Accommodation to simulations of defocus and chromatic aberration in the presence of chromatic misalignment.
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Previous studies have demonstrated that accommodation will respond to sine gratings in which the relative modulations of red, green and blue image components have been altered to simulate the effects of defocus and longitudinal chromatic aberration. The present study aimed to determine the tolerance of the accommodative system to relative phase shifts in those components induced by chromatic misalignment. It was found that accommodation can tolerate moderate amounts of chromatic misalignment (6'), but responds adversely when misalignments are large. Applications to visual display terminals and spectacle lens and instrument design are discussed. (+info)
Medical and social prognosis for patients with perceived hypersensitivity to electricity and skin symptoms related to the use of visual display terminals.
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OBJECTIVES: This study attempted to give a medical and social prognosis for patients with perceived "electrical sensitivity". METHODS: In 1980-1998, 350 patients with electrical sensitivity were registered at the University Hospital of Northern Sweden in Umea, Sweden. Those with hypersensitivity to electricity had multiple symptoms evoked by exposure to different electric environments. Those with skin symptoms related to the use of visual display terminals (VDT) predominantly had facial skin symptoms evoked by a VDT, television screens, or fluorescent light tubes. A questionnaire on civil status, current health status, care, treatment and other measures taken, consequences of the problem, eliciting factors, and current employment was sent to all the patients. The response rate was 73%. Of the 50 respondents with hypersensitivity to electricity, 38% were men and 62% were women. Of the 200 patients with skin symptoms related to VDT use, 21.5% were men and 78.5% women. RESULTS: More women than men had turned to caregivers, including complementary therapies. A larger proportion of patients with hypersensitivity to electricity (38%) than those with skin symptoms related to VDT use (17%) was no longer gainfully employed. Both groups reported a higher symptom frequency than that reported by the the general population. Over time, the medical prognosis improved in the latter group but not in the former. CONCLUSIONS: Patients with hypersensitivity to electricity, particularly women, have extensive medical problems and a considerable number of them stop working. Many patients with skin symptoms related to VDT use have a favorable prognosis. Both groups need early and consistent management. (+info)
Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness.
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The effects of performing video display terminal (VDT) tasks with a bright display (BD) at night on nocturnal salivary melatonin concentration, rectal temperature, heart rate, and sleepiness were examined. Seven healthy male adults performed exciting VDT tasks with a BD and a dark display (DD) and boring VDT tasks with a BD and a DD from 2300 to 0200. The light intensities of the BD and DD were 45 and 15 lx at each subject's eye level, respectively. The exciting VDT task with both BD and DD significantly suppressed the nocturnal decrease in rectal temperature and heart rate and the nocturnal increase in sleepiness. The BD significantly suppressed the nocturnal decrease in rectal temperature during both exciting and boring VDT tasks. The nocturnal salivary melatonin concentration was significantly suppressed by the combination of the exciting task and BD. The results suggest that performing an exciting VDT task with a BD suppresses the nocturnal changes in melatonin concentration and other physiological indicators of human biological clocks. (+info)
ISABEL: a web-based differential diagnostic aid for paediatrics: results from an initial performance evaluation.
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AIMS: To test the clinical accuracy of a web based differential diagnostic tool (ISABEL) for a set of case histories collected during a two stage evaluation. METHODS: SETTING: acute paediatric units in two teaching and two district general hospitals in the southeast of England. MATERIALS: sets of summary clinical features from both stages, and the diagnoses expected for these features from stage I (hypothetical cases provided by participating clinicians in August 2000) and final diagnoses for cases in stage II (children presenting to participating acute paediatric units between October and December 2000). MAIN OUTCOME MEASURE: presence of the expected or final diagnosis in the ISABEL output list. RESULTS: A total of 99 hypothetical cases from stage I and 100 real life cases from stage II were included in the study. Cases from stage II covered a range of paediatric specialties (n = 14) and final diagnoses (n = 55). ISABEL displayed the diagnosis expected by the clinician in 90/99 hypothetical cases (91%). In stage II evaluation, ISABEL displayed the final diagnosis in 83/87 real cases (95%). CONCLUSION: ISABEL showed acceptable clinical accuracy in producing the final diagnosis for a variety of real as well as hypothetical case scenarios. (+info)
Effects of software programs stimulating regular breaks and exercises on work-related neck and upper-limb disorders.
