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Results for “Microcomputers”

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At least 145 records · Page 8Linked to original sources

PubMed1992

Development of an above-knee prosthesis equipped with a microcomputer-controlled knee joint: first test results.

The shortcomings of conventional above-knee prostheses are due to their lack of adaptive control. Implementation of a microcomputer controlling the knee joint in a passive way has been suggested to enhance the patient's gait comfort, safety and cosmesis. This approach was used in the design of a new prosthetic system for the above-knee amputee, and tested on one patient. The knee joint of a conventional, modular prosthesis was replaced by a knee joint mechanism, equipped with a controllable brake on the knee joint axis. Sensors and a microcomputer were added, keeping the system self-contained. The modularity of the design permits the use of an alternative, external, PC-based control unit, emulating the self-contained one, and offering extended data monitoring and storage facilities. For both units an operating environment was written, including sensor/actuator interfacing and the implementation of a real-time interrupt, executing the control algorithm. A double finite state approach was used in the design of the control algorithm. On a higher level, the mode identification algorithm reveals the patient's intent. Within a specific mode (lower level), the relevant mode control algorithm looks for the current phase within the gait cycle. Within a particular phase, a specific simple control action with the brake replaces normal knee muscle activity. Tests were carried out with one prosthetic patient using a basic control algorithm for level walking, allowing controlled knee flexion during stance phase. The technical feasibility of such a concept is illustrated by the test results, even though only flexion during early stance phase was controlled during the trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Artificial Limbs↗

PubMed1993

Microcomputer-based system for automatic analysis of M-mode echocardiograms.

A microcomputer-based system has been developed for automatically analysing M-mode echocardiograms. This system can be used on images directly transferred from an echograph to the microcomputer. To obviate the major disadvantage of echocardiography, its poor signal-to-noise (S/N) level, the system conducts, first, an image restoration based on the quasi-periodicity of cardiac cycles, then border extraction is performed, using methods based on template matching using dynamic cardiac information present in the echocardiograms.

Echocardiography↗

PubMed1984

A low-cost microcomputer system for automated analysis of intracellular cardiac action potentials.

A microcomputer system for automated analysis of action potentials recorded from cardiac Purkinje fibers is described. The system is based upon a DMD 800 microcomputer built around a Z80 microprocessor. Two different sampling intervals are used for analog-to-digital conversion of action potential recorded from driven fibers. The following parameters can be obtained on-line: action potential amplitude; overshoot; maximum diastolic potential; action potential duration measured both at -60 mV and at 90% of complete repolarization; and maximum rate of rise of the upstroke. The digitized form of five consecutive action potentials can be stored on a floppy disk. The automated system eliminates hand measurements; the on-line analysis of the action potentials during pharmacological interventions allows a rapid appreciation of drug effects.

Action Potentials↗

PubMed1983

A microcomputer based system for spike processing at low cost.

A system is described for the quantification of neuronal activity utilizing a microcomputer as an alternative to a conventional hard-wired ratemeter. The system, which counts the number of action potentials occurring in successive epochs, consists of a microcomputer and a small number of external electronic components (e.g. D leads to A chips, counter chips and latches) housed together with the power supply in a subrack. Output is both digital (a video monitor is used to display the count, cumulative count and elapsed time) and analogue (a chart recorder is used to record a frequency/time histogram) for two channels. Variables such as epoch time and analogue output scaling are read in from switches via latches hung onto a data-bus and can be altered without interference with the running of the program. The program is written in BASIC and stored on a C-MOS memory chip. In comparison to alternative storage systems (i.e. cassette and floppy disk) this has the advantage of immediate access and low cost; furthermore the program is readily modified.

Animals↗

PubMed1985

An inexpensive microcomputer-based image-analysis system: novel applications to quantitative autoradiography.

