Symptomatology and health attitudes of chronic hepatitis B patients in the USA

This study was conducted to understand the symptomatology, attitudes, and behaviours of chronic hepatitis B (CHB) patients in the USA. CHB patients enrolled in this study were recruited through multiple methods, including newspaper advertisements. Interviews were conducted in multiple languages, and all participants had a history of CHB infection for at least 6 months. Patients with documented human immunodeficiency virus or hepatitis C virus coinfection were excluded from data analyses, resulting in a total study population of 258 respondents who completed interviews between April and June 2004. The majority of monoinfected patients were male (57%) and non-Asian (92%, including 52% Caucasian, 32% African American and others). Length of diagnosis was 5.8 years for all participants (9.1-year Asian and 5.1-year non-Asian). Ninety-five per cent of CHB patients reported symptoms of differing severity in the 12 months prior to the survey. The most common symptoms included fatigue/loss of energy (90%) and loss of appetite (79%). Non-Asian patients described greater symptomatology, and were more likely than Asians to consider CHB an overriding concern in their daily activities. Patients were treated either currently or previously with interferon (IFN) described greater symptomatology than those treated without IFN. Survey results indicate that CHB patients may have greater symptomatology than recognized. Disease perceptions and treatment attitudes differ between Asian and non-Asian ethnic groups, with the former appearing to be more accepting and less concerned about the disease. Additional research about CHB symptomatology and health attitudes by ethnicity is needed to ensure that individuals with CHB are educated on the potential health risks and the availability of current treatment options

Unbiased estimation of the Hessian for iterative feedback tuning (IFT)

Iterative feedback tuning (IFT) is a data-based method for the optimal tuning of a low order controller. The tuning of the controller parameters is performed iteratively, using a generalized Robbins-Monro type gradient descent scheme. An update step of the controller parameters is performed at each iteration on the basis of data obtained partly during normal operating conditions and partly from some special experiments. These data come from the closed loop system with the current controller. This paper presents a simple improvement to the IFT scheme: it is shown that one can compute an unbiased estimate of the Hessian on the basis of additional experiments on the closed loop system.Anglai

Stability analysis of an infinite-dimensional linearized plug flow reactor model

A stability analysis is performed for a linearized plug flow reactor model. The dynamics of the linearized process are described by linear partial differential equations (PDE's) with spatial-dependent coefficients. The analysis is performed on an equivalent triangularized model, that is described by a triangular system of PDE's. Then the stability of the linearized model is established, by using the invariance of stability under system equivalence.Anglai

Boundary control design for cascades of hyperbolic 2 * 2 PDE systems via graph theory

The article is concerned with the design of boundary control laws for stabilizing systems of 2 * 2 first order quasi-linear hyperbolic PDEs. A new graph representation of such systems represents the interactions between the characteristic curves and the boundary control laws, the invariant graph, is introduced. The structure of the invariant graph is used to design stabilizing control laws and an analytical stability condition is given.Anglai