Luis Alberto Lopez Lopez - Academia.edu (original) (raw)

Papers by Luis Alberto Lopez Lopez

Research paper thumbnail of Working with Cloud-Based NASA Earth Observations Data and Tools

AGU Fall Meeting 2020, Dec 4, 2020

Research paper thumbnail of Análisis estructural de un bus de dos pisos de larga distancia durante colisiones

Ingenius, 2022

Este estudio presenta un análisis de colisiones de impacto frontal y volcamiento lateral de un au... more Este estudio presenta un análisis de colisiones de impacto frontal y volcamiento lateral de un autobús de dos pisos, conforme al Reglamento 66 y 29 de la Comisión Económica de las Naciones Unidas para Europa (UN/ECE), y el Servicio Ecuatoriano de Normalización (INEN) con su normativa 1323:2009, encargado de regular los autobuses para el transporte de pasajeros en el Ecuador. En la actualidad la mejora constante de la seguridad activa y pasiva de los autobuses con respecto a los accidentes es un tema de gran impacto social. En este contexto se analiza la colisión de un autobús de dos pisos aplicando el método de elementos finitos (MEF), el cual es sometido a diferentes escenarios de colisión como es de un impacto frontal y un volcamiento lateral, con la finalidad de estudiar los efectos de un accidente de este tipo de estructuras donde la normativa no es específica para esta clase de vehículos. Los resultados obtenidos permiten tener en cuenta consideraciones importantes al momento d...

Research paper thumbnail of Genetic divergence and seed vigour studies in fennel (Foeniculum vulgare Mill.)

Research paper thumbnail of Case, Concord and the Emergence of Default

Languages, 2020

This article provides initial evidence that the head K, which may spell out as case morphology, d... more This article provides initial evidence that the head K, which may spell out as case morphology, drives the operations of concord within the noun phrase. Evidence for this claim comes from three code-switching varieties: Basque/Spanish, German/Turkish and Russian/Kazakh. By placing the switch at the border between case morphology and the rest of the noun phrase the properties of K can be isolated and inspected. We find that if K is drawn from the lexicon of a non-concord language, constituents within the noun phrase adopt a default morphology. It is suggested that the data presented in this paper provide evidence for approaches that take Concord to be a form of Agree (probe, goal) and against an approach that takes it to be the result of feature percolation from the bottom up. An analysis of default morphology is proposed that argues that default forms are inserted as vocabulary items in syntactic terminals that, as a result of a failure of Agree, are populated with unvalued features.

Research paper thumbnail of A toolkit to generate inducible and interconvertible Drosophila transgenes

ABSTRACTThe existence of three independent binary systems for conditional gene expression (Gal4/U... more ABSTRACTThe existence of three independent binary systems for conditional gene expression (Gal4/UAS; LexA/LexAop; QF/QUAST) has greatly expanded versatile genetic analyses in the fruit fly Drosophila melanogaster; however, the experimental application of these tools is limited by the need to generate multiple collections of non-interchangeable transgenic fly strains for each inducible gene expression system. To address this practical limitation, we developed a modular vector that contains the regulatory elements from all three binary systems, enabling Gal4-, LexA- or QF-dependent expression of transgenes. Our methods also incorporate DNA elements that facilitate independent site-specific recombination and elimination of regulatory UAS, LexAop or QUAST modules with spatial and temporal control, thus offering unprecedented possibilities and logistical advantages for in vivo genetic modulation and efficient interconversion of overexpression transgenic fly lines.

Research paper thumbnail of Asymmetric Information and Affiliations in Brokered Housing Transactions

SSRN Electronic Journal, 2019

This research provides evidence on the role of information asymmetry and personal affiliations in... more This research provides evidence on the role of information asymmetry and personal affiliations in housing transactions using a novel dataset that allows observation of detailed information about the property, broker, and seller. Sellers holding a real estate license are found to obtain about 1.6 percent (or $3,200) more for their properties than unlicensed sellers, and sellers personally affiliated to a real estate licensee (e.g., spouses, siblings, parents) also obtain a premium of about the same size, all else equal. There is evidence from appraisal training that knowledge of property valuation further increases the price disparities, while informative public property records reduce price disparities. Agents and personal affiliates appear to use information advantages to time the market and capture capital gains. These new findings provide insights into the behaviors of market participants in asymmetric information environments.

