Acceptance of feedbacks in reputation systems: the role of online social interactions

In an online environment, the aim of reputation systems is to let parties rate each other and to help consumers in deciding whether to transact with a given party. In current reputation systems for e-commerce, users have to trust unreliable information sources and anonymous people. As a result, users are not only hesitant to trust online seller but also to reputation systems. Therefore, there is a need to improve current reputation systems by allowing users to make buying decision based on reliable source of information. This paper proposes a new approach of sharing knowledge and experience in reputation systems by utilizing social interactions. This study examines the potentials of integrating social relations information in reputation systems by proposing a model of acceptance of feedbacks in reputation systems

Resource Allocation in Vehicular Cloud Computing

Recently, we have witnessed the emergence of Cloud Computing, a paradigm shift adopted by information technology (IT) companies with a large installed infrastructure base that often goes under-utilized. The unmistakable appeal of cloud computing is that it provides scalable access to computing resources and to a multitude of IT services. Cloud computing and cloud IT services have seen and continue to see a phenomenal adoption rate around the world. Recently, Professor Olariu and his coworkers through series of research introduced a new concept, Vehicular Cloud Computing. A Vehicular Cloud (VC) is a network of vehicles in a parking lot that can provide computation services to users. In this model each vehicle is a computation node. Some of the applications of a VC include a datacenter at the airport, a data cloud in a parking lot, and a datacenter at the mall. The defining difference between vehicular and conventional clouds lies in the distributed ownership and, consequently, the unpredictable availability of computational resources. As cars enter and leave the parking lot, new computational resources become available while others depart, creating a dynamic environment where the task of efficiently assigning jobs to cars becomes very challenging. Our main contribution is a number of scheduling and fault-tolerant job assignment strategies, based on redundancy, that mitigate the effect of resource volatility in vehicular clouds. We offer a theoretical analysis of the expected job completion time in the case where cars do not leave during a checkpoint operation and also in the case where cars may leave while checkpointing is in progress, leading to system failure. A comprehensive set of simulations have shown that our theoretical predictions are accurate. We considered two different environments for scheduling strategy: deterministic and stochastic. In a deterministic environment the arrival and departure of cars are known. This scenario is for environments like universities where employees should be present at work with known schedules and the university rents out its employees\u27 cars as computation nodes to provide services as a vehicular cloud. We presented a scheduling model for a vehicular cloud based on mixed integer linear programming. This work investigates a job scheduling problem involving non-preemptive tasks with known processing time where job migration is allowed. Assigning a job to resources is valid if the job has been executed fully and continuously (no interruption). A job cannot be executed in parallel. In our approach, the determination of an optimal job schedule can be formulated as maximizing the utilization of VC and minimizing the number of job migrations. Utilization can be calculated as a time period that vehicles have been used as computation resources. For dynamic environment in terms of resource availability, we presented a stochastic model for job assignment. We proposed to make job assignment in VC fault tolerant by using a variant of the checkpointing strategy. Rather than saving the state of the computation, at regular times, the state of the computation is only recorded as needed. Also, since we do not assume a central server that stores checkpointed images, like conventional cloud providers do, in our strategy checkpointing is performed by a car and the resulting image is stored by the car itself. Once the car leaves, the image is lost. We consider two scenarios: in the first one, cars do not leave during checkpointing; in the second one, cars may leave during checkpointing, leading to system failure. Our main contribution is to offer theoretical predictions of the job execution time in both scenarios mentioned above. A comprehensive set of simulations have shown that our theoretical predictions are accurate

Comparison of Health Literacy among Academic Librarians. Case Study: Tehran of Medical Sciences and Azad Universities Librarians

