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Software and systems modeling 20(3), 611-639 (2021). doi:10.1007/s10270-021-00876-z, Published by Springer, Berlin; Heidelberg; New York, NY

Environmental sustainability is an increasingly important subject for public transportation organizations. For passenger train operators, modernization projects provide key opportunities to improve the environmental impact of their rolling stock by making informed design decisions at the midpoint of the life cycle of their trains. Life Cycle Assessment (LCA) is widely adopted as the main instrument for evaluating environmental impact. However, in the past LCA was rarely used in the earlier design stages, where it is most effective, due to constrained access to data, information, and LCA-specific expertise. To this end, a purpose-built streamlined LCA tool for train modernization is developed and demonstrated, following a Design Science Research approach. The developed tool simplifies the application of LCA employing four main design principles: (1) sacrificing the declarative function of LCA, (2) the use of Input&ndash, Output-based Life Cycle Inventory, (3) the inclusion of &lsquo, shadow costs&rsquo, (4) the limitation of the included environmental impact categories. By streamlining the application of LCA in this way, it becomes possible to introduce LCA-based principles and ways of thinking into a process that would otherwise be inaccessible to performing LCA in: the early design stages of modernization projects.

There has been substantial controversy regarding treatment of congenital heart defects in infants with trisomies 13 and 18. Most reports have focused on surgical outcomes versus expectant treatment, and rarely there has been an effort to consolidate existing evidence into a more coherent way to help clinicians with decision-making and counseling families. An extensive review of the existing literature on cardiac surgery in patients with these trisomies was conducted from 2004 to 2020. The effects of preoperative and perioperative factors on in-hospital and long-term mortality were analyzed, as well as possible predictors for postoperative chronic care needs such as tracheostomy and gastrostomy. Patients with minimal or no preoperative pulmonary hypertension and mechanical ventilation undergoing corrective surgery at a weight greater than 2.5 kg suffer from lower postoperative mortality. Infants with lower-complexity cardiac defects are likely to benefit the most from surgery, although their expected mortality is higher than that of infants without trisomy. Omphalocele confers an increased mortality risk regardless of cardiac surgery. Gastrointestinal comorbidities increased the risk of gastrostomy tube placement, while those with prolonged mechanical ventilation and respiratory comorbidities are more likely to require tracheostomy. Cardiac surgery is feasible in children with trisomies 13 and 18 and can provide improved long-term results. However, this is a clinically complex population, and both physicians and caretakers should be aware of the long-term challenges these patients face following surgery when discussing treatment options.

In our rapidly changing, interconnected world, education that helps children develop into collaborative problem solvers who are ready for the workforce is essential.

Although Model-Based Software Engineering (MBE) is a widely accepted Software Engineering (SE) discipline, no agreed-upon core set of concepts and practices (i.e., a Body of Knowledge) has been defined for it yet. With the goals of characterizing the contents of the MBE discipline, promoting a global consistent view of it, clarifying its scope with regard to other SE disciplines, and defining a foundation for the development of educational curricula on MBE, this paper proposes the contents for a Body of Knowledge for MBE. We also describe the methodology that we have used to come up with the proposed list of contents, as well as the results of a survey study that we conducted to sound out the opinion of the community on the importance of the proposed topics and their level of coverage in the existing SE curricula.

Recent visualization research efforts have incorporated experimental techniques and perceptual models from the vision science community. Perceptual laws such as Weber's law, for example, have been used to model the perception of correlation in scatterplots. While this thread of research has progressively refined the modeling of the perception of correlation in scatterplots, it remains unclear as to why such perception can be modeled using relatively simple functions, e.g., linear and log-linear. In this paper, we investigate a longstanding hypothesis that people use visual features in a chart as a proxy for statistical measures like correlation. For a given scatterplot, we extract 49 candidate visual features and evaluate which best align with existing models and participant judgments. The results support the hypothesis that people attend to a small number of visual features when discriminating correlation in scatterplots. We discuss how this result may account for prior conflicting findings, and how visual features provide a baseline for future model-based approaches in visualization evaluation and design.

