Structural defects in ion crystals by quenching the external potential: the inhomogeneous Kibble-Zurek mechanism

The non-equilibrium dynamics of an ion chain in a highly anisotropic trap is studied when the transverse trap frequency is quenched across the value at which the chain undergoes a continuous phase transition from a linear to a zigzag structure. Within Landau theory, an equation for the order parameter, corresponding to the transverse size of the zigzag structure, is determined when the vibrational motion is damped via laser cooling. The number of structural defects produced during a linear quench of the transverse trapping frequency is predicted and verified numerically. It is shown to obey the scaling predicted by the Kibble-Zurek mechanism, when extended to take into account the spatial inhomogeneities of the ion chain in a linear Paul trap.Comment: 5 pages, 3 figure

Integrate gender education in PhD curriculum studies: new pedagogical approaches.

Questions, aims & objectives: a mixed methods research. One of the most important mission of university is to incorporate the cultural and social changes in order to elaborate new reflections on didactics and research fields. The research is focused on how and why to integrate a gender education in PhD curriculum studies. The new idea has been listed among the priorities of intervention in the Horizon 2020

Turbocharged Solid Oxide Fuel Cell System: Design and Emulation

This paper presents a design model of a turbocharged solid oxide fuel cell system fueled by biogas. The aim of this plant layout is the development of a low-cost solution considering the coupling of the solid oxide fuel cell (SOFC) with a low-cost machine such as a turbocharger (instead of a microturbine). The whole system model calculates the operational conditions and realizes the coupling between the turbocharger, the recuperator and the solid oxide fuel cell system (comprising SOFC, air preheater, fuel compressor and pre-heater, reformer, off-gas burner and anodic ejector). This model also supports the design of an emulator test rig in which a burner, located inside a thermal insulated vessel, replaces the solid oxide fuel cell system. The emulator test rig will be useful to study the matching between the turbocharger and the fuel cell to validate simulation models, design innovative solutions and test the control system of the whole plant

Tachyon warm inflationary universe model in the weak dissipative regime

Warm inflationary universe model in a tachyon field theory is studied in the weak dissipative regime. We develop our model for an exponential potential and the dissipation parameter $\Gamma=\Gamma_0$=constant. We describe scalar and tensor perturbations for this scenario.Comment: 9 pages, accepted by European Physical Journal

An accelerated closed universe

We study a model in which a closed universe with dust and quintessence matter components may look like an accelerated flat Friedmann-Robertson-Walker (FRW) universe at low redshifts. Several quantities relevant to the model are expressed in terms of observed density parameters, $\Omega_M$ and $\Omega_{\Lambda}$, and of the associated density parameter $\Omega_Q$ related to the quintessence scalar field $Q$.Comment: 11 pages. For a festschrift honoring Alberto Garcia. To appear in Gen. Rel. Gra

Rangos de ciclicidad de la Formación Calizas de Aras de Alpuente (Albense superior-Cenomanense inferior) en el sector central de la Cordillera Ibérica

En los depósitos del Albense superior-Cenomanense medio del sector central de la Cordillera Ibérica, pueden diferenciarse cuatro impulsos transgresivos representados por cuatro mesosecuencias deposicionales, cuyos términos superiores más marinos dan lugar a cuatro miembros carbonatados. Dentro de cada una de estas mesosecuencias deposicionales es posible distinguir dos o más impulsos transgresivos menores que dan como resultado la presencia de secuencias deposicionales de rango inferior, hasta llegar a las secuencias sedimentarias métricas o decimétricas. De estos rangos de ciclicidad, los mayores tienen una tendencia transgresiva y pueden seguirse en una  extensión considerable de la cuenca sedimentaria. Por el contrario, el rango más pequeño de ciclicidad presenta una tendencia variable según los afloramientos

Directrices tectónicas durante la sedimentación del Cretácico medio en la zona central de la Cordillera Ibérica

La distribución de espesores y facies del Cretácico medio de la zona central de la Cordillera Ibérica, permiten identificar un conjunto de umbrales, surcos y escalones. Estos elementos paleogeográficos parecen corresponder con algunos de los elementos tectónicos de la estructura Alpina, segun la dirección principal ibérica, NW-SE, la dirección catalánide, NNE-SSW, la controvertida dirección E-W y en menor medida la dirección NE-SW. Algunos de estos hechos conducen a cuestionar el modelo de aulacdgeno propuesto, para la evolución post-hercínica del dominio de la Cordillera Ibéric

Curvature of the universe and the dark energy potential

The flatness of an accelerating universe model (characterized by a dark energy scalar field $\chi$) is mimicked from a curved model that is filled with, apart from the cold dark matter component, a quintessencelike scalar field $Q$. In this process, we characterize the original scalar potential $V(Q)$ and the mimicked scalar potential $V(\chi)$ associated to the scalar fields $Q$ and $\chi$, respectively. The parameters of the original model are fixed through the mimicked quantities that we relate to the present astronomical data, such that the equation state parameter $w_{_{\chi}}$ and the dark energy density parameter $\Omega_{\chi}$.Comment: References 7 and 8 have been corrected: (7) Riess et al. 1998, AJ, 116, 1009 and (8) Perlmutter et al. 1999, ApJ, 517, 56

Preservação de acessos de cucurbitáceas no Banco Ativo de Germoplasma (BAG) da Embrapa Semi-Árido - condicões atuais.

Como objetivo inicial testar a viabilidade do uso da sílico gel azul como dessecante em sementes de acessos previamente armazenados