6,032 research outputs found

    Non-radial pulsations in the Be/X binaries 4U0115+63 and SAXJ2103.5+4545

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    The discovery of non-radial pulsations (NRP) in the Be/X binaries of the Magellanic Clouds (MC, eg. Fabrycky 2005, Coe et al. 2005, Schmidtke & Cowley 2005) provided a new approach to understand these complex systems, and, at the same time, favoured the synergy between two different fields: stellar pulsations and X-ray binaries. This breakthrough was possible thanks to the MACHO and OGLE surveys. However, in our Galaxy, only two Be/X have been reported to show NRP: GROJ2058+42 (Kiziloglu et al. 2007) and LSI+61 235 (Sarty et al. 2009). Our objective is to study the short-term variability of Galactic Be/X binaries, compare them to the Be/X of the MC and to the isolated Galactic Be observed with CoRoT and Kepler. We present preliminary results of two Be/X stars, namely 4U0115+63 and SAXJ2103.5+4545 showing multiperiodicity and periodicity respectively, most probably produced by non-radial pulsations.Comment: 2 pages, 2 figures, IAUS 272 "Active OB stars: structure, evolution, mass loss and critical limits" conference, Paris, July 2010, submitte

    Oil Shocks and Monetary Policy in an Estimated DSGE Model for a Small Open Economy

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    This paper analyzes the effects of oil-price shocks from a general equilibrium standpoint. We develop a dynamic stochastic general equilibrium (DSGE) model, estimated by Bayesian methods for the Chilean economy. The model explicitly includes oil in the consumption basket and also in the technology used by domestic firms. With the estimated model we simulate how monetary policy and other variables would respond to an oil-price shock under the policy rule that best describes the behavior of the Central Bank of Chile (CBC). We also simulate the counterfactual responses in a flexible prices and wages equilibrium, and under alternative monetary frameworks. We show that a 13% increase in the real price of oil leads to a fall in output of about 0.5% and an increase in inflation of about 0.4%. The contractionary effect of the oil shock is mainly due to the endogenous tightening of the monetary policy.

    The Chilean Business Cycles Through the Lens of a Stochastic General Equilibrium Model

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    This paper uses an estimated dynamic stochastic general equilibrium model with nominal and real rigidities, to describe the sources of business cycle fluctuations in Chile. Our results show that foreign shocks and domestic supply shock account for a large share of output fluctuations over the last 20 years. Relatively tight domestic monetary conditions have contributed to contain inflationary pressures arising from other shocks, namely a slowdown in productivity by mid 90s. Foreign factors are also behind the large swings exhibited by the real exchange rate, although a monetary contraction in 1998 explains part of the delayed adjustment of the exchange rate in response to effects of the Asian crisis. The tight monetary policy around 1998 also contributes to the slow recovery of the employment afterwards.

    Invisibility and PT Symmetry: A Simple Geometrical Viewpoint

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    We give a simplified account of the properties of the transfer matrix for a complex one-dimensional potential, paying special attention to the particular instance of unidirectional invisibility. In appropriate variables, invisible potentials appear as performing null rotations, which lead to the helicity-gauge symmetry of massless particles. In hyperbolic geometry, this can be interpreted, via M\"{o}bius transformations, as parallel displacements, a geometric action that has no Euclidean analogy.Comment: 13 pages. No figure. Accepted for publication in Symmetr

    The role of the electrolyte on the SERS spectra of pyridine

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    SERS spectra of pyridine has been recorded on a silver electrode in a potential range from 0.0 to -1.20 V with a saline solution, pyridine / KCl (0.1M / 0.1M), by using the 514.5 nm exciting line by us [1]. Under these experimental conditions, the maximum intensity of the enhanced 8a and 9a bands is reached at -0.75 V and -1.20 V, respectively, being the 9a band what dominates the spectrum at negative electrode potential. Although this behavior has been explained under a resonant charge transfer mechanism, the nature of the electronic resonance processes involved in the enhancement of each band is different. The 8a band is enhanced due to an electronic excitation between the ground and excited charge transfer electronic state of the metal-adsorbate surface complex, while the activity of the 9a band is due to a plasmon-like excitation taking into account an overall electronic structure of small metal clusters [2] which is able to selectively modify the relative intensities of specific SERS band. We intend now to record pyridine SERS spectra under the same experimental conditions but varying only the type of electrolyte in order to check how it affects the relative intensities and vibrational wavenumbers of the bands as well as the electrode potential to which the enhanced bands reach the maximum intensity. Different electrolytes like KCl, NaCl, KBr, NaBr and Na2SO4, have been selected in such way that allows us to compare SERS spectra in which changes only the cation or the anion of the electrolyte. From the analysis of all these SERS spectra, it can be concluded that no significant wavenumbers shifts have been detected, while the relative intensities of the bands and the electrode potential to which the maximum intensity is reached are slightly modified. NaBr electrolyte requieres more negative electrode potential in order to enhance the 8a and 9a bands and to resolve the 12 and 1 pair. Acknowledgements We are grateful to the Spanish MINECO (CTQ2012-31846) and Junta de Andalucía (FQM-5156 and 6778), for financial support. References [1] J.F. Arenas, I. López Tocón, J.C. Otero, and J.I. Marcos, J. Phys. Chem. 100, 9254-9261 (1996). [2] J. Román-Pérez, I. López-Tocón, J.L. Castro, J. F. Arenas, J. Soto and J.C. Otero, Phys. Chem. Chem. Phys.17, 2326-2329 (2015).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Psicología social ¿para qué?