EULYNX is an EU-level collaboration between railway infrastructure managers to standardize signaling interfaces. The main goal of EULYNX is to provide, on an EU scale, a modular and flexible railroad architecture where components can easily be exchanged. This also opens the market for specialized manufacturers that do not supply the full range of control assets, but only single components. Related to EULYNX is FormaSig, an effort to establish the safety of the EULYNX standard with mathematical rigor. In particular, one of the main objectives of FormaSig is to translate the entire EULYNX standard from the semi-formal language SysML to the formal language mCRL2. The resulting mCRL2 models will subsequently be checked for important safety requirements and used for automated testing of actual EULYNX systems. This paper presents a first case study in this direction, focusing on the EULYNX Point interface, which we have converted to an mCRL2 model. We have also derived nine safety requirements, which have all been automatically compared with the mCRL2 model. Finally, we have used the mCRL2 model to test an industrial simulator of the EULYNX Point interface fully automatically.

Purpose Oncological patients are susceptible to various severe viral infections, including influenza. Vaccinating oncological patients and their household contacts (“cocoon vaccination”) may protect these patients from contracting influenza. To understand the potential of cocoon vaccination in oncological patients, this study assesses the influenza vaccination status of oncological patients and their household contacts and their considerations regarding the vaccination. Methods In this retrospective study, oncological patients with a solid tumor were asked to fill in a questionnaire about their own and their household contacts’ influenza vaccination status in the influenza season of 2018–2019. Results Ninety-eight patients were included (response rate 88%). The influenza vaccination rates of oncological patients and their first household contacts were 43.9% and 44.9%, respectively. The majority of vaccinated patients and vaccinated first household contacts had been advised by their general practitioner to get the vaccination. A minority of the first household contacts reported getting vaccinated specifically because of the patient’s vulnerability. Unvaccinated patients and unvaccinated household contacts mainly believed the vaccination was unnecessary or were afraid of side effects. None of the included patients had been hospitalized with influenza. Conclusion The oncological patients’ and first household contacts’ vaccination rates in this study were lower than the vaccination rates of the general Dutch population of over 60 years old, possibly due to a lack of knowledge and misconceptions about the vaccination. Further research is required to establish whether cocoon vaccination can contribute to protecting oncological patients from contracting an influenza infection.

This study investigated the contribution of practice in learning from Demonstration-Based Training (DBT) videos for software training. An experiment with three conditions is reported: practice followed by video (practice-video), video followed by practice (videopractice), and video only. The combination of practice and video was expected to enhance learning more than the video only condition. Also, practice-after was expected to be more effective than practice-before. The 82 participants, elementary students (mean age 11.2), achieved significant learning gains, reaching moderate to high levels of success on the immediate and delayed post-tests, and the transfer test. No practice effect was found. Also, there was no difference in test performance between practice conditions. The discussion advances several options for enhancing the effectiveness of the DBT-videos.

We propose a model-driven engineering approach that facilitates the production of tool chains that use the popular model checker Uppaal as a back-end analysis tool. In this approach, we introduce a metamodel for Uppaal ’s input model, containing both timed-automata concepts and syntax-related elements for C-like expressions. We also introduce a metamodel for Uppaal ’s query language to specify temporal properties; as well as a metamodel for traces to interpret Uppaal ’s counterexamples and witnesses. The approach provides a systematic way to build software bridging tools (i.e., tools that translate from a domain-specific language to Uppaal ’s input language) such that these tools become easier to debug, extend, reuse and maintain. We demonstrate our approach on five different domains: cyber-physical systems, hardware-software co-design, cyber-security, reliability engineering and software timing analysis.

