An experimental study of work load on VDT performance. Part 2. Effects of difference in input devices

Effects of the difference in input device on work load of VDT task were studied. The subjects of the experiment were eight healthy male college students (age: 21-22 yr) having a binocular vision of not less than 0.7 and no astigmatism or hyperopia. The test consisted of an experimental word processing task in which the subjects visually searched e's in given sequences of alphabetical letters displayed on the CRT and converted them to 5's through input device operation. As for experimental conditions, two kinds of input devices, namely, keyboard and lightpen were adopted and 1 h was provided as each operation time. Critical flicker fusion (CFF), near point distance, accommodation time, subjective fatigue symptoms, blinking counts, pupillary reflex, electromyogram in upper limb, neck and shoulder and performance score were measured. The results were as follows. Decrease in C.F.F. was observed in two experimental conditions during the process of operating time. Increments in complaints of subjective fatigue related to visual function were seen in the two experimental conditions after 1 h VDT task. A higher error rate in performance was observed in the subjects using the lightpen compared to the one using the keyboard. The frequency of both blinking and pupil-size changes were lower in the subjects using the lightpen compared to those using the keyboard. This suggests that the gaze time of the VDT screen with lightpen-condition is longer than that in keyboard-condition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Central nervous system effects and visual fatigue in VDT workers

Summary To assess central nervous system effects and visual fatigue induced by work with visual display terminals (VDT), symptom frequency was assessed and visual evoked potential (VEP), critical flicker fusion (CFF) and near-point distance were measured in 24 female keypunchers before and after 2.5 h of VDT work and in 6 non-VDT-exposed subjects at the same intervals. Each keypuncher had been engaged in data entry for 1–7 (mean, 4) years. After VDT work, the number of complaints of subjective fatigue as well as an objective measure of near-point distance were significantly increased as compared with those before work; also, the N75, P100 and N145 latencies of VEP were significantly prolonged. The change of P100 latency during VDT work was inversely correlated with the number of years worked in data entry. No significant change was seen in any of these tests in the non-VDT-exposed subjects. The changes in N75 latency and subjective fatigue related to drowsiness and dullness in the keypunchers were significantly larger than those in the non-VDT-exposed subjects. The CFF was significantly lower in keypunchers than in non-VDT-exposed subjects in both the first and the second tests. These data suggest that VDT work is associated with impairment of the visual nervous system function, that VEP latencies appear to be a sensitive indicator of visual fatigue, at least transiently, and that CFF appears to be a good parameter for estimations of chronic visual fatigue.     

上海市饮水机污染状况及其影响因素分析

[目的]通过对普通饮水机和冰水机污染状况的调查及其影响因素的分析,对饮水机微生物污染的情况作出一个初步的评价,以便为将来改进和提高饮水机的卫生性能提供科学依据。[方法]随机选择188台普通饮水机和16台冰水机进行卫生学调查,分析调查因素与检出微生物指标之间的关系。[结果]普通饮水机常温龙头水细菌总数、总大肠菌群超标率分别为70.2%、11.2%,霉菌检出率为41.5%;冰水机低温龙头水细菌总数、总大肠菌群超标率分别为81.3%、12.5%,未检出霉菌。饮水机聪明座的霉菌污染与桶内水霉菌污染之间(r_s=0.427,P=0.007)、聪明座的霉菌污染与常温龙头水之间(r_s=0.464,P=0.003)存在等级相关关系。不同放置场所的饮水机常温龙头水总大肠菌群的检出率不同(x~2=14.669,P=0.047);饮水机上使用水的种类对常温龙头水霉菌的检出率有影响(x~2=16.441,P=0.001);桶装水的周转时间及饮水机的清洗频率对常温龙头水总大肠菌群的检出率有影响(分别为x~2=8.254,P=0.041和x~2= 11.348,P=0.010)。[结论]必须重视饮水机的微生物污染;改造饮水机的现有结构;加快桶装水的周转时间并增加清洗频率,正确清洗。     

