Alejandro Rodríguez

The effect of the asymmetry of road transportation networks on the traveling salesman problem

The routing of vehicles on road transportation networks is an area of great importance to transportation planners within scientific literature. This field includes well known and studied problems like traveling salesman problems or TSP or the more realistic asymmetric variant or ATSP, whose applications extend to other areas of transport and operations research. This work studies the effect that the asymmetry of road transportation networks, geographical location and territory have over TSP and ATSP methods. We conduct comprehensive experiments in order to assess the effects that these factors have on some of the best known algorithms for the TSP/ATSP. We demonstrate that all these factors have a significant influence in solution time and quality. Furthermore, we show that the solutions obtained with Euclidean matrices and those obtained with real distance matrices differ significantly.

A VR-Based Serious Game for Studying Emotional Regulation in Adolescents

People all use more or less adapted strategies to confront adverse emotional situations in their lives without being psychologically affected. The emotional regulation (ER) strategies that we use determine the way in which we feel, express, and behave. Moreover, ER strategies are particularly important in adolescents, a population for which ER strategy deficits can be linked to the appearance of numerous mental health disorders, such as depression or anxiety, or disruptive behaviors. Thus, the early detection of dysfunctional ER strategies and training in adaptive ER strategies can help prevent future occurrences of possible behavioral and psychosocial disorders. In this article, the authors present the GameTeen System (GT-System), a novel instrument based on virtual reality and serious games for the assessment and training of ER strategies in adolescents. The results of their preliminary evaluation suggest that this system can effectively train and evaluate emotional regulation strategies in adolescents.

A study on the effect of the asymmetry on real capacitated vehicle routing problems

Matrices with distances between pairs of locations are essential for solving vehicle routing problems like the Capacitated Vehicle Routing Problem (CVRP), Traveling Salesman Problem (TSP) and others. This work deals with the complex reality of transportation networks and asymmetry. Through a series of comprehensive and thorough computational and statistical experiments we study the effect that many factors like asymmetry, geographical location of the depot and clients, demand, territory and maximum vehicle capacity have in the solution of CVRP instances. We examine both classical heuristics as well as current state-of-the-art metaheuristics and show that these methods are seriously affected by the studied factors from a solution time and quality of solutions perspective. We systematically compare the solutions obtained in the symmetric scenario with those obtained in the real asymmetric case at a quantitative as well as a qualitative level, with the objective of carefully measuring and understanding the differences between both cases.

How the physical similarity of avatars can influence the learning of emotion regulation strategies in teenagers

Greater emotion regulation when observing a physically similar avatar.Greater frustration induction when observing a physically similar avatar.Greater physical identification with physically similar avatar.Significant change in brain when observing a physically similar avatar. The aim of this study is to evaluate the influence of the physical similarity of avatars with the user on emotion regulation strategy training. In this study twenty-four teenagers observed an avatar (either physically similar to the participant or neutral) that gets frustrated with his/her computer, after which he/she applies an emotion regulation strategy (slow breathing). The intensity of the emotional induction and regulation processes was measured using questionnaires and electroencephalogram data. The results show that observing an avatar that is physically similar to the participant has a significantly greater impact on emotional valence and arousal in participants and also induces emotional states that are significantly more intense than when observing a neutral avatar. The results seem to indicate significantly greater activation of specific brain regions that are related to these processes and greater identification with the avatar in terms of both subjective and objective measures in participants that observed an avatar that was physically similar to them. However, there were no significant differences in the sense of presence or the appeal (i.e., satisfaction) to participants regarding the virtual environment. The use of avatars in mental health applications is relatively new and its specific influence is still unknown. We consider this study to be a first step forward in better understanding the use of avatars in mental health applications for youth. This research brings new guidelines to the design of different types of applications in this field in order to achieve greater behavioral changes in youth.

GameTeen: new tools for evaluating and training emotional regulation strategies.

