Dynamic Y-branched structures in quadratic nonlinear media

A selfsplitting of the beams entering a waveguide made of a quadratic nonlinear material is observed numerically. Relative π phase differences between harmonics as positively contributing to linear diffraction are shown to trigger the effect. Formation of solitons out of this energy so that a Y-branched structure is nonlinearly induced, is shown to be dependent on input and material parameters. Simple setups should provide the means for experimental observation of the predicted phenomena.Peer Reviewe

Conmutacion totalmente optica de ondas guiadas en medios virefring.

A new kind of tunable all-optical guided-wave thresholding device using waveguides consisting of both birefringent linear media and isotropic nonlinear media is discussed. The behavior of the lower threshold with a suitable orientation of the crystal optical axis of the birefringent substrate, relative to the direction of propagation, is analyzed for TE-dominant guided wavesPeer ReviewedPostprint (published version

Figure of merit for multiband antennas

This communication defines a figure of merit for multiband antennas that gives an objective quantification of the similarities between radiation patterns at the different antenna operating bands.Peer Reviewe

Square root module to combat dispersion-induced nonlinear distortion in Radio-over-Fiber Systems

Reduced dispersion-induced harmonics levels are reported for analogue radio-over-fiber systems by using a linearized receiver incorporating a memoryless electronic circuit with square root (SQRT)-like transfer function, and performing amplitude modulation (AM) at the transmitter. A practical implementation demonstrates the effectiveness of the AM-SQRT approach in linearizing the optical transmission system with respect to the conventional intensity modulation and direct detection system.Peer Reviewe

New modulation zero-shift method to characterize fast group delay ripple of dispersion-compensating fiber Bragg gratings

An upgrade to standard modulation phase-shift method is shown to improve accuracy through electrical scan of the optical spectrum. Experiments have allowed the capture of fast group delay ripple of a dispersion-compensating fiber Bragg grating with only a small modification to the standard setup.Peer Reviewe

Spatial walking solitons in quadratic nonlinear crystals

We investigate the properties of the families of spatial walking solitons propagating in planar waveguides made of quadratic nonlinear media under conditions for second-harmonic generation in the presence of Poynting vector walk-off. We study in detail the shape and various features of the solitons, their stability on propagation, and their excitation.Peer Reviewe

The AMBRE Project: searching for the closest solar siblings

Finding solar siblings, that is, stars that formed in the same cluster as the Sun, will yield information about the conditions at the Sun's birthplace. We search for solar sibling candidates in AMBRE, the very large spectra database of solar vicinity stars. Since the ages and chemical abundances of solar siblings are very similar to those of the Sun, we carried out a chemistry- and age-based search for solar sibling candidates. We used high-resolution spectra to derive precise stellar parameters and chemical abundances of the stars. We used these spectroscopic parameters together with Gaia DR2 astrometric data to derive stellar isochronal ages. Gaia data were also used to study the kinematics of the sibling candidates. From the about 17000 stars that are characterized within the AMBRE project, we first selected 55 stars whose metallicities are closest to the solar value (-0.1 < [Fe/H] < 0.1 dex). For these stars we derived precise chemical abundances of several iron-peak, alpha- and neutron-capture elements, based on which we selected 12 solar sibling candidates with average abundances and metallicities between -0.03 to 0.03 dex. Our further selection left us with 4 candidates with stellar ages that are compatible with the solar age within observational uncertainties. For the 2 of the hottest candidates, we derived the carbon isotopic ratios, which are compatible with the solar value. HD186302 is the most precisely characterized and probably the most probable candidate of our 4 best candidates. Very precise chemical characterization and age estimation is necessary to identify solar siblings. We propose that in addition to typical chemical tagging, the study of isotopic ratios can give further important information about the relation of sibling candidates with the Sun. Ideally, asteroseismic age determinations of the candidates could solve the problem of imprecise isochronal ages.Comment: Accepted for publication in A&

A 3D printed lens antenna for 5G applications

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A switchable multi-antenna architecture for lens-assisted beamsteering in the Ka-band region allocated for 5G communications (24-30 GHz) is proposed. The radiating elements are bow-tie antennas mounted with a 3D printed high-permittivity dielectric lens (e r = 10). A 5-element array is simulated showing switchable 30° beam steering over a 120° sector with 19 dB maximum gain. Single antenna measurements of a scaled prototype with a Polylactic Acid (PLA) lens (e r = 2.7) show gains around 11 dB, in agreement with projected performances.Peer ReviewedPostprint (author's final draft

Uptake and effectiveness of two-drug compared with three-drug antiretroviral regimens among HIV-positive individuals in Europe

Objective: To assess the use of two-drug antiretroviral regimens (2DR) and virologic and immunologic outcomes compared with three-drug regimens (3DR) in the EuroSIDA cohort. Design: Multicentre, prospective cohort study. Methods: Logistic regression was used to analyse the uptake and outcomes among HIV-positive individuals who started or switched to a 2DR compared with those on a 3DR. Virologic outcomes were assessed on-treatment as the proportion of individuals with controlled viral load (Peer reviewe

Pseudoartrosis congénita bilateral de la clavícula: a propósito de un caso familiar

Presentamos una paciente de nueve meses con pseudoartrosis congénita bilateral de ambas clavículas, cuya madre presenta el mismo cuadro. Dicho cuadro es una entidad rara, pobremente documentada en la ortopedia pediátrica. La etiología y patogenia aún permanece oscura. La apariencia clínico-radiológica consiste en la ausencia desde el nacimiento de un defecto de unión a nivel del tercio medio clavicular característico. El diagnóstico diferencial debe hacerse con las fracturas perinatales, pseudoartrosis postraumáticas y disostosis cleido-craneales.The case of a female patient of nine months of are and her mother, 41-year-old showing a Congenital Bilateral Pseudoarthrosis of the clavicle are presented. This is a rare entity that has been poorly documented in paediatrics orthopedics literature. The etiology and pathogenesis still remain unclear. The clinical and radiological appearance are characteristic. Differential diagnosis lies between postpartum fractures, postraumatic pseudoarthrosis, and cleidocraneal dysostosis