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Oxygen dissociation curves (ODC) plotted by a semi-automatic analyzer are subsequently processed by a digital computer. This computer processing provides a complete determination of the ODC, hence offering more information than the single P50 generally used. The programs consist of three successive modules each with a higher degree of sophistication in the processing. The mass handling of the curves is also described.
The largest change in spirometric pulmonary function testing in the last 10 years has been the introduction of the digital computer for data acquisition and reduction. Computer-assisted spirometry can enhance the effectiveness of spirometric testing by increasing test accuracy, increasing patient acceptance, and decreasing the time necessary to complete the test and its interpretation. Any computer-assisted spirometer should be easy to use and should clearly display and properly report test results. I recommend that the American Thoracic Society Standards for spirometric testing be used by pulmonary function laboratories and that test interpretation made by a computer be verified.
A simple programme was written in ALGOL 1204 for the Polish digital computer ODRA 1204. It permits the fitting of the biexponential equation C = Ae-alphat+Be-betat to the observed plasma or serum concentration data of a drug after a single iv injection.
A mathematical model of myelinated axon was programmed for digital computer solution of the consequences of the conduction characteristics when the model membrane was affected by local anesthetics simulated by alteration of the ionic conductance parameter. The effects of tetrodotoxin on impulse conduction were studied in detail by means of a systematic reduction in sodium conductance in 1 to 10 nodes of Ranvier. Rhis technique simulates the method used experimentally and clinically to achieve a conduction block with the circumscribed application of local anesthetics to segments of nerve axons or nerve trunks. The analysis of the tetrodotoxin "dose-response" relationships revealed the fact that the model myelinated axon could support three types of conduction when depressed by this drug. One type of conduction of a subnormal impulse at the nodes of Ranvier; a second is characterized by a form of decremental conduction in which the rate of decrement of the nodal impulse is linear with distance. The third type is a second form of decremental conduction which is exponential in configuration and is seen when the g(Na) at the nodes of Ranvier is reduced to less than 27% of normal. Parallel experiments were performed to simulate the effects of lidocaine and some significant differences were observed. Analysis of the action potentials within the internodel region suggests that, although immune to drug action in the model, the internodal segment affects the generation of action potentials at the nodes. A commentary is presented on the limitations of the model as it reflects known pharmacologic relationships in real myelinated axons.
The current project assessed the accuracy of a period-analytic computer program in the quantification of delta EEG activity during sleep for the purpose of the assignment of sleep stage. Ninety-four 25-sec epochs of data from two subjects were analyzed both using the computer and by two visual scorers in order to generate percent measures of the amount of delta in the EEG. This information was then used to assign stage score. A comparison of the inter-scorer and scorer/computer agreements showed good correspondence between them, with the human/computer contrasts being equivalent to the human/human contrasts. Data are presented for both the percent of delta in the records and for the agreement of stage score assignments. It was concluded that the computer program provided an acceptable alternative to human visual scoring. Suggestions as to how to implement digital computers in sleep research were presented.
Female Sprague-Dawley rats were divided into three groups. All three groups were given the same solid diet (with 1.6 ppm F). Group I was given deionized water, group II drank water with 5 ppm fluoride added, and group III had 50 ppm fluoride added. All females were mated with the same male. The pups were sacrificed at 28 days, and the mandibles were removed and cleaned. Three-dimensional representations of the occlusal surfaces of the 1st and 2nd mandibular molars were reproduced via computer-digitized images using stereophotogrammetry. Fissure depths and widths were measured, and 'volumes' of the fissures were computed. The fissure widths, depths, and volumes were compared statistically using unpaired t tests between groups (p less than 0.05). There were significant differences in fissure depth between groups I and II and between groups I and III. For fissure volumes, significant differences were found between groups I and III. The width of the fissure and the overall tooth size were not significantly different between fluoride-treated groups. Standardization showed a reproducibility to within +/- 40 mm with the stereophotogrammetric method.
This study evaluated the Digitizing Computer System (DCS Production) for computer-controlled fabrication of titanium copings. The three-dimensional shape of the crown preparations was acquired through micropalpation with a contact digitizer on the master cast. In this in vitro study the marginal fit of computer-machined titanium frameworks for veneered crowns was assessed using scanning electron microscopy. Measurement of the marginal gap between the framework and the tooth was performed along the entire length of the finish line. The evaluation was based on 1,475 individual measurements on 10 test specimens. The mean values of marginal fit for the individual crowns ranged from 21.2 +/- 14.6 microns to 81.6 +/- 25.1 microns. The mean value for all crowns was 47.0 +/- 31.5 microns.