Research paper thumbnail of The in vivo effect of low body temperatures on the degree of polymerization of tubulin in brain and testes: A comparison among some species of vertebrates

Comparative Biochemistry and Physiology Part A: Physiology, 1986

The tubulin of both brain and testes of the amphibian Bufo spinulosus, Leptodactylus ocellatus an... more The tubulin of both brain and testes of the amphibian Bufo spinulosus, Leptodactylus ocellatus and Odontophrynus occidentalis and of the fish Salvelinus fontinalis were partially depolymerized when the animals were maintained on ice for 90 min. Recovery of the animals at room temperature restored the normal degree of polymerization in both organs. The cerebral tubulin of the saurian Phymatura palluma and of the mammalian Myotis chiloensis instead, were not depolymerized in these conditions. The results suggest that the depolymerization in vivo of tubulin by lowering body temperature at 0-2 degrees C, is common to many, but not all species of vertebrates. The existence of a cold stabilizing factor in the brain of some species is suggested. A comparison is made between these results and those of other authors who observed microtubule disaggregation by cold with the electron microscope.

Research paper thumbnail of Herniectomy versus herniectomy with the DIAM spinal stabilization system in patients with sciatica and concomitant low back pain: results of a prospective randomized controlled multicenter trial

European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, Mar 4, 2016

To investigate the short and medium term efficacy and patient outcomes of DIAM spinal stabilizati... more To investigate the short and medium term efficacy and patient outcomes of DIAM spinal stabilization system on back pain, disability, leg pain and quality of life. 165 patients were enrolled; 146 patients with a single level disc herniation (L2 to L5) were randomized: 75 investigational (herniectomy and DIAM) and 71 control (herniectomy alone) treated and followed up for 24 months. Significant improvements overtime (P < 0.001) in both groups but not significantly different between groups for visual analog scale (VAS) back pain at 6 months (investigational -3.97 ± 2.55 vs control-3.37 ± 3.15, P = 0.228) and Oswestry Disability Index (ODI) at 12 months (-38.55 ± 20.10 vs -37.19 ± 22.61, P = 0.719). For both outcomes, there was no statistically significant difference between the groups, at all postoperative time points. Although the enrolment ended before the intended sample size (308 patients) was reached, the number of patients reaching the VAS back pain minimally clinically import...

Research paper thumbnail of Un modelo estadístico para analizar complejos interdependientes de patógenos vegetales

Revista Colombiana De Estadistica, Jun 1, 2012

Research paper thumbnail of Hipótesis y sumas de cuadrados tipo III Y IV en un enfoque a través del modelo de medias de celda

Revista Colombiana De Estadistica, 2001

ABSTRACT En este artículo se presenta una propuesta para obtener las funciones estimables y las s... more ABSTRACT En este artículo se presenta una propuesta para obtener las funciones estimables y las sumas de cuadrados tipo III y IV determinadas por el procedimiento GLM del SAS en modelos de medias de celda conectados. En el caso de tener información con celdas vacías, se construyen los contrastes e hipótesis efectivas y se ilustran los resultados obtenidos con un modelo de clasificación a dos vías con interacción.

