User Behavior and Decision Making: The role of decisional Guidance in Decision Support

The very nature of decision support systems (DSS) is to guide and support the user. Yet decisional guidance has surprisingly not dominated empirical DSS research. In this research we examine the role of decisional guidance in decision support. We postulate that the effect of decisional guidance on decision outcomes is mediated by the subjective experience of the user in interacting with the DSS. Furthermore we develop a theoretical and empirical analysis of the different role decisional guidance plays for users of different levels of domain expertise: novices and experienced (but not expert) practitioners. Using a purpose built experimental platform with 135 subjects we find the effects on decisional guidance on perceptions of the DSS and confidence in decision outcomes varies interactively between type of guidance (informative versus suggestive) and level of expertis

Modeling the electromagnetic properties of the SCUBA-2 detectors

SCUBA-2 is the next-generation replacement for SCUBA (Sub-millimetre Common User Bolometer Array) on the James Clerk Maxwell Telescope. Operating at 450 and 850 microns, SCUBA-2 fills the focal plane of the telescope with fully-sampled, monolithic bolometer arrays. Each SCUBA-2 pixel uses a quarter-wave slab of silicon with an implanted resistive layer and backshort as an absorber and a superconducting transition edge sensor as a thermometer. In order to verify and optimize the pixel design, we have investigated the electromagnetic behaviour of the detectors, using both a simple transmission-line model and Ansoft HFSS, a finite-element electromagnetic simulator. We used the transmission line model to fit transmission measurements of doped wafers and determined the correct implant dose for the absorbing layer. The more detailed HFSS modelling yielded some unexpected results which led us to modify the pixel design. We also verified that the detectors suffered little loss of sensitivity for off-axis angles up to about 30 degrees.Comment: 13 pages, 14 figures, SPIE Glasgow 21-25 June 2004, Conference 549

Do bedroom screens and the mealtime environment shape different trajectories of child overweight and obesity? Research using the Growing Up in Scotland study

Objective: To investigate how mealtime setting, mealtime interaction and bedroom screens are associated with different trajectories of child overweight and obesity, using a population sample. Methods: Growth mixture modelling used data from children in the Growing Up in Scotland Study born in 2004/5 (boys n = 2085, girls n = 1991) to identify trajectories of overweight or obesity across four time points, from 46 to 122 months. Using data from children present at all sweeps, and combining sexes (n = 2810), mutually adjusted associations between primary exposures (mealtime setting, mealtime interaction and bedroom screens) and trajectory class were explored in multinomial models; controlling for early life factors, household organisation and routines, and children’s diet patterns, overall screen use, physical activity and sleep. Results: Five trajectories were identified in both sexes: Low Risk (68% of sample), Decreasing Overweight (9%), Increasing Overweight (12%), High/Stable Overweight (6%) and High/Increasing Obesity (5%). Compared with the Low Risk trajectory, High/Increasing Obesity and High/Stable Overweight trajectories were characterised by early increases in bedroom screen access (respective relative risk ratios (RRR) and 95% confidence intervals: 2.55 [1.30–5.00]; 1.62 [1.01–2.57]). An informal meal setting (involving mealtime screen use, not eating in a dining area and not sitting at a table) characterised the High/Increasing Obesity and Increasing Overweight trajectories (respective RRRs compared with Low Risk trajectory: 3.67 [1.99–6.77]; 1.75 [1.17–2.62]). Positive mealtime interaction was associated with membership of the Increasing Overweight trajectory (RRR 1.64 [1.13–2.36]). Conclusion: Bedroom screen access and informal mealtime environments were associated with higher-risk overweight and obesity trajectories in a representative sample of Scottish children, after adjusting for a wide range of confounders. Findings may challenge the notion that positive mealtime interaction is protective. Promoting mealtimes in a screen-free dining area and removing screens from bedrooms may help combat childhood obesity

Coparenting and parenting pathways from the couple relationship to children's behavior problems