Variations of physiological functions and psychological measures and their relationships on delayed shift of sleeping time

The variations of sublingual temperature, pulse rate, flicker fusion frequency (CFF), subjective fatigue feelings (SFF) and 8 selected reaction times and the relationships between them were examined in six university students under the condition of successive 6-h delayed shift with 8 sleeping h and 22 waking h for 6 d. SFF was measured by the scales proposed by the Japanese Society for Industrial Fatigue Research. On the 2nd d when the shifting was started after the subjects had slept from 00:00 to 08:00 and on the 3rd d after sleeping h of 06:00 to 14:00, the variations of sublingual temperature, pulse rate and CFF showed a pattern of circadian rhythm. However, on the 4th-5th d the rhythms of sublingual temperature and pulse rate were flattened. On the other hand, CFF demonstrated a variation of having a nearly constant tendency till 08:00, followed by a gradual decrease during the daytime. The variation of SFF (the scale of "sleepiness and dullness") was similar to that of CFF, although the change of the score was in the opposite direction. On the 3rd-4th d, the 4th-5th d and the 6th d, significantly high rank correlations were observed between sublingual temperature and pulse rate and between CFF and SFF. However, between sublingual temperature and CFF, a high correlation which was observed on the 1st and the 2nd d was not seen on the 4th-5th and 6th d. Eight selected reaction times were shortened during the experimental days, but there was no consistent pattern of variation within these days. The results of the experiment showed that the relationship between CFF and SFF exists during the daytime when the arousal level is low.     

An experimental study on the duration of a single spell of work on VDT (visual display terminal) performance

The relation between work load and the duration of a single spell of work on VDT performance studied in an experimental word processing task. Nine healthy male college students performed 2-hour visual tasks under the following three sets of work conditions. In the first set, subjects performed VDT work for two hours without intermission. In the second set, subjects had a 10-minute intermission after a 1-hour task. In the third set, there was a 5-minute intermission after a 30-minute task. Critical flicker fusion, near point distance, subjective fatigue symptoms, heart rate, respiratory rate, blinking counts, electromyogram in upper limb and performance score were measured. Results are as follows. Decrease in critical flicker fusion, increase in near point distance and subjective fatigue symptoms appeared in all three sets of experimental conditions after two hour tasks. Increased slow wave components on electromyogram and increased errors in performance appeared after 60-minute or more tasks without intermission. Effects on the critical flicker fusion, near point distance, subjective fatigue symptoms, electromyogram, blinking counts and errors in performance were least in the third set. The results of this study suggest that in order to reduce operators' fatigue on VDT work of the conversation type, countermeasures such as shortening the duration of a single spell of work to less than 60 minutes and taking frequent short intermission are necessary.     

Effects of VDT workstation lighting conditions on operator visual workload

Industrial lighting covers a wide range of different characteristics of working interiors and work tasks. This study investigated the effects of illumination on visual workload in visual display terminal (VDT) workstation. Ten college students (5 males and 5 females) were recruited as participants to perform VDT signal detection tasks. A randomized block design was utilized with four light colors (red, blue, green and white), two ambient illumination levels (20 lux and 340 lux), with the subject as the block. The dependent variables were the change of critical fusion frequency (CFF), visual acuity, reaction time of targets detection, error rates, and rating scores in a subjective questionnaire. The study results showed that both visual acuity and the subjective visual fatigue were significantly affected by the color of light. The illumination had significant effect on CFF threshold change and reaction time. Subjects prefer to perform VDT task under blue and white lights than green and red. Based on these findings, the study discusses and suggests ways of color lighting and ambient illumination to promote operators' visual performance and prevent visual fatigue effectively.     

