Quantitative ultraviolet measurements on wetted thin-layer chromatography plates using a charge-coupled device camera

This paper presents the first study of the UV imaging of spots on thin-layer chromatographic plates whilst still wet with solvent. Imaging of spots of benzophenone during and after development was carried out using a charge-coupled device camera. Limits of detection were found to be 5 ng on a wetted plate and 3 ng for a dry plate and the relationship between peak area and sample loading was found to be linear in the low nanograrn range over an order of magnitude for both wet and dry modes with r(2) values > 0.99. It was found that UV measurements on wet glass-backed plates suffer from low sensitivity; however, the use of aluminium-backed plates gave increased sensitivity. The apparent absorption coefficient (epsilon(app)) of 10AU m(2) g(-1) at 254 nm is consistent with reflection of the light from the aluminium surface with a double pass through the sorbent layer, and suggests that use of aluminium-backed plates should enable monitoring of separations by UV absorbance during TLC development. (c) 2008 Elsevier B.V. All rights reserved

Measuring the Impact of Genetic and Environmental Risk and Protective Factors on Speech, Language, and Communication Development-Evidence from Australia

Speech and language acquisition is one of the key development indicators of optimal literacy development in infancy and early childhood. Over the last decade there has been increasing interest in the development of theoretical frameworks which underpin the underlying complexity of a child's language developmental landscapes. This longitudinal study aims to measure the impact of genetic and environmental risk and protective factors on speech, language, and communication development (SLCN) among 5000 infants in Australia. Using robust panel fixed-effects models, the results demonstrate that there are clear and consistent effects of protective factors and SLCN associated with the infant's family [coefficient (SD) = 0.153, 95% standard error (SE) = 8.76], the in utero environment [coefficient (SD) = 0.055, standard error (SE) = 3.29] and early infant health [coefficient (SD) = 0.074, standard error (SE) = 5.28]. The impact of family and in utero health is dominant at aged 2 to 3 years (relative to 0 to 1 years) across the domains of language and communication and more dominant from birth to 1 years for speech acquisition. In contrast, the evidence for the impact of genetics on SLCN acquisition in infancy, is less clear. The evidence from this study can be used to inform intervention policies

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 impact of childhood language difficulties on healthcare costs from 4 to 13 years: Australian longitudinal study

© 2016 The Speech Pathology Association of Australia Limited Published by Taylor & Francis. Purpose: This study investigated the relationship between children’s language difficulties and health care costs using the 2004–2012 Longitudinal Study of Australian Children (LSAC). Method: Language difficulties were defined as scores ≤1.25SD below the standardised mean on measures of directly assessed receptive vocabulary (4–9 years) and teacher-reported language and literacy (10–13 years). Participant data were individually linked to administrative data, which were sourced from Australia’s universal subsidised healthcare scheme (Medicare). Result: It was found that healthcare costs over each 2-year age band were higher for children with language difficulties than without in the 4–5-year-age bracket (mean difference = AU$357, 95$59, $659), in the 6–7-year-age bracket (mean difference = AU$602, 95%CI $136,$1068) and in the 10–11-year-age bracket (mean difference = AU$504, 95$153, $854). Out-of-pocket costs, that is the portion of healthcare costs paid for by the family, were also higher for children with than without language difficulties in the 4–5-year-age bracket (mean difference = AU$123, 95%CI $46,$199), in the 6–7-year-age bracket (mean difference = AU$176, 95$74,278) and in the 10–11-year-age bracket (mean difference = AU$79, 95$6, $152). Medical services accounted for 97% of total healthcare cost differences. Conclusion: Overall the findings from this study suggest that language difficulties are associated with increased healthcare costs at key developmental milestones, notably early childhood and as a child approaches the teenage years

Choosing a Doctor: Does Presentation Format Affect the Way Consumers Use Health Care Performance Information?

© 2017, Springer International Publishing Switzerland. Background: Choosing a new health service provider can be difficult and is dependent on the type and clarity of the information available. This study examines if the presentation of service quality information affects the decisions of consumers choosing a general medical practice. Objectives: The aim was to examine the impact of presentation format on attribute level interpretation and relative importance. Methods: A discrete choice experiment eliciting preferences for a general medical practice was conducted using four different presentation formats for service quality attributes: (1) frequency and percentage with an icon array, (2) star ratings, (3) star ratings with a text benchmark, and (4) percentage alone. A total of 1208 respondents from an online panel were randomised to see two formats, answering nine choices for each, where one was a dominated choice. Logistic regression was used to assess the impact of presentation format on the probability of choosing a dominated alternative. A generalised multinomial logit model was used to estimate the relative importance of the attribute levels. Results: The probability of incorrectly choosing a dominated alternative was significantly higher when the quality information was presented as a percentage relative to a frequency with icon array, star rating or bench-marked star rating. Preferences for a practice did not differ significantly by presentation format, nor did the probability of finding the information difficult to understand. Conclusions: Quantitative health service quality information will be more useful to consumers if presented by combining the numerical information with a graphic, or using a star rating if appropriate for the context

The International Impact of COVID-19 and "Emergency Remote Teaching" on Computer Science Education Practitioners

The COVID-19 pandemic has imposed "emergency remote teaching" across education globally, leading to the closure of institutions across all settings, from schools through to universities. This paper looks specifically at the impact of these disruptive changes to those teaching the discipline of computer science. Drawing on the quantitative and qualitative findings from a large-scale international survey (N=2,483) conducted in the immediate aftermath of closures, implementation of lockdown measures, and the shift to online delivery in March 2020, we report how those teaching computer science across all educational levels (n=327) show significantly more positive attitudes towards the move to online learning, teaching and assessment (LT&A) than those working in other disciplines. When comparing educational setting, computer science practitioners in schools felt more prepared and confident than those in higher education; however, they expressed greater concern around equity and whether students would be able to access the teaching made available online. Furthermore, while practitioners across all sectors consistently noted the potential opportunities of these changes, they also raised a number of wider concerns on the impact of this shift to online, especially on workload and job precarity. More specifically for computer science practitioners, there were concerns raised regarding the ability to effectively deliver technical topics online, as well as the impact on various types of formal examinations and assessment. We also offer informed commentary from this rapid response international survey on emerging LT&A strategies that will likely continue to be constrained by coronavirus into 2021 and possibly beyond

Animal movement modelling: Independent or dependent models?

Hidden Markov models have become a popular time series method for the analysis of GPS tracked animals. Their advantage for identifying latent behavioural states compared with Independent Mixture models is that they take into account the time series dependency of successive displacement distances by the tracked animals. However, little is known about how the analysis results may differ depending on which of these approaches is used. We compared the results and interpretations obtained from fitting Hidden Markov and Independent Mixture models to simulated movement data as well as to field data recording the hourly movements of sable antelope and buffalo within the Kruger National Park, South Africa. Hidden Markov models consistently yielded narrower confidence intervals around parameters and smaller standard errors than simpler time independent mixture models, but for some data the improvement was marginal and the Independent Mixture model provided an adequate alternative for identifying the latent behavioural states of the animal. In general, it is expected Hidden Markov models will provide the better balance between model complexity and extensibility for animal movement modelling from a statistical perspective. However, in some cases, Independent Mixture models could provide an adequate alternative method and might be more faithful biologically