Although an extensive literature has linked couple conflict with the development of children’s externalizing behavior problems, longer term protective effects of positive dimensions of couple relationships on children’s externalizing behavior remain understudied, particularly in relation to underlying mechanisms. Supportiveness in the dyadic couple relationship may enhance mothers’ and fathers’ individual parenting skills and protect against children’s behavior problems, but the contribution of co-parenting (couples’ support for one another’s individual parenting) remains unclear. This observational study investigated associations between couple supportiveness in children’s infancy and middle childhood externalizing problems, exploring pathways involving coparenting and/or mothers’ and fathers’ individual parenting using data from the UK Millennium Cohort Study (MCS, N = 5779) and the US Fragile Families and Child Wellbeing Study (FFS, N = 2069). Couple supportiveness was associated with reduced externalizing problems 8-10 years later (standardized betas: MCS:-.13, FFS: -.11, both p <.001). Much of this effect (60% MCS, 55% FFS) was attributable to coparenting and parenting when children were aged 3-5 years. Pathways from couple supportiveness involving negative parenting were stronger than those via positive parenting, pathways via mothers’ parenting were stronger than those via fathers’ parenting, and there were pathways via coparenting alone (without affecting parenting). Pathways involving coparenting were similar in magnitude (MCS), or larger (FFS), than those involving parenting alone. Consistent findings across different population samples suggest that helping parents to support one another in co-parenting, as well as develop their individual parenting skills, may lessen the longer term impact of couple relationship problems during early childhood

Specifying and Monitoring Market Mechanisms Using Rights and Obligations

We provide a formal scripting language to capture the semantics of market mechanisms. The language is based on a set of well-defined principles, and is designed to capture an agent’s rights, as derived from property, and an agent’s obligations, as derived from restrictions placed on its actions, either voluntarily or as a consequence of other actions. Rights and obligations are viewed as first-class goods, from which we define fundamental axioms about well-functioning market-oriented worlds. Coupled with the scripting language is a run-time system that is able to monitor and enforce rights and obligations. Our treatment extends to represent a variety of market mechanisms, ranging from simple two-agent single-good exchanges to complicated combinatorial auctions.Engineering and Applied Science

