Generalized brillinger-like transforms

Artículo científicoWe propose novel transforms of stochastic vectors, called the generalized Brillinger transforms (GBT1 and GBT2), which are generalizations of the Brillinger transform (BT). The GBT1 extends the BT to the cases when the covariance matrix and the weighting matrix are singular, and moreover, the weighting matrix is not necessarily symmetric. We show that the GBT1 may computationally be preferable over another related optimal technique, the generic Karhunen–Loève transform (GKLT). The GBT2 generalizes the GBT1 to provide, under the condition we impose, better associated accuracy than that of the GBT1. It is achieved because of the increase in a number of parameters to optimize compared to that in the GBT1

Edmond Pougin: un belga en la Centroamérica de los años 1860

International audienc

Aspectos Computacionales del Problema de Fermat-Weber y sus Algoritmos de Solución

This scientific article summarizes the most relevant computational aspects of the literature on the Fermat-Weber (FW) problem. The FW problem aims to compute a point that minimizes the sum of weighted Euclidean distances to $p$ fixed points in the plane. We present the pseudocodes, convergence analysis, computational implementation, and numerical simulations of all the methods explained in this scientific article. In the end, we give an example of image processing to determine the representative image of a set of images. All computational implementations are developed in MATLAB.Este artículo científico resume los aspectos computacionales más relevantes de la literatura sobre el problema de Fermat-Weber (FW). El problema FW tiene como objetivo calcular un punto que minimice la suma de las distancias euclidianas ponderadas a $p$ puntos fijos en el plano. Presentamos los pseudocódigos, análisis de convergencia, implementación computacional y simulaciones numéricas de todos los métodos explicados en este artículo científico. Al final, damos un ejemplo de procesamiento de imágenes para determinar la imagen representativa de un conjunto de imágenes. Todas las implementaciones computacionales se desarrollan en MATLAB

Gen-FW: Una generalización del problema de Fermat-Weber con aplicaciones al procesamiento de datos

The project "Gen-FW: A Generalization of the Fermat-Weber Problem with Applications to Data Processing" was a project affiliated with the Vicerrectoría de Investigación y Extensión (VIE) of the Instituto Tecnológico de Costa Rica during the years 2020-2022. This project proposes a generalization of the well-known Fermat-Weber problem, or simply the FW problem, in addition to studying computational aspects and applications in image processing. The FW problem calculates a vector that minimizes the sum of weighted distances with respect to other given vectors in a vector space, where the vector to be optimized is represented by a linear transformation. The FW problem has garnered growing interest due to its valuable applications in various engineering fields, such as in navigation algorithm design and establishing connectivity in mobile networks with wireless sensors, among other relevant applications. In this article, we will provide a concise yet comprehensive overview of the contributions obtained during the development of this project. The Gen-FW project offers a new perspective in the field of data processing and represents a significant advancement in solving complex problems with practical applications in various engineering areas.El proyecto "Gen-FW: Una generalización del problema de Fermat-Weber con aplicaciones al procesamiento de datos" fue un proyecto vinculado a la Vicerrectoría de Investigación y Extensión (VIE) del Instituto Tecnológico de Costa Rica durante los años 2020-2022. Este proyecto propone una generalización del conocido problema de Fermat-Weber, o simplemente problema FW, además de estudiar aspectos computacionales y aplicaciones en el procesamiento de imágenes. El problema FW calcular un vector que minimice la suma de distancias ponderadas respecto a otros vectores dados en un espacio vectorial, donde el vector a optimizar se representa mediante una transformación lineal. El problema FW ha sido objeto de un creciente interés debido a sus valiosas aplicaciones en diversas áreas de la ingeniería, por ejemplo, en el diseño de algoritmos de navegación y en el establecimiento de la conectividad de redes móviles con sensores inalámbricos, entre otras aplicaciones relevantes. En este artículo, proporcionaremos un conciso, pero completo desarrollo de las contribuciones obtenidas durante el desarrollo de dicho proyecto. El proyecto Gen-FW ofrecen una nueva perspectiva en el ámbito del procesamiento de datos y representan un avance notable en la resolución de problemas complejos con aplicaciones prácticas en diversas áreas de la ingeniería

