Core Hybrid Event-B I: Single Hybrid Event-B machines

Faced with the increasing need for correctly designed hybrid and cyber-physical systems today, the problem of including provision for continuously varying behaviour as well as the usual discrete changes of state is considered in the context of Event-B. An extension of Event-B called Hybrid Event-B is presented, that accommodates continuous behaviours (called pliant events) in between familiar discrete transitions (called mode events in this context). The continuous state change can be specified by a combination of indirect specification via ordinary differential equations, or direct specification via assignment of variables to values that depend on time, or indirect specification by demanding that behaviour obeys a time dependent predicate. The syntactic elements of the extension are discussed, and the semantics is described in terms of the properties of time dependent valuations of variables. Refinement is examined in detail, with reference to the notion of refinement inherited from discrete Event-B. A full suite of proof obligations is presented, covering all aspects of the new framework. A selection of examples and case studies is presented. A particular challenge - bearing in mind the desirability of conforming to existing intuitions about discrete Event-B, and the impact on tool support (as embodied in tools for discrete Event-B like Rodin) - is to design the whole framework so as to disturb as little as possible the existing structures for handling discrete Event-B

Towards an evidence‐base for student wellbeing and mental health : definitions, developmental transitions and data sets

Against a background of huge changes in the world of university and college students since the turn of the millennium, together with a multitude of reports on student mental health/wellbeing, this article argues that the field of student mental health is hampered by the imprecise use of terms, a rush to action by universities in the absence of a robust evidence‐base, and a lack of overall coordination and collaboration in the collection and use of data. In response, we argue for clearer and more consistent use of definitions of, as well as differentiations between, student wellbeing and mental health, for a longitudinal approach to the student body that captures their developmental transitions to and through university, and a strategic and systematic approach to the use of bona fide measures in the collection of data on wellbeing and on the process of outcomes in embedded university counselling services. Such a coordinated approach will provide the necessary evidence‐base upon which to develop and deliver appropriate support and interventions to underpin and enhance the quality of students’ lives and learning while at university or college

Is the ADA/EASD algorithm for the management of type 2 diabetes (January 2009) based on evidence or opinion? A critical analysis

The ADA and the EASD recently published a consensus statement for the medical management of hyperglycaemia in patients with type 2 diabetes. The authors advocate initial treatment with metformin monotherapy and lifestyle modification, followed by addition of basal insulin or a sulfonylurea if glycaemic goals are not met (tier 1 recommendations). All other glucose-lowering therapies are relegated to a secondary (tier 2) status and only recommended for selected clinical settings. In our view, this algorithm does not offer physicians and patients the appropriate selection of options to individualise and optimise care with a view to sustained control of blood glucose and reduction both of diabetes complications and cardiovascular risk. This paper critically assesses the basis of the ADA/EASD algorithm and the resulting tiers of treatment options