Search

Power line communications (PLC) technology utilizes the power grid infrastructure and its wiring as a communications channels for information transmission and reception. No need to install new structure and wiring together with the wide spread availability and easy accessibility of power grids are the main reasons for appearance and development of this technology over the years. Nowadays, one century after the discovery of this technology, existing PLC systems can be subdivided under three main classes of ultra-narrowband, narrowband and broadband systems, where, each one has been dedicated for a special application and is based on a specific standard. Within the framework of aforementioned grouping, this paper provides a comprehensive study on the historical evolution of this technology which includes from the historical review, advantages, telecommunication challenges and application areas of this technology to the presentation of worldwide standardization projects, equipment and their providers, and its key role on making the future gird smarter. [ABSTRACT FROM AUTHOR]

Introduction: The objective of this study was to survey needs assessment for the required and proposed educational courses in order to promote entrepreneurship and job finding among the students and graduates in universities of South Iran. Material and Methods: The present descriptive-analytic research was conducted using a questionnaire containing 19 subjective questions for needs assessment. The sample size included 300 students and 200 graduates (and employed GPs) of Shiraz, Bushehr, Yasooj and Bandarabbas universities of medical sciences selected randomly. Questionnaires were filled by the participants. Results: The results showed that there was a significant difference between theoretical education and job requirements. Also, there was a significant difference between students and the employed graduates regarding learning a foreign language. The students group was more familiar with the global systems of the medical courses than the graduates; this could be attributed to the change in educational structure as well as technological revolution. Regarding innovation and creativity, the difference was significant between the two groups. Group A does more teamwork than group B; as to the introduction of the job, the difference was significant between the two groups Conclusion: The findings indicated that negligence and lack of needs assessment have kept the students away from practical work and encounter with the related problems. The students generally believe that employment could be gained through nepotism in the first place and based on practical and scientific capabilities in the second place. This problem could be solved through educational courses for teaching computer and language skills, management, etc. Moreover, by establishing an organization for monitoring the employment process, disappointment among the students and academic staff especially physicians could be eliminated. [ABSTRACT FROM AUTHOR]

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movement. Considering the contradictory findings in this regard, this study was designed to assess the effect of low level laser therapy (LLLT) on the rate of orthodontic tooth movement. Materials and Methods: In this randomized clinical trial study, 12 patients (4 boys and 8 girls; average age:16.9 ± 3.4) with extracted upper first premolars and required canine retraction into extraction site were included. While in both sides canines were retracted by NiTi coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done (on the buccal and palatal mucosa by slow movement of probe) at the beginning of the first month. Impression and cast fabrication performed at the beginning of retraction, one and two months later. The amount of retraction on the cast was measured with the aid of a reference plaque fabricated on the rogae using a digital caliper. Data were analyzed using paired sample T-test and one-sample Kolmogorov-Simirnov test. Results: There was no significant difference in the amounts of canine movement between laser exposed and control sides (P>0.05). Conclusion: The energy dose of laser used in this study (72 J per each tooth) was not appropriate for increasing dental movement. [ABSTRACT FROM AUTHOR]

Background and Aim: Stroke is the third leading cause of death, second cause of long-term disability and one of the very important challenging in life. The aim of this research was to explain the barriers and facilitating factors affected on stroke patients' life, and to identify relationship among them with demographic factors and severity of disease. Materials and methods: The descriptive-analytic technique was used. All patients who suffered from stroke were recruited in Kerman city. Finally 83 patients were selected, and data were gathered by demographic qualification questionnaire, proven questionnaire by researcher for studying barriers and facilitating factors (after testing validity and reliability), and NIHSS tools . Then, data were analyzed by using descriptive and referential statistics ANOVA test, T-Test, and Pearson coefficient correlation by SPSS software (ver. 16). Results: The findings showed that patients had more problems in the domains of politics, environmental factors, physical, and economic status. Also, they introduced social support from friends, family and prayer as facilitating factors in their lives. There was a significant positive relationship between age and physical and economical problems. Women have used social support and religious coping more than men. Married patients received more social support and their physical and economic problems raised less. Conclusion: Patients with higher severity of disease had more psychological problems such as depression and worry about future and Patients with lower socio-economic status more faced with barriers. [ABSTRACT FROM AUTHOR]

