990 research outputs found
El antropomorfismo como herramienta de divulgación científica por televisión: estudio de El Hombre y la Tierra
La tendencia del hombre al antropomorfismo resulta polémica al divulgar la ciencia, pero, ¿qué papel juega en su difusión? Los científicos intentan resolverlo desde mediados del s.XIX. A este interrogante se suma el de los profesionales de la comunicación, en particular, el de los documentalistas de la naturaleza que son quienes afrontan con frecuencia esta disyuntiva. Conocer qué opinan los académicos y realizadores permite ofrecer un posible acuerdo sobre la legitimidad del antropomorfismo para difundir la ciencia por televisión. Un convenio que se ejemplifica con el análisis de El Hombre y la Tierra: la serie documental de divulgación científica más exitosa en Españ
Caracterización de semillas blancas y negras de Salvia hispanica L. (Lamiaceae)
Caracterización de semillas blancas y negras de Salvia hispanica L. (Lamiaceae)Fil: Bueno, Mirian. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin
A hybrid ANN-GA model to prediction of bivariate binary responses: Application to joint prediction of occurrence of heart block and death in patients with myocardial infarction
Background: In medical studies, when the joint prediction about occurrence of two events should be anticipated, a statistical bivariate model is used. Due to the limitations of usual statistical models, other methods such as Artificial Neural Network (ANN) and hybrid models could be used. In this paper, we propose a hybrid Artificial Neural Network-Genetic Algorithm (ANN-GA) model to prediction the occurrence of heart block and death in myocardial infarction (MI) patients simultaneously. Methods: For fitting and comparing the models, 263 new patients with definite diagnosis of MI hospitalized in Cardiology Ward of Hajar Hospital, Shahrekord, Iran, from March, 2014 to March, 2016 were enrolled. Occurrence of heart block and death were employed as bivariate binary outcomes. Bivariate Logistic Regression (BLR), ANN and hybrid ANN-GA models were fitted to data. Prediction accuracy was used to compare the models. The codes were written in Matlab 2013a and Zelig package in R3.2.2. Results: The prediction accuracy of BLR, ANN and hybrid ANN-GA models was obtained 77.7%, 83.69% and 93.85% for the training and 78.48%, 84.81% and 96.2% for the test data, respectively. In both training and test data set, hybrid ANN-GA model had better accuracy. Conclusions: ANN model could be a suitable alternative for modeling and predicting bivariate binary responses when the presuppositions of statistical models are not met in actual data. In addition, using optimization methods, such as hybrid ANN-GA model, could improve precision of ANN model. © 2016, Health Hamadan University of Medical Sciences. All rights reserved
Reflexiones acerca de las compras públicas de diseño sostenible
El Estado tiene un importante poder de compra. Las contrataciones públicas son un gran potencial para promover y aplicar políticas públicas con objetivos sociales, ambientales, laborales y económicos. La sustentabilidad referida a esos contratos constituye una estrategia de gestión gubernamental que se enmarca en los principios constitucionales, en la medida que aquel constituye una herramienta efectiva para la satisfacción de las necesidades sociales. Por lo tanto, las contrataciones públicas sustentables deber estar dirigidas a adquirir bienes de diseño sustentable, innovadores, que sean amigables con el medio ambiente y que se ajusten a criterios de inclusión, de igualdad y de equidad social.The State has significant purchasing power. Public procurement is a great potential to promote and apply public policies that have social, environmental, labor and economic objectives. The sustainability referred to these contracts constitutes a government management strategy that is framed in constitutional principles, insofar as it constitutes an effective tool in the satisfaction of social needs. Therefore, sustainable public procurement should be aimed at acquiring goods of sustainable design, innovative, that are friendly to the environment and that conform to criteria of inclusion, equality and social equity.O Estado tem um poder de compra significativo. A contratação pública é um grande potencial para promover e aplicar políticas públicas que tenham objetivos sociais, ambientais, trabalhistas e econômicos. A sustentabilidade referida a estes contratos constitui uma estratégia de gestão governamental que se enquadra em princípios constitucionais, na medida em que constitui um instrumento eficaz na satisfação das necessidades sociais. Portanto, as compras públicas sustentáveis devem visar a aquisição de bens de design sustentável, inovadores, amigáveis ao meio ambiente e que atendam a critérios de inclusão, igualdade e equidade social
Bacterial enzymatic activity and bioavailability of heavy metals in sediments from Boa Viagem Beach (Guanabara Bay)
