Confirmatory factor analysis of the portuguese Depression Anxiety Stress Scales-21

O objetivo deste estudo foi determinar qual dos três modelos publicados melhor caracteriza a estrutura fatorial da versão portuguesa da Depression Anxiety Stress Scale-21 (DASS-21) e avaliar sua validade e confiabilidade. Compararam-se os três modelos através de análise fatorial confirmatória da DASS-21, aplicada em 1.297 pacientes adultos, do serviço de atenção básica (66,7% mulheres; idade média=48,57 anos). A relação entre a DASS-21 e a Positive and Negative Affect Schedule (PANAS) também foi analisada. O modelo de três fatores correlacionados se ajusta melhor aos dados. A escala apresentou boa consistência interna com valores alfa observados nas subescalas, variando de 0,836 a 0,897. A correlação com a PANAS foi positiva e moderada com a escala de afeto negativa, e negativa e limitada com a escala de afeto positivo. Esses resultados corroboram a estrutura de três fatores. O teste apresentou confiabilidade adequada e validade de constructo, dando suporte ao seu uso para rastrear pacientes portugueses no serviço de atenção básica.El objetivo de este estudio fue determinar cual de los tres modelos publicados mejor caracteriza la estructura factorial de la versión portuguesa de la Depression Anxiety Stress Scale-21 (DASS-21) y evaluar su validez y confiabilidad. Se compararon los tres modelos a través de análisis factorial confirmatoria de la DASS-21, aplicada el 1.297 pacientes adultos, del servicio de atención básica (66,7% mujeres; edad Media=48,57 años). La relación entre la DASS-21 y la Positive and Negative Affect Schedule (PANAS) también fue analizada. El modelo de tres factores correlacionados se ajusta mejor a los datos. La escala presentó buena consistencia interna con valores alfa observados en las subescalas, variando de 0,836 a 0,897. La correlación con la PANAS fue positiva y comedida con la escala de afecto negativa, y negativa y limitada con la escala de afecto positivo. Esos resultados corroboran la estructura de tres factores. La prueba presentó confiabilidad adecuada y validez de constructo, dando soporte a su uso para rastrear pacientes portugueses en el servicio de atención básica.To determine which of three published models best characterizes the factor structure of the Portuguese version of the Depression Anxiety Stress Scales-21 and to assess its validity and reliability. Confirmatory factor analysis of Depression Anxiety and Stress Scale-21 for 1,297 adult, primary care outpatients (66.7% female, Mage = 48.57 years) comparing 3 models. The relationship between the Depression Anxiety Stress Scales-21 and the Positive and Negative Affect Schedule was analyzed. The correlated 3-factor model fit the data best. The scale demonstrated good internal consistency, with alpha scores of the subscales ranging from 0.836 to 0.897. Correlation with the Positive and Negative Affect Schedule was positive and moderate with the negative affect scale; it was negative and limited with the positive affect. These findings support the correlated 3-factor structure. The test demonstrated adequate reliability and construct validity, which supports its use for screening in primary care settings with Portuguese speakers

Exoplanet Characterization and the Search for Life

Over 300 extrasolar planets (exoplanets) have been detected orbiting nearby stars. We now hope to conduct a census of all planets around nearby stars and to characterize their atmospheres and surfaces with spectroscopy. Rocky planets within their star's habitable zones have the highest priority, as these have the potential to harbor life. Our science goal is to find and characterize all nearby exoplanets; this requires that we measure the mass, orbit, and spectroscopic signature of each one at visible and infrared wavelengths. The techniques for doing this are at hand today. Within the decade we could answer long-standing questions about the evolution and nature of other planetary systems, and we could search for clues as to whether life exists elsewhere in our galactic neighborhood.Comment: 7 pages, 2 figures, submitted to Astro2010 Decadal Revie

Analytic philosophy for biomedical research: the imperative of applying yesterday's timeless messages to today's impasses

The mantra that "the best way to predict the future is to invent it" (attributed to the computer scientist Alan Kay) exemplifies some of the expectations from the technical and innovative sides of biomedical research at present. However, for technical advancements to make real impacts both on patient health and genuine scientific understanding, quite a number of lingering challenges facing the entire spectrum from protein biology all the way to randomized controlled trials should start to be overcome. The proposal in this chapter is that philosophy is essential in this process. By reviewing select examples from the history of science and philosophy, disciplines which were indistinguishable until the mid-nineteenth century, I argue that progress toward the many impasses in biomedicine can be achieved by emphasizing theoretical work (in the true sense of the word 'theory') as a vital foundation for experimental biology. Furthermore, a philosophical biology program that could provide a framework for theoretical investigations is outlined

Confirmatory factor analysis of the portuguese Depression Anxiety Stress Scales-21

