DefibViz: A Visualization Tool for the Assessment of Electrode Parameters on Transthoracic Defibrillation Thresholds

DefibViz is a software application developed for defibrillation simulation and visualization. It exploits both surface techniques and methods for the interactive exploration of volumetric datasets for the analysis of transthoracic defibrillation simulation results. DefibViz has a graphical user interface for the specification of the shape, size, position, and applied voltage of a defibrillator's electrodes. An option is provided for using 3D slice plane widgets, which operate on the volumetric datasets, such that the distribution of the voltage gradient induced by an electric shock can be visually inspected in various tissues throughout the myocardium and torso. One goal of DefibViz is to enhance understanding of how electrode parameters relate to the change of the voltage gradient distribution throughout the heart, which may help lead to optimal defibrillator design. DefibViz is significant, in that, it is built by using an open-source graphics and visualization framework providing a platform for subsequent modifiability and extensibility. Moreover, it integrates simulation and visualization techniques, which previously required the running of several independent software executables, into an enhanced, seamless, and comprehensive software application.     

A knowledge-based framework for intelligent-data migration

Abstract: The Object-Inferencing Framework (OIF) is a knowledge-based system developed for intelligent-data migration. The framework provides a mechanism to integrate relational data which represents a source model; a project-specific rulebase which specifies plausible migration scenarios; and a deduction system to facilitate the migration of source data to a new, complex target model. Typically, the target model includes constituents that possess both graphic and tabular components. Although the framework is experimental, industrial applications built upon OIF have been successfully deployed in scenarios in which the source data contained implicit information in that semantic relationships and structure conveyed by the data had to be inferred by a domain expert. This framework provides a substrate for migration from any unstructured or semi-structured data representation to a complex, semantically rich target data model. Examples of the migration of CAD data, which represents an electrical-distribution system, to a client-server based Automated Mapping/Facilities Management (AM/FM) platform are presented to convey the salient features of the design and utility of the OIF. Even though the examples are taken from a specific domain, the approach has potential applications in a myriad of domains, including business enterprises in which the migration of data created and managed by legacy systems to object-oriented and clientserver environments is an area of intense research and development.     

DefibViz: a visualization tool for the assessment of electrode parameters on transthoracic defibrillation thresholds

DefibViz is a software application developed for defibrillation simulation and visualization. It exploits both surface techniques and methods for the interactive exploration of volumetric datasets for the analysis of transthoracic defibrillation simulation results. DefibViz\ has a graphical user interface for the specification of the shape, size, position, and applied voltage of a defibrillator's electrodes. An option is provided for using 3-D slice plane widgets, which operate on the volumetric datasets, such that the distribution of the voltage gradient induced by an electric shock can be visually inspected in various tissues throughout the myocardium and torso. One goal of DefibViz is to enhance understanding of how electrode parameters relate to the change of the voltage gradient distribution throughout the heart, which may help lead to optimal defibrillator design. DefibViz; is significant, in that, it is built by using an open-source graphics and visualization framework providing a platform for subsequent modifiability and extensibility. Moreover, it integrates simulation and visualization techniques, which previously required the running of several independent software executables, into an enhanced, seamless, and comprehensive software application.     

A pedagogical approach to database design via Karnaugh maps

The study of normalization is a fundamental topic that is covered in most introductory database courses taught by departments of Computer/Electrical Engineering and Computer Science. The typical pedagogical approach to normalization presents several classical algorithms, which are based upon the application of axioms and lemmas for manipulating functional dependencies, that can be used in the process of relational decomposition and synthesis. In this paper, an augmentation to the traditional pedagogical strategy is presented for introducing students to normalization and relational synthesis concepts. This augmentation transforms semantic concepts into Boolean form that can be easily manipulated with the Karnaugh map. The Karnaugh map provides an especially useful method for illustrating the process of determining the candidate keys of a relation, as well as simplifying the mechanics of manipulating functional dependencies that are required for database decomposition and synthesis. Moreover, students find the Karnaugh-map-based techniques faster for most calculations, as well as easier to apply than conventional algorithms, since most engineering students are more familiar with combinatorial Boolean algebra than the algebra of functional relations     

