Miguel Lozano

Miguel Lozano
University of Valencia | UV · Department of Computer Science

phD in Computer Science

About

106
Publications
13,192
Reads
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694
Citations
Citations since 2016
37 Research Items
323 Citations
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201620172018201920202021202201020304050
201620172018201920202021202201020304050
201620172018201920202021202201020304050
Introduction
Miguel Lozano currently works at the Department of Computer Science, University of Valencia. Miguel does research in Bio-medical Engineering, Machine Learning and Computer Engineering. Their current projects are 'e3DTorso', ECTOPIC's foci location and Aorta's reconstruction and population modelling.
Additional affiliations
January 2003 - December 2011
Universitat de València

Publications

Publications (106)
Article
Full-text available
In order to determine the site of origin (SOO) in outflow tract ventricular arrhythmias (OTVAs) before an ablation procedure, several algorithms based on manual identification of electrocardiogram (ECG) features, have been developed. However, the reported accuracy decreases when tested with different datasets. Machine learning algorithms can automa...
Article
Full-text available
Personalized cardiac electrophysiology simulations have demonstrated great potential to study cardiac arrhythmias and help in therapy planning of radio-frequency ablation. Its application to analyze vulnerability to ventricular tachycardia and sudden cardiac death in infarcted patients has been recently explored. However, the detailed multi-scale b...
Article
Full-text available
The combination of machine learning methods together with computational modeling and simulation of the cardiovascular system brings the possibility of obtaining very valuable information about new therapies or clinical devices through in-silico experiments. However, the application of machine learning methods demands access to large cohorts of pati...
Chapter
The ellipse can be an appropriate geometry for aorta cross-section fitting on the lumen contour. However, in some regions of the aorta, such as the Sinuses of Valsalva, this approximation can suffer of a relatively high error. Thus, some authors use closed polynomial curves for a better representation of the cross section. This paper presents a det...
Chapter
Full-text available
Patients that have suffered a myocardial infarction are at lifetime high risk for sudden cardiac death (SCD). Personalized 3D computational modeling and simulation can help to find non-invasively arrhythmogenic features of patients’ infarcts, and to provide additional information for stratification and planning of radiofrequency ablation (RFA). Cur...
Article
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 simu...
Article
Full-text available
Reinforcement learning is one of the most promising machine learning techniques to get intelligent behaviors for embodied agents in simulations. The output of the classic Temporal Difference family of Reinforcement Learning algorithms adopts the form of a value function expressed as a numeric table or a function approximator. The learned behavior i...
Presentation
Full-text available
Muestra los excelentes resultados académicos de los estudiantes con perfil biológico en las asignaturas informáticas del Máster en Bioinformática de la UV. https://www.uv.es/bioinfor/.
Article
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...
Article
Full-text available
Introduction: Focal atrial tachycardia is commonly treated by radio frequency ablation with an acceptable long-term success. Although the location of ectopic foci tends to appear in specific hot-spots, they can be located virtually in any atrial region. Multi-electrode surface ECG systems allow acquiring dense body surface potential maps (BSPM) for...
Article
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 algorit...
Article
Full-text available
Modeling pedestrian dynamics and their implementation in a computer are challenging and important issues in the knowledge areas of transportation and computer simulation. The aim of this article is to provide a bibliographic outlook so that the reader may have quick access to the most relevant works related to this problem. We have used three main...
Conference Paper
Full-text available
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...
Article
Full-text available
Non-invasive localization of continuous atrial ectopic beats remains a cornerstone for the treatment of atrial arrhythmias. The lack of accurate tools to guide electrophysiologists leads to an increase in the recurrence rate of ablation procedures. Existing approaches are based on the analysis of the P-waves main characteristics and the forward bod...
Data
P-wave morphologies registered for the 57 ectopic sites plus de SAN. Position of the precordial leads on the torso surface and P-wave morphology registered at V1 (blue), V3 (red) and V5 (green) for the sites stimulated on RA (30 sites plus SAN) and the sites stimulated on LA (27 sites). The doted purple square, for example, identifies the P-waves r...
Data
