Simple Software Development Techniques for Wireless Network Simulator

Department of Computer EngineeringNetwork Simulators have been widely used in many uses of academic and educational areas. In advance of applying experimental simulation results to real world networks, it is important to verify their theoretical network performance and some of specific event routines through network simulators (ns-2, ns-3, OPNET, NetSim, etc.). If the test and verifying procedures are omitted, the system may cause some unexpected problems which can result in unreliability, unexpected maintenance costs and so on. Therefore, it is a common practice to demonstrate the performance of network prior to public release using software simulator. In this context, we focus on problems of the most renowned simulation package, ns-3. In the point of simulation development performance, the ns-3 uses some of unnecessary modules compared to a customized solution, in particular, for a small and simple network simulation. In this thesis, we define several problems and disadvantages of the ns-3, and present solutions and comparison results to solve high complexity problem of simulations and the accessibility of simulation source code to the beginners who are about to use the simulation for educational use: 1) we present a simple software development techniques which reduce the development times and the number of needless module in C++ objected-oriented programming environment; As the other way to implement a simple discrete network simulator, 2) we also present the simple network simulator development algorithm(SNSDA) that describes programming steps for discrete-event network simulator; Finally, we compare our simple development algorithm to the ns-3 in case of the most general IEEE 802.11 based wireless network scenario so that the SDA has some advantages in wireless network simulation.ope

PPM1A Controls Diabetic Gene Programming through Directly Dephosphorylating PPAR?? at Ser273

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a master regulator of adipose tissue biology. In obesity, phosphorylation of PPAR gamma at Ser273 (pSer273) by cyclin-dependent kinase 5 (CDK5)/extracellular signal-regulated kinase (ERK) orchestrates diabetic gene reprogramming via dysregulation of specific gene expression. Although many recent studies have focused on the development of non-classical agonist drugs that inhibit the phosphorylation of PPAR gamma at Ser273, the molecular mechanism of PPAR gamma dephosphorylation at Ser273 is not well characterized. Here, we report that protein phosphatase Mg2+/Mn2+-dependent 1A (PPM1A) is a novel PPAR gamma phosphatase that directly dephosphorylates Ser273 and restores diabetic gene expression which is dysregulated by pSer273. The expression of PPM1A significantly decreases in two models of insulin resistance: diet-induced obese (DIO) mice and db/db mice, in which it negatively correlates with pSer273. Transcriptomic analysis using microarray and genotype-tissue expression (GTEx) data in humans shows positive correlations between PPM1A and most of the genes that are dysregulated by pSer273. These findings suggest that PPM1A dephosphorylates PPAR gamma at Ser273 and represents a potential target for the treatment of obesity-linked metabolic disorders

Factors affecting customer intention to use online food delivery services before and during the COVID-19 pandemic

With the emerging popularity of online food delivery (OFD) services, this research examined predictors affecting customer intention to use OFD services amid the Coronavirus disease (COVID-19) pandemic. Specifically, Study 1 examined the moderating effect of the pandemic on the relationship between six predictors (perceived usefulness, perceived ease of use, price saving benefit, time saving benefit, food safety risk perception, and trust) and OFD usage intention, and Study 2 extended the model by adding customer perceptions of COVID-19 (perceived severity and vulnerability) during the pandemic. Study 1 showed that all of the predictors except food safety risk perception significantly affected OFD usage intention, but no moderation effect of COVID-19 was found. In Study 2, while perceived severity and vulnerability had no significant impact on OFD usage intention, the altered effects of socio-demographic variables during the COVID-19 pandemic were found. Theoretical and managerial implications are provided