Objective: Promoting health and determining the level of health literacy is one of the most important indicators in each society. This study was conducted with the aim of evaluating the health literacy status among librarians of Azad universities and medical sciences regarding the impact of librarians on their individual health and their role in disseminating health information that promotes health. This research is a descriptive survey. The statistical population consists of 90 librarians working in the libraries of the Islamic Azad universities and medical sciences in Tehran. The data were collected using TOFHLA\u27s functional health literacy questionnaire in December 2018 Descriptive statistics, one-way T-test and Friedman test were used to analyze the data. The mean age of the subjects was 39, of which 74.7% were women and the rest were male, and 69% had a library education. The mean health literacy score was 83.7%. 82.3% of librarians had adequate health literacy, 3.8% had border health literacy and 13.9% had inadequate health literacy. The health literacy of librarians in two universities was sufficient and not significant. Conclusion: Since there was no significant difference between the health literacy of librarians of the two universities, the activity in medical science libraries was not very effective in achieving health literacy

Understanding Cell Viability And Mechanics Of Actin Filament Response Of Nih/3T3 Fibroblasts Under Biaxial Stretch

Cells are constantly subjected to mechanical stress during various physical activities. Understanding the role of the resultant mechanical stresses on cellular mechanotransduction is critical for considerate various cellular activities in the body such as control of cell growth, migration, differentiation, apoptosis and wound repair. The long-term goal is to understand whether it is possible to control cell functions through mechanical forces. Specifically, in this work, we report on the cellular and mechanistic response of NIH/3T3 fibroblastic cells (cultured on silicone membrane), when subjected to cyclic biaxial stretch generated in a custom-built stretching system, as described in Karumbaiah et al (Karumbaiah et al., 2012). The silicone membrane was first plasma-treated to increase its hydrophilicity, followed by coating a layer of Collagen type-I to increase cell adhesion to the membrane. Cell viability and morphological changes at the cell surface were studied in response to cyclic biaxial forces to determine the effect of time and amplitude on cell responses. In particular, the cell responses have been studied at 5% up to 10% strain with keeping frequency constant as low as 0.05 cycles/sec along with variable stretching time (6 and 24 hours) to model a situation closer to in vivo. Our results indicate that stretching cells under applied conditions have no considerable negative effect on cells viability while significantly increase the proliferation of cells. Also, there is a migration happened for cells from inner parts of the membrane to the corners which might be a result of the combination of shear stress (resulted from liquid movements during stretch) and the localized bending stress at the range of bending forces (when the membrane bends over glass indenters). Additionally, there is no evidence of alignment of the actin filament of cells under biaxial force whereas the spreading factor which is an indication of actin filament’s response to the cell’s mechanical environment was increased for stretched samples compared to the control

Towards Dynamic Vehicular Clouds

Motivated by the success of the conventional cloud computing, Vehicular Clouds were introduced as a group of vehicles whose corporate computing, sensing, communication, and physical resources can be coordinated and dynamically allocated to authorized users. One of the attributes that set Vehicular Clouds apart from conventional clouds is resource volatility. As vehicles enter and leave the cloud, new computing resources become available while others depart, creating a volatile environment where the task of reasoning about fundamental performance metrics becomes very challenging. The goal of this thesis is to design an architecture and model for a dynamic Vehicular Cloud built on top of moving vehicles on highways. We present our envisioned architecture for dynamic Vehicular Cloud, consisting of vehicles moving on the highways and multiple communication stations installed along the highway, and investigate the feasibility of such systems. The dynamic Vehicular Cloud is based on two-way communications between vehicles and the stations. We provide a communication protocol for vehicle-to-infrastructure communications enabling a dynamic Vehicular Cloud. We explain the structure of the proposed protocol in detail and then provide analytical predictions and simulation results to investigate the accuracy of our design and predictions. Just as in conventional clouds, job completion time ranks high among the fundamental quantitative performance figures of merit. In general, predicting job completion time requires full knowledge of the probability distributions of the intervening random variables. More often than not, however, the data center manager does not know these distribution functions. Instead, using accumulated empirical data, she may be able to estimate the first moments of these random variables. Yet, getting a handle on the expected job completion time is a very important problem that must be addressed. With this in mind, another contribution of this thesis is to offer easy-to-compute approximations of job completion time in a dynamic Vehicular Cloud involving vehicles on a highway. We assume estimates of the first moment of the time it takes the job to execute without any overhead attributable to the working of the Vehicular Cloud. A comprehensive set of simulations have shown that our approximations are very accurate. As mentioned, a major difference between the conventional cloud and the Vehicular Cloud is the availability of the computational nodes. The vehicles, which are the Vehicular Cloud\u27s computational resources, arrive and depart at random times, and as a result, this characteristic may cause failure in executing jobs and interruptions in the ongoing services. To handle these interruptions, once a vehicle is ready to leave the Vehicular Cloud, if the vehicle is running a job, the job and all intermediate data stored by the departing vehicle must be migrated to an available vehicle in the Vehicular Cloud

