A method was developed to select clinical engineering interventions which can address specific problems of quality of care in a hospital. Emphasis is placed on low cost interventions which can demonstrate the potentia...
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We present an iterative algorithm for separating the segments containing exclusively neural noise in extracellular recordings without prior knowledge of neural spike locations or waveforms. This allows on-line design ...
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We present an iterative algorithm for separating the segments containing exclusively neural noise in extracellular recordings without prior knowledge of neural spike locations or waveforms. This allows on-line design of a whitening filter and on-line determination of thresholds for detection and classification of neural spikes without human supervision. This algorithm can also be used as a first data reduction phase for the detection task.
We present a software simulation of a fully automated system that can optimally detect the occurrence, classify and resolve superpositions of neural spike waveforms from multiple neurons recorded with the same extrace...
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We present a software simulation of a fully automated system that can optimally detect the occurrence, classify and resolve superpositions of neural spike waveforms from multiple neurons recorded with the same extracellular electrode. The algorithms in this simulation are designed for on-line operation without human supervision. Therefore, the whitening filter required for optimality, waveform templates and discrimination thresholds are generated automatically.
A method was developed to select clinical engineering interventions which can address specific problems of quality of care in a hospital. Emphasis is placed on low cost interventions which can demonstrate the potentia...
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A method was developed to select clinical engineering interventions which can address specific problems of quality of care in a hospital. Emphasis is placed on low cost interventions which can demonstrate the potential of clinical engineering for developing countries. The utilization of mechanical ventilators (MV) was selected as a representative quality of care problem in a 650 bed teaching hospital. The application of the methodology developed led to the selection of an educational intervention which was shown to be effective (p
Presents a novel algorithm specifically designed for detecting clusters of microcalcifications that are early mammographic signs of breast cancer. The algorithm, which can be implemented in a general-purpose computer,...
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Presents a novel algorithm specifically designed for detecting clusters of microcalcifications that are early mammographic signs of breast cancer. The algorithm, which can be implemented in a general-purpose computer, is intended to assist the radiologist by indicating the location of suspicious clusters. A small number of parameters (features) are extracted from the mammogram and used in a decision-making process that requires no human supervision.< >
Several different types of oscillation were observed during flow through a thick-walled silicone rubber tube when the external pressure was large enough to cause collapse. The Reynolds number was above 4,400. With ups...
Several different types of oscillation were observed during flow through a thick-walled silicone rubber tube when the external pressure was large enough to cause collapse. The Reynolds number was above 4,400. With upstream head, and transmural pressure at the downstream end of the tube, as control variables, control-space diagrams exhibited well-defined regions of low (2–6 Hz), intermediate, and high frequency (over 60 Hz) oscillation, and of small noise-like fluctuations. The data, including aperiodic oscillatory operating points which may indicate the presence of chaos, are analyzed by dynamical systems methods. Transitions between different regions of control space are discussed in terms of topological bifurcation types. Spectral analysis is used to distinguish between quasi-periodic and aperiodic waveforms. Although the dimension of the dynamical system is unknown, phase planes are plotted, both as one transduced signal versus another and as one versus itself delayed. Return maps and Poincaré sections are plotted, the latter using three-dimensional phase portraits in which the third coordinate axis was produced by further delay of the one signal. Coordinates for higher-dimensional phase portraits are also defined, using the eigenvectors of covariance matrices constructed from sequences of the recorded data points for one signal. Poincaré sections are plotted for such three-dimensional portraits, using the lowest-frequency-component coordinates. Singular value decomposition of “local neighbourhood” matrices is used to define the local dimension of the system in a small region of the high-dimension phase space. Despite the use of these sophisticated techniques, one cannot unequivocally conclude from these data sets that the system is chaotic. The applicability of such methods to complex experiments that yield data which are nonoptimal for these purposes are discussed.
Aqueous flow through thick-walled silicone rubber tubes held open at both ends and externally pressurized is investigated for tubes of four different lengths, each at three levels of downstream flow resistance. The tu...
Aqueous flow through thick-walled silicone rubber tubes held open at both ends and externally pressurized is investigated for tubes of four different lengths, each at three levels of downstream flow resistance. The tubes are compared at operating points spanning all the observed types of dynamic behaviour, where an operating point is set by adjusting driving pressure head and external pressure. It is found that longer tubes display relatively more oscillatory operating points, while shorter tubes display more divergently unstable operating points. The observed self-excited oscillations can be divided into well-separated bands of low, intermediate and high frequency, within each of which the frequency generally increases gradually with flow-rate and external pressure. In addition, in the region at high external pressure where turbulent noise dominates, isolated operating points display very-high-frequency repetitive oscillations of small amplitude. The border between the noise-dominated region and the region below, independently of whether the latter is oscillatory or divergent, displays complex behaviour. This includes aberrantly high frequency oscillation which is sometimes superimposed on a particular phase of a low-frequency oscillation, and the behaviour depends on whether the external pressure has previously been higher or lower. Whereas the regions of low, intermediate and high frequency oscillations are arranged such that in general higher flow-rates and external pressures cause transitions to higher-frequency bands, these aberrant `border oscillations' yield very high frequencies at low flow-rate and external pressure. The minimum frequency of oscillation decreases in longer tubes, but the dependence is far weaker than if end-to-end wave propagation were the period-setting mechanism. Longer tubes appear predisposed to more widespread low-frequency modes, although high frequencies can be excited with sufficient flow-rate and external pressure. Few low-frequen
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