Simultaneous optical signal-to-noise ratio and differential group delay monitoring based on degree of polarization measurements in optical communications systems

We present a simultaneous optical signal-to-noise ratio (OSNR) and differential group delay (DGD) monitoring method based on degree of polarization (DOP) measurements in optical communications systems. For the first time in the literature (to our best knowledge), the proposed scheme is demonstrated to be able to independently and simultaneously extract OSNR and DGD values from the DOP measurements. This is possible because the OSNR is related to maximum DOP, while DGD is related to the ratio between the maximum and minimum values of DOP. We experimentally measured OSNR and DGD in the ranges from 10 to 30 dB and 0 to 90 ps for a 10 Gb/s non-return-to-zero signal. A theoretical analysis of DOP accuracy needed to measure low values of DGD and high OSNRs is carried out, showing that current polarimeter technology is capable of yielding an OSNR measurement within 1 dB accuracy, for OSNR values up to 34 dB, while DGD error is limited to 1.5% for DGD values above 10 ps. For the first time to our knowledge, the technique was demonstrated to accurately measure first-order polarization mode dispersion (PMD) in the presence of a high value of second-order PMD (as high as 2071 ps(2)). (C) 2012 Optical Society of America

Polarization switching in stretched pulse fiber laser

We studied experimentally polarization dynamics in a carbon nanotube mode locked stretched pulse fiber laser. For the first time, polarization locked, regular and irregular polarization switching have been observed at the microsecond time scale. © 2014 OSA.

Introduction à quelques aspects de quantification géométrique.

On révise les prérequis de géométrie différentielle nécessaires à une première approche de la théorie de la quantification géométrique, c'est-à-dire des notions de base en géométrie symplectique, des notions de groupes et d'algèbres de Lie, d'action d'un groupe de Lie, de G-fibré principal, de connexion, de fibré associé et de structure presque-complexe. Ceci mène à une étude plus approfondie des fibrés en droites hermitiens, dont une condition d'existence de fibré préquantique sur une variété symplectique. Avec ces outils en main, nous commençons ensuite l'étude de la quantification géométrique, étape par étape. Nous introduisons la théorie de la préquantification, i.e. la construction des opérateurs associés à des observables classiques et la construction d'un espace de Hilbert. Des problèmes majeurs font surface lors de l'application concrète de la préquantification : les opérateurs ne sont pas ceux attendus par la première quantification et l'espace de Hilbert formé est trop gros. Une première correction, la polarisation, élimine quelques problèmes, mais limite grandement l'ensemble des observables classiques que l'on peut quantifier. Ce mémoire n'est pas un survol complet de la quantification géométrique, et cela n'est pas son but. Il ne couvre ni la correction métaplectique, ni le noyau BKS. Il est un à-côté de lecture pour ceux qui s'introduisent à la quantification géométrique. D'une part, il introduit des concepts de géométrie différentielle pris pour acquis dans (Woodhouse [21]) et (Sniatycki [18]), i.e. G-fibrés principaux et fibrés associés. Enfin, il rajoute des détails à quelques preuves rapides données dans ces deux dernières références.

Análise tribológica das malhas multifuncionais obtidas por multicamadas

The present work consists in the analysis of tribologycal properties of basic and multifunctional knitted fabrics. This knowledge has fundamental importance for the textile industry since it can quantify, in an objective way, the tactil. The fabrics used were characterized by friction and mechanical tests for determining the viscoelastic region, wear resistance and friction coefficient of the fabrics used. The stress-strain curve was obtained by the method Kawabata, KES-FB1. Wear tests performed with the aid of equipment Martindale. The measurement of friction coefficient, two methods were used and analyzed comparatively. The first was a method already established worldwide known as KES-FB4 and the second was an innovative method called FRICTORQ, developed by the University of Minho. These two methods were compared taking into account the relative motion between the tribologycal pairs are different from each method. While the first motion is translational, the second is rotational. It was formal that the knitted had a multifunctional fabrics tribologycal performance which was better than the basic knitted fabrics, as the viscoelastic region, was laager highlighting a multifunctional structure, with greater wear resistance mainly on the back side of the knitted fabrics and lower friction coefficient. Performing a comparative analysis between two methods used to measure the friction coefficient, it was formal that both methods were consistent in terms of results. In operational terms, the FRICTORQ showed ease of operation and increased reproducibility of results

Apnea-like suppression of respiratory motion: First evaluation in radiotherapy.

