پیام حیدری

Sound is one of the most influential exogenous factors affecting the processing mechanisms of the human brain that play a major role in the occurrence of human errors and occupational accidents. Low-frequency noise is one of the most important sources of noise in the environment, and even at low levels it is annoying and affects people's cognitive performance. Some of the individual differences, such as personality type, hand superiority, neuroticism, and individual sensitivity are factors that influence the effect of sound on cognitive functions. The purpose of this study was to investigate the effect of personality type on cognitive functioning in three situations before, during and after exposure to low frequency noise.

The present study is an empirical basic science. The study population was students of Hamadan University of Medical Sciences through purposive sampling (60 extroverted and 60 introverted). All experiments were performed in the Faculty of Health of Hamadan University of Medical Sciences in a room with controlled acoustic and physical conditions in March, 2016. Eiseng personality questionnaire was used to determine personality type. Simulating the real-world environment of each of the subjects in the industry were exposed to the most intense noise in the industry (50 and 70 dB) for 40 minutes. Each of the subjects underwent cognitive performance in three positions before and during and after the exposure using continuous audiovisual performance test. Environmental conditions were maintained under conditions of thermal comfort and equivalent to a humidified temperature of 18 ° C and relative humidity of 50% without disturbing airflow. Also using fluorescent lamps and halogen lamps of 500 lux with optimum luminance levels were provided and kept constant during all tests. In this study, the recording of industrial ventilation in the workplace was performed using the Cool edit Program software in the frequency band. It is a powerful software for generating sound at different frequencies, especially low frequency sound. When playing the sound, the sound pressure equivalent to the ear of the test subjects was measured and in the sitting position. The sound meter used in this study is SVANTEK Model 971 manufactured by Polish-American Company, which operates according to IEC 61672, which has the capability of analyzing 1/1 and 1/8 octaves. The speakers used in this study are spherical-shaped speakers with a SWA-100 amplifier to amplify the sound at low frequencies that produce a sound similar to the workplace. After each step, the groups were replaced to eliminate the noise exposure effect and to avoid cumulative fatigue in the second level, a 24-hour interval was considered. Data were analyzed by SPSS 20 software and repeated measure ANOVA.

The mean age of the subjects was 23.94 with a standard deviation of 3.25. The distribution of the test subjects was gender uniform and 85% of them were single and the rest were married. Most of the participants in this study were undergraduates of health sciences and 80% of them. The results showed that the cognitive functions of extroverted and introverted individuals were different in the three situations before, during and after exposure to noise. The results indicated that introverts in the pre-exposure condition and extroverts performed better in the exposure conditions. Also, with increasing sound level from 45 to 65 dB, there was a significant difference (p <0.05) between extroverted and introverted individuals 'cognitive functions, which improves extroverted individuals' cognitive functions. The findings also showed a significant relationship between sound and sex.

The findings of the present study provide good evidence for the difference between introversion and extroversion in the tendency to environmental stimuli. The results of this study show that exposure to low frequency noise was influential in the components of participants' cognitive functions There is a significant relationship between the increase in sound level and the components of cognitive functioning with personality type. When exposed to noise, extroverts had higher cognitive performance components. The better performance of introverts in later exposure situations indicates their avoidance of stimulation and their tendency to silence a natural and genetic issue. Accordingly, the effects of personality type should be taken into account in job posts and sensitive occupational tasks that require the use of cognitive functions.

Assembly lines are associated with health risk and musculoskeletal disorders, particularly in the upper limbs. The aim of this study was to analyze three risk factors of posture, duration and force by using the postural ergonomic risk assessment (PERA) method in the workers of the assembly unit of automobile parts.

This descriptive cross-sectional study was conducted in the assembly unit of one of the auto parts manufacturing industries. Using the occupational task analysis method, task identified in one hierarchical task analysis (HTA) was divided into a set of sub-tasks. Risk factors of posture, duration and force were assessed by PERA method for each task.

Based on hierarchical task analysis, the vehicle assembly task included four sub-tasks of deburring, washing, vacuum testing and packaging which consisted of a total of 15 operations. Based on the risk factor analysis, we found the greatest risk of force in loading operations and the most awkward posture in sub-task of deburring and packaging. The risk level was estimated high and unacceptable in all three sub-tasks of washing, vacuum testing, and packaging.

Factors of force, posture and duration of work contributed to unacceptable risk in the loading operations of the cylinder head on the pallet and placing it inside the carton. Using tables with adjustable height (reducing the vertical distance between origin and destination) and rotating plates at all angles, together with reducing the exposure time to risk factors by rotation programs for workforces can prevent forward and lateral trunk and neck bending and reduce unacceptable risk levels.

