1,138 research outputs found

    Vacuum decay in an interacting multiverse

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    We examine a new multiverse scenario in which the component universes interact. We focus our attention to the process of "true" vacuum nucleation in the false vacuum within one single element of the multiverse. It is shown that the interactions lead to a collective behaviour that might lead, under specific conditions, to a pre-inflationary phase and ensued distinguishable imprints in the comic microwave background radiation.Comment: 9 pages, 5 figure

    Classification of fold/hom and fold/Hopf spike-adding phenomena

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    The Hindmarsh-Rose neural model is widely accepted as an important prototype for fold/hom and fold/Hopf burstings. In this paper, we are interested in the mechanisms for the production of extra spikes in a burst, and we show the whole parametric panorama in an unified way. In the fold/hom case, two types are distinguished: a continuous one, where the bursting periodic orbit goes through bifurcations but persists along the whole process and a discontinuous one, where the transition is abrupt and happens after a sequence of chaotic events. In the former case, we speak about canard-induced spike-adding and in the second one, about chaos-induced spike-adding. For fold/Hopf bursting, a single (and continuous) mechanism is distinguished. Separately, all these mechanisms are presented, to some extent, in the literature. However, our full perspective allows us to construct a spike-adding map and, more significantly, to understand the dynamics exhibited when borders are crossed, that is, transitions between types of processes, a crucial point not previously studied. © 2021 Author(s)

    Determinants of profitability in Spanish financial institutions. Comparing aided and non-aided entities

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    The last financial crisis has led to the greatest contribution of public funds ever made to Spanish banks. This paper studies why the need for support has been asymmetric, with not all of the institutions requiring aid. Based on profitability of assets (ROA), we determine using panel data econometric and logit response models the components of profit and loss accounts that generated profitability as well as the factors leading to some entities to ask for aid. The analyses show that before the beginning of the crisis there were significant differences between entities that needed aid and those that did not. The most profitable banks grounded their success in the traditional revenue components of financial institutions (such as margin on interest rates and commissions), as well as in revenues obtained from participated companies and extraordinary results. The model offers a tool to detect entities in difficulties in advance, reducing the financial and social costs of public interventions. The factors more impacting on profitability of Spanish institutions are also identifie

    Decoherence in an accelerated universe

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    In this paper we study the decoherence processes of the semiclassical branches of an accelerated universe due to their interaction with a scalar field with given mass. We use a third quantization formalism to analyze the decoherence between two branches of a parent universe caused by their interaction with the vaccum fluctuations of the space-time, and with other parent unverses in a multiverse scenario.Comment: 11 pages, 2 figure

    Simultaneous determination of iron and copper using screen-printed carbon electrodes by adsorptive stripping voltammetry with o-phenanthroline.

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    The simultaneous voltammetric determination of iron and copper was accomplished by an unmodified screen-printed carbon electrode based on the complexation with o-phenanthroline assisted by the reducing agent ferrocyanide. The detection limits were 3.74 and 0.34 µg L−1 for iron and copper, respectively, and a linear response was observed from 12.5 to 400 µg L−1 for iron and from 1.14 to 400 µg L−1 for copper. This method successfully avoids interferences between iron and copper while allowing the simultaneous determination of both low and high metal concentrations usually found in the environment. Finally, a certified wastewater reference material was successfully analyzed, confirming the precision and accuracy of the proposed method

    Seguimiento de dependientes del alcohol y/o de la cocaína después de su salida de una Comunidad Terapéutica: estudio piloto

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    En España, las Comunidades Terapéuticas (CT) constituyen un modelo de tratamiento común en las adicciones, aunque apenas existe investigación acerca de su eficacia y la persistencia de sus logros. Objetivos: Evaluar los efectos a corto, medio y largo plazo del tratamiento de la adicción al alcohol o cocaína en las CT de la “Fundación Salud y Comunidad”. Diseño: Estudio piloto descriptivo, con un diseño secuencial de cohorte. Se aplicó una encuesta diseñada ad hoc a 91 usuarios para conocer su evolución en los diferentes periodos de seguimiento (1, 3, 5 ó 10 años después de su salida de la CT): variables sociodemográficas, de uso de la/s sustancia/s psicoactiva/s y relacionadas con la estancia en la CT. Se describe el cambio entre antes de la CT y en la actualidad respecto a variables académicas, laborales, de consumo de droga/s, salud, adaptación socio-familiar y comportamiento delictivo. Resultados: las cohortes mostraron un patrón previo relativamente común, recibiendo un tratamiento similar. Los usuarios afirman haber disminuido el hábito de consumo frecuente de la droga principal, encontrando un 48.9% que no ha recaído ni siquiera mediante un consumo ocasional de la/s droga/s. También perciben haber mejorado su salud y sus relaciones familiares, así como el comportamiento agresivo y problemas legales derivados del consumo de droga/s. Conclusiones: tras su rehabilitación en una CT, los usuarios manifiestan una disminución global del consumo de drogas y perciben una mejora a nivel de salud, familia, violencia y problemáticas derivadas del consumo