BACKGROUND AND PURPOSE: Compensation for respiratory motion is needed while administering radiotherapy (RT) to tumors that are moving with respiration to reduce the amount of irradiated normal tissues and potentially decrease radiation-induced collateral damages. The purpose of this study was to test a new ventilation system designed to induce apnea-like suppression of respiratory motion and allow long enough breath hold durations to deliver complex RT. MATERIAL AND METHODS: The High Frequency Percussive Ventilation system was initially tested in a series of 10 volunteers and found to be well tolerated, allowing a median breath hold duration of 11.6min (range 3.9-16.5min). An evaluation of this system was subsequently performed in 4 patients eligible for adjuvant breast 3D conformal RT, for lung stereotactic body RT (SBRT), lung volumetric modulated arc therapy (VMAT), and VMAT for palliative pleural metastases. RESULTS: When compared to free breathing (FB) and maximal inspiration (MI) gating, this Percussion Assisted RT (PART) offered favorable dose distribution profiles in 3 out of the 4 patients tested. PART was applied in these 3 patients with good tolerance, without breaks during the "beam on time period" throughout the overall courses of RT. The mean duration of the apnea-like breath hold that was necessary for delivering all the RT fractions was 7.61min (SD=2.3). CONCLUSIONS: This first clinical implementation of PART was found to be feasible, tolerable and offers new opportunities in the field of RT for suppressing respiratory motion.

Second language influence on first language motion event encoding and categorization in Spanish-speaking children learning L2 English

Studies show cross-linguistic differences in motion event encoding, such that English speakers preferentially encode manner of motion more than Spanish speakers, who preferentially encode path of motion. Focusing on native Spanish speaking children (aged 5;00-9;00) learning L2 English, we studied path and manner verb preferences during descriptions of motion stimuli, and tested the linguistic relativity hypothesis by investigating categorization preferences in a non-verbal similarity judgement task of motion clip triads. Results revealed L2 influence on L1 motion event encoding, such that bilinguals used more manner verbs and fewer path verbs in their L1, under the influence of English. We found no effects of linguistic structure on non-verbal similarity judgements, and demonstrate for the first time effects of L2 on L1 lexicalization in child L2 learners in the domain of motion events. This pattern of verbal behaviour supports theories of bilingual semantic representation that postulate a merged lexico-semantic system in early bilinguals.

Orbital-polarization terms: From a phenomenological to a first-principles description of orbital magnetism in density-functional theory

Phenomenological orbital-polarizition (OP) terms have been repeatedly introduced in the single-particle equations of spin-density-functional theory, in order to improve the description of orbital magnetic moments in systems containing transition metal ions. Here we show that these ad hoc corrections can be interpreted as approximations to the exchange-correlation vector potential A(xc) of current-density functional theory (CDFT). This connection provides additional information on both approaches: phenomenological OP terms are connected to first-principles theory, leading to a rationale for their empirical success and a reassessment of their limitations and the approximations made in their derivation. Conversely, the connection of OP terms with CDFT leads to a set of simple approximations to the CDFT potential A(xc), with a number of desirable features that are absent from electron-gas-based functionals. (C) 2008 Wiley Periodicals, Inc.

Influence of detector motion in entanglement measurements with photons

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The von Mises-Fisher distribution of the first exit point from the hypersphere of the drifted Brownian motion and the density of the first exit time

A characterization is provided for the von Mises–Fisher random variable, in terms of first exit point from the unit hypersphere of the drifted Wiener process. Laplace transform formulae for the first exit time from the unit hypersphere of the drifted Wiener process are provided. Post representations in terms of Bell polynomials are provided for the densities of the first exit times from the circle and from the sphere.

In the council, regular session 1913-14 : Council Bill no. 255, introduced by Mr. Fletcher : first reading Oct 31, 1913; second reading Nov. 4, 1913; referred to Committee on Legislation : An ordinance [regarding motion pictures].

Bostwick, A.L. Censorship of motion picture films. Report to the City Council; p. 5-17.

First time measurements of polarization observables for the charged cascade hyperon in photoproduction

The parity violating weak decay of hyperons offers a valuable means of measuring their polarization, providing insight into the production of strange quarks and the matter they compose. Jefferson Lab's CLAS collaboration has utilized this property of hyperons, publishing the most precise polarization measurements for the Λ and Σ in both photoproduction and electroproduction to date. In contrast, cascades, which contain two strange quarks, can only be produced through indirect processes and as a result, exhibit low cross sections thus remaining experimentally elusive.^ At present, there are two aspects in cascade physics where progress has been minimal: characterizing their production mechanism, which lacks theoretical and experimental developments, and observation of the numerous excited cascade resonances that are required to exist by flavor SU(3) F symmetry. However, CLAS data were collected in 2008 with a luminosity of 68 pb−1 using a circularly polarized photon beam with energies up to 5.45 GeV, incident on a liquid hydrogen target. This dataset is, at present, the world's largest for meson photoproduction in its energy range and provides a unique opportunity to study cascade physics with polarization measurements.^ The current analysis explores hyperon production through the γ p → K+K +Ξ− reaction by providing the first ever determination of spin observables P, Cx and Cz for the cascade. Three of our primary goals are to test the only cascade photoproduction model in existence, examine the underlying processes that give rise to hyperon polarization, and to stimulate future theoretical developments while providing constraints for their parameters. Our research is part of a broader program to understand the production of strange quarks and hadrons with strangeness. The remainder of this document discusses the motivation behind such research, the method of data collection, details of their analysis, and the significance of our results.^

Proposição de um método de análise de movimentos de jogadores de tênis de campo a partir de vídeos televisivos = : Proposition of a method for tennis players motion analysis on broadcast videos

Universidade Estadual de Campinas . Faculdade de Educação Física