Coupling matrix filter synthesis based on reflection matrices

© 2015 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.The paper introduces the concept of reflection matrices in the coupling matrix filter reconfiguration. It is shown that reflection matrices are complementary to rotation matrices a useful concept that can be used alternatively to rotation matrices in the similarity transformations that are applied in order to transform the coupling matrix to a suitable form. A cross-coupled filter example is given where both concepts are used.This work has been founded by SIWTUNE Marie Curie CIG no 322162 and DGCYT MTM2012-33073 grants.Müller, A.; Favennec, J.; Sanabria-Codesal, E. (2015). Coupling matrix filter synthesis based on reflection matrices. IEEE. https://doi.org/10.1109/APMC.2015.741179

On the sum of the transmission and reflection coefficient on the Smith chart and 3D Smith chart

© 2015 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.The paper presents in premiere a simple mapping property of the sum of the reflection and transmission parameters of reciprocal two port networks. It is proved that although the reflection and transmission parameter may have very complicated paths on the Smith chart, their sum will be always moving on the unit circle if the circuit is symmetric and lossless. Further once symmetrical losses at the ports occur their sum path will switch on a family of circles through one point. Using inversive geometry we construct a new function which maps this family of circles in lines on the extended Smith chart. The proposed method for checking the symmetry uses just two parameters and avoids testing the phase of the corresponding input and output parameters. By means of the 3D Smith chart we propose in the end an alternative approach to visualize the parameters.This work has been founded by SIWTUNE Marie Curie CIG no 322162, POSDRU/159/1.5/S/134398 and DGCYT MTM2012-33073 grants.Müller, A.; Sanabria-Codesal, E.; Moldoveanu, A.; Asavei, V.; Favennec, J. (2015). On the sum of the transmission and reflection coefficient on the Smith chart and 3D Smith chart. IEEE. https://doi.org/10.1109/APMC.2015.7411635

Phase control of La2CuO4 in thin-film synthesis

The lanthanum copper oxide, La2CuO4, which is an end member of the prototype high-Tc superconductors (La,Sr)2CuO4 and (La,Ba)2CuO4, crystallizes in the "K2NiF4" structure in high-temperature bulk synthesis. The crystal chemistry, however, predicts that La2CuO4 is at the borderline of the K2NiF4 stability and that it can crystallize in the Nd2CuO4 structure at low synthesis temperatures. In this article we demonstrate that low-temperature thin-film synthesis actually crystallizes La2CuO4 in the Nd2CuO4 structure. We also show that the phase control of "K2NiF4"-type La2CuO4 versus "Nd2CuO4"-type La2CuO4 can be achieved by varying the synthesis temperature and using different substrates.Comment: 4 pages, 5 figures, submitted to PRB, revte

Improving Maternal Mental Health Following Preterm Birth Using an Expressive Writing Intervention: A Randomized Controlled Trial.

Evaluations of evidence-based, easily accessible, psychological interventions to improve maternal mental health following very preterm birth are scarce. This study investigated the efficacy and acceptability of the expressive writing paradigm for mothers of very preterm infants. The level of maternal posttraumatic stress and depressive symptoms was the primary outcome. Participants were 67 mothers of very preterm babies who were randomly allocated into the intervention (expressive writing; n = 33) or control group (treatment-as-usual; n = 32) when their infant was aged 3 months (corrected age, CA). Measurements were taken at 3 months (pre-intervention), 4 months (post-intervention), and 6 months CA (follow-up). Results showed reduced maternal posttraumatic stress (d = 0.42), depressive symptoms (d = 0.67), and an improved mental health status (d = 1.20) in the intervention group, which were maintained at follow-up. Expressive writing is a brief, cost-effective, and acceptable therapeutic approach that could be offered as part of the NICU care

New Physics and CP Violation in Hyperon Nonleptonic Decays

The sum of the CP-violating asymmetries A(Lambda_-^0) and A(Xi_-^-) in hyperon nonleptonic decays is presently being measured by the E871 experiment. We evaluate contributions to the asymmetries induced by chromomagnetic-penguin operators, whose coefficients can be enhanced in certain models of new physics. Incorporating recent information on the strong phases in Xi->Lambda pi decay, we show that new-physics contributions to the two asymmetries can be comparable. We explore how the upcoming results of E871 may constrain the coefficients of the operators. We find that its preliminary measurement is already better than the epsilon parameter of K-Kbar mixing in bounding the parity-conserving contributions.Comment: 12 pages, 2 figure

