Virtual Reality (VR) is an emerging technique that provides immersive experience for users. Due to the high computation cost of rendering real-time animation twice (for both eyes) and the resource limitation of wearable devices, VR applications often face performance bottlenecks and performanceoptimization plays an important role in VR software develop-ment. Performance optimizations of VR applications can be very different from those in traditional software as VR involves more elements such as graphics rendering and real-time animation. In this paper, we present the first empirical study on 183 real-world performance optimizations from 45 VR software projects. In particular, we manually categorized the optimizations in to 11 categories, and applied static analysis to identify how they affect different life-cycle phases of VR applications. Furthermore, we studied the complexity and design / behavior effects of performance optimizations, and how optimizations are different between large organizational software projects and smaller personal software projects. Our major findings include: (1) graphics simplification (24.0%), rendering optimization (16.9%), language / API optimization (15.3%), heap avoidance (14.8%), and valuecaching (12.0%) are the most common categories of performance optimization in VR applications; (2) game logic updates (30.4%) and before-scene initialization (20.0%) are the most common life-cycle phases affected by performance issues; (3) 45.9% of the optimizations have behavior and design effects and 39.3% of the optimizations are systematic changes; (4) the distributionsof optimization classes are very different between organizational VR projects and personal VR projects.

Data Mining is the process of finding pattern or useful information from large volume of data. The goal of this paper is to find the reason behind the unusual high birth rate by applying data mining techniques, e.g., decision tree, neural network, Bayes Classifier, Ripper and Support Vector Machine. The datasets were collected from the baseline survey conducted by the maternal neonatal and child health programme by ICDDR,B. If we could find the reason(s), high birth rate at home could be avoided in future. Giving birth at home is very dangerous as many complications may arise during pregnancy as well during birth. From the opinions of experts and professionals, it could be said that the risk of mortality of new born during home birth is quite alarming and birth at hospital/clinics seemed to be the safest place to protect the health and well-being of the woman and her baby.