2,486 research outputs found
Effect of DNA repair deficiencies on the cytotoxicity of resveratrol
Numerous preclinical studies have shown that the
naturally-occurring polyphenol resveratrol may
produce health-beneficial effects in a variety of
disorders, including cancer, diabetes, Alzheimer, and
cardiovascular diseases. Resveratrol has entered
clinical trials for the prevention and treatment of
several of these disorders. This polyphenol is also
available in the market as a dietary supplement.
Experimental data have shown, however, that
resveratrol induces DNA damage in a variety of cells.
Here we review such evidence and evaluate the
cytotoxicity of resveratrol (MTT assay) in cells deficient
in several major DNA repair pathways (i.e.,
homologous recombination, non-homologous end
joining, base excision repair, nucleotide excision repair,
mismatch repair, and Fanconi anemia repair). Cells
deficient in base excision repair (EM9), nucleotide
excision repair (UV4 and UV5) and Fanconi Anemia
(KO40) were slightly hypersensitive to
resveratrol-induced cytotoxicity with respect to their
parental cells (AA8). Our results suggest that these
pathways may participate in the repair of the DNA
damage induced by resveratrol and that deficiencies in
these pathways may confer hypersensitivity to the
genotoxic activity of this dietary constituen
Curvature effects on a simplified reaction-diffusion model of biodegradation
The biodegradation process of some types of polymers occurs due to many different factors including
their morphology, structure and chemical composition. Although this is a complicated process, most
of its important stages like the diffusion of monomers and the hydrolysis reactions have been modeled
phenomenologically through reaction-diffusion equations, where the properties of the polymers were
encompassed. Using a simplified reaction-diffusion model for the biodegradation of polymers,
in this contribution we study the possible effects of the curvature of the system’s geometry in the
degradation process, which is characterized by the interaction of the corresponding reaction rate and
the diffusion coefficient. To illustrate the problem of diffusion on a curved surface we consider the
surface of a cylinder and of the so-called Gaussian bump. We show how the degradation process is
affected by the curvature of the system for the simplified model
Dalla fotografia digitale alla fotogrammetria per i Beni Culturali Documentazione e Divulgazione
Licencia Creative Commons: Reconocimiento – NoComercial (by-nc)[EN] Digital photography is considered a valuable tool for cultural heritage documentation. Surveying and photogrammetry are required to achieve metric and accurate results in drawings, 2D/3D modelling and texturing. This paper presents the photogrammetric workflow from data acquisition to photorealistic 3D modelling and four heritage documentation case studies in different sites. High resolution and high accuracy photorealistic 3D models allow experts to recreate and interact virtually with cultural heritage either before, during of after intervention. Managers and information experts of cultural heritage monuments and sites should consider photogrammetric by-products not only to enrich knowledge, improve understanding and provide scientific records but to ease dissemination of heritage resources.[IT] La fotografia digitale è considerata un valido strumento per la documentazione del patrimonio culturale. Topografia e fotogrammetria sono necessari per ottenere risultati metrici precisi nei disegni, modellazione 2D/3D e texturing. Questo articolo descrive il processo di lavoro adottato dall'acquisizione dati alla modellazione 3D fotorealistica. Inoltre, sono documentati alcuni casi studio relativi a diversi siti. I Manager e gli esperti di comunicazione sul patrimonio culturale, dovrebbero considerare la fotogrammetria uno strumento non solo per arricchire la conoscenza, per migliorare la comprensione e fornire registrazioni scientifiche, ma anche per facilitare la diffusione delle risorse del patrimonio.The authors woild lide to thank the support provided by the Spanish Ministry of Science and Innovation to the project HAR2010-18620Lerma García, JL.; Cabrelles López, M.; Navarro Tarin, S.; Fabado Salvador, S. (2013). From Digital Photography to Photogrammetry for Cultural Heritage Documentation and Dissemination. DisegnareCon. 6(12):1-8. https://doi.org/10.6092/issn.1828-5961/3850S1861
Maximum likelihood inference for a class of discrete-time Markov-switching time series models with multiple delays
Autoregressive Markov switching (ARMS) time series models are used to
represent real-world signals whose dynamics may change over time. They have
found application in many areas of the natural and social sciences, as well as
in engineering. In general, inference in this kind of systems involves two
problems: (a) detecting the number of distinct dynamical models that the signal
may adopt and (b) estimating any unknown parameters in these models. In this
paper, we introduce a class of ARMS time series models that includes many
systems resulting from the discretisation of stochastic delay differential
equations (DDEs). Remarkably, this class includes cases in which the
discretisation time grid is not necessarily aligned with the delays of the DDE,
resulting in discrete-time ARMS models with real (non-integer) delays. We
describe methods for the maximum likelihood detection of the number of
dynamical modes and the estimation of unknown parameters (including the
possibly non-integer delays) and illustrate their application with an ARMS
model of El Ni\~no--southern oscillation (ENSO) phenomenon
Una aproximación integradora al estudio del burnout en los profesores de Universidad
The aim of this paper is to use an integrative approach to identify the main correlates and/or predictors
at different levels (personal, psychosocial, occupational and outside the workplace) of the burnout dimensions.
