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Results for “Analog-Digital Conversion”

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At least 433 records · Page 24Linked to original sources
PubMed1987

A multichannel PWM telemetry system for kinematic gait analysis.

A multichannel biotelemetry system using pulse-width modulation-frequency modulation (PWM-FM) is described in detail for laboratory construction. Its application in a kinematic gait-analysis system is demonstrated, employing minimally encumbering electrogoniometry and foot-contact switches. The triaxial electrogoniometers sense rotational joint motion, and four foot-switches under the sole of each foot provide information on placement and temporal contact. Signals from the multiple sensors are amplified, encoded by pulse-width modulation, and transmitted at an FM radio frequency of 107 MHz. Received data are decoded and then sampled by a minicomputer for analysis. Results from a comparative study of kinematic gait in five normal subjects and five children with cerebral palsy demonstrate system effectiveness in providing quantitative data and various intrasubject and intersubject gait differences. Factors reviewed in the analysis include swing and stance times; cadence; hip-joint motion in sagittal, coronal, and transverse planes; and sequence of foot placement.

Analog-Digital Conversion↗
PubMed1987

Digital radiography.

Explore the source record for details and available documents.

Analog-Digital Conversion↗
PubMed1987

[Intravenous digital subtraction angiography].

Thanks to its high contrast resolution, intravenous digital subtraction angiography (IV-DSA) makes it possible to examine the arteries after injection of contrast media into a peripheral arm vein. IV-DSA is indicated in patients with clinical suspicion of arterial stenosis, occlusion, aneurysm or anomaly (ascending and descending aorta, aortic arch and its great vessels, and the renal, iliac, femoral and popliteal arteries). In many such patients, IV-DSA successfully replaces intraarterial catheter angiography. The advantages of IV-DSA (with a peripheral injection technique) as compared to conventional angiography, include its non-invasive character, a lower complication rate and less discomfort for the patient. The disadvantages of IV-DSA include poorer image quality due to lower concentration of contrast media in the vessels, reduced spatial resolution and the need for larger volumes of contrast media. The indication for conventional angiography is an inconclusive intravenous study due to motion artifacts and/or poor resolution.

Analog-Digital Conversion↗
PubMed1987

[Distributed automatic control system for experiments on the cultivation of microorganisms].

Hard- and software of a distributed system for computer control of experiments on cultivation of microorganisms is described. The system is based on microprocessor techniques and minicomputer CM-4(1420). It provides intensification of microbiological studies due to rational management of experiments, accumulation and long-term storage of experimental data and their processing with specific algorithms for providing additional information on biosynthetic processes and optimization of fermentation conditions.

Analog-Digital Conversion↗
PubMed1987

[Computer-assisted system for interstitial hyperthermia].

The combination of interstitial radiotherapy and interstitial hyperthermia is more promising in the treatment of tumors than one of these methods alone. The unit developed by us uses the afterloading needles for heating up the tumor tissue with ohm current and for controlling the distribution of temperature in the target volume. Up to twelve needles are provided by one commutator with the R.F. current controlled by the computer. The temperature is measured by three thermistors per needle which are arranged at an axial distance of 2 cm each. The linearization of the thermistor characteristics and the control of cummutator and R.F. generator is performed by the computer over an interface constructed by us. In order to achieve a homogeneous distribution of temperature in the target volume and to avoid hot spots, we have examined several needle configurations by measuring in an homogeneous phantom.

Analog-Digital Conversion↗
PubMed1986

Pacemaker malfunction: fact or artifact?

In summary, the present examples illustrate how pacemaker malfunction can be simulated by the sources of artifact produced or detected by the monitoring equipment. This form of pseudopacemaker malfunction remains a common cause of mistaken diagnosis of pacemaker malfunction. A thorough understanding of the examples outlined above should help distinguish true pacemaker malfunction from pseudopacemaker malfunction produced by artifact.

Amplifiers, Electronic↗
PubMed1987

Power spectrum analysis in the study of ocular mechanisms.

The use of power-spectrum analysis in the study of ocular dynamics is becoming increasingly widespread. This paper summarizes the key points of signal acquisition and power-spectrum analysis, emphasizing aspects which we have found to be of relevance when the technique is applied to experiments in binocular accommodation. The considerations and conclusions are relevant to other areas of investigation into ocular dynamics and similar biological systems.

Accommodation, Ocular↗
PubMed1986

The effect of varying high pass filter parameters on the detectability of isolated pulmonary nodules in digitized chest images.

The effect of image processing of digital radiographic data on lesion detectability in clinical images has not been systematically studied. In this experiment, we evaluated a low frequency suppression filter program applied to CT digital radiographic localization images (General Electric Scoutview). Three different filter parameters affecting edge enhancement and local image contrast were applied to a set of digital chest images. A standard observer detection experiment comparing the variously filtered digital images and standard chest radiographs in the detection of lung nodules (11 peripheral lung fields, one superimposed on aortic arch) was performed. Standard chest radiography was more sensitive than the digital chest images, although some improvement was noted with increase in local image contrast and edge enhancement. Both image formats were equally specific. Image processing would be better evaluated using a digital imaging system with better performance parameters.

Analog-Digital Conversion↗
PubMed1986

[Analysis of the chromosome number in cells by flow cytometry].

A new flow-cytometric method is described that permits analysis of the number of chromosomes of individual cells. Preliminary stained mitotic cells are passed through a specially designed flow chamber in which they are destroyed just before passing through the focused laser beam of the flow cytometer. Signals from chromosomes of the destroyed cells are counted, and the results are represented as a distribution of the number of chromosomes in the cells. The method may be applied for the detection of relatively rare cells with abnormal numbers of chromosomes in biological and clinical research.

Analog-Digital Conversion↗
PubMedDate not supplied

[Simulator of cardiac activity signals].

Imitators of physiological signals are in need for production of electronic medical equipment and modeling the biological systems. The known imitators are rather intricate and incapable to control the output signal within a wide range. The imitator now offered allows to reproduce any signal that reflects the activity of a cardiovascular system under normal and pathologic conditions.

Analog-Digital Conversion↗