The Anatomy of Virtual Manipulative Apps: Using Grounded Theory to Conceptualize and Evaluate Educational Apps that Contain Virtual Manipulatives

This exploratory qualitative study used grounded theory to investigate the anatomy of educational apps that contain virtual manipulatives. For this study 100 virtual manipulatives within educational apps designed for the iPad were observed by the researcher in order to expand the explanations of and build theory about virtual manipulatives within apps. Affordance theory was used to frame all six phases of the study in which the researcher identified virtual manipulatives situated within educational apps, conducted observer-as-participant structured and unstructured observations, analyzed component data including field notes and memos using open and axial coding, created a conceptual framework, developed an evaluation tool prototype to evaluate virtual manipulatives within educational apps, and used the evaluation tool prototype to evaluate additional virtual manipulatives within educational apps. The constant comparative method of open and axial coding was used to analyze the observation data that included field notes, memos, and video recordings. This indepth qualitative analysis led to the emergence of six study results concerning the components and relationships within educational apps that contain virtual manipulatives. The results revealed that: (1) virtual manipulatives within apps are comprised of two components: dynamic mathematical objects and features; (2) there are three distinct types of dynamic mathematical objects; (3) there are eight categories of features; (4) within one virtual manipulative there can be one or multiple objects; (5) varying relationships can exist among the dynamic object and the features within a virtual manipulative; and (6) varying relationships can exist among the virtual manipulatives within an education app in terms of the number, type, and ways the user proceeds. A conceptual framework was also developed during the study to illustrate the components and relationships that emerged from the analysis and to serve as the basis for the development of an evaluation tool prototype to evaluate educational apps that contain virtual manipulatives. The components, relationships, framework, and evaluation tool prototype developed during this study advance the literature on virtual manipulatives and provide researchers with a common language to evaluate these apps

Bedded Pack Management System Case Study

Agribusiness, Agricultural Finance, Farm Management,

A COBRA/TRAC, Best-Estimate Analysis of a Large-Break Accident in a PWR Equipped with Upper Head Injection

This report is about the Best-Estimate Analysis of a Large-Break Accident in a PWR Equipped with Upper Head Injection. It also documents about the simulation of a double ended (200 percent), cold leg break, loss-of-coolant accident in a PWR Equipped with Upper Head Injection

A COBRA/TRAC, Best-Estimate Analysis of a Large-Break Accident in a PWR Equipped with Upper Head Injection

This report is about the Best-Estimate Analysis of a Large-Break Accident in a PWR Equipped with Upper Head Injection. It also documents about the simulation of a double ended (200 percent), cold leg break, loss-of-coolant accident in a PWR Equipped with Upper Head Injection

Practical Implementation of a General Numerical Lifting-Line Method

A general numerical lifting-line method provides corrections to overcome the singularities inherent in the lifting-line downwash integrals in certain cases. These singularities have previously limited the scope of lifting-line theory to straight wings not in sideslip; in all other cases, more traditional numerical approaches to solving Prandtl\u27s hypothesis fail to grid converge. However, this general numerical lifting-line method grid converges even for swept wings and wings in sideslip. In the current work, we apply the general numerical lifting-line method to any number of wings with arbitrary geometry. We also provide a dimensional derivation of the basic general numerical lifting-line equations and discuss how airfoil section properties can be corrected for sweep. We develop a linearized system of equations and a nonlinear improvement method to solve the general numerical lifting-line equations. Results show that placing the lifting-line on the wing locus of aerodynamic centers, as done by others, may not yield the most accurate results. Comparisons with published data reveal that the general numerical lifting-line method can accurately predict the lift distribution for swept wings

67/12/12 Oral Arguments before the US Supreme Court

Tuesday, December 12, 1967 oral arguments before the United States Supreme Court

Dynamics of high viscosity contrast confluent microfluidic flows

The laminar nature of microfluidic flows is most elegantly demonstrated via the confluence of two fluids forming two stable parallel flows within a single channel meeting at a highly stable interface. However, maintenance of laminar conditions can become complicated when there is a large viscosity contrast between the neighbouring flows leading to unique instability patterns along their interface. Here, we study the dynamics of high viscosity contrast confluent flows - specifically a core flow made of highly viscous glycerol confined by sheath flows made of water within a microfluidic flow focusing system. Our experiments indicate the formation of tapered core structures along the middle of the channel. Increasing the sheath flow rate shortens the tapered core, and importantly induces local instability patterns along the interface of core-sheath flows. The dynamics of such tapered core structures is governed by the intensity of instability patterns and the length of the core, according to which the core structure can experience stable, disturbed, broken or oscillated regimes. We have studied the dynamics of tapered core structures under these regimes. In particular, we have analysed the amplitude and frequency of core displacements during the broken core and oscillating core regimes, which have not been investigated before