ab initio modeling of yttria stabilised zirconia for solid oxide fuel cells

Fuel cells are electrochemical devices that convert chemical fuels directly into electricity, heat, and waste products with higher efficiencies than many conventional combustion technologies. Fuel cells have already found applications in automotive and domestic applications, where their high efficiencies offer potential reductions in CO2 emissions as well as energy savings. A promising technology is the solid oxide fuel cell (SOFC), which typically runs at temperatures between 500 - 1000C, and can convert hydrogen rich gases, such as methane, directly into heat and electricity. This thesis presents work on developing improved atomistic models of yttria stabilised zirconia (YSZ), which is used as a catalyst support and electrolyte material in a solid oxide fuel cell. The catalyst, YSZ, and a gas phase containing fuel molecules, meet at the anode to form the anode triple phase boundary (TPB) in an SOFC. The anode TPB is the site at which fuel molecules undergo electrochemical oxidation, a process that releases electrons and waste products. Unfortunately the anode is susceptible to poisoning and damage through detrimental chemical reactions which can lead to carbon deposition and sulphur poisoning. A long term aim for the field of SOFC catalysis is to understand these reactions and design improved catalysts which are resistant to contamination processes. However, to date, the detailed mechanisms involved in these reactions have not been established; even the mechanism for the oxidation of hydrogen at the anode TPB is fiercely debated. For these reasons, there is interest in developing atomistic models of the anode TPB to investigate the thermodynamics of possible reaction paths. Modeling the anode TPB is dependant on many factors including: materials, surface structure, interfaces, distribution of local defects. A detailed knowledge of the YSZ surface chemistry is currently inhibited by a poor understanding of the distribution and local atomistic structure of the dopant Y3+ ions and oxygen vacancies in the bulk crystal and at the surfaces. In this thesis, a comprehensive search for low energy defect structures using a combined classical modeling and density functional theory (DFT) approach is used to identify the low energy defect structures of 3.2mol% YSZ. 3.2mol% YSZ is chosen as the limit of low dopant concentration and as a simple system to investigate, avoiding the the combinatorial complexity of higher dopant concentrations and defect-defect interactions. Through analysis of energetics computed using; the best available empirical potential model, point charges, DFT, and local strain energy estimated in the harmonic approximation, we examine the main chemical and physical interactions that determine the low energy structures. It is found that the empirical potential model reproduces a general trend of increasing DFT energetics across a series of locally strain relaxed structures, but is unreliable both as it predicts some incorrect low energy structures, and because it finds some meta-stable structures to be unstable. A better predictor of low energy defect structures is the total electrostatic energy of a simple point charge model calculated at the unrelaxed geometries of the defects. In addition, the strain relaxation energy is substantial, and is estimated effectively in the harmonic approximation to the imaginary phonon modes of cubic zirconia (c-ZrO2), but it is not a determining factor for the relative stabilities of low energy defect structures. These results allow us to propose a simple method for identifying low energy YSZ defect structures. The findings from the studies of bulk 3.2mol% YSZ are used to establish the low energy structures of a 3.2mol% YSZ (111) surface model. After initially demonstrating that a slab model, much larger than that used in previous DFT studies is required to obtain a converged surface energy, the energetic preference for yttrium to segregate to the (111) surface is investigated. After establishing that yttrium indeed segregates to the (111) surface, we compute the DFT energies of 20 low energy symmetry inequivalent surface structures, and identify the preferential defect configurations and surface chemistry sites. In addition, the DFT energy of the low energy NN structure proposed by Reaxff modeling is computed. It is shown that this structures is significantly higher in energy than our minimum energy structure, which has NNN geometry. This highlights the need for large scale DFT calculations in understanding the YSZ (111) surface structure. Having obtained atomistic structures for the surface reaction sites, water dissociation onto the lowest energy YSZ (111) surface is investigated. It is shown that it is preferable for water to associatively adsorb to the YSZ surface, and this is optimal when water adsorbs to the yttrium site. Dissociative adsorption of water is only possible over zirconium sites with the process generally being endothermic. Some exothermic paths for dissociative adsorption exist, however there are large energy barriers to the process. Associative adsorbtion to the surface yttrium site is the global minimum of the system, and yttrium sites appear to act as a trap for water molecules. Finally, the methodology developed in previous sections is used to investigate the 6.7mol% YSZ system, which is closer to the Y2O3 dopant concentration used in most commercial SOFCs (8 - 10 mol%). It is found that, whereas the electrostatic energy of the unrelaxed structures calculated using a point charge model was a good predictor of the likely low energy 3.2mol% defect structures, it is a poor predictor of the likely low energy 6.7mol% defect structures. In addition, while it was found that the best available Born-Mayer-Huggins potential model recreated general trends in DFT energies at 3.2mol%, it completely fails to reproduce DFT energy differences at 6.7mol%. In the absence of an easy to calculate, reliable predictor of the likely low energy DFT defect structures, we correlate the formation energies of the structures to simple geometric parameters. We perform an exhaustive search on 2857 symmetry inequivalent structures, characterising every structure in terms of intuitive quantities, such as: vacancy - vacancy separation, the average vacancy - Y3+ interatomic separation, the average Y3+ - Y3+ interatomic speration, the surface area occupied by the defect cluster, and the volume of the defect cluster. It is possible to explain the electrostatic formation energies of the defects in terms of intuitive attractive and repulsive forces and to find weak trends between the geometric descriptors and the final relaxed DFT energies, however, without an extensive database of fully relaxed DFT energies, it is hard to determine the statistical meaning of these results. This result highlights the combinatorial complexity of the 6.7mol% system and establishes the need for further large scale DFT calculations on the 6.7 mol% system.Open Acces

Virtual Battlespace Scenario Encoding for Reuse, Phase I Report

The United States Army and United States Marine Corps employ the Virtual Battlespace 2 (VBS2) commercial game for small unit training. Each service has significant investment in training scenarios constructed using VBS2 tools and conforming to the vendor's particular data formats. To move toward improved interoperability, to gain greater fiscal flexibility in addressing the statutory intent for open competition and affordability, and to protect the investment made in models, terrain, and other elements of training scenarios that are separate and distinct from the virtual and gaming environments in which the simulation executes, open standards need to be applied in place of proprietary commercial off-the-shelf architectures. In the current ( and foreseeable) environment of constrained budgets, it is ever more critical that the services protect and enhance their investments in simulation systems used for training and other purposes. Expanding capabilities for open scenario interchange will improve scenario reuse while creating greater opportunities for simulation data interchange and open competition for future gaming capabilities. The Extensible Markup Language (XML) is a wide-spread approach to describing data format and content to support efficient data processing and data interchange across systems. This report describes initial application of XML technologies to the representation of VBS2 scenario data, demonstrating feasibility for the capture and exchange of VBS2 scenario data. The report provides a plan of action for a follow-on phase of the effort to expand the representation and for use with other XML-based standards, such as the Military Scenario Definition Language (MSDL), to create opportunities for broader interchange of scenario data across a variety of combat simulations.Commander, Marine Corps Systems Command (DC SIAT)Marine Corps Systems Command, Modeling and Simulation OrganizationApproved for public release; distribution is unlimited