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PubMed1975

Design philosophy of air quality surveillance systems.

This paper discusses the design philosophy of the air quality surveillance systems which Kennecott is installing in the vicinity of its copper smelters in Arizona, Nevada, New Mexico, and Utah. These monitoring systems are part of supplementary control systems (SCS) that are utilized to ensure that short-term ambient air quality standards are met. These systems utilize minicomputers as remote terminals. The interface between a terminal and the primary sensors is via specially designed input/output circuitry. The system is controlled by a centralized host minicomputer, which is connected to each of the remote stations via a telephone line communication network. Real time data is displayed on cathode ray tubes located at strategic locations in the plants. This paper will discuss the system design philosophy from both a hardware and software point of view. The actual experience in design, development, and installation of the system will also be discussed.

Air Pollutants↗
PubMed1992

Variability of fixation disparity and accommodation when viewing a CRT visual display unit.

Fixation disparity and accommodation were measured while subjects viewed a target on a cathode ray tube at a 50 cm viewing distance. The psychophysical method of sequential testing was used. For measuring fixation disparity a series of brief dichoptic nonius targets was presented and the direction of perceived misalignment was reported by the subject. From these responses the psychometric function of fixation disparity can be derived which gives not only the mean fixation disparity but also the range of fluctuation during the period of measurement. During a 5 min period, this range was +/- 1.5 min arc averaged over subjects, when expressed as the range in which instantaneous fixation disparity fell with a probability of 68%. Repeated measurements on 5 days within 2 weeks gave a larger range of +/- 2 min arc. However, individual results can differ considerably from these average values. Repeated measurements and the analysis of the psychometric function can provide a more complete description of individual binocular status than is obtained with a single adjustment of continuously visible nonius targets. Laser optometry revealed that, compared to the stimulus distance of 50 cm, accommodation lagged behind in the range 1-2 D. The two display modes of bright characters on dark background and vice versa gave very similar results.

Accommodation, Ocular↗
PubMed1992

Comparison of 12-bit and 8-bit gray scale resolution in MR imaging of the CNS. An ROC analysis.

A reduction in gray scale resolution of digital images from 12 to 8 bits per pixel usually means halving the storage space needed for the images. Theoretically, important diagnostic information may be lost in the process. We compared the sensitivity and specificity achieved by 4 radiologists in reading laser-printed films of original 12-bit MR images and cathode ray tube displays of the same images which had been compressed to 8 bits per pixel using a specially developed computer program. Receiver operating characteristic (ROC) curves showed no significant differences between film reading and screen reading. A paired 2-tailed t-test, applied on the data for actually positive cases, showed that the combined, average performance of the reviewers was significantly better at screen reading than at film reading. No such differences were found for actually negative cases. Some individual differences were found, but it is concluded that gray scale resolution of MR images may be reduced from 12 to 8 bits per pixel without any significant reduction in diagnostic information.

Central Nervous System↗
PubMedDate not supplied

Hard-copy versus soft-copy image reading for detection of ureteral stones on abdominal radiography.

PURPOSE: The purpose of this study was to compare the usefulness of soft-copy images displayed on a cathode ray tube (CRT) with hard-copy images (film images) for detecting ureteral stones on abdominal radiography. MATERIALS AND METHODS: Five radiologists read images from 50 cases of ureteral stones and 50 normal cases diagnosed on the basis of intravenous urography and CT. For hard-copy reading, 10-bit images at 3,520x4,280 pixels obtained by computed radiography were printed on 14x17-inch films. For soft-copy reading, 8-bit images were displayed on a 17-inch monochrome monitor at 1,024x1,280 pixels. The study items were area under receiver operating characteristics (ROC) curve (Az), ureteral stone detection sensitivity and specificity, and reading time. RESULTS: For soft-copy and hard-copy images, the average Az values were 0.855 and 0.851, sensitivity was 62.8% and 62%, and specificity was 70.8% and 62.4%, respectively. There were no statistically significant differences between these values. Reading time was 106.6 min for soft-copy images, significantly longer than the 71.2 min for hard-copy images (p<0.05). CONCLUSION: Although soft-copy image reading time was longer than hard-copy image reading time, the ability to diagnose ureteral stones on abdominal radiography did not differ for soft- and hard-copy images.

Adolescent↗
PubMed2004

[Assessment of exposure to extremely low frequency magnetic field emitted from monitors].