A study on the first-passage reliability problem and its application in earthquake engineering

The research presented in this thesis focuses on analytical approximations for the time-variant first-passage failure probability (FPFP) of linear elastic models of structural systems subjected to stochastic excitations. The FPFP is defined as the probability that a response quantity of an engineering system subjected to a dynamic stochastic loading outcrosses a specified threshold within a given exposure time. The FPFP is an important and useful quantity for many structural engineering applications. The classical first-passage reliability problem is studied for linear elastic single-degree-of-freedom (SDOF) and multi-degrees-of-freedom (MDOF) systems subjected to stationary and nonstationary Gaussian excitations. The absolute and relative accuracy of several analytical approximations available in the literature (i.e., the Poisson’s (P), classical Vanmarcke’s (cVM), and modified Vanmarcke’s (mVM) approximations) are studied through an extensive parametric study for SDOF systems. In addition, a new analytical approximation for the FPFP of linear SDOF systems is developed. The new proposed approximation is verified by comparing its analytical estimates of the failure probability with the corresponding results obtained using existing analytical approximations and the importance sampling using elementary events (ISEE) method for a wide range of oscillator properties and different types of input excitations. It is found that the newly developed analytical approximation provides estimates of the time-variant FPFP of SDOF systems that are significantly more accurate than the estimates obtained using the P, cVM, and mVM approximations. Real-valued and complex-valued modal analysis with modal truncation is used to study the time-variant FPFP of MDOF subjected to stationary and nonstationary stochastic excitations. The absolute and relative accuracy of the P, cVM, and mVM approximations as well as of the newly developed approximation are studied for a select number of case studies. It is found that the newly proposed analytical approximation cannot be directly extended to the computation of the FPFP of MDOF systems, while the mVM approximation appears to be more accurate than the other existing analytical approximations

Understanding Cell Viability And Mechanics Of Actin Filament Response Of Nih/3T3 Fibroblasts Under Biaxial Stretch

Cells are constantly subjected to mechanical stress during various physical activities. Understanding the role of the resultant mechanical stresses on cellular mechanotransduction is critical for considerate various cellular activities in the body such as control of cell growth, migration, differentiation, apoptosis and wound repair. The long-term goal is to understand whether it is possible to control cell functions through mechanical forces. Specifically, in this work, we report on the cellular and mechanistic response of NIH/3T3 fibroblastic cells (cultured on silicone membrane), when subjected to cyclic biaxial stretch generated in a custom-built stretching system, as described in Karumbaiah et al (Karumbaiah et al., 2012). The silicone membrane was first plasma-treated to increase its hydrophilicity, followed by coating a layer of Collagen type-I to increase cell adhesion to the membrane. Cell viability and morphological changes at the cell surface were studied in response to cyclic biaxial forces to determine the effect of time and amplitude on cell responses. In particular, the cell responses have been studied at 5% up to 10% strain with keeping frequency constant as low as 0.05 cycles/sec along with variable stretching time (6 and 24 hours) to model a situation closer to in vivo. Our results indicate that stretching cells under applied conditions have no considerable negative effect on cells viability while significantly increase the proliferation of cells. Also, there is a migration happened for cells from inner parts of the membrane to the corners which might be a result of the combination of shear stress (resulted from liquid movements during stretch) and the localized bending stress at the range of bending forces (when the membrane bends over glass indenters). Additionally, there is no evidence of alignment of the actin filament of cells under biaxial force whereas the spreading factor which is an indication of actin filament’s response to the cell’s mechanical environment was increased for stretched samples compared to the control