The aim of this paper is to describe GameTeen, a novel instrument for the assessment and training of Emotional Regulation (ER) strategies in adolescent population. These new tools are based on the use of 3D serious games that can be played under different settings. The evolution of ER strategies will be monitored in two ways depending on the setting where the tool is presented. Firstly, in the laboratory, physiological signals and facial expressions of participants will be recorded. Secondly, in real life settings, ecological momentary assessment tools will be used to obtain answers from the subjects using their mobile phone. The goal is to obtain more attractive and reliable tools to evaluate and train ER strategies.

Altered cerebral blood flow velocity features in fibromyalgia patients in resting-state conditions

The aim of this study is to characterize in resting-state conditions the cerebral blood flow velocity (CBFV) signals of fibromyalgia patients. The anterior and middle cerebral arteries of both hemispheres from 15 women with fibromyalgia and 15 healthy women were monitored using Transcranial Doppler (TCD) during a 5-minute eyes-closed resting period. Several signal processing methods based on time, information theory, frequency and time-frequency analyses were used in order to extract different features to characterize the CBFV signals in the different vessels. Main results indicated that, in comparison with control subjects, fibromyalgia patients showed a higher complexity of the envelope CBFV and a different distribution of the power spectral density. In addition, it has been observed that complexity and spectral features show correlations with clinical pain parameters and emotional factors. The characterization features were used in a lineal model to discriminate between fibromyalgia patients and healthy controls, providing a high accuracy. These findings indicate that CBFV signals, specifically their complexity and spectral characteristics, contain information that may be relevant for the assessment of fibromyalgia patients in resting-state conditions.

Using Portable EEG Devices to Evaluate Emotional Regulation Strategies during Virtual Reality Exposure

As Virtual Reality (VR) is starting to be used to train emotional regulation strategies, it would be interesting to propose objective techniques to monitor the emotional reactions of participants during the virtual experience. In this work, the main goal is to analyze if portable EEG systems are adequate to monitor brain activity changes caused by the emotional regulation strategies applied by the participants. The EEG signals captured from subjects that navigate through a virtual environment designed to induce a negative mood will be compared between three experimental groups that will receive different instructions about the emotional regulation strategies to apply. The study will allow us to validate the possibilities of portable EEG devices to monitor emotional regulation strategies during VR exposure.

Using Serious Games to Train Adaptive Emotional Regulation Strategies

Emotional Regulation ER strategies allow people to influence the emotions they feel, when they feel them, how they experience them, and how they express them in any situation. Deficiencies or deficits in ER strategies during the adolescence may become mental health problems in the future. The aim of this paper is to describe a virtual multiplatform system based on serious games that allows adolescents to train and evaluate their ER strategies. The system includes an ecological momentary assessment EMA tool, which allows the therapist to monitor the emotional status of teenagers every day in real time. Results obtained from a usability and effectiveness study about the EMA tool showed that adolescents preferred using the EMA tool than other classical instruments.

Reliability and validity of TIPS wireless ECG prototypes.

The aims of the present study are to examine the reliability and validity of the Heart Rate signal registered using two self-made wireless ECG systems, R-Tips and TipsShirt, and to compare them with another commercial ECG device typically used in psychophysiology studies. An ECG simulator was used to artificially generate signals corresponding to different cardiac frequencies. Results of the reliability study showed that the signal acquisition, signal processing and signal transmission were reliable and valid for R-Tips and TipsShirt. Consequently, these wireless ECG prototypes could be used for studies where the freedom of movements of the participants is fundamental without any loss of quality in the registered signals.

Analyzing the level of presence while navigating in a virtual environment during an fMRI scan

We have conducted an fMRI research using virtual reality to study the level of presence that subjects experience during the navigation through a virtual environment, in comparison with the presence felt during a video or a photograph viewing task. The fMRI results have not been analyzed yet, but responses to presence questionnaires have been analyzed. Presence levels are similar to those obtained while monitoring with other brain imaging techniques. The highest values are obtained for navigation tasks followed by video and photographs tasks.