Design and analysis of convergence and stability of iterative methods for solving nonlinear equations

[ES] Una corriente en métodos numéricos es la elaboración de nuevos métodos iterativos para la resolución de ecuaciones no lineales; se busca que estos métodos sean óptimos en contraste con su orden de convergencia y el número de evaluaciones funcionales en comparación con métodos usualmente conocidos. El presente trabajo muestra el diseño de una nueva familia paramétrica de métodos iterativos basada en la familia de métodos de Chun que contiene el esquema de Ostrowski como caso particular. Se realiza además un análisis por medio de dinámica compleja para visualizar planos de parámetros y dinámicos para seleccionar los parámetros que presentan un comportamiento más estable para el esquema en estudio y así formar un método iterativo más eficiente.[EN] One stream in numerical analysis is the creation of new iterative methods for the resolution of non-linear equations; optimal processes are sought in contrast with their order of convergence and the number of functional evaluations compared to usual known methods. This article shows a design of a new parametric family of iterative methods based on the Chun¿s family of methods which contains the particular case of the Ostrowski¿s scheme. Through an analysis with complex dynamic it is intended to visualize dynamic planes and parameters¿ planes to choose the best parameter who brings more stable behavior for the scheme under study and make it more efficient.Torregrosa Sánchez, JR.; Cordero Barbero, A.; Pablo Soto-Quiros; Armando Solís (2021). Diseño y análisis de la convergencia y estabilidad de métodos iterativos para la resolución de ecuaciones no lineales. Revista digital Matemática, Educación e Internet. 21(2):1-27. https://doi.org/10.18845/rdmei.v21i2.5602S12721

Polymorphisms in IL12A and cockroach allergy in children with asthma

<p>Abstract</p> <p>Background</p> <p>IL12A has been implicated in T-cell development and may thus influence the development of atopy and allergic diseases.</p> <p>Methods</p> <p>We tested for association between four linkage disequilibrium (LD)-tagging SNPs (rs2243123, rs2243151, rs668998, and rs17826053) in <it>IL12A </it>and asthma and allergy-related (serum total and allergen-specific IgE, and skin test reactivity [STR] to two common allergens) phenotypes in two samples: 417 Costa Rican children with asthma and their parents, and 470 families of 503 white children in the Childhood Asthma Management Program (CAMP). The analysis was conducted using the family-based association test (FBAT) statistic implemented in the PBAT program.</p> <p>Results</p> <p>Among Costa Rican children with asthma, homozygosity for the minor allele of each of two SNPs in <it>IL12A </it>(rs2243123 and rs2243151) was associated with increased risks of STR to American cockroach (P ≤ 0.03 for both SNPs), STR to German cockroach (P ≤ 0.01 for both SNPs), and having a positive IgE to German cockroach (P < 0.05 for both SNPs). Among children in CAMP, homozygosity for the minor allele of SNP rs2243151 in <it>IL12A </it>was inversely associated with STR to German cockroach (P = 0.03) and homozygosity for the minor allele of SNP rs17826053 in <it>IL12A </it>was associated with increased risks of STR to American cockroach (P = 0.01) and STR to German cockroach (P = 0.007). There was no significant association between any SNP in <it>IL12A </it>and asthma, STR to dust mite, or total IgE in Costa Rica or CAMP.</p> <p>Conclusion</p> <p>Our findings suggest that variants in <it>IL12A </it>influence cockroach allergy among children with asthma.</p

A general class of arbitrary order iterative methods for computing generalized inverses

[EN] A family of iterative schemes for approximating the inverse and generalized inverse of a complex matrix is designed, having arbitrary order of convergence p. For each p, a class of iterative schemes appears, for which we analyze those elements able to converge with very far initial estimations. This class generalizes many known iterative methods which are obtained for particular values of the parameters. The order of convergence is stated in each case, depending on the first non-zero parameter. For different examples, the accessibility of some schemes, that is, the set of initial estimations leading to convergence, is analyzed in order to select those with wider sets. This wideness is related with the value of the first non-zero value of the parameters defining the method. Later on, some numerical examples (academic and also from signal processing) are provided to confirm the theoretical results and to show the feasibility and effectiveness of the new methods. (C) 2021 The Authors. Published by Elsevier Inc.This research was supported in part by PGC2018-095896-B-C22 (MCIU/AEI/FEDER, UE) and in part by VIE from Instituto Tecnologico de Costa Rica (Research #1440037)Cordero Barbero, A.; Soto-Quiros, P.; Torregrosa Sánchez, JR. (2021). A general class of arbitrary order iterative methods for computing generalized inverses. Applied Mathematics and Computation. 409:1-18. https://doi.org/10.1016/j.amc.2021.126381S11840

