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Perturbations during human gait such as a trip or a slip can result in a fall, especially among frail populations such as the elderly. In order to recover from a trip or a stumble during gait, humans perform different types of recovery strategies. It is very useful to uncover the mechanisms of the recovery to improve training methods for populations at risk of falling. Moreover, human recovery strategies...
Deep brain stimulation (DBS) has been demonstrated to effectively improve the motor symptoms of Parkinson's disease. However, the underlying mechanisms are not known. It has been reported that a period of time is required before the full effect on motor symptoms is realized after DBS is initiated and that suppression of symptoms persists after DBS ends under parkinsonian conditions. A computational...
A recent functional model of the left ventricle characterizes the ventricle's contractile state with parameters, rather than variables. The ventricle is treated as a pressure generator that is time and volume dependent. The heart's complex dynamics develop from a single equation based on the formation and relaxation of crossbridge bonds within underlying heart muscle. This equation permits the calculation...
Arterial wave speed estimated invasively from pressure (P) and velocity (U) measurements using the P-U loop method, or non-invasively from diameter (D) and U measurements using the lnD-U loop method, assume that during early systole 1) backward-running waves are absent and 2) wave speed is constant. These assumptions also form the basis of a method for correcting time lags between P (or lnD) and U...
Thermal infrared imaging (TIRI) employs a focal plane array (FPA) of infrared detectors, with associated optics and optoelectronics to remotely detect and topographically map thermal emittance. Thermal and optical properties of human physioanatomy are not fully understood yet confounding diagnostic interpretation of human TIRI's. Elucidation of the specific physical mechanism via which thermal emission...
In this paper, we propose the use of black box models for the system identification of the cardiopulmonary baroreflex control of arterial resistance and of ventricular contractility and of arterial baroreflex control of heart rate (HR) from invasive, continuous measurements of arterial blood pressure (ABP) and central venous pressure (CVP), and non invasive, continuous recordings of ECG and respiration...
In this paper, we present a neuromuscular elbow model with both motor unit pool recruitment and Hill-based contraction dynamics. The model builds upon various models reported in the literature and provides a way to quantify force and movement variability in both isometric and non-isometric contractions. The model's accuracy in estimating muscle force variability at low force levels (at less than 20%...
Parkinson's disease (PD) automatic identification has been actively pursued over several works in the literature. In this paper, we deal with this problem by applying evolutionary-based techniques in order to find the subset of features that maximize the accuracy of the Optimum-Path Forest (OPF) classifier. The reason for the choice of this classifier relies on its fast training phase, given that...
Wearable inertial systems have recently been used to track human movement in and outside of the laboratory. Continuous monitoring of human movement can provide valuable information relevant to individual's level of physical activity and functional ability. Traditionally, orientation has been calculated by integrating the angular velocity from gyroscopes. However, a small drift in the measured velocity...
A novel device, which looks like a mug, has been proposed for measuring the impedance of human hand. The device is designed to have convenient size and light weight similar to an ordinary coffee mug. It contains a 2-axis inertia sensor to monitor vibration and a small motor to carry an eccentric mass (m=100gr, r=2cm, rpm=600). The centrifugal force due to the rotating mass applies a dynamic force...
This paper reports an approach to the physical design of the coils used in a dual inductive link to provide two-way wireless communication and power for a neural recording system. The design approach makes use of an analytic model of the link performance in terms of the physical parameters of the link, which allows physical parameters to be iterated on a computer rather than on the bench to find the...
Algebraic Reconstruction Technique (ART) is a widely employed method in computed tomography since it has certain advantages, such as allowing reconstruction of data with missing projections in some angle ranges, over other techniques such as Filtered Back Projection (FBP). Recently, a regularisation technique for ART, RegART, was introduced which provides greatly reduced noise levels. However, a serious...
This paper presents a statistical image modeling approach based on Markov random field to synthesize cervical tissue second harmonic generation (SHG) images. Binary images representing fiber and pore areas of the cervix tissue are first obtained from SHG images using an image processing pipeline consisting of noise removal, contrast enhancement and optimal thresholding. These binary images are modeled...
For many emerging neural prosthesis designs that are powered by inductive coupling, their small physical size requires large current in the extracorporeal transmitter coil, and the Class-E power amplifier topology is often used for the transmitter design. Tuning of Class-E circuits for efficient operation is difficult and a self-tuned circuit can facilitate the tuning. The coil current is sensed and...
A theoretical investigation into the behaviour of the Non-Markov Parameter is performed from a signal processing perspective in contrast to previous methodologies based on stochastic processes theory. The results indicate that the NMP can be regarded as an informational metric which is indicative of the degree of low frequency synchronisation in a complex system. These results have deep implications...
A cardiac sino-atrial tissue model based on a simplified 2D disc geometry and a generic ionic model is described and optimized to fit intact-tissue microelectrode experimental recordings. Concentric regions were defined representing the central and peripheral sino-atrial node and the atrium, each with a unique set of ionic model parameters. Intracellular action potentials were recorded from the respective...
This article compares two techniques for estimating the parameters describing the motion of a phantom designed to investigate shaking baby syndrome. Parameters of a simple computational model and an impulse response function for a linear second order system were both fitted using kinematic measurements of the motion of an inverted jointed pendulum. From the two methods respectively, the rotational...
Finite element models of helical electrodes were utilized in conjunction with nerve fiber models to determine the efficacy of various changes in helical electrode design in improving nerve fiber recruitment. It was determined that an increase in the helical overlap angle does not facilitate recruitment of smaller diameter nerve fibers. The simulations led to some strategies that could potentially...
Analysis of exhaled trace gases is a novel methodology for gaining continuous and non-invasive information on the clinical state of an individual. This paper serves to explore some potential applications of breath gas analysis in anesthesia, describing a monitoring scheme for target site concentrations and cardiac output via physiological modeling and real-time breath profiles of the anesthetic agent...
In this study, we propose the use of the bubble cloud ellipsoid volume as the quantitative evaluation parameter to monitor the ultrasonic cavitation yield. The bubble cloud ellipsoid volume was calculated by using the bubble cloud image and attenuation characteristics in bubble cloud. The usefulness of this parameter was verified by observing the change in the bubble cloud under various conditions...
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