Model-based verification allows to express behavioral correctness conditions like the validity of execution states, boundaries of variables or timing at a high level of abstraction and affirm that they are satisfied by a software system. However, this requires expressive models which are difficult and cumbersome to create and maintain by hand. This paper presents a framework that automatically derives behavioral models from real-sized Java programs. Our framework builds on the EMF/ECore technology and provides a tool that creates an initial model from Java bytecode, as well as a series of transformations that simplify the model and eventually output a timed-automata model that can be processed by a model checker such as UPPAAL. The framework has the following properties: (1) consistency of models with software, (2) extensibility of the model derivation process, (3) scalability and (4) expressiveness of models. We report several case studies to validate how our framework satisfies these properties., Comment: In Proceedings MARS 2017, arXiv:1703.05812

Purpose Intraoperative extracorporeal membrane oxygenation (ECMO) as the primary means of tissue oxygenation during pediatric lung transplantation has been increasingly used as an alternative to cardiopulmonary bypass (CPB). Current literature in adults undergoing lung transplantation suggest a benefit of ECMO over CPB. However, there is limited data on the outcomes in children. We sought to determine outcomes of intraoperative ECMO versus CPB during pediatric lung transplantation at our institution. Methods We retrospectively reviewed the records of pediatric patients ( Results Of the 35 children who underwent lung transplantation over this period, 14 (40.0%) were transplanted on ECMO support while 21 (60.0%) were transplanted on CPB. There was no statistically significant difference in mortality at 30 days (0.0% ECMO vs 4.8 % CPB), 6 months (0.0% ECMO vs 11.1% CPB), or at 1 year post-transplant (14.3% ECMO vs 33.3% CPB). Other analyzed variables did not differ significantly (Table 1). Conclusion Although the use of ECMO as a primary means of tissue oxygenation in adult lung transplantation has shown a benefit when compared to CPB, this study shows no difference in outcomes within intraoperative and postoperative variables during pediatric lung transplantation. This data is representative of transplants within a single high-volume institution; data from additional institutions may strengthen these observations.

Background In the Netherlands, each year a three-day international multidisciplinary trauma masterclass is organized to provide the knowledge and skills needed to care for critically injured trauma patients. This study was designed to longitudinally evaluate the effect of the course on participant’s self-assessment of their own ability and confidence to perform general and specific skills. Methods Between 2013 and 2016, all participants were invited to complete a questionnaire before and during follow-up. Participants were asked to self-assess their level of confidence to perform general skills (communication, teamwork, leadership) and specific skills. Mean scores were calculated, and mixed models were used to evaluate correlation. Results We asked 265 participants to participate. Response rate was 64% for the pre-questionnaire, 63% for the post-questionnaire and for 3 months, 1 year and 2 years, respectively, 40%, 30%, 20%. The surgical group showed a statistically significant increase in self-assessed confidence for general skills (3.82–4.20) and specific technical skills (3.01–3.83; p p Conclusions This study demonstrated a sustained positive effect of a dedicated multidisciplinary trauma training curriculum on participant’s self-assessed confidence to perform both general and specific technical skills necessary for the care of injured patients. Given the known association between confidence and competence, these findings provide evidence that dedicated trauma training curricula can provide positive lasting results. Level of evidence This is a basic science paper and therefore does not require a level of evidence.

The 13th annual Community Bankers Symposium, cosponsored by the Federal Reserve Bank of Chicago, the Federal Deposit Insurance Corporation (FDIC), and the Office of the Comptroller of the Currency (OCC), was held at the Federal Reserve Bank of Chicago on November 16, 2018. During a full day of speeches and panels, a group of 160 community bank executives, financial industry practitioners, and regulatory agency professionals who work in the Seventh Federal Reserve District1 explored the evolving landscape of community banking.2 This article provides an overview of the event?s key presentations and discussions.

International audience; Model-based Software Engineering (MBSE) is now accepted as a Software Engineering (SE) discipline and is being taught as part of more general SE curricula. However, an agreed core of concepts, mechanisms and practices-which constitutes the Body of Knowledge of a discipline-has not been captured anywhere, and is only partially covered by the SE Body of Knowledge (SWEBOK). With the goals of characterizing the contents of the MBSE discipline, promoting a consistent view of it worldwide, clarifying its scope with regard to other SE disciplines, and defining a foundation for a curriculum development on MBSE, this paper provides a proposal for an extension of the contents of SWEBOK with the set of fundamental concepts, terms and mechanisms that should constitute the MBSE Body of Knowledge. CCS CONCEPTS • Social and professional topics → Software engineering education ; Model curricula; KEYWORDS Model-Based Software Engineering, Body of Knowledge.

