Evaluating Hank, a cognitive modelling language for psychologists

Hank is a visual programming language devised specically for the use of cognitive psychologists rather than computer programmers. This paper introduces an eighteen month evaluation project on the use of Hank. This project began on November the 1st 1998, the initial findings and planned evaluation programme will be presented at the workshop in January

An application of formal semantics to student modelling : an investigation in the domain of teaching Prolog

This thesis reports on research undertaken in an exploration of the use of formal semantics for student modelling in intelligent tutoring systems. The domain chosen was that of tutoring programming languages and within that domain Prolog was selected to be the target language for this exploration. The problem considered is one of how to analyse students' errors at a level which allows diagnosis to be more flexible and meaningful than is possible with the 'mal-rules' and 'bugcatalogue' approach of existing systems. The ideas put forward by Robin Milner [1980] in his Calculus of Communicating Systems (CCS) form the basis of the formalism which is proposed as a solution to this problem. Based on the findings of an empirical investigation, novices' misconceptions of control flow in Prolog was defined as a suitable area in which to explore the application of this solution. A selection of Prolog programs used in that investigation was formally described in terms of CCS. These formal descriptions were used by a production rule system to generate a number of the incomplete or faulty models of Prolog execution which were identified in the first empirical study. In a second empirical study, a machine-analysis tool, designed to be part of a diagnostic tutoring module, used these models to diagnose students' misconceptions of Prolog control flow. This initial application of CCS to student modelling showed that the models of Prolog execution generated by the system could be used successfully to detect students' misunderstandings. Results from the research reported here indicate that the use of formal semantics to model programming languages has a useful contribution to make to the task of student modelling

Online educational counselling for students with special needs: Building rapport

This paper reports the findings from a study that investigated the effects of providing online counselling for undergraduate students with long‐term health problems. Issues associated with learning at a distance for such students include fatigue, manual dexterity, academic and social isolation, together with a need for better interactive communication with support agencies (Debenham, 1996a). The results of a feasibility study undertaken in 1996 suggested that for students with special needs personal rapport with their educational counsellor is considered important for problems to be aired and addressed (Debenham, 1998a). This raises interesting questions relating to how such rapport can be developed using computer‐mediated communication (CMC). Participants in the study reported appreciation of a small amount of informal contact with the counsellor in a closed peer‐group conference; this conference is described in Debenham (1996b). Building on this finding, a main study was undertaken which was modified by the addition of a counselling topic ‐ a ‘Virtual Study’ for the counsellor ‐ within this conference area (Debenham, 1998b). The counsellor was encouraged to participate informally in the other student‐led topics. This added a group dimension to the study. The results are encouraging: increased levels of motivation and enjoyment of the study process were reported by more than three‐quarters of the sample and in the degree of autonomy by more than half the sample. These findings throw light on the support of students with special needs and also contribute to the development of knowledge in the wider fields of academic advising and the use of CMC in distance education

Theranostic pretargeted radioimmunotherapy of colorectal cancer xenografts in mice using picomolar affinity 86Y- or 177Lu-DOTA-Bn binding scFv C825/GPA33 IgG bispecific immunoconjugates

Purpose: GPA33 is a colorectal cancer (CRC) antigen with unique retention properties after huA33-mediated tumor targeting. We tested a pretargeted radioimmunotherapy (PRIT) approach for CRC using a tetravalent bispecific antibody with dual specificity for GPA33 tumor antigen and DOTA-Bn–(radiolanthanide metal) complex. Methods: PRIT was optimized in vivo by titrating sequential intravenous doses of huA33-C825, the dextran-based clearing agent, and the C825 haptens [superscript 177]Lu-or [superscript 86]Y-DOTA-Bn in mice bearing the SW1222 subcutaneous (s.c.) CRC xenograft model. Results: Using optimized PRIT, therapeutic indices (TIs) for tumor radiation-absorbed dose of 73 (tumor/blood) and 12 (tumor/kidney) were achieved. Estimated absorbed doses (cGy/MBq) to tumor, blood, liver, spleen, and kidney for single-cycle PRIT were 65.8, 0.9 (TI 73), 6.3 (TI 10), 6.6 (TI 10), and 5.3 (TI 12), respectively. Two cycles of PRIT (66.6 or 111 MBq [superscript 177]Lu-DOTA-Bn) were safe and effective, with a complete response of established s.c. tumors (100 – 700 mm³) in nine of nine mice, with two mice alive without recurrence at >140 days. Tumor log kill in this model was estimated to be 2.1 – 3.0 based on time to 500-mm³ tumor recurrence. In addition, PRIT dosimetry/diagnosis was performed by PET imaging of the positron-emitting DOTA hapten [superscript 86]Y-DOTA-Bn. Conclusion: We have developed anti-GPA33 PRIT as a triplestep theranostic strategy for preclinical detection, dosimetry, and safe targeted radiotherapy of established human colorectal mouse xenografts.National Institute of Mental Health (U.S.) (Grant R01-CA-101830

Targeting of radiolabeled J591 antibody to PSMA-expressing tumors: optimization of imaging and therapy based on non-linear compartmental modeling

