1,721,213 research outputs found
Wearable Kinaesthetic Systems for Capturing Body Posture and Gesture
No full textThis work deals with the design, the development and the evaluation of a set of sensing garments for human posture and gesture classification, from the characterization of innovative elastic and piezo-resistive textile-based sensors to the methodologies employed to gather information on the posture and movement from raw sensor data. The presented prototypes have been realized trough the integration of conductive elastomer (CE) sensors into textile substrates. CE materials show piezo-resistive properties: a fabric deformation can be related to a sensor electrical resistance variation. The basic concept of the proposed technology is that having a redundant distribution of sensors around the joints to be monitored, it is possible to associate the sensor status to parameters related to user movements. The methodology to address several technical issues, intrinsically related to the new developed technology, is reported. Data deriving from the prototypes are analyzed and compared with16those of "standard" movement tracking systems. The realized kinaesthetic garments have shown very promising performance in terms of posture reconstruction and gesture classification
Modelling whole heart electrical activity for ischemia and cardiac pacing simulation
No full textWe developed a finite element model of the electrical activity of the whole heart embedded in the torso that is proposed as an useful tool to simulate myocardial ischemia and cardiac pacing. The electrical activity of the cardiac tissue is reproduced with a bidomain model incorporated with the FitzHugh-Nagumo equations. The finite element model is developed in Comsol Multiphysics, both in two and in three dimensions. Myocardial ischemia and bradycardia can be easily simulated by simple changes to the parameters of the model. We simulated apical, anterior and posterior ischemias and the relative electrocardiographic signals. The model was exported in Simulink environment to develop a closed-loop model of cardiac pacing. We chose a demand inhibited pacemaker, which stimulates the myocardium only if the intrinsic activity of the heart is not revealed, but every type of pacemaker can be simulated. The model generates a controlled spontaneous activation in the sinoatrial node and it is also able to reproduce realistic electrocardiographic signals and the effects that the stimulation and the pathological conditions has on them
A Sensorized Garment Controlled Virtual Robotic Wheelchair
No full textThis paper presents the design and performance of a body-machine-interface (BoMI) system, where a user controls a robotic 3D virtual wheelchair with the signals derived from his/her shoulder and elbow movements. BoMI promotes the perspective that system users should no longer be operators of the engineering design but should be an embedded part of the functional design. This BoMI system has real-time controllability of robotic devices based on user-specific dynamic body response signatures in high-density 52-channel sensor shirt. The BoMI system not only gives access to the user’s body signals, but also translates these signals from user’s body to the virtual reality device-control space. We have explored the efficiency of this BoMI system in a semi-cylinderic 3D virtual reality system. Experimental studies are conducted to demonstrate, how this transformation of human body signals of multiple degrees of freedom, controls a robotic wheelchair navigation task in a 3D virtual reality environment. We have also presented how ma- chine learning can enhance the interface to adapt towards the degree of freedoms of human body by correcting the errors performed by the user
A transmurally heterogeneous model of the ventricular tissue and its application for simulation of Brugada Syndrome
No full textWe present a transmurally heterogeneous phenomenological model of ventricular tissue that is designed to reproduce the most important features of action potential propagation of endocardial, midmyocardial, and epicardial tissue. Our model consists of only 3 variables and 20 parameters. Therefore, it is highly computational efficient and easy to fit to experimental data. We exploited our myocyte model to simulate action potential propagation in a 3D slab of cardiac tissue both in healthy conditions and in presence of Brugada syndrome. The results show that our model can accurately reproduce the transmural heterogeneity of the ventricular wall and the main characteristics of electrocardiographic pattern both in healthy and pathological conditions
Diffuse fibrosis and repolarization disorders explain ventricular arrhythmias in Brugada syndrome: a computational study
Full text linkIn this work, we reported a computational study to quantitatively determine the individual contributions of three candidate arrhythmic factors associated with Brugada Syndrome. In particular, we focused our analysis on the role of structural abnormalities, dispersion of repolarization, and size of the diseased region. We developed a human phenomenological model capable of replicating the action potential characteristics both in Brugada Syndrome and in healthy conditions. Inspired by physiological observations, we employed the phenomenological model in a 2D geometry resembling the pathological RVOT coupled with healthy epicardial tissue. We assessed the insurgence of sustained reentry as a function of electrophysiological and structural abnormalities. Our computational study indicates that both structural and repolarization abnormalities are essential to induce sustained reentry. Furthermore, our results suggest that neither dispersion of repolarization nor structural abnormalities are sufficient on their own to induce sustained reentry. It should be noted how our study seems to explain an arrhythmic mechanism that unifies the classic repolarization and depolarization hypotheses of the pathophysiology of the Brugada Syndrome. Finally, we believe that this work may offer a new perspective on the computational and clinical investigation of Brugada Syndrome and its arrhythmic behaviour
