Solutions to Wiener Filtering and Stationary LQG Problem via H₂ Control Theory - Part II : Discrete - Time System

This paper derives the solutions to the Wiener filtering and stationary LQG problem for a discrete-time system by applying the state-space techniques developed for H₂H∞ optimal controls. As mathematical preliminaries, we collect useful operations for the transfer function matrices. We also provide a new proof for the inner-outer factorization algorithm that appears in the discrete-time H₂ optimization

Parametrization of All Stable Unbiased ℋ∞ Estimators Based on Model Matching

This paper considers the H∞ estimation problem by using a model matching technique. For a given possibly unstable plant, the H∞ estimation problem is reduced to a standard model matching problem by introducing a class of all stable and unbiased estimators. Based on Nehari's theorem, a necessary and suffcient condition for the existence of a solution of the H∞ estimation problem is derived in terms of an H∞-type algebraic Riccati equation. The LFT representation of the class of all solutions is also developed

Parameter Identification of Image Models by the Recursive Maximum Likelihood Method

This paper considers the problem of identifying the blur parameters of the observed image. It is assumed that the original image is a sample from the homogeneous random field described by a two-dimensional (2-D) semicausal model, and that the point spread function (PSF) characterizing the image blur is symmetric. It is also assumed that the observation noise is negligibly small. By applying the discrete sine transform, we derive a set of nearly uncorrelated ARMA models, which are of non-minimum phase, for the blurred image. Although all-pass components of the MA part of the models can not be estimated, we show that the parameters of the non-minimum phase MA part can be restored by exploiting the fact that the PSF is symmetric. We develop a new algorithm for identifying the blur parameters of the image model from the MA parameters estimated by the recursive maximum likelihood (RML) method. Simulation studies are also included to show the feasibility of the algorithm

Solutions to Wiener Filtering and Stationary LQG Problems via H₂ Control Theory-Part I : Continuous-Time System

This paper derives solutions to the multivariable Wiener filtering and the stationary LQG problems using the H₂ optimal control theory and the state-space technique. Inner-outer factorization and spectral factorization results arising in H₂/H∞ optimal controls are also derived by the state-space technique

A Subspace Identification of δ-Operator State-Space Model

This paper derives a subspace identification algorithm for a δ-operator state-space model by using the methods due to Moonen et al. [11], [12], [21]. Since the δ-operator model converges to a continuous-time model as the sampling interval goes to zero, the algorithm obtained is applicable to the identification of continuous-time medels. A method of computing the state vector from the block Hankel matrix is developed. Simulation studies show the present algorithm provides good results for the case of a low N/S ratio. Improvement of the algorithm for the case of a higher N/S ratio remains to be done

Application of Maximum Likelihood Method to Boiler System Identification

A maximum likelihood (ML) method is applied to a boiler system identification. The mathematical model used in this paper is a discrete-time, singleinput and single-output (SISO), constant, linear system excited by an “innovation” process. Since the ML identification is reduced to a nonlinear optimization problem with equality constraints, the Davidon's conjugate gradient method is employed for numerical solutions. By using the given input/output data, the dynamics of the governor/steam pressure and the governor/steam temperature relations are identified as an SISO system, respectively. AIC and a test based on the innovation process are also applied for selecting an appropriate order of the assumed model

Expression of human mutant cyclin dependent kinase 4, Cyclin D and telomerase extends the life span but does not immortalize fibroblasts derived from loggerhead sea turtle (Caretta caretta)

Conservation of the genetic resources of endangered animals is crucial for future generations. The loggerhead sea turtle (Caretta caretta) is a critically endangered species, because of human hunting, hybridisation with other sea turtle species, and infectious diseases. In the present study, we established primary fibroblast cell lines from the loggerhead sea turtle, and showed its species specific chromosome number is 2n = 56, which is identical to that of the hawksbill and olive ridley sea turtles. We first showed that intensive hybridization among multiple sea turtle species caused due to the identical chromosome number, which allows existence of stable hybridization among the multiple sea turtle species. Expressions of human-derived mutant Cyclin-dependent kinase 4 (CDK4) and Cyclin D dramatically extended the cell culture period, when it was compared with the cell culture period of wild type cells. The recombinant fibroblast cell lines maintained the normal chromosome condition and morphology, indicating that, at the G1/S phase, the machinery to control the cellular proliferation is evolutionally conserved among various vertebrates. To our knowledge, this study is the first to demonstrate the functional conservation to overcome the negative feedback system to limit the turn over of the cell cycle between mammalian and reptiles. Our cell culture method will enable the sharing of cells from critically endangered animals as research materials

Drug retention of secondary biologics or JAK inhibitors after tocilizumab or abatacept failure as first biologics in patients with rheumatoid arthritis -the ANSWER cohort study-

Objectives: The aim of this multicenter, retrospective study was to clarify the retention of secondary biological disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase inhibitors (JAKi) in patients with rheumatoid arthritis (RA) who were primarily treated by tocilizumab (TCZ) or abatacept (ABT) as first bDMARDs. Method: Patients who were treated by either TCZ (n = 145) or ABT (n = 76) and then switched to either tumor necrosis factor inhibitors (TNFi), TCZ, ABT, or JAKi (including only cases switched from TCZ) from 2001 to 2019 (female 81.0%, age 59.5 years, disease duration 8.8 years; rheumatoid factor positivity 75.4%; Disease Activity Score in 28 joints using C-reactive protein 3.7; concomitant prednisolone (PSL) dose 6.0 mg/day (51.8%) and methotrexate (MTX) dose 8.0 mg/week (56.1%); 81.9% discontinued first bDMARDs due to lack of effectiveness) were included. Drug retention and discontinuation reasons were estimated at 24 months using the Kaplan-Meier method and adjusted for potential confounders by Cox proportional hazards modeling. Results: Drug retentions for each of the reasons for discontinuation were as follows: lack of effectiveness in TCZ-switched group (TNFi (59.5%), ABT (82.2%), and JAKi (84.3%); TNFi vs. ABT; P = 0.009) and ABT-switched group (TNFi (79.6%) and TCZ (92.6%); P = 0.053). Overall retention excluding non-toxic reasons and remission for discontinuation were TNFi (49.9%), ABT (72.7%), and JAKi (72.6%) (TNFi vs. ABT; P = 0.017) in the TCZ-switched group and TNFi (69.6%) and TCZ (72.4%) (P = 0.44) in the ABT-switched group. Conclusions: Switching to ABT in TCZ-treated patients led to higher retention as compared with TNFi. Switching to TCZ in ABT-treated patients tended to lead to higher retention due to effectiveness, although total retention was similar as compared with TNFi.Key Point• This is the first retrospective, multi-center study aimed to clarify the retention rates of secondary bDMARDs or JAKi in patients with RA who were primarily being treated by TCZ or ABT as the first bDMARDs.This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s10067-020-05015-5Ebina K., Hirano T., Maeda Y., et al. Drug retention of secondary biologics or JAK inhibitors after tocilizumab or abatacept failure as first biologics in patients with rheumatoid arthritis -the ANSWER cohort study-. Clinical Rheumatology 39, 2563 (2020