Cough quality in children: a comparison of subjective vs. bronchoscopic findings

BACKGROUND: Cough is the most common symptom presenting to doctors. The quality of cough (productive or wet vs dry) is used clinically as well as in epidemiology and clinical research. There is however no data on the validity of cough quality descriptors. The study aims were to compare (1) cough quality (wet/dry and brassy/non-brassy) to bronchoscopic findings of secretions and tracheomalacia respectively and, (2) parent's vs clinician's evaluation of the cough quality (wet/dry). METHODS: Cough quality of children (without a known underlying respiratory disease) undergoing elective bronchoscopy was independently evaluated by clinicians and parents. A 'blinded' clinician scored the secretions seen at bronchoscopy on pre-determined criteria and graded (1 to 6). Kappa (K) statistics was used for agreement, and inter-rater and intra-rater agreement examined on digitally recorded cough. A receiver operating characteristic (ROC) curve was used to determine if cough quality related to amount of airway secretions present at bronchoscopy. RESULTS: Median age of the 106 children (62 boys, 44 girls) enrolled was 2.6 years (IQR 5.7). Parent's assessment of cough quality (wet/dry) agreed with clinicians' (K = 0.75, 95%CI 0.58–0.93). When compared to bronchoscopy (bronchoscopic secretion grade 4), clinicians' cough assessment had the highest sensitivity (0.75) and specificity (0.79) and were marginally better than parent(s). The area under the ROC curve was 0.85 (95%CI 0.77–0.92). Intra-observer (K = 1.0) and inter-clinician agreement for wet/dry cough (K = 0.88, 95%CI 0.82–0.94) was very good. Weighted K for inter-rater agreement for bronchoscopic secretion grades was 0.95 (95%CI 0.87–1). Sensitivity and specificity for brassy cough (for tracheomalacia) were 0.57 and 0.81 respectively. K for both intra and inter-observer clinician agreement for brassy cough was 0.79 (95%CI 0.73–0.86). CONCLUSIONS: Dry and wet cough in children, as determined by clinicians and parents has good clinical validity. Clinicians should however be cognisant that children with dry cough may have minimal to mild airway secretions. Brassy cough determined by respiratory physicians is highly specific for tracheomalacia

Predictors of repeated acute hospital attendance for asthma in children: A systematic review and meta-analysis.

BACKGROUND: Asthma attacks are common and have significant physical, psychological, and financial consequences. Improving the assessment of a child's risk of subsequent asthma attacks could support front-line clinicians' decisions on augmenting chronic treatment or specialist referral. We aimed to identify predictors for emergency department (ED) or hospital readmission for asthma from the published literature. METHODS: We searched MEDLINE, EMBASE, AMED, PsycINFO, and CINAHL with no language, location, or time restrictions. We retrieved observational studies and randomized controlled trials (RCT) assessing factors (personal and family history, and biomarkers) associated with the risk of ED re-attendance or hospital readmission for acute childhood asthma. RESULTS: Three RCTs and 33 observational studies were included, 31 from Anglophone countries and none from Asia or Africa. There was an unclear or high risk of bias in 14 of the studies, including 2 of the RCTs. Previous history of emergency or hospital admissions for asthma, younger age, African-American ethnicity, and low socioeconomic status increased risk of subsequent ED and hospital readmissions for acute asthma. Female sex and concomitant allergic diseases also predicted hospital readmission. CONCLUSION: Despite the global importance of this issue, there are relatively few high quality studies or studies from outside North America. Factors other than symptoms are associated with the risk of emergency re-attendance for acute asthma among children. Further research is required to better quantify the risk of future attacks and to assess the role of commonly used biomarkers