We introduce a formal specification language locks, that allow security practitioners to express as well as compose security goals in a convenient manner. locks supports the specification of the most common security properties over generic attributes, both for qualitative and quantitative goals. To make our language independent of a specific security framework, we evaluate locks over a generic attack model, namely the structural attack model (sam), which over-arches the most prominent graphical threat models. Furthermore, we equip our language with a concise grammar, type rules and denotational semantics, thus laying the foundations of an automated tool. We take a number of informal security goals from the literature and show how they can be formally expressed in our language.

With the aim of providing knowledge for informed choices, a series of tools have been developed for archaeological heritage management in the Netherlands. They include maps, datasets, methods, guidelines, best practice and web-based applications to facilitate the effective and efficient selection of valuable archaeological remains. The products relate to archaeological predictive modelling, disturbances by agriculture and other activities, archaeological heritage maps, prospection methods, research questions and scientific syntheses to close the archaeological heritage management cycle.

Model transformation is one of the key tasks in model-driven engineering and relies on the efficient matching and modification of graph-based data structures; its sibling graph rewriting has been used to successfully model problems in a variety of domains. Over the last years, a wide range of graph and model transformation tools have been developed – all of them with their own particular strengths and typical application domains. In this paper, we give a survey and a comparison of the model and graph transformation tools that participated at the Transformation Tool Contest 2011. The reader gains an overview of the field and its tools, based on the illustrative solutions submitted to a Hello World task, and a comparison alongside a detailed taxonomy. The article is of interest to researchers in the field of model and graph transformation, as well as to software engineers with a transformation task at hand who have to choose a tool fitting to their needs. All solutions referenced in this article provide a SHARE demo. It supported the peer-review process for the contest, and now allows the reader to test the tools online.

Fault trees are a key technique in safety and reliability engineering. Their application includes aerospace, nuclear power, car, and process engineering industries. Various fault tree extensions exist that increase expressiveness while yielding succinct models. Their analysis is a main bottleneck: techniques do not scale and require manual effort. Formal methods have an enormous potential to solve these issues. We discuss a mixture of formal method techniques resulting in a fully automated and scalable approach to analyze Dugan’s dynamic fault trees.

Hardware-software (HW-SW) co-design allows to meet system-level objectives by exploiting the synergy of hardware and software. Current tools and approaches for HW-SW co-design face difficulties coping with the increasing complexity of modern-day application due to, e.g., concurrency and energy constraints. Therefore, an automated modeling approach is needed which satisfies modularity, extensibility and interoperability requirements. Model-Driven Engineering (MDE) is a prominent paradigm that, by treating models as first-class citizens, helps to fulfill these requirements. This paper presents a state-of-the-art MDE-based framework for HW-SW co-design of dataflow applications, based on synchronous dataflow (SDF) graph formalism. In the framework, we introduce a reusable set of three coherent metamodels for creating HW-SW co-design models concerning SDF graphs, hardware platforms and allocation of SDF tasks to hardware. The framework also contains model transformations that cast these models into priced timed-automata models, the input language of the well-known model checker Uppaal Cora. We demonstrate how our framework satisfies the requirements of modularity, extensibility and interoperability in an industrial case study.

Title. Task-oriented training in rehabilitation after stroke: systematic review. Aim. This paper is a report of a review conducted to provide an overview of the evidence in the literature on task-oriented training of stroke survivors and its relevance in daily nursing practice. Background. Stroke is the second leading cause of death and one of the leading causes of adult disability in the Western world. The use of neurodevelopmental treatment in the daily nursing care of stroke survivors does not improve clinical outcomes. Nurses are therefore exploring other forms of rehabilitation intervention, including task-oriented rehabilitation. Despite the growing number of studies showing evidence on task-oriented interventions, recommendations for daily nursing practice are lacking. Data Sources. A range of databases was searched to identify papers addressing taskoriented training in stroke rehabilitation, including Medline, CINAHL, Embase and the Cochrane Library of systematic reviews. Papers published in English between January 1996 and September 2007 were included. There were 42 papers in the final dataset, including nine systematic reviews. Review methods. The selected randomized controlled trials and systematic reviews were assessed for quality. Important characteristics and outcomes were extracted and summarized. Results. Studies of task-related training showed benefits for functional outcome compared with traditional therapies. Active use of task-oriented training with stroke survivors will lead to improvements in functional outcomes and overall healthrelated quality of life. Conclusion. Generally, task-oriented rehabilitation proved to be more effective. Many interventions are feasible for nurses and can be performed in a ward or at home. Nurses can and should play an important role in creating opportunities to practise meaningful functional tasks outside of regular therapy sessions.