OBJECTIVES: To investigate intensity of extremely low frequency magnetic field (ELFMF) emitted from cathode-ray tubes (CRT) of monitors in various directions and to find ways to avoid its influence. METHODS: Two hundred CRT monitors and 10 monitors with liquid-crystal display (LCD) were selected. Their ELFMF was detected for three times in front of the monitor at an interval of every 5 cm from 0 cm to 50 cm, as well as at various directions from the monitor. RESULTS: Intensity of ELFMF significantly attenuated at regular operating position (30 - 40 cm) from 0 cm to 50 cm in front of both 38 cm and 43 cm CRT monitors (P < 0.05). Intensity exceeded 0.4 microT both within 15 cm and 10 cm in front of 38 cm and 43 cm monitors. The highest intensity was found at the upright top position of both kinds of monitors, 9.54 microT for 38 cm monitor and 6.38 microT for 43 cm one, respectively. CONCLUSIONS: It is suggested to keep away from monitor screen as possible when operating a computer, to reduce unnecessary operation in front of a monitor screen, and to shorten operating time. To avoid more hazards from interactive interference between computers, it is necessary to increase distance between monitors.

Computers↗
PubMed1992

[Experimental study on possibility of corneal injury by electromagnetic wave].

The possibility of epithelial injury of BALB/C mice cornea exposed to a cathode ray tube (CRT) of a commercially available television was investigated. Epithelial injury of the cornea was confirmed by fluorescein-positive staining after 24 hours of CRT exposure approximately 3-9 cm from the surface of the CRT. The corneal epithelial injury was shown to be mainly limited to the most superficial layer by transmission electron microscope finding showing slight deterioration of the basal cell layer. The corneal epithelial defect was further measured by a scanning electron microscope in relation to the time of exposure to the CRT. The impaired area increased in dose-dependent manner to the some extent. The epithelial defect increased at 5 hours of CRT exposure and reached a maximum, that is 46.6% of the entire area of the cornea, by 12 hours of exposure, thereafter maintaining an equilibrium. The mechanism of corneal epithelial injury by CRT was discussed.

Animals↗
PubMedDate not supplied

Low-cost screening for microbial contaminants in aerosols generated in a dental office.

It has been reported that aerosols and droplets generated by high-speed dental drills and cavitrons are contaminated with blood and bacteria and represent a potential route for transmitting disease. Bacterial cells possess a negative electrical charge, while the cathode ray tubes (CRT) that are used in computer monitors generate positively charged static electric fields. Consequently, bacteria dispersed within these aerosols could be attracted to the screens on CRT monitors. In this study, pathogenic strains of Staphylococcus aureus were found on CRT screens in different locations within the Louisiana State University School of Dentistry facility. The results suggest that surveying CRT screens is a simple method for evaluating the airborne microbial contaminants present within a dental office.

Aerosols↗
PubMed2005

[Spectral colorimetric correction of full view color images in a real scene measurement system].

In the three dimensional multiple modalities scanning real scene measurement system, a color linear CCD was used to obtain the one dimensional linear color information of the scene. Successive one dimensional color images of different angles were patched to constitute the full view color image. If the color image is displayed directly on the color cathode ray tube (CRT) monitor of a computer, colorimetric distortion will occur. Colorimetric correction is then needed. Through thespectral colorimetric correction, the colorimage displayed on the color CRT monitor is matched with the original scene in the colorimetric sense.

Colorimetry↗
PubMed2006

Intra- and interobserver agreement and performance score of breast phantom image interpretation: influence of ambient room lighting levels.

The influence of ambient room lighting conditions on soft-copy breast phantom image interpretation was evaluated by comparing cathode ray tube (CRT) monitors with liquid crystal displays (LCDs). Nine observers were asked to use a three-point scale to rate the visibility of various phantom objects (masses, specks, and fibers) displayed on a 21-inch CRT (2,560 x 2,048) and a 21-inch LCD (2,560 x 2,048) under three different levels of ambient lighting (20, 100 and 420 lux at the display center). Each phantom image was interpreted twice, and the reproducibility of judgment and inter-observer agreement was evaluated using kappa statistics. Except for the "mass" score, the LCD score showed a significantly higher value (p<0.05) compared with that of CRT. Nevertheless, no significant differences were found among the three lighting levels. Furthermore, intra- and inter-observer agreement in judgments showed no effects of room illumination. Although the breast phantom objects were better visualized on LCDs than on CRT monitors, room illumination did not affect the performance score of soft-copy reading.

