489 research outputs found
Vapor-liquid surface tension of strong short-range Yukawa fluid
The thermodynamic properties of strong short-range attractive Yukawa fluids,
k=10, 9, 8, and 7, are determined by combining the slab technique with the
standard and the replica exchange Monte Carlo (REMC) methods. A good agreement
was found among the coexistence curves of these systems calculated by REMC and
those previously reported in the literature. However, REMC allows exploring the
coexistence at lower temperatures, where dynamics turns glassy. To obtain the
surface tension we employed, for both methods, a procedure that yields the
pressure tensor components for discontinuous potentials. The surface tension
results obtained by the standard MC and REMC techniques are in good agreement.Comment: 6 pages, 4 figure
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Efficiency and Environmental Factors in the US Electricity Transmission Industry
The electricity industry in most developed countries has been restructured over recent decades with the aim of improving both service quality and firms' performance. Regulated segments (e.g. transmission) still provide the infrastructure for the competitive segments and represent a notable amount of the total price paid by final customers. However there is a lack of empirical studies that analyze firms' performance in the electricity transmission sector. We conduct an empirical analysis of the US electricity transmission companies for the period 2001-2009. We use stochastic frontier models that allow us to identify determinants of firms' inefficiency and to control for weather conditions, potentially one of the most decisive uncontrollable factors in electricity transportation. Our results suggest that there is room for improvement in the performance of the US electricity transmission system. Regulators should also take into account that more adverse conditions generate higher levels of inefficiency and that achieving long-term efficiency improvements tends to deteriorate firms' short-term relative performance
Structural properties of fluids interacting via piece-wise constant potentials with a hard core
The structural properties of fluids whose molecules interact via potentials
with a hard core plus two piece-wise constant sections of different widths and
heights are presented. These follow from the more general development
previously introduced for potentials with a hard core plus piece-wise
constant sections [Condens. Matter Phys. {\bf 15}, 23602 (2012)] in which use
was made of a semi-analytic rational-function approximation method. The results
of illustrative cases comprising eight different combinations of wells and
shoulders are compared both with simulation data and with those that follow
from the numerical solution of the Percus-Yevick and hypernetted-chain integral
equations. It is found that the rational-function approximation generally
predicts a more accurate radial distribution function than the Percus-Yevick
theory and is comparable or even superior to the hypernetted-chain theory. This
superiority over both integral equation theories is lost, however, at high
densities, especially as the widths of the wells and/or the barriers increase.Comment: 10 pages, 11 figures; v2: Old Fig. 1 removed, new text on the
correlation length, 7 new references added, plus other minor change
In situ photoacoustic spectroscopy of phycobiliproteins in Gracilaria chilensis
peer reviewedPhycobiliproteins, the main polypeptidic components of the phycobilisomes (PBS), are biolog-
ical macromolecules arranged in complex interaction systems to perform light harvesting and conduction.
The optical properties of these systems can hardly be studied by conventional spectroscopic techniques.
