On the Relation between Discrete and Continuous-time Refined Instrumental Variable Methods

The Refined Instrumental Variable method for discrete-time systems (RIV) and its variant for continuous-time systems (RIVC) are popular methods for the identification of linear systems in open-loop. The continuous-time equivalent of the transfer function estimate given by the RIV method is commonly used as an initialization point for the RIVC estimator. In this letter, we prove that these estimators share the same converging points for finite sample size when the continuous-time model has relative degree zero or one. This relation does not hold for higher relative degrees. Then, we propose a modification of the RIV method whose continuous-time equivalent is equal to the RIVC estimator for any non-negative relative degree. The implications of the theoretical results are illustrated via a simulation example.</p

Parametric Continuous-Time Blind System Identification

In this paper, the blind system identification problem for continuous-time systems is considered. A direct continuous-time estimator is proposed by utilising a state-variable-filter least squares approach. In the proposed method, coupled terms between the numerator polynomial of the system and input parameters appear in the parameter vector which are subsequently separated using a rank-1 approximation. An algorithm is then provided for the direct identification of a single-input single-output linear time-invariant continuous-time system which is shown to satisfy the property of correctness under some mild conditions. Monte Carlo simulations demonstrate the performance of the algorithm and verify that a model and input signal can be estimated to a proportion of their true values

A case–control study to assess the effectiveness of pertussis vaccination during pregnancy on newborns, Valencian community, Spain, 1 March 2015 to 29 February 2016

In the Valencian Community (Spain), the programme of maternal pertussis vaccination during pregnancy started in January 2015. The objective of this study was to estimate in this region the vaccine effectiveness (VE) in protecting newborns against laboratory-confirmed pertussis infection. A matched case–control study was undertaken in the period between 1 March 2015 and 29 February 2016. Twenty-two cases and 66 controls (+/− 15 days of age difference) were included in the study. Cases were non-vaccinated infants < 3 months of age at disease onset testing positive for pertussis by real-time PCR. For every case three unvaccinated controls were selected. Odds ratios (OR) were calculated by multiple conditional logistic regression for association between maternal vaccination and infant pertussis. Other children in the household, as well as mother- and environmental covariates were taken into account. The VE was calculated as 1 − OR. Mothers of five cases (23%) and of 41 controls (62%) were vaccinated during pregnancy. The adjusted VE was 90.9% (95% confidence interval (CI): 56.6 to 98.1). The only covariate in the final model was breastfeeding (protective effect). Our study provides evidence in favour of pertussis vaccination programmes for pregnant women in order to prevent whooping cough in infants aged less than 3 months

Measurement of CP-violating asymmetries in D0→π +π - and D0→K +K - decays at CDF

We report on a measurement of CP-violating asymmetries (A CP) in the Cabibbo-suppressed D0→π +Ï€ - and D0→K +K - decays reconstructed in a data sample corresponding to 5.9fb -1 of integrated luminosity collected by the upgraded Collider Detector at Fermilab. We use the strong decay D *+→D0Ï€ + to identify the flavor of the charmed meson at production and exploit CP-conserving strong ccÌ„ pair production in ppÌ„ collisions. High-statistics samples of Cabibbo-favored D0→K -Ï€ + decays with and without a D *± tag are used to correct for instrumental effects and significantly reduce systematic uncertainties. We measure A CP(D0→π +Ï€ -)=(+0.22±0.24(stat) ±0.11(syst))% and A CP(D0→K +K -)=(-0.24±0.22(stat)±0.09(syst))%, in agreement with CP conservation. These are the most precise determinations from a single experiment to date. Under the assumption of negligible direct CP violation in D0→π +Ï€ - and D0→K +K - decays, the results provide an upper limit to the CP-violating asymmetry in D0 mixing, |ACPind(D0)|<0.13% at the 90% confidence level. © 2012 American Physical Society.This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A.P. Sloan Foundation; the Bundesministerium fü̈r Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; and the Academy of Finland.Peer Reviewe

Septic shock in pregnancy due to pyogenic sacroiliitis: a case report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Lenguaje metafórico en los elementos de Euclides

Este artículo1 es una reflexión sobre el carácter metafórico de los conceptos que aparecen en el lenguaje matemático y sus implicaciones sociales. El concepto de número, es un ejemplo de construcción metafórica. Según los escritos históricos que hasta hoy han sobrevivido, a este concepto se han tratado de acercar matemáticos de todos los tiempos, entre ellos los matemáticos de la Grecia Clásica. Se pretende mostrar que el concepto de número que aparece en los Elementos de Euclides, ha sido estructurado sobre uno de los tres tipos de metáforas tratados en el libro Poética de Aristóteles