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At least 541 records · Page 30Linked to original sources
PubMed1992

Microcomputer-based monitoring of cardiovascular functions in simulated microgravity.

A microcomputer-based system for non-invasive monitoring of cardiovascular system in simulated microgravity is described. The system evaluates automatically, accurately and interactively heart beat intervals, beat-to-beat non-invasive finger arterial blood pressure (systolic, diastolic, mean and pulse pressure) using a Finapres device and beat-to-beat changes of thoracic blood volume using impedance changes. In addition, beat-to-beat evaluation of cardiac mechanical function including left ventricular ejection time, diastolic time, systolic time intervals, left ventricular ejection fraction estimate and several other contractility parameters, left ventricular volume, stroke volume and cardiac output estimates are performed with high degree of automaticity.

Blood Pressure↗
PubMedDate not supplied

Microcomputer analysis of cortical power spectrum: calibration and correlates of behavioral artifacts.

Cortical power spectrum (CPS) is a quantitative estimate of EEG spectral power density. The CPS provides suitably precise data for quantification and statistical inference compared to the qualitative evaluation of EGG when interpreted by clinicians or researchers. In the past decade, the CPS has been applied to the studies of cognitive functions, memory, psi phenomena, speech laterality, and states of consciousness including coma, sleep, anesthesia, pathophysiology and pain state. However, few systematic evaluations of CPS methodology have been reported, rendering cross-laboratory comparisons difficult and external validity of experimental results uncertain. This report first describes a calibration procedure employing a microcomputer system for measuring the functional relationship between input signals and output cortical powers. Second, we examine controlled behavioral artifact effects on the CPS. The behavioral artifacts observed in the CPS can provide a measurement anchor for less ambiguous interpretation of CPS experiments conducted in clinical or laboratory settings.

Cerebral Cortex↗
PubMed1989

An IBM-PC and Commodore 64 microcomputer-based system for elicitation and recording of eyeblink reflexes.

The eyeblink reflex is well suited for the study of habituation, sensitization, reflex modification and classical conditioning in humans. A microcomputer-based system for elicitation and recording of the eyeblink reflex is described. The system consists of three functional units: (1) an air-pressure bottle and pressure-reducing valves for delivery of air puffs to the eye in order to elicit the eyeblink reflex, and a CBM 64 computer for presentations of auditory stimuli in conjunction with air puffs; (2) a pair of light-emitting diodes and photocells placed in a pair of goggles placed on the subject for detection of eyeblinks; (3) an IBM-compatible personal computer, equipped with the ASYSTANT + software for eyeblink data acquisition and overall control of experiment and parameters. The system is presently in use in our laboratory, and technical details about the system can be obtained by writing to the first author.

Acoustic Stimulation↗
PubMed1983

A microcomputer controlled system for monitoring multiple voltammetric electrodes in vivo.

An inexpensive multielectrode voltammetry system designed for in vivo neurochemical studies of the awake, unanesthetized primate has been developed. Consisting of an Apple II Plus microcomputer, parallel operational amplifier circuitry for six working electrodes, and commercially available interface boards, the system has the flexibility to implement many standard voltammetric procedures under total software control. Multielectrode monitoring is accomplished essentially simultaneously, and all channels are equipped with independent gain controls allowing for rapid amplification adjustment. An interactive chronoamperometry program, capable of making rapid 12 bit analog to digital conversions for each working electrode over four software selectable ranges, is described and system performance is evaluated.

Animals↗
PubMed1984

Hippocampal field potential: a microcomputer aided comparison of amplitude and integral.

A microcomputer based system is described for the analysis of various aspects of hippocampal field potential response recorded in vitro, either in the dendritic or somatic region. A comparison is made between the average amplitude and the time integral of synaptically evoked population spike at the cell body layer, following various intensities of stimuli delivered to the stratum radiatum. There was a good correlation between the two measures at low and intermediate intensities of stimulation. With stimulus intensities beyond those eliciting the population spike of maximal integral, the amplitude of the population spike further increased while its duration decreased. It is concluded that the integral provides a more accurate estimate of the extent of neuronal firing than the amplitude.

Animals↗
PubMed1988

A microcomputer-based sleep system: data acquisition and system calibration programs.

A data acquisition program is described for the Apple II series of microcomputers that allows for continuous, direct monitoring of electrographic elements from cortical, hippocampal and muscle leads from rats. The program detects cortical delta waves and sigma activity, hippocampal theta activity and electromyographic activity. The detected elements are counted and stored in memory at 15 second intervals (bins). Every three hours, the data are transferred to disks for permanent storage and off-line analysis.

Animals↗
PubMed1988

A microcomputer-based system for automated EEG collection and scoring of behavioral state in cats.

A data acquisition and analysis system based on an Apple II microcomputer has been developed for use in sleep studies in the adult cat. The system reliably counts delta, spindle, and EMG waveforms, PGO waves, and REMs using amplitude and frequency criteria. These data can be used to algorithmically score sleep-wake state with high reliability (greater than 90% agreement with manual scoring). This method allows for automatic and quantitative analysis of selected EEG waveforms and sleep-wake states with less expense, more time savings, and greater convenience than manual scoring.

