L. Mesin - Academia.edu (original) (raw)

Papers by L. Mesin

Electronics, 2021

There are many cases in which the separation of different sources from single channel recordings ... more There are many cases in which the separation of different sources from single channel recordings is important, for example, in fluorescence spectral overlap compensation, electrical impedance signaling, intramuscular electromyogram decomposition or in the case of spike sorting of neuron potentials from microelectrode arrays (MEA). Focusing on the latter, the problem can be faced by identifying spikes emerging from the background and clustering into different groups, indicating the activity of different neurons. Problems are found when more spikes are superimposed in overlapped waveforms. We discuss the application of Biogeography-Based Optimization (BBO) to resolve this specific problem. Our algorithm is compared with three spike-sorting methods (SpyKING Circus, Common Basis Pursuit and Klusta), showing statistically better performance (in terms of F1 score, True Positive Rate—TPR and Positive Predictive Value—PPV) in resolving overlaps in realistic, simulated data. Specifically, BB...

Ultrasound in Medicine & Biology, 2019

Pulsatility of the inferior vena cava (IVC) provides information on volume status in healthy subj... more Pulsatility of the inferior vena cava (IVC) provides information on volume status in healthy subjects and in many clinical conditions. The ultrasound (US) approach to estimating the caval index (CI) is not standardized, as it is operator dependent and vulnerable to measurement errors because of different factors, including movements of the IVC and non-uniform IVC pulsatility along its longitudinal axis. We propose and test in healthy subjects an innovative automated approach, which tracks the IVC movements registered in a B-mode US video clip and estimates the pulsatility of an entire portion of the vein rather than of a single arbitrary section. Large variations in CI estimates were observed along the longitudinal axis (in the worst case, CI ranged between 15% and 60%), indicating the importance of investigating a whole portion of the vessel.

IEEE journal of biomedical and health informatics, 2013

Diagnosis of bruxism is difficult since not all contractions of masticatory muscles during sleepi... more Diagnosis of bruxism is difficult since not all contractions of masticatory muscles during sleeping are bruxism episodes. In this paper, we propose the use of both EMG and ECG signals for the detection of sleep bruxism. Data have been acquired from 21 healthy volunteers and 21 sleep bruxers. The masseter surface EMGs were detected with bipolar concentric electrodes and the ECG with monopolar electrodes located on the clavicular regions. Recordings were made at the subjects' homes during sleeping. Bruxism episodes were automatically detected as characterized by masseter EMG amplitude greater than 10% of the maximum and heart rate increasing by more than 25% with respect to baseline within 1 s before the increase in EMG amplitude above the 10% threshold. Furthermore, the subjects were classified as bruxers and nonbruxers by a neural network. The number of bruxism episodes per night was 24.6 ± 8.4 for bruxers and 4.3 ± 4.5 for controls ( P < 0.0001). The classification error bet...

Copyright © 2013 L. Mesin et al.This is an open access article distributed under the Creative Com... more Copyright © 2013 L. Mesin et al.This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pupil is controlled by the autonomous nervous system (ANS). It shows complex movements and changes of size even in conditions of constant stimulation. The possibility of extracting information on ANS by processing data recorded during a short experiment using a low cost system for pupil investigation is studied. Moreover, the significance of nonlinear information contained in the pupillogram is investigated. We examined 13 healthy subjects in different stationary conditions, considering habitual dental occlusion (HDO) as a weak stimulation of the ANS with respect to the maintenance of the rest position (RP) of the jaw. Images of pupil captured by infrared cameras were processed to estimate position and size on each frame. From such time ser...

Medical & Biological Engineering & Computing, 2004

Spatial filters are used for increasing selectivity in surface EMG signal detection. This study i... more Spatial filters are used for increasing selectivity in surface EMG signal detection. This study investigated the importance of the description of the volume conductor for inferring conclusions on comparing filter selectivity from simulation analyses. A cylindrical multi-layer description of the volume conductor was used for the simulation analysis. Different anatomies were analyzed with this model and results on filter selectivity compared. The longitudinal single (LSD), double (LDD) and normal double differential (Laplacian, NDD) filters were investigated. Largely different conclusions could be drawn when comparing filter selectivity resulting from simulations with different volume conductor models. A filter which performed best with a particular anatomy could be the poorest with another anatomy. While with a bone/muscle model and superficial fibers, the ratio between peak-to-peak values of the propagating and non-propagating signal components was approximately 220% for LDD and LSD and lower than for NDD (approximately 290%), with a bone/muscle/fat/skin model LSD performed significantly worse (150%) than both LDD and NDD, which showed similar performance (approximately 300%). Similarly, increasing the lateral distance of the recording by 10°, signal amplitude was reduced to 2% with LSD and LDD and to 4% with NDD. With another anatomy, LSD and LDD reduced signal amplitude to 20-25% while NDD reduced it to 4%. Similar considerations could be drawn for other selectivity indexes. Thus, modeling should be used carefully to infer conclusions on spatial selectivity and to indicate particular selections of spatial filters.