Most reported MDA approaches give much attention to structural aspects in PSMs and in generated code, and less attention to the PIM level and the behaviour of the modelled applications. Consequently, application behaviour is generally not (well) defined at the PIM level. This paper presents an MDA-based approach that incorporates behaviour modelling at the PIM level in the development of a specific category of applications, i.e., context-aware mobile applications. The paper also illustrates a behaviour model transformation realized by using Medini QVT , which is a tool that implements the Query/ View/ Transformation (QVT) Relations specification defined by OMG for model-to-model transformations.

It has been claimed by many in the graph transformation community that model transformation, as understood in the context of Model Driven Architecture, can be seen as an application of graph transformation. In this paper we substantiate this claim by giving a graph transformation-based semantics to one of the original QVT language proposals; that is, we define a mechanism that will translate any model transformation definition in the QVT language to a graph production system whose effect is to apply that model transformation. The translation has been fully implemented.

In this short paper we describe the setup and results of a new initiative to compare graph transformation tools, carried out as part of the AGTIVE 2007 symposium on "Applications of Graph Transformation with Industrial Relevance". The initiative took the form of a contest, consisting of two rounds: the first round was a call for cases, the second round a call for solutions. The response to both rounds was very good, leading to the conclusion that this is an initiative worth repeating. There are, however, a number of lessons to be learned; these are summarised here, in order to improve the organisation and the eventual benefits of this type of contest.

We know by now that evolution in software is inevitable. Given that is so, we should not just allow for but accommodate for change throughout the software lifecycle. The claim of this paper is that, in order to accommodate for change effectively, we need a modelling discipline with a built-in notion of refinement, so that domain concepts can be defined and understood on their appropriate level of abstraction, and change can be captured on that same level. Refinement serves to connect levels of abstraction within the same model, enabling a simultaneous understanding of that same model on different levels. We propose the term model pattern for the central concept in such a modelling discipline.

The development of medical informatics—the application of computing power to medicine—has greatly improved the science and practice of oncology and cancer care, allowing us to make more informed decisions. Despite the development of these new technologies, however, informatics systems are still limited by the nature of the human beings who make sense of the information they process. In this chapter we focus on the problems and the opportunities that result from using human vision to explore datasets and communicate results. We begin with an introduction to the functional properties of the human visual system. This is followed by a discussion of how this knowledge can help us to develop effective ways of visualizing information, effectively “amplifying” the intelligence of the visual system to enable it to detect trends and outliers in a dataset. We then discuss two examples of how this approach can be applied to the design of improved informatics systems: the effective display of quantitative data, and the effective display of medical images.

Visual search can be resumed more rapidly following a brief interruption to an old display than it can be initiated on a new display, pointing to a critical role for memory in search (Lleras, Rensink, & Enns, 2005). Here, we examine how thisrapid resumption is affected by changes made to the display during the interruption of search. Rapid resumption was found to depend on the prior presentation of the target, not merely the distractor items (Experiment 1), and was unaffected by the relocation of all distractor items (Experiment 2). Further, whereas changes to response-irrelevant features of the target did not eliminate rapid resumption (Experiment 3), changes to response-relevant features did (Experiment 4). These results point to the target specificity of rapid resumption and are consistent with reentrant theories of visual awareness.

This paper addresses the question how to verify that the local workflow of an organisation participating in a cross-organisational collaboration is in compliance with the globally specified rules of that collaboration. We assume that the collaborative workflow is specified as a BPMN Collaboration Diagram and the local workflows as BPMN Process Diagrams. We then employ existing LTL semantics of the former and token semantics of the latter to verify conformance. We use the graph transformation tool GROOVE to automate the verification, and exemplify our approach with a case study from the financial markets domain.

