Imputación múltiple de valores perdidos en el análisis factorial exploratorio de escalas multidimensionales: estimación de las puntuaciones de rasgos latentes

Researchers frequently have to analyze scales in which some participants have failed to respond to some items. In this paper we focus on the exploratory factor analysis of multidimensional scales (i.e., scales that consist of a number of subscales) where each subscale is made up of a number of Likert-type items, and the aim of the analysis is to estimate participants’ scores on the corresponding latent traits. Our approach uses the following steps: (1) multiple imputation creates several copies of the data, in which the missing values are imputed; (2) each copy of the data is subject to independent factor analysis, and the same number of factors is extracted from all copies; (3) all factor solutions are simultaneously orthogonally (or obliquely) rotated so that they are both (a) factorially simple, and (b) as similar to one another as possible; (4) latent trait scores are estimated for ordinal data in each copy; and (5) participants’ scores on the latent traits are estimated as the average of the estimates of the latent traits obtained in the copies. We applied the approach in a real dataset where missing responses were artificially introduced following a real pattern of non-responses and a simulation study based on artificial datasets. The results show that our approach was able to compute factor score estimates even for participants that have missing data.Los investigadores con frecuencia se enfrentan a la difícil tarea de analizar las escalas en las que algunos de los participantes no han respondido a todos los ítems. En este artículo nos centramos en el análisis factorial exploratorio de escalas multidimensionales (es decir, escalas que constan de varias de subescalas), donde cada subescala se compone de una serie de ítems de tipo Likert, y el objetivo del análisis es estimar las puntuaciones de los participantes en los rasgos latentes correspondientes. En este contexto, se propone un nuevo enfoque para hacer frente a las respuestas faltantes que se basa en (1) la imputación múltiple de las respuestas faltantes y (2) la rotación simultánea de las muestras de datos imputados. Se ha aplicado el método en una muestra de datos reales en que las respuestas que faltantes fueron introducidas artificialmente siguiendo un patrón real de respuestas faltantes, y un estudio de simulación basado en conjuntos de datos artificiales. Los resultados muestran que nuestro enfoque (en concreto, Hot-Deck de imputación múltiple seguido de rotación Consensus Promin) es capaz de calcular correctamente la puntuación factorial estimada incluso para los participantes que tienen valores perdidos

Distribution of 5-HT and DA receptors in primate prefrontal cortex: implications for pathophysiology and treatment

El pdf del artículo es la versión pre-print.The prefrontal cortex (PFC) has attracted a great research interest because of its involvement in the control of executive functions in both health and disease, and particularly in cognitive functions such as working memory. In schizophrenia, alterations in the PFC are documented at many different levels: molecular, cellular and functional. Furthermore, deficits in cognitive abilities are considered a core feature of schizophrenia and remain a major unmet medical need with respect to this disorder. In order to understand the sites of action of currently used drugs, as well as of the new experimental treatments being developed and acting in this brain region, it is important to have a detailed knowledge of the corresponding chemical neuroanatomy. Here we review current knowledge regarding the cellular localization of 5-HT1A, 5-HT2A and dopamine D1, D5, and D2, D4 receptors in primate PFC and their possible functions in the neuronal circuits of the PFC.J. de Almeida is the recipient of a fellowship from the Spanish Ministry of Education. This research was funded by the Fundació La Marató TV3 (#01/3930). Support from the Generalitat de Catalunya (Grup de Recerca de Qualitat 2005-SGR0758) is also acknowledged.Peer reviewe