Repulsion and attraction in high Tc superconductors

The influence of repulsion and attraction in high-Tc superconductors to the gap functions is studied. A systematic method is proposed to compute the gap functions using the irreducible representations of the point group. It is found that a pure s-wave superconductivity exists only at very low temperatures, and attractive potentials on the near shells significantly expand the gap functions and increase significantly the critical temperature of superconductivity. A strong on-site repulsion drives the $A_{1g}$ gap into a $B_{1g}$ gap. It is expected that superconductivity with the $A_{1g}$ symmetry reaches a high critical temperature due to the cooperation of the on-site and the next-nearest neighbor attractions.Comment: 4 pages, 5figure

Supporting collaborative improvement of resources in the Khresmoi health information system

Since medical knowledge relies on both scientific knowledge and real-life experience, the importance of user contributions to improve resources in health systems cannot be underestimated. We present work from the Khresmoi project which aims to develop a multilingual multimodal search and access system for biomedical information and documents. Khresmoi targets three distinct user classes with differing levels of medical knowledge and information requirements, namely: general public, general practitioners, and, as an example of an area of clinical expertise, radiologists. The Khresmoi system will provide these users with valuable (whose quality has been evaluated and approved) and enriched (meta information from biomedical knowledge bases is added) medical information, selected to fit their medical knowledge and their preferred language. The system will include novel collaborative components of the system are designed to provide means for users to contribute to the system’s knowledge by adding or correcting annotations to the documents, as well as a collaborative platform where they will be able to share their own files and both annotate and discuss them

User-centered Development of a Clinical Decision Support System

Scientific progress is offering increasingly better ways to tailor a patient’s treatment to the patient’s needs, i.e., better support for optimal clinical decision-making can be offered. Choosing the appropriate treatment for a patient depends on numerous factors, including pathology results, tumor stage, genetic, and molecular characteristics. Bayesian networks are a type of probabilistic artificial intelligence, which in principle would be suitable to support complex clinical decision-making. However, most clinicians do not have experience with these networks. This paper describes an approach of developing a clinical decision support system based on Bayesian networks, that does not require insight knowledge about the underlying computational model for its use. It is developed as a therapy-oriented approach with a focus on usability and explainability. The approach features the computation and presentation of individualized treatment recommendations, comparison of treatments and patient cases, as well as explanations and visualizations providing additional information on the current patient case

Diffusive spin transport

Information to be stored and transported requires physical carriers. The quantum bit of information (qubit) can for instance be realised as the spin 1/2 degree of freedom of a massive particle like an electron or as the spin 1 polarisation of a massless photon. In this lecture, I first use irreducible representations of the rotation group to characterise the spin dynamics in a least redundant manner. Specifically, I describe the decoherence dynamics of an arbitrary spin S coupled to a randomly fluctuating magnetic field in the Liouville space formalism. Secondly, I discuss the diffusive dynamics of the particle's position in space due to the presence of randomly placed impurities. Combining these two dynamics yields a coherent, unified picture of diffusive spin transport, as applicable to mesoscopic electronic devices or photons propagating in cold atomic clouds.Comment: Lecture notes, published in A. Buchleitner, C. Viviescas, and M. Tiersch (Eds.), "Entanglement and Decoherence. Foundations and Modern Trends", Lecture Notes in Physics 768, Springer, Berlin (2009

Universality of Level Spacing Distributions in Classical Chaos

We suggest that random matrix theory applied to a classical action matrix can be used in classical physics to distinguish chaotic from non-chaotic behavior. We consider the 2-D stadium billiard system as well as the 2-D anharmonic and harmonic oscillator. By unfolding of the spectrum of such matrix we compute the level spacing distribution, the spectral auto-correlation and spectral rigidity. We observe Poissonian behavior in the integrable case and Wignerian behavior in the chaotic case. We present numerical evidence that the action matrix of the stadium billiard displays GOE behavior and give an explanation for it. The findings present evidence for universality of level fluctuations - known from quantum chaos - also to hold in classical physics