The effect of cushion of air on vibration transmitted to vehicle drivers based on standard

زمینه و هدف: ارتعاش تمام بدن (WBV) از دلایل اصلی اختلالات اسکلتی عضلانی رانندگان است. یک روش برای کاهش ارتعاش استفاده از وسیله عایق می باشد. در این تحقیق، جهت کاهش میزان ارتعاش از یک تشکچه هوا استفاده شده و با اندازه گیری ارتعاش منتقله به رانندگان قبل و بعد از استفاده از تشکچه، اثربخشی آن در کنترل ارتعاش مورد بررسی قرار گرفت. روش بررسی: این مطالعه، مداخله ای و بر روی 95 نفر از رانندگان شرکت واحد اتوبوسرانی انجام شد. پارامترهای ارتعاش در سه محور ورود ارتعاش به بدن، در دو مرحله قبل و بعد از قرار دادن تشکچه بر روی صندلی راننده توسط دستگاه ارتعاش سنج اندازه گیری و با استفاده از آزمون آماری t زوجی مقایسه شدند. یافته ها: مقایسه مقادیر ارتعاش قبل و بعد از استفاده تشکچه نشان داد که ماکزیمم فشار (Pmax) در محورهای X،Y به ترتیب(m/s2) 2921/0 و (m/s2) 3081/0 کاهش (05/0

Comparison of Travel-Time and Amplitude Measurements for Deep-Focusing Time--Distance Helioseismology

The purpose of deep-focusing time--distance helioseismology is to construct seismic measurements that have a high sensitivity to the physical conditions at a desired target point in the solar interior. With this technique, pairs of points on the solar surface are chosen such that acoustic ray paths intersect at this target (focus) point. Considering acoustic waves in a homogeneous medium, we compare travel-time and amplitude measurements extracted from the deep-focusing cross-covariance functions. Using a single-scattering approximation, we find that the spatial sensitivity of deep-focusing travel times to sound-speed perturbations is zero at the target location and maximum in a surrounding shell. This is unlike the deep-focusing amplitude measurements, which have maximum sensitivity at the target point. We compare the signal-to-noise ratio for travel-time and amplitude measurements for different types of sound-speed perturbations, under the assumption that noise is solely due to the random excitation of the waves. We find that, for highly localized perturbations in sound speed, the signal-to-noise ratio is higher for amplitude measurements than for travel-time measurements. We conclude that amplitude measurements are a useful complement to travel-time measurements in time--distance helioseismology.Comment: 18 pages, 10 figure

Prevalence hearing loss of truck and bus drivers in a cross-sectional study of 65533 subjects

Background: Noise pollution is one of the most important occupational pollutants in heavy-vehicle drivers. Therefore, this epidemiological research was conducted with the aim of determining the prevalence of hearing loss in heavy-vehicle drivers in Iran. Methods: This cross-sectional research was conducted on 65,533 heavy-vehicle drivers including truck and intercity bus drivers from February 2006 to March 2016. The air and bone threshold of pure tone was measured for each ear at 0.5, 1, 2, 3, 4, 6, and 8 kHz by a skillful radiology expert. The obtained data from this research was analyzed in SPSS software using statistical tests such as descriptive analysis and paired t test. Results: Mean (standard deviation) of hearing loss in left and right ears of all people was 23.02 (8.25) and 22.48 (7.86), respectively. Paired t test showed that hearing loss difference in left and right ears was significant (P < 0.001). Mean and standard deviation of paired t test showed that hearing loss difference in left and right ears was significant in all frequencies except 1000 Hz (P < 0.001). Conclusion: The findings of this research generally showed that 26.8% of the studied drivers have hearing loss. Hearing loss in the left ear was more than right ear keywords: Bus drivers, Hearing loss, Prevalence, Truck driver

Designing and validation a visual fatigue questionnaire for video display terminals operators

