The objective of this investigation has been to develop and evaluate techniques which are appropriate to the modelling and simulation of biological reaction system behaviour. The model used as the basis for analysis of modelling and simulation techniques is a reduced version of the biological model proposed by the IAWPRC Task Group for mathematical modell ing in wastewater treatment design. This limited model has the advantage of being easily manageable in terms of analysis and presentation of the simulation techniQues whilst at the same time incorporating a range of features encountered with biological growth applications in general. Because a model may incorporate a number of different components and large number of biological conversion processes, a convenient method of presentation was found to be a matrix format. The matrix representation ensures clarity as to what compounds, processes and react ion terms are to be incorporated and allows easy comparison of different models. In addition, it facilitates transforming the model into a computer program. Simulation of the system response first involves specifying the reactor configuration and flow patterns. With this information fixed, mass balances for each compound in each reactor can be completed. These mass balances constitute a set of simultaneous non-linear differential and algebraic eQuations which, when solved, characterise the system behaviour.

The intention of the project is to determine whether political elites have to discuss an issue using a specific emotional tone before the public and other political elites consider that issue a problem. Research has not yet demonstrated under what conditions elite rhetorical cues can heighten issue attention. Past studies have suggested that an increase in the absolute intensity of elite issue discussion can heighten perceptions of an issue as a problem. The problem with this notion is that within that absolute issue discussion, elites might simply be repeatedly saying conditions related to an issue are stable. They might also be presenting basic factual background information about an issue, a type of discussion unlikely to capture the interest of many in the political system. There has to be a specific type of cue that elites can offer to compel others in the political system to reconsider their outlook on issue salience. Derived from dual systems theories of emotion, the dissertation predicts that issue discussion that heightens feelings of anxiety increases the likelihood of an altered outlook on issue salience. To evaluate this prediction, time series statistical techniques are employed. The time series models evaluate whether prior change in the level of anxietybased cues by the president and the media predict changes in the level of attention the public offers to that issue. The same types of models evaluate whether this form of issue discussion by the president predicts issue dynamics of the media, and vice-versa. The several issues studied are crime, health care, poverty, and the environment. Information spanning thirty years is collected from presidential papers, general and ideological media newspaper coverage, and multiple public survey organizations. The findings suggest anxiety-based issue discussion does have the potential to guide issue attention. Prior changes in anxiety-based cues do predict future levels of attention the public provides to issues. A positive shift in anxiety cues by elites appears to have the capacity to increase public attention to issues. This increase though appears to be very small and abbreviated, suggesting limited effects. Elites do not appear to influence each other through anxiety cues.

Abstract The resilience, or sustainability, of an environmental system depends on key factors remaining within critical thresholds. Current approaches to assessing the condition and trend of environmental systems rely on expert knowledge of system performance and subjective interpretation. Computer simulation models of natural resource systems offer a way to integrate system properties, and ecological theory and relationships, with long-term climate and rainfall information to simulate system performance within a consistent framework. Financial accounting methods, such as balance sheets and ratio analysis, have been developed to assess overall businesses viability and offer a potential tool for assessing the sustainability of natural systems, providing key accounting principles and assumptions can be reasonably met. This thesis explores the integration of accounting and ecological theory in a balance sheet framework for sustainability accounting using non-financial terms with a view to contributing to the sustainable management of natural resources within dynamic systems. A generic approach to constructing environmental balance sheets was developed and tested at a range of scales (field to catchment). Sensitivity analysis of the models was used to determine key factors and critical thresholds relating to system resilience. These values were then used to construct the balance sheets. The current ratio was then used to identify if the system was being managed sustainably. A current ratio (assets/liabilities) greater than 1.0, derived from the balance sheet, was shown to denote more resilient, and hence sustainable, systems. Case studies used were wheat cropping in the Maranoa area of Queensland, Australia, and the Bonogin Valley in the Gold Coast, Queensland Australia The same approach to constructing balance sheets worked across all scales from farm to catchment. . The approach was then used to develop a sustainability assessment of the Coomera catchment of the Gold Coast to consider how natural resource management and urbanisation is affecting catchment resilience. A series of models was used to develop the accounts: a grazing systems model – SGS; a cropping systems model - APSIM-sugar; and an existing catchment hydrology and water quality model - EMSS. The approach demonstrated that sugarcane cropping systems within the catchment were not likely to be sustainable without significant input of nitrogen, but that the grazing systems were. Furthermore, the overall catchment was likely to be sustainable (2002). This finding is consistent with an independent field-based assessment of the catchment conducted by the Healthy Waterways Partnership of South East Queensland. The urban development anticipated in the catchment by 2020, did not appear to have a significant affect as measured by long-term trends in flow frequency and water quality. The use of ratio analysis provided a dimensionless variable that related to the resilience of a parcel of land or catchment. These values were able to be spatially integrated, using an area weighted median, to provide an overall estimate of resilience of land use for a farm or a catchment. However, it was considered simpler to model the catchment of interest as a whole rather than to combine ratios from a series of catchment sub-models. The availability of appropriate comprehensive systems models may prove a limitation for application to all land uses especially native bushland systems. However, the approach developed in this thesis provides a robust and consistent framework for exploring system resilience and sustainability in a way that can augment existing approaches to natural resource assessments of condition and trend.

