On the resultant property of the Fisher information matrix of a vector ARMA process

A matrix is called a multiple resultant matrix associated to two matrix polynomials when it becomes singular if and only if the two matrix polynomials have at least one common eigenvalue. In this paper a new multiple resultant matrix is introduced. It concerns the Fisher information matrix (FIM) of a stationary vector autoregressive and moving average time series process (VARMA). The two matrix polynomials are the autoregressive and the moving average matrix polynomials of the VARMA process. In order to show that the FIM is a multiple resultant matrix two new representations of the FIM are derived. To construct such representations appropriate matrix differential rules are applied. The newly obtained representations are expressed in terms of the multiple Sylvester matrix and the tensor Sylvester matrix. The representation of the FIM expressed by the tensor Sylvester matrix is used to prove that the FIM becomes singular if and only if the autoregressive and moving average matrix polynomials have at least one common eigenvalue. It then follows that the FIM and the tensor Sylvester matrix have equivalent singularity conditions. In a simple numerical example it is shown however that the FIM fails to detect common eigenvalues due to some kind of numerical instability. Whereas the tensor Sylvester matrix reveals it clearly, proving the usefulness of the results derived in this paper. © 2005 Elsevier Inc. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Corrections to "Construction of the exact Fisher information matrix of Gaussian time series models by means of matrix differential rules"

This note contains some corrections and amplifications that were deduced from the implementation and testing of the method

Sex steroid dynamics during embryogenesis and sexual differentiation in Eurasian perch, Perca fluviatilis

It is widely accepted that sex steroid hormones play an important and a specific role during the process of sex differentiation in fish. In order to describe the role of the three main sex steroid hormones (testosterone--T, 17beta-estradiol--E2 and 11keto-testosterone--11KT) during embryogenesis and sex differentiation in Eurasian perch, Perca fluviatilis, eggs, larvae and juveniles originating from two mixed-sex and two all-female progenies were regularly sampled from fertilization to hatching (D0) and from hatching to day 70 post-hatching (D70). Just after spawning, a significant amount of sex steroids [T (1634.2pgg(-1)), E2 (554.4pgg(-1)) and 11KT (1513.2pgg(-1))] was measured in non-fertilised eggs suggesting a maternal transmission of these steroids. From D2 to D70 post-hatching, E2 levels were significantly higher in mixed-sex progenies (median: 725.7pgg(-1)) than in all-female progenies (156.2pgg(-1)) and significantly increased after the onset of the histological differentiation of the gonad in both progenies (D35). Levels of 11KT were significantly higher in mixed-sex (median: 431.5pgg(-1)) than in all-female progenies (below the limit of assay detection) and significantly increased at D35 in all-female progenies (median value: 343.2pgg(-1)). Mean 11KT to E2 ratio was six-fold higher in mixed-sex progenies (1.35) than in all-female progenies (0.24). The data suggest that the 11-oxygenated androgen (11KT) plays a major role in the male differentiation process, and that sex differentiation in Eurasian perch is probably determined by the 11KT to E2 ratio

The Association Between Smoke-Free School Policies and Adolescents’ Perceived Antismoking Norms: Moderation by School Connectedness

© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco.BACKGROUND: Many European schools implement smoke-free school policies (SFSPs). SFSPs may decrease adolescent smoking by causing adolescents to perceive stronger anti-smoking norms, yet there exists no quantitative evidence that indicates for which norms and for whom such effects may occur. This study therefore assessed to what extent adolescents' perceived anti-smoking norms among best friends, teachers, and society at large were associated with SFSPs, and whether these associations were moderated by adolescents' level of school connectedness. METHODS: Survey data were collected in 2016/2017 on 10,653 14-16-year-old adolescents and 315 staff members in 55 schools from seven European cities. Associations of adolescent-perceived SFSPs and staff-reported SFSPs with best friend, teacher and societal anti-smoking norms were estimated in multilevel logistic regression models, adjusted for demographics and school-level smoking prevalence. We tested for interaction between school connectedness and SFSPs. RESULTS: Adolescent-perceived SFSPs were positively associated with anti-smoking norms by teachers (OR:1.46, 95%CI:1.15-1.85), were negatively associated with anti-smoking norms by best friends (OR:0.81, 95%CI:0.67-0.99), but were not significantly associated with anti-smoking norms by society at large (OR:0.87, 95%CI:0.74-1.02). All interaction tests between adolescent-perceived SFSPs and school connectedness were non-significant. Staff-reported SFSPs were not associated with any norm and showed no significant interaction with school connectedness. CONCLUSIONS: We found that SFSPs are associated with adolescents' perception of more anti-smoking norms by teachers, but less anti-smoking norms by best friends, irrespective of adolescents' level of school connectedness. IMPLICATIONS: Smoke-free school policies, just as many other tobacco control policies, are assumed to foster adolescents' perception of anti-smoking norms. Still, current evidence does not demonstrate which anti-smoking norms may be influenced by SFSPs and whether this influence is equal for adolescents with different levels of school connectedness. This study suggests that SFSPs foster adolescents' perception of anti-smoking norms by teachers, but may concurrently lead to the perception of less anti-smoking norms by best friends, irrespective of adolescents' school connectedness. SFSPs may therefore need to be complemented with interventions that target anti-smoking norms in adolescent peer groups.authorsversionpublishe

Where do teens smoke? Smoking locations of adolescents in Europe in relation to smoking bans in bars, schools and homes

This study aimed to assess where European adolescents smoke. Data of 2,140 13-19-year-olds from 55 secondary schools in seven European cities was analysed using multilevel logistic regression analyses. Adolescents most often reported regularly smoking in ‘other public locations (e.g., streets and parks)’ (69%) and friends’ homes (50%). Adolescents were less likely to smoke in bars, at school or at home when exposed to strong smoking bans at these locations. Bans on smoking in bars or at home were associated with regular smoking in other public locations, suggesting that smoking may have displaced towards these locations

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Voer pikken, geen veren

Abstract The paper presents an algorithm for computing the asymptotic Fisher information matrix of a possibly seasonal single input single output (SISO) time series model. That matrix is a block matrix whose elements are basically integrals over the oriented unit circle of rational functions. The procedure makes use of the autocovariance function of one or the cross-covariance function of two autoregressive processes base