Work-related musculoskeletal disorders are the cause of most of the disabilities and labor-induced absences in developing countries. Therefore, this study aimed to investigate the association between occupational and individual risk factors and the prevalence and outcomes of musculoskeletal disorders among the rescue department employee. This cross-sectional study was conducted among the rescue department employees of Qazvin. One hundred fourteen staffs were recruited in year 2016. Data gathering tool was Nordic questionnaire. Descriptive statistics and logistic regression test were conducted using SPSS (ver 18). Based on this study, 68.4% of the staff in the rescue department has suffered in one of the body regions during the last year. Musculoskeletal disorders in employee had 2.7 times negative association with lower level of education and higher work stress accordingly (staff with a high school diploma compared to bachelors) and (people with higher compared to higher stress). The Red Crescent workers were at higher risk of musculoskeletal disorders and work absence than fire workers (5.2 times in single-variable analysis and 13.09 in multivariate analysis). Factors including age, weight, work hours and history, education, type of job and work-related stress can affect the prevalence of musculoskeletal disorders and its consequences. Among these factors, educations, type of job and stress during work have the most impact on prevalence of musculoskeletal disorders and whole body and shoulder pain.

Global Harmonized System (GHS), is a system for labeling chemicals. The aim of present study was to investigate the effect of rapid training intervention on student’s awareness toward Global Harmonized System.
Material and This research was a descriptive-analytical and cross-sectional study conducted among 317 students of Public Health and Allied Medical Sciences faculties of Qazvin University of Medical Sciences in 2016 year. Sampling was done in a random base among the study population. A general demographic and a global system labeling questionnaires were used for data collection. Training intervention for familiarization with the chemical safety labels, types of chemicals hazardous was implemented using a rapid training method and PowerPoint tool. Data analysis was performed by T-Tests, ANOVA and T-Paired using the SPSS version 18. Allied medical sciences students with an average of 48.31% before training and occupational health students with an average of 94.44% correct answers after the training have the highest awareness on global harmonized system (GHS). The findings also showed that training has a significant effect on the awareness on the international labeling system. The present study showed that initial awareness of the students is low concerning the global harmonized system. So, the prevention of serious accidents in the laboratory environment, the implementation of a short training course would play a significant role in raising students’ awareness about chemical hazards and will control unsafe behaviors during laboratory works.

This paper presents a novel method for the fabrication of polymeric deformable micromirror based on electrostatic actuator. Deformable micromirros are commonly used to correct optical wavefront aberrations in the adaptive optic systems, and thus, they need a deformable diaphragm. In this study, the diaphragm of micromirror is made from SU-8 polymer which is mounted on the fixed electrode arrays. This polymeric diaphragm with a Young’s modulus of 50 times less than conventional silicon samples provides more deformability and, as a result, aberrations modifications with lower voltage values are reached, so that the diaphragm with a radius of 2.5 mm and a thickness of 10 μm moves about 4μm by applying the voltage of 120 volts. Furthermore, polymer-based fabrication processes are more simple and cost-effective rather than silicon-based devices. However, they suffer from lower surface roughness compared to silicon-based counterparts. In order to overcome this issue, we used a new technique for the manufacture of micromirror, which, in addition to all the advantages of a polymeric mirror, provides similar surface smoothness of the silicon samples. The result of roughness measurements showed a rough surface variance of 20 nm. The Finite Element Modeling is also used to optimize the device structure design.

The study of human error is very important because many decisions in medical emergencies are taken in a shift. In work with patient, medical error is a serious and inevitable threat for patient safety. Therefore, the aim of this study is identification and evaluation of human errors among Qazvin emergency medical personnel by using Cognitive Reliability & Error Analysis Method (CREAM) technique. This descriptive and cross-sectional study was conducted using CREAM technique in 2017. In this study, after hierarchical task analysis of medical emergency duties, the work sheet of CREAM technique was completed through observation and interviews with the medical emergencies. Data were analyzed using SPSS-20. In this study, 4 main tasks and 24 sub-tasks were analyzed. However, the highest probability of general error was predicted in technician task (0.01771). Also from the errors detected, execution cognitive function with 39.69% and interpretation error with 33.33% had the highest values relative to other cognitive functions. False recognition in physical examination and taking and presenting history to doctor via wireless with 0.03169 had the highest cognitive error probability. According to the results, time to do work, empowerment, work condition and perform two or more task simultaneously factors affecting performance reduction. Therefore, solutions for improving conditions and more productivity of emergency medical staff and reducing human error in this group is suggested: improvement of work conditions, increase empowerment, perform two or more work simultaneously by high-ability people, set up regular shifts and work schedule for personnel, educational programs based on personnel needs and joint meeting to increase efficiency.

