Ansiedad dimensional: Un análisis desde la teoría clásica del formulario autodiligenciado de Zung / Dimensional anxiety: An analysis from the classical theory of the Zung self-rating anxiety scale

Introducción: A pesar del uso extendido del formulario de Zung para ansiedad no se encontraron artículos sobre la invarianza de la prueba. Objetivo: Establecer la invarianza por género del formulario para ansiedad autodiligenciado de Zung desde la Teoría Clásica. Métodos: Muestra no aleaotoria de 336 mujeres y 205 hombres estudiantes de varias universidades colombianas que diligenciaron el formulario. El análisis se realizo con análisis confimatorio de factores. Se investigó la invarianza dimensional, de configuración y métrica. Resultados: Se encontró que las invarianzas dimensional y de configuración se cumplen al demostrarse que el constructo es unidimensional en los 2 géneros, seleccionando los modelos con el Criterio de información Bayesiano y que la carga de los ítems es en general alta. No así la invarianza métrica para la cual debieron eliminarse 9 ítems para lograr invarianza en las cargas. Conclusión: El formulario de Zung presenta invarianzas dimensional, de configuración y métrica con 11 ítems. Salud UIS 2011; 43 (2): 159-166.

Introduction: There is not a published report of the invariance of anxiety Zung test, although is widely used. Objective: To stablish gender invariance of the Zung self-rating anxiety scale using Classical Test Theory. Methods: A non random sample of 336 women and 205 men students from several colombian universities that answered the scale. Confirmatory factor analysis was performed. Dimensional, configurational and metric invariance were investigated. Results: Dimensional and configurational invariance are met because for both genders theres is one dimension, using Bayesian Information Crietria as the model selection strategy, and the loadings are generally high. The metric invariance was obtained after deleting 9 items. Conclusion: Eleven items of The Zung self-rating anxiety scale show dimensional, configurational and metric invariance. Salud UIS 2011; 43 (2): 159-166.

Cluster and principal component analysis for Kováts' retention indices on apolar and polar stationary phases in gas chromatography.

An extended set of Kováts' retention indices of 137 organic compounds obtained at 405.15K with C 78 standard alkane and with standalone polar interactive groups was analyzed. The retention data determined using gas chromatography were subjected to hierarchical cluster analysis and principal component analysis to detect structure in the data and to classify retention indices and solutes alike. The statistical evaluation of the retention data explored the correlation between the retention indices of the solutes and the similarities/differences of the stationary liquids. A set of chromatographic systems was selected as possible new standards relating to linear solvation energy relationships based on the chemometric data reduction. The new molecular descriptors based on retention indices were tested in correlation models for normal boiling point and olive oil/gas partition coefficient data using ridge regression. The ridge regression provided new ways for variable selection. The normal boiling points of organic compounds can reasonably be described using retention indices on apolar (C78) and polar (trifluoro, hydroxy, bromo and cyano) model compounds. The partition coefficients between olive oil and the gas phase can similarly be well correlated with retention indices on apolar (C78) and polar (tetramethoxy, trifluoro and hydroxy) model compounds.

Field desorption mass spectrometry of large multiply branched saturated hydrocarbons.

Large multiply branched saturated hydrocarbons containing 67-103 carbon atoms (molecular masses 941.8-1446.8 Da) were analyzed by field desorption mass spectrometry (FD-MS) with a double-focusing mass spectrometer. FD-MS was found to have detection limits in the 100 fmol range. The FD mass spectra exhibited molecular ions of astonishingly low abundance. However, the fragment ions formed were closely related to the proposed molecular structure, allowing us to set up rules for straightforward structure elucidation of unknowns. In detail, (i) dehydrogenation, (ii) alkyl losses from molecular ions and (iii) subsequent alkene losses were observed. The influence of the electric field strength on dehydrogenation and C-C cleavages was examined by variation of the emitter potential. Additionally, ion dissociations in the ion source and in the first and second field-free regions, respectively, were compared to study the relative importance of field-induced and thermally induced processes.

Pair-wise interactions by gas chromatography. VII. Interaction free enthalpies of solutes with secondary alcohol groups.

A polar type liquid having a secondary alcohol substituent on a branched alkane skeleton, SOH, was used as stationary phase. The molecules of this stationary phase are nearly isomorphous and isochor with those of the branched alkane, C78, elected as standard, i.e., the molecules of both solvents have nearly the same form and the same size. Partition properties of 158 chosen molecular probes were measured by gas chromatography on SOH and on an SOH-C78 mixture having a volume fraction of thetaOH = 0.5. Based on the resulting data an interaction free enthalpy could be calculated, i.e., the additional effect of the secondary alcohol to partition. Comparison with data determined earlier on another member of this solvent family, POH, having a primary alcohol as interacting group gives information about the effect of steric hindrance on polar type solute-solvent interaction free energies.