Validation of the atrial and torso models comparing the experimental activations with the simulations carried out by activating ectopic foci at the same sites. a) Local activation times (LATs) computed by activating the SAN, and the 17 RA sites (upper panel) defined in [8] and at the 14 LA sites (lower panel) defined in [10,11]. Bluish colours corr...
Data
Anatomical sites of the atrial ectopic foci. 58 ectopic foci (including the SAN) grouped by RA and LA segment locations. The first 17 and 14 sites on RA and LA respectively (31 sites in total) were placed at the same positions used in previous experimental studies [8,10]. The additional 13 sites on each atrium (26 sites in total) were randomly sele...
Article
Full-text available
This paper analyzes the emergent behaviors of pedestrian groups that learn through the multiagent reinforcement learning model developed in our group. Five scenarios studied in the pedestrian model literature, and with different levels of complexity, were simulated in order to analyze the robustness and the scalability of the model. Firstly, a redu...
Conference Paper
Full-text available
Multi-electrode surface ECG systems allow to acquire dense body surface potential maps (BSPM) with the aim of improving diagnosis of cardiac arrhythmias. However, it is difficult to relate biomark-ers based on the BSPM with arrhythmic events that occur in the atria. We have developed a machine learning based pipeline to associate a BSPM with a mini...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
Modeling the cardiac conduction system is a challenging problem in the context of computational cardiac electrophysiology. Its main structure in the ventricles is the Purkinje system, which is responsible for triggering heart contraction. Since it cannot be visualized by means of medical imaging techniques, it is commonly neglected or inversely est...
Article
Full-text available
A new multi-agent reinforcement learning approach is introduced for the simulation of pedestrian groups. The embodied agents learn by interacting with the environment. They must learn to control their velocity, avoiding obstacles and the other pedestrians to reach a goal (a spatial position) inside the virtual environment. A new methodology is prop...
Chapter
The governance requires technical support regarding the complexity in deciding health policies to assist people who require long-term care. Long-term care policies require the use of ICT simulation tools that can provide policy makers with the option of going into a decision theatre and virtually knowing the consequences of different policies prior...
Article
Full-text available
Pedestrian simulation is complex because there are different levels of behavior modeling. At the lowest level, local interactions between agents occur; at the middle level, strategic and tactical behaviors appear like overtakings or route choices; and at the highest level path-planning is necessary. The agent-based pedestrian simulators either focu...
Conference Paper
Full-text available
In this work, a Multi-agent Reinforcement Learning framework is used to generate simulations of virtual pedestrians groups. The aim is to study the influence of two different learning approaches in the quality of generated simulations. The case of study consists on the simulation of the crossing of two groups of embodied virtual agents inside a nar...
Article
Full-text available
In this paper, we propose a simulator for integrated long-term care systems using as a starting point a holistic model of care systems for people that need long term care, the Sustainable Socio-Health Model (SSHM). The implementation of the simulator on the Jason multi-agent platform allows the tool to include the human interactions, preferences, a...
Article
Full-text available
Multiagent platforms need to be evaluated focusing on the underlying computer architecture in order to allow developers to exploit the parallelism available in multicore processors. This paper presents the characterization of Jason, a well-known Java-based multiagent platform, when executed on distributed shared memory architectures. Since this kin...
Article
Full-text available
Multiagent platforms need to be evaluated focusing on the underlying computer architecture in order to allow developers to exploit the parallelism available in multicore processors. This paper presents the characterization of Jason, a well-known Java-based multiagent platform, when executed on distributed shared memory architectures. Since this kin...
Article
Interactive applications like crowd simulations need to properly render the virtual world while simulating the interaction of thousands of agents at the same time. The computational workload generated by these two tasks highly increases with the number simulated agents, requiring a scalable design of the multiagent system. In this paper we present,...
Chapter
Full-text available
The governance requires technical support regarding the complexity in deciding health policies to assist people who require long-term care. Long-term care policies require the use of ICT simulation tools that can provide policy makers with the option of going into a decision theatre and virtually knowing the consequences of different policies prior...
Article
Full-text available
The computing capabilities of current multi-core and many-core architectures have been used in crowd simulations for both enhancing crowd rendering and simulating continuum crowds. However, improving the scalability of crowd simulation systems by exploiting the inherent parallelism of these architectures is still an open issue. In this paper, we pr...