Breast Neoplasms↗
PubMed1991

Ponderable indices in the offspring and nucleic acids quantity in endocrine glands of rats exposed to real and sham VDU screens.

Adult female and male Imp: DAK rats were exposed beneath a real VDU screen (Erl groups) loaded with light-green characteristics due to computation of trigonometric functions in a loop program from a microcomputer. The control animals were exposed beneath a sham screen (Esh groups), being the front glass of vacuum devoid cathode ray tube covered with a transparent celluloid sheet printed with light-green characteristics. The difference in body weight of foetuses from autopsied Erl and Esh females was due mainly to a one-day delay in the fecundation of Esh females. In other groups of Erl females, a prolongation of the oestrous cycle was found in comparison to that of the Esh females. In both Erl females and Erl males, a nonsignificant decrease of weight of anterior pituitary and adrenals was found. RNA quantity was augmented in the anterior pituitary of Erl females and DNA quantity was diminished in the hypothalamus of Erl males. The obtained results suggest the suppression of hypothalamo-hypophyseal function in rats exposed to a real VDU screen.

Animals↗
PubMed1991

Effects of color CRT display on pupil size in color-blind subjects.

The effects of color cathode ray tube (CRT) display on the pupil size in color-blind subjects were studied experimentally. Red, magenta, green, cyan, yellow, and white were presented on the CRT. Five protan subjects, five deutans, and five normal subjects were tested using infrared pupillography. In the protan group, the pupils were significantly less sensitive to red (wavelength: 600 nm) targets compared to the other colors. In the deutans and the control group, there were non-significant changes in pupil size in response to the colors. Dominant wavelengths above 600 nm in color CRTs should be avoided in routine work presentation because of less sensitivity in protanopias.

Adult↗
PubMed1991

The effect of caffeine on the human macular circulation.

The acute effect of caffeine on the retinal circulation was studied in 14 healthy volunteers using the blue field simulation technique, which provides measurements of the velocity of leukocytes flowing within the macular capillaries. Subjects adjusted the mean velocity (Vm) of computer-simulated leukocytes moving on a cathode ray tube screen to match that of their own entoptically perceived leukocytes before and 1 hr after a double-masked, randomized administration of 200 mg caffeine or placebo. Caffeine produced an average 13% +/- 5% (SEM) decrease in Vm (P less than 0.05) and a 9% +/- 3% increase in diastolic blood pressure (P less than 0.05). The decrease in Vm and, presumably, blood flow occurring despite the increased diastolic blood pressure probably is attributable to retinal vasoconstriction. This effect may result from caffeine's known inhibitory effect on adenosine, a potent vasodilator of the retinal vasculature.

Adult↗
PubMed1977

Automated microdensitometry and quantification of lipoproteins by agarose gel electrophoresis.

A major obstacle in the application of quantitative microelectrophoresis has been tedious manipulations and calculations. To overcome these difficulties, we have developed an automatic system for the microdensitometry and calculations as part of a quantitative agarose gel electrophoresis facility. Results are internally standardized by serum cholesterol and/or triglyceride measurements. The hardware consists of a densitometer, an analog to digital converter, a cathode ray tube terminal, a teleprinter, and a small computer. A program in 4K words allows sample coding, electrophoretic scan display, indexing, and systematic identification of each peak. Data are acquired from scans of electrophoretic patterns of serum alone or in combination with the 1.006 gm/ml VLDL top and/or bottom preparative lipoprotein fractions. As many as 30 scans can be stored in 4K words of memory and then sent via high-speed telephone line to a larger computer for remote processing. The analysis corrects for baseline drifts and pre-beta asymmetry and will properly identify and quantify the amount of VLDL, LDL, and HDL with corrections for "sinking pre-beta" and "floating beta" in LDL and VLDL, respectively. Results are given in milligrams per 100 milliliter as well as percentile rank and standard deviation score ranking of each lipoprotein class as compared to an appropriate normal reference population. The latter data are in a form more meaningful to the physician and patient and provide a quantitative dimension to lipoprotein phenotyping.

Adult↗
PubMed1991

[Development of a new digital angiography system--improvement of rotational angiography and three dimensional image display].