Resistively-limited current sheet implosions in planar anti-parallel (1D) and null-point containing (2D) magnetic field geometries

Implosive formation of current sheets is a fundamental plasma process. Previous studies focused on the early time evolution, while here our primary aim is to explore the longer-term evolution, which may be critical for determining the efficiency of energy release. To address this problem we investigate two closely-related problems, namely: (i) 1D, pinched anti-parallel magnetic fields and (ii) 2D, null point containing fields which are locally imbalanced ('null-collapse' or 'X-point collapse'). Within the framework of resistive MHD, we simulate the full nonlinear evolution through three distinct phases: the initial implosion, its eventual halting mechanism, and subsequent evolution post-halting. In a parameter study, we find the scaling with resistivity of current sheet properties at the halting time is in good agreement - in both geometries - with that inferred from a known 1D similarity solution. We find that the halting of the implosions occurs rapidly after reaching the diffusion scale by sudden Ohmic heating of the dense plasma within the current sheet, which provides a pressure gradient sufficient to oppose further collapse and decelerate the converging flow. This back-pressure grows to exceed that required for force balance and so the post-implosion evolution is characterised by the consequences of the current sheet `bouncing' outwards. These are: (i) the launching of propagating fast MHD waves (shocks) outwards and (ii) the width-wise expansion of the current sheet itself. The expansion is only observed to stall in the 2D case, where the pressurisation is relieved by outflow in the reconnection jets. In the 2D case, we quantify the maximum amount of current sheet expansion as it scales with resistivity, and analyse the structure of the reconnection region which forms post-expansion, replete with Petschek-type slow shocks and fast termination shocks

An automated optofluidic biosensor platform combining interferometric sensors and injection moulded microfluidics

A primary limitation preventing practical implementation of photonic biosensors within point-of-care platforms is their integration with fluidic automation subsystems. For most diagnostic applications, photonic biosensors require complex fluid handling protocols; this is especially prominent in the case of competitive immunoassays, commonly used for detection of low-concentration, low-molecular weight biomarkers. For this reason, complex automated microfluidic systems are needed to realise the full point-of-care potential of photonic biosensors. To fulfil this requirement, we propose an on-chip valve-based microfluidic automation module, capable of automating such complex fluid handling. This module is realised through application of a PDMS injection moulding fabrication technique, recently described in our previous work, which enables practical fabrication of normally closed pneumatically actuated elastomeric valves. In this work, these valves are configured to achieve multiplexed reagent addressing for an on-chip diaphragm pump, providing the sample and reagent processing capabilities required for automation of cyclic competitive immunoassays. Application of this technique simplifies fabrication and introduces the potential for mass production, bringing point-of-care integration of complex automated microfluidics into the realm of practicality. This module is integrated with a highly sensitive, label-free bimodal waveguide photonic biosensor, and is demonstrated in the context of a proof-of-concept biosensing assay, detecting the low-molecular weight antibiotic tetracycline

Randomised trials comparing different healthcare settings : an exploratory review of the impact of pre-trial preferences on participation, and discussion of other methodological challenges

BACKGROUND: We recently published a systematic review of different healthcare settings (such as outpatient, community or home) for administering intravenous chemotherapy, and concluded that performing conventionally designed randomised trials was difficult. The main problems were achieving adequate trial accrual rates and recruiting a study population which adequately represented the target population of interest. These issues stemmed from the fact that potential participants may have had pre-trial perceptions about the trial settings they may be allocated; such preferences will sometimes be strong enough for patients to decline an invitation to participate in a trial. A patient preference trial design (in which patients can choose, or be randomised to, an intervention) may have obviated these recruitment issues, although none of the trials used such a design. METHODS: In order to gain a better understanding of the broader prevalence and extent of these preference issues (and any other methodological challenges), we undertook an exploratory review of settings trials in any area of healthcare treatment research. We searched The Cochrane Library and Google Scholar and used snowballing methods to identify trials comparing different healthcare settings. RESULTS: Trial accrual was affected by patient preferences for a setting in 15 of the 16 identified studies; birth setting trials were the most markedly affected, with between 68 % and 85 % of eligible women declining to participate specifically because of preference for a particular healthcare setting. Recruitment into substance abuse and chemotherapy setting studies was also notably affected by preferences. Only four trials used a preference design: the proportion of eligible patients choosing to participate via a preference group ranged from between 33 % and 67 %. CONCLUSIONS: In trials of healthcare settings, accrual may be seriously affected by patient preferences. The use of trial designs which incorporate a preference component should therefore strongly be considered. When designing such trials, investigators should consider settings to be complex interventions, which are likely to have linked components which may be difficult to control for. Careful thought is also needed regarding the choice of comparator settings and the most appropriate outcome measures to be used