DrScheme is a programming environment for Scheme. It fully integrates a graphicsenriched editor, a parser for multiple variants of Scheme, a functional read-eval-print loop, and an algebraic printer. The environment is especially useful for students, because it has a tower of syntactically restricted variants of Scheme that are designed to catch typical student mistakes and explain them in terms the students understand. The environment is also useful for professional programmers, due to its sophisticated programming tools, such as the static debugger, and its advanced language features, such as units and mixins.Beyond the ordinary programming environment tools, DrScheme provides an algebraic stepper, a context-sensitive syntax checker, and a static debugger. The stepper reduces Scheme programs to values, according to the reduction semantics of Scheme. It is useful for explaining the semantics of linguistic facilities and for studying the behavior of small programs. The syntax checker annotates programs with font and color changes based on the syntactic structure of the program. On demand, it draws arrows that point from bound to binding occurrences of identifiers. It also supports α-renaming. Finally, the static debugger provides a type inference system that explains specific inferences in terms of a value-flow graph, selectively overlaid on the program text.

Abstract. Programmers rely on the correctness of the tools in their programming environments. In the past, semanticists have studied the correctness of compilers and compiler analyses, which are the most important tools. In this paper, we make the case that other tools, such as debuggers and steppers, deserve semantic models, too, and that using these models can help in developing these tools.Our concrete starting point is the algebraic stepper in DrScheme, our Scheme programming environment. The algebraic stepper explains a Scheme computation in terms of an algebraic rewriting of the program text. A program is rewritten until it is in a canonical form (if it has one). The canonical form is the final result.The stepper operates within the existing evaluator, by placing breakpoints and by reconstructing source expressions from source information placed on the stack. This approach raises two questions. First, do the run-time breakpoints correspond to the steps of the reduction semantics? Second, does the debugging mechanism insert enough information to reconstruct source expressions?To answer these questions, we develop a high-level semantic model of the extended compiler and run-time machinery. Rather than modeling the evaluation as a low-level machine, we model the relevant low-level features of the stepper's implementation in a high-level reduction semantics. We expect the approach to apply to other semantics-based tools. The Correctness of Programming Environment ToolsProgramming environments provide many tools that process programs semantically. The most common ones are compilers, program analysis tools, debuggers, and profilers. Our DrScheme programming environment [9,8] also provides an algebraic stepper for Scheme. It explains a program's execution as a sequence of reduction steps based on the ordinary laws of algebra for the functional core [2,

ABSTRACT. This study investigated emotional awareness, the recognition and understanding of different emotional states, among a non‐clinical population of adolescents and young adults with mental handicaps. While emotional awareness showed a high positive correlation with language comprehension, the results suggest that many of these individuals have specific emotional awareness deficits which are not in line with their language comprehension abilities. This finding suggests that the assessment of emotional awareness would be an important step in the choice of a self‐report measure to assess an individual's emotional state.

Data are reported from an exploratory study looking at the prevalence of sleep problems (broken sleep and limited hours of sleep) in a population of handicapped children. Some degree of difficulty occurred in over a third of the population. There were strong associations with age, a range of serious daytime behavioural difficulties and indices of family stress. Some support for distinct subgroups (night waking, limited hours) was obtained. The implications of these findings are discussed.

Bidomain theory for cardiac tissue assumes two interpenetrating anisotropic media--intracellular (i) and extracellular (e)--connected everywhere via a cell membrane; four local parameters sigma(i,e)(l,t) specify conductivities in the longitudinal (l) and transverse (t) directions with respect to cardiac muscle fibers. The full bidomain model for the propagation of electrical activation consists of coupled elliptic-parabolic partial differential equations for the transmembrane potential upsilon(m) and extracellular potential phi(e), together with quasistatic equations for the flow of current in the extracardiac regions. In this work we develop a preliminary assessment of the consequences of neglecting the effect of the passive extracardiac tissue and intracardiac blood masses on wave propagation in isolated whole heart models and describe a decoupling procedure, which requires no assumptions on the anisotropic conductivities and which yields a single reaction-diffusion equation for simulating the propagation of activation. This reduction to a decoupled model is justified in terms of the dimensionless parameter epsilon = (sigma(i)(l)sigma(e)(t) - sigma(i)(t)sigma(e)(l))/(sigma(i)(l) + sigma(e)(l))(sigma(i)(t) + sigma(e)(t)). Numerical simulations are generated which compare propagation in a sheet H of cardiac tissue using the full bidomain model, an isolated bidomain model, and the decoupled model. Preliminary results suggest that the decoupled model may be adequate for studying general properties of cardiac dynamics in isolated whole heart models.