Measurements of occupational exposure for a technologist performing 18F FDG PET scans

Radiation doses to one PET technologist performing 100 18F FDG (18F fluorodeoxyglucose) imaging procedures were measured in a clinical setting using two types of thermoluminescent dosimeter (TLD) badges, one finger-ring TLD and one electronic pocket dosimeter (EPD). 18F FDG was handled either with unshielded or with viewing window tungsten shielded syringes. The resulting doses using unshielded syringes were 13.8 +/- 0.8 microSv/370 MBq and 14.3 +/- 0.4 microSv/370 MBq, measured with TLD 100 and with TLD 700H/600H, respectively. For the same series of measurements, the doses obtained using shielded syringes were 10.7 +/- 0.4 microSv/370 MBq and 7.2 +/- 2.1 microSv/370 MBq with TLD700H/600H and with EPD, respectively. The dose to the right hand from shielded syringes was 69.3 +/- 5.5 microSv/370 MBq. All these values are within the ICRP recommended dose limits. Extrapolated to 725 examinations per year, the resulting effective dose measured with TLD would be 10 mSv with unshielded and 7.5 mSv with shielded syringes, respectively (25% dose reduction). The doses measured by TLD were consistently higher than those measured by EPD, suggesting that EPD measurements might underestimate occupational doses.     

Effects of video games on visual function in children

Health effects of video games were examined with a questionnaire survey and an experimental study. In the survey, age, sex, playing time with video games in a day, viewing distance between the eyes and the television screen, subjective symptoms of eye strain, and changes of visual acuity were investigated in 2,034 male and 2,321 female primary school children. In the experimental study, the visual loads of a one-hour word processing task and a video game were compared with various indices, such as critical flicker fusion, near point distance, blinking counts, eyeball movement, pupillary reflex and subjective fatigue symptoms in ten healthy male college students. The results of this study were as follows: 1) The viewing distance between the eyes and the TV screen was shorter for video games than for watching TV programs. 2) The rate of complaints related to eye strain in children who played video games over 120 min per day was significantly higher than that of other children. 3) The eye movements during video games were more rapid and frequent than those during conventional VDT work. 4) A decrease in CFF value and an extension of near point distance and an increase in subjective fatigue symptoms were demonstrated for both the word processing task and the video game. No significant differences were observed between the above two experimental conditions. This suggests that the visual loads for video games are similar to those for VDT work. These findings suggest that regulating the playing times to 60 minutes or less per day is necessary to prevent negative health effects in children.     

视屏显示终端视觉疲劳对脉搏信号的影响

目的通过对脉搏信号特征的提取与分析,寻找诊断与评测VDT视觉疲劳状态的客观指标。方法由问卷调查表选定37例健康被试者,设计视觉疲劳实验。在VDT实验前后,分别采集被试者光电脉搏信号,并对被试者进行疲劳症状问卷调查和闪光融合频率计测定以及体温测量。对脉搏信号进行时域和频域分析,提取波形高度和功率谱峰值作为特征参量。结果通过对疲劳症状问卷的统计分析发现,以Rechichi提出的判断标准,视疲劳实验后,被试者均处于视疲劳状态。闪光融合频率值下降显著(P<0.05),同时体温下降显著(P<0.01)。视疲劳后脉搏信号的波形高度和功率谱峰值均显著降低(P<0.001)。结论脉搏信号的波形高度和功率谱峰值能够较客观地反映人体VDT视疲劳状态,有望作为视疲劳状态诊断与评测的客观指标。     

An experimental study of work load on VDT performance. Part 1. Effects of polarity of screen and color of display

Study were made on the effects of polarity of screen and color of display on work load of VDT tasks. The subjects of the present experiment were eight healthy male college students (age: 21-23 yr) having a naked binocular vision of not less than 0.7 and no astigmatism nor hyperopia. The test consisted of an experimental word processing task in which the subjects visually searched e's in given sequences of alphabetical letters displayed on the CRT and converted them to 5's through keyboard operation. As for experimental conditions, four levels of screen image, that is, positive and negative screens and green and white colored displays were adopted and 2 hr were given for each operation time. Critical flicker fusion (CFF), near point distance, accommodation time, subjective fatigue symptoms, heart rate, electromyogram in upper limbs and performance score were measured. The following results were obtained. Decrease in C.F.F. and extension of near point distance were observed in all experimental conditions during the operating time. Increase in complaints of subjective fatigue related to visual function was observed in all experimental conditions after two hour VDT task. Greater extension of near point distance and larger complaints of subjective fatigue were observed in subjects using the green colored display than in those using the white colored display. This suggests that the visual load using the green colored display is larger than that using the white colored display. A larger decreased in C.F.F. and greater complaints of subjective fatigue were demonstrated in subjects using negative screen than those using positive screen. This suggests that the visual load using the negative screen is larger than that using the positive screen.     