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OBJECTIVES: This study evaluated the effects on work-related neck and upper-limb disorders among computer workers stimulated (by a software program) to take regular breaks and perform physical exercises. Possible effects on sick leave and productivity were studied as well. A randomized controlled design was used with cluster randomization. Altogether 268 computer workers with complaints in the neck or an upper limb from 22 office locations were randomized into a control group, one intervention group stimulated to take extra breaks and one intervention group stimulated to perform exercises during the extra breaks during an 8-weekperiod. Questionnaires were administered before andafter the intervention, and questions were generated by the software during the intervention period. Computer usage was recorded online. RESULTS: The data on self-reported recovery suggested a favorable effect; more subjects in the intervention groups than in the control group reported recovery (55% versus 34%) from their complaints and fewer reported deterioration (4% versus 20%). However, a comparison between the reported pre- and postintervention scores on the severity and frequency of the complaints showed no significant differences in the change among the three groups. No effects on sick leave were observed. The subjects in the intervention groups showed higher productivity. CONCLUSIONS: The use of a software program stimulating workers to take regular breaks contributes to perceived recovery from neck or upper-limb complaints. There seems to be no additional effects from performing physical exercises during these breaks. (+info)
DNA microarray data and contextual analysis of correlation graphs.
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BACKGROUND: DNA microarrays are used to produce large sets of expression measurements from which specific biological information is sought. Their analysis requires efficient and reliable algorithms for dimensional reduction, classification and annotation. RESULTS: We study networks of co-expressed genes obtained from DNA microarray experiments. The mathematical concept of curvature on graphs is used to group genes or samples into clusters to which relevant gene or sample annotations are automatically assigned. Application to publicly available yeast and human lymphoma data demonstrates the reliability of the method in spite of its simplicity, especially with respect to the small number of parameters involved. CONCLUSIONS: We provide a method for automatically determining relevant gene clusters among the many genes monitored with microarrays. The automatic annotations and the graphical interface improve the readability of the data. A C++ implementation, called Trixy, is available from http://tagc.univ-mrs.fr/bioinformatics/trixy.html. (+info)
Work related and individual predictors for incident neck pain among office employees working with video display units.
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AIMS: To investigate work related and individual factors as predictors for incident neck pain among office employees working with video display units (VDUs). METHODS: Employees in three administrative units of a medium sized city in Finland (n = 515) received mailed questionnaires in the baseline survey in 1998 and in the follow up survey in 1999. Response rate for the baseline was 81% (n = 416); respondents who reported neck pain for less than eight days during the preceding 12 months were included into the study cohort as healthy subjects (n = 232). The follow up questionnaire 12 months later was completed by 78% (n = 180). Incident neck cases were those reporting neck pain for at least eight days during the preceding 12 months. RESULTS: The annual incidence of neck pain was 34.4% (95% CI 25.5 to 41.3). Poor physical work environment and poor placement of the keyboard increased the risk of neck pain. Among the individual factors, female sex was a strong predictor. Smoking showed a tendency for an increased risk of neck pain. There was an interaction between mental stress and physical exercise, those with higher mental stress and less physical exercise having especially high risk. CONCLUSION: In the prevention of neck disorders in office work with a high frequency of VDU tasks, attention should be given to the work environment in general and to the more specific aspects of VDU workstation layout. Physical exercise may prevent neck disorders among sedentary employees. (+info)
Workstation scheme and implementation for a medical imaging information system.
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OBJECTIVE: To discuss the scheme and implementation of workstation configuration for medical imaging information systems suitable to the practical situation in China. METHODS: The workstations were logically divided into picture archiving and communication system (PACS) workstations and radiology information system (RIS) workstations. The former applied to three kinds of diagnostic practice: the small matrix images, large matrix images and high resolution grayscale display applications. The latter consisted many different models defined by the usage and function processes. RESULTS: A dual-screen configuration for image interpretation workstations integrated the image-viewing and reporting procedures physically. Small matrix images as CT or MR were operated on 17 inch (1 inch = 2.54 cm) color monitors, while conventional X-ray interpretation was performed on 21 inch color monitors or portrait format grayscale 2 k by 2.5 k monitors. All other RIS workstations not involved in imaging process were set up with a common PC configuration. CONCLUSION: Workstation schemes for medical imaging information systems should satisfy the basic requirements of medical imaging and investment budget. (+info)