On designing observers for time-delay systems with nonlinear disturbances

This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2002 Taylor & Francis LtdIn this paper, the observer design problem is studied for a class of time-delay nonlinear systems. The system under consideration is subject to delayed state and non-linear disturbances. The time-delay is allowed to be time-varying, and the non-linearities are assumed to satisfy global Lipschitz conditions. The problem addressed is the design of state observers such that, for the admissible time-delay as well as non-linear disturbances, the dynamics of the observation error is globally exponentially stable. An effective algebraic matrix inequality approach is developed to solve the non-linear observer design problem. Specifically, some conditions for the existence of the desired observers are derived, and an explicit expression of desired observers is given in terms of some free parameters. A simulation example is included to illustrate the practical applicability of the proposed theory.The work of Z. Wang was supported in part by the University of Kaiserslautern of Germany and the Alexander von Humboldt Foundation of Germany

The inverse-Compton ghost HDF 130 and the giant radio galaxy 6C 0905+3955: matching an analytic model for double radio source evolution

We present new GMRT observations of HDF 130, an inverse-Compton (IC) ghost of a giant radio source that is no longer being powered by jets. We compare the properties of HDF 130 with the new and important constraint of the upper limit of the radio flux density at 240 MHz to an analytic model. We learn what values of physical parameters in the model for the dynamics and evolution of the radio luminosity and X-ray luminosity (due to IC scattering of the cosmic microwave background (CMB)) of a Fanaroff-Riley II (FR II) source are able to describe a source with features (lobe length, axial ratio, X-ray luminosity, photon index and upper limit of radio luminosity) similar to the observations. HDF 130 is found to agree with the interpretation that it is an IC ghost of a powerful double-lobed radio source, and we are observing it at least a few Myr after jet activity (which lasted 5--100 Myr) has ceased. The minimum Lorentz factor of injected particles into the lobes from the hotspot is preferred to be $\gamma\sim10^3$ for the model to describe the observed quantities well, assuming that the magnetic energy density, electron energy density, and lobe pressure at time of injection into the lobe are linked by constant factors according to a minimum energy argument, so that the minimum Lorentz factor is constrained by the lobe pressure. We also apply the model to match the features of 6C 0905+3955, a classical double FR II galaxy thought to have a low-energy cutoff of $\gamma\sim10^4$ in the hotspot due to a lack of hotspot inverse-Compton X-ray emission. The models suggest that the low-energy cutoff in the hotspots of 6C 0905+3955 is $\gamma\gtrsim 10^3$, just slightly above the particles required for X-ray emission.Comment: 9 pages, 3 figure

Primary Connections: Linking science with literacy Stage 6 research evaluation final report

This report presents findings from the External Independent Evaluation and Research for Primary Connections Stage 6 (2014–2018) conducted by a research team from the University of Technology Sydney (UTS)

Thermodynamic Signature of a Two-Dimensional Metal-Insulator Transition

We present a study of the compressibility, K, of a two-dimensional hole system which exhibits a metal-insulator phase transition at zero magnetic field. It has been observed that dK/dp changes sign at the critical density for the metal-insulator transition. Measurements also indicate that the insulating phase is incompressible for all values of B. Finally, we show how the phase transition evolves as the magnetic field is varied and construct a phase diagram in the density-magnetic field plane for this system.Comment: 4 pages, 4 figures, submitted to Physical Review Letters; version 1 is identical to version 2 but didn't compile properl

Compromised OX40 function in CD28-deficient mice is linked with failure to develop CXC chemokine receptor 5-positive CD4 cells and germinal centers

Mice rendered deficient in CD28 signaling by the soluble competitor, cytotoxic T lymphocyte-associated molecule 4-immunoglobulin G1 fusion protein (CTLA4-Ig), fail to upregulate OX40 expression in vivo or form germinal centers after immunization. This is associated with impaired interleukin 4 production and a lack of CXC chemokine receptor (CXCR)5 on CD4 T cells, a chemokine receptor linked with migration into B follicles. Germinal center formation is restored in CTLA4-Ig transgenic mice by coinjection of an agonistic monoclonal antibody to CD28, but this is substantially inhibited if OX40 interactions are interrupted by simultaneous injection of an OX40-Ig fusion protein. These data suggest that CD28-dependent OX40 ligation of CD4 T cells at the time of priming is linked with upregulation of CXCR5 expression, and migration of T cells into B cell areas to support germinal center formation

Fishing the georges river: Cultural diversity and urban environments

The Georges River runs through the heart of Sydney’s most culturally diverse population, including long-established Aboriginal and Anglo-Celtic communities as well as the many more recent immigrant communities that have developed since the 1980s. Most people in all these communities are in working-class employment (if they have jobs at all), are living in densely packed suburbs and, despite some gentrification on the margins, still have significant disadvantages in educational and social infrastructure. As well as being a large river with scenic parklands threading along its lower estuarine reaches, the Georges River is also the focus of intensifying ethnic conflicts which often spill over into the media. The names of the river’s suburbs – Cabramatta, Liverpool, Bankstown, Macquarie Fields and Lakemba – are well known around Australia for their tensions. Yet, recent surveys of Australian attitudes to cultural diversity have demonstrated a widespread endorsement of the desire to reach across cultural differences despite the effect of international events and the media in increasing the hostile polarisation between ethnic groups (Ang et al. 2002, 2006). This paper will ask whether considering the area’s complex relationships and tensions through the lens of ‘everyday’ activities might allow us to understand those conflicts more clearly

Evaluation of the Victorian Healthy Homes Program: protocol for a randomised controlled trial.