Computational Efficient Model for Human Ventricular Epicardial Cells
No full textWe developed a new phenomenological model for ventricular epicardial cells. The proposed model is based on the Rogers-McCulloch formulation of the FitzHugh- Nagumo equations and consists of only three state variables. Furthermore, our model includes a simplification parameter rγ which allows increasing time and space integration by a factor equal to rγ. Our three-variable model can reproduce the main tissue-level characteristics of epicardial cells, such as action potential amplitudes and shapes, upstroke velocities, and action potential duration and conduction velocity restitution curves. Except for a reduced upstroke velocity, the simplification included in the model does not significantly affect action potential characteristics and restitution properties. In a 2D sheet, integral characteristics of reentry dynamics, such as dominant period, are only slightly influenced by the simplification. However, the trajectory of the spiral tip changes for different values of rγ
Special Issue on “Wearable Technologies”
Full text linkWearable technology will revolutionize our lives in the years to come. The current trend is to augment ordinary body-worn objects—e.g., watches, glasses, bracelets, and clothing—with advanced information and communication technologies (ICT) such as sensors, electronics, software, connectivity and power sources. These wearable devices can monitor and assist the user in the management of his/her daily life with applications that may range from activity tracking, sport and wellness, mobile games, environmental monitoring, up to eHealth.
The present Special Issue reports the recent advances in the multidisciplinary field of wearable technologies and the important gaps that still remain in order to obtain a massive diffusion.
In the frame of wearable technologies, this Special Issue of Technologies includes a total of 10 papers, including one review paper and nine research articles. Articles in this Special Issue address topics that include: wearable sensing and bio-sensing technologies, smart textiles, smart materials, wearable microsystems, low-power and embedded circuits for data acquisition and processing and data transmission
A computationally efficient dynamic model of human epicardial tissue
Full text linkWe present a new phenomenological model of human ventricular epicardial cells and we test its reentry dynamics. The model is derived from the Rogers-McCulloch formulation of the FitzHugh-Nagumo equations and represents the total ionic current divided into three contributions corresponding to the excitatory, recovery and transient outward currents. Our model reproduces the main characteristics of human epicardial tissue, including action potential amplitude and morphology, upstroke velocity, and action potential duration and conduction velocity restitution curves. The reentry dynamics is stable, and the dominant period is about 270 ms, which is comparable to clinical values. The proposed model is the first phenomenological model able to accurately resemble human experimental data by using only 3 state variables and 17 parameters. Indeed, it is more computationally efficient than existing models (i.e., almost two times faster than the minimal ventricular model). Beyond the computational efficiency, the low number of parameters facilitates the process of fitting the model to the experimental data
Heart Closed-Loop Model for the Assessment of Cardiac Pacing
No full textWe developed a closed-loop model of cardiac stimulation using a finite element model of the whole-heart embedded in the torso that is proposed as an useful tool for pacemaker design and testing. The electrical activity of the cardiac tissue is reproduced with a bidomain model incorporated with the FitzHugh-Nagumo equations. The finite element model is developed in Comsol Multiphysics, both in two and in three dimensions and then exported in Simulink environment where the pacemaker algorithm is implemented. To validate the model, we chose a demand inhibited pacemaker, which stimulates the myocardium only if the intrinsic activity of the heart is not revealed, but every type of pacemaker can be simulated. The model generates a controlled spontaneous activation in the sinoatrial node and it is also able to reproduce realistic electrocardiographic signals and the effects that the stimulation has on them
Has music a specific effect on temporal control of movements? An auditory-motor task of synchronization.
No full textThe timing of action is analyzed by studying a repetitive task in which participants are required to execute simple isochronous repetitive movements (IRMs) avoiding prerequisites for explicit temporal representation. Movements are performed in free condition and accompanying predictable time-based auditory stimuli such as metronome clicks and robustly timed musical excerpts
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