We describe a relatively inexpensive, yet versatile and powerful microcomputer-based image-analysis system, and its applications to processing of deoxyglucose autoradiographic data. Images are acquired via a video camera mounted on a light microscope or a light box, and digitized in 40 ms to 512 X 512 picture elements with 8-bit resolution (256 gray levels). The bit-mapped image analysis hardware can provide up to 256 colors for pseudo-color coding, and virtually instantaneous readout of brightness values for densitometry. The system is controlled by an 8-bit S-100 bus microcomputer, providing flexibility and ease of expansion. In addition to pseudo-color coding and densitometry, we have developed programs for averaging of successive sections, image subtraction and quantitative reconstruction of different planes of section from serial autoradiograms.

Animals↗

PubMed1985

A microcomputer system designed for psychological and behavioural experiments.

This paper describes a relatively cheap MC6809-based microcomputer designed to run experiments in real-time, and to use the hardware and software facilities of a larger (HOST) computer. Each microcomputer is capable of controlling a wide range of psychological and behavioural experiments, and includes 32K RAM, 4K EPROM, 32 digital input lines, 32 digital output lines, analogue/digital converters, and programmable timers. Any programming language may be used, providing a cross-compiler generating MC6809 executable code exists for the HOST. Following over a year of use we can confirm that this system provides an effective method of running psychological and behavioural experiments.

Computers↗

PubMed1986

An inexpensive and interactive microcomputer system for codifying Golgi-impregnated neuronal morphology.

An interactive microcomputer system has been developed for the quantitative analysis of Golgi-impregnated neuronal morphology (GINM). The system uses commercially available hardware: a 48K RAM microcomputer (Apple II), a TV monitor (NEC), an optical microscope (Reichert Biovar) with a camera lucida and a specially developed wheel attached to the focus adjustment knob and to a digital planimeter (Tamaya), allowing one to obtain the value of the z-coordinate. The x- and y-coordinates are obtained using the movement of a point plotted by the computer on the TV monitor. This point is superimposed upon the GINM point to be codified employing the camera lucida. The x- and y-coordinates are acquired automatically while the variations of the z-coordinate are introduced by the computer keyboard. The three-dimensional coordinates of the selected GINM points and different codes are stored by the computer in a six-dimensional array. The software is written in BASIC. The results demonstrate that the digitization and quantitative analysis of GINM can be achieved with reasonably inexpensive equipment.

Animals↗

PubMed1987

Acquisition and analysis of fast single channel kinetic data on an Apple IIe microcomputer.

We describe a method for acquisition and analysis of single channel kinetic data, that uses a ubiquitous microcomputer, the Apple IIe (and is thus cheap), and is yet sensitive and powerful (analysis of up to 6000 events per run of the program; event detection only limited by the amplifier bandwidth). For data acquisition, the original record is converted into an idealized record of open and closed times, using half amplitude threshold analysis or a two-cursor window discriminator. A Time Interval Meter (TIM) has been developed that measures the durations of the TTL-signal from the window discriminator and stores up to 256 intervals in a FIFO-buffer. Each cycle of the TIM is completed within 1 microsecond. The, largely Pascal, software reads the intervals from the FIFO-buffer and stores them in the main memory of the microcomputer (cycle time 70 microseconds). The package is completed with Pascal programs for statistical analysis, including histogram construction of open and closed times, non-linear fit of up to 3 exponentials and correlation analysis.

Computers↗

PubMed1989

Microcomputer-controlled laboratory system for field potential experiments.

A microcomputer-controlled laboratory system for hippocampal field potential experiments was constituted. This system realized the quasi-simultaneous processing of execution of stimulation, data acquisition, data display and data analysis by means of a microcomputer for the first time. To attain this quasi-simultaneous processing, a new algorithm for drawing a tangent on the wave-form of the potential was contrived, which enabled rapid analysis of an arbitrary population spike even in the case of generation of double spikes. The system has the following functions: (1) execution of the programmed stimulation paradigm, (2) analog/digital (A/D) conversion of the evoked field potential with a sampling interval of more than 50 microseconds per channel, (3) display of the A/D converted wave-form data on a CRT and storage of the data on a floppy disk, (4) on-line analysis of the population excitatory postsynaptic potential (EPSP) and population spike, (5) more detailed off-line analysis of the field potentials, and (6) output of the wave-form data and measured values through a printer and an X-Y plotter.