INTRODUCTION: The evaluation of the Victorian Healthy Homes Program (VHHP) will generate evidence about the efficacy and cost-effectiveness of home upgrades to improve thermal comfort, reduce energy use and produce health and economic benefits to vulnerable households in Victoria, Australia. METHODS AND ANALYSIS: The VHHP evaluation will use a staggered, parallel group clustered randomised controlled trial to test the home energy intervention in 1000 households. All households will receive the intervention either before (intervention group) or after (control group) winter (defined as 22 June to 21 September). The trial spans three winters with differing numbers of households in each cohort. The primary outcome is the mean difference in indoor average daily temperature between intervention and control households during the winter period. Secondary outcomes include household energy consumption and residential energy efficiency, self-reported respiratory symptoms, health-related quality of life, healthcare utilisation, absences from school/work and self-reported conditions within the home. Linear and logistic regression will be used to analyse the primary and secondary outcomes, controlling for clustering of households by area and the possible confounders of year and timing of intervention, to compare the treatment and control groups over the winter period. Economic evaluation will include a cost-effectiveness and cost-benefit analysis. ETHICS AND DISSEMINATION: Ethical approval was received from Victorian Department of Human Services Human Research Ethics Committee (reference number: 04/17), University of Technology Sydney Human Research Ethics Committee (reference number: ETH18-2273) and Australian Government Department of Veterans Affairs. Study results will be disseminated in a final report and peer-reviewed journals. TRIAL REGISTRATION NUMBER: ACTRN12618000160235

Lack of seroresponse to SARS-CoV-2 booster vaccines given early post-transplant in patients primed pre-transplantation

SARS-CoV-2 vaccines are recommended pre-transplantation, however, waning immunity and evolving variants mandate booster doses. Currently there no data to inform the optimal timing of booster doses post-transplant, in patients primed pre-transplant. We investigated serial serological samples in 204 transplant recipients who received 2 or 3 SARS-CoV-2 vaccines pre-transplant. Spike protein antibody concentrations, [anti-S], were measured on the day of transplantation and following booster doses post-transplant. In infection-naïve patients, post-booster [anti-S] did not change when V3 (1st booster) was given at 116(78-150) days post-transplant, falling from 122(32-574) to 111(34-682) BAU/ml, p=0.78. Similarly, in infection-experienced patients, [anti-S] on Day-0 and post-V3 were 1090(133-3667) and 2207(650-5618) BAU/ml respectively, p=0.26. In patients remaining infection-naïve, [anti-S] increased post-V4 (as 2nd booster) when given at 226(208-295) days post-transplant, rising from 97(34-1074) to 5134(229-5680) BAU/ml, p=0.0016. Whilst in patients who had 3 vaccines pre-transplant, who received V4 (as 1st booster) at 82(49-101) days post-transplant, [anti-S] did not change, falling from 981(396-2666) to 871(242-2092) BAU/ml, p=0.62. Overall, infection pre-transplant and [anti-S] at the time of transplantation predicted post-transplant infection risk. As [Anti-S] fail to respond to SARS-CoV-2 booster vaccines given early post-transplant, passive immunity may be beneficial to protect patients during this period

Potentially Inappropriate Prescribing in Australian Nursing Home Residents with Advanced Dementia: A Substudy of the IDEAL Study

© 2018, Mary Ann Liebert, Inc. Background: Prescribing medications for nursing home residents with advanced dementia should focus on optimizing function and comfort, reducing unnecessary harms and aligning care goals with a palliative approach. Objective: The aim of the study was to estimate the proportion of Australian nursing home residents with advanced dementia receiving potentially inappropriate medications, and identify those most commonly prescribed and factors associated with their use. Design: Data were collected through retrospective audit of medication charts. Setting/Subjects: Two hundred eighteen nursing home residents with advanced dementia from 20 nursing homes participated in a cluster-randomized controlled trial of case conferencing (the IDEAL Study) from June 2013 to December 2014. Measurements: Inappropriate drug use was defined as medications classified as "never appropriate" by the Palliative Excellence in Alzheimer Care Efforts (PEACE) program criteria. Generalized linear mixed models were used to identify variables predicting use of "never" appropriate medications. Results: Over a quarter (n = 65, 30%) of residents received at least one medication classed as "never" appropriate, the most common being lipid-lowering agents (n = 38, 17.4%), antiplatelet agents (n = 18, 8.3%), and acetylcholinesterase inhibitors (n = 16, 7.3%). Residents who had been at the nursing home for ≤10 months (odds ratio [OR] 5.60, 95% confidence interval [CI] 1.74-18.06) and 11-21 months (OR 5.41, 95% CI 1.67-17.75) had significantly greater odds of receiving a never appropriate medication compared with residents who had been at the nursing home for >5 years. Conclusions: Use of potentially inappropriate medications in Australian nursing home residents with advanced dementia is common. A greater understanding of the rationale that underpins prescribing of medications is required