[Work conditions and prevention of occupational diseases of video display operators].
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Ocular tissue transparency is dependent on the regular lattice configuration of lens and corneal fibres of uniform diameter. Ageing is associated with degeneration of both lens and cornea, which lose some of their structural order and eventually their transparency, though this process is not uniform. The structural changes are local and result in ocular media opacities. When the opacities increase in number and extension, they begin to affect visual acuity. As the loss of acuity becomes clinically significant, we speak of clinically relevant cataract. Retinal exposure to light diffused by intraocular light scattering induces optical glare, one of two forms of glare. The other form is transient glare--i.e., glare due to adaptation problems in an environment with rapidly changing ambient luminance. Contemporary society is characterised by increasing emphasis on visual information in such forms as texts, icons, signs and symbols. The computer revolution has been accompanied by further stress on the importance of the detection and interpretation of written instructions.
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Psychophysiologic studies covered 10th grade pupils with normal and short sight, who worked at IBM PS/2(VGA) during summer. If compared to normal-sighted ones, the shortsighted pupils demonstrated drastic functional changes. The studies set optimal duration of work at the PS-2 hours or no more than 3 hours with obligatory prophylaxis.
Ergonomics is an increasing health concern for all work environments in the 1990s. Ergonomic stresses do exist in the dental office for all personnel, and proposed regulatory activity will include dentistry. Hopefully, the pace of regulation will be met by scientific investigation that quantifies these stresses and defines their proper management and prevention. If so, ergonomics will become well-understood and will not develop as a new frontier of misapplied regulation.
This study investigates electrostatic fields surrounding the human head and particle deposition onto facial skin and eyes caused by the combined effect of electrostatic and wind fields. The electrostatic fields are calculated by a three-dimensional numerical model calculating the field strength between a field source and a human head. The deposition velocity can be viewed as determined by the sum of two contributions: that of an electrostatic field and that of a wind field. Deposition velocities are calculated by a semiempirical particle deposition model that considers particle transport from the free stream to the human face. The particle deposition model uses the electrostatic field model results as input parameters and is applied to the forehead and eyes of two facial shapes for two different turbulence conditions and aerosol charge distributions. The results of different practical working conditions, under which the potential difference between head (person) and source ranges from 5.6 to 15.0 kV, indicates that the presence of electrostatic fields always increases particle deposition for industrial aerosols. For aged aerosols an effect is only present for submicron particles.
Since the results of a preliminary study have shown that the magnetic fields of some visual display units (VDUs) increased the release of mercury from amalgam specimens, the aim of the present study was to examine whether exposure to magnetic fields might affect the mercury vapor release from amalgam restorations in humans. The test group consisted of five subjects with an average of 31.4 amalgam surfaces (range 13-48). In each of the subjects tested, the intra-oral release of mercury vapor was measured during three 9-h periods at intervals of 30 to 90 min, using a standardized schedule and standardized food. During the first 9-h period which served as control, no intentional magnetic fields were applied. During the second and the third 9-h period, magnetic fields with flux densities of 20 microT at 30 kHz or 500 microT at 50 Hz, respectively, were applied. Although these flux densities were one thousand times higher than those caused by VDUs, no effects could be found on the release of mercury vapor from the amalgam restorations. The results of the present study do not support the assumption that exposure to magnetic fields increases the mercury vapor release from amalgam restorations in humans.
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Computed radiology is a radiographic imaging technology that generates a conventional radiographic image in digital form. The image can be recorded on a laser sensitive film or archived to a digital storage device and displayed on a video monitor. This study was performed to evaluate the adequacy of reporting digitised images directly from the workstation. The test set consisted of portable chest images of 55 patients from the cardiothoracic intensive care unit. Normal structures and nine abnormalities were pre-selected for analysis. The radiographs and images on the video display were reviewed on two separate occasions, six months apart by two independent readers. No clinical details were supplied and the intraobserver and interobserver agreement were assessed using Kappa statistics. The overall results indicated that direct reporting from the workstation was as reliable as reporting from the laser printed copies.
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The purpose of this study was to reveal the optimum size and inter-key spacing of numeric square keys for touch screens. Six male students (22-25 years old) and three female students (21-24 years old) volunteered as subjects for this experiment. Each subject took part in data entry tasks using numeric square keys of touch devices. The sizes of keys were 6, 12, 21, 30 and 39 mm and each the inter-key spacing was 0, 3, 6, 12 and 21 mm. Response times with key sizes of 6 and 12 mm were significantly slower than with key sizes of 21 and 30 mm (p < 0.001). Furthermore, the key size of 6 mm significantly caused more errors than the key sizes of 12, 21, 30 and 39 mm (p < 0.05). The response time with inter-key spacing of 3 mm was significantly faster than with that of 0, 6, 12 and 21 mm (p < 0.001). Inter-key spacing of 0 mm significantly produced more errors than other inter-key spacing. Subjective ratings for inter-key spacing of 3, 6 and 12 mm were significantly better than those of 0 and 21 mm (p < 0.05). These results suggested that the optimum size of numeric square keys for touch screens should be more than 21 mm and optimum inter-key spacing should be from 3 to 6 mm. Optimum key size, however, must be selected with regard to the limitation of screen size.
