766 research outputs found

    Determinants of internet use by the elderly in Spain: Time dedicated to search and communications

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    Internet use reduces the isolation or exclusion of individuals in specific socio-economic groups and, consequently, increases the quality of life, with this being especially the case for the elderly. Since the elderly are becoming more active in dedicating time to the Internet, we provide evidence of the time that individuals in Spain aged 65 and older dedicate to two online activities: search and communications. Thus, our work contributes to the central objective of the Digital Agenda for Europa, which sets out to ensure universal broadband coverage across the European Union. We estimate a simultaneous SUR model with data from the 4, 036 individuals aged 65 years (inclusive) and older from the Spanish Time Use Survey for 20092010. Results indicate that being male has a positive influence on the time devoted to search on the Internet, whereas age has a negative effect. Time devoted to both Internet activities increases with higher levels of education and at the highest level of individual health. By contrast, a larger number of family members has a negative influence on the time spent on search and, more so, on communications. Finally, living in a larger city has a positive effect on the time dedicated to search

    A hybrid ARIMA and artificial neural networks model to forecast particulate matter in urban areas: The case of Temuco, Chile

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    Box-Jenkins Time Series (ARIMA) and the multivariate linear models (MLM) have been important and popular linear tools in air quality forecasting during the past decade for urban areas. On the other hand, artificial neural networks (ANN) recently have been used successfully as a nonlinear tool in several research studies of pollution forecasting. A hybrid model that combines both ARIMA and ANN tools was proposed to improve the unique capabilities of ARIMA and ANN tools in linear and non linear modeling on particulate matter forecasting. To examine the effectiveness of the proposed hybrid model over real particulate matter data, the time series of PM10 and meteorological data observed in ambient air during 2000-2006 at a site in Temuco, Chile, was used In 2005, this city was declared a non-attainment area for PM10, whose pollution is the result of a great economic growth, a fast urban expansion, woodstoves, industrial sources, and a strong diesel vehicles growth. Experimental results with meteorological and PM10 data sets indicated that the hybrid model can be an effective tool to improve the forecasting accuracy obtained by either of the models used separately, and compared with a statistical multivariate linear regression. This is an abstract of a paper presented at the 100th Annual Conference and Exhibition of the Air and Waste Management Association 2007 (Pittsburgh, PA, 6/26-29/2007)

    Xantoma intraóseo pelviano: reporte de un caso y revisión de la literatura

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    ResumenEl xantoma intraóseo (XIO) es un tumor óseo benigno extremadamente raro. En la histología se caracteriza por presentar macrófagos mononucleares, abundantes células espumosas y células gigantes multinucleadas. Puede aparecer asociado a otras enfermedades (XIO secundario), principalmente a desórdenes lipídicos, o en forma aislada (XIO primario). Los XIO son lesiones líticas expansivas que a menudo se encuentran en pacientes con condiciones hiperlipidémicas. En la mayoría de los casos la evaluación inicial se realiza con radiografía, aunque otros procedimientos pueden ser necesarios para confirmar el diagnóstico.Se presenta el caso de un hombre de 48 años que consultó por lumbalgia con irradiación al miembro inferior derecho e impotencia funcional de 3 meses de evolución. Tenía hallazgos imagenológicos de XIO en el hueso ilíaco derecho, sin hiperlipidemia o lesiones preexistentes. Se llevó a cabo la extirpación total del tumor y el posterior estudio histopatológico de la pieza operatoria confirmó el diagnóstico. El tratamiento resultó exitoso.El objetivo de este artículo es describir los hallazgos clínicos e imagenológicos (radiografía, resonancia magnética, tomografía computada y medicina nuclear) de un XIO primario y su tratamiento. Además, realizamos una breve revisión de la literatura.AbstractIntraosseous xanthoma is an extremely rare benign bone tumor. Histology shows mononuclear macrophages, abundant foam cells and multinucleated giant cells. The intraosseous xanthoma may appear associated with other diseases (secondary intraosseous xanthoma), mainly lipid disorders or without an underlying lipid disorder (primary intraosseous xanthoma). The intraosseous xanthoma is a lytic, expansive tumor, often seen in patients with hyperlipidemic conditions. In most cases, the initial evaluation is performed with X-ray, although other procedures may be necessary to confirm the diagnosis. We report the case of a man aged 48, who consulted for back pain radiating to the right leg and functional disability 3 months duration, with imaging findings in the right iliac XIO in the absence of pre-existing injuries or hyperlipidemic conditions, so surgery for total removal of the tumor was performed with histological examination of the surgical specimen, confirming the preoperative diagnosis of XIO. Such treatment resulted curative. The aim of this article is to describe the clinical, imaging findings (RX, MRI, CT, nuclear medicine) and the course of treatment of a committing the iliac primary intraosseous xanthoma a and a normolipidemic patient brief review of the literature

