Dynamics of a self--gravitating magnetized source

We consider a magnetized degenerate gas of fermions as the matter source of a homogeneous but anisotropic Bianchi I spacetime with a Kasner--like metric. We examine the dynamics of this system by means of a qualitative and numerical study of Einstein-Maxwell field equations which reduce to a non--linear autonomous system. For all initial conditions and combinations of free parameters the gas evolves from an initial anisotropic singularity into an asymptotic state that is completely determined by a stable attractor. Depending on the initial conditions the anisotropic singularity is of the ``cigar'' or ``plate'' types.Comment: 7 pages, 1 figur

Rectification of electronic heat current by a hybrid thermal diode

We report the realization of an ultra-efficient low-temperature hybrid heat current rectifier, thermal counterpart of the well-known electric diode. Our design is based on a tunnel junction between two different elements: a normal metal and a superconducting island. Electronic heat current asymmetry in the structure arises from large mismatch between the thermal properties of these two. We demonstrate experimentally temperature differences exceeding $60$ mK between the forward and reverse thermal bias configurations. Our device offers a remarkably large heat rectification ratio up to $\sim 140$ and allows its prompt implementation in true solid-state thermal nanocircuits and general-purpose electronic applications requiring energy harvesting or thermal management and isolation at the nanoscale.Comment: 8 pages, 6 color figure

Quark stars and quantum-magnetically induced collapse

Quark matter is expected to exist in the interior of compact stellar objects as neutron stars or even the more exotic strange stars, based on the Bodmer-Witten conjecture. Bare strange quark stars and (normal) strange quark-matter stars, those possessing a baryon (electron-supported) crust, are hypothesized as good candidates to explain the properties of a set of peculiar stellar sources as the enigmatic X-ray source RX J1856.5-3754, some pulsars as PSR B1828-11 and PSR B1642-03, and the anomalous X-ray pulsars and soft gamma-ray repeaters. In the MIT bag model, quarks are treated as a degenerate Fermi gas confined to a region of space having a vacuum energy density $B_{bag}$ (the Bag constant). In this note, we modif{}y the MIT Bag Model by including the electromagnetic interaction. We also show that this version of the MIT model implies the anisotropy of the Bag pressure due to the presence of the magnetic field. The equations of state of degenerate quarks gases are studied in the presence of ultra strong magnetic fields. The behavior of a system made-up of quarks having (or not) anomalous magnetic moment is reviewed. A structural instability is found, which is related to the anisotropic nature of the pressures in this highly magnetized matter. The conditions for the collapse of this system are obtained and compared to a previous model of neutron stars build-up on a neutron gas having anomalous magnetic moment.Comment: 11 pages, 2 figure

Classical field theory on Lie algebroids: Variational aspects

The variational formalism for classical field theories is extended to the setting of Lie algebroids. Given a Lagrangian function we study the problem of finding critical points of the action functional when we restrict the fields to be morphisms of Lie algebroids. In addition to the standard case, our formalism includes as particular examples the case of systems with symmetry (covariant Euler-Poincare and Lagrange Poincare cases), Sigma models or Chern-Simons theories.Comment: Talk deliverd at the 9th International Conference on Differential Geometry and its Applications, Prague, September 2004. References adde

Sequence and Role in Virulence of the Three Plasmid Complement of the Model Tumor-Inducing Bacterium Pseudomonas savastanoi pv. savastanoi NCPPB 3335

Pseudomonas savastanoi pv. savastanoi NCPPB 3335 is a model for the study of the molecular basis of disease production and tumor formation in woody hosts, and its draft genome sequence has been recently obtained. Here we closed the sequence of the plasmid complement of this strain, composed of three circular molecules of 78,357 nt (pPsv48A), 45,220 nt (pPsv48B), and 42,103 nt (pPsv48C), all belonging to the pPT23A-like family of plasmids widely distributed in the P. syringae complex. A total of 152 coding sequences were predicted in the plasmid complement, of which 38 are hypothetical proteins and seven correspond to putative virulence genes. Plasmid pPsv48A contains an incomplete Type IVB secretion system, the type III secretion system (T3SS) effector gene hopAF1, gene ptz, involved in cytokinin biosynthesis, and three copies of a gene highly conserved in plant-associated proteobacteria, which is preceded by a hrp box motif. A complete Type IVA secretion system, a well conserved origin of transfer (oriT), and a homolog of the T3SS effector gene hopAO1 are present in pPsv48B, while pPsv48C contains a gene with significant homology to isopentenyl-diphosphate delta-isomerase, type 1. Several potential mobile elements were found on the three plasmids, including three types of MITE, a derivative of IS801, and a new transposon effector, ISPsy30. Although the replication regions of these three plasmids are phylogenetically closely related, their structure is diverse, suggesting that the plasmid architecture results from an active exchange of sequences. Artificial inoculations of olive plants with mutants cured of plasmids pPsv48A and pPsv48B showed that pPsv48A is necessary for full virulence and for the development of mature xylem vessels within the knots; we were unable to obtain mutants cured of pPsv48C, which contains five putative toxin-antitoxin genes

Chromomagnetic Dipole Moment of the Top Quark Revisited

We study the complete one-loop contributions to the chromagnetic dipole moment $\Delta\kappa$ of the top quark in the Standard Model, two Higgs doublet models, topcolor assited technicolor models (TC2), 331 models and extended models with a single extra dimension. We find that the SM predicts $\Delta\kappa = - 0.056$ and that the predictions of the other models are also consitent with the constraints imposed on $\Delta\kappa$ by low-energy precision measurements.Comment: 20 pages, 5 figures, Updat

