0000000000067426
AUTHOR
Fernando Barber
Automatic estimation of Purkinje-Myocardial junction hot-spots from noisy endocardial samples: A simulation study
The reconstruction of the ventricular cardiac conduction system (CCS) from patient-specific data is a challenging problem. High-resolution imaging techniques have allowed only the segmentation of proximal sections of the CCS from images acquired ex vivo. In this paper, we present an algorithm to estimate the location of a set of Purkinje-myocardial junctions (PMJs) from electro-anatomical maps, as those acquired during radio-frequency ablation procedures. The method requires a mesh representing the myocardium with local activation time measurements on a subset of nodes. We calculate the backwards propagation of the electrical signal from the measurement points to all the points in the mesh …
Simulating socially intelligent agents in semantic virtual environments
AbstractThe simulation of synthetic humans inhabiting virtual environments is a current research topic with a great number of behavioral problems to be tackled. Semantical virtual environments (SVEs) have recently been proposed not only to ease world modeling but also to enhance the agent–object and agent–agent interaction. Thus, we propose the use of ontologies to define the world’s knowledge base and to introduce semantic levels of detail that help the sensorization of complex scenes—containing lots of interactive objects. The object taxonomy also helps to create general and reusable operativity for autonomous characters—for example, liquids can be poured from containers such as bottles. …
Automatic Location of Sources of Electrical Activation from Electroanatomical Maps
Electro-anatomical mapping is a widely used technique used by electrophysiologists to understand patient's activation pattern. The system measures activation time at different locations but does not provide information on underlying electrical pathways or triggering points, such as Purkinje-myocardial junctions or ectopic foci. We present a method to estimate the locations of Purkinje-myocardial junctions from a discrete set of endocardial samples. Using less than 1000 endocardial samples it can recover locations and activation times of the most influencing Purkinje myocardial junctions from Purkinje trees of up to 500 junctions. A simulation study revealed that using the estimated Purkinje…
Coordination and Sociability for Intelligent Virtual Agents
This paper presents a multi-agent framework designed to simulate synthetic humans that properly balance task oriented and social behaviors. The work presented in this paper focuses on the social library integrated in BDI agents to provide socially acceptable decisions. We propose the use of ontologies to define the social relations within an artificial society and the use of a market based mechanism to reach sociability by means of task exchanges. The social model balances rationality, to control the global coordination of the group, and sociability, to simulate relations (e.g. friendliness) and reciprocity among agents. The multi-agent framework has been tested successfully in dynamic envi…
Sociable Behaviors in Virtual Worlds
When simulating three-dimensional environments populated by virtual humanoids, immersion requires the simulation of consistent social behaviors to keep the attention of the user/s while displaying realistic scenes. However, intelligent virtual actors still lack a kind of collective or social intelligence necessary to reinforce the roles they are playing in the simulated environment (e.g. a waiter, a guide, etc). Decision making for virtual agents has been traditionally modeled under self interested assumptions, which are not suitable for social multi-agent domains. Instead, artificial society models should be introduced to provide virtual actors with socially acceptable decisions, which are…
Discovering temporal relationships in databases of newspapers
This paper is mainly dedicated to analyse the problem of discovering frequent temporal patterns in event sequences extracted from a large repository of newspapers. The proposed formalism and algorithms rely on Toodor, which is a document retrieval system that allows users to specify conditions over the structure, contents and temporal features of the stored documents. We develop in this work several algorithms for recognising frequent temporal patterns in terms of arc-consistency, which consist of discarding temporal occurrences that do not satisfy a temporal structure.
A J-MADeM Agent-Based Social Simulation to Model Urban Mobility
The mobility models followed within metropolitan areas, mainly based on the massive use of the car instead of the public transportation, will soon become unsustainable unless there is a change of citizens’ minds and transport policies. The main challenge related to urban mobility is that of getting free-flowing greener cities, which are provided with a smarter and accessible urban transport system. In this paper, we present an agent-based social simulation approach to tackle this kind of social-ecological systems. The Jason Multi-modal Agent Decision Making (JMADeM) library enable us to model and implement the social decisions made by each habitant about how to get to work every day, e.g., …
J-MADeM, a market-based model for complex decision problems
This paper presents J-MADeM, a multi-modal decision making mechanism to provide agents in a Multi-Agent Systems (MAS) with a market-based model for complex decision problems. J-MADeM is now available as an open source library fully integrated into Jason, the successful interpreter for the AgentSpeak programming language. The aim of this work is to improve Jason by incorporating an agent decision-making module able to merge multiple information sources received from the rest of the agents. This information is modeled as a set of utility functions expressing the preferences of the agents for a specific problem. Then, J-MADeM agents use one-round sealed-bid combinatorial auctions as the main p…
Multiagent System for Detecting and Solving Design-Time Conflicts in Civil Infrastructure
One typical source of problems in the Civil Infrastructure domain is the distributed and collaborative nature of the projects in which different profiles of engineers contribute with designs devoted to the interest of their field of expertise. Thus, situations in which there are different conflicts of interests are quite common. A conflict refers to a situation in which the actions of an engineer collide with the interests of other engineers. In this paper, we present a multi-agent system that, thanks to the use of ontologies and rules on those ontologies, is able to detect profilespecific conflict situations and solve them according to the preferences of the parties involved in the conflic…
A Multiagent Framework to Animate Socially Intelligent Agents
This paper presents a multiagent framework designed to animate groups of synthetic humans that properly balance task oriented and social behaviors. The work presented in this paper focuses on the BDI agents and the social model integrated to provide socially acceptable decisions. The social model provides rationality, to control the global coordination of the group, and sociability, to simulate relations (e.g. friends) and reciprocity between members. The multiagent based framework has been tested successfully in dynamic environments while simulating a virtual university bar, where several types of agents (groups of waiters and customers) can interact and finally display complex social beha…
An efficient synthetic vision system for 3D multi-character systems
This poster deals with the problem of sensing virtual environments for 3D intelligent multi-character simulations. As these creatures should display reactive skills (navigation or gazing), together with the necessary planning processes, required to animate their behaviours, we present an efficient and fully scalable sensor system designed to provide this information (low level + high level) to different kinds of 3D embodied agents (games, storytelling, etc).
