Small Laboratory Computer Research Articles

Triggering module for waveform digitization

A full circuit description is provided for a triggering module used to assist a small laboratory computer in digitizing muscle force- and EMG waveforms. During the stimulation of individual motor units using a standard fatigue test, a train of 13 pulses are delivered at a rate of 40 pps either intracellularly to a motor neuron, or extracellularly to functionally isolated single motor axons from among divided ventral-root nerve filaments. Trains are delivered at a rate of 1/s for the duration of the test, which may range from 120 to 3600 s. Both the force and EMG profiles undergo changes during such tests and the quantification of parameters associated with their waveforms are of interest to neurobiologists. The triggering module allows a typical small laboratory computer to capture user-selected waveforms and thereby reduces the programming problems, timing constraints, storage requirements and analysis time associated with obtaining these parameters. The versatile circuit may be easily adapted to solve similar data-acquisition problems. The method was implemented on an Apple Macintosh II computer but can also be applied to other systems equipped with appropriate software and a data-acquisition card.

A method for separation of superimposed electromyographic responses in man

Superposition of electromyographic potentials occurs when motor nerves are excited at intervals that are shorter than the duration of one single muscular signal. The method introduced here allows the separation of compound responses into their constituents in experiments with two closely spaced stimuli (conditioning stimulus and test stimulus), each of them eliciting a defined electromyographic response. Stimulus generation is controlled by a small laboratory computer which produces paired stimuli or the conditioning stimulus alone in random order. All responses are classified according to the size of the initial part of the response to the conditioning stimulus and averaged. The response to the test stimulus is obtained by a subtraction procedure. The method takes into account the considerable variability of reflex responses in man. It was tested in the analysis of recovery curves of spinal reflexes elicited by short vibratory pulses onto the tendons of relaxed human arm muscles.

Design and characterization of x-ray multilayer analyzers for the 50–1000 eV region

This report describes a synthesis of more than 10 years of this program's development and application of multilayer analyzers for absolute Bragg spectrometry in the low-energy x-ray region of 50–1000 eV. Multilayers, defined here as systems of periodic layered structures parallel to the analyzer surface, have been applied principally in the diagnostics and application of the new, intense sources of synchrotron and high-temperature plasma x radiation. Detailed absolute reflectivity characterizations are presented for selected examples of these multilayers which have been semiempirically determined for mica, potassium acid phthalate, and the fabricated Langmuir-Blodgett and sputtered multilayer analyzers with d-spacings in the 10–200 Å range. Design requirements for absolute spectrometry are established. Efficient analytical multilayer reflectivity models are derived and parameterized (based upon a modification of the Darwin-Prins model for the low-energy x-ray region), including, for the sputtered multilayers, parameters for denning interface structure. The dependence of the reflectivity characteristics, high-order Bragg diffraction suppression, and overall efficiency upon the model parameters is analyzed. A special spectrograph and procedure for the absolute measurement of the relevant reflectivity characteristics are described. Detailed measurements and semiempirical characterizations are presented. Programs for small laboratory computers have been developed that allow rapid and flexible spectral analysis, transforming measured spectra to absolute spectra.

Design and Characterization of X-Ray Multilayer Analyzers for the 50–1000 eV Region

This report describes a synthesis of more than 10 years of this program's development and application of multilayer analyzers for absolute Bragg spectrometry in the low-energy x-ray region of 50-1000 eV. Multilayers, denned here as systems of periodic layered structures parallel to the analyzer surface, have been applied principally in the diagnostics and application of the new, intense sources of synchrotron and high-temperature plasma x radiation. Detailed absolute reflectivity characterizations are presented for selected examples of these multilayers which have been semiempirically determined for mica, potassium acid phthalate, and the fabricated Langmuir-Blodgett and sputtered multilayer analyzers with d-spacings in the 10-200 Å range. Design requirements for absolute spectrometry are established. Efficient analytical multilayer reflectivity models are derived and parameterized (based upon a modification of the Darwin-Prins model for the low-energy x-ray region), including, for the sputtered multilayers, parameters for defining interface structure. The dependence of the reflectivity characteristics, high-order Bragg diffraction suppression, and overall efficiency upon the model parameters is analyzed. A special spectrograph and procedure for the absolute measurement of the relevant reflectivity characteristics are described. Detailed measurements and semiempirical characterizations are presented. Programs for small laboratory computers have been developed that allow rapid and flexible spectral analysis, transforming measured spectra to absolute Spectra.