Research paper thumbnail of A Statistical Model for Analyzing Interdependent Complex of Plant Pathogens

Revista Colombiana De Estadistica, Jun 1, 2012

Research paper thumbnail of Evaluating Statistical Methods Practiced in Two Important Areas of Quality Improvement

Quality Improvement Through Statistical Methods, 1998

This paper presents evaluations and comparisons of statistical methods practiced in factor screen... more This paper presents evaluations and comparisons of statistical methods practiced in factor screening as well as in analysis with missing data. In quality performance evaluation studies using factorial experiments, the method of a normal probability plot is routinely used for screening out factors with insignificant effect on the quality characteristic. We demonstrate that the method of a normal probability plot for factor screening can be misleading. A screened out factor may turn out to be significant in the presence of certain interactions. Three methods of analysis in the presence of missing data for explanatory or response variables are considered under the multiple linear regression model by ignoring the missing data rows, substituting the corresponding column means from the data rows with no missing data, and substituting the Yates/EM algorithm estimates for the missing data. Five illustrative examples are given. In all examples, the third method has turned out to be the winner.

Research paper thumbnail of Imputacion de datos en disenos switchback usando un modelo mixto con errores correlacionados Data Imputation in Switchback Designs Using a Mixed Model with Correlated Errors

The problem of predicting individual measurements in switchback de- signs with correlated errors ... more The problem of predicting individual measurements in switchback de- signs with correlated errors is considered. The predictions and imputations are done using the BLUP (Best Linear Unbiased Predictions), which have been suggested by Barroso et al. (1998). Three covariance structures were compared by the eigenvalues of the matrices of mean square errors. The re- sults suggest that structures � 2 I and AR(1) are better than CS.

Research paper thumbnail of Metodología para la estimación de celdas vacias con el modelo de medias celdas en diseños conectados

Revista Colombiana de Estadistica

En este artículo se proponen dos métodos para estimar celdas vacías y para imputar datos faltante... more En este artículo se proponen dos métodos para estimar celdas vacías y para imputar datos faltantes en diseños conectados en un experimento multifactorial, a partir del modelo de medias de celdas modificado. La primera propuesta tiene como soporte teórico el método de covarianza de Bartlett con base en el modelo de medias de celdas con restricción de efectos; la segunda se basa en la estimación por mínimos cuadrados con restricciones de no interacción. Además, se presenta una expresión general para estimar celdas con información faltante, con cualquiera de los métodos propuestos. Se demuestra que el estimador obtenido por el método de covarianza coincide con el de mínimos cuadrados con la restricción de no interacción entre los efectos. Se propone una metodología para determinar el número mínimo de celdas que se deben estimar para que el diseño se conecte, y además se muestra cuáles celdas son las que se deben imputar para lograr la conexión. Una vez hecha la imputación de la informa...

Research paper thumbnail of Identification of biomedical journals in Spain and Latin America

Health Information & Libraries Journal, 2015

Journals in languages other than English that publish original clinical research are often not we... more Journals in languages other than English that publish original clinical research are often not well covered in the main biomedical databases and therefore often not included in systematic reviews. This study aimed to identify Spanish language biomedical journals from Spain and Latin America and to describe their main features. Journals were identified in electronic databases, publishers&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; catalogues and local registries. Eligibility was determined by assessing data from these sources or the…

Research paper thumbnail of Evaluación situacional, estructura, dinámica y monitoreo de los sistemas de información en accidentes de tránsito en el Perú - 2009

Revista Peruana de Medicina Experimental y Salud Pública, 2010

Research paper thumbnail of Color-Based Road Sign Detection and Tracking

Lecture Notes in Computer Science

Research paper thumbnail of Advances in Natural Language Processing

Lecture Notes in Computer Science, 2008

This book constitutes the refereed proceedings of the 6th International Conference on Natural Lan... more This book constitutes the refereed proceedings of the 6th International Conference on Natural Language Processing, GoTAL 2008, Gothenburg, Sweden, August 2008. The 44 revised full papers presented together with 3 invited talks were carefully reviewed and selected from 107 submissions. The papers address all current issues in computational linguistics and monolingual and multilingual intelligent language processing - theory, methods and applications.