Several kinds of statistical properties can be rapidly extracted from visual displays (e.g., luminance and roughness, Olive, A., & Torralba, A. (2001). Modeling the shape of the scene: a holistic representation of the spatial envelope. International Journal of Computational Vision, 42, 145–175). Here, we investigate whether this phenomenon extends to meaning contained in Arabic numerals. Observers were shown brief displays containing two sets of numerals and asked to determine which contained the largest average value. Comparisons were made more quickly and accurately between displays of digits than between displays of letters and shapes; this effect could not be attributed to task instructions. When numeric meaning could be used in a classification task, performance was better for digits than for letters, but when numeric meaning could not be used as a basis of classification, performance was approximately equal across stimulus types, suggesting that numeric meaning is rapidly extracted only when it is task-relevant. The digit advantage was eliminated with unlimited viewing time, suggesting that this process is used when counting is not possible. Dual-task methodology revealed that this process requires limited-capacity attentional resources.

An MDA-based design approach should be able to accommodate designs at different levels of platform-independence. We have previously proposed a design approach [2], which allows these levels to be identified. An important feature of this approach is the notion of abstract platform. An abstract platform is determined by considering the platform characteristics that are relevant for applications at a certain level of platform-independence as well as the various design goals. In this paper, we discuss how our design approach can be supported using the MDA standards UML 2.0 and MOF 2.0. Since our methodological framework is based on the notion of abstract platform, we pay particular attention to the representation of abstract platforms and the language requirements to specify abstract platforms.

Mobile health systems can extend the enterprise computing system of the healthcare provider by bringing services to the patient any time and anywhere. We propose a model-driven design and development methodology for the development of the m-health components in such extended enterprise computing systems. The methodology applies a model-driven design and development approach augmented with formal validation and verification to address quality and correctness and to support model transformation. Recent work on modelling applications from the healthcare domain is reported. One objective of this work is to explore and elaborate the proposed methodology. At the University of Twente we are developing m-health systems based on Body Area Networks (BANs). One specialization of the generic BAN is the health BAN, which incorporates a set of devices and associated software components to provide some set of health-related services. A patient will have a personalized instance of the health BAN customized to their current set of needs. A health professional interacts with their patients¿ BANs via a BAN Professional System. The set of deployed BANs are supported by a server. We refer to this distributed system as the BAN System. The BAN system extends the enterprise computing system of the healthcare provider. Development of such systems requires a sound software engineering approach and this is what we explore with the new methodology. The methodology is illustrated with reference to recent modelling activities targeted at real implementations. In the context of the Awareness project BAN implementations will be trialled in a number of clinical settings including epilepsy management and management of chronic pain.

It has often been assumed that when we use vision to become aware of an object or event in our surroundings, this must be accompanied by a corresponding visual experience (i.e., seeing). The studies reported here show that this assumption is incorrect. When observers view a sequence of displays alternating between an image of a scene and the same image changed in some way, they often feel (or sense) the change even though they have no visual experience of it. The subjective difference between sensing and seeing is mirrored in several behavioral differences, suggesting that these are two distinct modes of conscious visual perception.

In various chemical processes thorough homogeneous mixing is of great importance. Due to their small characteristic dimensions, micromixers have a great potential to achieve fast and uniform mixing. However, in the field of powder synthesis from precipitation processes the use of standard micromixers is severely limited because of rapid clogging of the microchannels. As an alternative, mixing nozzles which are less susceptible to fouling can provide a sufficient mixing quality. The flow field and fluid distribution inside multi-fluid droplets during droplet formation is simulated. Depending on the geometry and flow rates, complex velocity fields and flow distributions are found and the impact on the mixing efficiency is qualitatively deduced. Furthermore, we point out how the tendency of fouling can be further reduced with the help of improved nozzle geometries.

