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Unobtrusive sleep monitoring allows older adults to have continuous monitoring during the night in their own homes. We propose a method to reliably estimate respiratory rate using a bed-based pressure sensor array. Movements are detected prior to respiratory rate estimation and suppressed. The amount of movement during an estimate and a weighting for the estimate are used to create a reliability metric...
The efficiency of glucose and insulin control on glucose production (EGP) plays an important role in glucose homeostasis and its derangement in diabetes. Therefore the ability to accurately quantify indices of the individual role of glucose (GEL) and insulin (SIL) in the suppression of EGP would allow to improve the understanding of liver metabolism. Measuring these indices by minimal modelling of...
Near-infrared spectroscopy (NIRS) is a useful technique for noninvasive measurement of muscle oxygenation. However, analyses of the dynamic changes in muscle metabolism based only on experimental observations of NIRS are difficult. Therefore, we constructed a mathematical model of muscle metabolism, comprising of the ATP synthesizing systems and O2 diffusion system, to identify the mechanisms responsible...
In the study of biological systems, it is often desirable to study the relationship between two simultaneously recorded signals and investigate whether one signal is causing the other. Correlation between signals can be revealed by spectral analysis techniques such as coherence. While coherence reveals the interaction strength between two signals, it does not provide directional information about...
Monitoring a range of physiological parameters in SCI patients during extended periods of daily activity and during therapy in rehabilitation raises a no of practical issues. A totally portable system with sensors and data logger can provide a clinically useful monitoring system for SCI to study the behaviour of physiological parameters during rehabilitation allows it to be prescribed and optimised...
It is estimated that over 200 million people worldwide have osteoporosis. The prevalence of osteoporosis is continuing to escalate with the increasingly elderly population. The major complication of osteoporosis is an increase in fragility fractures leading to morbidity, mortality, and decreased quality of life. This investigation aimed at profiling the incidence and risk of osteoporosis in adult...
The auditory steady-state responses (ASSR) elicited by click stimuli can be utilized for hearing screening as is traditionally done with click-evoked auditory brainstem responses (ABR). In a typical ASSR or ABR hearing screening, several recordings at different intensities are required to find the response threshold. In this study the use of binaural click stimulus with time ramping intensity produces...
Autofocusing is a fundamental procedure towards automated microscopic evaluation of blood smear and pap smear samples for clinical diagnosis. This paper presents comparison results of 16 focus algorithms based on a total of 8000 bright-field images from 10 blood smear and pap smear samples. A ranking methodology adapted from our previously proposed ranking system is used for thoroughly evaluating...
In the framework of cardiac pacing, measured chronaxies are different for current and for voltage pulses. They increase with the distance between the pacing cathode and the myocardium, and with the size of the electrode. Mathematical formulae that relate the time constants (and the chronaxies) of the strength duration curves with the parameters of the system composed by the electrode, the volume conductor...
Spatiotemporal parameters of gastric electrical control activity such as its amplitude, direction and propagation velocity are physiological parameters of distinctive clinical interest due to their potential use for differentiating between the healthy and diseased states of the human stomach. Whereas their time evolution is relatively well behaved in the case of healthy subjects, significant deviations...
The water content of stratum corneum (SC) has been reported to vary depending on the anatomical sites. Each anatomical site respectively have their own proper water content of SC which reflects the status of skin health. Also, this anatomical region can be divided into relatively wet and dry area according to the degree of the water content of SC. In this study, we tried to investigate time series...
This paper deals with the extraction of the coronary network on dynamic volume sequences, acquired in multi-slice spiral computed tomography (MSCT). The proposed approach makes use of a tracking algorithm of the vascular structure, combining a 3D geometric moment operator with a multiscale Hessian filter to estimate the vessel central axis location, its local diameter and orientation. The method performs...
We introduce a blind identification technique to reconstruct the clinically more relevant central aortic pressure waveform from multiple less invasively measured peripheral arterial pressure waveforms. We conducted initial testing of the technique in two swine in which peripheral arterial pressure waveforms from the femoral and radial arteries and reference central aortic pressure were simultaneously...
The EnSitetrade intracavitary probe system developed by Endocardial Solutions, Inc (St. Jude Medical, St. Paul, MN) was used to simultaneously record geometric information, probe potentials, and selected endocardial potentials within the right atria for four patients. Tikhonov regularization was then used to estimate endocardial potentials from probe measurements for each patient at each endocardial...
Catheter-based epicardial mapping is possible with two access methods: transthoracic access and transvenous access. Transthoracic access requires lengthy sequential mapping procedures and stable arrhythmias. Transvenous access uses the multielectrode (4-to-20 electrodes) catheters placed in the coronary veins, however, leaves most of the epicardium inaccessible to direct measurement. The aim of this...
On theoretical grounds, interstitial current injected and removed using electrodes in close proximity does not cross the membrane, while equilibration of intracellular and interstitial potentials occurs distant from electrodes widely separated. Multisite interstitial stimulation should therefore give rise to interstitial potential differences recorded centrally that depend on intracellular and interstitial...
The dynamic profile of multi parameters of electroencephalogram (EEG) pathology associated with middle cerebral ischemia occlusion in a rat model were measured. Both pronounced increase in delta activity and decrease in theta activity during ischemic injuries were observed accompanied with decrease in the complexity of EEG. Different characteristic dynamic profiles might imply different mechanism...
Patients post stroke showed substantial changes in biomechanical properties of the ankle and knee joints. However, it is not clear what the underlying mechanisms are in the hypertonic calf muscles in stroke survivors. Biomechanical properties of the medial gastrocnemius muscle in both stroke survivors and healthy subjects were investigated in vivo and noninvasively. A programmable electrical stimulator...
We present a forward problem formulation for computing biopotentials measured with dry or capacitive electrodes. This formulation is not quasistatic and has mixed boundary conditions. Our results show that simple approximations to the measurements based on capacitive coupling are adequate in most situations. We study the range of validity and errors committed in the EEG forward and inverse problems...
Arteries are viscoelastic materials. Viscoelastic laws are fully characterized by measuring a complex modulus. Arterial mechanics can be described using stress-strain dynamic measurements applied to the particular cylindrical geometry. Most materials show an energy loss per cycle that increases steadily with frequency. By contrast, the frequency modulus response in arteries presents a frequency independence...
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