1,563 research outputs found
Primitive model electrolytes. A comparison of the HNC approximation for the activity coefficient with Monte Carlo data
Accuracy of the mean activity coefficient expression
(Hansen-Vieillefosse-Belloni equation), valid within the hypernetted chain
(HNC) approximation, was tested in a wide concentration range against new Monte
Carlo (MC) data for +1:-1 and +2:-2 primitive model electrolytes. The
expression has an advantage that the excess chemical potential can be obtained
directly, without invoking the time consuming Gibbs-Duhem calculation. We found
the HNC results for the mean activity coefficient to be in good agreement with
the machine calculations performed for the same model. In addition, the
thermodynamic consistency of the HNC approximation was tested. The mean
activity coefficients, calculated via the Gibbs-Duhem equation, seem to follow
the MC data slightly better than the Hansen-Vieillefosse-Belloni expression.
For completeness of the calculation, the HNC excess internal energies and
osmotic coefficients are also presented. These results are compared with the
calculations based on other theories commonly used to describe electrolyte
solutions, such as the mean spherical approximation, Pitzer's extension of the
Debye-H\"uckel theory, and the Debye-H\"uckel limiting law.Comment: 15 pages, 6 figure
Contrasting human perceptions of and attitudes towards two threatened small carnivores, Lycalopex fulvipes and Leopardus guigna, in rural communities adjacent to protected areas in Chile
Indexación: Scopus.The interaction between humans and small carnivores is a phenomenon especially frequent in rural fringes, as is the case of communities surrounding natural areas. In Chile, two species of threatened carnivores, the Darwin's Fox and the Guigna, have increased their contact with humans due to human-induced changes in their habitat. The objective of this study was to characterize the interactions of these species with humans by assessing human perceptions and attitudes toward them, and to assess livestock and poultry ownership and management practices in local communities to evaluate their possible roles in the phenomenon. We conducted semi-structured interviews in rural communities adjacent to natural protected areas of two different regions in southern Chile. We found that people have a more positive perception of Darwin's Foxes than Guignas, but both species are considered damaging due to poultry attacks. Livestock and poultry management was generally deficient. Improvements in animal management and education programs could lead to a significant decrease in negative interactions. © Sacristan et al. 2018.https://www.threatenedtaxa.org/index.php/JoTT/article/view/4030/442
Trombo intraventricular izquierdo en un gato con cardiomiopatía dilatada
Describimos el caso de un gato que presentaba un cuadro de disnea y derrame pleural, en el que tras realizar ecocardiografía se diagnosticó una cardiomiopatía dilatada (CMD), asociada a un trombo localizado dentro del ventrículo izquierdo. La localización habitual de estos trombos intracardiacos es el atrio izquierdo. El tromboembolismo es relativamente frecuente en gatos y ocurre principalmente como una complicación de enfermedades subyacentes. Los émbolos están mayoritariamente localizados en la aorta distal y en las arterias ilíacas.
Photon creation in a spherical oscillating cavity
We study the photon creation inside a perfectly conducting, spherical
oscillating cavity. The electromagnetic field inside the cavity is described by
means of two scalar fields which satisfy Dirichlet and (generalized) Neumann
boundary conditions. As a preliminary step, we analyze the dynamical Casimir
effect for both scalar fields. We then consider the full electromagnetic case.
The conservation of angular momentum of the electromagnetic field is also
discussed, showing that photons inside the cavity are created in singlet
states.Comment: 14 pages, no figure
Proposal and validation of a modified Simulated annealing algorithm for solving optimization problems
Durante las últimas décadas, los métodos de optimización heurísticos basados en imitar procesos naturales, biológicos, sociales o culturales a nivel computacional han despertado el interés de la comunidad científica debido a su capacidad para explorar eficientemente espacios de soluciones multimodales y multidimensionales. A pesar de todos los trabajos publicados en la literatura internacional, la mayoría de los algoritmos heurísticos todavía presentan baja precisión y exactitud. En este contexto, se propone y se valida un algoritmo Simulated annealing modificado (ASAM) para la solución de problemas de optimización. La evaluación del desempeño se realizó en funciones de pruebas (benchmark functions) con y sin restricciones reportadas en la literatura internacional y en problemas prácticos de diseño en ingeniería civil. En todos los casos analizados ASAM obtuvo iguales o mejores resultados que los reportados por otros autores, ilustrando la aplicabilidad del algoritmo propuesto.Over the last decades, heuristic optimization methods based on imitating natural, biological, social or cultural processes on a computational level have aroused the interest of the scientific community due to their ability to effectively explore multimodal and multidimensional solution spaces. Despite all the papers published in the international literature, most heuristic algorithms still have low precision and accuracy. In this context, a modified Simulated annealing algorithm (MSAA) is proposed and validated for solving optimization problems. Performance evaluation was performed on test functions (benchmark functions) with and without restrictions reported in the international literature and practical design problems in civil engineering. In all cases analyzed MSAA obtained equal or better results than those reported by other authors, illustrating the applicability of the proposed algorithm.Peer Reviewe
Heat pump for radiant cooled and heated floor driven by a microphotovoltaic system
This paper reports a solar trigeneration system installed at the Solar Energy Experimental Plant owned by the Spanish National Research Council (CSIC), located in Arganda del Rey,
20km east from Madrid.The authors want to express their gratitude to the Ministerio de Economía y Competitividad of Spain for funding the research project ENE2010-20650-CO2-01
Long-term assessment of the effectiveness of coastal protection regulations in conserving natural habitats in Spain
Spain has undergone rapid socioeconomic development in the past three decades. This has been linked to massive residential and infrastructural development based on a short-term, profitable and resource-intensive consuming model. As a result, large amounts of agricultural, natural and semi-natural soils have been lost to artificial areas, especially around main cities and on the coast. In this study, we assessed the effectiveness of the Spanish Shores Act at preventing land development in two biogeographical regions and three administrative scales between 1988 and 2020 using a BACI design and remote sensing data. We also analysed the combined effect of other regulations to prevent land development on the coast. The Shores Act was effective in reducing land development although moderate to substantial land development occurred in the zones affected by the Law, especially in the Mediterranean region. Adding other sectoral regulations to the Shores Act notably and consistently reduced land development across regions. Among them, cumulative protected area (PA) regulations were most effective in reducing coastal land development. The use of satellite images, especially Sentinel 2A MSI data within a BACI design, proved a useful method for assessing the effectiveness of fine-scale objectives of environmental policies such as the Shores Act.Funding for open access charge: Universidad de Málaga / CBU
Combination of DROOL rules and Protégé knowledge bases in the ONTO-H annotation tool
ONTO-H is a semi-automatic collaborative tool for the semantic annotation of documents, built as a Protégé 3.0 tab plug-in. Among its multiple functionalities aimed at easing the document annotation process, ONTO-H uses a rule-based system to create cascading annotations out from a single drag and drop operation from a part of a document into an already existing concept or instance of the domain ontology being used for annotation. It also gives support to the detection of name conflicts and instance duplications in the creation of the annotations. The rule system runs on top of the open source rule engine DROOLS and is connected to the domain ontology used for annotation by means of an ad-hoc programmed Java proxy
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