Estudio teórico del ferromagnetismo en la superred (VN)1/(GaN)3

Using first principles calculations by means theLinearized Augmented Plane Wave (LAPW)method the structural, electronic and magneticproperties of (VN)1/(GaN)3 superlattice inwurtzite structure have been investigated. Theexchange and correlation effects were treatedusing the Generalized Gradient Approximation(GGA) with the Perdew, Burke and Ernzerhofparameterization (PBE). By total energycalculations it was found that ferromagneticstate (FM) is energetically more stable thannonmagnetic (NM) and antiferromagnetic (AFM)states. The ferromagnetism is presented althoughthat vanadium atom is not a magnetic atom. Inthe equilibrium volume, a total moment magneticof 2 μB/supercell was found in the ferromagneticstate. Also, it was found that the system possessesbehaviour electronic type half-metallic, whereconduction electrons conduction presents 100%of spin polarization in the Fermi level. This makesthis superlattice potentially useful for spin injectioninto ZnO or the same GaN.Usando métodos de primeros principios y basadosen la técnica de ondas planas aumentadas ylinealizadas (LAPW), se investigaron las propiedadesestructurales, electrónicas y magnéticas de lasuperred (VN)1/(GaN)3, en la fase wurtzita por serla configuración mas estable del GaN. Los efectosde intercambio y correlación se trataron empleandola Aproximación del Gradiente Generalizado(GGA), implementada en la parametrización dePerdew, Burke y Ernzerhof (PBE). A partir de loscálculos de la energía total, se encontró que el estadoferromagnético (FM) es enérgicamente más estable,comparado con los estados no-magnético (NM) yantiferromagnético (AFM). El ferromagnetismoocurre a pesar de que el átomo de vanadio no,es un átomo magnético en su fase natural. En elvolumen de equilibrio, el sistema en el estado delferromagnético, posee un momento magnéticototal de 2 μB por supercelda. Además, el cálculo de laestructura de bandas y densidad de estados, indicanque este sistema posee comportamiento electrónicotipo half-metallic, donde los electrones conducciónpresentan un 100% de polarización de espin en elnivel de Fermi. Este es un resultado importante puesla superred (VN)1/(GaN)3, puede ser potencialmenteútil en la fabricación de inyectores de espin a otrosmateriales como el ZnO o el mismo GaN

New insights into the molecular effects and probiotic properties of Lactobacillus pentosus pre-adapted to edible oils

In this study, the survival and growth of seven probiotic Lactobacillus pentosus strains isolated from Aloreña green table olives in the presence of vegetable-based edible oils (i.e., sunflower, olive, linseed, soy, corn, almond and argan) and mint essential oil were determined for the first time. Slight decreases in bacterial viability were observed depending on the strain and oil exposure, mainly mint essential oil. However, pre-adaptating the strains to the corresponding oils significantly increased their cell viabilities. As such, this study examined whether pre-adaptating probiotic L. pentosus strains with oils will constitute a new strategy to increase stress resistance, e.g., acids (pH 1.5) or bile (up to 3.6%) in food production and/or during digestion, and improve functional probiotic properties. Improvements in stress resistance (acidic and bile conditions) were noticed in some pre-adapted strains with oils; further, pre-adaptations with olive, argan, sunflower and linseed oils induced gene expression (e.g., fus, rpsL, pgm, groEL, enol and prep) for moonlighting proteins involved in several stress responses and other functions. As such, pre-adaptation with vegetable edible oils may represent a novel approach for manufacturing probiotic products by improving the stability of bacteria during industrial processes that would otherwise reduce their viability and functionality

Design and Multiphysics Analysis of Direct and Cross-Coupled SIW Combline Filters Using Electric and Magnetic Couplings

In this paper, combline substrate integrated waveguide (SIW) filters using electric and magnetic couplings are thoroughly studied. Thus, a negative coupling scheme consisting on an open-ended coplanar probe is proposed and analyzed in detail. Several in-line 3-pole filters at C-band are designed, manufactured and measured showing how the presented approach can be used for implementing direct couplings while enabling an important size reduction and improved spurious-free band compared to conventional magnetic irises. A fully-packaged quasi-elliptic 4-pole filter is also designed at 5.75 GHz showing how the negative coupling structure can be used for introducing transmission zeros by means of cross-couplings between non-adjacent resonators. Finally, average and peak power handling capabilities of these filters have been also analyzed from a multiphysics point of view. Measured results validate the theoretical predictions confirming that combline SIW filters can handle significant levels of continuous and peak power, providing at the same time easy integration, compact size and advanced filtering responses.This work was supported in part by MINECO (Spanish Government) under projects TEC2013-47037-C5-1-R and TEC2013-48036-C3-3-R. This paper is an expanded version from the IEEE MTT-S International Microwave Symposium, Phoenix, AZ, USA, May 17-22, 2015.Sirci, S.; Sánchez Soriano, MÁ.; Martínez Pérez, JD.; Boria Esbert, VE.; Gentili, F.; Boesch, W.; Sorrentino, R. (2015). Design and Multiphysics Analysis of Direct and Cross-Coupled SIW Combline Filters Using Electric and Magnetic Couplings. IEEE Transactions on Microwave Theory and Techniques. 63(12):4341-4354. doi:10.1109/TMTT.2015.2495287S43414354631