A device for the automatic measurement of blood pressure in epidemiologic studies

An automatic blood pressure apparatus was devised for use in an epidemiological study that required self-administered measurements of blood pressure for up to 200 students each week over a school year. A Dinamap device was used to determine systolic and diastolic blood pressures by the oscillometric method. An Apple II Plus computer with one disc drive was used for control of the device and storage of data. Two such apparatuses were assembled and used to make more than 6,000 recordings of blood pressure over a six-month period. Except for some initial problems with a computer component, the apparatuses performed well; successful blood pressure recordings were obtained 99% of the time. Use of the automatic devices proved to be very acceptable to students. It is concluded that the use of such devices offers a reasonable means for obtaining accurate measurements of blood pressure and may be applicable for many epidemiologic studies.     

高速铁路司机作业前后疲劳状况调查分析

目的了解高速动车组司机作业前后疲劳状况。方法采用现场测试及疲劳指标评估表调查高速动车组司机的主客观疲劳状况并与既有线动车组司机进行比较。结果京津城际高速动车组司机作业前后闪光融合频率测试疲劳状况不明显,而既有线动车组司机却有统计学差异;疲劳指标评估表经疲劳类型除权后高速动车组司机的疲劳类型按疲劳程度由高到低排序为整体身心疲劳、脑力疲劳、心理疲劳、眼疲劳及体力疲劳,退乘后与出乘前的疲劳程度表现相吻合:既有线动车组司机退乘后的疲劳类型按疲劳程度由高到低排序为心理疲劳、整体身心疲劳、脑力疲劳、眼疲劳及体力疲劳。结论应根据动车组司机的作业特点,重点关注动车组司机的心理疲劳状况。     

姜黄素对肺纤维化大鼠肺组织TGF—β1与HGF表达的影响

目的探讨TGF—β1与HGF在肺纤维化中的作用及不同浓度姜黄素对博莱霉素诱导的肺纤维化大鼠肺组织中HGF及TGF—β1表达的影响。方法健康雄性SD大鼠90只,随机分为6组。分别为空白对照组（A组）、模型组（B组）、泼尼松治疗组（C组）、姜黄素50组（D组）、姜黄素100组（E组）、姜黄素200组（F组）,应用气管内给予博莱霉素制作肺纤维化动物模型。造模7、14、28d时分三次取材。用RT-PCR,Western blot检测各组肺组织中HGF及TGF—β1 mRNA及蛋白的表达。结果A组28dTGF—β1的光密度值（0．693±0．028）及灰度值（0．96±0．10）最低。B组28dTGF—β1光密度值（1．586±0．020）及灰度值（1．77±0．15）最高、F组28dTGF—β1光密度值（0．881±0．032）及灰度值（1．19±0．12）与B组比较最低。而HGF的光密度值及灰度值的检测正好相反。F组28dHGF的光密度值及灰度值最高。B组与D组的HGF和TGF—β1光密度值及灰度值差异无统计学意义（P〉0．05）。结论姜黄素抑制肺纤维化的机制之一可通过增高HGF的活性同时减低TGF—β1的活性来实现,这种作用有一定的剂量依赖性。     

