the Hospital Escuela, Tegucigalpa. Climatic periods marked a difference of 158% in the mean incidence of cases, from El Niño weeks (-99% of cases below the mean incidence) to La Niña months (+59% of cases above it) (p<0.01). Linear regression showed significantly higher dengue incidence with lower values of Oceanic Niño Index (p=0.0097), higher rain probability (p=0.0149), accumulated rain (p=0.0443) and higher relative humidity (p=0.0292). At a multiple linear regression model using those variables, ONI values shown to be the most important and significant factor found to be associated with the monthly occurrence of DHF cases (r2=0.649; βstandardized=–0.836; p=0.01). As has been shown herein, climate variability is an important element influencing the dengue epidemiology in Honduras. However, it is necessary to extend these studies in this and other countries in the Central America region, because these models can be applied for surveillance as well as for prediction of dengue