    Imine-palladacycles as phosphine-free precatalysts for low temperature Suzuki-Miyaura synthesis of nucleoside analogues in aqueous media

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    The synthesis and characterization of new water-soluble dinuclear palladacycles of the general formula [{Pd(R-C^N-SO3Na)(μ-AcO)}2] (R = H (1), OMe (2), Cl (3)) incorporating an ortho-metalated sodium 4-(N-benzylideneamino)benzenesulfonate moiety is reported. These complexes have been revealed to be excellent phosphine-free catalysts for the synthesis of functionalized nucleoside analogues involving a low-temperature Suzuki–Miyaura coupling of 5-iodo-2′-deoxyuridine with different arylboronic acids in neat water. The potential of 1–3 as synthetic precursors was also tested, and bridging acetates were cleaved by reaction with neutral PPh3, yielding the corresponding mononuclear derivatives [Pd(R-C^N-SO3Na)(AcO)(PPh3)] (R = H (4), MeO (5), Cl (6)). Analytical and spectroscopic techniques confirmed the proposed formulas and reactivities reported for complexes 1–6. Structural characterization by X-ray diffraction of single crystals grown from samples of 4 and 6 produced the unexpected but valuable crystallization-mediated compounds 4cm and 6cm that also supported the results presented here.This work has been partially supported by RTI2018-098233-B-C21 (MICINN) and 20790/PI/18 (Fundación SENECA CARM) grants. A.R.K would like to acknowledge SERB for EMR grant (EMR/2016/005439). Professor Gregorio Sánchez, who recently passed away, is gratefully acknowledged for his contribution to this work and his wise and continuous advise and suppor

    Surface-Parallel Sensor Orientation for Assessing Energy Balance Components on Mountain Slopes

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    The consistency of eddy-covariance measurements is often evaluated in terms of the degree of energy balance closure. Even over sloping terrain, instrumentation for measuring energy balance components is commonly installed horizontally, i.e. perpendicular to the geo-potential gradient. Subsequently, turbulent fluxes of sensible and latent heat are rotated perpendicular to the mean streamlines using tilt-correction algorithms. However, net radiation (Rn) and soil heat fluxes (G) are treated differently, and typically only Rn is corrected to account for slope. With an applied case study, we show and argue several advantages of installing sensors surface-parallel to measure surface-normal Rn and G. For a 17 % south-west-facing slope, our results show that horizontal installation results in hysteresis in the energy balance closure and errors of up to 25 %. Finally, we propose an approximation to estimate the surface-normal Rn, when only vertical Rn measurements are available.Andalusia Regional Government through projects P12RNM-2409Andalusia Regional Government through projects P10-RNM-6299Spanish Ministry of Economy and Competitiveness though projects CGL2010-18782, CGL2014-52838-C2-1-R (GEISpain) and CGL2013-45410-REuropean Community’s Seventh Framework Programme through INFRA-2010-1.1.16-262254 (ACTRIS),INFRA-2011-1-284274 (InGOS) and PEOPLE-2013-IOF-625988 (DIESEL) project

    Interacting universes and the cosmological constant

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    We study some collective phenomena that may happen in a multiverse scenario. First, it is posed an interaction scheme between universes whose evolution is dominated by a cosmological constant. As a result of the interaction, the value of the cosmological constant of one of the universes becomes very close to zero at the expense of an increasing value of the cosmological constant of the partner universe. Second, we found normal modes for a 'chain' of interacting universes. The energy spectrum of the multiverse, being this taken as a collective system, splits into a large number of levels, some of which correspond to a value of the cosmological constant very close to zero. We finally point out that the multiverse may be much more than the mere sum of its parts.Comment: 7 page
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