Background: Along with the rapid growth of technology its related tools such as computer, monitors and video display terminals (VDTs) grow as well. Based on the studies, the most common complaint reported is of the VDT users. Methods: This study attempts to design a proper tool to assess the visual fatigue of the VDT users. First draft of the questionnaire was prepared after a thorough study on the books, papers and similar questionnaires. The validity and reliability of the questionnaire was confirmed using the content validity index (CVI) beside that of the Cronbach's Coefficient Alpha. Then, a cross-sectional study was carried out on 248 of the VDT users in different professions. A theoretical model with four categories of symptoms of visual fatigue was derived from the previous studies and questionnaires. Having used the AMOS16 software, the construct validity of the questionnaire was evaluated using the confirmatory factor analysis. The correlation co-efficiency of the internal domains was calculated using the SPSS 11.5 software. To assess the quality check index and determining the visual fatigue levels, visual fatigue of the VDT users was measured by the questionnaire and visual fatigue meter (VFM) device. Cut-off points were identified by receiver operating characteristic curves. Results: CVI and reliability co-efficiency were both equal to 0.75. Model fit indices including root mean of squared error approximation, goodness of fit index and adjusted goodness of fit index were obtained 0.026, 0.96 and 0.92 respectfully. The correlation between the results measured with the questionnaire and VFM-90.1 device was-0.87. Cut-off points of the questionnaire were 0.65, 2.36 and 3.88. The confirmed questionnaire consists of four main areas: Eye strain (4 questions), visual impairment (5 questions) and the surface impairment of the eye (3 questions) and the out of eye problems (3 questions). Conclusions: The visual fatigue questionnaire contains 15 questions and has a very remarkable validity and reliability. Usingthis questionnaire and its findings, one will be able to identify, assess and finally prevent the effective factors of VDT users' visual fatigue

بررسی تغییرات فیزیولوژیکی فشار خون، ضربان قلب و استرس شغلی کارگران کارگاه چوب بری در مواجهه با صدا

Background and Aims: The aim of this study was to investigate the level of noise exposure and its relationship with job stress, changes in blood pressure and heart rate among woodworking workshop workers. Materials and Methods: In this cross-sectional-analytical-descriptive study, 140 employees of a lumber workshop in Mazandaran province were selected and divided into case and control groups. Demographic information of employees was collected by questionnaire. Systolic and diastolic blood pressure were measured using mercury sphygmomanometer. Heart rate of the case and control groups was measured by Beurer pulse meter. The results were analyzed using SPSS software. Results: The results of noise measurements showed that the mean noise exposure in workers from 8-hour shifts was 92.11 dB and among non-exposed group was 74.48 dB. The mean systolic and diastolic blood pressure in the control and exposure groups were 124, 126, 80 and 82, respectively. Also, the mean heart rate of the studied groups was 74.9 and 75.83 beats per minute, respectively. There was no significant difference in systolic and diastolic blood pressure and heart rate between the two groups, (p&gt; 0.05). Conclusion: Based on the findings, the rate of systolic and diastolic blood pressure, as well as the heart rate and stress levels were higher in the exposed group as compared with the control group; however, the difference between systolic, diastolic blood pressure and heart rate between the two groups was not statistically significant. There was a significant difference in stress. It was found to be consistent with the results of some previous studies.زمینه و اهداف: هدف از انجام مطالعه حاضر بررسی میزان مواجهه با صدا و ارتباط آن با استرس شغلی، تغییرات فشارخون و ضربان قلب در کارگران کارگاه چوب‌بری بود. مواد و روش‌ها: در این مطالعه مقطعی- تحلیلی- توصیفی تعداد140 نفر از شاغلین یک کارگاه چوب بری در استان مازندران انتخاب و در دو گروه مورد و کنترل تقسیم شدند. اطلاعات جمعیت‌شناختی شاغلین با پرسشنامه گردآوری شد. میزان فشارخون سیستولیک و دیاستولیک با استفاده از فشارسنج جیوه‌ای و ضربان قلب گروه مورد و شاهد به‌ وسیله دستگاه نبض سنج Beurer مورد سنجش قرار گرفت. نتایج بدست آمده با استفاده از نرم افزار &nbsp;SPSS تجزیه و تحلیل شد. در تمام مراحل، ملاحظات اخلاقی مد نظر قرار گرفت. یافته‌ها: نتایج اندازه‌گیری صدا نشان داد، میانگین مواجهه با صوت در شاغلین مواجهه یافته در شیفت 8 ساعته 92/11 دسی‌بل و گروه بدون مواجهه 74/48 دسی‌بل است. میانگین فشار خون سیستولیک، دیاستولیک به ترتیب در دو گروه کنترل و مواجهه 124،126، 80 و 82 بود.&nbsp; همچنین میانگین ضربان قلب دو گروه&nbsp; به ترتیب 74/9 و 75/83 ضربه در دقیقه بود. همچنین تفاوت معنی‌داری در فشار خون سیستولیک و دیاستولیک و ضربان قلب بین دو گروه وجود نداشت (P&gt;0/05). نتیجه‌گیری: نتایج مطالعه نشان داد، میزان فشار خون سیستولیک، دیاستولیک، ضربان قلب و استرس در گروه مواجهه بیشتر از گروه کنترل بود و اختلاف فشار خون سیستولیک، دیاستولیک و ضربان قلب بین دو گروه&nbsp; از نظر آماری معنی‌دار نبوده و فقط در میزان استرس اختلاف معنی‌داری مشاهده شد