Thirty consecutive patients with acture myocardial infarction had continuous magnetic tape recording of their stay in the coronary care unit. Analysis of the 24 hour tape recordings was implemented on a Honeywell model 316 digital computer. In the first 24 hours after admission to the coronary care unit, 12 of the 30 patients (40 percent) exhibited nonparoxysmal junctional tachycardia; in 5 the arrhythmia was not recognized by conventional monitoring techniques. For the subsequent 3 days, the incidence rate of the arrhythmia was 13 percent for the first 48 hours and 3 percent for 72 hours. Although the mortality rate in patients with nonparoxysmal junctional tachycardia was greater than in patients not demonstrating the arrhythmia (33 versus 6 percent), there was a greater percentage of patients with anterior infarction in the former group; therefore, mortality may have been related to site of infarction rather than being reflective of the arrhythmia or its associated pathophysiologic state. Of possible significance is the association of a greater degree of sinus arrhythmia with nonparoxysmal junctional tachycardia. The incidence of nonparoxysmal junctional tachycardia in this group of patients was greater than previously reported. It is possible that computer tape analysis may have provided more accurate recognition of the arrhythmia and, thus, more realistic incidence data. The association of nonparoxysmal junctional tachycardia with sinus arrhythmia could only have been recognized by computer technique. The computer system is not a diagnostic system but rather a tape review method.
A survey of higher types of number, with more sophisticated arithmetics than square root -1, is presented. Such powerful embodiments of the number concept are capable of representing entities and operations in the bio-sciences, where phenomena are characteristically more recondite than in naively reductionist, mechanistic physics or chemistry, which today even quantum theory (which itself deploys two kinds of hypernumber) has shown to be inadequate to explain observed phenomena. When the bio-sciences enter the picture, four other kinds of hypernumber are needed, one of them (w) relating also to the frontiers of quantum theory, in terms of the resolution of problems such as the breakdown of parity conservation and of time reversal, and the concomitant elimination of unwanted divergences (infinities). A brief statement of the relevance of each of the additional kinds of hypernumbers in bio-scientific computing is furnished, as an introduction to an approach that is not only viable in terms of digital computing, but is fraught with new implications for bio-scientific research.
A program has been developed for digital computer simulation of the movement of a flagellar model consisting of straight segments connected by joints at which bending occurs. The program finds values for the rate of bending at each joint by solving equations which balance active, viscous, and elastic bending moments at each joint. These bending rates are then used to compute the next position of the model. Stable swimming movements, similar to real flagellar movements, can be generated routinely with a 25-segment model using 16 time steps/beat cycle. These results depend on four assumptions about internal flagellar mechanisms: (a) Bending is generated by a sliding filament process. (b) The active process is controlled locally by the curvature of the flagellum. (c) Nonlinear elastic resistances stabilize the amplitude of the movement. (d) Internal viscous resistances stabilize the wavelength of the movement and explain the relatively low sensitivity of flagellar movement to changes in external viscosity.
In order to clarify the genesis of the human pressure and flow pulse contours of the distal leg arteries, in particular the posterior tibial artery, pulse recordings were performed with transcutaneous techniques under normal conditions and in the state of strong vasodilatation (reactive hyperaemia) in the distal parts of the lower legs. From the experimental results it is concluded that the contour of the incident pressure wave arriving in the leg arteries is very similar to the pressure pulse contour of the abdominal aorta, while the resulting contour in the leg arteries is determined by this incident wave and superimposed reflected waves. The latter arise from positive reflection in the periphery of the lower legs. The travel in retrograde direction, are reflected negatively in proximal regions, particularly in the abdominal aorta, and appear again, with opposite sign, in the leg arteries. In addition, retrograde waves reflected positively at the aortic valve and then traveling in antegrade direction also influence the pulse contours. By considering this wave travel, the genesis of the characteristic contours of the pressure and flow pulses of the lower leg arteries is explained in a satisfactory way. This is demonstrated by a simplified graphical pulse construction as well as by the calculation of pulse contours on the basis of a theoretical tube model of the arterial system with the aid of a digital computer. The results of these calculations are discussed with respect to the findings of previous investigators who used analog and digital models of the arterial system.
In the paper, according to theoretic reliability analysis and experiment research, the System Reliability of NXS X-ray image medical machine is studied by a new computer digital simulation method. The practical method is mainly suggested on its FTA model simulated by algorithm on a computer, then the Reliability Probability, MTBF and Structure Importance on the machine are obtained. The System Reliability results are discussed in detail finally.
