Secret objectives: promoting inquiry and tackling preconceptions in teaching laboratories

In its most general form, a `secret objective' is any inconsistency between the experimental reality and the information provided to students prior to starting work on an experiment. Students are challenged to identify the secret objectives and then given freedom to explore and understand the experiment, thus encouraging and facilitating genuine inquiry elements in introductory laboratory courses. Damping of a simple pendulum is used as a concrete example to demonstrate how secret objectives can be included. We also discuss the implications of the secret objectives method and how this can provide a link between the concepts of problem based learning and inquiry style labs

Biodegradation of tert-butyl alcohol (TBA) using biological granular activated carbon (bio-GAC)

ABSTRACT Tert-butyl alcohol (TBA), a metabolite of the gasoline additive methyl tert-butyl ether (MTBE), is a common groundwater contaminant encountered at petroleum remediation sites. This work explored the capability of YZ2, a novel pure culture, to completely degrade TBA aerobically in both batch studies and in continuous-flow columns containing biologically activated granular carbon (bio-GAC), simulating an ex-situ remedial system. YZ2 mineralized TBA from 0.5mM to 50mM, which is significantly higher than previously reported cultures. The level at which TBA limited the cellular activity was 40mM; however, mineralization still proceeded up to 50mM. Mineralization experiments showed almost 80% recovery of uniformly radiolabeled TBA as carbon dioxide. YZ2 growth and corresponding TBA oxidation rates within saturated activated carbon were compared with rates quantified in pure aqueous media; results demonstrate that GAC decreases oxidation kinetics for TBA. Batch studies quantified the kinetics of abiotic TBA sorption to activated carbon versus biological TBA oxidation using bio-GAC to compare the rates and efficiencies of physical removal processes to biological strategies. Data demonstrate that adsorption may be more efficient at high TBA concentration. In addition, pH levels increased to as high as 10.2 once activated carbon was added to solutions containing TBA, which inhibited microbial growth. The continuous-flow bio-GAC columns mimicked a field bio-GAC unit and focused on different potential inoculation strategies and the long-term capabilities of YZ2 to degrade TBA as a continuous culture. Current data indicate lower effluent TBA concentrations within the bio-GAC column for 70 days, compared to a sterile GAC control column. However, the overall stoichiometry of the mineralization pathway indicates that dissolved oxygen concentrations in influent water may limit TBA degradation in the bio-GAC column, preventing complete degradation. We are using these data to develop a strategy for biological regeneration of GAC, which may be the most effective use of inoculated, TBA degrading cultures

Reliability modelling of PEM fuel cells with hybrid Petri nets

In this paper, a novel model for dynamic reliability analysis of a PEM fuel cell system is developed using Modelica language in order to account for multi-state dynamics and aging. The modelling approach constitutes the combination of physical and stochastic sub-models with shared variables. The physical model consist of deterministic calculations of the system state described by variables such as temperature, pressure, mass flow rates and voltage output. Additionally, estimated component degradation rates are also taken into account. The non-deterministic model, on the other hand, is implemented with stochastic Petri nets which represent different events that can occur at random times during fuel cell lifetime. A case study of effects of a cooling system on fuel cell performance was investigated. Monte Carlo simulations of the process resulted in a distribution of system parameters, thus providing an estimate of best and worst scenarios of a fuel cell lifetime

‘They Think They Know Us Better’: Aboriginal Experiences of Education, Health and Employment in Contemporary South Australia

The annual reports released by the Australian Government over the past ten years indicate that little progress has been made to address the gap in equality between Aboriginal and non-Aboriginal Australians. It is in this context that this research adopts an ethnographical approach, and echoes the post-colonial turn in anthropology by placing the primary importance on the views of the Aboriginal Australians themselves and thus, allowing thick descriptions to be developed. This research places the voices of Aboriginal Australians at the centre of it, to understand their lived experiences within education, health and employment, which in turn identifies factors that impact the efforts of closing the gap in equality. Members of two Aboriginal communities in South Australia provided their in-depth perspectives, opinions and experiences about education, health and employment, while grounded theory helped to identify key factors impacting on these, namely the inclusion or exclusion of Aboriginal Australians in contemporary society and politics, the fragmentation of trust between Aboriginal and non-Aboriginal Australians, and the importance of Aboriginal culture. The lived experiences of Aboriginal Australians provide examples and important explanations of how services and initiatives within education, health and employment are received, and highlight how they are interconnected in their everyday lives. The findings show that although current social services and initiatives are not necessarily failing to address the issues they target, the lived experiences of some Aboriginal Australians reflect that it is the fractious relationships between Aboriginal Australians, the Australian Government and wider Australian society that have a direct impact on their success. The research reveals that Aboriginal Australians’ reluctance to accept and access some health, education and employment services is a key problem, which results in the ineffectiveness of these services. This thesis illustrates why some services and initiatives available to the communities are not as effective as others, and suggests that Aboriginal culture is a significant underpinning factor present in successful services and initiatives, but less evident in those considered ineffective. The inclusion of the actual voices of members of two Aboriginal communities in South Australia helps to highlight key attributes of effective services and initiatives, which have enabled possible suggestions for improving the lived experiences of Aboriginal Australians, which in turn support the efforts in closing the gap in equality

Influence of chronic L-DOPA treatment on immune response following allogeneic and xenogeneic graft in a rat model of Parkinson's disease

Although intrastriatal transplantation of fetal cells for the treatment of Parkinson’s disease had shown encouraging results in initial open-label clinical trials, subsequent double-blind studies reported more debatable outcomes. These studies highlighted the need for greater preclinical analysis of the parameters that may influence the success of cell therapy. While much of this has focused on the cells and location of the transplants, few have attempted to replicate potentially critical patient centered factors. Of particular relevance is that patients will be under continued L-DOPA treatment prior to and following transplantation, and that typically the grafts will not be immunologically compatible with the host. The aim of this study was therefore to determine the effect of chronic L-DOPA administered during different phases of the transplantation process on the survival and function of grafts with differing degrees of immunological compatibility. To that end, unilaterally 6-OHDA lesioned rats received sham surgery, allogeneic or xenogeneic transplants, while being treated with L-DOPA before and/or after transplantation. Irrespective of the L-DOPA treatment, dopaminergic grafts improved function and reduced the onset of L-DOPA induced dyskinesia. Importantly, although L-DOPA administered post transplantation was found to have no detrimental effect on graft survival, it did significantly promote the immune response around xenogeneic transplants, despite the administration of immunosuppressive treatment (cyclosporine). This study is the first to systematically examine the effect of L-DOPA on graft tolerance, which is dependent on the donor-host compatibility. These findings emphasize the importance of using animal models that adequately represent the patient paradigm

Properties of the signal mode in the polariton optical parametric oscillator regime

Theoretical analyses of the polariton optical parametric oscillator (OPO) regime often rely on a mean-field approach based on the complex Gross-Pitaevskii equations in a three-mode approximation, where only three momentum states, the signal, pump, and idler, are assumed to be significantly occupied. This approximation, however, lacks a constraint to uniquely determine the signal and idler momenta. In contrast, multimode numerical simulations and experiments show a unique momentum structure for the OPO states. In this work we show that an estimate for the signal momentum chosen by the system can be found from a simple analysis of the pump-only configuration. We use this estimate to investigate how the chosen signal momentum depends on the properties of the drive