高胆红素血症与新生儿自发性眨眼的关系研究

目的评估高胆红素血症对新生儿自发性眨眼的影响。方法采用新生儿行为神经(NBNA)评分法、5分钟眨眼试验,检测评估53例高胆红素血症新生儿,按小时胆红素值分为高胆1组(小时胆红素第75百分位值)和高胆2组(小时胆红素第95百分位值),在黄疸消退后重复上述两项测评,并与38例同日龄正常新生儿对照。结果 (1)高胆红素血症新生儿NBNA评分明显低于正常同日龄新生儿,且自发性眨眼明显增多,差异有统计学意义(P0.05)。(2)高胆红素血症新生儿在黄疸消退后,NBNA评分和自发性眨眼频率较黄疸高峰期有所恢复,结果差异有统计学意义(P0.01)。(3)黄疸消退后高胆1组与同日龄的正常新生儿比较,NBNA评分和5分钟自发性眨眼频率差异无统计学意义(P值均0.05)。而高胆2组NBNA总分包括原始反射、一般评估仍明显低于正常同龄新生儿(P0.01);自发性眨眼频率仍较同日龄新生儿增多(P0.05)。(4)黄疸消退后高胆1组的NBNA评分、自发性眨眼恢复较好,与高胆2组比较差异有统计学意义(P0.05)。结论高胆红素血症可影响新生儿的行为表现和自发性眨眼频率,其影响程度与黄疸严重度有关。     

眨眼频率-反映急性刺激作用的生物标志

目的 :探讨用眨眼频率代替眼刺激感觉强度 ,作为反映气态甲醛对人体眼部刺激作用的生物标志。方法 :采用控制暴露人体实验。通过对 1 0名受试者采取眼局部对气态甲醛的暴露 (约 0、 1 .0、 2 .0和 3.0 mg/ m3,5 min) ,测量了受试者的眨眼频率和眼刺激感觉强度。结果 :甲醛暴露水平与眨眼频率之间 (r=0 .980 ,P<0 .0 5 ) ;甲醛暴露水平与眼刺激感觉强度之间 (r=0 .985 ,P<0 .0 5 )均呈暴露 -剂量关系 ,两种生物标志之间有高度相关性 (r=0 .985 ,P<0 .0 5 )。结论　眨眼频率作为反映刺激作用的生物标志比眼部刺激感觉强度更为客观 ,因而更具有科学性。     

学龄前儿童异常瞬目的相关因素分析

目的探索学龄前儿童异常瞬目的相关因素。方法收集西安市儿童医院2011年871至2012年9月门诊诊断为异常瞬目的83例学龄前儿童的临床资料,进行比较分析。结果83例畀常瞬目的学龄前儿童中,男65例（占78．31％）,女18例（占21．69％）;有眼表疾患者57例;伴有行为异常者64例;偏食或食欲差者30例;屈光不正者23例。眼表疾患、行为异常、屈光不正为异常瞬目的危险因素（OR值分别为300．385、239．194和19．699,均P〈0．05）。结论儿童异常瞬目是一种多因素疾病,与眼表疾惠、行为异常及屈光不正有相关性,应采用综合措施进行防治。     

Micro-determination of fluoride in biological samples by pyrohydrolysis and flow-injection analysis using a fluoride ion-selective electrode

An apparatus has been developed for the isolation of fluoride in biological samples through pyrohydrolysis. With this apparatus, it is possible to determine both organic and inorganic fluorocompounds with a recovery close to 100% and precision within 5%. The high recovery rate can be expected even for highly heat-resistant compounds such as CaF2, without using WO3 as a catalyst. For determination of the isolated fluoride, a separate apparatus was developed in which flow-injection analysis was used in conjunction with a fluoride ion-selective electrode as a detector. With this apparatus, fluoride in a sample solution with a volume as small as 0.2 ml, and at a concentration as low as 0.5 microgram/l, can be determined within 3 minutes with a precision of several percent. Combined use of the two apparatuses makes it possible to determine fluoride in different biological samples within 10-15 minutes with a precision of several percent, free from external contamination. By selecting suitable conditions for analysis and using a 1 g sample, it is possible to determine fluoride at a concentration as low as 5 ng/g. By employing these apparatuses, the fluoride content in different biological samples has been determine and the effectiveness of their use confirmed.     