The sample consists of 813 university professors. Results from statistical analyses show that
there are, indeed, both common and specific predictors for the different facets of the syndrome. Specifically,
while social support and optimism are selected to confirm all manifestations of burnout, other
factors (work hours per week, time in the profession, hardiness, Type A behavioural pattern, life events,
daily hassles) do increase the emergence of differential profiles. Lastly, findings are discussed and the
main conclusions are presentedEl objetivo del
presente trabajo es identificar, desde un acercamiento integrador, cuáles son los principales correlatos
y/o predictores de distintos ámbitos (personal, psicosocial, ocupacional y extralaboral) de las dimensiones
del burnout. La muestra está formada por 813 profesores de Universidad. Los resultados de los
análisis estadísticos realizados permiten constatar la existencia de predictores comunes y específicos
para las facetas del síndrome. Concretamente, mientras se confirma que el apoyo social y el optimismo
son seleccionados para explicar todas las manifestaciones del burnout, otros factores (horas de trabajo
a la semana, tiempo en la profesión, personalidad resistente, patrón de conducta Tipo A, acontecimientos
vitales, contrariedades cotidianas) acentúan la existencia de perfiles diferenciales.
Finalmente, se discuten los hallazgos y se presentan las principales conclusionesThis study was possible thanks to a grant given to the project «Análisis de los determinantes psicosociales y biológicos en el estrés laboral de los docentes universitarios» (reference PGIDT99PXI21103A; BSO2000-0475) financed by the Consellería de Educación y Ordenación Universitaria of the Xunta de Galicia and by the Ministerio de Educación y CienciaS
Big Five Personality Traits, Coping Strategies and Compulsive Buying in Spanish University Students
Personality traits and coping strategies have historically been two key elements in the field of health psychology. It is, therefore, striking that there is no study in the field of compulsive buying that integrates the most generic, decontextualized and stable aspects (traits) with those having a more marked processual and dynamic nature, which are closer to goal-based views of human nature (coping strategies). Another weakness of the compulsive buying field is that, despite the confirmed growing increase in compulsive buying in the younger age groups, most studies have been conducted with adult samples. Hence, this study seeks to clarify the role of the Big Five domains and different coping strategies in university students’ compulsive buying. The sample consisted of 1093 participants who were classified as either compulsive buyers or non-compulsive buyers. Both groups were compared regarding sociodemographic variables (gender, age), the Big Five personality traits, and coping strategies through chi-square tests or Student’s t-tests. Besides, a multivariate logistic regression analysis was conducted to determine which of these determinants might play a part in the construction of a risk profile for compulsive buying. The results showed that other than gender (specifically being female), Neuroticism and the use of such coping strategies as problem avoidance and wishful thinking are risk factors that increase the propensity for compulsive buying. The use of active coping strategies such as problem solving, cognitive restructuring and social support, as well as the Conscientiousness dimension are protection factors that decrease the likelihood of becoming a compulsive buyer. Finally, and on the basis of the findings obtained, possible guidelines are given, which, hopefully, may effectively contribute to the prevention of and/or intervention in compulsive buying among young adultsS
Value, quality, purchasing habits and repurchase intention in B2C: differences between frequent and occasional purchasers
Este estudio propone un modelo integrador de la recompra en comercio electrónico (B2C), basado en la teoría de la confirmación de expectativas, tomando como partida el modelo de Bhattacherjee extendido con el modelo de satisfacción Cronin. El modelo de investigación se ha probado con 536 compradores españoles, usando análisis multigrupo. El modelo fue capaz de explicar más del setenta por ciento de la varianza de la intención de recompra. Como resultados, la relación entre la calidad y la satisfacción es no significativa para todos los tipos de consumidores y la relación entre la utilidad y la recompra es no significativa sólo para los compradores más frecuentes. Algunas ideas para llevar a la práctica son presentadas a modo de discusión