Research paper thumbnail of A Topology Self-adaptation Mechanism for Efficient Resource Location

Lecture Notes in Computer Science, 2006

Research paper thumbnail of Reliably Executing Tasks in the Presence of Malicious Processors

Lecture Notes in Computer Science, 2005

Research paper thumbnail of Working with Cloud-Based NASA Earth Observations Data and Tools

AGU Fall Meeting 2020, Dec 4, 2020

Research paper thumbnail of Análisis estructural de un bus de dos pisos de larga distancia durante colisiones

Ingenius, 2022

Este estudio presenta un análisis de colisiones de impacto frontal y volcamiento lateral de un au... more Este estudio presenta un análisis de colisiones de impacto frontal y volcamiento lateral de un autobús de dos pisos, conforme al Reglamento 66 y 29 de la Comisión Económica de las Naciones Unidas para Europa (UN/ECE), y el Servicio Ecuatoriano de Normalización (INEN) con su normativa 1323:2009, encargado de regular los autobuses para el transporte de pasajeros en el Ecuador. En la actualidad la mejora constante de la seguridad activa y pasiva de los autobuses con respecto a los accidentes es un tema de gran impacto social. En este contexto se analiza la colisión de un autobús de dos pisos aplicando el método de elementos finitos (MEF), el cual es sometido a diferentes escenarios de colisión como es de un impacto frontal y un volcamiento lateral, con la finalidad de estudiar los efectos de un accidente de este tipo de estructuras donde la normativa no es específica para esta clase de vehículos. Los resultados obtenidos permiten tener en cuenta consideraciones importantes al momento d...

Research paper thumbnail of Genetic divergence and seed vigour studies in fennel (Foeniculum vulgare Mill.)

Research paper thumbnail of Case, Concord and the Emergence of Default

Languages, 2020

This article provides initial evidence that the head K, which may spell out as case morphology, d... more This article provides initial evidence that the head K, which may spell out as case morphology, drives the operations of concord within the noun phrase. Evidence for this claim comes from three code-switching varieties: Basque/Spanish, German/Turkish and Russian/Kazakh. By placing the switch at the border between case morphology and the rest of the noun phrase the properties of K can be isolated and inspected. We find that if K is drawn from the lexicon of a non-concord language, constituents within the noun phrase adopt a default morphology. It is suggested that the data presented in this paper provide evidence for approaches that take Concord to be a form of Agree (probe, goal) and against an approach that takes it to be the result of feature percolation from the bottom up. An analysis of default morphology is proposed that argues that default forms are inserted as vocabulary items in syntactic terminals that, as a result of a failure of Agree, are populated with unvalued features.

Research paper thumbnail of A toolkit to generate inducible and interconvertible Drosophila transgenes

ABSTRACTThe existence of three independent binary systems for conditional gene expression (Gal4/U... more ABSTRACTThe existence of three independent binary systems for conditional gene expression (Gal4/UAS; LexA/LexAop; QF/QUAST) has greatly expanded versatile genetic analyses in the fruit fly Drosophila melanogaster; however, the experimental application of these tools is limited by the need to generate multiple collections of non-interchangeable transgenic fly strains for each inducible gene expression system. To address this practical limitation, we developed a modular vector that contains the regulatory elements from all three binary systems, enabling Gal4-, LexA- or QF-dependent expression of transgenes. Our methods also incorporate DNA elements that facilitate independent site-specific recombination and elimination of regulatory UAS, LexAop or QUAST modules with spatial and temporal control, thus offering unprecedented possibilities and logistical advantages for in vivo genetic modulation and efficient interconversion of overexpression transgenic fly lines.

Research paper thumbnail of Asymmetric Information and Affiliations in Brokered Housing Transactions

SSRN Electronic Journal, 2019

This research provides evidence on the role of information asymmetry and personal affiliations in... more This research provides evidence on the role of information asymmetry and personal affiliations in housing transactions using a novel dataset that allows observation of detailed information about the property, broker, and seller. Sellers holding a real estate license are found to obtain about 1.6 percent (or $3,200) more for their properties than unlicensed sellers, and sellers personally affiliated to a real estate licensee (e.g., spouses, siblings, parents) also obtain a premium of about the same size, all else equal. There is evidence from appraisal training that knowledge of property valuation further increases the price disparities, while informative public property records reduce price disparities. Agents and personal affiliates appear to use information advantages to time the market and capture capital gains. These new findings provide insights into the behaviors of market participants in asymmetric information environments.