针刺对运动性生理心理疲劳的调节作用

目的 运动性疲劳是运动训练学、运动心理学、运动医学研究的重要课题，本研究的目的在于揭示运动性疲劳的本质。方法 本研究对某全训部队官兵运动性生理、心理疲劳进行全面观察。结果 对照组情绪状况用情绪状态量表(POMS)调查测定，随着运动量的增加，抑郁越来越重，疲劳亦逐渐产生；精力下降的同时，紧张、愤怒等情绪较运动前明显。观察组通过针刺，简单反应时(RT)与内光融合频率(CFF)针剌前后对比均有差异，针刺后RT延长，CFF降低。血红蛋白(HGB)、血乳酸(Bla)、Glu、LDH、CPK各项指标均明显改善。结论 针刺可以反射性地引起中枢神经向应激态转变，从而起到调节和改善机体疲劳状态。     

有限元法在医疗器械设计中的应用

有限元法是机械工程中用来分析结构应力应变的一种数值方法,该方法已经被应用到医疗器械尤其是骨折固定器的设计中。本文以骨折外固定架为例,通过对某型外固定架的抗压、抗弯和抗旋性能的分析,说明在医疗器械的设计阶段,采用有限元法可以使设计者了解其力学特性,发现强度或刚度的薄弱点,从而改进和优化设计。     

Serial prealbumin levels as predictors of outcomes in a retrospective cohort of peritoneal and hemodialysis patients.

OBJECTIVE: Although earlier research has suggested that baseline prealbumin level is an independent predictor of outcome among dialysis patients, the prognostic importance of serial prealbumin levels is less clear. The present study had 3 objectives: first, to determine if prealbumin (a marker of visceral protein stores with a relatively short half-life) predicts subsequent albumin levels taken at least 1 month later; second, to examine the association between serial prealbumin levels and clinical outcome; and third, to examine the association between changes in prealbumin level and outcome. DESIGN: The prognostic value of serial prealbumin levels was examined by linear regression analysis and Cox hazard models in an observational cohort study using a repeated measures design and time-dependent covariates. SETTING: Patients were followed by a tertiary care center, receiving hemodialysis (HD; at either an in-center dialysis unit or one of several satellite units operated by the hospital) or home peritoneal dialysis (PD). PATIENTS: A retrospective cohort was identified consisting of 268 incident and prevalent chronic HD and PD patients receiving dialysis from June 1998 to September 1999. MAIN OUTCOME: The study examined the association between serial prealbumin measurements and future laboratory and clinical outcomes (albumin, hospitalization, and death). RESULTS: Serial prealbumin values were independent predictors of future albumin levels among HD patients (P =.04), but not PD patients. Independent predictors of hospitalization included diabetes for PD patients (P =.0012) and advanced age for HD patients (P =.0008). Advanced age and diabetes were independent predictors of death for both HD (P =.0001 and P =.0368) and PD patients (P =.0014 and P =.0164). Serial prealbumin values, measured as time-dependent covariates, did not predict hospitalization or death. Further analyses examined the prognostic value of changes in prealbumin and albumin values as time-dependent covariates. The final multivariate analysis identified low baseline albumin level as an independent predictor of hospitalization among HD patients (P =.0282), whereas low baseline prealbumin was an independent predictor of death for HD patients (P =.0001). Interestingly, negative changes in serial prealbumin measurements were also independent predictors of death among HD patients (P =.0025). CONCLUSION: Serial prealbumin measurements predict subsequent albumin values among HD patients. As well, low baseline prealbumin level is an independent predictor of adverse outcome among HD patients. Although repeated prealbumin measurements in and of themselves were of no added prognostic value, falling prealbumin values identified by repeated measurements were additional independent predictors of death. These results support the clinical utility of regular prealbumin monitoring among HD patients.