4,963 research outputs found

    Dissipative structures in optomechanical cavities

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    Motivated by the increasing interest in the properties of multimode optomechanical devices, here we study a system in which a driven mode of a large-area optical cavity is despersively coupled to a deformable mechanical element. Two different models naturally appear in such scenario, for which we predict the formation of periodic patterns, localized structures (cavity solitons), and domain walls, among other complex nonlinear phenomena. Further, we propose a realistic design based on intracavity membranes where our models can be studied experimentally. Apart from its relevance to the field of nonlinear optics, the results put forward here are a necessary step towards understanding the quantum properties of optomechanical systems in the multimode regime of both the optical and mechanical degrees of freedom.Comment: Updated version with a more general model and a specific implementation proposal. Comments and (constructive) criticism are welcom

    Complementarity, not optimization, is the language of markets

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    Each market agent (producer or consumer) in a power market pursues its own objective, typically to maximize its own profit. As such, the specific behavior of each agent in the market is conveniently formulated as a bi-level optimization problem whose upper-level problem represents the profit seeking behavior of the agent and whose lower-level problem represents the clearing of the market. The objective function and the constraints of this bi-level problem depend on the agent's own decision variables and on those of other agents as well. Understanding the outcomes of the market requires considering and solving jointly the interrelated bi-level problems of all market agents, which is beyond the purview of optimization. Solving jointly a set of bi-level (or single-level) optimization problems that are interrelated is the purview of complementarity. In this paper and in the context of power markets, we review complementarity using a tutorial approach

    Extraction of similarity based fuzzy rules from artificial neural networks

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    A method to extract a fuzzy rule based system from a trained artificial neural network for classification is presented. The fuzzy system obtained is equivalent to the corresponding neural network. In the antecedents of the fuzzy rules, it uses the similarity between the input datum and the weight vectors. This implies rules highly understandable. Thus, both the fuzzy system and a simple analysis of the weight vectors are enough to discern the hidden knowledge learnt by the neural network. Several classification problems are presented to illustrate this method of knowledge discovery by using artificial neural networks

    Contract design and supply chain coordination in the electricity industry.

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    In this article we propose a model of the supply chain in electricity markets with multiple generators and retailers and considering several market structures. We analyze how market design interacts with the different types of contract and market structure to affect the coordination between the different firms and the performance of the supply chain as a whole. We compare the implications on supply chain coordination and on the players’ profitability of two different market structures: a pool based market vs. bilateral contracts, taking into consideration the relationship between futures and spot markets. Furthermore, we analyze the use of contracts for differences and two-part-tariffs as tools for supply chain coordination. We have concluded that there are multiple equilibria in the supply chain contracts and structure and that the two-part tariff is the best contract to reduce double marginalization and increase efficiency in the management of the supply chain

    Effect of Sunflower and Marine Oils on Ruminal Microbiota, In vitro Fermentation and Digesta Fatty Acid Profile

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    Funding This work has been funded by Consejería de Educación, Junta de Castilla y León (research project LE007A07). Acknowledgments We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). Support received from CICYT project AGL2005-04760-C02-02 is gratefully acknowledged.Peer reviewedPublisher PD

    Anthropometric measures as predictive indicators of metabolic risk in a population of “holy week costaleros”

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    Preventive measures are a priority in those groups that perform intense physical efforts without physical preparation and that can also be overweight or obese. One of the groups that reflect these characteristics is the costaleros of the Holy Week of Andalusia, Spain. This paper aims to describe the effect of obesity on blood pressure. A descriptive cross-sectional study was conducted on 101 costaleros. The anthropometric measures were determined through segmental impedance. Cardiac recovery and anaerobic power were measured through the Ruffier–Dickson test and the Abalakov test, respectively. Blood pressure was measured when the individuals were at rest. The Kruskal–Wallis test was applied for of continuous parameters and the X2 test for dichotomous measures. Binary logistic regression models were used for the subsequent analysis with R-square and Receiver Operating Characteristic (ROC) curves. The average population was 28 years of age, 173.7 cm tall, and 82.59 Kg weigh. The excess of body fat was 11.27 Kg and Body Mass Index was 27.33 Kg/m2. 72.3% showed abnormal blood pressure and 68.2% were overweight. 32.7% had a waist-hip ratio higher than 0.94. The probability of presenting abnormal blood pressure was higher among the subjects whose fat content was higher and muscle content was lower

    Analyzing job satisfaction from a gender point of view: empirical application with logit and probit models

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    La influencia que las características individuales del personal de una empresa ejercen sobre su nivel de satisfacción laboral ha sido ampliamente analizada en la literatura al respecto, dedicando una especial atención a la variable edad pero también al género como un elemento determinante de los niveles de satisfacción de los recursos humanos. En numerosas investigaciones se constata que las mujeres presentan un nivel superior de satisfacción al de los varones. El presente trabajo analiza la influencia del género sobre la satisfacción laboral sobre una muestra de 1.804 personas empleadas en centros de enseñanza concertada en Andalucía, confirmando este resultado. Asimismo, se revisan las diferencias entre varones y mujeres respecto a la influencia de otras variables sociodemográficas, del puesto y de la organización sobre la satisfacción con el trabajo, detectando diferencias notables entre ambos sexos en algunos aspectos como el estado civil, el nivel educativo o la presencia o no en cargos directivosThe influence that the individual characteristics of the personnel of a company exercise on their level of job satisfaction has been largely analyzed in specialized literature, dedicating more attention to the age but also to the gender like a determining element of the levels of satisfaction on human resources. Numerous investigations verify the fact that women present a superior level of satisfaction to the one belonging to males. This paper examines the influence of the gender on job satisfaction on a sample of 1,804 people working in private educational centres in Andalusia, confirming this result. Furthermore, it revises the differences between men and women considering the influence over job satisfaction of other sociodemographic characteristics as well as variables about the job and the organization, detecting remarkable differences between both sexes in some aspects like the marital status, the educational level or the presence in managerial position
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