Premature ventricular contractions (PVCs) are abnormal heartbeats that begin in the lower ventricles or pumping chambers and disrupt the normal heart rhythm. The electrocardiogram (ECG) is the most often used tool for detecting abnormalities in the heart's electrical activity. PVCs are very frequent and usually harmless, but they can be extremely harmful in patients with significant heart problems. As a result, appropriate prevention combined with adequate treatment can improve patients' lives. This paper presents preliminary results on the main challenge associated with the detection of PVCs: identifying common patterns. The images used were extrapolated from the MIT-BIH Arrhythmia Database and then pre-processed to remove any signal noise before creating a distance matrix based on the wave distances of each pair of analyzed images. Finally, we clustered the distance into four groups using clustering algorithms such as K-means. We used a graph-based structure to graphically represent and explore cluster elements in this work. Preliminary results suggest the presence of four distinct patterns.

Abstract Head pose estimation represents an important computer vision technique in different contexts where image acquisition cannot be controlled by an operator, making face recognition of unknown subjects more accurate and efficient. In this work, starting from partitioned iterated function systems to identify the pose, different regression models are adopted to predict the angular value errors (yaw, pitch and roll axes, respectively). This method combines the fractal image compression characteristics, such as self-similar structures in order to identify similar head rotation, with regression analysis prediction. The experimental evaluation is performed on widely used benchmark datasets, i.e., Biwi and AFLW2000, and the results are compared with many existing state-of-the-art methods, demonstrating the robustness of the proposed fusion approach and excellent performance.

We present an approach to enable end-users to graphically compose their own applications directly on their mobile phone, mainly integrating the functionalities available on the device and those provided by pervasive and Internet services. To this aim, we propose a methodology and a graphical notation enabling the user to compose mobile applications, named MicroApps: the user creates an application following an incremental and iterative development process; he composes icons representing (pervasive) services mainly by touch-based selection and following a data-flow approach. He is not in charge of the creation of the user interface, which is automatically generated. The methodology enables the end-user to develop applications and/or compose services on the smartphone, so paving the way towards new scenarios where smartphones replace and overtake the Personal Computer, given their native possibility of wide connectivity, when augmented by features for interaction with remote systems and sensors. The methodology has been evaluated through an empirical analysis that revealed that in spite of the reduced size of the screen the use of the MicroApp Generator tool improves the effectiveness in terms of time and editing errors with respect to the use of MIT App Inventor [1] .

The visualization of information contained in reports is an important aspect of human-computer interaction, for both the accuracy and the complexity of relationships between data must be preserved. A greater attention has been paid to individual report visualization through different types of standard graphs (Histograms, Pies, etc.). However, this kind of representation provides separate information items and gives no support to visualize their relationships which are extremely important for most decision processes. This paper presents a design methodology exploiting the visual language CoDe based on a logic paradigm. CoDe allows to organize the visualization through the CoDe model which graphically represents relationships between information items and can be considered a conceptual map of the view. The proposed design methodology is composed of four phases: the CoDe Modeling and OLAP Operation pattern definition phases define the CoDe model and underlying metadata information, the OLAP Operation phase physically extracts data from a data warehouse and the Report Visualization phase generates the final visualization. Moreover, a case study on real data is provided.

Speaking in public may be a challenging task in terms of self-control and attention to the concepts to expose and to non-verbal communication. Presentation software, like Microsoft PowerPoint™ or OpenOffice, may support the speaker in organizing and controlling the flow of his/her discussion by commanding the slide change. In this paper we describe an approach exploiting the availability of the Microsoft Kinect™ advanced game controller to manage a presentation software through a Natural User Interface (NUI). The approach, named Kinect Presenter (KiP), adopts motion capture to recognize body gestures representing interaction metaphors. We perform a preliminary evaluation aiming at assessing the degree of support provided by the proposed interaction approach to the speaker activities. The assessment is based on the combined usage of two techniques: a questionnaire-based survey and an empirical analysis. The context of this study was constituted of Bachelor and PhD students in Computer Science at the University of Salerno, and teachers and employees from the same university. First results were adequate both in terms of satisfaction and performances, also when compared with a wireless mouse-based interaction approach.

As already documented in the literature, fractal image encoding is a family of techniques that achieves a good compromise between compression and perceived quality by exploiting the self-similarities present in an image. Furthermore, because of its compactness and stability, the fractal approach can be used to produce a unique signature, thus obtaining a practical image indexing system. Since fractal-based indexing systems are able to deal with the images in compressed form, they are suitable for use with large databases. We propose a system called FIRE, which is then proven to be invariant under three classes of pixel intensity transformations and under geometrical isometries such as rotations by multiples of /spl pi//2 and reflections. This property makes the system robust with respect to a large class of image transformations that can happen in practical applications: the images can be retrieved even in the presence of illumination and/or color alterations. Additionally, the experimental results show the effectiveness of FIRE in terms of both compression and retrieval accuracy.

