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PubMed1989

Microcomputer programs for complex epidemiologic procedures. II. Test for equality and trend of adjusted rates.

The microcomputer program presented in Part I of this series (M. H. Dong, Comput. Biomed. Res. 22, 349 (1989)) is useful for computing adjusted excess rates. That program, however, does not provide a means for a quantitative analysis of the adjusted rates computed for the categories of a risk factor. At times it is crucial for us to determine whether after adjustment a factor exerts a dose-response effect that is statistically significant. Recently a hypothesis test for analyzing such an effect has been reported. The test is based on score statistics obtained directly from a product model assumed for the excess rate. The objective of this second part is to continue to make available a microcomputer program that has been written to implement the computation of these score statistics, which likewise entails a complex and lengthy iterative procedure. In this communication the test is described and the application of the microcomputer program is illustrated.

Biometry↗
PubMed1989

Pharmacokinetic analysis of single- or multiple-dose plasma drug concentration data with a microcomputer using multi-fraction absorption models.

A Basic program for multi-fraction absorption models was developed to link with another microcomputer program, MULTI, and was named MFA-MULTI. A main frame computer program SIMP, based on a simplex method using differential equations, was also operated using a microcomputer equipped with a FORTRAN compiler and a 8087 floating-point coprocessor. These two programs [MFA-MULTI and SIMP (M)] were applied to the analysis of plasma concentration data of several drugs with irregular absorption profiles. The results by MFA-MULTI and SIMP(M) for the single- or multiple-dose data were almost coincident with those obtained by a SIMP program. The result for nalidixic acid estimated using MFA-MULTI or PKM-MULTI was also compared. The plasma nalidixic acid concentration, with irregular absorption profiles due to characteristics of dissolution in the gastrointestinal tract, was found to be described by a two-fraction absorption model. The MFA-MULTI program was applied to the analysis of plasma cimetidine concentration data with double peaks in humans. Pharmacokinetic absorption behavior of a sustained-release preparation of theophylline after repetitive oral administration was adequately evaluated using MFA-MULTI. In addition, application of multi-fraction absorption models to population pharmacokinetics is discussed.

Administration, Oral↗
PubMed1990

The use of laboratory microcomputers to hold NMR data bases.

Computer-based data bases are essential tools for NMR spectroscopists working with complex mixtures such as tissue extracts. Algorithms are described which are easily implemented on a small laboratory microcomputer and which can be used to make, edit, and query personalized laboratory data files. The data are stored in a series of small files accessed by pointers to overcome inherent redundancy in the information. Performance times are tabulated for a BBC Model B microcomputer working in the BASIC language and using 5.25-in. floppy discs as virtual memory.

Algorithms↗
PubMed1989

A microcomputer system for clinical signal analysis of vestibular laboratory.

A vestibular laboratory system was implemented for clinical testing and medical examination of patients with balance disorders. Programs for analysis of postural control and eye movements were made for a microcomputer. The microcomputer system can be used by a nurse without technical education. The system has now been used for two years at the laboratory.

Eye Movements↗
PubMed1991

A new method for analyzing smooth-pursuit eye movements. Description of a microcomputer program and evaluation in healthy volunteers.

The study of ocular movements has been increasingly used to detect subtle pathological modifications, caused by a wide variety of neurological diseases. We have developed a new microcomputer-based method for the analysis of smooth-pursuit ocular movements induced by constant velocity targets moving unpredictably at different velocities (including velocity values as high as 100 deg/s). The ocular movements are recorded by an electro-oculographic technique using silver-silver chloride electrodes fixed near the inner and outer canthi of both eyes. The signals are amplified by two DC amplifiers after a low-pass filtering (50 Hz), sampled at 250 Hz and digitized in a 12-bit form by an analog/digital converter. For each patient's evaluation, a series of 20 sweeps of the target is generated. The data analysis, which is performed automatically by the microcomputer, is based on the calculation of four parameters: average peak eye velocity (APEV); typical target velocity (TTV); percent target matching index after saccade removal (PTMI); typical matching target velocity (TMTV) after saccade removal. APEV is calculated as the average of the peak velocities estimated from the 20 sweeps. The purpose of TTV, which is defined as the value of target velocity at which the percent gain has decreased to slightly more than one third of the maximum percent gain, is to provide an overall index of the rate at which the percent gain decreases as the target velocity increases. PTMI describes the eye performance for each value of target velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Advanced microcomputer-aided medical illustration.

In a visually oriented field such as diagnostic radiology, illustrations, diagrams, and other types of art-work can complement verbal description and photographs, simplify the description of anatomic concepts, and add interest and aesthetic value to a presentation or manuscript. The vast potential of the microcomputer for creating high-quality art and graphics is being realized by the availability of high-level illustration programs running on fast computer systems. Advanced microcomputer applications for illustration have the tools to compose and execute drawings of virtually unlimited detail and complexity. Digitized images can be used as drawing templates or as components of finished art. Text is easily incorporated. Each individual element of a drawing can be changed or edited without altering other portions of the drawing. finished art can be output to laser-xerographic printers, film recorders, and photo imagesetters.

Computer Graphics↗
PubMed1979

EEG data acquisition and preprocessing by microcomputer satellite system.