Conocimiento, Actitudes y Practicas sobre Anticoncepción de emergencia en estudiantes de IV y V año de la carrera de medicina UNAN-Managua; ENERO 2014
La fecundidad juega un papel fundamental para la transición demográfica de un país subdesarrollado a un país moderno, un aumento de esta conlleva al aumento de la mortalidad materno-infantil, obligando a los gobiernos a destinar recursos económicos con el propósito de disminuir la mortalidad los cuales podrían ser utilizados para educación, trabajo, financiamiento a productores, proyectos sociales, entre otros. La familia nicaragüense es numerosa, fecunda. Nicaragua es un país de jóvenes y de niños: el 40% de su población es menor de 15 años. La tasa de fecundidad varía ligeramente en las distintas zonas del país. En el departamento de Managua, el promedio es de 5 hijos por mujer al concluir su período fértil. En otras ciudades del Pacífico, el promedio es de 5 y 6 hijos. En las ciudades del Atlántico es de 6 y 7 hijos por mujer. Generalmente la mujer comienza su vida sexual muy joven. Según datos del Informe "Familia y Fecundidad", el 38.28% de las mujeres han comenzado a vivir acompañadas entre los 14 y 16 años y el 72.72% entre los 14 y los 19 años. Nicaragua había experimentado el mayor incremento relativo de nacimientos en mujeres entre 15 y 19 años (1993), lo que supone aumento de riesgo materno infantil. Estudios recientes muestran que los adolescentes entre 13 y 18 años de edad ya iniciaron su vida sexual aumentando la incidencia de enfermedades de transmisión sexual y embarazos precoces. Los métodos de planificación familiar ayudan a reducir altas tasas de fecundidad, pero los adolescentes en un 78% no utilizan ningún método; un adolescente de 14 años que tiene una relación sexual sin protección, se traduce a “un fracaso en el desarrollo personal” porque no está listo física, psicológica, ni emocionalmente. Además, que trae al mundo a un hijo que no se desea, con todas las consecuencias que esto pueda acarrear. Así mismo, las PPMS (que no es un método de planificación familiar, tan solo un método de emergencia), es muy utilizada de manera irresponsable.
Alrededor del mundo existen publicaciones para colocar la anticoncepción en los países en desarrollo para mujeres y jóvenes, en el que describen el enfoque único para este producto esencial, pero poco utilizado y que sea más accesible a las mujeres y adolescentes. En Nicaragua, en las actividades de capacitación se han incluido al personal de farmacia y esta incluido en las normas de salud. Estos esfuerzos realizados para que la Anticoncepción de Emergencia sea aceptada han dado frutos ya que es conocido por los proveedores de servicios y por la población, esta disponible en las farmacias y se ha registrado como un producto que se vende en las farmacias privadas y es distribuido por ONG ́
Modeling River Runoff Temporal Behavior through a Hybrid Causal-Hydrological (HCH) Method
The uncertainty in traditional hydrological modeling is a challenge that has not yet been overcome. This research aimed to provide a new method called the hybrid causal-hydrological (HCH) method, which consists of the combination of traditional rainfall-runoff models with novel hydrological approaches based on artificial intelligence, called Bayesian causal modeling (BCM). This was implemented by building nine causal models for three sub-basins of the Barbate River Basin (SW Spain). The models were populated by gauging (observing) short runoff series and from long and short hydrological runoff series obtained from the Temez rainfall-runoff model (T-RRM). To enrich the data, all series were synthetically replicated using an ARMA model. Regarding the results, on the one hand differences in the dependence intensities between the long and short series were displayed in the dependence mitigation graphs (DMGs), which were attributable to the insufficient amount of data available from the hydrological records and to climate change processes. The similarities in the temporal dependence propagation (basin memory) and in the symmetry of DMGs validate the reliability of the hybrid methodology, as well as the results generated in this study. Consequently, water planning and management can be substantially improved with this approach
- …