BACKGROUND: We applied a non-linear immunokinetic model to quantitatively compare absolute antibody uptake and turnover in subcutaneous LNCaP human prostate cancer (PCa) xenografts of two radiolabeled forms of the humanized anti-prostate-specific membrane antigen (PSMA) monoclonal antibody J591 ((124)I-J591 and (89)Zr-J591). Using the model, we examined the impact of dose on the tumor and plasma positron emission tomography (PET)-derived time-activity curves. We also sought to predict the optimal targeting index (ratio of integrated-tumor-to-integrated-plasma activity concentrations) for radioimmunotherapy. METHODS: The equilibrium rates of antibody internalization and turnover in the tumors were derived from PET images up to 96 h post-injection using compartmental modeling with a non-linear transfer rate. In addition, we serially imaged groups of LNCaP tumor-bearing mice injected with (89)Zr-J591 antibody doses ranging from antigen subsaturating to saturating to examine the suitability of using a non-linear approach and derived the time-integrated concentration (in μM∙hours) of administered tracer in tumor as a function of the administered dose of antibody. RESULTS: The comparison of (124)I-J591 and (89)Zr-J591 yielded similar model-derived values of the total antigen concentration and internalization rate. The association equilibrium constant (k(a)) was twofold higher for (124)I, but there was a ~tenfold greater tumoral efflux rate of (124)I from tumor compared to that of (89)Zr. Plots of surface-bound and internalized radiotracers indicate similar behavior up to 24 h p.i. for both (124)I-J591 and (89)Zr-J591, with the effect of differential clearance rates becoming apparent after about 35 h p.i. Estimates of J591/PSMA complex turnover were 3.9–90.5 × 10(12) (for doses from 60 to 240 μg) molecules per hour per gram of tumor (20 % of receptors internalized per hour). CONCLUSIONS: Using quantitative compartmental model methods, surface binding and internalization rates were shown to be similar for both (124)I-J591 and (89)Zr-J591 forms, as expected. The large difference in clearance rates of the radioactivity from the tumor is likely due to differential trapping of residualizing zirconium versus non-residualizing iodine. Our non-linear model was found to be superior to a conventional linear model. This finding and the calculated activity persistence time in tumor have important implications for radioimmunotherapy and other antibody-based therapies in patients

Cognitive Modelling for Psychology Students: The Evaluation of a Pragmatic Approach to Computer Programming for Non Programmers

Cognitive modelling is a common component of undergraduate psychology degree courses. However, the problem with cognitive modelling is that students must first learn how to program a computer before they are able to practice cognitive modelling and thereby, appreciate for themselves the contribution cognitive modelling makes to psychology. Learning to program a computer is a non-trivial task, particularly for people from non-technical backgrounds. Overcoming the steep learning curve associated with learning traditional programming languages, such as Prolog or Lisp, is a difficult problem currently facing psychology education. """"Hank"""" is a visual programming language that has been proposed as a solution to the programming overhead associated with teaching cognitive modelling. This paper discusses a programming walkthrough evaluation of the supporting material and modelling exercises used by The Open University for teaching cognitive modelling with Hank. This work is part of an ongoing evaluation project of Hank involving further theoretical and empirical studies. The key issues raised in this paper are: the consistent use of appropriate terminology, and the sufficiency, level and pace of the explanations provided

A Visual programming approach for teaching cognitive modelling

This paper describes an investigation into the use of a visual programming language to teach computer-based modelling to undergraduate cognitive psychology students. Four sets of evaluation studies were carried out. The findings of these theoretical and empirical evaluations are related to the design principles that informed the language and the context in which it was examined. The educational benefits of gaining some practical experience of cognitive modelling where highlighted in these studies, as was the importance of introducing the visual language within a sound teaching framework. The comments of the students and tutors regarding the use of the Hank visual programming language to teach cognitive modelling indicate that Hank avoids some of the syntactic problems associated with textual programming languages, it can be used to illustrate the flow of control during a program's execution, and it is intuitive and easy to use

The role of the graphic calculator in mediating graphing activity

The PIGMI (Portable Information Technologies for supporting Graphical Mathematics Investigations) Project investigated the role of portable technologies in facilitating development of students' graphing skills and concepts. This paper examines the impact of a recent shift towards calculating and computing tools as increasingly accessible, everyday technologies on the nature of learning in a traditionally difficult curriculum area. The paper focuses on the use of graphic calculators by undergraduates taking an innovative new mathematics course at the Open University. A questionnaire survey of both students and tutors was employed to investigate perceptions of the graphic calculator and the features which facilitate graphing and linking between representations. Key features included visualization of functions, immediate feedback and rapid graph plotting. A follow-up observational case study of a pair of students illustrated how the calculator can shape mathematical activity, serving a catalytic, facilitating and checking role. The features of technology-based activities which can structure and support collaborative problem solving were also examined. In sum, the graphic calculator technology acted as a critical mediator in both the students' collaboration and in their problem solving. The pedagogic implications of using portables are considered, including the tension between using and over-using portables to support mathematical activity