Background and Aims: The main purpose of orthodontic treatment is normal positioning of teeth in three dimensional plans, including the mesiodistal inclination. In this study, mesiodistal axial inclination of posterior teeth in skeletal class II was evaluated and compared with that of posterior teeth in skeletal class I. Materials and Methods: Seventy-eight panoramic radiographs for subjects between 12 to 24 years old with skeletal class I and 78 panoramic radiographs for subjects between 12 to 19 years old with skeletal class II were selected. All of the subjects were in permanent dentition with no tooth missing, no tooth extraction, no impacted tooth, and no crowding in posterior teeth. Two reference lines were established over each radiograph: the upper one passing through the most inferior point of right and left orbits lower one passing through the right and left mental foramina. After that, the long axis of teeth was traced (the image of root canal in single-rooted teeth, mean image of buccal and palatal canals in upper premolars, mean image of mesial and distal canals in lower molars, and the image of palatal canal in upper molars.). The mean values for two skelotodental classes were analyzed using T-test. Results: The results showed that there was significant difference between (P<0.05) mesiodistal axial inclination of teeth 15, 16, 17, 25, 26, and 27 in upper jaw in skeletal class II compared with that of the same teeth in skeletal class I, which was more mesially in skeletal class II. Mesiodistal axial inclination of teeth 36, 46, and 47 in lower jaw was more mesially in class II compared with that of the same teeth in class I. For other teeth there were no significant differences between two skeletodental classes (P>0.05). Conclusion: The mesiodistal axial inclination of upper molars and second premolars and lower molars in class II was more mesially compared with that of the same teeth in class I. [ABSTRACT FROM AUTHOR]

Background and Aims: One of the common human evolutionary anomalies is dental Missing. Evolution of dental system is toward deduction of teeth number. The Missing of third molar is interesting subject for dentists and genetic researches because of its variety in different races. Consideration of bilateral effect of third molar Missing with jaw relation is an important subject. The aim of this study was to evaluate the third molar missing in Cl I and Cl II skeletal (without rotation) and comparison of them together. Materials and Methods: The patients of the orthodontic department of school of Dentistry (Tehran University of Medical Sciences) were analyzed. About 121 patients had Cl I and 60 patients had ClI jaw relation. This relation identified based on cephalometric lateral radiographic ANB corner angle. Patient who had rotation in maxilla or mandible based on SN-Go Gn angle were excluded. The incidence of third molars agenesis in individual dentition quadrants, upper and lower jaw and right and left side of dentition was examined from panoramic radiography. AChi-square test was used for statistical analysis of data. Results: Missing of one or more third molar in skeletal Cl I and Cl II was 43% and 33.3%, respectively. Missing of one or more third molar in Cl II was fewer than Cl I, but no statistically significant differences were seen between them (P>0.05). Conclusion: There was not a direct relationship between jaw relation and third molar missing. [ABSTRACT FROM AUTHOR]

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movements and to inhibit the pain during tooth movements. Considering the contradictory finding in this respect, the effect of low level laser therapy (LLLT) was evaluated on the pain during orthodontic tooth movement. Materials and Methods: In this randomized clinical trial study, 12 patients were included with extracted upper first premolars and required canine retraction into extraction site. While in both sides canines were retracted by Niti coil spring, one side was exposed to GaAlAs laser (890nm). LLLT was done on the buccal and palatal mucosa by slow movement of probe. The patients were asked about their pain on both sides 2 days after beginning of retraction. Pain measurement was evaluated with VAS. Results: Pain perception in LLLT side was significantly decreased (P=0.007). Conclusion: Based on the results, single irradiation of GaAlAs laser (12 J energy per tooth) can decrease pain perception. [ABSTRACT FROM AUTHOR]