    Reduction of the Three Dimensional Schrodinger Equation for Multilayered Films

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    In this paper, we present a method for reducing the three dimensional Schrodinger equation to study confined metallic states, such as quantum well states, in a multilayer film geometry. While discussing some approximations that are employed when dealing with the three dimensionality of the problem, we derive a one dimensional equation suitable for studying such states using an envelope function approach. Some applications to the Cu/Co multilayer system with regard to spin tunneling/rotations and angle resolved photoemission are discussed.Comment: 14 pages, 1 figur

    Using Topological Statistics to Detect Determinism in Time Series

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    Statistical differentiability of the measure along the reconstructed trajectory is a good candidate to quantify determinism in time series. The procedure is based upon a formula that explicitly shows the sensitivity of the measure to stochasticity. Numerical results for partially surrogated time series and series derived from several stochastic models, illustrate the usefulness of the method proposed here. The method is shown to work also for high--dimensional systems and experimental time seriesComment: 23 RevTeX pages, 14 eps figures. To appear in Physical Review

    Microsatellite characterisation and sex-typing in two invasive parakeet species, the monk parakeet Myiopsitta monachus and ring-necked parakeet Psittacula krameri

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    Invasive species can have wide-ranging negative impacts, and an understanding of the process and success of invasions can be vital to determine management strategies, mitigate impacts and predict range expansions of such species. Monk parakeets (Myiopsitta monachus) and ring-necked parakeets (Psittacula krameri) are both widespread invasive species, but there has been little research into the genetic and social structure of these two species despite the potential links with invasion success. The aim of this study was to isolate novel microsatellite loci from the monk parakeet and characterise them in both monk and ring-necked parakeets in order to facilitate future investigations into their behaviour and population ecology. Sex-typing markers were also tested in both species. Of the 20 microsatellite loci assessed in 24 unrelated monk parakeets, 16 successfully amplified and were polymorphic displaying between 2 and 14 alleles (mean = 8.06). Expected heterozygosity ranged from 0.43 to 0.93 and observed heterozygosity ranged from 0.23 to 0.96. Nine of the 20 loci also successfully amplified and were polymorphic in the ring-necked parakeet, displaying between 2 and 10 alleles. Suitable markers to sex both species and a Z-linked microsatellite locus were identified. A multiplex marker set was validated for monk parakeets. These novel microsatellite loci will facilitate fine and broad-scale population genetic analyses of these two widespread invasive species

    Osmotic stress tolerance in forage oat varieties (Avena Sativa L.) based on osmotic potential trials

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    Received: April 1st, 2022 ; Accepted: December 12th, 2022 ; Published: February 7th, 2023 ; Correspondence: [email protected]; [email protected] oats (Avena sativa L.) are globally important for milk and meat production, and, to a lesser extent, for the human diet. In Mexico, oats are a strategic crop, occupying the fourth place in cultivated area, only after maize for grain, bean, and sorghum for grain. Droughts are the main problem for oat production in Mexico. This study evaluated the germination and seedling growth of several oat varieties in response to drought stress simulated by PEG-6000 treatments of different osmotic pressure in order to identify drought-resistant genotypes. The Teporaca genotype was the most outstanding in the three levels of OP compared to its control with 0.0 of Osmotic Potential (OP). The Teporaca genotype showed the largest root length and the lowest diminishment of root length under osmotic stress conditions. This genotype also had the largest shoot length in the three osmotic stress levels. Regarding root fresh weight, Babicora stands out with 98.5% and Teporaca with 43% in the most severe level. Teporaca, Menonita, and Babicora showed the outstanding root dry weights of 346.5%, 327.2%, and 251.2%, respectively. These varieties had higher root dry weight than their own controls in water in the most severe level of OP. In conclusion, the Teporaca, Menonita, and Karma genotypes showed the highest osmotic stress tolerance and could be used as sources of favorable alleles to improve oat drought tolerance