The three-dimensional structure of a protein, formed as a result of amino-acid sequences folding into compact domains, is regarded as a key factor in its biological function. How and why proteins fold into specific topologies, remain the key focus of scientific research in the field of biophysics. By stripping down complex reactions down to the most basic elements, biophysicists aim to develop simplified models for biological phenomena such as antibody discrimination, viral fusion or self-assembly. Focusing on small model peptide systems, rather than the full proteins from which they were derived, was hoped to result in accurate structural measurements and provide a more transparent comparison between simulation and experiment. The aim of this research was therefore to investigate how accurate these models were when compared against experiment. Furthermore, while breaking down the complex biological phenomena into simple models, there was also a conscious effort to ensure that the models were representative of real biological systems, and a major focus was therefore aimed at determining whether any meaningful biomedical insight may be extrapolated from such models. Peptides found in hormones (human chorionic gonadotropin, luteinizing hormone), viruses (HIV) and amyloid diseases (transthyretin) were selected in order to probe a variety of questions in relation to the aforementioned biological phenomena. Namely, how the primary sequence influenced the three-dimensional structure (and thus its biological function), how its environment could influence such a confirmation, and how these systems aggregated. This doctoral study has made use of a combination of computer simulations and experimental techniques to investigate a selection of biologically relevant peptides; utilising classical atomistic molecular dynamics (MD) simulations to characterise the free-energy landscapes of the chosen peptides, and compare these findings with the secondary structure content predicted by spectroscopic methods such as circular dichroism and infrared spectroscopy. The peptide systems studied within, were found to be characterised by rugged free-energy landscapes unlike their protein counterparts (defined by singular, deep minima). Furthermore, these landscapes were found to be highly plastic and sensitive to changes in the local environment.

Regulated rivers provide opportunities to improve habitat quality by managing the times, locations, and magnitudes of reservoir releases and diversions across the watershed. To identify these opportunities, managers select priority species and determine when, where, and how to allocate water between competing human and environmental users in the basin. Systems models have been used to recommend allocation of water between species. However, many models consider species’ water needs as constraints on instream flow that is managed to maximize human beneficial uses. Many models also incorporate uncertainty in the system and report an overwhelmingly large number of management alternatives. This dissertation presents three new novel models to recommend the allocation of water and money to improve habitat quality. The new models also facilitate communicating model results to managers and to the public. First, a new measurable and observable habitat metric quantifies habitat area and quality for priority aquatic, floodplain, and wetland habitat species. The metric is embedded in a systems model as an ecological objective to maximize. The systems model helps managers to identify times and locations at which to apply scarce water to most improve habitat area and quality for multiple competing species. Second, a cluster analysis approach is introduced to reduce large dimensional uncertainty problems in habitat models and focus management efforts on the important parameters to measure and monitor more carefully. The approach includes manager preferences in the search for clusters. It identifies a few, easy-to-interpret management options from a large multivariate space of possible alternatives. Third, an open-access web tool helps water resources modelers display model outputs on an interactive web map. The tool allows modelers to construct node-link networks on a web map and facilitates sharing and visualizing spatial and temporal model outputs. The dissertation applies all three studies to the Lower Bear River, Utah, to guide ongoing habitat conservation efforts, recommend water allocation strategies, and provide important insights on ways to improve overall habitat quality and area.

M. Coderch ... [et al.]. / Bibliography: leaf 6. / "September, 1981." / Supported in part by the DOE under Grant ET-76-C-01-2295

by Michael Athans. / Bibliography: p. 18. / "November 1981." / Supported by the Office of Naval Research Contract ONR/N00014-77-C-0532 (NR041-519) AFOSR Contract 80-0229 Naval Electronic Systems Command Contract N00039-80-C-0390 Naval Electronic Systems Command Contract N00039-81-C-0243

Licentiatavhandling (sammanfattning) Ultuna : Sveriges lantbruksuniversitet, 2006. / Härtill 2 uppsatser.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 93-110.

by Ramakrishna Akella, Yong Choong and Stanley B. Gershwin. / "February, 1984." / Bibliography: p. 29. / NASA Grant No. NAG1-2