High-speed tunable photonic crystal fiber-based femtosecond soliton source without dispersion pre-compensation

We present a high-speed wavelength tunable photonic crystal fiber-based source capable of generating tunable femtosecond solitons in the infrared region. Through measurements and numerical simulation, we show that both the pulsewidth and the spectral width of the output pulses remain nearly constant over the entire tuning range from 860 to 1160 nm. This remarkable behavior is observed even when pump pulses are heavily chirped (7400 fs^2), which allows to avoid bulky compensation optics, or the use of another fiber, for dispersion compensation usually required by the tuning device.Comment: 8 pages, 11 figure

DG-JMCFIE-EFIE formulation for multi-material complex radiation problems

The versatility of the Discontinuous Galerkin (DG) method [1, 2] to accurately deal with non-conformal meshes makes it a well-suited approach to address complex, multi-scale problems, greatly simplifying computer-aideddesign (CAD) generation and meshing processes. It also facilitates the implementation of domain decomposition (DD) approaches, improving iterative convergence for challenging realistic problems where small geometrical details are combined with large-scale smooth structures [1, 3]. This work presents the combination of the electric current (J) and magnetic current (M) combined field integral equation (JMCFIE) [4] and the electric field integral equation (EFIE) with the DG approach, for the electromagnetic analysis of homogeneous and piecewise homogeneous objects, including perfect electric conductor (PEC) surfaces and dielectric interfaces. With this formulation, the interfaces between different materials can be modeled independently, without the need to attend to any constraint in the multi-region junctions between them. Furthermore, because the JMCFIE includes both tangential and normal (or twisted) equations for the electric and magnetic fields, it leads to a well-posed matrix system. Properly applying the interior penalty term described in [1], the rather complex treatment at multi-material junctions can be avoided. A novelty of this formulation is that it can address nonconformal junctions using DG between interfaces concerning different regions with different materials, including the combination of PEC and dielectric junctions, where the imposition of normal continuity across the junction becomes particularly tedious and critical for accurate antenna analysis [5]. We will show the details of the proposed formulation and discuss its capability to solve various realistic antenna cases during the presentation, demonstrating the versatility of this approach in the application of DG techniques for the design of complex dielectric and metamaterial antennas

Inverse sampling and triangular sequential designs to compare a small proportion with a reference value

Inverse sampling and formal sequential designs may prove useful in reducing the sample size in studies where a small population proportion p is compared with a hypothesized reference proportion p0. These methods are applied to the design of a cytogenetic study about chromosomal abnormalities in men with a daughter affected by Turner's syndrome. First it is shown how the calculated sample size for a classical design depends on the parameterization used. Later this sample size is compared with the required sample size in an inverse sampling design and a triangular sequential design using four different parameterizations (absolute differences, log-odds ratio, angular transform and Sprott's transform). The expected savings in sample size, when the alternative hypothesis is true, are 20% of the fixed sample size for the inverse sampling design and 40% for the triangular sequential design

From Broad-Spectrum Biocides to Quorum Sensing Disruptors and Mussel Repellents: Antifouling Profile of Alkyl Triphenylphosphonium Salts

30 páginas, 13 figuras, 4 tablas.-- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited‘Onium’ compounds, including ammonium and phosphonium salts, have been employed as antiseptics and disinfectants. These cationic biocides have been incorporated into multiple materials, principally to avoid bacterial attachment. In this work, we selected 20 alkyl-triphenylphosphonium salts, differing mainly in the length and functionalization of their alkyl chains, in fulfilment of two main objectives: 1) to provide a comprehensive evaluation of the antifouling profile of these molecules with relevant marine fouling organisms; and 2) to shed new light on their potential applications, beyond their classic use as broad-spectrum biocides. In this regard, we demonstrate for the first time that these compounds are also able to act as non-toxic quorum sensing disruptors in two different bacterial models (Chromobacterium violaceum and Vibrio harveyi) as well as repellents in the mussel Mytilus galloprovincialis. In addition, their inhibitory activity on a fouling-relevant enzymatic model (tyrosinase) is characterized. An analysis of the structure-activity relationships of these compounds for antifouling purposes is provided, which may result useful in the design of targeted antifouling solutions with these molecules. Altogether, the findings reported herein provide a different perspective on the biological activities of phosphonium compounds that is particularly focused on, but, as the reader will realize, is not limited to their use as antifouling agentsThis study was supported by the Spanish Ministry of Economy and Competitiveness (http:// www.mineco.gob.es/), SAF2011-28883-C03-01 (JJF), CTQ2011-28417-C02-01/BQU (VSM), AGL2010- 16464 (JMFB), MAT2013-40852-R (FL); Spanish Ministry of Education, Culture and Sport (http://www. mecd.gob.es/portada-mecd/), CEI 10/00018 (MN)Peer reviewe

On the domain decomposition method preconditioning of surface integral equation formulations solved by GMRES

In this communication, the performance of the generalized minimum residual method (GMRES) preconditioned by a domain decomposition method (DDM) scheme embedded in a surface integral equation (SIE) formulation is studied. In realistic large multiscale problems, the individual subdomain solutions, which in a DDM scheme acts as the preconditioners, have to be obtained by the Krylov subspace iterative processes with a decisive influence on the outcome of the overall iterative process that deals with subdomains’ mutual couplings. The convergence and accuracy of the global solution, as well as the degree of correlation between them, are studied for the left-, right-, and flexible-right-preconditioned GMRES to draw conclusions which maximize the efficiency in the application of the SIE-DDM implementation to challenging problems.Agencia Estatal de Investigación | Ref. PID2020-116627RB-C21Agencia Estatal de Investigación | Ref. PID2020-116627RB-C22Universidade de Vigo/CISU

Hybrid Monte Carlo algorithm for the double exchange model

The Hybrid Monte Carlo algorithm is adapted to the simulation of a system of classical degrees of freedom coupled to non self-interacting lattices fermions. The diagonalization of the Hamiltonian matrix is avoided by introducing a path-integral formulation of the problem, in d + 1 Euclidean space–time. A perfect action formulation allows to work on the continuum Euclidean time, without need for a Trotter–Suzuki extrapolation. To demonstrate the feasibility of the method we study the Double Exchange Model in three dimensions. The complexity of the algorithm grows only as the system volume, allowing to simulate in lattices as large as 163 on a personal computer. We conclude that the second order paramagnetic–ferromagnetic phase transition of Double Exchange Materials close to half-filling belongs to the Universality Class of the three-dimensional classical Heisenberg model

Monte Carlo determination of the phase diagram of the double-exchange model

We study the phase diagram of the double exchange model, with antiferromagnetic interactions, in a cubic lattice both at zero and finite temperature. There is a rich variety of magnetic phases, combined with regions where phase separation takes place. We identify phases, intrinsic to the cubic lattice, which are stable for realistic values of the interactions and dopings. Some of these phases break chiral symmetry, leading to unusual features