1,098 research outputs found

    Exploring and linking biomedical resources through multidimensional semantic spaces

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    Background The semantic integration of biomedical resources is still a challenging issue which is required for effective information processing and data analysis. The availability of comprehensive knowledge resources such as biomedical ontologies and integrated thesauri greatly facilitates this integration effort by means of semantic annotation, which allows disparate data formats and contents to be expressed under a common semantic space. In this paper, we propose a multidimensional representation for such a semantic space, where dimensions regard the different perspectives in biomedical research (e.g., population, disease, anatomy and protein/genes). Results This paper presents a novel method for building multidimensional semantic spaces from semantically annotated biomedical data collections. This method consists of two main processes: knowledge and data normalization. The former one arranges the concepts provided by a reference knowledge resource (e.g., biomedical ontologies and thesauri) into a set of hierarchical dimensions for analysis purposes. The latter one reduces the annotation set associated to each collection item into a set of points of the multidimensional space. Additionally, we have developed a visual tool, called 3D-Browser, which implements OLAP-like operators over the generated multidimensional space. The method and the tool have been tested and evaluated in the context of the Health-e-Child (HeC) project. Automatic semantic annotation was applied to tag three collections of abstracts taken from PubMed, one for each target disease of the project, the Uniprot database, and the HeC patient record database. We adopted the UMLS Meta-thesaurus 2010AA as the reference knowledge resource. Conclusions Current knowledge resources and semantic-aware technology make possible the integration of biomedical resources. Such an integration is performed through semantic annotation of the intended biomedical data resources. This paper shows how these annotations can be exploited for integration, exploration, and analysis tasks. Results over a real scenario demonstrate the viability and usefulness of the approach, as well as the quality of the generated multidimensional semantic spaces

    V405 Peg (RBS 1955): A Nearby, Low-Luminosity Cataclysmic Binary

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    (Abridged). The cataclysmic binary V405 Peg, originally discovered as ROSAT Bright Source (RBS) 1955 (= 1RXS J230949.6+213523), shows a strong contribution from a late-type secondary star in its optical spectrum, which led Schwope et al. to suggest it to be among the nearest cataclysmic binaries. We present extensive optical observations of V405 Peg. Time-series spectroscopy shows the orbital period, Porb, to be 0.1776469(7) d (= 4.2635 hr), or 5.629 cycle/d. We classify the secondary as M3 - M4.5. Astrometry with the MDM 2.4m telescope gives a parallax 7.2 +- 1.1 milli-arcsec, and a relative proper motion of 58 mas/yr. Our best estimate of the distance yields d = 149 (+26, -20) pc. The secondary stars's radial velocity has K2 = 92 +- 3 km/s, indicating a fairly low orbital inclination if the masses are typical. Extensive I-band time-series observations in the show the system varying between a minimum brightness level of I = 14.14 and states of enhanced activity about 0.2 mag brighter. While the low-state shows an ellipsoidal modulation, an additional photometric modulation appears in the high state, with 0.1 mag amplitude and period 220-280 min. The frequency of this modulation appears to be stable for a month or so, but no single period was consistently detected from one observing season to the next. We estimate the system luminosity by combining optical measurements with the archival X-ray spectrum. The implied mass accretion rate is orders of magnitudes below the predictions for the standard angular momentum loss above the period gap. The system may possibly belong to a largely undiscovered population of hibernating CVs.Comment: 11 figures; 7 of these are .png or .jpg to save space. In press for Publications of the Astronomical Society of the Pacifi

    Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample

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    Detached white dwarf + main sequence (WD+MS) systems represent the simplest population of post-common envelope binaries (PCEBs). Since the ensemble properties of this population carries important information about the characteristics of the common-envelope (CE) phase, it deserves close scrutiny. However, most population synthesis studies do not fully take into account the effects of the observational selection biases of the samples used to compare with the theoretical simulations. Here we present the results of a set of detailed Monte Carlo simulations of the population of WD+MS binaries in the Sloan Digital Sky Survey (SDSS) Data Release 7. We used up-to-date stellar evolutionary models, a complete treatment of the Roche lobe overflow episode, and a full implementation of the orbital evolution of the binary systems. Moreover, in our treatment we took into account the selection criteria and all the known observational biases. Our population synthesis study allowed us to make a meaningful comparison with the available observational data. In particular, we examined the CE efficiency, the possible contribution of internal energy, and the initial mass ratio distribution (IMRD) of the binary systems. We found that our simulations correctly reproduce the properties of the observed distribution of WD+MS PCEBs. In particular, we found that once the observational biases are carefully taken into account, the distribution of orbital periods and of masses of the WD and MS stars can be correctly reproduced for several choices of the free parameters and different IMRDs, although models in which a moderate fraction (<=10%) of the internal energy is used to eject the CE and in which a low value of CE efficiency is used (<=0.3) seem to fit better the observational data. We also found that systems with He-core WDs are over-represented in the observed sample, due to selection effects.Comment: 15 pages, 7 figures, accepted for publication in A&