Body anthropometric dimensions are among the factors affecting the maximum oxygen consumption. This study aimed to predict maximum oxygen consumption based on anthropometric dimensions in medical emergency students.
This cross-sectional analytical study was conducted among 56 medical emergency students from Qazvin University of medical sciences. Initially, physical activity readiness Questionnaire (PAR-Q) was applied to ensure the full health of participants to inter the study. Maximum oxygen consumption measured using Gerkin treadmill test. Anthropometric dimensions were measured by tape measure, anthropometer and kolis. Obtain data was analyzed by Pearson product moment correlation and multiple linear regressions in SPSS 19 software.
The mean age of participants was 21.69 years. The mean of maximum oxygen consumption and mean of foot length estimated 4.17 L/min and 96.35 cm, respectively. There was significant correlation between the maximum oxygen with the anthropometric dimensions. Variables of dimensions of abdomen circumstance, foot length and leg circumstance predicted 63.7 percent of the maximum oxygen consumption.
The results indicated that the anthropometric dimensions are the factors affecting the maximum oxygen consumption among medical emergency student. So, it is necessary to be paid attention to anthropometric dimension in selection of students and matching between person capabilities with energy.

Work-related musculoskeletal disorders, is the cause of most disability and absences created to work.
This study was done in order to survey of effective occupation risk factors on absence from work and going to the doctor caused by musculoskeletal disorders.
This cross-sectional study was done among 114 subjects from rescue groups employees in the city of Qazvin in 2016. Data were collected by Nordic questionnaire and demographic characteristic. Data analyzed by using descript statistic and logistic regression test.
Findings: As the results, eighteen (15.7%), and forty-two (37%) rescue work employees were absent from work and gone to the doctor respectively due to pain in the one of body regions during the past year. Occupation group of Red Crescent was absent from work and going to doctor than firefighter due to musculoskeletal disorders in univariate, and multivariate analysis (5.2, 13.09 times) respectively.
Risk factors including work history and kind of job can influence on the consequence of musculoskeletal disorders.

Given the increase of road transportation of dangerous materials, if an accident occurs, the first groups that present at the scene are rescue groups (emergency¡ red crescent and firefighters). The aim of this study was to investigate the validity and reliability of the questionnaire assessing level of knowledge in the rescue personnel regarding warning signs mounted on the road heavy machinery.
Material and Firstly, a multiple-choice questionnaire was designed using the literature and material safety data sheets (MSDS). Validity of the questionnaire was examined using the viewpoints of 10 experts. The reliability of the questionnaire was assessed using test-retest in 20 subjects of the rescue groups in two-week intervals. The cut point of the questionnaire was determined by the Receiver Operating Characteristic (ROC).
The mean of age and work experience of the participants was 32.42 ± 2.57 and 7.75 ± 2.70. The results of correlation between the questions of the test showed that Cronbach’s alpha is 0.708. Also, the stability and reliability of test scores over time showed that the correlation between the questions in the first and second series was significance at acceptable level (r=0.698 with P-value=0.012(. The best value of cut point in the questionnaire of knowledge in the rescue personnel as obtained 18.5, with the sensitivity of 60% and specificity of 50%.
The validity and reliability of the knowledge assessment questionnaire in the rescue personnel were confirmed regarding the warning signs mounted on the road heavy machines; therefore, it can be used in the future studies.

Manual handling of disabled patients is one of the important and effective factors in acute low back pain among exposed nurses. The present study was conducted with the objective of quantitative risk assessment of patient manual handling among nurses in wards of one of the hospitals in Tehran using MAPO method.
The present study was conducted as an analytical-cross-sectional study in 26 wards of one of the hospitals in Tehran city. Samples were selected by census method from nurses and paramedics of different wards of hospital. Data collection was performed using demographic information and MAPO checklist.
The highest score of MAPO were, respectively, related to wards of DI clinic (score, 14.7), men orthopedic (score, 6.3), and general operating room (score, 57). 53.8% of hospital wards were at the level 2 corrective action, which indicated that the risk of musculoskeletal disorder is 2.4 times higher than level 1 corrective action.
Given that the proportion of disabled patient in cooperation and/or partial cooperation, lifting tools, auxiliary, wheelchair, and training have the most role among risk factors for above-mentioned wards, increasing the number of human resources and wheelchair, use of lifting and auxiliary tools and training reduce MAPO score and consequently the risk of musculoskeletal disorders.

