Development of an international survey attitude scale: measurement equivalence, reliability, and predictive validity

Declining response rates worldwide have stimulated interest in understanding what may be influencing this decline and how it varies across countries and survey populations. In this paper, we describe the development and validation of a short 9-item survey attitude scale that measures three important constructs, thought by many scholars to be related to decisions to participate in surveys, that is, survey enjoyment, survey value, and survey burden. The survey attitude scale is based on a literature review of earlier work by multiple authors. Our overarching goal with this study is to develop and validate a concise and effective measure of how individuals feel about responding to surveys that can be implemented in surveys and panels to understand the willingness to participate in surveys and improve survey effectiveness. The research questions relate to factor structure, measurement equivalence, reliability, and predictive validity of the survey attitude scale. The data came from three probability-based panels: the German GESIS and PPSM panels and the Dutch LISS panel. The survey attitude scale proved to have a replicable three-dimensional factor structure (survey enjoyment, survey value, and survey burden). Partial scalar measurement equivalence was established across three panels that employed two languages (German and Dutch) and three measurement modes (web, telephone, and paper mail). For all three dimensions of the survey attitude scale, the reliability of the corresponding subscales (enjoyment, value, and burden) was satisfactory. Furthermore, the scales correlated with survey response in the expected directions, indicating predictive validity

Age-related transcriptional changes in gene expression in different organs of mice support the metabolic stability theory of aging

Individual differences in the rate of aging are determined by the efficiency with which an organism transforms resources into metabolic energy thus maintaining the homeostatic condition of its cells and tissues. This observation has been integrated with analytical studies of the metabolic process to derive the following principle: The metabolic stability of regulatory networks, that is the ability of cells to maintain stable concentrations of reactive oxygen species (ROS) and other critical metabolites is the prime determinant of life span. The metabolic stability of a regulatory network is determined by the diversity of the metabolic pathways or the degree of connectivity of genes in the network. These properties can be empirically evaluated in terms of transcriptional changes in gene expression. We use microarrays to investigate the age-dependence of transcriptional changes of genes in the insulin signaling, oxidative phosphorylation and glutathione metabolism pathways in mice. Our studies delineate age and tissue specific patterns of transcriptional changes which are consistent with the metabolic stability–longevity principle. This study, in addition, rejects the free radical hypothesis which postulates that the production rate of ROS, and not its stability, determines life span

The Critical State of an Inclined Layer in a Sheet Specimen with Negative Loading Biaxiality Coefficient

We study conditions for the loss of stability in a plastic deformation of a layer of weaker material in a sheet specimen. The layer is not collinear with the exterior forces acting in the sheet plane, which are orthogonal to each other and have opposite signs. The parameters of the problem are: the angle between the layer and the direction of exterior forces; the ratio of stresses due to exterior forces; the ratio of strengths of the layer material and the main material of the sheet specimen; the strengthening law of the layer material; the ratio of thicknesses of the layer and the specimen. Basing on Swift's plastic instability criterion for a deformation of the layer material, we obtain an algorithm for calculating critical stress in the layer and critical exterior loading in dependence on the indicated parameters. When contact strengthening of the layer is absent, our results have explicit analytic expressions. We find conditions under which the layer does not lower the strength of the specimen. We find conditions for the stressed state of the layer to be a pure shear and study this case.Исследуются условия потери устойчивости процесса пластического деформирования слоя из менее прочного материала в листовом образце. Слой не коллинеарен внешним силам, действующим в плоскости листа, ортогональным друг другу и имеющим разные знаки. Параметрами задачи являются: угол между слоем и направлением внешних сил; отношение напряжений, порождамых внешними силами; отношение пределов прочности материала слоя и основного материала листового образца; закон упрочнения материала слоя; отношение толщины слоя к толщине образца. На основе критерия Свифта пластической неустойчивости процесса деформирования материала слоя получен алгоритм для вычисления критической интенсивности напряжений в слое и критических внешних нагрузок в зависимости от указанных параметров. В случае отсутствия контактного упрочнения слоя полученные результаты имеют форму явных аналитических выражений. Найдены условия, при которых слой не снижает прочности образца. Найдены условия и исследован случай, когда напряженное состояние слоя является чистым сдвигом

On the influence of chemical reactor geometry on the number of steady-state operational regimes

info:eu-repo/semantics/publishe