Recent development in computer technology allows already medium scale EEG data processing to be performed within the clinical neurophysiology department, if a fast minicomputer with adequate mass storage and graphical output facilities is used. Data acquisition, however, should be delegated to a microcomputer which also should take over as much preprocessing as possible. A system is presented, where one or several microcomputer-based satellite units perform analog-digital conversion, Fourier transformation (FFT), calculation of power spectra and crossproducts, as well as event related averaging or other preprocessing procedures. The units are connected to a fast central minicomputer, where a supervisor program loads the microprocessors with their programs, supervises their activity, receives preprocessed data and activates appropriate postprocessing programs to produce the final results.

Analog-Digital Conversion↗
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↗
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↗
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↗
PubMed1990

A microcomputer application curriculum for emergency medicine residents using computer-assisted instruction.

A microcomputer application curriculum using computer-assisted instruction was developed for emergency medicine residents. Other than introductory comments, the course was composed entirely of disk-based tutorials. No faculty time was necessary. Subjects covered included introduction to microcomputers, the disk operating system; word processing, data bases, and spread sheets. The entire course, including the tutorial floppy disks, was contained in one loose-leaf notebook. Residents who took the course were surveyed. The course took an average of three to six hours to complete. All found the course to be helpful, with word processing being the most useful module. The majority of residents thought that the course was so valuable that it should be given earlier in the residency. Thus, we have moved the course to the first postgraduate year, and the data base and spread-sheet modules have been made optional. The course is easily assembled, requires minimal faculty time, and can be modified to accommodate different hardware and software.

Computer-Assisted Instruction↗
PubMed1989

Resolving multiple overlapping calorimetric transitions by use of a microcomputer: studies on erythrocyte membranes.

Buffer changes and certain drugs cause temperature shifts, amplitude changes, and transition broadening in the differential scanning calorimetric (DSC) analysis of erythrocyte membranes. However, it has been difficult to interpret and quantitate these shifts and changes because the scans are composed of multiple overlapping transitions and because more than one transition may be simultaneously affected. An empirical approach has been developed by using Gaussian modeling to resolve these calorimetric transitions. Data analysis was carried out on a microcomputer using a nonlinear regression program (PCNONLIN) to fit the data scans. These results show that changes in the calorimetric scans of erythrocyte membranes due to alterations in the buffer environment, such as pH and osmolarity, can be resolved by fitting the data scans with the proposed mathematical model and optimizing the resolution parameters with PCNONLIN. In addition, resolution uncovered hidden characteristics that may not have been readily evident. Under certain conditions, for example, apparent transition shifts were shown to actually be amplitude changes and transition broadening. Determination of the limitations and validity of this method was accomplished with simulation studies. This technique offers a simple means for fitting overlapping DSC transitions by use of a commercially available nonlinear regression program that can be run on a microcomputer.

Buffers↗
PubMed1989

Tabletop versus microcomputer-assisted speech management: stabilization phase.

Few controlled data are available on the efficacy of microcomputers for speech management with children. The focus of this second report in a study series using microcomputers with speech-delayed children (Shriberg, Kwiatkowski, & Snyder, 1986) is on the response stabilization stage of speech management. Two repeated-measures designs were conducted with two samples of preschool children (n = 18) to compare tabletop management with comparable computer-assisted activities. Findings indicate that response stabilization tasks in the two intervention modes were equally effective, efficient, and engaging. Additional analyses suggest that the two modes engage the children in different ways, however, and that children may have individual needs for mode-specific features.

Age Factors↗
PubMed1991

A model of a microcomputer database system to assist medical schools in recruiting and retaining students.

A model for a microcomputer database to aid a school's efforts to recruit and retain students is presented. The model is based upon a working system developed by the author at the University of Colorado Health Sciences Center. The article discusses data needs for adequate records of the recruitment and retention efforts, especially those concerning minority students, and how these records can be used to administer and evaluate programs. The model provides a framework for microcomputer data files, record fields, relationships, and system development and maintenance considerations.

Colorado↗
PubMed1989

A microcomputer algorithm for solving first-order compartmental models involving recycling.

A general algorithm for solving first-order compartmental models including recycling systems has been developed and its implementation on a microcomputer is described. Matrix algebra is used to obtain for any compartmental model an analytical solution, which is expressed as the exponential of a matrix of rate constants. A special technique is used in the algorithm to enable this exponential to be evaluated with a rapidly converging series. Truncation errors incurred in this process are estimated automatically. Thus, in an extreme case, where these errors may be significant, the appropriate action can be taken. Given a particular model, the user enters the model parameters into a rate matrix according to a simple rule. The algorithm then uses this matrix to solve the model, and thus no specialized mathematical knowledge is needed. The algorithm is given in a short BASIC program (60 lines) listed in an appendix. No additional software is required. By running this program on a standard microcomputer, the user can solve models of any complexity: those up to 15 compartments in seconds and those up to 30 compartments within a minute. The algorithm is thus ideally suited to solve kinetic models describing the transport of radionuclides in the environment or the translocation of elements in biological systems such as the metabolic models recommended by the International Commission on Radiological Protection (ICRP). Given the initial amount of material in each compartment at time t = 0, together with its radioactive decay constant, the algorithm gives both the amount in each compartment at any future time t and the number of disintegrations that will have occurred in each compartment up to time t. The computer program, shown in an appendix, could easily be used to calculate disintegrations over any time interval of interest, or to predict the quantities or fractions of an intake expected to be present in any in vivo or excretion compartments of interest. Thus, the algorithm can be useful in both the design and conduct of bioassay and internal dose assessment procedures.

Algorithms↗