A Box-Behnken Design for Optimal Extraction of Phenolics from Almond By-products

[EN] Response surface methodology (RSM) was chosen to optimize the influence of solvent pH and relative proportion, and time of extraction, regarding polyphenols and radical scavenging capacity of almond (Prunus dulcis (Mill.) D.A. Webb) by-products (hulls, shells, and skins) from an almond orchard located in the North of Portugal (Lousa, Torre de Moncorvo). The RSM model was developed according to a Box-Behnken design and the optimal conditions were set for pH 6.5, 250.0 min, and 90.0% of food quality ethanol, pH 1.5, 235.0 min, and 63.0% ethanol, and pH 1.5, 250.0 min, and 56.0% ethanol for hulls, shells, and skins, respectively. The optimal conditions were obtained applying spectrophotometric techniques because of their versatility, while the chromatographic profile of extracts obtained when applied the optimal conditions indicated the presence of 3-caffeoylquinic acid, naringenin-7-O-glucoside, kaempferol-3-O-glucoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and isorhamnetin aglycone in hulls and skins. The model designed allowed the optimization of the phenolic extraction from almond by-products, demonstrating the potential of these materials as sources of antioxidant compounds with potential industrial, pharmaceutical, and food applications.IP received financial support from the FCT-Portuguese Foundation for Science and Technology (SFRH/BD/52539/2014), under the Doctoral Programme BAgricultural Production Chains-from fork to farm (PD/00122/2012). RDP was supported by a Postdoctoral Contract (Juan de la Cierva de Incorporacion ICJI-2015-25373) from the Ministry of Economy, Industry and Competitiveness of Spain. This work is supported by the National Funds by FCT-Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2019.Prgomet, I.; Gonçalves, B.; Domínguez-Perles, R.; Pascual-Seva, N.; Barros, A. (2019). A Box-Behnken Design for Optimal Extraction of Phenolics from Almond By-products. Food Analytical Methods. 12(9):2009-2024. https://doi.org/10.1007/s12161-019-01540-520092024129Aires A, Carvalho R, Saavedra MJ (2016) Valorization of solid wastes from chestnut industry processing: extraction and optimization of polyphenols, tannins and ellagitannins and its potential for adhesives, cosmetic and pharmaceutical industry. 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Factor structure and measurement invariance of the Brief Symptom Inventory (BSI-18) in cancer patients

Background/Objective: The purpose of this study was to assess psychometric properties of the Brief Symptom Inventory (BSI-18), evaluate the measurement invariance with respect to sex, age, and tumor location, and to analyze associations between social support and sociodemographic and clinical variables among individuals with resected, non-advanced cancer. Method: A confirmatory factor analysis was conducted to explore the dimensionality of the scale and test invariance across sex, age, and tumor localization in a prospective, multicenter cohort of 877 patients who completed the BSI-18 and Multidimensional Scale of Perceived Social Support (MSPSS). Results: The results show that 3-factor and 1-factor measurement models provided a good fit to the data; however, a three-factor, second-order model was deemed more appropriate and parsimonious in this population. Alpha coefficients ranged between .75 and .88. Test of measurement invariance showed strong invariance results for sex, age, and tumor location; strong invariance over time was likewise assumed. Less perceived social support appears to correlate with all BSI factors. Conclusions: The study confirmed the tridimensional structure of the BSI-18 and invariance across age, sex, and tumor localization. We recommend using this instrument to measure anxiety, depression, and somatization in epidemiological research and clinical practice

Psychometric properties and factorial analysis of invariance of the Satisfaction with Life Scale (SWLS) in cancer patients

Purpose The purpose of this study was to assess the psychometric properties of the Satisfaction with Life Scale (SWLS), evaluate the measurement invariance with respect to sex, age, and tumor location, as well as analyze associations between life satisfaction and socio-demographic and clinical variables among individuals with resected, non-advanced cancer. Methods A confirmatory factor analysis was conducted to explore the dimensionality of the scale and test invariance across gender, age, and tumor localization in a prospective, multicenter cohort of 713 patients who completed the following scales: SWLS, Health-related Quality of Life Questionnaire (EORTC QLQ-C30), Brief Symptom Inventory (BSI-18). Results Confirmatory factor analysis results indicated that the SWLS is an essentially unidimensional instrument, providing accurate scores: both McDonald's omega and Cronbach's alpha estimates were 0.91. Strong measurement invariance was found to hold across gender, age, and tumor localization. Low satisfaction with life was associated with psychological symptoms (anxiety, depression, and somatization), and decreased quality of life (malfunction, symptoms, poor global QoL). Conclusion The SWLS is a reliable, valid satisfaction with life measurement among people with cancer and should be recommended as an indicator of psychological adjustment in oncological patients

The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method

Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment

We have measured parity-violating asymmetries in elastic electron-proton and quasi-elastic electron-deuteron scattering at Q^2 = 0.22 and 0.63 GeV^2. They are sensitive to strange quark contributions to currents in the nucleon, and to the nucleon axial current. The results indicate strange quark contributions of < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial current at these four-momentum transfers.Comment: 5 pages, 2 figures, changed references, typo, and conten