Accurate measurement of pressure differences across a diseased heart valve involves either laborious planimetry or elaborate digital computing facilities. An analogue device is described, simple and inexpensive to construct, which derives from the recorder input of two pressure signals the time (seconds/minute) of valve opening and the mean pressure difference during this time. Measurements may be repeated over long periods. The importance of using pressure differences as compared with peak or end diastolic gradients is noted; serious errors in assessment of valvular disease may otherwise occur.
The movements of two kinds of molluscs (Paludina viviparus and Heliosoma (taphius) Nigricans) (in Argentina Biomphalaria tenagophila) performing feeding activities have been simulated by a digital computer. Successive positions of the organisms were determined by a computer program which was based on Rashevsky's (1973) Principle of Adequate Design.
A recent model of respiratory control suggested that the steady-state respiratory responses to CO2 and exercise may be governed by an optimal control law in the brainstem respiratory neurons. It was not certain, however, whether such complex optimization behavior could be accomplished by a realistic biological neural network. To test this hypothesis, we developed a hybrid computer-neural model in which the dynamics of the lung, brain and other tissue compartments were simulated on a digital computer. Mimicking the "controller" was a human subject who pedalled on a bicycle with varying speed (analog of ventilatory output) with a view to minimize an analog signal of the total cost of breathing (chemical and mechanical) which was computed interactively and displayed on an oscilloscope. In this manner, the visuomotor cortex served as a proxy (homolog) of the brainstem respiratory neurons in the model. Results in 4 subjects showed a linear steady-state ventilatory CO2 response to arterial PCO2 during simulated CO2 inhalation and a nearly isocapnic steady-state response during simulated exercise. Thus, neural optimization is a plausible mechanism for respiratory control during exercise and can be achieved by a neural network with cognitive computational ability without the need for an exercise stimulus.
This study was designed to pinpoint the site at which N-hexanoyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP-hex) exerts its previously reported effect on thalamic neurons in rats. The animals were prepared under chloralose-urethane anesthesia for a stereotaxic approach to either the nucleus ventralis posterolateralis (nVPL) or the centrum medianum-parafascicularis complex (CM-Pf) of the thalamus. Individual neurons in these nuclei were separately activated by single-pulse stimulation of the sciatic nerve or the thalamic fibers that form reciprocal connections between the CM-Pf and the second somatosensory (SII) region of the nVPL. Poststimulus time histograms were constructed from computer readouts of the stimulus-evoked responses of a neuron during a 500-ms period accumulated in a digital computer 100X. In addition, the number of spikes accumulated in each histogram was compared to the number of spikes accumulated under identical conditions on the same neuron after intracarotid infusion of 5-HTP-DP-hex. The effect of the drug was reversed by the infusion of 5-HTP. Statistical evaluation of the accumulated spike counts indicated that 5-HTP-DP-hex suppressed only the excitation of CM-Pf neurons from the SII of the nVPL; the input of the sciatic nerve into the CM-Pf remained unaltered. Furthermore, no effect was exerted by this dipeptide on the afferent excitation of neurons in the SII of the nVPL.(ABSTRACT TRUNCATED AT 250 WORDS)
A multiple illumination wavelength multiparameter flow cytophotometer system, using laser sources and controlled by a small, general-purpose digital computer, has been produced for use in the development of new flow cytometric techniques. Three different laser wave-lengths can be used simultaneously to illuminate different regions of the flow chamber; as many as five measurements of light scattering at various angles, extinction, and fluorescence at one or more wavelengths can be made at each illuminated station. Cells in suspension may be examined at rates of 1000 cells/sec, with seven correlated optical measurements being recorded for each cell. A library of programs for data manipulation and statistical analysis make it possible to use the system to develop and implement cell characterization, counting and classification procedures for basic and clinical research applications.
PURPOSE: A microangiographic technique is described, which allows visualization of small blood vessels with a diameter of approximately 20 microm and quantification of fasciocutaneous blood vessels by means of digital computer analysis in very small laboratory animals. METHOD: The left carotid artery of 45 nu/nu mice was cannulated (26 gauge) and a mixture of gelatine, barium sulfate and green ink was injected according to standardized protocol. Fasciocutaneous blood vessels were visualized by digital mammography and analyzed for vessel length and vessel surface area as standardized units (pixel) by computer program. RESULTS: With the described microangiography method fasciocutaneous blood vessels can be clearly visualized. Regions of interest (ROIs) can be defined and the containing vascular network quantified. Identical ROIs showed a high reproducibility for measured unit (pixel) < 6.5 +/- 2.4 %. By the use of digital image, processing the quantification of vessels was reliable, reproducible and fast. CONCLUSION: Combining microsurgical techniques, pharmacological knowledge and modern computer imaging analysis systems, we were able to visualize and quantify blood vessels with a diameter of approximately 20 microm even in small laboratory animals.