Animals↗
PubMed1991

Time course of rat sleep variables assessed by a microcomputer-generated data base.

A microcomputer-based system is described that detects, counts and stores cortical delta and sigma waves, hippocampal theta waves and electromyographic activities in the rat by building matrices with the incidence of those four variables (columns) in 15-second bins (rows). Data tables are submitted to statistical, graphics and spread-sheet software to assess internal organization of sleep episodes and 24-hour distribution of sleep variables. Within sleep episodes, cross-correlograms reveal a delta-sigma-theta sequence, while autocorrelograms quantify clustering and periodicity of variables. Sleep accumulates in the lights-on phase, with high concentration of delta at the beginning of this sleep-predominant phase and of sigma and theta in its second half. These are notable similarities with human sleep architecture. Simple procedures for data reduction into standard behavioral state diagnosis are demonstrated. The low cost of personal computers and data acquisition interfaces facilitates the automation of complex paradigms by ad hoc on-line programs that produce as output a data base that can be processed by standard software, providing a fluid pathway of automated acquisition, analysis and presentation of data.

Animals↗
PubMed1986

Plasmid map: a microcomputer program for display and storage of plasmid data.

We describe a plasmid map program which runs on an IBM PC microcomputer and facilitates the drawing of circular plasmid maps. The user enters information from the keyboard in the form of restriction enzyme sites, genes and their locations, and other plasmid markers such as promoters, origins, or other sites. This information can then be stored in a file for future reference. The plasmid map can be displayed on the screen, printed on a dot-matrix printer, or plotted on a Hewlett Packard HP7475A plotter.

Base Sequence↗
PubMed1987

Plotting genetic maps on a microcomputer.

Maps of genetic linkage and restriction enzyme cleavage sites can be quickly prepared on an IBM PC microcomputer with the commercially available program Lotus 1-2-3. Data can be entered on the keyboard or imported from other programs. The maps can be displayed on the screen or with a printer or plotter. These procedures should be useful in the research laboratory, in preparing figures for publication and in teaching.

Chromosome Mapping↗
PubMed1988

CLUSTAL: a package for performing multiple sequence alignment on a microcomputer.

An approach for performing multiple alignments of large numbers of amino acid or nucleotide sequences is described. The method is based on first deriving a phylogenetic tree from a matrix of all pairwise sequence similarity scores, obtained using a fast pairwise alignment algorithm. Then the multiple alignment is achieved from a series of pairwise alignments of clusters of sequences, following the order of branching in the tree. The method is sufficiently fast and economical with memory to be easily implemented on a microcomputer, and yet the results obtained are comparable to those from packages requiring mainframe computer facilities.

Algorithms↗
PubMed1988

CLONING: a microcomputer program for cloning simulations.

A comprehensive computational tool is presented that performs cloning simulations using IBM PC/XT/AT or compatible microcomputers. The CLONING program contains a specific data base for restriction sites, gene markers, fragment sources and reference comments. It draws complete linear or circular maps either on the screen or employing conventional dot-matrix printers. The design of new recombinant molecules is a totally interactive process.

Cloning, Molecular↗
PubMed1989

Microcomputer-controlled administration of vasodilators following cardiac surgery: technical considerations.

Hypertension in the early postoperative period after cardiopulmonary bypass is associated with increased morbidity, and is commonly managed by the infusion of short-acting vasodilators. Automatic arterial blood pressure control by closed-loop infusion has been shown to be superior to manual control in several studies. The investigators have developed a closed-loop arterial pressure control system based on the Atari 1040ST microcomputer (Atari, Sunnyvale, CA). The program uses a proportional-integral-derivative control algorithm, developed from that described by Sheppard and his colleagues. The arterial waveform is sampled digitally, and the waveform analysis routine incorporates several artifact detection and rejection functions. Additional safety features are provided in the computer-infusion pump subroutine, which cause alarms to be activated if computer-pump communication fails to occur within a specified time period. A novel feature of this system is the clinical staff's use of a "mouse" to enter data and control the program, which makes keyboard skills unnecessary. This system is in routine service in the cardiac intensive care unit (CICU), both for direct clinical use and for research into various aspects of arterial pressure control, and has proved to be acceptable to the clinical staff.

Algorithms↗
PubMed1995

Three-dimensional simulation of epicardial potentials using a microcomputer-based heart-torso model.

Previous cardiac simulation studies have focused on simulating the activation isochrones and subsequently the body surface potentials. Epicardial potentials, which are important for clinical applications as well as for electrocardiography inverse problem studies, however, have usually been neglected. This paper presents a procedure of simulating epicardial potentials using a microcomputer-based heart-torso model with real geometry. The heart model developed earlier which was composed of more than 60,000 cell units was used in this study. To simulate the epicardial potentials, an epicardial surface model which enclosed the whole heart was constructed. The heart model, together with the epicardial surface model, are mounted in an inhomogeneous human torso model. Electric dipoles, which are proportional to the spatial gradient of the action potential, are generated in all cell units. These dipoles give rise to a potential distribution on the epicardial surface, which is calculated by means of the boundary element method. The simulated epicardial potential maps during a normal heart beat and in patients with left bundle branch block (LBBB) are in close agreement with those reported in the literature.

