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Proceedings of the 1991 IEEE Seventeenth Annual Northeast Bioengineering Conference

4-5 April 1991

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Displaying Results 1 - 25 of 112
  • Establishing constitutive relationships for soft biological tissues

    Publication Year: 1991
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (58 KB)

    Summary form only given. An algorithm is presented by which stress-strain relationships, or constitutive equations, for various soft tissues may be developed, and some of the pitfalls affecting the process are discussed. These concepts are illustrated using the lung as an example. Four elements are required for analysis of the deformation of a body: (1) the geometry of the body in question, (2) a ... View full abstract»

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  • Detection of EEG transients by changes in dimensional complexity

    Publication Year: 1991
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (31 KB)

    Summary form only given. A simple box accounting algorithm is applied to measure the fractal dimension of electroencephalography (EEG). Artificial transients of varying EEG characteristics are embedded. The change is noted in the fractal dimension within a window that is passed along the entire time series. Three embedded evoked potential spikes 100 ms apart buried anywhere in the time series are ... View full abstract»

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  • Proceedings of the 1991 IEEE Seventeenth Annual Northeast Bioengineering Conference (Cat. No.91CH2997-5)

    Publication Year: 1991
    Request permission for commercial reuse | PDF file iconPDF (12 KB)
    Freely Available from IEEE
  • A single artery model with stenosis in the time domain

    Publication Year: 1991, Page(s):87 - 88
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (128 KB)

    A time domain model of pressure pulse propagation in a single artery with stenosis is presented. The aortic pressure pulse is used as input with a single axisymmetric stenosis of varying parameters simulated at 15 cm from the heart in the 30-cm segment of aorta modeled. Results are presented for stenosis length and percent constriction variation for two stenosis shapes (cylindrical and triangular)... View full abstract»

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  • Oscillatory flow distribution at a bifurcation

    Publication Year: 1991, Page(s):85 - 86
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (128 KB)

    Flow-distribution in a 90° bifurcated airway during high-frequency oscillation is analyzed by numerical simulation. The parent and two daughter branches are of equal length and diameter, describing a T-junction rotated by 90°. The flow is considered laminar and incompressible, which is reasonable for small tidal volumes. The solution has been limited to two-dimensional channels, merely by ... View full abstract»

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  • Sensitivity of phase III slope to FRC and breathing pattern in a single-path airway model

    Publication Year: 1991, Page(s):81 - 84
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (256 KB)

    A numerical solution of the convection-diffusion equation with an alveolar source term in a single-path model (SPM) of airway gas transport simulates steady state CO2 washout. The SPM is used to examine the effects of independent changes to adjustable model parameters of lung volume and breathing pattern on the slope of phase III of the single breath CO2 washout curve. The pa... View full abstract»

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  • A parallel implementation of a multi-state Kalman filtering algorithm to detect ECG arrhythmias

    Publication Year: 1991, Page(s):239 - 240
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (172 KB)

    Detecting arrhythmias from the electrocardiogram (ECG) is of vital importance for the continued development of an intelligent cardiovascular monitor (ICM). The ICM's main goal is to present to the clinician a high-level analysis of the patient's condition based upon low-level physiologic signals (e.g., blood pressure, heart rate, etc.). The authors report on the parallel implementation of a multi-... View full abstract»

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  • Approximate entropy: a complexity measure for biological time series data

    Publication Year: 1991, Page(s):35 - 36
    Cited by:  Papers (7)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    Difficulties with, and the possible inappropriateness of, applications of dimension and entropy algorithms to biological data, such as heart rate and electroencephalography (EEG) data, are indicated. A recently developed family of statistics, ApEn, can classify complex systems, given at least 1000 data values in diverse settings that include both deterministic chaotic and stochastic processes. The... View full abstract»

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  • Interaction of magnetic field with blood flow