Muscle-skeletal disorders are one of the most common job related disorders in industrial workplaces and they’re caused because of different reasons. The study purpose was ergonomic assessment by using key indicator index (KIM) and it was done in order to reduce injuries in bottle-making salon in one of the detergent producing industries in Qazvin province.
This study is an intervention study and it consists 25 workers and was done in a bottle-making salon in one of the detergent producing industries in 2016. To data collection, we used Cornell questionnaire and key indicator index assessment method before and after the ergonomic interventions. We analyzed the data by descriptive analytical tests using SPSS 16 software.
According to the results in the bottle production task (risk score: 4), the risk score decreased significantly by redesign (risk score: 2). Also based on the results in bottle's material supply task that workers used to do it by manual material handling (risk score: 3), by redesign, risk score decreased significantly (risk score: 1).
In this study, muscle-skeletal disorders decreased meaningfully by workstation ergonomic redesign after 5 months that we started the interventions.

Heavy load lifting or occupational and individual factors are effective hazard agents in the occurrence of musculoskeletal disorders. Therefore, the aim of the present study was investigating the correlation of musculoskeletal disorders with work ability index and allowable load lifting limit.
This analytical and cross-sectional study was conducted using census (n = 60) among the kitchen workers in Qazvin teaching hospitals in 2016. Data were collected through questionnaires including pain prevalence, work ability index and allowable load lifting limit. Data was analyzed by single and multiple regression logistic using SPSS 16 software.
The highest prevalence was observed in the lower back (78.3%). Of the workers, 61.7% reported a good level of work ability index and 58.3% of the workplaces were in unsafe conditions of load handling. Unsafe condition alone increased the prevalence of shoulder and neck pain about 7 times and the lower back pain 4 times, and in interaction with other risk factors, the prevalence of neck and shoulder pains had 25 and 28 times increase, respectively. Also, subjects with good levels of ability compared to subjects with excellent levels of ability were 9 times more in exposure of musculoskeletal disorders.
Risk factors such as body mass index, work ability and allowable load lifting limit can affect the prevalence of musculoskeletal disorders. So, selection of subjects with good and excellent work ability levels and compliance with the load limit are the effective solutions in increasing the productivity and reducing musculoskeletal disorders among kitchen workers.

Upper limb musculoskeletal disorders are related with repetitive work activities including force, posture and duration of work.
The aims of this study were identification of prone occupations to upper limb musculoskeletal disorders, assessment of jobs in two companies of producing detergents and assembly by two methods of strain index (SI) and hand activity level (HAL).
In this study descriptive-analytical and cross sectional that was done in 2015 in Qazvin, 50 subjects from practitioners of all of occupations were randomly selected (25 jobs) from two companies of producing detergents and assembly. Data were collected by body map and assessment methods of the strain index and HAL. Statistical analysis done by Spearman correlation coefficient and chi-square tests in SPSS 16 software.
Findings: The most of the prevalence musculoskeletal disorders were reported in the elbow 16.66% and in the wrist and shoulder 23.08% in producing detergents and in assembly factories respectively. According to the investigation by two methods SI and HAL, seven jobs (58.3%) in producing detergents and three jobs (23.1%) in assembly factories were in situation of caution or hazard. The results of the assessment upper limb by two methods showed significant correlation together (r=0.615 in producing detergents and r=0.603 in assembly factories with P The results of this study shows that the methods of strain index and hand activity level have significant correlation in the assessment of repetitive jobs and risk of upper limb musculoskeletal disorders.

Due to the fact that relief teams play an important role in all management phases of accidents, increasing awareness of these groups contributes to the increased participation in the reduction of casualties. Therefore, the aim of this study was to investigate the awareness of relief groups about the warning signs installed on heavy road vehicles.
In this descriptive-applied research, all personnel of relief groups (Firefighting, Emergency and Red Crescent) who have been located in Qazvin roads were selected in 2016. According to the official reports, 115 people were studied by using census method. For data gathering, a questionnaire is used to measure the level of awareness of relief personnel in relation to warning signs. Validity and reliability were calculated based on Lawshe’s formula (0.82) and alpha cronbach’s (0.71) respectively. Data was analyzed using descriptive statistics and logistic regression tests and SPSS-18.
Findings: The results are as follows: the average percentage of responses was exactly 55.1% and firefighters’ awareness was more than other groups. In addition, people with an associate degree, less than 12 years of work experience and ages 33 to 35 years had higher awareness of warning signs installed on heavy road vehicles.
According to the significant relationship between education and awareness level of relief staff about warning signs, there are several factors that increase the level of personnel knowledge such as encouraging employees to participate in higher academic levels, holding training courses more about warning signs and dealing with emergencies in road accidents in order to improve personnel’s level of knowledge