Use of digital filtering techniques in the spatial profiling of pulsed laser beams

A method of spatially profiling pulsed laser beams using a digital filtering technique is described. This technique has the advantage of requiring fewer experimental scans of the laser beam to produce usable lownoise replicas of the laser beam's spatial profile than previously described methods. The technique is simple and can be implemented on a small laboratory computer.

Mechanism of oxidation of ferrous polydentate complexes by dioxygen

Oxygen is completely reduced to water in four steps during the oxidation of polydentate ferrous complexes to their corresponding ferric complexes. Only the first two steps are kinetically important, since the succeeding reaction involving peroxide is fast. ▪ ▪ ▪ Between pH 3 and 7 all three rate parameters, k 1, k −1, and k 2, can be significant kinetically. The value of k 1 depends on the standard potential of the iron complex system, being fastest for EDTA, k 1 = 63 M −1 s −1, and slowest for PDTA, k 1 = 0.68 M −1 s −1. Both k −1 and k 2 are pH dependent owing to protonation of the superoxide radical, p k = 4.7. The value of k −1 for oxidation of superoxide radical anion is between 2 × 10 6 M −1 s −1 and 6 × 10 6 M −1 s −1, except for the DTPA complex, which is 100 times slower. The pH-independent values for k 2 above pH 5, where O √−1 2 is the active oxidant, range from 1.2 × 10 8 M −1 s −1 for EDTA to 3.5 × 10 5 M −1 s −1 for PDTA and 1.0 × 10 5 M −1 s −1 for MIDA. The slow values of k 2 for ferrous PDTA and ferrous MIDA and the correspondingly large values of k −1 for these complexes make k 2 rate-determining for oxidation, yielding an overall reaction which is second order in ferrous ion. For ferrous EDTA and DTPA, k 1 is the rate-determining step, unless high concentrations of ferric ion are present initially, and the reaction is first order in ferrous ion. Oxygen is maintained at its saturation concentration in solution by vigorous sparging, and the loss of ferrous ion is followed electrochemically at a rotating pyrolytic graphite electrode. Data are gathered and analyzed on a small laboratory computer. Implications of this chemistry for the catalysis of superoxide dismutation are discussed.

Resolution of overlapped chromatograms by means of the kalman filter : Dimensional reduction of error covariance matrices and state estimate vectors

If many samples are successively injected into a high-performance liquid chromatograph at short intervals, then overlapped chromatograms will be obtained. A simplified version of the Kalman-filter algorithm is described for rapid resolution of several such overlapped peaks on small laboratory computers; the dimensionalities of the error covariance matrix P k and state estimate vector X̃ k are reduced to far less than the total number of the peaks. Computer simulation shows that at least twenty partially overlapped Gaussian peaks, used as a model of the successive injections can be successfully resolved, with the 4 × 4 matrix P k and 4-vector X̃ k. This version is independent of the number of injections and is effective for the resolution of a finite number of peaks in that injection mode. The algorithm of small dimensions is applicable to a wide variety of peak resolution procedures.

Proton coupling constant extraction. A fast method for analyzing ESR spectra by computer

Proton coupling constant extraction (PCCE) is a novel computer method for obtaining all the proton hyperfine coupling constants in an electron spin resonance spectrum. PCCE works well on spectra which are poorly resolved, and thus appears to complement the recently developed correlation approach used for very well resolved spectra. No prior knowledge of radical structure is needed, and proton splittings are clearly discriminated from spin-1 splittings. The program consists of two parts: SEARCH, to identify the proton hyperfine splittings, and SEPARATE, to simplify the ESR spectrum. PCCE is readily programmed and run on a small laboratory computer. Copies of the BASIC subroutines are available on request.