    Bond graphs in model matching control

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    Bond graphs are primarily used in the network modeling of lumped parameter physical systems, but controller design with this graphical technique is relatively unexplored. It is shown that bond graphs can be used as a tool for certain model matching control designs. Some basic facts on the nonlinear model matching problem are recalled. The model matching problem is then associated with a particular disturbance decoupling problem, and it is demonstrated that bicausal assignment methods for bond graphs can be applied to solve the disturbance decoupling problem as to meet the model matching objective. The adopted bond graph approach is presented through a detailed example, which shows that the obtained controller induces port-Hamiltonian error dynamics. As a result, the closed loop system has an associated standard bond graph representation, thereby rendering energy shaping and damping injection possible from within a graphical context

    Particulate air pollution and health effects for cardiovascular and respiratory causes over an industrial neighborhood; Linking epidemiological time series studies and the power of a health perception survey

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    Talcahuano and Hualpén counties are one of the most highly industrial-polluted coastal zones in Chile, overhanging the iron foundry industry, coal burning power plants, chemical industry, and petroleum refinery, etc. The relationship between air pollution from PM2.5 measured at the Libertad monitoring station and health effects as the daily number of deaths and hospital admissions, for specific cardiovascular and respiratory diseases were studied. The results were compared with a health perception survey applied to the local population during spring 2008. Significant statistical associations were found between daily mortality and morbidity in Talcahuano-Hualpén area for cardiovascular and respiratory diseases and daily PM2.5 concentration, coinciding with the health perception of the inhabitants from these counties. The results suggest that point sources may be responsible for increased mortality in that industrial area. This has an important implication in relation with the size and chemical composition of the particles, but also for monitoring and control strategies. This is an abstract of a paper presented at the 103rd AWMA Annual Conference and Exhibition (Alberta, Canada 6/22-25/2010)

    Molecular and functional characterisation of a putative elovl4 gene and its expression in response to dietary fatty acid profile in Atlantic bluefin tuna (Thunnus thynnus)

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    Elongation of very long-chain fatty acid 4 (Elovl4) proteins are involved in the biosynthesis of very long-chain (> C24) fatty acids and in many teleost fish species they are key enzymes in the pathway for the production of docosahexaenoic acid (DHA; 22:6n-3) from eicosapentaenoic acid (EPA; 20:5n-3). Therefore, Elovl4 may be particularly important in Atlantic bluefin tuna (ABT; Thunnus thynnus) characterised by having high DHA to EPA ratios. The present study cloned and characterised both the function and expression of an elovl4 cDNA from ABT. The Elovl4 had an open reading frame of 915 base pairs encoding a putative protein of 304 amino acids. Alignment and phylogenetic analyses indicated that the Elovl4 isoform identified in the present study was an Elovl4b. Functional characterisation demonstrated that the Elovl4b enzyme had elongase activity towards all the polyunsaturated fatty acid (PUFA) substrates assayed. The ABT Elovl4b contributed to DHA biosynthesis by elongation of EPA and DPA to 24:5n-3, the latter being desaturated to 24:6n-3 by the action of fads2 (Δ6 desaturase). Additionally, the ABT Elovl4b has a role in the biosynthesis of very long-chain PUFA up to C34, compounds of key structural roles in neural tissues such as eye and brain, which had high levels of elovl4b transcripts. Surprisingly, while the relative expression of fads2, required for the production of DHA from EPA, was increased in liver of ABT fed a diet with reduced levels of EPA and DHA, expression of elovl4b was reduced. Results indicated that ABT has enzymes necessary for endogenous production of DHA from EPA and demonstrate that Elovl4b can effectively compensate for absence of Elovl2.Versión del edito
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