The maximum aerobic capacity or VO2max is a measure of the maximum volume of oxygen that can be absorbed by respiratory system and delivered to the acting muscles through blood flow. The aims of this study were to determine the correlation between the two methods of treadmill and step tests in estimating the maximum aerobic capacity and it's affecting factors among students of Qazvin University of Medical Sciences.
This cross-sectional study conducted among the 68 students (47 males and 21 females) that participated voluntarily. First, the participants completed physical activity readiness Questionnaire (PAR-Q) and demographic characteristics, and if they were met inclusion criteria, step and treadmill tests were done according to ASCM by treadmill and step tests according to ACSM and Gerkin protocols respectability.
The results showed that the mean and standard deviation of maximum aerobic capacity estimated from ACSM and Gerkin protocols were 2.86 ±0.66 and 1.86 ±0.32 respectively. Significant and Positive correlation were estimated between two test for maximum aerobic capacity via two protocols of ASCM and Gerkin (r=0.74 and p According to the results of almost the same ACSM and Gerkin tests, can be used step test instead of the treadmill test to estimate the maximum aerobic capacity. In addition to Physiological characteristics of the human such as sex, age, height and weight have main roles in maximum aerobic capacity.

In this paper a novel optical pressure and acceleration sensor based on micro electro mechanical systems (MEOMS) has been designed. For this purpose an integrated Mach- Zander interferometer has been used in LiNbO3 diaphragm. In this sensor, the strain caused by applied pressure or acceleration leads to a change in refractive index of the wave guide in the diaphragm due to the photoelastic effect. The refractive index change leads to a phase change in the light wave that propagates in the waveguide. This phase change is converted to intensity change using the Mach- Zander interferometer. The software ANSYS 14.5 was used for calculation of the strain in the diaphragm. The pressure and acceleration sensitivity of the designed sensor have been obtained 2.33×10-4 (rad /Pa) and 2.16×10-5 (rad.s2/m), respectively.

Listening to music during physical activity reduces the perceived stress on body. Hence, this study aimed to evaluate the effects of music genre and sound pressure level on calorie consumption and physical performance of students during treadmill tests.
In this cross-sectional study, 27 students were randomly selected. A demographic questionnaire, Borg Rating of Perceived Exertion Scale (RPE 6-20), and the Physical Activity Readiness Questionnaire (PAR-Q) were used for data collection. During flat and sloped treadmill running (five minutes at 6 km/hour), two pieces of music with fast and slow tempo (200 and 70 beat per minute) were also played at two sound pressure levels (60 and 80 dB). During the exercise, the students’ heart rate and calorie consumption were measured by a calorimeter (Beurer PM100). At each stage, the physical performance of the participants was estimated using the relevant equation.
The students had the lowest physical performance (61.48) when no music was played and the highest physical performance (92.48) with slow, loud music. The mean heart rate, calorie consumption, and perceived exertion were maximized without music and minimized when slow, loud music was played.
Playing soft music at high sound pressure levels can promote physical performance during exercise by decreasing heart rate, calorie consumption, and perceived exertion.

The maximum aerobic capacity (VO2max) can be used to evaluate the cardio-pulmonary condition and to provide physiological balance between a person and his job. The aim of this study was to estimate the maximum aerobic capacity and its associated factors among students of medical emergencies in Qazvin. This cross-sectional study was conducted in 36 male students of medical emergencies in Qazvin University of Medical Sciences، 2015. The Physical Activity Readiness Questionnaire (PAR-Q) and demographic questionnaire were completed by the participants. The participants meeting the inclusion criteria were assessed using the Gerkin treadmill protocol. Data were analyzed using Mann-Whitney U test and Kruskal-Wallis. Mean maximum aerobic capacity was 1. 94 ± 0. 27 L/min. The maximum aerobic capacity was associated with weight and height groups. There was significant positive correlation between maximal aerobic capacity and height، weight and body mass index. The Gerkin treadmill test is useful for estimation of the maximum aerobic capacity and the maximum working ability in students of medical emergencies.