Using error bounds to compare aggregated generalized transportation models

A comparative study of aggregation error bounds for the generalized transportation problem is presented. A priori and a posteriori error bounds were derived and a computational study was performed to (a) test the correlation between the a priori, the a posteriori, and the actual error and (b) quantify the difference of the error bounds from the actual error. Based on the results we conclude that calculating the a priori error bound can be considered as a useful strategy to select the appropriate aggregation level. The a posteriori error bound provides a good quantitative measure of the actual error.

Error function approximations of interest in electrochemistry.

The error function is present in several equations describing eletrode processes. But, only approximations of this function are used. In this work, these and other approximations are studied and evaluated according to precision.

Effects of direction and curvature on variable error pattern of reaching movements

A number of studies have analyzed various indices of the final position variability in order to provide insight into different levels of neuromotor processing during reaching movements. Yet the possible effects of movement kinematics on variability have often been neglected. The present study was designed to test the effects of movement direction and curvature on the pattern of movement variable errors. Subjects performed series of reaching movements over the same distance and into the same target. However, due either to changes in starting position or to applied obstacles, the movements were performed in different directions or along the trajectories of different curvatures. The pattern of movement variable errors was assessed by means of the principal component analysis applied on the 2-D scatter of movement final positions. The orientation of these ellipses demonstrated changes associated with changes in both movement direction and curvature. However, neither movement direction nor movement curvature affected movement variable errors assessed by area of the ellipses. Therefore it was concluded that the end-point variability depends partly, but not exclusively, on movement kinematics.

Use of the Normalized Absorbance Ratio as an Internal Standardization Approach To Minimize Measurement Error in Enzyme-Linked Immunosorbent Assays for Diagnosis of Human Papillomavirus Infection

The serological detection of antibodies against human papillomavirus (HPV) antigens is a useful tool to determine exposure to genital HPV infection and in predicting the risk of infection persistence and associated lesions. Enzyme-linked immunosorbent assays (ELISAs) are commonly used for seroepidemiological studies of HPV infection but are not standardized. Intra-and interassay performance variation is difficult to control, especially in cohort studies that require the testing of specimens over extended periods. We propose the use of normalized absorbance ratios (NARs) as a standardization procedure to control for such variations and minimize measurement error. We compared NAR and ELISA optical density (OD) values for the strength of the correlation between serological results for paired visits 4 months apart and HPV-16 DNA positivity in cervical specimens from a cohort investigation of 2,048 women tested with an ELISA using HPV-16 virus-like particles. NARs were calculated by dividing the mean blank-subtracted (net) ODs by the equivalent values of a control serum pool included in the same plate in triplicate, using different dilutions. Stronger correlations were observed with NAR values than with net ODs at every dilution, with an overall reduction in nonexplained regression variability of 39%. Using logistic regression, the ranges of odds ratios of HPV-16 DNA positivity contrasting upper and lower quintiles at different dilutions and their averages were 4.73 to 5.47 for NARs and 2.78 to 3.28 for net ODs, with corresponding significant improvements in seroreactivity-risk trends across quintiles when NARs were used. The NAR standardization is a simple procedure to reduce measurement error in seroepidemiological studies of HPV infection.

Desarrollo de una base metodológica para fortalecer capacidades municipales en materia de identificación, formulación y gestión de proyectos de mejoramiento barrial

Incluye Bibliografía

Colaboración entre grupos de trabajo en el marco del plan de acción eLAC: directrices para la identificación de conceptos, estructuras, métodos e instrumentos

Incluye Bibliografía

La incorporación de tecnologías digitales en educación: modelos de identificación de buenas prácticas

Incluye bibliografía

La identificación étnica en los registros de salud: experiencias y percepciones en el pueblo mapuche de Chile y Argentina

Incluye Bibliografía

Análisis individual y contextual en la identificación de los pueblos indígenas (México, 1990-2000)

Incluye Bibliografía

Las PYMES en el mercado de bienes y servicios ambientales: identificación de oportunidades, políticas e instrumentos: estudios de caso de Argentina, Chile, Colombia y México

Incluye Bibliografía

Desarrollo de una base metodológica para fortalecer capacidades municipales en materia de identificación, formulación y gestión de proyectos de mejoramiento barrial en el Perú

Incluye Bibliografía

Criterios de identificación del origen étnico con especial referencia a los pueblos indígenas y originarios

Incluye Bibliografía

La identificación de poblaciones indígenas en los censos de América Latina

Incluye Bibliografía

Manual de identificación, formulación y evaluación de proyectos de desarrollo rural

Incluye Bibliografía