Integrating miniMin-HSP agents in a dynamic simulation framework
In this paper, we describe the framework created for implementing AI-based animations for artificial actors in the context of IVE (Intelligent Virtual Environments). The minMin-HSP (Heuristic Search Planner) planner presented in [12] has been updated to deal with 3D dynamic simulation environments, using the sensory/actuator system fully implemented in UnrealTM and presented in [10]. Here, we show how we have integrated these systems to handle the necessary balance between the reactive and deliberative skills for 3D Intelligent Virtual Agents (3DIVAs). We have carried out experiments in a multi-agent 3D blocks world, where 3DIVAs will have to interleave sensing, planning and execution to be…
Integrating Social Skills in Task-Oriented 3D IVA
This paper presents a set of mechanisms oriented to incorporate social information into the decision taking of task-oriented 3DIVA. The aim of this approach is to integrate collaborative skills in different character's roles (seller/buyer, worker, pedestrian, etc.) in order to enhance its behavioral animation. The collective intelligence expected in this kind of multi-character domains (e.g. storytelling, urban simulation, interactive games, etc.) requires agents able to dialogue/interact with other characters, to autonomously group/ungroup (according to their goals), or to distribute tasks and coordinate their execution for solving possible conflicts. The social model implemented follows t…
Estimation of Location and Activation Time of Purkinje Myocardial Junctions from Sparse and Noisy Endocardial Electrical Samples
The activation of the myocardial muscle is triggered by Purkinje-myocardial junctions (PMJs), which are the terminal sites of the specialised cardiac conduction system (CCS). Obtaining the location of the PMJs and other sources of endocardial ectopic activity would be desirable for building computer models of cardiac electrophysiology and planning ablation interventions. We present a method to estimate the location and activation times of endocardial electrical sources in a 3D model of the ventricles. The algorithm requires a set of discrete electrical samples on the endocardium, which can include errors in location and activation time. The estimated sources are properly placed with a locat…
Estimation of Personalized Minimal Purkinje Systems From Human Electro-Anatomical Maps
The Purkinje system is a heart structure responsible for transmitting electrical impulses through the ventricles in a fast and coordinated way to trigger mechanical contraction. Estimating a patient-specific compatible Purkinje Network from an electro-anatomical map is a challenging task, that could help to improve models for electrophysiology simulations or provide aid in therapy planning, such as radiofrequency ablation. In this study, we present a methodology to inversely estimate a Purkinje network from a patient's electro-anatomical map. First, we carry out a simulation study to assess the accuracy of the method for different synthetic Purkinje network morphologies and myocardial junct…
A Saturation Avoidance Technique for Peer-to-Peer Distributed Virtual Environments
This paper presents a multi-agent framework oriented to animate groups of synthetic humans that properly balance task-oriented and social behaviors. We mainly focus on the social model designed for BDI-agents to display socially acceptable decisions. This model is based on an auction mechanism used to coordinate the group activities derived from the character's roles. The model also introduces reciprocity relations between the members of a group and allows the agents to include social tasks to produce realistic behavioral animations. Furthermore, a conversational library provides the set of plans to manage social interactions and to animate from simple chats to more complex negotiations. Th…
Inverse estimation of terminal connections in the cardiac conduction system
Modeling the cardiac conduction system is a challenging problem in the context of computational cardiac electrophysiology. Its ventricular section, the Purkinje system, is responsible for triggering tissue electrical activation at discrete terminal locations, which subsequently spreads throughout the ventricles. In this paper, we present an algorithm that is capable of estimating the location of the Purkinje system triggering points from a set of random measurements on tissue. We present the properties and the performance of the algorithm under controlled synthetic scenarios. Results show that the method is capable of locating most of the triggering points in scenarios with a fair ratio bet…
Social Animation in Complex Environments
This work presents a market-based social model to produce good quality behavioral animations for groups of intelligent virtual agents. The social model coordinates the activities of groups of virtual characters and also includes social actions in the agent decision-making. We follow the Multi-Agent Resource Allocation approach presented in [2], where agents express their preferences using utility functions. The dynamics of social interactions is inspired by the theory of Piaget [3] over which we have implemented reciprocal task exchanges.