Covariant formulations of BSSN and the standard gauge

The BSSN and standard gauge equations are written in covariant form with respect to spatial coordinate transformations. The BSSN variables are defined as tensors with no density weights. This allows us to evolve a given set of initial data using two different coordinate systems and to relate the results using the familiar tensor transformation rules. Two variants of the covariant equations are considered. These differ from one another in the way that the determinant of the conformal metric is evolved.Comment: 6 pages, no figures. Notation has been improved and typos have been correcte

Effect of laboratory heat stress on mortality and web mass of the common house spider, Parasteatoda tepidariorum (Koch 1841) (Araneae: Theridiidae)

We determined the effects of chronic heat stress on web construction of Parasteatoda tepidariorum (Araneae: Theridiidae) by measuring the survival and web mass of specimens after a 48-h period within a temperature chamber at 21, 30, 35, 40, or 50°C. The 21, 30 and 35°C treatments had the highest mean survival rate (100%), the 50°C treatment had the lowest (0%), and the 40°C treatment was intermediate (58%). The 21, 30, and 35°C treatments had the highest mean web mass, and the 40 and 50°C treatments had the lowest. Web mass did not correlate with spider mass for specimens across all temperature treatments. While acclimation temperature and humidity fluctuated throughout the 3 weeks of the study, neither variable affected web mass. This study demonstrates the sublethal effect of temperature on web construction, an effect that would ultimately be lethal in nature if a spider was unable to construct its web

Facilitating open plot structures in story driven video games using situation generation

Story driven video games are rising in popularity, along with the players desire to make meaningful choice within the plot and therefore become more involved and immersed within the experience. This paper investigates the problems which arise from implementing interactive narrative within video games and potential techniques to solve those problems. The main focus of the study was the situation generation technique, used to maintain the continuity within open, emergent plot structures, using behaviour trees as a means to implement and traverse plot sequences. The ISGEngine was developed during the course of this study in order to implement and evaluate the situation generation technique

Competition and Firm Performance: Lessons from Russia

D24, D4, J42, L1, L33, P23, P31The "big-bang" liberalization of the inefficient Russian economy in 1992 provides a fruitful setting for analyzing the impact of several dimensions of market competition and other factors on enterprise efficiency. We analyze 1992-1998 panel data on 14,961 enterprises covering 75 percent of industrial employment, emphasizing the varied sources, geographic scope, intensity, time path, and survival effects of competitive pressures. We find large, positive effects on TFP from competition in domestic product and local labor markets, and from imports and better transportation infrastructure, although the first effect appears only gradually. Non-state firms outperform state enterprises, even after correction for selection bias.http://deepblue.lib.umich.edu/bitstream/2027.42/39680/3/wp296.pd