Action Potentials↗
PubMed2004

The effect of microcomputed tomography scanning and reconstruction voxel size on the accuracy of stereological measurements in human cancellous bone.

Stereological parameters have been used as an approximation for the architecture of trabecular bone. Structural indices such as bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), bone surface-to-volume ratio (BS/BV), degree of anisotropy (MIL1/MIL3), and connectivity density (-Euler/Vol) have been widely studied to investigate pathological conditions in bone. Due to its high resolution and nondestructiveness, microcomputed tomography (micro-CT) has been utilized to take precise three-dimensional (3D) images of trabecular microstructures. However, spatial limitations for applying micro-CT-based analyses to large specimens, such as whole vertebral bodies, require using larger scanning and reconstruction voxel sizes. In this study, combinations of three different scanning and reconstruction voxel size were used to represent best possible voxel size (21 microm; best in our scanner for the specimen size used) relative to other voxel sizes used in this study, commonly used intermediate voxel sizes (50 microm), and those applicable to scans of whole human vertebral bodies (110 microm) in order to examine the effect of scanning and reconstruction voxel size on stereological measures for human cancellous bone. The error in stereological parameters calculated using combinations of large voxel sizes compared to the gold standard (best possible case) ranged from 0.1% to 102%. The signed magnitude of the error in other cases relative to the gold standard was a function of either scanning or reconstruction voxel size or both (r2=0.55-0.95). For most of the structural indices, the results from analysis of images with larger voxel sizes were correlated with those from the gold standard (r2=0.55-0.99) except for Tb.N at 110/110 microm, MIL1/MIL3 at larger than 110 microm reconstruction voxel size, and -Euler/Vol at any combination of voxel sizes. Overall, it was observed that resampling a high resolution image at lower resolutions (corresponding to increasing reconstruction voxel size in this study) had different effects on the calculated parameters than scanning at the same low resolution (corresponding to increasing scanning voxel size in this study). Our results show that investigations of image resolution should include actual scans at the resolution of interest rather than simply coarsening of high-resolution images as is customarily done.

Analysis of Variance↗
PubMed1982

On-line microcomputer system for analysis of precordial maps.

An inexpensive system was developed for automated on-line analysis of ST segment heights, Q, R, and S heights and areas under these peaks, using an LSI-11 microcomputer. System accuracy was evaluated using a computer graphics technique which enabled magnification and labelling of the computed peaks on 60 maps from 17 patients. To compare the computer with hand analysis, the sigma ST (.06 seconds from S nadir) for 20 maps was calculated by three blinded observers. Correct computer evaluation occurred in all but five of 2058 leads. The mean observer sigma ST was 3.2 millivolts (range 0.77-7.5 mv). Mean inter-observer SD was +/-0.21 mv. The mean computer sigma ST was 3.5 mv (range 0.82-9.3 mv). The spread between computer and observer was +/-0.45 mv. Discrepancies between computer and observer were due to cumulative imprecision in observer measurements. This system has proven to be a practical and economic solution to handling the large volume of data accumulated with serial precordial mapping. It is considerably more precise than conventional hand analysis. Additionally, the system's versatility makes it ideally suited to many clinical and research functions.

Computers↗
PubMed1990

Mathematical representation with graphic reconstruction on a microcomputer for an arterial tree.

The branching arterial tree is considered as a collection of numerous points and lines. When treated with vertex analysis, it can be expressed with a new mathematical representation, and graphical reconstruction can be carried out on a microcomputer. This new method is useful for recording an arterial tree precisely on anatomical books or comparing arteries under hypertension with those under normotension in order that the early morphological changes of hypertensive vascular disease can be revealed.

Animals↗
PubMed1987

The adaptation of urethral pressure profiles to detect sphincter incompetence and sphincter obstruction using a microcomputer.

A new system for performing urethral pressure profiles, the fluid bridge test and micturitional urethral pressure profiles has been designed based on the use of a microcomputer. The method described has not only led to major improvement in the presentation and accuracy of these tests but for the first time urethral profilometry has been adapted to detect sphincter incompetence and obstruction in 1 simple method. The fluid bridge test was performed on 46 men and 18 women. The results suggested that this test was excellent for urodynamic evaluation of retrograde ejaculation, post-prostatectomy incontinence and vesicourethral neuropathy, and its value was confirmed in women with stress incontinence. Micturitional urethral pressure profiles were performed in 38 men and 2 women. Not only was this test found to correlate well with conventional methods of detecting obstruction but it was able to diagnose urinary outflow obstruction in patients with equivocal pressure/flow studies and patients with acontractile detrusors. It also allowed diagnosis of the site of obstruction in men with vesicourethral neuropathy without the need for radiological screening.

Computers↗