Research paper thumbnail of The in vivo effect of low body temperatures on the degree of polymerization of tubulin in brain and testes: A comparison among some species of vertebrates

Comparative Biochemistry and Physiology Part A: Physiology, 1986

The tubulin of both brain and testes of the amphibian Bufo spinulosus, Leptodactylus ocellatus an... more The tubulin of both brain and testes of the amphibian Bufo spinulosus, Leptodactylus ocellatus and Odontophrynus occidentalis and of the fish Salvelinus fontinalis were partially depolymerized when the animals were maintained on ice for 90 min. Recovery of the animals at room temperature restored the normal degree of polymerization in both organs. The cerebral tubulin of the saurian Phymatura palluma and of the mammalian Myotis chiloensis instead, were not depolymerized in these conditions. The results suggest that the depolymerization in vivo of tubulin by lowering body temperature at 0-2 degrees C, is common to many, but not all species of vertebrates. The existence of a cold stabilizing factor in the brain of some species is suggested. A comparison is made between these results and those of other authors who observed microtubule disaggregation by cold with the electron microscope.

Research paper thumbnail of Herniectomy versus herniectomy with the DIAM spinal stabilization system in patients with sciatica and concomitant low back pain: results of a prospective randomized controlled multicenter trial

European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, Mar 4, 2016

To investigate the short and medium term efficacy and patient outcomes of DIAM spinal stabilizati... more To investigate the short and medium term efficacy and patient outcomes of DIAM spinal stabilization system on back pain, disability, leg pain and quality of life. 165 patients were enrolled; 146 patients with a single level disc herniation (L2 to L5) were randomized: 75 investigational (herniectomy and DIAM) and 71 control (herniectomy alone) treated and followed up for 24 months. Significant improvements overtime (P < 0.001) in both groups but not significantly different between groups for visual analog scale (VAS) back pain at 6 months (investigational -3.97 ± 2.55 vs control-3.37 ± 3.15, P = 0.228) and Oswestry Disability Index (ODI) at 12 months (-38.55 ± 20.10 vs -37.19 ± 22.61, P = 0.719). For both outcomes, there was no statistically significant difference between the groups, at all postoperative time points. Although the enrolment ended before the intended sample size (308 patients) was reached, the number of patients reaching the VAS back pain minimally clinically import...

Research paper thumbnail of Un modelo estadístico para analizar complejos interdependientes de patógenos vegetales

Revista Colombiana De Estadistica, Jun 1, 2012

Research paper thumbnail of Hipótesis y sumas de cuadrados tipo III Y IV en un enfoque a través del modelo de medias de celda

Revista Colombiana De Estadistica, 2001

ABSTRACT En este artículo se presenta una propuesta para obtener las funciones estimables y las s... more ABSTRACT En este artículo se presenta una propuesta para obtener las funciones estimables y las sumas de cuadrados tipo III y IV determinadas por el procedimiento GLM del SAS en modelos de medias de celda conectados. En el caso de tener información con celdas vacías, se construyen los contrastes e hipótesis efectivas y se ilustran los resultados obtenidos con un modelo de clasificación a dos vías con interacción.