Action Potentials↗

PubMed1989

Enhancing high-speed digitization of single-unit neuronal activity on a microcomputer using a hybrid software-hardware technique.

A new data acquisition technique allows a microcomputer simultaneously to digitize spikes at high rates, analyze spike waveforms for computer-based spike separation and manage other control tasks. The technique has two key features: a software scheduling routine written in a high-level language and a hardware analog delay of neuronal signals using simple hardware external to the computer. The technique provides an alternative for real-time data acquisition and can be used on microcomputers without requiring interrupt processing and assembly language programming.

Action Potentials↗

PubMed1990

On-line acquisition, analysis and presentation of neurophysiological data based on a personal microcomputer system.

A microcomputer based system is described for the acquisition, averaging, displaying, analysis and storage of electrophysiological (EPSP and post-stimulus histogram) data. The system consists of commercially available hardware (IBM-PC AT compatible, 80286 or 80386 based microcomputer, Burr-Brown analog-to-digital (A/D) converter), a custom built interface module, and a combination of commercially available and custom built software packages. The software operates within a Microsoft Windows environment and is comprised of custom built data acquisition and review modules which are linked to Microsoft's Excel program. The system is capable of four channel A/D conversion of EPSP's at a sampling frequency of up to 10 KHz (50 KHz single channel), the averaging of data including the addition and subtraction of various channels, the graphical display of data, the extraction of various data parameters, and the transfer of data to an Excel spreadsheet. The spreadsheet allows for the development of mathematical formulas for statistical analysis of data and presentation of the results in graphical form. Finally, data can easily be output to a laser printer or plotter. A sample experiment, illustrating system operation, is presented.

Electronic Data Processing↗

PubMed1994

Automated nerve fibre size and myelin sheath measurement using microcomputer-based digital image analysis: theory, method and results.

In either clinical or research settings, manual measurement and counting of myelinated fibres in peripheral nerve is tedious and error-prone, yet fully automatic computerized counting and measuring of fibres fails to count small fibres and eliminate extraneous profiles in the tissue. This article describes an operator-interactive, semiautomated method for quantification of myelinated nerve fibre data using commercially available hardware and software on an inexpensive, yet full-featured image analysis system based on a microcomputer. Software macros automate the acquisition of data from the microscope images and the production of numerical and graphic data, with output to either paper hardcopy or 35 mm colour slides. User control is retained for dynamic thresholding, binary image creation and elimination of artifacts. In addition to generating the classic histogram showing the size distribution of nerve fibres, the thickness and variability of myelin sheaths are also graphically depicted. The method is based on measurement of myelin area and total perimeter, with calculation of equivalent circles and diameters for both axon and nerve fibre. Measured fibre sizes are thus somewhat larger than those resulting from manual methods using the minor diameter of an oval profile, or mean diameter of crenated or irregular profiles. The method allows the rapid measurement and counting of numbers of fibres previously impossible to assess manually, or using digitizing tablets. By increasing the speed and accuracy of data acquisition and processing using widely available microcomputers, the method may allow a better description of peripheral nerve changes in research and clinical settings.

Analog-Digital Conversion↗

PubMed1994

A system for quantitative analysis of associative learning. Part 2. Real-time software for MS-DOS microcomputers.

Microcomputer software was designed and used to control the timing and delivery of sensory stimuli and to acquire and analyze behavioral data during classical conditioning experiments. The software package runs under DOS 4.x through 6.x (earlier versions run under DOS 3.x) on PC AT-compatible microcomputers coupled with appropriate interface hardware (see Thompson et al., 1994). The software controls timed delivery of up to 8 conditional stimuli. It can collect behavioral data from 2 subjects simultaneously performing the same task (e.g., eyeblink responses) or from a single subject performing 2 different tasks (e.g., both eyeblink and conditional discrimination tasks), permitting its use in a number of experimental paradigms. Digital timing signals are adjustable for different stimulus output systems. Behavior is continuously monitored onscreen, ensuring consistent measurement across trials. Real-time performance measures of the presence or absence of conditioned responses allow coordination with external events (e.g., serum sampling, drug delivery, or single-unit recording). Quantitative measures are generated both for each trial and for complete sessions. Records are stored to disk and can be printed or merged for statistical analyses. Data can be archived on standard media, and internal software utilities translate files for export to PC and Macintosh programs. This system and the hardware described in the preceding paper combine ease of use with extremely replicable behavioral measurements across trials, sessions subjects, cohorts, and studies.

