3D printing technique for the development of non-planar electromagnetic bandgap structures for antenna applications

The use of 3D printing for the development of non-planar electromagnetic bandgap (EBG) structures for antenna applications is proposed. A coplanar waveguide (CPW) fed antenna is tested on a non-planar EBG substrate, fabricated using additive manufacturing techniques. Inexpensive fuse filament fabrication is used as the fabrication process. Silver-loaded conducting ink is employed for the metallic components of the EBG. The CPW antenna on the non-planar EBG structure has a satisfactory reflection coefficient at 2.45 GHz, which is suitable for Bluetooth/WLAN communications. The radiation patterns have reduced back lobes and improved gain compared with the antenna in free space

Scalar and tensorial topological matter coupled to (2+1)-dimensional gravity:A.Classical theory and global charges

We consider the coupling of scalar topological matter to (2+1)-dimensional gravity. The matter fields consist of a 0-form scalar field and a 2-form tensor field. We carry out a canonical analysis of the classical theory, investigating its sectors and solutions. We show that the model admits both BTZ-like black-hole solutions and homogeneous/inhomogeneous FRW cosmological solutions.We also investigate the global charges associated with the model and show that the algebra of charges is the extension of the Kac-Moody algebra for the field-rigid gauge charges, and the Virasoro algebrafor the diffeomorphism charges. Finally, we show that the model can be written as a generalized Chern-Simons theory, opening the perspective for its formulation as a generalized higher gauge theory.Comment: 40 page

Wideband Metamaterial Crossed-Arm Unit Cell for the Design of Beam-Scanning Circularly Polarized Reflectarray Antenna

This paper presents a reconfigurable metamaterial unit cell using crossed arms and its application in designing a wideband beam-scanning circularly polarized (CP) reflectarray (RA) antenna. The unit cell is comprised of two pairs of reconfigurable rotated crossed-arms. One pair is connected by two line strips, and the other pair is connected by two arc-shaped strips. The unit cell is verified with a broad CP reflection bandwidth of 7.7-15.5 GHz. An equivalent circuit is utilized to illustrate its working principle for wide CP reflection bandwidth. Based on this meta material unit cell, a broadband RA antenna was designed, developed, and tested for the initial CP performance verification. A high gain of 26.3 dBic with the maximum aperture efficiency of 58.3 % is obtained for this fabricated RA antenna. In addition, a broad CP bandwidth (from 7.6 GHz to 15.9 GHz) for axial ratio <3 dB is achieved for the high gain unidirectional CP radiation

Hydrodynamic modelling and operational oceanography for oil-spill events in the andalusian coast: a real case study during the fedra accident (October 2008)

Peer Reviewe

Accelerated expansion of a universe containing a self-interacting Bose-Einstein gas

Acceleration of the universe is obtained from a model of non-relativistic particles with a short-range attractive interaction, at low enough temperature to produce a Bose-Einstein condensate. Conditions are derived for negative-pressure behavior. In particular, we show that a phantom-accelerated regime at the beginning of the universe solves the horizon problem, consistently with nucleosynthesis.Comment: 18 pages, 4 figure

Wideband Transmitarray Antenna Using Compact 2-Bit Filtering Unit Cells

A wideband transmitarray (TA) antenna using compact 2-bit filtering unit cells is presented with the center frequency designed at 10 GHz. The presented TA antenna features wide bandwidth with a compact aperture size, filtering radiation performance, and low cross-polarization levels. A novel compact 2-bit phasing scheme is first proposed and illustrated by utilizing the resonating characteristics of resonators. Charging and discharging principle of a resonator is utilized to realize a 180° phase shift, while J-invertor originating from the coupling between resonators is utilized to realize a 90° phase shift. Based on the proposed phasing scheme, novel 2-bit compact filtering unit cells are designed with a compact four-copper-layer configuration. Finally, a high-gain TA antenna was designed, fabricated, and measured for radiation performance verification. Owing to the elaborately designed unit cells and the cut-off effect of the feed horn, a filtering radiation performance with flat in-band gain and high out-of-band suppressions is obtained. Measured results show that a flat 3dB gain bandwidth of 21.3% is achieved with a thin thickness of 0.11λ 0 . High suppressions of 34.3 dB and 30.1 dB are measured over the lower and upper out-of-bands. In addition, a low cross-polarization level of -38.5 dB is obtained for high-quality wireless communications

Exploring the vicinity of the Bogomol'nyi-Prasad-Sommerfield bound

We investigate systems of real scalar fields in bidimensional spacetime, dealing with potentials that are small modifications of potentials that admit supersymmetric extensions. The modifications are controlled by a real parameter, which allows implementing a perturbation procedure when such parameter is small. The approach allows obtaining the energy and topological charge in closed forms, up to first order in the parameter. We illustrate the procedure with some examples. In particular, we show how to remove the degeneracy in energy for the one-field and the two-field solutions that appear in a model of two real scalar fields.Comment: Revtex, 9 pages, To be published in J. Phys.

T-cell intracellular antigens in health and disease

T-cell intracellular antigen 1 (TIA1) and TIA1-related/like protein (TIAR/TIAL1) are 2 proteins discovered in 1991 as components of cytotoxic T lymphocyte granules. They act in the nucleus as regulators of transcription and pre-mRNA splicing. In the cytoplasm, TIA1 and TIAR regulate and/or modulate the location, stability and/or translation of mRNAs. As knowledge of the different genes regulated by these proteins and the cellular/biological programs in which they are involved increases, it is evident that these antigens are key players in human physiology and pathology. This review will discuss the latest developments in the field, with physiopathological relevance, that point to novel roles for these regulators in the molecular and cell biology of higher eukaryotes.Ministry Economic Affairs and Competitiveness through FEDER funds (BFU2008–00354, BFU2011–29653 and BFU2014–57735-R). The CBMSO receives an institutional grant from Fundación Ramón Areces.Peer Reviewe

Fully relativistic calculation of magnetic properties of Fe, Co and Ni adclusters on Ag(100)

We present first principles calculations of the magnetic moments and magnetic anisotropy energies of small Fe, Co and Ni clusters on top of a Ag(100) surface as well as the exchange-coupling energy between two single adatoms of Fe or Co on Ag(100). The calculations are performed fully relativistically using the embedding technique within the Korringa-Kohn-Rostoker method. The magnetic anisotropy and the exchange-coupling energies are calculated by means of the force theorem. In the case of adatoms and dimers of iron and cobalt we obtain enhanced spin moments and, especially, unusually large orbital moments, while for nickel our calculations predict a complete absence of magnetism. For larger clusters, the magnitudes of the local moments of the atoms in the center of the cluster are very close to those calculated for the corresponding monolayers. Similar to the orbital moments, the contributions of the individual atoms to the magnetic anisotropy energy strongly depend on the position, hence, on the local environment of a particular atom within a given cluster. We find strong ferromagnetic coupling between two neighboring Fe or Co atoms and a rapid, oscillatory decay of the exchange-coupling energy with increasing distance between these two adatoms.Comment: 8 pages, ReVTeX + 4 figures (Encapsulated Postscript), submitted to PR

Extensions, expansions, Lie algebra cohomology and enlarged superspaces

After briefly reviewing the methods that allow us to derive consistently new Lie (super)algebras from given ones, we consider enlarged superspaces and superalgebras, their relevance and some possible applications.Comment: 9 pages. Invited talk delivered at the EU RTN Workshop, Copenhagen, Sep. 15-19 and at the Argonne Workshop on Branes and Generalized Dynamics, Oct. 20-24, 2003. Only change: wrong number of a reference correcte