Supervisory observer for parameter and state estimation of nonlinear systems using the DIRECT algorithm

A supervisory observer is a multiple-model architecture, which estimates the parameters and the states of nonlinear systems. It consists of a bank of state observers, where each observer is designed for some nominal parameter values sampled in a known parameter set. A selection criterion is used to select a single observer at each time instant, which provides its state estimate and parameter value. The sampling of the parameter set plays a crucial role in this approach. Existing works require a sufficiently large number of parameter samples, but no explicit lower bound on this number is provided. The aim of this work is to overcome this limitation by sampling the parameter set automatically using an iterative global optimisation method, called DIviding RECTangles (DIRECT). Using this sampling policy, we start with 1 + 2np parameter samples where np is the dimension of the parameter set. Then, the algorithm iteratively adds samples to improve its estimation accuracy. Convergence guarantees are provided under the same assumptions as in previous works, which include a persistency of excitation condition. The efficacy of the supervisory observer with the DIRECT sampling policy is illustrated on a model of neural populations

Working mothers and workplace discrimination: the role of prescriptive stereotypes, neosexism and status threat.

Across six studies and three distinct research phases, this program of research examines factors that contribute to the workplace discrimination that women, in particular mothers, experience. The first phase of research, comprising Studies 1-3, examines the prescriptive stereotypes of employed mothers and fathers, and the work and care expectations of mothers-to-be. The first study (N = 40) elicited, from students and a sample of working adults, the stereotypes associated with mothers under two different employment scenarios (full-time or part-time). The results of this study indicate that stereotypes associated with mothers employed on a full-time basis are overwhelmingly negative. Study 1b (N = 79) examined how presence of children are perceived to impact on the daily routine of a professional female employee in comparison to an identical male. This phase concludes with a partial replication of Marks and Houston (2002), which sought to determine the career and caring expectations of young women (Study 2; N = 112). This study found that the combination of caring for children and full-time employment is seen as less desirable than the care of children in combination with part-time employment. The key findings of phase one , that the most negative evaluations and the least desired pattern of work and care is reserved for mothers employed on a full-time basis, led to the second phase of studies. This second phase, comprising Studies 3 and 4, examines how mothers (and women) are evaluated in a workplace context. Specifically, phase two assesses which combination of employment (full-time or part-time, with or without teleworking) and parental scenarios (mothers versus childless women) invoke the greatest workplace penalties. Employing a between-subjects design, Study 3 (N = 134) found that when employed full-time, mothers who do not make use of a work-life balance initiative (e.g., teleworking) are the least likely to be appointed, and if appointed, receive a uniquely low starting salary in comparison to mothers who telework and childless women. These findings are replicated and extended in Study 4 (N = 166), which demonstrates that this discrimination is heightened by those who endorse (to a greater degree) traditional gender ideologies, as assessed by the Neosexism Scale (Tougas, Brown, Beaton, & Joly, 1995). Phase two indicates, overall, that in the workplace mothers who deviate most from prescriptive stereotypes of motherhood face the harshest penalties, particularly when assessed by those with more traditional gender ideologies. That discriminatory evaluations of mothers are disproportionally made by respondents with traditional gender ideologies, led to phase three. This final phase of research seeks to investigate one explanation (i.e., perceived status threat) as to why discrimination against working mothers is heightened amongst those higher in neosexism. Contrary to predictions, the final study of this dissertation (Study 5, N = 72) found that perceptions of social instability with regard to gender relations does not impact on the workplace evaluations of mothers employed full-time. Strengths and limitations of the current program of research are discussed and directions for future research outlined

Beyond the hospital door: a retrospective, cohort study of associations between birthing in the public or private sector and women's postpartum care