Furthermore this techniques also involve laborious chemical extraction methods. Photoacoustic (PA) spec-
troscopy was successfully applied to an in situ study of the phycobiliproteins expression in the eukaryotic
red algae: Gracilaria chilensis
Planeamiento territorial sostenible: un reto para el futuro de nuestras sociedades; criterios aplicados
In a large part of the 17 sustainable development objectives set as goals for humanity by the UN, sustainability can be glimpsed. As a result of the dominant socio-productive model, the only way to head towards more sustainable territories that allow achieving and maintaining the well-being of the world's population is to bear in mind the need to properly plan territorial development. This work reflects on this need and takes a step forward in the definition of the main criteria to achieve territorial sustainability at regional and local scales
Steganography and watermarking on BMP images
In this work we perform some tests of steganography and watermarking on BMP images. We use the Discrete Cosine Transform (DCT) and Wavelets in order to insert information into high and medium frequencies. When steganography is used, we explain a method how to introduce secret data into an image and we show the capacity of the image to accept these data. For the watermarking technique we indicate where the data should be placed in order to achieve a robust insertion of the data even in the presence of image compression. Finally, we make a comparison between these two techniques
Comparing different models of the development of verb inflection in early child Spanish
How children acquire knowledge of verb inflection is a long-standing question in language acquisition research. In the present study, we test the predictions of some current constructivist and generativist accounts of the development of verb inflection by focusing on data from two Spanish-speaking children between the ages of 2;0 and 2;6. The constructivist claim that children's early knowledge of verb inflection is only partially productive is tested by comparing the average number of different inflections per verb in matched samples of child and adult speech. The generativist claim that children's early use of verb inflection is essentially error-free is tested by investigating the rate at which the children made subjectverb agreement errors in different parts of the present tense paradigm. Our results show: 1) that, although even adults ' use of verb inflection in Spanish tends to look somewhat lexically restricted, both children's use of verb inflection was significantly less flexible than that of their caregivers, and 2) that, although the rate at which the two children produced subjectverb agreement errors in their speech was very low, this overall error rate hid a consistent pattern of error in which error rates were substantially higher in low frequency than in high frequency contexts, and substantially higher for low frequency than for high frequency verbs. These results undermine the claim that children's use of verb inflection is fully productive from the earliest observable stages, and are consistent with the constructivist claim that knowledge of verb inflection develops only gradually
Increased adiposity appraised with cun-bae is highly predictive of incident hypertension. The sun project
Overweight and obesity are growing worldwide and strongly associated with hypertension. The Clínica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE) index is proposed as an optimal indicator of body fatness. We aimed to investigate the association of body fat as captured by the CUN-BAE index with incident hypertension in a Mediterranean population. We assessed 15,950 participants of the SUN (Seguimiento Universidad de Navarra) prospective cohort (63.7% women) initially free of hypertension. Participants completed follow-up questionnaires biennially. A validated 136-item food-frequency questionnaire was administered at baseline. We used Cox models adjusted for multiple confounders. Among 12.3 years of median follow-up (interquartile range: 8.3, 15.0 years), 2160 participants reported having received a diagnosis of hypertension. We observed a strong direct association between progressively higher the CUN-BAE index at baseline and incident hypertension during follow-up in multivariable-adjusted models for men and women, even after further adjustment for BMI ≥ 30 kg/m2, showing a significant association also in non-obese participants. For each 2-unit increase in the CUN-BAE index, hypertension risk increased by 27% and 29% in men and women, respectively. The results remained significant when considering longitudinal repeated measures of changes in body fat assessed with the CUN-BAE index among the different biennial follow-up questionnaires. Our results emphasize the importance of reducing and maintaining a low body fat to prevent hypertension
León (Spain) Health professionals’ knowledge and clinical practice towards the relationship between cardiovascular diseases and periodontal disease
Cardiovascular pathologies have a high prevalence in the geriatric population, with acute myocardial infarction being one of the main causes of death in Spain. These pathologies have a systemic inflammatory component that is of vital importance. We also know in dentistry that the main gingival pathogens are capable of generating a systemic inflammatory response, being indirectly involved in the development of the atherosclerotic lesion, assuming, therefore, that periodontal disease is a cardiovascular risk factor. The objective of this study is to determine the knowledge of health professionals who treat cardiovascular diseases about periodontal disease and its relationship with heart disease.A health survey was carried out on 100 Cardiologists, Internists and General Practitioners in the province of León. Points of interest in this survey: the professional’s own oral health, knowledge of the relationship between periodontal and heart disease and, lastly, the training received in medicine on oral health.60% of professionals reviewed their oral health annually and 20% randomly. 48% of health professionals were unaware of periodontal diseases, 77% claimed to have not received university training in this regard, only 13% of those surveyed acknowledged having received more than 10 hours of training on oral health in their experience and finally, 90% thought that training in both Medicine and Dentistry should be collaborative.The degree of knowledge of health professionals regarding oral health is poor (77%), therefore the number of collaborative consultations with dental professionals is low (<63%). Training projects targeting a correct preventive medicine are shown to be necessary
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