さ声の質と量の客観的評価法

A spectrogram of a normal sustained vowel, taken with a narrow filter, shows welldeveloped harmonics as equally spread horizontal stripes, while that of a hoarse voice presents the noise components as a cloudy shadow between harmonics. A small laboratory computer was used to evaluate hoarseness objectively. Three pitch periods extracted from the voice waveform were analized at up to 5.5KHz harmonic frequency by Fourier Series Expansion. Since it offers a dispersal spectrum with good frequency resolution, the acoustic energy of the harmonics is calculated separately from that of the noise components. This study was carried out in 28 normal subjects and 30 patients. The ratio of harmonics to noise (Ra) of the normal group ranged from 15.0 to 23.5dB, and in 95% of normal cases the Ra value renged from 15.4 to 23.3dB. With this criterion, pathologic voices could easily be differentiated from normal. The Ra value also showed a definite correlation with the auditory impression and the visual impression of the spectrogram, suggesting that this is a useful tool in quantitative evaluation of the degree of hoarseness.Furthermore, the relation between the distribution of the noise energy and the voice quality in each case was investigated. The ratio of harmonics to low frequency noise components below 1.38KHz (RL) corresponded well with the R factor (roughness) of the auditory impression, while that of harmonics to high frequency noise components above 1.38KHz (RH) correlated well with the B factor (breathiness). More detailed investigations of noise energy would probably increase the success of differentiation among various laryngeal diseases.

Charge distribution on a fiber

The charge distribution of a single line of equal charges was determined using a small laboratory computer. Two basic assumptions were made about the distribution and symmetry of the charges on a straight line. Using Coulomb's law, a matrix was set upas a function of the unknown charges and the relative distances between each charge. The results show that the charge at the ends is almost double the value of those in the center. The tension is uniform, i.e., the net force on each internal charge is zero, along the entire length of the fiber, and the potential field differs only slightly from that of a uniform charge distribution.

A simple hidden line removal algorithm for serial section reconstruction

A simple and efficient program for removing the hidden lines from the computer graphics display of a three-dimensional structure has been developed. The algorithm is optimized for serial section reconstruction, that is, for three-dimensional structures composed of a series of stacked planar outlines. Using the algorithm, an anatomist can generate a realistic static picture of a reasonably complex reconstruction in about 20 s on a small laboratory computer.

Orthogonal polynomials used as soft tissue energy density functions

A mathematical method is developed for computing the coefficients of soft tissue energy density polynomials, satisfying certain constraints. The polynomial coefficients are computed in the least squares sense. It is demonstrated that this method: (a) determines up to 30 polynomial coefficients whereas the unmodified least squares method based on Maclaurin power series determines up to nine coefficients; an (b) increases numerical stability and accuracy by several orders of magnitude. All computations are carried out in single precision on a LS1-11/23 laboratory minicomputer. The algorithm is particularly useful for on-line data analysis using small laboratory computers.

A general signal-processing unit for electrophysiological measurements

A multipurpose electrophysiological signal-processing system using a small laboratory computer is presented as an essential tool for a new approach to medical instrumentation. The use of such a general measuring system for different diagnostic methods in the hospital instead of speial-purpose equipment for each method is elucidated, and hardware and software requirements of the system are defined. The hardware and software actually implemented in the system are described briefly, particular attention being paid to special software developments. Problems of software development and maintenance are discussed.