The effects of instruction and environmental demand on state anxiety, driving performance and autonomic activity: Are ego-threatening manipulations effective?

A small yet emerging body of research on the relationship between anxiety and driving suggests that higher levels of state anxiety may lead to more dangerous driving behaviours. The aim of the current research was to investigate the effects of increased state anxiety on driving behaviours within a simulated environment using instructional sets to manipulate anxiety levels. In Study One, whilst a set of safety-related instructions were able to increase state anxiety, this did not result in changes to driving behaviours. In Study Two, ego-threatening instructions were not able to successfully increase state anxiety. This has implications regarding instructional sets in research, including their task relevance and the necessity for a motivational incentive. However, when changes in anxiety were considered regardless of instruction group, Study Two found changes in SDLP and skin conductance levels related to state anxiety increases. As these effects were context specific, it is argued that some of these changes may be due to poorer processing efficiency, leading to suggestions about the types of behaviours that may need to be trained in potential therapies for those who show high state anxiety levels whilst driving

Anemia risk in relation to lead exposure in lead-related manufacturing

Abstract Background Lead-exposed workers may suffer adverse health effects under the currently regulated blood lead (BPb) levels. However, a probabilistic assessment about lead exposure-associated anemia risk is lacking. The goal of this study was to examine the association between lead exposure and anemia risk among factory workers in Taiwan. Methods We first collated BPb and indicators of hematopoietic function data via health examination records that included 533 male and 218 female lead-exposed workers between 2012 and 2014. We used benchmark dose (BMD) modeling to estimate the critical effect doses for detection of abnormal indicators. A risk-based probabilistic model was used to characterize the potential hazard of lead poisoning for job-specific workers by hazard index (HI). We applied Bayesian decision analysis to determine whether BMD could be implicated as a suitable BPb standard. Results Our results indicated that HI for total lead-exposed workers was 0.78 (95% confidence interval: 0.50–1.26) with risk occurrence probability of 11.1%. The abnormal risk of anemia indicators for male and female workers could be reduced, respectively, by 67–77% and 86–95% by adopting the suggested BPb standards of 25 and 15 μg/dL. Conclusions We conclude that cumulative exposure to lead in the workplace was significantly associated with anemia risk. This study suggests that current BPb standard needs to be better understood for the application of lead-exposed population protection in different scenarios to provide a novel standard for health management. Low-level lead exposure risk is an occupational and public health problem that should be paid more attention