Language & Video Games: A Cross-Genre Approach

Online multiplayer games are often thought to promote "toxic" or negative language due to their competitive nature and need for cooperation from teammates. This study will investigate language patterns of players from different genres and aims to provide insight on how game characteristics may influence general language use in online communities.Psycholog

On the growth and velocity effects of money

We show that a one-sector AK model of endogenous growth with the most generalized cash-in-advance constraint is able to account for (i) the observed long-run negative relationship between the nominal growth rate of money and the income velocity of money, (ii) the empirically ambiguous effect of changing inflation on the economy's output growth, and (iii) the divergent growth experience of countries that start with similar macroeconomic conditions.

Effects of duration of selected music as an intervention on postoperative pain in open-heart surgery patients during chair rest on the first postoperative day

The purpose of this study was to test the effects of selected music on reducing postoperative pain and use of pain relief medications in open-heart surgery patients during chair rest on the first postoperative day. This study was conducted using a pretest-posttest experimental design. A convenience sample of 13 open-heart surgery patients from a metropolitan hospital in southeastern Michigan were randomly assigned to the music group (n = 6) and the control group (n = 7). T-test analysis showed that pain scores (numeric rating scale, NRS = 0-10) were lower in the music group than the control group after 30, 45, and 60 minutes of chair rest, and sense of well-being rated by using the visual analog scale (VAS = 0-100) was also higher in the music group at 60 minutes than the control group although the difference was not statistically significant. Optimal duration of music to reduce postoperative pain and the frequency of the use of pain medication could not be determined due to the small sample size. A replication study with a larger study group is recommended to ensure greater statistical power to test the usefulness of music as an adjuvant therapy in reducing postoperative pain

Algorithms for spacecraft formation flying navigation based on wireless positioning system measurements

Spacecraft formation flying navigation continues to receive a great deal of interest. The research presented in this dissertation focuses on developing methods for estimating spacecraft absolute and relative positions, assuming measurements of only relative positions using wireless sensors. The implementation of the extended Kalman filter to the spacecraft formation navigation problem results in high estimation errors and instabilities in state estimation at times. This is due tp the high nonlinearities in the system dynamic model. Several approaches are attempted in this dissertation aiming at increasing the estimation stability and improving the estimation accuracy. A differential geometric filter is implemented for spacecraft positions estimation. The differential geometric filter avoids the linearization step (which is always carried out in the extended Kalman filter) through a mathematical transformation that converts the nonlinear system into a linear system. A linear estimator is designed in the linear domain, and then transformed back to the physical domain. This approach demonstrated better estimation stability for spacecraft formation positions estimation, as detailed in this dissertation. The constrained Kalman filter is also implemented for spacecraft formation flying absolute positions estimation. The orbital motion of a spacecraft is characterized by two range extrema (perigee and apogee). At the extremum, the rate of change of a spacecraft’s range vanishes. This motion constraint can be used to improve the position estimation accuracy. The application of the constrained Kalman filter at only two points in the orbit causes filter instability. Two variables are introduced into the constrained Kalman filter to maintain the stability and improve the estimation accuracy. An extended Kalman filter is implemented as a benchmark for comparison with the constrained Kalman filter. Simulation results show that the constrained Kalman filter provides better estimation accuracy as compared with the extended Kalman filter. A Weighted Measurement Fusion Kalman Filter (WMFKF) is proposed in this dissertation. In wireless localizing sensors, a measurement error is proportional to the distance of the signal travels and sensor noise. In this proposed Weighted Measurement Fusion Kalman Filter, the signal traveling time delay is not modeled; however, each measurement is weighted based on the measured signal travel distance. The obtained estimation performance is compared to the standard Kalman filter in two scenarios. The first scenario assumes using a wireless local positioning system in a GPS denied environment. The second scenario assumes the availability of both the wireless local positioning system and GPS measurements. The simulation results show that the WMFKF has similar accuracy performance as the standard Kalman Filter (KF) in the GPS denied environment. However, the WMFKF maintains the position estimation error within its expected error boundary when the WLPS detection range limit is above 30km. In addition, the WMFKF has a better accuracy and stability performance when GPS is available. Also, the computational cost analysis shows that the WMFKF has less computational cost than the standard KF, and the WMFKF has higher ellipsoid error probable percentage than the standard Measurement Fusion method. A method to determine the relative attitudes between three spacecraft is developed. The method requires four direction measurements between the three spacecraft. The simulation results and covariance analysis show that the method’s error falls within a three sigma boundary without exhibiting any singularity issues. A study of the accuracy of the proposed method with respect to the shape of the spacecraft formation is also presented