    Detached cataclysmic variables are crossing the orbital period gap

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    A central hypothesis in the theory of cataclysmic variable (CV) evolution is the need to explain the observed lack of accreting systems in the ~2-3 h orbital period range, known as the period gap. The standard model, disrupted magnetic braking (DMB), reproduces the gap by postulating that CVs transform into inconspicuous detached white dwarf (WD) plus main sequence (MS) systems, which no longer resemble CVs. However, observational evidence for this standard model is currently indirect and thus this scenario has attracted some criticism throughout the last decades. Here we perform a simple but exceptionally strong test of the existence of detached CVs (dCVs). If the theory is correct dCVs should produce a peak in the orbital period distribution of detached close binaries consisting of a WD and an M4-M6 secondary star. We measured six new periods which brings the sample of such binaries with known periods below 10 h to 52 systems. An increase of systems in the ~2-3 h orbital period range is observed. Comparing this result with binary population models we find that the observed peak can not be reproduced by PCEBs alone and that the existence of dCVs is needed to reproduce the observations. Also, the WD mass distribution in the gap shows evidence of two populations in this period range, i.e. PCEBs and more massive dCVs, which is not observed at longer periods. We therefore conclude that CVs are indeed crossing the gap as detached systems, which provides strong support for the DMB theory.Comment: 12 pages, 6 figures, 2 tables, accepted for publication in MNRA

    Impacto del consejo médico para dejar de fumar durante la gestación

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    ObjetivoEl consumo de tabaco entre las mujeres ha aumentado en España en los últimos años, especialmente entre los grupos en edad reproductiva. El objetivo del estudio es evaluar el impacto del consejo médico integrado en la atención prenatal sobre el consumo de tabaco durante el embarazo y en el posparto.DiseñoEstudio de intervención cuasiexperimental.EmplazamientoHospital del Mar de Barcelona.PacientesEl grupo control estaba constituido por 219 pacientes que acudieron para atención al parto al hospital del Mar en 1996, el grupo de intervención, por 169 pacientes atendidas durante el embarazo en el mismo hospital en 1997.IntervencionesLas pacientes del grupo control habían recibido atención habitual. Las gestantes del grupo de intervención recibieron de forma sistemática un consejo estructurado para dejar de fumar, reforzado por un folleto elaborado con esta finalidad.Mediciones y resultadosLos grupos de intervención y control no presentaban diferencias estadísticamente significativas en las variables sociodemográficas ni en el consumo de tabaco. En ambos grupos se determinó la evolución del hábito tabáquico durante el embarazo a lo largo de las visitas prenatales, y a los 6 meses posparto, a través de una entrevista telefónica. De las gestantes del grupo control, 44 (20,1%) habían dejado de fumar antes de la primera visita prenatal y 11 (5%) lo hicieron durante el embarazo. En el grupo de intervención 26 (17,7%) habían dejado de fumar espontáneamente y 16 (10,9%) dejaron de fumar durante el embarazo. De las que dejaron de fumar completamente durante el embarazo, se mantenían abstinentes a los 6 meses el 36,4% de las mujeres del grupo de control y el 64,3% en el grupo de intervención (p = 0,002).ConclusionesEl consejo para dejar de fumar en la visita prenatal produce un aumento discreto en la proporción de abandonos, y una disminución significativa de las recaídas en el posparto.ObjectiveWomen´s tobacco consumption has increased in Spain in recent years, especially among women of reproductive age. This study aims to evaluate the impact of medical counselling integrated into pre-natal care on tobacco consumption during pregnancy and the period after delivery.DesignQuasi-experimental intervention study.SettingHospital del Mar, Barcelona.Patients219 patients who attended the Hospital del Mar for delivery during 1996 (control group) and 169 patients seen during their pregnancies at the same hospital in 1997 (intervention group).InterventionsThe control group patients had received normal care. The pregnant women in the intervention group received systematic structured counselling on giving up smoking, backed up by a special brochure composed for this purpose.Measurements and resultsThe intervention and control groups showed no statistically significant differences either in their social or demographic variables or in their tobacco consumption. In both groups the evolution of their smoking during pregnancy was determined during their pre-natal visits and six months after delivery through a telephone interview. 44 of the women in the control group (20.1%) gave up smoking before their first pre-natal visit, and 11 (5%) gave up during pregnancy. In the intervention group 26 (17.7%) had given up spontaneously and 16 (10.9%) gave up during pregnancy. Of those who gave up completely during pregnancy, 36.4% of women in the control group and 64.3% in the intervention group remained abstinent at six months (P=.002).ConclusionsCounselling at pre-natal checkups to give up smoking lightly increases the number of women who give up and reduces significantly the number of post-delivery backsliders