Animals↗

PubMed1987

Real-time acquisition and analysis of cardiac action potentials and twitches using a programmable digitizer and a microcomputer.

Action potentials and single twitches from papillary muscles were acquired and analyzed in real-time using a programmable digitizer and a microcomputer. This combination provides greater control and flexibility during data acquisition than standard analog-to-digital converters. The present system was designed to facilitate evaluation of experimental drugs. However, the combination of a programmable digitizer and a laboratory microcomputer can be applied to a variety of applications in biomedical research.

Action Potentials↗

PubMedDate not supplied

BACTID: a microcomputer implementation of a PASCAL program for bacterial identification based on Bayesean probability.

A computer program (BACTID) is described which enables the identification of bacteria based on a priori data and Bayesean probability testing. The program is not limited to a specific format, has a short execution time, can be easily applied to a variety of situations, and can be run on almost any microcomputer system operating under either 8-bit CP/M or 16-bit MS-DOS or PC-DOS. Additionally, BACTID is not limited to one type of computer (hardware independent); is not limited by size of the computer's random access memory (RAM independent); can recognize various database matrices (format independent); is able to compensate for missing data; and allows for various methods of data entry. The efficacy of the program was checked against a commercially available test system and a 99.34% agreement was obtained. Also, the execution time for a 46 x 21 data matrix was as little as 3.5 seconds. These results show that microcomputer identification programs not only are viable alternatives to code-book registers, but also offer flexibility which is not found in commercial systems.

Bacteria↗

PubMedDate not supplied

Microcomputer-assisted univariate survival data analysis using Kaplan-Meier life table estimators.

We describe a microcomputer program (KMSURV) for exploratory univariate statistical analysis of survival data which is directly applicable to the evaluation of clinical trials and to retrospective epidemiological studies of hospital registry-based data. The program calculates life-table-like information based on Kaplan-Meier's product-limit estimators of the survivorship function S(t) and provides summary measures of average survival times. In addition, two non-parametric tests for the comparison of survival distributions are performed. A report-quality, high resolution plot of the S(t) estimates for all groups being compared complements each set of analyses. KMSURV is not a simple adaptation of a mainframe statistical analysis package and, thus, it utilizes efficiently the interactive environment which is inherent in microcomputing.

Actuarial Analysis↗

PubMedDate not supplied

RIAPC: a microcomputer program for the analysis of radioimmunoassay data.

A microcomputer program for analysis of radioimmunoassays has been developed for use on microcomputers which operate under MS-DOS system software. The program messages are contained in an ASCII text file in French, English, and Spanish and can be modified by the user. The parameters and data can be entered manually into screen tables, or read from external files. An unweighted log/logit transformation is used for regression analysis of the standard curve. Provision is made for correction of the sample measurements for procedural losses (recovery). All results are written to an ASCII text file which can printed and/or reduced in order to pass the sample concentrations to other programs.

Humans↗

PubMed1987

Prevalence survey of infection in a Hong Kong hospital using a standard protocol and microcomputer data analysis.

A 1-day prevalence survey of hospital infection was performed in June 1985 at a new general teaching hospital in Hong Kong. The 1980 British national survey protocol was used, and the results were analysed by microcomputer. The major part of the survey was carried out by nine people over a period of 3 days and was completed within 6 weeks. The rate of hospital-acquired infection was 8.9% and of community-acquired infection was 16.5%. Antibiotics were mainly used in infected patients. The British protocol is suitable for Hong Kong hospitals, and with microcomputer data analysis such surveys can be completed quickly and accurately even with limited resources.

Adolescent↗