Applications of a signal averager for neurophysiological investigations in clinical function laboratories using a general signal-processing unit

A general ‘coherent signal averager’ software package which can be run on a small laboratory computer is presented as an application of a new approach to medical instrumentation. The combination of the minicomputer, preprocessing hardware and the above-mentioned software yields a flexible multipurpose averaging system for electrophysiological signals. The possibilities of the system are discussed with reference to visual evoked potential measurements in a clinical function laboratory.

Small laboratory computer automation system based on Hewlett-Packard HP-1000 mini computer and IEEE-488 standard

A system for automatic acquisition and handling of experimental data based on the Hewlett-Packard HP-1000 minicomputer and IEEE-488 standard is described. Digital measuring equipment is coupled with the computer through the Hewlett-Packard Interface Bus (HP-IB). The special IPP interface is developed to connect to the computer the devices which are noncompatible with HP-IB. Two types of IPP interface are described — a parallel and a series one. Any number of devices placed at any distance can be connected with the computer through the serial line.

Data handling and reporting for microbiology specimens with a small laboratory computer system.

A small laboratory computer system designed for general application in chemistry, haematology, and urinalysis has been adapted for the bacteriology section of the laboratory using the same available programming routines. Specimens are requisitioned according to predetermined common site codes, with both preliminary and final reporting allowed for where desired. Sensitivity data also appended and entered where required, even for different organisms in the same culture.

Computerized analysis of sleep recordings applied to drug evaluation: midazolam in normal subjects.

Computerized analysis of polygraphic sleep recordings was carried out for the evaluation of midazolam, a benzodiazepine hypnotic. The analysis was carried out in real time on a small laboratory computer, and the output included the hypnogram and relative power profiles for the main electroencephalogram activities. Analysis showed a slight "intranight rapid eye movement rebound" during medication and reduction of sleep stage IV after withdrawal. The relative power of the delta frequency band did not change during medication or withdrawal.

Computerized method for scoring of polygraphic sleep recordings

A new method for automatic analysis of polygraphic sleep recordings is described. The analysis is to be carried out on a small laboratory computer in two phases. The first phase is a real-time signal processing during which the EEG signal is being divided into quasi-stationary segments of uneven length and homogeneous in their spectral content, and the EOG and EMG signals analysed. The second phase is a very short off-line operation, comprised of sequential clustering of the segments, using fuzzy subset theory, and optimal fuzzy partition. The output available is the hypnogram, describing the sequence of sleep stages during the night, graphs describing the relative power changes of the main EEG activities (delta, theta, alpha and sigma), and 3-dimensional plots of the spectral changes during the night. In addition, a few quantitative measures related to the relative amount of the various sleep stages and to the number of rapid eye movements are calculated.

A program for sampling, assessment of stationarity and variability analysis of neuronal spike trains, run under control of a time-sharing system

A system has been developed for off-line analysis of discharge characteristics of continuously firing nerve cells. The programs, which are mainly written in FORTRAN IV, determine mean firing rates, variability and other parameters of the impulse activity and contruct interspike interval histograms. They are run under time-sharing on a small laboratory computer. To disclose possible non-stationarities in the data all interspike interval samples are analysed with the non-parametric Kolmogorov-Smirnov test. This test is very powerful in detecting any differences between two samples and is still very easy to implement in programming. Raw data and computed statistics are stored in random access data files.

Electromyogram processing for sleep research

A computer method for quantifying the submental electromyographic surface interference pattern (EMG) during sleep and wakefulness by amplitude envelope measurement for consecutive 2-sec intervals is described. The method is largely insensitive to electrocardiogram (EKG) artifact. Though this algorithm was developed as part of a program to detect electroencephalographic (EEG), electrooculographic (EOG), tonic and phasic EMG changes during sleep, the method is applicable by itself wherever the envelope width of the EMG interference pattern is of interest. The results obtained correlate well with visual estimates of the amplitude envelope of the raw EMG. It offers increased speed, accuracy and reproducibility compared to visual EMG evaluation and enables a high degree of information extraction. The simplicity of the algorithm permits implementation and on-line processing on a small laboratory computer.