On the nonlinearly structured stability radius problem

This paper considers the problem of finding a perturbation matrix with the least spectral norm such that a matrix-valued function becomes singular, where the dependence of the function on the perturbation is allowed to be nonlinear. It is proved that such a problem can be approximated by a smooth unconstrained minimization problem with compact sublevel sets. A computational procedure proposed based on this result is demonstrated to be effective in both linear and nonlinear cases.published_or_final_versio

On quadratic stability of systems with structured uncertainty

This note considers the problem of stability robustness with respect to a class of nonlinear time-varying perturbations which are bounded in a component-wise rather than aggregated manner. A family of robustness bounds is parameterized in terms of a nonsingular symmetric matrix. It is shown that the problem of computing the largest robustness bound over the set of nonsingular symmetric matrices can be approximated by a smooth minimization problem over a compact set. A convergent algorithm for computing an optimal robustness bound is proposed in the form of a gradient flow.published_or_final_versio

An approximate approach to H 2 optimal model reduction

This paper deals with the problem of computing an H 2 optimal reduced-order model for a given stable multivariable linear system. By way of orthogonal projection, the problem is formulated as that of minimizing the H 2 model-reduction cost over the Stiefel manifold so that the stability constraint on reduced-order models is automatically satisfied and thus totally avoided in the new problem formulation. The closed form expression for the gradient of the cost over the manifold is derived, from which a gradient flow results as an ordinary differential equation (ODE). A number of nice properties about such a flow are established. Furthermore, two explicit iterative convergent algorithms are developed from the flow; one has a constant step-size and the other has a varying step-size and is much more efficient. Both of them inherit the properties that the iterates remain on the manifold starting from any orthogonal initial point and that the model reduction cost is decreasing to minima along the iterates. A procedure for closing the gap between the original and modified problem is proposed. In the symmetric case, the two problems are shown to be equivalent. Numerical examples are presented to illustrate the effectiveness of the proposed algorithms as well as convergence.published_or_final_versio

The family may be the rescue when your heart starts to sink

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Effects of shear connectors on plate-reinforced composite coupling beams of short and medium-length spans

Experimental studies on the newly proposed design of plate-reinforced composite (PRC) coupling beams have been carried out. Previous results have demonstrated the useful application of this design in coupling beams of medium span-to-depth ratios (l/h) under both inelastic seismic and elastic wind loading. This paper presents further experimental studies on five PRC coupling beams, which investigated the importance of shear connectors on plate/reinforced concrete composite action. Three medium-length (l/h=2.5) and two short (l/h=1.17) PRC coupling beams, each containing a vertically embedded steel plate, were tested under reversed cyclic loading. While one short beam was welded with expanded metal meshes on the plate surfaces, others were welded with shear studs on the plates in the wall regions and/or the beam spans. Results showed that the expanded metal meshes did not work effectively, and while the shear studs in the beam span only slightly increased the beam capacity, those in the wall regions contributed considerably in improving inelastic beam performance. © 2005 Elsevier Ltd. All rights reserved.postprin

Validation of the International Prostate Symptoms Score in Chinese males and females with lower urinary tract symptoms

Objectives To evaluate the translation of the IPSS (Hong Kong Chinese version 1) and to assess the applicability, validity, reliability and sensitivity of the instrument in both males and females with LUTS in Chinese population. Methods The translation of the IPSS (Hong Kong Chinese version 1) was reviewed through back translation. Modifications were made, resulting in the development of The IPSS (Hong Kong Chinese version 2). The content validity was assessed by contend validity index. 233 subjects with LUTS were recruited in Hong Kong primary care settings for pilot psychometric testing. The construct validity was assessed by corrected item-total correlation and Pearson’s correlation test against ICIQ-UI SF, IIQ-7 and SF-12 v2. The reliability was assessed by the internal consistency (Cronbach’s Alpha coefficient) and test –retest reliability (Intraclass correlation coefficient). The Sensitivity was determined by performing known group comparisons by independent T-test. Results The content validity index for all items could reach 1. Corrected item-total correlation scores were ≥0.4 for four symptom questions (feeling of incomplete bladder emptying, intermittency, weak stream and straining). Overall, the total symptom score moderately correlated with ICIQ-UI SF. The quality of life score moderately correlated with the IIQ-7 but weakly correlated with SF-12 v2. Overall, the reliability of the IPSS (Hong Kong Chinese version 2) was acceptable (Cronbach’s Alpha coefficient = 0.71, ICC of the symptom questions =0.8, ICC of the quality of life question =0.7). The symptoms questions and quality of life questions of the IPSS (Hong Kong Chinese versions 2) were sensitive in detecting differences between groups. Conclusions The IPSS (Hong Kong Chinese version 2) is a valid, reliable and sensitive measure to assess Chinese females and males with lower urinary tract symptoms. The IPSS quality of life question is more sensitive than the generic quality of life measure to differentiate subgroups.published_or_final_versio