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    Doing research involves a minimum set of responsibilities. One of the is to ask why do research? Today researches and students do not ask about it. They assume they have to do research as mandatory. Research becomes a means and not and end. This paper is an overview of social psychology in Mexico (some statistical data is provided). It shows three aspects of how social psychology is addressed and some critical reflections that could be useful for those engaged in research in social psychology.Hacer investigación implica un conjunto de responsabilidades mínimas. Una de ellas es preguntarse ¿para qué hacer investigación? En el mundo actual los investigadores y los estudiantes no suelen preguntárselo. Suponen que deben hacer investigación como una obligación. Esto hace que la investigación se convierta en un medio y no en un fin. En este texto se brinda un panorama general de la psicología social en México recurriendo a algunos datos estadísticos. Posteriormente se abordan tres aspectos de la forma en que se hace psicología social y se ofrecen algunas reflexiones críticas que podrían ser útiles para quienes se dedican a la investigación en psicología social

    Psicología Social

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    Las historias románticamente grandes cuentan con tres elementos: dragón, princesa y caballero, que vistos de otra forma son la maldad, la bondad y la valentía, en conjunto, como unidad, no como elementos aislados. Al romance no se le podría encontrar nunca en el lloriqueo de la princesa que ha sido aislada en una torre del castillo o robada por el dragón. Tampoco puede encontrársele en la desesperación del caballero que agiganta el paso con la única finalidad de rescatar a su doncella

    A recoverable production planning model

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    Aware of the importance of developing new alternatives to improve the performance of the companies, our purpose in this paper is to develop a medium term production planning model that deals with the concepts of Partnership and Reverse Logistics. Our model takes advantage of the synergies of integration, developing a model for global production planning that generates the optimal production and purchasing schedule for all the companies integrating a logistic chain. In a second part of the paper we incorporate products returns to the first model proposed, and analyze the implications they have over this model. We use some examples with different configurations of supply chains varying the number of production plants, distribution centers and recovery plants. To solve the model we have combined optimization and simulation procedures.Reverse logistics, production planning, remanufacturing, returns, supply chain management, simulation, optimization

    Prehistoric psychotropic consumption in Andean Chilean mummies

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    Hallucinogenic plants are often regarded as the main source of psychoactive drugs in antiquity to reach deep altered states of consciousness^1,2^. Many researchers believe this was particularly true during the Tiwanaku empire expansion, circa (500-1000 A.D.), along the Atacama Desert of Chile. Highly decorated snuffing tablets and tubes are often found as grave goods during this period^3,4,5,6,7,8^. Until now the type of drugs consumed in this paraphernalia has been unclear. From the modern city of Arica, naturally mummified human bodies with abundant hair provided a unique opportunity to test for hallucinogenic plants consumed in Andean prehistory. Analysis by gas chromatography and mass spectrometry demonstrated the presence of harmine. The Banisteriopsis vine, commonly called Ayahuasca, was the probable source. This is the first confirmed evidence of psychoactive plant consumption in pre-Hispanic Andean populations along the Atacama coastal region. Of the 32 mummy hair samples analyzed 3 males tested positive for harmine. This alkaloid aids in the catalysis and synergic effects of powerful hallucinogenic drugs. The consumption of harmine was likely related to medicinal practices and not exclusively ingested by shamans. Another important aspect of this evidence is that Banisteriopsis is an Amazon plant. It does not grow in the Atacama coastal region. Thus, our findings reveal extensive plant trade networks in antiquity between the coast, desert, highlands, and Amazon basin. The excellent preservation of human organic specimens, the use of gas chromatography and mass spectrometry allowed us to map and demonstrate the consumption of psychoactive compound plants in Andean prehistory. In addition, our findings open the door for future studies to debate the consumption and social role of ancient psychoactive and hallucinogenic plants

    Tres Principios para la Configuración de una Psicología de lo Complejo

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    The dialogical principle, the organizational recursivity principle and the hologramatical principle, are the three principles can help us to think the complexity. The first one allows us to think how the duality can stay in the breast of the unit. The second lead us to the understanding of how the products and the effects are, at the same time, causes and products of what produces them. The third, and perhaps the most beautiful of three, refers that the part itself is not only in the everything but rather the everything is also in the part. Three images can help us to clarify these principles: first, the process of mating of the hens produces hens, which produces the process of mating of the hens; second, the hens put eggs of where to come out more hens than put more eggs; third, a hen egg is a hen in potential. The configuration of a psychology of complexity is related with the application of this principles for the analysis of the social reality in several addresses: a) to win complexity in the explanatory and descriptive environments, opening diverse ways of thinking and novel investigation lines, accepting that the theories of the complexity have been related inevitably with the sciences of the behavior; b) to understand that the daily life can be studied from four optics that deserve recognition in the epistemological level of the social psychology: fuzzyness, catastrophic, fractal and chaotic; c) to recognize that reality demands scientific explanations complex and leave the simplicity; d) to renovate the psychology from their base and not from the obedience and the academic subjection
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