Background In Australia, maternity care is available through universal coverage and a parallel, competitive private health insurance system. Differences between sectors in antenatal and intrapartum care and associated outcomes are well documented but few studies have investigated differences in postpartum care following hospital discharge and their impact on maternal satisfaction and confidence. Methods Women who birthed in Queensland, Australia from February to May 2010 were mailed a self-report survey 4 months postpartum. Regression analysis was used to determine associations between sector of birth and postpartum care, and whether postpartum care experiences explained sector differences in postpartum well-being (satisfaction, parenting confidence and feeling depressed). Results Women who birthed in the public sector had higher odds of health professional contact in the first 10 days post-discharge and satisfaction with the amount of postpartum care. After adjusting for demographic and postpartum contact variables, sector of birth no longer had an impact on satisfaction (AOR 0.95, 99% CI 0.78-1.31), but any form of health professional contact did. Women who had a care provider’s 24 hour contact details had higher odds of being satisfied (AOR 3.64, 95% CI 3.00-4.42) and confident (AOR 1.34, 95% CI 1.08- 1.65). Conclusion Women who birthed in the public sector appeared more satisfied because they had higher odds of receiving contact from a health professional within 10 days post-discharge. All women should have an opportunity to speak to and/or see a doctor, midwife or nurse in the first 10 days at home, and the details of a person they can contact 24 hours a day

Parameter and state estimation for a class of neural mass models

We present an adaptive observer which asymptotically reconstructs the parameters and states of a model of interconnected cortical columns. Our study is motivated by the fact that the considered model is able to realistically reproduce patterns seen on (intracranial) electroencephalograms (EEG) by varying its parameters. Therefore, by estimating its parameters and states, we could gain a better understanding of the mechanisms underlying neurological phenomena such as seizures, which might lead to the prediction of the onsets of epileptic seizures. Simulations are performed to illustrate our results

A robust circle criterion observer with application to neural mass models

A robust circle criterion observer is designed and applied to neural mass models. At present, no existing circle criterion observers apply to the considered models, i.e. the required linear matrix inequality is infeasible. Therefore, we generalise available results to derive a suitable estimation algorithm. Additionally, the design also takes into account input uncertainty and measurement noise. We show how to apply the observer to estimate the mean membrane potential of neuronal populations of a popular single cortical column model from the literature

A circle criterion observer for estimating the unmeasured membrane potential of neuronal populations

A circle criterion observer is designed for estimating the unmeasured membrane potential of neuronal populations using the electroencephalogram (EEG) from a class of parameterised models that replicates patterns seen on the EEG. Compared to existing similar designs, we provide a less conservative linear matrix inequality (LMI) condition that is shown to be fulfilled for the neural models we consider. The designed observer is robust towards disturbances in the input and measurement, as well as model uncertainty. We show that the observer can be designed for a model that reproduces alpha rhythms in the EEG as an illustrative example

Expression of flavour preferences conditioned by caffeine is dependent on caffeine deprivation state

Rationale: The acquisition of a caffeine conditioned flavour preference depends on the caffeine deprivation status of subjects during conditioning. It is not known if the expression of an established flavour preference is also state-dependent. Objectives: To determine if the expression of a flavour preference conditioned by caffeine is dependent on the level of deprivation at the time of testing. Methods: In a double-blind placebo controlled study, 44 subjects were given 4 days exposure to a novel flavoured drink following overnight abstinence from caffeine. Half the subjects received caffeine (100 mg) in the drink, while the remainder had placebo (maltodextrin, 100 mg). Subjects rated the pleasantness of the drink each time. On a fifth (test) day, the subjects were given additional caffeine (100 mg) or placebo 2 h before consuming and rating the pleasantness of the drink. Results: Pleasantness ratings for the novel drink increased over the 4 conditioning days in subjects receiving caffeine, but decreased in those given placebo. On day 5, subjects who were trained and tested in the same caffeine deprivation state expressed pleasantness ratings similar to those for the final training day. In contrast, subjects who were trained and tested in different states expressed pleasantness ratings that were significantly different from those of the final training day. Conclusions: These results suggest that the expression of caffeine conditioned flavour preferences are acutely sensitive to current motivational state, and a number of possible explanations are discussed