This study focuses on the quality of the organic matter that reaches the sediment from Boa Viagem Beach and through the evaluation of the total bacterial count, the electron transport system activity (ETSA), the esterase activity (EST), as well as the protein and the organic matter contents. Seasonal variations of organic matter, protein content and the number of bacteria were particularly notable in the summer. ETSA reached a maximum of 7.48 µl O2 h-1 g-1 in the summer. EST activity presented a different pattern once it reached a maximum of 0.17 µg fluorescein h-1 g-1 in the winter. The temporal variation of ETSA and EST activity indicated that biopolymers predominated in the winter, and oligomers or monomers predominated in the summer. These results suggest that organic carbon turnover is more likely to be controlled by organic matter quality. The heavy metals concentrations, especially for Cu, Zn, Ni and Cr, indicated absence of the inhibition of dehydrogenase activity, and they are not bioavailable in the EC50 valuesO trabalho enfoca a qualidade da matéria orgânica do sedimento da Praia da Boa Viagem, avaliando-se a contagem de bactérias, a atividade do sistema transportador de elétrons (ETSA), a atividade de esterases (EST) e a concentração de proteína e matéria orgânica. Variação sazonal de matéria orgânica, de proteína e número de bactérias foi significativo no verão. ETSA apresentou maior valor no verão, 7.48 µl O2 h-1 g-1. A EST foi maior no inverno, chegando a 0.17 µg fluorescein h-1 g-1. A variação temporal de ETSA e EST indicaram que biopolímeros predominaram no inverno e oligômeros e monômeros, no verão. Estes resultados sugerem que a transformação do carbono orgânico é controlado pela qualidade da matéria orgânica. As concentrações dos metais, especialmente Cu, Zn, Ni and Cr, indicam ausência de inibição da atividade das desidrogenase pois não estão biodisponíveis na concentração EC50
Assessing probabilistic reasoning in verbal-numerical and graphical-pictorial formats: An evaluation of the psychometric properties of an instrument
Research on the graphical facilitation of probabilistic reasoning has been characterised by the effort expended to identify valid assessment tools. The authors developed an assessment instrument to compare reasoning performances when problems were presented in verbal-numerical and graphical-pictorial formats. A sample of undergraduate psychology students (n=676) who had not developed statistical skills, solved problems requiring probabilistic reasoning. They attended universities in Spain (n=127; f=71.7%) and Italy (n=549; f=72.9%). In Italy 173 undergraduates solved these problems under time pressure. The remaining students solved the problems without time limits. Classical Test Theory (CTT) and Item Response Theory (IRT) were applied to assess the effect of two formats and to evaluate criterion and discriminant validity. The instrument showed acceptable psychometric properties, providing preliminary evidence of validity
High repetition rate and coherent Free-Electron Laser in the tender X-rays based on the Echo-Enabled Harmonic Generation of an Ultra-Violet Oscillator pulse
Fine time-resolved analysis of matter - i.e. spectroscopy and photon
scattering - in the linear response regime requires a fs-scale pulsed, high
repetition rate, fully coherent X-ray source. A seeded Free-Electron Laser
(FEL) driven by a Super-Conducting Linac, generating -
coherent photons at 2-5 keV with abou 0.5 MHz of repetition rate, can address
this need. The seeding scheme proposed is the Echo-Enabled Harmonic Generation,
alimented by a FEL Oscillator working at 13.6 nm with a cavity based on Mo-Si
mirrors. The whole chain of the X-ray generation is here described by means of
start-to-end simulations. Comparisons with the Self Amplified Spontaneus
Emission and a fresh-bunch harmonic cascade performed with similar electron
beams show the validity of this scheme
Who’s Got Your Mail?:Characterizing Mail Service Provider Usage
E-mail has long been a critical component of daily communication and the core medium for modern business correspondence. While traditionally e-mail service was provisioned and implemented independently by each Internet-connected organization, increasingly this function has been outsourced to third-party services. As with many pieces of key communications infrastructure, such centralization can bring both economies of scale and shared failure risk. In this paper, we investigate this issue empirically --- providing a large-scale measurement and analysis of modern Internet e-mail service provisioning. We develop a reliable methodology to better map domains to mail service providers. We then use this approach to document the dominant and increasing role played by a handful of mail service providers and hosting companies over the past four years. Finally, we briefly explore the extent to which nationality (and hence legal jurisdiction) plays a role in such mail provisioning decisions
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