We introduce the virtual image, an iconic index suited for pictorial information access in a pictorial database, and a similarity retrieval approach based on virtual images to perform content-based retrieval. A virtual image represents the spatial information contained in a real image in explicit form by means of a set of spatial relations. This is useful to efficiently compute the similarity between a query and an image in the database. We also show that virtual images support real-world applications that require translation, reflection, and/or rotation invariance of image representation.

This paper presents the software development workbench WSDW (Web structure-oriented Software Development Workbench) together with the tool development language TDL. WSDW is an integrated structure-oriented software environment which contains several tools for software evolution. The integration of tools is achieved by sharing a program representation which is based upon the mathematical concept of relation: the web structure is the basic high level representation of programs within the environment. The TDL language is a structure-oriented language that supports the creation of a wide variety of tools both for software development and maintenance. The elementary statements in a TDL program are web rewriting rules and manipulations of programs are expressed as web transformations. Moreover, to make program transformations more intuitive to the tool programmer, web rewriting rules are expressed graphically. Each tool in WSDW performs a sequence of web transformations and new software tools can be implemented as TDL programs and integrated into WSDW.

The paper presents a grammatical inference methodology for the generation of visual languages, that benefits from the availability of semantic information about the sample sentences. Several well-known syntactic inference algorithms are shown to obey a general inference scheme, which the authors call the Gen-Inf scheme. Then, all the algorithms of the Gen-Inf scheme are modified in agreement with the introduced semantics-based inference methodology. The use of grammatical inference techniques in the design of adaptive user interfaces was previously experimented with the VLG system for visual language generation. The system is a powerful tool for specifying, designing, and interpreting customized visual languages for different applications. They enhance the adaptivity of the VLG system to any visual environment by exploiting the proposed semantics-based inference methodology. As a matter of fact, a more general model of visual language generation is achieved, based on the Gen-Inf scheme, where the end-user is allowed to choose the algorithm which best fits his/her requirements within the particular application environment.

Introduces a variation of the 2D string representation for symbolic pictures, the non-redundant 2D string, and analyze it with respect to compactness and non-ambiguity. It results that the non-redundant 2D string is a more compact representation than the 2D string, and that the class of unambiguous pictures under the non-redundant 2D string is almost equal to the class of unambiguous pictures under the reduced 2D string, up to a special case. Moreover, we show that the compactness of the new index does not affect the time complexity of picture retrieval.>

The diagrammatic approach to user interfaces for computer-aided software development toolkits, visual query systems, and visual programming environments, is based on the use of diagrams and charts traditionally drawn on paper. In particular, the VLG system (Visual Language Generator) has been proposed to generate icon-oriented visual languages customized for given applications. The syntactical model underlying the interpretation of a visual language in VLG has been designed to describe icon-oriented visual languages. In order to enable the VLG system to apply to any kind of graphical languages, like diagrammatic ones, it is necessary to find a more general syntactical model able to support both their generation and interpretation. This paper addresses the comprehension of the features that a grammatical formalism for nonlinear languages must have to match any requirement for an efficient parsing. To this aim, relation grammars support an easy implementation of a general parsing algorithm for multidimensional languages, parametric with respect to the rewriting rules of the grammar. We compare the expressive power of relation grammars to grammatical formalisms for graph grammars.>

This paper presents the architecture and some tools of the software development workbench WSDW. The authors propose a structure-oriented workbench, in which interactive software tools are integrated through sharing a unique high level program representation, satisfying the request of independence from the source language. The data structure representing programs, the web structure, is based upon the mathematical concept of relation and it is easily implemented as a Prolog data base. Program transformations, given as web transformations, can be expressed as rewriting rules, so that software tools can be implemented as sets of rewriting rules and then added to the WSDW.>

A system to generate and interpret customized visual languages in given application areas is presented. The generation is highly automated. The user presents a set of sample visual sentences to the generator. The generator uses inference grammar techniques to produce a grammar that generalizes the initial set of sample sentences, and exploits general semantic information about the application area to determine the meaning of the visual sentences in the inferred language. The interpreter is modeled on an attribute grammar. A knowledge base, constructed during the generation of the system, is then consulted to construct the meaning of the visual sentence. The architecture of the system and its use in the application environment of visual text editing (inspired by the Heidelberg icon set) enhanced with file management features are reported.>