Precisión del posicionamiento en interiores utilizando Bluetooth con diferentes técnicas de reconocimiento de patrones

Object indoor location is a field that receives much research effort but that is lacking enough maturity for its integration in popular devices like mobile phones. This paper describes the results of an experiment carried out to compare different pattern recognition algorithms in order to process the information from a set of Bluetooth transmitters, located in fixed positions, with the aim of locating an object in a precise position. Our conclusion is that the best algorithms, among the five we tested, are random forests and model-based clustering, which gave accuracies around 90%. We have also conducted experiments to analyse the influence of the number of Bluetooth transmitters and to determine the sets of features with better performance. The proposed approach is simple and gives 90% of accuracy for locating objects with 1 m precision, making it suitable for a wide range of applications.Facultad de Informátic

Precisión del posicionamiento en interiores utilizando Bluetooth con diferentes técnicas de reconocimiento de patrones

Object indoor location is a field that receives much research effort but that is lacking enough maturity for its integration in popular devices like mobile phones. This paper describes the results of an experiment carried out to compare different pattern recognition algorithms in order to process the information from a set of Bluetooth transmitters, located in fixed positions, with the aim of locating an object in a precise position. Our conclusion is that the best algorithms, among the five we tested, are random forests and model-based clustering, which gave accuracies around 90%. We have also conducted experiments to analyse the influence of the number of Bluetooth transmitters and to determine the sets of features with better performance. The proposed approach is simple and gives 90% of accuracy for locating objects with 1 m precision, making it suitable for a wide range of applications.Facultad de Informátic

Heart of Darkness: Heart Rate Variability on Patients with Risk of Suicide

Heart Rate Variability (HRV) is an emerging research field in the study of diverse pathologies, as long as it allows considering another measurement for detecting possible aggravations. The aim of this work is to study the applicability of the analysis of HRV in order to establish if a person is at risk of suffering from suicidal ideation. This work includes the development and testing of a heart rate acquisition and automatic analysis system, with friendly software for clinicians, customized to the necessities of an emergency unit. Furthermore, it includes the analysis of the obtained data with the purpose of assessing possible correlations between HRV parameters and personality impulsive traits. 20 patients and 10 normal cases were selected to develop this pilot study. Results show significant statistical difference (p<0.05) among patients and normal cases for pNN50, IRRR, MADRR, total HRV power, Approximate Entropy and Fractal Dimension

Detection of Heart Beat Positions in ECG Recordings: A Lead-Dependent Algorithm

This paper proposes a computerized heartbeat detection method in single-channel electrocardiograms (ECGs). First, the well-known Pan-Tompkins technique was implemented, and next, a channel-dependent version was developed, by adjusting threshold values and reducing false QRS detections. The algorithms were tested with the MIT-BIH Arrhythmia Database (original algorithm), and with the St. Petersburg Database (modified version). When validating the performances of the original Pan-Tompkins algorithm, we have achieved a sensitivity of <em>Se</em> = 99.81, at a positive predictivity (<em>P</em>⁺) = 99.85%. The F-Score was 0.9587, and the RMS RR Interval Error (RMSRRIE) resulted to be 4,480.46 ms. When analysing the performance of the modified algorithm, results provided an average value of <em>Se</em> = 99.92%, <em>P</em>⁺ = 99.98%, F-Score = 0.9718, and a mean value of 111.05 ms. for the RMSRRIE. In conclusion, the improved Pan-Tompkins algorithm provides higher values for sensitivity and positive predictivity, increased F-Score, and it significantly reduces the temporal error when estimating the positions of QRS complexes. Thus, it could be used as a starting point to detect heartbeat positions in more sophisticated computerized detection systems.\u

Effects of reclamation and regeneration processes on organic matter from estuarine soils and sediments

Three adjacent areas in the Urdaibai Estuary (NW Spain) comprising a reclaimed salt marsh, a natural salt marsh and a regenerated salt marsh were sampled in order to study edaphic processes and changes in organic matter (OM) composition related to reclamation and regeneration of soils and sediments in estuarine environments. For this, a general analytical description of the soil and sediment profiles was carried out and the OM was characterized using solid state 13C nuclear magnetic resonance (NMR) spectroscopy and analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The reclaimed salt marsh displayed very different characteristics from the natural salt marsh throughout the whole profile, indicating an important degree of change in soil quality and, particularly, in OM composition caused by the reclamation. At this reclaimed site, characterized by oxic conditions and a lack of tidal influence, transformation of the former salt marsh to grassland resulted in input of OM richer in carbohydrates and with a lower contribution of aromatic compounds than the OM in the salt marsh soils. On the other hand, the edaphic characteristics of the regenerated marsh were similar to those of the natural marsh and the vegetation cover was the same. However, the natural marsh accumulated twice the amount of organic carbon at the surface as the regenerated marsh. Furthermore, the natural marsh contained more aromatic material, as detected with NMR and the Py-GC/MS results indicated a greater presence of microbial material. These differences indicate that the regenerated marsh has not completely recovered its natural characteristics, despite the long period (more than 40 y) since the beginning of the regeneration process. We propose the composition of soil OM as a suitable long term indicator of reclamation and regeneration processes in the salt marsh environments.The research was partially financed by the Spanish Government (CN-04-245). C.S. was in receipt of an FPU grant from the Spanish Government.Peer Reviewe

Heart rate variability analysis with the R package RHRV

This book introduces readers to the basic concepts of Heart Rate Variability (HRV) and its most important analysis algorithms using a hands-on approach based on the open-source RHRV software. HRV refers to the variation over time of the intervals between consecutive heartbeats. Despite its apparent simplicity, HRV is one of the most important markers of the autonomic nervous system activity and it has been recognized as a useful predictor of several pathologies. The book discusses all the basic HRV topics, including the physiological contributions to HRV, clinical applications, HRV data acquisition, HRV data manipulation and HRV analysis using time-domain, frequency-domain, time-frequency, nonlinear and fractal techniques. Detailed examples based on real data sets are provided throughout the book to illustrate the algorithms and discuss the physiological implications of the results. Offering a comprehensive guide to analyzing beat information with RHRV, the book is intended for masters and Ph.D. students in various disciplines such as biomedical engineering, human and veterinary medicine, biology, and pharmacy, as well as researchers conducting heart rate variability analyses on both human and animal data