    Publication Year: 1991, Page(s):79 - 80
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    A mathematical model governing steady laminar flow of an incompressible fluid subjected to a steady magnetic field including internal heating due to Joule effect, heat transfer due to conduction and convection, and thermally induced buoyancy forces has been developed. The thermal buoyancy was accounted for via Boussinesq approximation. To demonstrate effects of the Lorentz and Joule heating on the... View full abstract»

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  • Ultrasound Doppler system with swept frequency excitation

    Publication Year: 1991, Page(s):237 - 238
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (144 KB)

    A Doppler system based on frequency modulated excitation signals (FM Doppler) in the form of coherent linear sweeps is described. Both depth and velocity information can be extracted from the received signals by either of two processing schemes: phase shift measurement (PSM) and frequency (or spectral) shift measurement (FSM). The PSM is similar to the processing used in the conventional pulsed wa... View full abstract»

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  • Chaotic statistics of biomedical time series

    Publication Year: 1991, Page(s):33 - 34
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (220 KB)

    New statistical techniques are reviewed that have been developed specifically for the analysis of chaotic systems. These techniques involve new concepts that are largely unrelated to those developed for the analysis of linear systems. Three such techniques are discussed: dimension, entropy, and Lyapunov exponents. All three techniques have a common starting point: embedding the time series. It is ... View full abstract»

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  • Computational studies of blood flow in the heart in two and three dimensions

    Publication Year: 1991, Page(s):77 - 78
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    A computational model of blood flow in the heart is developed. The numerical method is based on the projection method for solving the time-dependent Navier-Stokes equations. This method has been used to study the flow of blood in both two-dimensional and three-dimensional models of the heart. The two-dimensional model has been used to study flows through the mitral valve, both natural and prosthet... View full abstract»

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  • A model of connective tissue micromechanics

    Publication Year: 1991, Page(s):20 - 21
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (148 KB)

    Unifying concepts at the level of microstructure are developed to account for macroscopic connective tissue elasticity, energy dissipation, and its time-varying response to mechanical loads. A fiber-fiber kinetics model based on the assumption that both rate-dependent and rate-independent dissipative stresses arise in the interaction among fibers in the connective tissue matrix is established. The... View full abstract»

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  • The development and initial testing of a new sensor to simultaneously measure strain and pressure in tendons and ligaments

    Publication Year: 1991
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (92 KB)

    A miniature sensor was constructed to simultaneously measure both local strain and pressure in soft tissues. An attempt was made to determine if the data output from the sensor can be used to determine the absolute zero strain reference or the Hall effect strain transducer (HEST) length at which the tendon just begins to be loaded. With this reference, an attempt was also made to determine whether... View full abstract»

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  • Control of robotic motion with neuron-like elements

    Publication Year: 1991, Page(s):28 - 29
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (168 KB)

    Using a controller made up of models of biological nerve cells, a controller network for a robotic limb was designed that incorporates pertinent environmental information into its motion directives, and does so without the need for conventional computers. Feedback information pertaining to the position, velocity, and acceleration of the robotic limb is encoded into compatible frequency-based signa... View full abstract»

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  • Use of ventilator driven forced oscillations for characterizing human respiratory mechanics at low frequencies

    Publication Year: 1991, Page(s):73 - 74
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (156 KB)

    Frequency domain and offline and online time domain techniques are compared to estimate respiratory mechanical properties using standard ventilator waveforms at low frequencies. Both methods are shown to yield consistent parameter estimates for a simple series RC model and pure sine wave input. However, they could not accurately predict frequency dependence of respiratory resistance from 0 to 1 Hz... View full abstract»

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  • Neural modeling of the DCN: cross-correlation analysis using short-duration tone-burst stimuli

    Publication Year: 1991, Page(s):211 - 212
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (200 KB)

    A computer model of an isofrequency patch of the dorsal cochlear nucleus (DCN) was created to explore possible mechanisms for various stimulus-dependent features observed in the cross-correlations of spike trains from type-II-type-IV unit pairs. Consistent with the functional inhibitory type-II-type-IV interaction, model I-cells provide inhibitory input to model P-cells. Simulated short-duration B... View full abstract»

