Enhanced Traffic Signal Operation using Connected Vehicle Data

As traffic on urban road network increases, congestion and delays are becoming more severe. At grade intersections form capacity bottlenecks in urban road networks because at these locations, capacity must be shared by competing traffic movements. Traffic signals are the most common method by which the right of way is dynamically allocated to conflicting movements. A range of traffic signal control strategies exist including fixed time control, actuated control, and adaptive traffic signal control (ATSC). ATSC relies on traffic sensors to estimate inputs such as traffic demands, queue lengths, etc. and then dynamically adjusts signal timings with the objective to minimize delays and stops at the intersection. Despite, the advantages of these ATSC systems, one of the barriers limiting greater use of these systems is the large number of traffic sensors required to provide the essential information for their signal timing optimization methodologies. A recently introduced technology called connected vehicles will make vehicles capable of providing detailed information such as their position, speed, acceleration rate, etc. in real-time using a wireless technology. The deployment of connected vehicle technology would provide the opportunity to introduce new traffic control strategies or to enhance the existing one. Some work has been done to-date to develop new ATSC systems on the basis of the data provided by connected vehicles which are mainly designed on the assumption that all vehicles on the network are equipped with the connected vehicle technology. The goals of such systems are to: 1) provide better performance at signalized intersections using enhanced algorithms based on richer data provided by the connected vehicles; and 2) reduce (or eliminate) the need for fixed point detectors/sensors in order to reduce deployment and maintenance costs. However, no work has been done to investigate how connected vehicle data can improve the performance of ATSC systems that are currently deployed and that operate using data from traditional detectors. Moreover, achieving a 100% market penetration of connected vehicles may take more than 30 years (even if the technology is mandated on new vehicles). Therefore, it is necessary to provide a solution that is capable of improving the performance of signalized intersections during this transition period using connected vehicle data even at low market penetration rates. This research examines the use of connected vehicle data as the only data source at different market penetration rates aiming to provide the required inputs for conventional adaptive signal control systems. The thesis proposes various methodologies to: 1) estimate queues at signalized intersections; 2) dynamically estimate the saturation flow rate required for optimizing the timings of traffic signals at intersections; and 3) estimate the free flow speed on arterials for the purpose of optimizing offsets between traffic signals. This thesis has resulted in the following findings: 1. Connected vehicle data can be used to estimate the queue length at signalized intersections especially for the purpose of estimating the saturation flow rate. The vehicles’ length information provided by connected vehicles can be used to enhance the queue estimation when the traffic composition changes on a network. 2. The proposed methodology for estimating the saturation flow rate is able to estimate temporally varying saturation flow rates in response to changing network conditions, including lane blockages and queue spillback that limit discharge rates, and do so with an acceptable range of errors even at low level of market penetration of connected vehicles. The evaluation of the method for a range of traffic Level of Service (LOS) shows that the maximum observed mean absolute relative error (6.2%) occurs at LOS F and when only 10% of vehicles in the traffic stream are connected vehicles. 3. The proposed method for estimating the Free Flow Speed (FFS) on arterial roads can provide estimations close to the known ground truth and can respond to changes in the FFS. The results also show that the maximum absolute error of approximately 4.7 km/h in the estimated FFS was observed at 10% market penetration rate of connected vehicles. 4. The results of an evaluation of an adaptive signal control system based on connected vehicle data in a microsimulation environment show that the adaptive signal control system is able to adjust timings of signals at intersections in response to changes in the saturation flow rate and free flow speed estimated from connected vehicle data using the proposed methodologies. The comparison of the adaptive signal control system against a fixed time control at 20% and 100% CV market penetration rates shows improvements in average vehicular delay and average number of stops at both market penetration rates and though improvements are larger for 100% CV LMP, approximately 70% of these improvements are achieved at 20% CV LMP

Qualities of a Good English Language Teacher from the Perspectives of Textbook Authors in the Field of Language Teaching, Teachers, and Learners

Researchers in the field of language teaching have long been fascinated by the qualities of good teachers. Such qualities have rarely been approached qualitatively from different angles in a single study. Thus, this research aimed to unearth the qualities in question by employing a qualitative multimethod approach. To this end, 23 randomly selected standard language teaching textbooks were analyzed by two coders using qualitative content analysis. The judiciously adopted codes from the analysis were employed to design and carry out semi-structured interviews with nine effective language teachers as well as ten good learners nominated via purposeful sampling. The data gleaned from the semi-interviews were once again analyzed through qualitative content analysis. The collective initial coding of the three datasets resulted in thirteen themes: knowledge of pedagogy, rapport, critical thinking, empathy, rhetoric, knowledge of subject matter, enthusiasm, respect, humor, consciousness, fairness, authenticity, and physical attributes. Conducting a second-level coding, we uncovered two broad themes, namely personality and professionalism with the former being significantly weightier collectively. The application of Chi-Square at this point showed that the associations between the three datasets were meaningful. The findings of the semi-structured interviews of participant teachers and students corroborated those of authors in the field of language teaching. Also, rapport and pedagogy were respectively viewed as the most salient attributes associated with good language teachers by the interviewed informants. The study holds clear implications for interested researchers, language teachers, and teacher educators

Outcome of surgical treatment for proximal long segment post intubation tracheal stenosis

