Haptic palpation for medical simulation in virtual environments

Palpation is a physical examination technique where objects, e.g., organs or body parts, are touched with fingers to determine their size, shape, consistency and location. Many medical procedures utilize palpation as a supplementary interaction technique and it can be therefore considered as an essential basic method. However, palpation is mostly neglected in medical training simulators, with the exception of very specialized simulators that solely focus on palpation, e.g., for manual cancer detection. In this article we propose a novel approach to enable haptic palpation interaction for virtual reality-based medical simulators. The main contribution is an extensive user study conducted with a large group of medical experts. To provide a plausible simulation framework for this user study, we contribute a novel and detailed interaction algorithm for palpation with tissue dragging, which utilizes a multi-object force algorithm to support multiple layers of anatomy and a pulse force algorithm for simulation of an arterial pulse. Furthermore, we propose a modification for an off–the–shelf haptic device by adding a lightweight palpation pad to support a more realistic finger grip configuration for palpation tasks. The user study itself has been conducted on a medical training simulator prototype with a specific procedure from regional anesthesia, which strongly depends on palpation. The prototype utilizes a co-rotational finite-element approach for soft tissue simulation and provides bimanual interaction by combining the aforementioned techniques with needle insertion for the other hand. The results of the user study suggest reasonable face validity of the simulator prototype and in particular validate medical plausibility of the proposed palpation interaction algorithm.     

A BDI agent programming language with failure handling,declarative goals,and planning

Agents are an important technology that have the potential to take over contemporary methods for analysing, designing, and implementing complex software. The Belief-Desire-Intention (BDI) agent paradigm has proven to be one of the major approaches to intelligent agent systems, both in academia and in industry. Typical BDI agent-oriented programming languages rely on user-provided “plan libraries” to achieve goals, and online context sensitive subgoal selection and expansion. These allow for the development of systems that are extremely flexible and responsive to the environment, and as a result, well suited for complex applications with (soft) real-time reasoning and control requirements. Nonetheless, complex decision making that goes beyond, but is compatible with, run-time context-dependent plan selection is one of the most natural and important next steps within this technology. In this paper we develop a typical BDI-style agent-oriented programming language that enhances usual BDI programming style with three distinguished features: declarative goals, look-ahead planning, and failure handling. First, an account that mixes both procedural and declarative aspects of goals is necessary in order to reason about important properties of goals and to decouple plans from what these plans are meant to achieve. Second, lookahead deliberation about the effects of one choice of expansion over another is clearly desirable or even mandatory in many circumstances so as to guarantee goal achievability and to avoid undesired situations. Finally, a failure handling mechanism, suitably integrated with both declarative goals and planning, is required in order to model an adequate level of commitment to goals, as well as to be consistent with most real BDI implemented systems.     

Exploring inconsistencies between modal transition systems

It is commonplace to have multiple behaviour models that describe the same system but have been produced by different stakeholders or synthesized from different sources. Although in practice, such models frequently exhibit inconsistencies, there is a lack of tool support for analyzing them. There are two key difficulties in explaining why two behavioural models are inconsistent: (1) explanations often require branching structures rather than linear traces, or scenarios; and (2) there can be multiple sources of inconsistency and many different ways of explaining each one. In this paper, we present an approach that supports exploration of inconsistencies between modal transition systems, an extension to labelled transition systems. We show how to produce sound graphical explanations for inconsistencies, how to compactly represent all possible explanations in a composition of the models being compared, and how modelers can use this composition to explore the explanations encoded therein.     

A trajectory-based strict semantics for program slicing

We define a program semantics that is preserved by dependence-based slicing algorithms. It is a natural extension, to non-terminating programs, of the semantics introduced by Weiser (which only considered terminating ones) and, as such, is an accurate characterisation of the semantic relationship between a program and the slice produced by these algorithms.Unlike other approaches, apart from Weiser’s original one, it is based on strict standard semantics which models the ‘normal’ execution of programs on a von Neumann machine and, thus, has the advantage of being intuitive. This is essential since one of the main applications of slicing is program comprehension. Although our semantics handles non-termination, it is defined wholly in terms of finite trajectories, without having to resort to complex, counter-intuitive, non-standard models of computation. As well as being simpler, unlike other approaches to this problem, our semantics is substitutive. Substitutivity is an important property because it greatly enhances the ability to reason about correctness of meaning-preserving program transformations such as slicing.     

Standardized TTCN-3 specifications for SIP-ISUP/ISDN interworking testing

ETSI technical committee TISPAN currently funds the development of TTCN-3 network integration test suites using TTCN-3. Specialist task forces (STF) have already been initiated to implement and validate abstract test suites focusing on, e.g., SIP/ISUP and SIP/ISDN interworking units. In this paper, we report on our implementation approach and experiences made in the STF on testing interworking between SIP and ISDN/ISUP. Special attention has been given to the reuse of know-how and of existing TTCN-3 code available due to the existing SIP conformance test suite and the TTCN-3 test framework developed by ETSI for IPv6. Validation has been done using the test laboratory of a telecom network provider.     

Fault analysis of a PM brushless DC Motor using finite element method

Three-phase trapezoidal back-EMF permanent magnet (PM) machines are used in many applications where the reliability and fault tolerance are important requirements. Knowledge of the machine transient processes under various fault conditions is the key issue in evaluating the impact of machine fault on the entire electromechanical system. The machine electrical and mechanical quantities whose transient behaviors are of importance under fault conditions include the voltages and currents of the coils and phases, the electromagnetic torque, and the rotor speed. Experimental test based on true machines for such a purpose is impractical for its high cost and difficulty to make. Computer simulation based on the finite element method has shown its effectiveness in fault study in this paper. Before the finite element model was used to perform simulations under fault conditions, it was validated by test data under normal conditions. Three types of fault conditions-single-phase open circuit fault, phase-to-phase terminal short-circuit, and internal turn-to-turn short-circuit have been studied.     

Primary versus secondary insomnia in older adults: Subjective sleep and daytime functioning.

Most psychological research on insomnia has centered on primary insomnia (PI). Secondary insomnia (SI), though more common than PI, has received little attention because of its presumed unresponsiveness to treatment. The present study recruited older adults with PI, SI, and a comparison group of older adults with no insomnia (NI). Self-report assessments of sleep revealed no significant difference between the 2 insomnia groups. Daytime functioning measures found significant differences in impairment between the 3 groups with SI having the worst daytime functioning, followed by PI, which was worse than NI. Further analyses found substantial independence between sleep and daytime functioning. Implications of these findings for the clinical management of SI are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)