The prototype of a rotational digital angiography system, has been improved to expand its range of application. The new system features an improved hardware configuration and new digital processing device. The system, called "computerized dynamic stereoradiography", is based on rapid transverse rotation of the X-ray apparatus, serial circumferential radiography and binocular stereographic imaging. The new digital processing device was included in the apparatus to provide rotational digital angiography. In use, mask exposures are first taken and all data are collected on a real-time basis into frame memories. Immediately afterwards, the X-ray apparatus is returned to the starting point and and live images are obtained. Subtraction images of all frames can be produced by a keyboard operation that requires less than 10 seconds. Three-dimensional images are rendered by two display systems with a 5 degree angle of difference. These images move at the same speed of rotation of two cathode ray tubes with 1,024 lines per screen, so that optical 3-D images can be observed. Digital angiography without subtraction is also available in the new system in both rotational and sequential modes. This is particularly useful when examining emergency patients and those who cannot hold their breath during X-ray exposure. This paper presents the principle and theory of the new system, and discusses its potential for overcoming the problems presented by current angiographic procedures in clinical practice.

Angiography, Digital Subtraction↗
PubMedDate not supplied

[The use of an echocardiograph and a rheoplethysmograph for computing the volume of the reverse blood flow in the atrioventricular heart valves].

The method of the combined use of the 2 series-produced outfits, an echocardiograph and an rheoplethysmograph, has been devised and tried on a clinical basis. The design parameters of the outfit make it possible to display the chest differential rheogram (DRG) obtained on an outfit on the screen of a cathode-ray tube. It is only one-stage recording of the echocardiogram of the right or (and) left ventricle and of the chest DRG that permits computing the volume of the reverse blood flow (regurgitation) in the atrioventricular valves of the heart. During separate use of these outfits, it is not feasible to measure the volume of regurgitation in the atrioventricular valves. The method suggested can be used for the design of an outfit with a broader range for studying heart anatomy and function.

Echocardiography↗
PubMed1989

[Experimental studies on the influence of astigmatism on eye accommodation].

We studied the influence of astigmatism on eye accommodation by means of a cathode ray tube (CRT) screen as a visual display terminal. Experiments using an infrared optometer and personal computer showed that artificial astigmatism over 1 diopter induced effects in the visual accommodation system of subjects in their twenties, decreasing the contraction velocity of accommodation, prolonging the settling time of accommodation and increasing the amplitude of accommodative fluctuation. Even if the visual acuity is fairly good with mild astigmatism, astigmatism need to be corrected for preservation of eye accommodation for VDT work in the young age group.

Accommodation, Ocular↗
PubMed1989

Simulator sickness in U.S. Navy flight simulators.

Flight simulators have become a major factor in pilot training. A general finding from Navy research on simulator design is that equipment features that offer faithful representation improve pilot performance and promote pilot acceptance. To the extent that an aircraft produces motion sickness, its simulator should induce the same result. However, reports of simulator sickness appear to be increasing and a shortcoming in simulation is implied when these effects occur in simulators during maneuvers that do not occasion them in the aircraft. This article presents incidence data from surveys of the 10 simulators at 6 different Naval/Marine Corps Air Stations. Approximately 1,200 simulator flights were recorded. Some severe motion sickness symptoms were recorded and some simulators induced unsteadiness afterwards. Individuals experiencing effects may be at risk if they drive themselves home or return to demanding activities at work. The simulators which exhibited the highest incidences of sickness were helicopter simulators with cathode ray tube (CRT) infinity optics and six-degrees-of-freedom moving base systems. Of those studied, fixed-wing, fixed-base, dome displays had relatively low incidence of simulator sickness.

Aircraft↗
PubMed1988

A new perimetric color vision analyzer.

A new apparatus was developed for mapping the extrafoveal color vision, the perimetric color vision analyzer. A yellow test object with varying degrees of saturation is presented on a cathode ray tube color display in a random sequence at one of 10 points around the fixation spot. The background is a mosaic pattern consisting of gray spots of the same size and shape as the test object, with various luminances. Background patterns with or without a test object are presented alternately. The subject is instructed to press a key when he detects a yellow object in the background pattern. The luminance of the test object is in the same range as the background gray spots. Since the luminance of background spots is changed synchronously at random when the test object appears, the subject can detect the test object only by the difference in color saturation. The results show the color contrast sensitivity at every designated point in the central visual field. The clinical application of the perimetric color vision analyzer revealed extrafoveal color defects which could not be evaluated with conventional color vision tests. It also showed that in some chorioretinal and optic nerve disorders the topographic pattern of color contrast sensitivity disagrees with that of luminance contrast sensitivity measured with automated static perimetry.

Adult↗