Customizing Vehicular Ad Hoc Networks to Individual Drivers and Traffic Conditions

This dissertation studies the ability to individualize vehicular ad hoc networks (VANETs) in order to improve safety. Adapting a VANET to both its individual drivers\u27 characteristics and traffic conditions enables it to transmit in a smart manner to other vehicles. This improvement is now possible due to the progress that is being made in VANETs. To accomplish this adaptation, our approach is to use VANET data to learn drivers\u27 characteristics. This information along with the traffic data, can be used to customize the VANETs to individual drivers. In this dissertation, we show that this process benefits all the drivers by reducing the collision probability of the network of vehicles. Our Monte Carlo simulation results show that this approach achieves more than 25% reduction in traffic collision probability compared to the case with optimized equal vehicular communication access for each vehicle. Therefore, it has a considerable advantage over other systems. First, we propose a method to estimate the distribution of a driver\u27s characteristics by employing the VANET data. This is essential for our intended application in accident warning systems and vehicular communications. Second, this estimated distribution and the traffic information are used to adapt the transmission rates of vehicles to each driver\u27s safety level in order to reduce the number of collisions in the network. We derive the packet success probability for a chain of vehicles by taking multi-user interference, path loss, and fading into account. Then, by considering the delay constraints and types of potential collisions, we approximate the required channel access probabilities and illustrate the collision probability. Third, since the packet success probability and thus communication interference affect the collision probability noticeably, we examine various interference models and their effect on the collision probability with more scrutiny. In our analysis, two signal propagation models with and without carrier sensing are considered for the dissemination of periodic safety messages, and it is illustrated how employing more accurate interference models results in a higher level of safety (lower collision probability)for the network. Finally, there is an unclear relation between the intensity of an ad hoc network (the number of vehicles in a certain area) and the performance of the system. Hence, we study a reverse approach in which the geometry (intensity) of the unmanned aerial vehicles varies and certain requirements such as safety and coverage need to be satisfied. The numerical results show that safety and interference limits the coverage of the network and there is only a relatively small range of intensities which satisfy all three

Real-Time Estimation of the Distribution of Brake Response Times for an Individual Driver Using Vehicular Ad Hoc Network

Adapting the functioning of the collision warning systems to the specific drivers' characteristics is of great benefit to drivers. For example, by customizing collision warning algorithms we can minimize false alarms, thereby reducing injuries and deaths in highway traffic accidents. In order to take the behaviors of individual drivers into account, the system needs to have a Real-Time estimation of the distribution of brake response times for an individual driver. In this paper, we propose a method for doing this estimation which is not computationally intensive and can take advantage of the information contained in all data points

An Investigation of the Relationship between Thematic Thinking and Innovative Work Behavior among Managers: The Mediating Role of Open-mindedness

There exists empirical evidence that thematic thinking through the mediation of innovativeness impacts employee performance. We, in an explorative manner, went further to understand the underlying mechanism which promotes innovative work-related behavior. We collected data from individuals at R&D assignments of various organizations where new ideas and products are developed. A total of 295 survey forms were collected, and the analysis was done using the PROCESS Macro for SPSS in order to test the mediation model. The results revealed that thematic thinking was positively linked to open-mindedness and innovative work behavior; also open-mindedness mediated the relationship between thematic thinking and innovative work behavior. This study has explored, tested, and empirically proved a novel relation in the local context of R&D related individuals (managers) working in diverse fields. The current research extends thematic thinking in the domain of cognition, innovation, and workplace behavior. It concludes that managerial decision making is elemental in performing innovatively. Practical and managerial implications, limitations, and future research directions are discussed to enrich the domain of thematic similarity further

An Investigation of the Relationship between Thematic Thinking and Innovative Work Behavior among Managers: The Mediating Role of Open-mindedness

There exists empirical evidence that thematic thinking through the mediation of innovativeness impacts employee performance. We, in an explorative manner, went further to understand the underlying mechanism which promotes innovative work-related behavior. We collected data from individuals at R&D assignments of various organizations where new ideas and products are developed. A total of 295 survey forms were collected, and the analysis was done using the PROCESS Macro for SPSS in order to test the mediation model. The results revealed that thematic thinking was positively linked to open-mindedness and innovative work behavior; also open-mindedness mediated the relationship between thematic thinking and innovative work behavior. This study has explored, tested, and empirically proved a novel relation in the local context of R&D related individuals (managers) working in diverse fields. The current research extends thematic thinking in the domain of cognition, innovation, and workplace behavior. It concludes that managerial decision making is elemental in performing innovatively. Practical and managerial implications, limitations, and future research directions are discussed to enrich the domain of thematic similarity further

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

Development of leukocytoclastic vasculitis during long-term methotrexate therapy in patients with rheumatoid arthritis: description of two clinical cases

Leukocytoclastic vasculitis (LCV) is a small vessel vasculitis characterized by immune complex depositions involving dermal post-capillary venules. Cutaneous small vessel vasculitis is most often idiopathic but may be aggravated by secondary causes, such as inflammatory conditions, infections, neoplasms, and drugs exposure.Herein, we describe two patients with a long history of rheumatoid arthritis (RA) treated with methotrexate (MTX) for more than ten years, who later developed generalized LCV with pancytopenia after a viral infection, one with herpes simplex virus, and the other with SARS-CoV-2 virus. Because of the worldwide use of MTX in treatment of RA, strict follow-up and preventive measures are needed nowadays, especially during COVID-19 pandemic, in order to avoid any infection which may provoke LCV with or without systemic manifestations. So, using MTX for treating RA or other similar disorders may be considered a double-edged sword, especially during COVID-19 pandemic.

Metastasis of femoral osteosarcoma to the abdominal wall detected on 99m Tc-MDP skeletal scintigraphy

Osteosarcoma is the most frequent primary malignancy of bone, and usually metastasizes to the lung and bones, while other sites are rare. In most reported cases, soft tissue metastasis of osteosarcoma is unusual, and only develops in the advanced stages of the disease, especially following multiple recurrences. We present a patient with recently diagnosed osteosarcoma of the right femur, showing abdominal wall metastasis diagnosed by technetium-99m-methylene diphosphonate (99m Tc-MDP) whole body bone scintigraphy and confirmed histologically. The present case highlights the importance of whole body imaging of patients with osteosarcoma for detecting unusual sites of metastasis, especially in soft tissue organs