Sixty full-time VDU workers participated in a field study concerned with the effects of antiglare screen filter on the occurrence, duration, and intensity of eye and physical complaints. Forty of them were given a screen filter, the remaining 20 worked without filter. Two types of questionnaires were administered both prior to the installation of filters, and after one month of their use. The first inquired about the occurrence and duration of complaints during the last month, the other one measured their intensity on three days in the morning, before lunch and at the end of the working day. The intensity scores were corrected for hours worked at VDU on the day concerned. The filter and control group did not differ in age, gender, years of work experience at VDU, type of work task, self-reported overall health, eye conditions, and ergonomic layout of the workstation. The differences between the initial and final measurement were processed for each group separately by applying t-tests for paired samples, and both groups were compared by an analysis-of-variance test. Whereas the control group did not show any significant change, the participants in filter group reported less occurrence, shorter duration, and less intensive eye and musculoskeletal complaints after one month of filter use. It may be concluded that screen filters improve the conditions for the visual perception of the VDU, thus relieving eye strain, and that they positively influence the working posture and help relieve musculoskeletal complaints as well.
OBJECTIVES: This study assessed work postures, movements, psychosocial job demands, and shoulder and wrist extensor muscle activity and registered the prevalence of musculoskeletal symptoms of computer-aided design (CAD) operators. METHODS: A questionnaire survey was used to study the use of the computer mouse, psychosocial work factors, and musculoskeletal symptoms among 149 CAD operators. A workplace study was performed using observations, electrogoniometers on the wrists, and electromyography to measure exposures and physiological responses during CAD work among a subgroup of the CAD operators. RESULTS: Musculoskeletal symptoms were far more prevalent for the arm or hand operating the mouse than for the other arm or hand, and women were more affected than men. The symptoms may be related to such risk factors as repetitive movements, static postures (eg, ulnar-deviated and extended wrist on the mouse side), and static muscular activation patterns. The risk factors were present due to continuous mouse use and possibly also due to high demands for mental attentiveness, precision, and information processing. CONCLUSIONS: Exposure during work with a computer mouse may present a risk for developing musculoskeletal symptoms. Improvements should focus on introducing more variation.
In addition to physiologic differences between men and women, differences in pain reporting and medical care-seeking behavior, job assignments and ergonomic exposures (including work in the home), and strategies for performing various physical tasks must be considered.
Computer video display terminals have revolutionized the home and office work habits of millions of people. Although no verifiable organic ocular diseases have been shown to derive from computer monitors, symptoms related to eyestrain are very common. Some 10% to 15% of patients presenting for routine eye exams complain of computer-related headache and eyestrain. Comprehensive ocular examination including distance, intermediate and near refraction, as well as uncovering evidence of ergonomic and lighting inadequacy, often is clinically quite helpful. A careful eye exam with particular attention to middle and near range refraction, oculomotor balance, the workstation, lighting, and seating comfort will assist measurably in alleviating eyestrain.
The initial impact of computer assisted preventive screening in general practice consultations has been monitored. The technology has not been found stressful by patients, and the power of the consultation to alleviate low arousal has been increased by computer use. No appreciable increase in the durations of consultation was detected, despite an average computer initiated input of two minutes eight seconds. The computer has successfully prompted preventive screening and health education with a sixfold increase in the number of potentially relevant procedures being mentioned. The actual information presented by the computer has been shown to be crucial, with the terminal's mere presence an ineffective reminder. The computer terminal was used in 65% of the consultations for which it was available, which, if sustained, represents an effective screening programme for attending patients.
The Bunyaviridae family of enveloped RNA viruses includes five genuses, orthobunyaviruses, hantaviruses, phleboviruses, nairoviruses and tospoviruses. It has not been determined which Bunyavirus protein mediates virion:cell membrane fusion. Class II viral fusion proteins (beta-penetrenes), encoded by members of the Alphaviridae and Flaviviridae, are comprised of three antiparallel beta sheet domains with an internal fusion peptide located at the end of domain II. Proteomics computational analyses indicate that the carboxyl terminal glycoprotein (Gc) encoded by Sandfly fever virus (SAN), a phlebovirus, has a significant amino acid sequence similarity with envelope protein 1 (E1), the class II fusion protein of Sindbis virus (SIN), an Alphavirus. Similar sequences and common structural/functional motifs, including domains with a high propensity to interface with bilayer membranes, are located collinearly in SAN Gc and SIN E1. Gc encoded by members of each Bunyavirus genus share several sequence and structural motifs. These results suggest that Gc of Bunyaviridae, and similar proteins of Tenuiviruses and a group of Caenorhabditis elegans retroviruses, are class II viral fusion proteins. Comparisons of divergent viral fusion proteins can reveal features essential for virion:cell fusion, and suggest drug and vaccine strategies.