Information coding within a population of neurons was studied by simultaneously observing their activity using extracellular recordings. It was found that the largest neurons' activity could be reliably monitored ...
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Information coding within a population of neurons was studied by simultaneously observing their activity using extracellular recordings. It was found that the largest neurons' activity could be reliably monitored and that directional information was more clearly coded by the number of action potentials (APs) that by latency. For both individual and ensemble properties of the observed cells it was found that the number of APs was more important than time to AP firing for right vs. left discrimination. The analyses showed that the large giant interneurons observed had information within their responses to discriminate wind direction-as is required if they are to orient escape turning.< >
Transesophageal atrial pacing (TAP) has been proposed as a noninvasive alternate modality of cardiac stress for patients who cannot perform an adequate exercise stress test. Present computer methods for processing the...
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Transesophageal atrial pacing (TAP) has been proposed as a noninvasive alternate modality of cardiac stress for patients who cannot perform an adequate exercise stress test. Present computer methods for processing the exercise ECG are inadequate in analyzing the unique surface ECG recorded during a TAP stress procedure. This is due to the presence of large simulator-induced pacing artifacts which confound computer beat identification. The authors have developed hardware to suppress the large pacing artifact, and a software method to detect the R wave, determine sustained capture, and calculate beat-by-beat and average ST-segment level, St slope, R-wave amplitude, and instantaneous RR interval and heart rate. They employ five different computer methods (single-point, average, weighted-average, linear least-squares and parabolic least-squares) in ST-segment measurements. They demonstrate the deficiency of present exercise ECG computer methods in processing the ECG during stress and show the significantly enhanced performance of their own technique on real ECG data.< >
An approach to the analysis of event related potentials (ERP) based on information theory is described. The amount of information in cortical potentials evoked by words briefly presented by tachistoscope is measured b...
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An approach to the analysis of event related potentials (ERP) based on information theory is described. The amount of information in cortical potentials evoked by words briefly presented by tachistoscope is measured by a transinformation method. The inputs to the communication channel are four word categories. One category is composed of pleasant words, another of unpleasant words, both drawn from the Osgood semantic differential research, and two categories are composed of word stimuli related to a psychiatric patient's complaints. The patients chosen for study exhibit either phobias or pathological grief reactions. The method allows ERP's to be mapped into transinformation profiles that reveal time intervals during the poststimulus ERP favorable to the transmission of information concerning the word category presented. The transinformation model results for actual and synthetic data are discussed.
Aerobic processes tend to show gradients in the oxygen concentration in the liquid, when performed on a large scale. In parts of the reactor productivity decreases, due to oxygen limitation. Controllers capable of mai...
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Aerobic processes tend to show gradients in the oxygen concentration in the liquid, when performed on a large scale. In parts of the reactor productivity decreases, due to oxygen limitation. Controllers capable of maintaining a sufficiently high level of oxygen throughout the entire reactor volume are necessary. Some intermediate steps in the design of such controllers are described. These controllers are tested in a pseudo full scale reactor system, consisting of two separate small scale reactors: one aerated, the other reactor stirred only, without aeration. The two compartments are interconnected by a circulation flow. Two ways of control are described, both of which function satisfactory. However, they both use information available in a well defined bench scale system, but not on a full scale. Therefore a controller has been designed, combining online parameter estimation and a Luenberger observer. This combination is the subject of present research.
作者：
OBRIEN, WDWilliam D. O'Brien
Jr. Ph.D. Associate Professor of Electrical and Computer Engineering and of Bioengineering Bioacoustics Research Laboratory Department of Electrical and Computer Engineering University of Illinois 1406 W. Green Street Urbana IL 61801.
ABSTRACT: Diagnostic ultrasound of the pulse-echo imaging type is used in at least 25 per cent of pregnancies, and Doppler continuous wave ultrasound, as employed in external electronic fetal monitors, is used in near...
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ABSTRACT: Diagnostic ultrasound of the pulse-echo imaging type is used in at least 25 per cent of pregnancies, and Doppler continuous wave ultrasound, as employed in external electronic fetal monitors, is used in nearly all pregnancies. Diagnostic ultrasound energy levels are from 0.1 to 40 mW/cm 2 . These intensity levels depend on the characteristics of the ultrasonic beam and temporal exposure. The American Institute of Ultrasound in Medicine states that…“there have been as of October, 1982 no independently confirmed significant biological effects in mammalian tissues exposed to intensities below 100 mW/cm 2 .” Some of the animal studies reviewed by the AIUM to reach this conclusion are discussed.
Certain neuronal spike trains may be viewed as stochastic, nonhomogeneous point process. Neuronal information may be encoded in the time-varying mean rate of the spike train in some cases. For this purpose the simulat...
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The paper describes the application of a swept-frequency-system identification technique to biological systems. By linearly sweeping the frequency of the sinusoidal input signal over the range of frequencies of intere...
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The paper describes the application of a swept-frequency-system identification technique to biological systems. By linearly sweeping the frequency of the sinusoidal input signal over the range of frequencies of interest, the frequency-response profile of the biological system can be rapidly determined. System transfer characteristics are extracted from the input-power spectral density and output-input crosspower spectral-density computations. Noise, harmonic distortion and sweeptime considerations are given. Logarithmic frequencysweeping is suggested as a means of avoiding harmonic distortion.
We have come to know that our ability to survive and grow as a nation to a very large degree depends upon our scientific progress. Moreover, it is not enough simply to keep abreast of the rest of the world in scientif...
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ISBN:
(数字)9781402040580
ISBN:
(纸本)9781402040573;9789048170265
We have come to know that our ability to survive and grow as a nation to a very large degree depends upon our scientific progress. Moreover, it is not enough simply to keep abreast of the rest of the world in scientific matters. 1 We must maintain our leadership. President Harry Truman spoke those words in 1950, in the aftermath of World War II and in the midst of the Cold War. Indeed, the scientific and engineering leadership of the United States and its allies in the twentieth century played key roles in the successful outcomes of both World War II and the Cold War, sparing the world the twin horrors of fascism and totalitarian communism, and fueling the economic prosperity that followed. Today, as the United States and its allies once again find themselves at war, President Truman’s words ring as true as they did a half-century ago. The goal set out in the Truman Administration of maintaining leadership in science has remained the policy of the U.S. Government to this day: Dr. John Marburger, the Director of the Office of Science and Technology (OSTP) in the Executive Office of the President made remarks to that effect during his confirmation hearings in October 2 2001.
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