The American Journal of Cardiology, 1990

To evaluate a simple noninvasive means of estimating right atrial (RA) pressure, the respiratory ... more To evaluate a simple noninvasive means of estimating right atrial (RA) pressure, the respiratory motion of the inferior vena cava (WC) was analyzed by O-dimensional echocardiography in 63 patients. Expiratory and inspiratory IVC diameters and percent collapse (caval index) were measured in subcostal views within 2 cm of the right atrium. Parameters were correlated with RA pressure by flotation catheter within 24 hours of the echocardiogram (36 were simultaneous). Correlations between RA pressure (range 0 to 28 mm Hg), expiratory and inspiratory diameters and caval index were 0.46,0.71 and 0.75, respectively. of 46 patients with caval indexes <SO%, 41 (89%) had RA pressure 110 mm Hg (mean f standard deviation, 15 f 6), while 30 of 35 patients (66%) with caval indexes ~50% had RA pressure <lO mm Hg (mean 6 f 5). Sensitivity and specificity for discrimination of RA pressure 1 or <lO mm Hg were maximized at the 50% level of collapse. Thus, IVC respiratory collapse on echocardiography is easily imaged and can be used to estimate RA pressure. A caval index 250% indicates RA pressure <lo mm Hg, and caval indexes <SO% indicate RA pressure 110 mm Hg.

Lecture Notes in Computer Science, 2010

Local air quality forecasting can be made on the basis of meteorological and air pollution time s... more Local air quality forecasting can be made on the basis of meteorological and air pollution time series. Such data contain redundant information. Partial mutual information criterion is used to select the regressors which carry the maximal non redundant information to be used to build a prediction model. An application is shown regarding the forecast of PM10 concentration with one day of advance, based on the selected features feeding an artificial neural network.

Modelling in Medicine and Biology VI, 2005

Surface electromyogram (EMG) is a bio-electrical signal detected non-invasively (over the skin) a... more Surface electromyogram (EMG) is a bio-electrical signal detected non-invasively (over the skin) and reflecting features of the bio-electrical sources associated to muscle contraction. Surface EMG signal modelling has important applications in the interpretation of experimental EMG data, for a deeper understanding of the physiological mechanisms of muscle contraction. This study addresses the issue of introducing a general analytical method to study multi layer volume conductors (i.e., to solve a Poisson problem on domains constituted by multiple layered sub-domains, with different electrical conductivities). The method provides the solution to a multi plane layer problem, once the solutions of the homogeneous Dirichlet and Neumann problems in a one layer volume conductor are available. The same method can be applied to cylindrical layer volume conductors (some indications are given). It is applied to add a fat layer over a bipinnate muscle layer (i.e., a muscle which has two groups of fibres with two orientations) which was analytically studied in the literature (considering only the muscle layer). The study provides an implementation of the results in a complete surface EMG generation model (including finite length fibres), and shows representative results of the application of the model proposed. Poisson equation models different physical and biological situations. Thus, the method introduced can find applications in other fields of interest for the applied sciences.

The 2011 International Joint Conference on Neural Networks, 2011

The issue of air quality is now a major concern for many citizens worldwide. Local air quality fo... more The issue of air quality is now a major concern for many citizens worldwide. Local air quality forecasting can be made on the basis of meteorological variables and air pollutants concentration time series. We propose an adaptive filter technique based on an artificial neural network (ANN) to make 24-hours maximal daily ozone-concentrations forecasts.

Journal of Electromyography and Kinesiology, 2009

Pupil is controlled by the activity of the autonomous system. Under constant light and visual sti... more Pupil is controlled by the activity of the autonomous system. Under constant light and visual stimulus, it performs complex size oscillations and movements. Here, it is assumed that pupil behavior can be described by some unknown nonlinear deterministic rules. The techniques of time series embedding are applied to pupil size, obtaining a trajectory in the phase space. A trajectory is also obtained considering the movements of the eye. Indexes are obtained from Fourier analysis and from recurrence quantification analysis applied to trajectories in the phase space of the time series sampling pupil size and movement. Some insight into pupil control is obtained investigating data recorded in different stationary conditions (light vs darkness, rest position of the jaw vs dental occlusion).

Biomedical Signal Processing …, 2008

Electronics

European Heart Journal - Cardiovascular Imaging

Background In clinical practice, as stated in the ASE guidelines, the echocardiographic estimatio... more Background In clinical practice, as stated in the ASE guidelines, the echocardiographic estimation of right atrial pressure (RAP) is based on the size of the inferior vena cava (IVC) and its inspiratory collapse. However, this method has proven to have limits of reliability and reproducibility. The use of a recently developed software that with a semi-automatic technique highlight the edges of the IVC could help to standardize the echocardiographic assessment of RAP. Aim of the study: The aim of the study was to assess feasibility and accuracy of a new semi-automated approach to estimate the RAP. Standard acquired echocardiographic images were processed with a semi-automatic technique, indexes related to the collapsibility of the vessel during inspiration (Caval Index, CI), during the whole respiratory cycle (Respiratory Caval Index, RCI) and through the heart cycle transmitted movements’ (Cardiac Caval Index (CCI) were derived (figure 1). Using these indexes, we developed two model...