Conference Paper
Full-text available
In this paper, the calibration of a framework based in Multi-agent Reinforcement Learning (RL) for generating motion simulations of pedestrian groups is presented. The framework sets a group of autonomous embodied agents that learn to control individually its instant velocity vector in scenarios with collisions and friction forces. The result of th...
Article
Full-text available
Metropolitan mobility models, 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 accessibl...
Article
Full-text available
In this paper we present experiments with search-based planning as the most generic description of intelligent behaviour for virtual actors. Using a MinMin heuristic search-based planner (HSP), we demonstrate how this can be used to generate efficient plans (in terms of plan length), and how the production of these minimum length plans is performed...
Article
The Read-Copy Update (RCU) synchronization method was designed to cope with multiprocessor scalability some years ago, and it was included in the Linux kernel October of 2002. Recently, libraries providing user-space access to this method have been released, although they still have not been used in complex applications. In this paper, we propose t...
Article
Full-text available
The simulation of large crowds of autonomous agents with a realistic behavior is still a challenge for several computer research communities. Distributed architectures can provide scalability to crowd simulations, but they require the use of efficient partitioning methods. Although convex hulls have been shown as very efficient structures for crowd...
Article
The visualization system of large-scale crowd simulations should scale up with both the number of visuals (views of the virtual world) and the number of agents displayed in each visual. Otherwise, we could have large scale crowd simulations where only a small percentage of the population is displayed. Several approaches have been proposed in order...
Conference Paper
Full-text available
In this paper we introduce a Multi-agent system that uses Reinforcement Learning (RL) techniques to learn local navigational behaviors to simulate virtual pedestrian groups. The aim of the paper is to study empirically the validity of RL to learn agent-based navigation controllers and their transfer capabilities when they are used in simulation env...
Article
Full-text available
This article presents J-MADeM, a multi-modal decision making mechanism to provide agents in a Multi-Agent System (MAS) with a market-based model for complex decision problems. The model is basically based on a set of utility functions, expressing the preferences of the agents for a specific problem, and a one-round sealed-bid combinatorial auction...
Conference Paper
Full-text available
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 wi...
Conference Paper
Full-text available
Java-based simulation environments are currently used by many multiagent systems (MAS), since they mainly provide portability as well as an interesting reduction of the development cost. However, this kind of MAS are rarely considered when developing interactive applications with time response constraints. This paper analyses the performance provid...
Conference Paper
Full-text available
The current challenge for crowd simulations is the design and development of a scalable system that is capable of simulating the individual behavior of millions of complex agents populating large scale virtual worlds with a good frame rate. In order to overcome this challenge, this thesis proposes different improvements for crowd simulations. Concr...
Chapter
Full-text available
The huge number of cores existing in current Graphics Processor Units (GPUs) provides these devices with computing capabilities that can be exploited by distributed applications. In particular, these capabilites have been used in crowd simulations for enhancing the crowd rendering, and even for simulating continuum crowds. However, GPUs have not be...
Article
The simulation of large crowds of autonomous agents with realistic behavior is still a challenge for several computer research communities. In order to handle large crowds, some scalable architectures have been proposed. Nevertheless, the effective use of distributed systems requires the use of partitioning methods that can properly distribute the...
Conference Paper
Full-text available
Large-scale crowd simulations require distributed computer architectures and efficient parallel techniques to achieve the rendering of visually plausible images while simulating the behaviour of crowds of autonomous agents. The Java-based multiagent platforms, devoted to provide the agents with the required lifecycle, rep- resent a key middleware i...
Conference Paper
Full-text available
This paper presents a Q-Learning-based multiagent system oriented to provide navigation skills to simulation agents in virtual environments. We focus on learning local navigation behaviours from the interactions with other agents and the environment. We adopt an environment-independent state space representation to provide the required scalability...