Background and Aim: Unwanted pregnancy is a widespread problem globally and in Iran, which can lead to low birth weight (LBW)-one of the most important causes of mortality in newborns. This study was conducted to assess the risk factors among women with unwanted pregnancies leading to delivery of LBW infants. Other LBW risk factors were also studied. Methods and Materials: This was a prospective cohort study performed during March 2004 to April 2005 in the health centers of Shemiran, north of Tehran, Iran. A sample of 180 mothers, 15-49 years old, with an unwanted pregnancy (case group) and 430 mothers, in the same age group, with a wanted pregnancy (control group) were compared. To determine the effect of unwanted pregnancy three major type of variables (background, maternal, and neonatal variables) were selected, and the mothers were followed up for 11-12 months (from the first referral for prenatal care to about 2 months after delivery). Statistical univariate analyses were performed using the tand χ2 tests. Also, multiple logistic regression was employed to identify the risk factors associated with LBW. SPSS 11.5 for windows was used for data analysis. Results: The unwanted pregnancy prevalence was 11.7%. The mean of Apgar score was 8.6 in the case group and 8.9 in the control group, the difference being statistically significant (p<0.001).Mean birth `1234t5weight of neonate in the case group was about 2.984kg vs. 3.14kg in the control group, and the difference was statistically significant (p<0.001). Univariate analysis showed that LBW was related to unwanted pregnancy (p<0.001), gestational age (p<0.001), mother's age (p<0.001), mother's marriage age (p<0.001), birth order (p<0.001), number of past pregnancies (p<0.001), family size (p<0.001), number of abortions (p<0.001), attempt to abort (p<0.001), high blood pressure (p<0.001), and diabetes (p<0.001). Finally, multivariable analysis revealed that LBW was only associated with unwanted pregnancy, high blood pressure, and diabetes in mothers, with adjusted odd ratios of 2.22, 2.81 and 3.55, respectively (p<0.05). Conclusion: Prevention of unwanted pregnancies, increased gestational age, and appropriate management of mothers' chronic diseases can reduce the risk of LBW. [ABSTRACT FROM AUTHOR]

Background and Aim: Job enrichment is a method that has been used to increase employee satisfaction and work motivation. The Hackman and Oldham job characteristics model (1976) has served as the foundation for many job enrichment efforts. In particular, a considerable amount of research has been devoted to the study of the job characteristics-job satisfaction relations. Te purpose of this study was to statistically determine the relation between job characteristics and job satisfaction among employees of hospitals affiliated to Tehran University of Medical Sciences (TUMS) in 2007. Materials and Methods: This study was a cross-sectional one, including 6 TUMS-affiliated hospitals-Emam, Shariati, Baharlo, Ziaeian, Madaen and Azadi. The sample size was 400, consisting of 200 administrative employees (50%), 151 nurses (38%) and 49 physicians (12%). The random sampling and stratified proportional sampling methods were used to select the hospitals and interviewees, respectively. Two questionnaires were developed and used to identify job characteristics and job satisfaction: 1) job diagnostics surveys (JDS) and 2) Hertzberg's job satisfaction questionnaire. The reliability of the questionnaires was ascertained by test-retest using the Pearson correlation coefficient (r = 0.88). Linear-by-linear association and ordinal logistics regression analysis were used for analyzing the data gathered. Results:The relations between the Motivational Potential Score (MPS) and job characteristics (except for feedback) with job satisfaction were statistically significant (p<0.05). Task identity was the most effective determinant of job satisfaction. Conclusion: It appears that all the job characteristics (except feedback) are important determinants of job satisfaction of the hospital employees. Although the work environment is in need of restructuring, it is important to note, from a positive perspective, that the job characteristics discussed in this study are readily amenable to change job satisfaction at the organizational level. [ABSTRACT FROM AUTHOR]

Background and Aim: Work-related Musculoskeletal Disorders (WMSDs) are the most prevalent occupational diseases and injuries. The aim of this investigation was WMSDs risk factors study in building construction industry by PATH (Posture, Activity, Tools and Handling) method. Materials and Methods: This analytical-descriptive and cross-sectional study was conducted in four construction sites. A total of 3100 observations of 89 workers in 14 jobs were obtained. The percent of time determined for trunk, legs and hands postures, and manual material handling activities, used tools and handling in job tasks. Results: Trunk, legs and hands postures, tools and objects weight differed significantly between stages (P<0.0001). Neutral trunk posture was observed frequently. Neutral legs and hands postures were observed greater than %50 and %80 of the time respectively in studied workers. Tools are used with different frequency in studied jobs. Loads with less than 5 Kg were handled repeatedly. Conclusion: The result of this study can be used to reduce musculoskeletal disorders in construction workers. This study revealed construction workers spent more time with neutral postures. But ergonomic interventions should be accomplished in specified jobs. [ABSTRACT FROM AUTHOR]