Quality of care of nurse-led and allied health personnel-led primary care clinics

Objectives To review the literature regarding quality of care of nurse-led and allied health personnel-led primary care clinics with specific attention to the quality indicators for fall prevention, continence care, pulmonary rehabilitation, mental health, pharmaceutical care, and wound care services. Data sources Literature search from 1990 to 2010 including Ovid Medline, Cochrane Database, RAND (Research and Development) Corporation Health Database, the ACOVE (Assessing the Care of Vulnerable Elders) project and clinical guidelines from the United Kingdom, Australia, Canada, and the United States. Study selection This review was limited to studies involving adult, primary care patients. Where available, evidence from systematic reviews and meta-analyses were used to synthesize findings. Data extraction Combinations of the following terms (and related terms) were used to identify studies: primary care, clinic, allied-health, nurse-led, fall prevention, continence care, incontinence, chronic obstructive pulmonary disorder, pulmonary disease, respiratory rehabilitation, mental health, mental wellbeing, depression, anxiety, wound care, leg ulcer, venous ulcer, dressings clinic, wound clinic, medication review, pharmacist-led, pharmaceutical care. Data synthesis A total of 21 international guidelines and 33 studies were selected for data synthesis. Despite a lack of consistent outcomes data, it is apparent that certain aspects of organizational structure and clinical care processes are important though not necessarily sufficient indicators of quality of care, because they themselves can influence care outcomes. Seven key factors were identified which seem important determinants of the quality of care provided by nurse- and allied health personnel-led clinics. Conclusion Delivery of primary health care by nurse and allied health personnel-led teams is a well-established model, internationally. Evidence from the literature provides benchmarks for standards of good practice. Knowledge of factors influencing quality of care can assist the planning, implementation, evaluation, and further expansion of such programmes, locally.published_or_final_versio

12-Month naturalistic outcomes of depressive disorders in Hong Kong's primary care

Open Access Journalpublished_or_final_versio

Help-seeking intentions and subsequent 12-month mental health service use in Chinese primary care patients with depressive symptoms

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Elaboration analysis of the relationship between delivery model and educational attainment

As the programme to renew secondary school buildings gathers pace, questions are being asked if the investment is producing results in improved educational attainment. This research sought to verify finding from earlier research that educational attainment improved faster in PFI rebuilt schools compared to conventionally- procured rebuilt schools. Quantitative analysis, incorporating the latest data, was performed and the finding was confirmed, though statistical significance was not universally established due to large variance within the dataset and small sample size. The finding was deemed note-worthy still because the sample included all the rebuilt schools with complete longitudinal data. Further quantitative analysis was performed to elaborate on this finding. Unauthorised absence was used as a proxy to students' motivation. Analysis results provided some, evidence of statistical significance for the hypothesis that PFI rebuilt schools improve students' motivation more than conventionally-procured rebuilt schools. In addition, a significant correlation was found to exist between improved students' motivation and improved educational attainment. Therefore, students' motivation elaborated the original finding thus: PFI rebuilt schools improved students' motivation more which showed up in faster improvement in educational attainment. As an extension to the elaboration analysis, a conceptual framework was developed to build a comprehensive understanding of the mechanism through which the original relationship works. Path analysis, together with its path diagram and associated structural equations, was proposed. This paved the way to an in-depth quantitative analysis to unpick the complex nature of the relationship between procurement choice and educational attainment in the next stage of research