To determine which of three published models best characterizes the factor structure of the Portuguese version of the Depression Anxiety Stress Scales-21 and to assess its validity and reliability. Confirmatory factor analysis of Depression Anxiety and Stress Scale-21 for 1,297 adult, primary care outpatients (66.7% female, Mage = 48.57 years) comparing 3 models. The relationship between the Depression Anxiety Stress Scales-21 and the Positive and Negative Affect Schedule was analyzed. The correlated 3-factor model fit the data best. The scale demonstrated good internal consistency, with alpha scores of the subscales ranging from 0.836 to 0.897. Correlation with the Positive and Negative Affect Schedule was positive and moderate with the negative affect scale; it was negative and limited with the positive affect. These findings support the correlated 3-factor structure. The test demonstrated adequate reliability and construct validity, which supports its use for screening in primary care settings with Portuguese speakers.El objetivo de este estudio fue determinar cual de los tres modelos publicados mejor caracteriza la estructura factorial de la versión portuguesa de la Depression Anxiety Stress Scale-21 (DASS-21) y evaluar su validez y confiabilidad. Se compararon los tres modelos a través de análisis factorial confirmatoria de la DASS-21, aplicada el 1.297 pacientes adultos, del servicio de atención básica (66,7% mujeres; edad Media=48,57 años). La relación entre la DASS-21 y la Positive and Negative Affect Schedule (PANAS) también fue analizada. El modelo de tres factores correlacionados se ajusta mejor a los datos. La escala presentó buena consistencia interna con valores alfa observados en las subescalas, variando de 0,836 a 0,897. La correlación con la PANAS fue positiva y comedida con la escala de afecto negativa, y negativa y limitada con la escala de afecto positivo. Esos resultados corroboran la estructura de tres factores. La prueba presentó confiabilidad adecuada y validez de constructo, dando soporte a su uso para rastrear pacientes portugueses en el servicio de atención básica.O objetivo deste estudo foi determinar qual dos três modelos publicados melhor caracteriza a estrutura fatorial da versão portuguesa da Depression Anxiety Stress Scale-21 (DASS-21) e avaliar sua validade e confiabilidade. Compararam-se os três modelos através de análise fatorial confirmatória da DASS-21, aplicada em 1.297 pacientes adultos, do serviço de atenção básica (66,7% mulheres; idade média=48,57 anos). A relação entre a DASS-21 e a Positive and Negative Affect Schedule (PANAS) também foi analisada. O modelo de três fatores correlacionados se ajusta melhor aos dados. A escala apresentou boa consistência interna com valores alfa observados nas subescalas, variando de 0,836 a 0,897. A correlação com a PANAS foi positiva e moderada com a escala de afeto negativa, e negativa e limitada com a escala de afeto positivo. Esses resultados corroboram a estrutura de três fatores. O teste apresentou confiabilidade adequada e validade de constructo, dando suporte ao seu uso para rastrear pacientes portugueses no serviço de atenção básica

The utility of deformable image registration for small artery visualisation in contrast-enhanced whole body MR angiography

Purpose; An investigation was carried out into the effect of three image registration techniques on the diagnostic image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) images. Methods Whole-body CE-MRA data from the lower legs of 27 patients recruited onto a study of asymptomatic atherosclerosis were processed using three deformable image registration algorithms. The resultant diagnostic image quality was evaluated qualitatively in a clinical evaluation by four expert observers, and quantitatively by measuring contrast-to-noise ratios and volumes of blood vessels, and assessing the techniques’ ability to correct for varying degrees of motion. Results The first registration algorithm (‘AIR’) introduced significant stenosis-mimicking artefacts into the blood vessels’ appearance, observed both qualitatively (clinical evaluation) and quantitatively (vessel volume measurements). The other two algorithms (‘Slicer’ and ‘SEMI’) based on the normalised mutual information (NMI) concept and designed specifically to deal with variations in signal intensity as found in contrast-enhanced image data, did not suffer from this serious issue but were rather found to significantly improve the diagnostic image quality both qualitatively and quantitatively, and demonstrated a significantly improved ability to deal with the common problem of patient motion. Conclusions This work highlights both the significant benefits to be gained through the use of suitable registration algorithms and the deleterious effects of an inappropriate choice of algorithm for contrast-enhanced MRI data. The maximum benefit was found in the lower legs, where the small arterial vessel diameters and propensity for leg movement during image acquisitions posed considerable problems in making accurate diagnoses from the un-registered images

The concept of transport capacity in geomorphology

The notion of sediment-transport capacity has been engrained in geomorphological and related literature for over 50 years, although its earliest roots date back explicitly to Gilbert in fluvial geomorphology in the 1870s and implicitly to eighteenth to nineteenth century developments in engineering. Despite cross fertilization between different process domains, there seem to have been independent inventions of the idea in aeolian geomorphology by Bagnold in the 1930s and in hillslope studies by Ellison in the 1940s. Here we review the invention and development of the idea of transport capacity in the fluvial, aeolian, coastal, hillslope, débris flow, and glacial process domains. As these various developments have occurred, different definitions have been used, which makes it both a difficult concept to test, and one that may lead to poor communications between those working in different domains of geomorphology. We argue that the original relation between the power of a flow and its ability to transport sediment can be challenged for three reasons. First, as sediment becomes entrained in a flow, the nature of the flow changes and so it is unreasonable to link the capacity of the water or wind only to the ability of the fluid to move sediment. Secondly, environmental sediment transport is complicated, and the range of processes involved in most movements means that simple relationships are unlikely to hold, not least because the movement of sediment often changes the substrate, which in turn affects the flow conditions. Thirdly, the inherently stochastic nature of sediment transport means that any capacity relationships do not scale either in time or in space. Consequently, new theories of sediment transport are needed to improve understanding and prediction and to guide measurement and management of all geomorphic systems