Item does not contain fulltext Cerebral amyloid angiopathy (CAA) is the result of the deposition of an amyloidogenic protein in cortical and leptomeningeal vessels. The most common type of CAA is caused by amyloid beta-protein (Abeta), which is particularly associated with Alzheimer's disease (AD). Excessive Abeta-CAA formation can be caused by several mutations in the Abeta precursor protein and presenilin genes. The origin of Abeta in CAA is likely to be neuronal, although cerebrovascular cells or the circulation cannot be excluded as a source. Despite the apparent similarity, the pathogenesis of CAA appears to differ from that of senile plaques in several aspects, including the mechanism of Abeta-induced cellular toxicity, the extent of inflammatory reaction and the role of oxidative stress. Therefore, therapeutic strategies for AD should, at least in part, also target CAA. Moreover, CAA and cerebrovascular disease (CVD) may set a lower threshold for AD-like changes to cause dementia and may even cause dementia on its own, since patients with AD and CAA and/or CVD appear to be more cognitively impaired than patients with only AD. In conclusion, the precise impact of CAA on AD or dementia remains unclear, however, its role may have been underestimated in the past, and more extensive studies of in vitro and in vivo models for CAA will be needed to elucidate the importance of CAA-specific approaches in designing intervention strategies for AD.

Johansson's point-light walker figures remain one of the most powerful and convincing examples of the role that motion can play in the perception of form (Johansson, 1973 Perception & Psychophysics14 201–211; 1975 Scientific American232(6) 76–88). In the current work, we use a dual-task paradigm to explore the role of attention in the processing of such stimuli. In two experiments we find striking differences in the degree to which direction-discrimination performance in point-light walker displays appears to rely on attention. Specifically, we find that performance in displays thought to involve top – down processing, either in time (experiment 1) or space (experiment 2) is adversely affected by dividing attention. In contrast, dividing attention has little effect on performance in displays that allow low-level, bottom – up computations to be carried out. We interpret these results using the active/passive motion distinction introduced by Cavanagh (1991 Spatial Vision5 303–309).

International audience; We describe a method for assessing the visualization literacy (VL) of a user. Assessing how well people understand visualizations has great value for research (e. g., to avoid confounds), for design (e. g., to best determine the capabilities of an audience), for teaching (e. g., to assess the level of new students), and for recruiting (e. g., to assess the level of interviewees). This paper proposes a method for assessing VL based on Item Response Theory. It describes the design and evaluation of two VL tests for line graphs, and presents the extension of the method to bar charts and scatterplots. Finally, it discusses the reimplementation of these tests for fast, effective, and scalable web-based use.

Magicians use misdirection to prevent you from realizing the methods used to create a magical effect, thereby allowing you to experience an apparently impossible event. Magicians have acquired much knowledge about misdirection, and have suggested several taxonomies of misdirection. These describe many of the fundamental principles in misdirection, focusing on how misdirection is achieved by magicians. In this article we review the strengths and weaknesses of past taxonomies, and argue that a more natural way of making sense of misdirection is to focus on the perceptual and cognitive mechanisms involved. Our psychologically-based taxonomy has three basic categories, corresponding to the types of psychological mechanisms affected: perception, memory, and reasoning. Each of these categories is then divided into subcategories based on the mechanisms that control these effects. This new taxonomy can help organize the magicians’ knowledge of misdirection in a meaningful way, and facilitate the dialogue between magicians and scientists.

Human vision briefly retains a trace of a stimulus after it disappears. This trace—iconic memory—is often believed to be a surrogate for the original stimulus, a representational structure that can be used as if the original stimulus were still present. To investigate its nature, a flicker-search paradigm was developed that relied upon a full scan (rather than partial report) of its contents. Results show that for visual search it can indeed act as a surrogate, with little cost for alternating between visible and iconic representations. However, the duration over which it can be used depends on the type of task: some tasks can use iconic memory for at least 240 ms, others for only about 190 ms, while others for no more than about 120 ms. The existence of these different limits suggests that iconic memory may have multiple layers, each corresponding to a particular level of the visual hierarchy. In this view, the inability to use a layer of iconic memory may reflect an inability to maintain feedback connections to the corresponding representation.