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  • Measuring back muscle activity in the workplace

    Publication Year: 1991, Page(s):151 - 153
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (172 KB)

    An integrated hardware/software package has been developed to measure back muscle activity in the workplace. It is a portable system that can be worn without affecting normal daily activities. The data collected in the field can be represented by a graphical output. The method can provide an objective statement about wearer's back muscle activity View full abstract»

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  • Pulmonary input impedance spectra in models of chronically altered pulmonary hemodynamics

    Publication Year: 1991, Page(s):187 - 188
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (128 KB)

    Pulmonary input impedance spectra were estimated in one-month-old lambs whose circulation had been altered during the first few days of life to mimic the pulmonary. hemodynamic states observed in infants and children with left-to-right shunts (high flow) and /or pulmonary vascular obstructive disease (high pressure). Spectral results obtained from the animal models were compared with those obtaine... View full abstract»

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  • Evolution of myocardial constitutive relations

    Publication Year: 1991, Page(s):18 - 19
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (188 KB)

    Major developments in the assessment of myocardial constitutive relations are outlined as they illustrate the progressive sophistication in experimental soft tissue mechanics. An evolution in the determination of constitutive relations is described that includes a variety of experimental techniques and different approaches to data analysis. Three approaches to the determination of a specific funct... View full abstract»

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  • Mechanism of the voltage-induced conductance change in the Na channel

    Publication Year: 1991, Page(s):169 - 174
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    A mechanism proposed for the voltage-dependent sodium channel postulates solid-state Na+ conduction through the polypeptide structure. Ion conduction is assumed to be state solid-state, through the protein subunits of the channel, rather than aqueous, through a hypothetical pore. The channel conformational change is taken to be a phase transition, with the closed state ferroelectric and... View full abstract»

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  • Structural stability prediction for thermoplastic ankle-foot orthoses

    Publication Year: 1991, Page(s):231 - 232
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (144 KB)

    A thermoplastic ankle-foot orthosis (AFO) is an orthotic appliance which extends from the calf to the foot. The solid ankle AFO (SAAFO) is used to provide forces and moments to correctly position the lower leg and foot so that more normal stance is achieved. The SAAFO is a thin shell structure, usually 3/32 to 3/16 in. thick, thermally vacuum formed to a cast representing the patient's lower leg, ... View full abstract»

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  • A solid, locked intramedullary nail, for humeral fracture fixation: a biomechanical analysis

    Publication Year: 1991, Page(s):26 - 27
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    Orthofix, a new solid interlocking intramedullary fracture fixation system, was biomechanically tested in human cadaveric humeri. The interlocking solid nail provides rigid fixation, while the targeting device lessens the need for dynamic intraoperative X-rays. Cadaveric humeri with midshaft, transverse fractures were fixed with either the Orthofix device or Broad dynamic compression plates (DCPs)... View full abstract»

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  • A comparison of 2D and 3D techniques for the determination of normal pediatric running kinematics

    Publication Year: 1991, Page(s):279 - 280
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    Two methods used for the computation of joint rotation angles associated with running are compared. The first is a full 3-D technique which allows for the determination of up to three axial rotations at each lower limb segment joint. This method is used as the basis for comparison with a relatively straightforward 2-D computational alternative. In this way, the validity of the 2-D approaches typic... View full abstract»

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  • Modelling O2 and CO2 dissociation curves of newborn infants

    Publication Year: 1991, Page(s):71 - 72
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (160 KB)

    In order to study gas exchange and respiratory control system stability in the newborn period, a model of the O2 and CO2 dissociation curves is developed which incorporates the changes in hemoglobin with age. The model is a modification of Grodin's equations. The dissociation curves generated by the computer model take into account hematocrit, bicarbonate concentration, pH, b... View full abstract»

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