    Evaluación de la efectividad en salud pública: Fundamentos conceptuales y metodológicos

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    ResumenEn los últimos años ha aumentado de forma notable el interés por la evaluación de las intervenciones en salud, especialmente en relación a su utilidad social y su eficiencia económica. Sin embargo, todavía estamos lejos de tener un grado suficiente de consenso en los aspectos básicos de la evaluación, como son la terminología, la finalidad y la metodología de trabajo. En este marco se revisan las principales definiciones y clasificaciones de la evaluación aplicada a los programas y políticas en salud pública. En relación a la evaluación de resultados, se presentan los principales diseños evaluativos y sus componentes, y se revisan las amenazas a la validez interna de los resultados de los diseños evaluativos débiles. Se analizan y discuten las características de las intervenciones de salud pública que limitan las opciones de evaluación con diseños tradicionales. Entre estas limitaciones destacan la complejidad de las intervenciones, que habitualmente tienen múltiples componentes, y la dificultad de establecer un grupo de comparación sin intervención, en especial mediante asignación aleatoria. Para finalizar, se describe una propuesta de evaluación a partir de diseños evaluativos débiles, consistente en la valoración de la adecuación y la plausibilidad. La adecuación estaría determinada por la existencia de un cambio observable en los indicadores de resultados, y podría ser suficiente para tomar decisiones bajo determinadas condiciones; otras veces sería necesario analizar la plausibilidad, o atribución de los resultados observados al programa.AbstractIn the last few years, interest has markedly increased in evaluating health programs, especially their social utility and economic efficiency. However, consensus on key issues in evaluation, such as terminology, goals and methods is still a long way off. In this context, we review the main definitions and classifications of evaluation applied to public health programs and policies. We describe the main evaluation designs and their components, focusing on outcome evaluation. Threats to the internal validity of the results of weak evaluation designs are also discussed. The characteristics of public health interventions that limit evaluation with traditional designs are also analyzed. These limitations include the complexity of interventions, usually with multiple components, and the difficulty of forming an equivalent control group with no intervention, especially through random assignment. Finally, a two-step approach to evaluation through weak designs, which takes into account adequacy and plausibility, is described. Adequacy consists of the observation of a change in the selected indicators after the intervention, and would be sufficient to take decisions under certain conditions; at other times, plausibility would need to be analyzed, defined as attribution of the results to the program or intervention

    Adaptive control optimization in micro-milling of hardened steels-evaluation of optimization approaches

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    Nowadays, the miniaturization of many consumer products is extending the use of micro-milling operations with high-quality requirements. However, the impacts of cutting-tool wear on part dimensions, form and surface integrity are not negligible and part quality assurance for a minimum production cost is a challenging task. In fact, industrial practices usually set conservative cutting parameters and early cutting replacement policies in order to minimize the impact of cutting-tool wear on part quality. Although these practices may ensure part integrity, the production cost is far away to be minimized, especially in highly tool-consuming operations like mold and die micro-manufacturing. In this paper, an adaptive control optimization (ACO) system is proposed to estimate cutting-tool wear in terms of part quality and adapt the cutting conditions accordingly in order to minimize the production cost, ensuring quality specifications in hardened steel micro-parts. The ACO system is based on: (1) a monitoring sensor system composed of a dynamometer, (2) an estimation module with Artificial Neural Networks models, (3) an optimization module with evolutionary optimization algorithms, and (4) a CNC interface module. In order to operate in a nearly real-time basis and facilitate the implementation of the ACO system, different evolutionary optimization algorithms are evaluated such as particle swarm optimization (PSO), genetic algorithms (GA), and simulated annealing (SA) in terms of accuracy, precision, and robustness. The results for a given micro-milling operation showed that PSO algorithm performs better than GA and SA algorithms under computing time constraints. Furthermore, the implementation of the final ACO system reported a decrease in the production cost of 12.3 and 29 % in comparison with conservative and high-production strategies, respectively

    Study of additive manufacturing techniques to obtain tactile graphics

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    Ponència presentada a la 9th Manufacturing Engineering Society International Conference (MESIC 2021) 23rd-25th June 2021, Gijόn, SpainTactile graphics (TG) are intended to facilitate communication for people with total or partial visual impairment. For this purpose, TG include elements in relief that can be perceived through the sense of touch. TG can be fixed or portable. Fixed TG are expensive, as they are typically produced in very short runs, mostly single part production. Portable TG can be made by thermoforming polymer sheets, but a mould is still required, even though production runs are short (some tens). For this reason, the use of Rapid Manufacturing (RM) and Rapid Tooling (RT) strategies to manufacture TG can be of great interest. In this work, a literature review to study the application of Additive Manufacturing (AM) to obtain TG, both as RM and RT, is carried out. The review reveals the suitability of AM techniques to manufacture TG. In addition, some AM techniques are analysed to be used for a new type of TG, which is based on the deposition of glaze on ceramic tiles
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