Research paper thumbnail of A Statistical Model for Analyzing Interdependent Complex of Plant Pathogens

Revista Colombiana De Estadistica, Jun 1, 2012

Research paper thumbnail of Evaluating Statistical Methods Practiced in Two Important Areas of Quality Improvement

Quality Improvement Through Statistical Methods, 1998

This paper presents evaluations and comparisons of statistical methods practiced in factor screen... more This paper presents evaluations and comparisons of statistical methods practiced in factor screening as well as in analysis with missing data. In quality performance evaluation studies using factorial experiments, the method of a normal probability plot is routinely used for screening out factors with insignificant effect on the quality characteristic. We demonstrate that the method of a normal probability plot for factor screening can be misleading. A screened out factor may turn out to be significant in the presence of certain interactions. Three methods of analysis in the presence of missing data for explanatory or response variables are considered under the multiple linear regression model by ignoring the missing data rows, substituting the corresponding column means from the data rows with no missing data, and substituting the Yates/EM algorithm estimates for the missing data. Five illustrative examples are given. In all examples, the third method has turned out to be the winner.

Research paper thumbnail of Imputacion de datos en disenos switchback usando un modelo mixto con errores correlacionados Data Imputation in Switchback Designs Using a Mixed Model with Correlated Errors

The problem of predicting individual measurements in switchback de- signs with correlated errors ... more The problem of predicting individual measurements in switchback de- signs with correlated errors is considered. The predictions and imputations are done using the BLUP (Best Linear Unbiased Predictions), which have been suggested by Barroso et al. (1998). Three covariance structures were compared by the eigenvalues of the matrices of mean square errors. The re- sults suggest that structures � 2 I and AR(1) are better than CS.

Research paper thumbnail of Metodología para la estimación de celdas vacias con el modelo de medias celdas en diseños conectados

Revista Colombiana de Estadistica

En este artículo se proponen dos métodos para estimar celdas vacías y para imputar datos faltante... more En este artículo se proponen dos métodos para estimar celdas vacías y para imputar datos faltantes en diseños conectados en un experimento multifactorial, a partir del modelo de medias de celdas modificado. La primera propuesta tiene como soporte teórico el método de covarianza de Bartlett con base en el modelo de medias de celdas con restricción de efectos; la segunda se basa en la estimación por mínimos cuadrados con restricciones de no interacción. Además, se presenta una expresión general para estimar celdas con información faltante, con cualquiera de los métodos propuestos. Se demuestra que el estimador obtenido por el método de covarianza coincide con el de mínimos cuadrados con la restricción de no interacción entre los efectos. Se propone una metodología para determinar el número mínimo de celdas que se deben estimar para que el diseño se conecte, y además se muestra cuáles celdas son las que se deben imputar para lograr la conexión. Una vez hecha la imputación de la informa...

Research paper thumbnail of Identification of biomedical journals in Spain and Latin America

Health Information & Libraries Journal, 2015

Journals in languages other than English that publish original clinical research are often not we... more Journals in languages other than English that publish original clinical research are often not well covered in the main biomedical databases and therefore often not included in systematic reviews. This study aimed to identify Spanish language biomedical journals from Spain and Latin America and to describe their main features. Journals were identified in electronic databases, publishers&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; catalogues and local registries. Eligibility was determined by assessing data from these sources or the…

Research paper thumbnail of Evaluación situacional, estructura, dinámica y monitoreo de los sistemas de información en accidentes de tránsito en el Perú - 2009

Revista Peruana de Medicina Experimental y Salud Pública, 2010

Research paper thumbnail of Color-Based Road Sign Detection and Tracking

Lecture Notes in Computer Science

Research paper thumbnail of Advances in Natural Language Processing

Lecture Notes in Computer Science, 2008

This book constitutes the refereed proceedings of the 6th International Conference on Natural Lan... more This book constitutes the refereed proceedings of the 6th International Conference on Natural Language Processing, GoTAL 2008, Gothenburg, Sweden, August 2008. The 44 revised full papers presented together with 3 invited talks were carefully reviewed and selected from 107 submissions. The papers address all current issues in computational linguistics and monolingual and multilingual intelligent language processing - theory, methods and applications.

Research paper thumbnail of A Topology Self-adaptation Mechanism for Efficient Resource Location

Lecture Notes in Computer Science, 2006

Research paper thumbnail of Reliably Executing Tasks in the Presence of Malicious Processors

Lecture Notes in Computer Science, 2005