A Polymorphism at the Translation Start Site of the Vitamin D Receptor Gene Is Associated with the Response to Anti-Osteoporotic Therapy in Postmenopausal Women from Southern Italy

The present study investigated the effect of two single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) gene, rs1544410 A/G and rs2228570 C/T, in modulating bone mineral density (BMD) and the response to treatment with bisphosphonates or strontium ranelate in postmenopausal osteoporosis (PMO). Four hundred eighteen postmenopausal women from Southern Italy treated with bisphosphonates or strontium ranelate for three years were enrolled and stratified according to their genotype. Changes in BMD were expressed as the delta t-score (Δt-score). Allelic frequencies for rs1544410 A/GSNP were 11.2% AA, 50.0% GA and 38.8% GG; for rs2228570 C/TSNP were 54.8% CC, 39.5% TC and 5.7% TT. TT carriers showed a lower t-score than TC and CC (both p < 0.02) genotypes and were more responsive to the therapy when compared to both TC (p < 0.02) and CC (p < 0.05) carriers. Specifically, TT carriers receiving alendronate demonstrated a significant improvement of the Δt-score compared to TC and CC (both p < 0.0001) carriers. After adjustment for confounders, the Δt-score showed evidence of a statistically significant positive association with TT in all treatments considered. Therapy response was independent of rs1544410 A/G SNP; instead, rs2228570 C/TSNP was associated with a better response to antiresorptive treatment, thus suggesting that the therapy for PMO should be personalized.     

A function-centered framework for reasoning about system failure at multiple levels of abstraction

This paper presents the knowledge organization for a simulation subsystem that is a component of a comprehensive expert system for failure modes and effects analysis. Organizing the simulation subsystem's knowledge base around a function-centered ontology produces an architecture that facilitates reasoning about an engineering design at multiple levels of abstraction and throughout the life-cycle of the design. Moreover, the resulting architecture provides the capability for incorporating computer-aided analysis and design tools early on into the conceptual design of an engineering system before a commitment is made to a specific technology to implement the system's behavior. The result is an expert system simulation knowledge source that can be used to reason about the effects of system failures based on conceptual designs, i.e. designs in which commitments to an underlying technology to achieve the system's function have not yet been made but computer-aided assistance for reasoning about the system's potential failure modes and effects is useful.     

A Prolog-based centroid algorithm for isovolume extraction from finite element torso simulations.

Computer modeling and simulation of the human torso provides a rapid and non-invasive means to observe the effects of implanted defibrillators. The objective of this study was to improve a method of extracting data from an implanted defibrillator simulation for subsequent visualization. Electrical quantities, such as the potential and gradient fields, are computed at points throughout various regions of a three-dimensional (3-D) torso model via a finite element solution. Software is then implemented in the Prolog language to extract and visualize a subset of the data, from within any subregion of the model, satisfying a given declarative constraint. In past work, membership in these subsets had been determined solely by the electrical quantities at the vertices of the tetrahedral elements within the model along with an arbitrary choice made by the user. However, this study expands upon previous work to utilize an alternative means of classification, calculating the centroid of each tetrahedron and assigning electrical properties to these centroids based on the distances of each centroid to the four corners of the tetrahedron. After the modifications, it is expected that the extracted subsets of the model will represent the data in a more realistic and conservative manner and provide more insight into the process of defibrillation than previous methods of data extraction and visualization.     

Extracting isovolumes from three-dimensional torso geometry usingPROLOG

Three-dimensional (3D) finite element torso models are widely used to simulate defibrillation field quantities, such as potential, gradient and current density. These quantities are computed at spatial nodes that comprise the torso model. These spatial nodes typically number between 10⁵ and 10⁶, which makes the comprehension of torso defibrillation simulation output difficult. Therefore, the objective of this study is to rapidly prototype software to extract a subset of the geometric model of the torso for visualization in which the nodal information associated with the geometry of the model meets a specified threshold value (e.g., minimum gradient). The data extraction software is implemented in PROLOG, which is used to correlate the coordinate, structural and nodal data of the torso model. A PROLOG-based environment has been developed and is used to rapidly design and test new methods for sorting, collecting and optimizing data extractions from defibrillation simulations in a human torso model for subsequent visualization