Class invariants are a highly useful feature for the verification of object-oriented programs, because they can be used to capture all valid object states. In a sequential program setting, the validity of class invariants is typically described in terms of a visible state semantics, i.e., invariants only have to hold whenever a method begins or ends execution, and they may be broken inside a method body. However, in a concurrent setting, this restriction is no longer usable, because due to thread interleavings, any program state is potentially a visible state. In this paper we present a new approach for reasoning about class invariants in multithreaded programs. We allow a thread to explicitly break an invariant at specific program locations, while ensuring that no other thread can observe the broken invariant. We develop our technique in a permission-based separation logic environment. However, we deviate from separation logic's standard rules and allow a class invariant to express properties over shared memory locations (the invariant footprint), independently of the permissions on these locations. In this way, a thread may break or reestablish an invariant without holding permissions to all locations in its footprint. To enable modular verification, we adopt the restrictions of Muller's ownership-based type system.

Observers inspected normal, high quality colour displays of everyday visual scenes while their eye movements were recorded. A large display change occurred each time an eye blink occurred. Display changes could either involve “Central Interest” or “Marginal Interest” locations, as determined from descriptions obtained from independent judges in a prior pilot experiment. Visual salience, as determined by luminance, colour, and position of the Central and Marginal Interest changes were equalized. The results obtained were very similar to those obtained in prior experiments showing failure to detect changes occurring simultaneously with saccades, flicker, or “mudsplashes” in the visual scene: Many changes were very hard to detect, and Marginal Interest changes were harder to detect than Central Interest changes. Analysis of eye movements showed, as expected, that the probability of detecting a change depended on the eye's distance from the change location. However a surprising finding was that both for Centr...

One of the more powerful impressions created by vision is that of a coherent, richly detailed world where everything is present simultaneously. Indeed, this impression is so compelling that we tend to ascribe these properties not only to the external world, but to our internal representations as well. But results from several recent experiments argue against this latter ascription. For example, changes in images of real-world scenes often go unnoticed when made during a saccade, flicker, blink, or movie cut. This “change blindness” provides strong evidence against the idea that our brains contain a picture-like representation of the scene that is everywhere detailed and coherent. How then do we represent a scene? It is argued here that focused attention provides spatiotemporal coherence for the stable representation of one object at a time. It is then argued that the allocation of attention can be co-ordinated to create a “virtual representation”. In such a scheme, a stable object representation is formed...

A set of visual search experiments tested the proposal that focused attention is needed to detect change. Displays were arrays of rectangles, with the target being the item that continually changed its orientation or contrast polarity. Five aspects of performance were examined: linearity of response, processing time, capacity, selectivity, and memory trace. Detection of change was found to be a self-terminating process requiring a time that increased linearly with the number of items in the display. Capacity for orientation was found to be about five items, a value comparable to estimates of attentional capacity. Observers were able to filter out both static and dynamic variations in irrelevant properties. Analysis also indicated a memory for previously attended locations. These results support the hypothesis that the process needed to detect change is much the same as the attentional process needed to detect complex static patterns. Interestingly, the features of orientation and polarity were found to be handled in somewhat different ways. Taken together, these results not only provide evidence that focused attention is needed to see change, but also show that change detection itself can provide new insights into the nature of attentional processing.

This study presents two experiments that examine how individuals learn relative directions between landmarks in a desktop virtual environment. Subjects were presented snapshot images of different virtual environments containing distinguishing landmarks and a road network. Following the presentation of each virtual environment, subjects were given a relative direction test. The relative direction test involved indicating the direction of hidden landmarks from different vantage points in the environment. Half of these vantage points were presented during the learning phase, while the other half were novel. Results showed that subjects learned relative directions between landmarks equally well when scenes were presented in either a sequential or random order. Furthermore, viewing a configuration of landmarks in a desktop virtual environment from multiple perspectives produced a viewpoint dependent representation in memory. Subjects had significantly greater response times for new viewing perspectives, as compared to previously viewed scenes. This viewpoint dependent representation of the environment persisted despite learning under conditions of spatio-temporal discontinuity and changes to an environmental frame of reference.