BACKGROUND: Post intubation long segment tracheal stenosis is a serious problem which usually requires multiple methods of treatment. The aim of this study was to evaluate the results of surgical treatment in long segment post intubation tracheal stenosis. METHODS: Between 2004 to 2008, 20 patients with proximal long segment tracheal stenosis and resection of over 40% of tracheal length, were analyzed in terms of age, sex, clinical symptoms, etiology of stenosis, length of stenosis and resection, role of suprahyoeid release with bilateral hyoeid bone cutting maneuver, post operative complications and life quality 3 year after surgery. RESULTS: M/F was 2/5, with the average age of 23.5 ± 0.5 years. Average length of stenosis was 4.2 ± 0.4 cm and the average length of resected segment was 5.2 ± 0.4 cm. Early postoperative complications occurred in 4 patients (20%), 5 patients (25%) had late stenosis and 4 of them were treated with multiple dilation and one patient needed tracheostomy and prolonged T. tube. We didn’t have any mortality. 80% of patients had excellent surgical results in follow up period. CONCLUSION: Surgery is the best method of treatment in long and multi segment tracheal stenosis

Transportation and Centering Ability of Neoniti and ProTaper Instruments; A CBCT Assessment

Introduction: Transportation is an important iatrogenic endodontic error which might cause failure. This study evaluated the canal transportation caused by Neoniti and ProTaper instruments, using cone-beam computed tomography (CBCT) cross sections. Methods and Materials: This in vitro experimental study was performed on 40 mesiobuccal roots of maxillary first molars. The teeth were scanned with CBCT. They were randomly divided into 2 groups (n=20) that were prepared using either Neoniti or ProTaper files. An endodontist prepared the canal according to the manufacturer’s guidelines. Prepared canals were re-scanned. The pre-instrumentation and post-instrumentation CBCT volumes were sectioned at 1 to 9-mm distances from the apex. The extent of canal dentine removal in mesial and distal directions were measured in each cross-section. Canal transportation and instrument centering ability were estimated based on the extents of root wall removal and were compared in both groups. Results: The groups were rather similar in terms of transportation and centering ability (P>0.05). However, canal preparation on mesial and distal walls was statistically significantly less in the Neoniti group, at most cross-sections. Transportation of both groups was not significantly different (P>0.05). Centering ability of both instruments was not significantly different (P>0.05). Conclusion: Neoniti and ProTaper instruments might have proper centering ability and minimum transportations. Both instruments might cause similar extents of transportation and centering abilities.Keywords: Centering Ability; Nickel Titanium Instruments; Root Canal Treatment; Root Canal Preparation; Transportatio

The Relationship between Ethical Climate and Organizational Citizenship Behavior of Nurses in Selected Hospitals Affiliated to Shahid Beheshti University of Medical Sciences

Background & Objectives: Ethical values act as the most powerful factors influencing citizenship behaviors. This research was conducted to investigate the relationship between ethical climate and organizational citizenship behavior in nurses of hospitals affiliated to Shahid Beheshti University of Medical Sciences. Methods: This descriptive-analytical study was performed on 307 nurses selected through random sampling in 2016. Data gathering tools were two questionnaires of ethical climate and organizational citizenship behavior. Data analysis was done through SPSS20 and using descriptive statistics, t-test, One- Way ANOVA, correlation and multiple regression tests. Results: Mean scores of ethical climate and citizenship behavior were respectively 3.51 ±0.55 and 3.49 ± 0.45 that reflects the favorable view of nurses towards ethical climate and citizenship behavior. Head nurses had the highest mean scores in the dimensions of ethical climate. Among the dimensions of citizenship behavior, the dimension of conscience gained the highest mean score among nurses. There was a significant relationship between employment status and ethical climate (P<0.001) and also a positive and significant correlation between ethical climate and citizenship behavior (P<.0.001). Conclusion: Promotion of ethical climate enables nurses to respond better to ethical stress, to adapt to other causes of workplace dissatisfaction and consequently showing citizenship behaviors. Some meetings are required to be held in order to improve the relationship between physicians and nurses, to create alignment and understanding among staff and consequently to improve citizen behaviors. Key­words: Ethical climate, Organizational citizenship behavior, Nurses, Teaching hospital ­Citation: Zarei E, Damiri S, Bagheri A, Fazli Ouchhesar F. The Relationship between Ethical Climate and Organizational Citizenship Behavior of Nurses in Selected Hospitals Affiliated to Shahid Beheshti University of Medical Sciences. Journal of Health Based Research 2019; 5(2): 175-186. [In Persian

The role of metalloproteinase and hypoxia conditions in endometrial cells and embryo implantation

In the process of implantation, metalloproteinase enzymes play a key role in basement membrane degradation and endometrial extracellular matrix. The activity of these enzymes is impeded by binding Tissue Inhibitors of Metalloproteinase (TIMP). The oxygen concentration in the mammalian uterus at the time of implantation is about 2-5%. It is seen that the imposition of hypoxia on cancer cells increases the expression of metalloproteinase enzymes and reduces the expression of metalloproteinase inhibitors, resulting in increased cell invasion. To know the effect of Hypoxia-Inducible Factor (HIF) and other related factors, we decided to evaluate hypoxic conditions on endometrial epithelial cells of the uterus and roll of matrix metalloproteinases (MMPs) on angiogenesis and invasion of the embryo during implantation. In this study, human and mouse endometrial epithelial cells were incubated for 24-48 hours in hypoxic conditions. Subsequently, the expression level of TIMP-1 was measured in mouse and human epithelial cells by Real-Time PCR technique. The cell viability in hypoxic conditions was evaluated by MTT assay. Our results demonstrated that hypoxia reduced the quantitative gene expression of TIMP-1 in the human and mouse endometrial epithelial cells compared to the control group. It can be concluded that applying hypoxic conditions by reducing the TIMP-1 expression and consequently increasing MMP expression, may improve the embryo implantation rate