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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.

We describe the metaprogramming framework currently used in Lean, an interactive theorem prover based on dependent type theory. This framework extends Lean's object language with an API to some of Lean's internal structures and procedures, and provides ways of reflecting object-level expressions into the metalanguage. We provide evidence to show that our implementation is performant, and that it provides a convenient and flexible way of writing not only small-scale interactive tactics, but also more substantial kinds of automation.bridge the gap between interactive use and automation. Lean implements a version of the Calculus of Inductive Constructions [Coquand and Huet 1988;Coquand and Paulin 1990], the details of which are described in Section 3. Its elaborator and unification algorithms are designed around the use of type classes, which support algebraic reasoning, programming abstractions, and other generally useful means of expression. Lean also has parallel compilation and checking of proofs, and provides a server mode that supports a continuous compilation and rich user interaction in editing environments such as Emacs and Visual Studio Code. It currently has a conditional term rewriter and several components commonly found in state-of-the-art Satisfiability Modulo Theories (SMT) solvers, such as forward chaining, congruence closure [Nelson and Oppen 1980], handling of associative and commutative operators, and E-matching [Detlefs et al. 2005].In Lean, definitions are compiled to bytecode that can then be evaluated in an efficient virtual machine. This is one sense in which Lean can be viewed as a programming language. (Native compilation is under development.) We obtain a metaprogramming language by exposing an API for procedures implemented natively in Lean's underlying C++ code base, thus taking us outside the axiomatic framework. Within a Lean source file, the keyword meta marks a clear distinction between definitions that make use of such extensions and those that are in the pure object language. Metadefinitions can also call themselves recursively, relaxing the termination restriction imposed by ordinary type theory. Otherwise, definitions and metadefinitions look very much the same, and can be written side-by-side in a Lean source file.There are a number of advantages to this approach. One is that users do not have to learn a new programming language to write metaprograms; they can work with the same constructs and notation used to define ordinary objects in the theorem prover's library. Another advantage is that everything in that library is available for metaprogramming purposes, including integers, lists, datatype constructors, records, and algebraic structures. Finally, metaprograms can be written and debugged in the same interactive environment, making it possible to develop the object library and supporting automation at the same time.A key application for metaprogramming is to implement tactics, which is to say, procedures which facilitate interactive theorem proving by carrying out straightf...

Purpose – This paper aims to investigate the effects of different response options to a negative consumer review. When consumers buy online, they are often confronted with consumer reviews. A negative consumer review on an online shopping website may keep consumers from buying the product. Therefore, negative online consumer reviews are a serious problem for brands. Design/methodology/approach – In an online experiment of 446 participants, different response options towards a negative consumer review on an online shopping website were examined. The experimental data were analysed with linear regression models using product purchase intentions as the outcome variable. Findings – The results indicate that a positive customer review counteracts a negative consumer review more effectively than a positive brand response, whereas brand strength moderates this relationship. Including a reference to an independent, trusted source in a brand or a customer response is only a limited strategy for increasing the effectiveness of a response. Research limitations/implications – Additional research on other product categories and with subjects other than students is suggested to validate the findings. In future research, multiple degrees of the phrasing’s strength of the reference could be used. Practical implications – Assuming high quality products, brands should encourage their customers to write reviews. Strong brands can also reassure consumers by responding, whereas weak brands cannot. Originality/value – This research contributes to the online consumer reviews literature with new insights about the role of brand strength and referencing to an independent, trusted source.