Star Formation and Relaxation in 379 Nearby Galaxy Clusters

We investigate the relationship between star formation (SF) and level of relaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the Sloan Digital Sky Survey to measure cluster membership and level of relaxation, and to select star-forming galaxies based on mid-infrared emission detected with the Wide-Field Infrared Survey Explorer. For galaxies with absolute magnitudes M_r < -19.5, we find an inverse correlation between SF fraction and cluster relaxation: as a cluster becomes less relaxed, its SF fraction increases. Furthermore, in general, the subtracted SF fraction in all unrelaxed clusters (0.117 +/- 0.003) is higher than that in all relaxed clusters (0.097 +/- 0.005). We verify the validity of our SF calculation methods and membership criteria through analysis of previous work. Our results agree with previous findings that a weak correlation exists between cluster SF and dynamical state, possibly because unrelaxed clusters are less evolved relative to relaxed clusters.Comment: 6 pages, 4 figures, accepted for publication in Ap

Criminal Procedure—MIranda: the Application of the Fifth Amendment Right Against Self-Incrimination to Confessions—A Change in Approach.

Miranda v. Arizona (consolidated in a single opinion with three companion cases, Vignera v. New York, Westover v. United States and California v. Stewart), 384 U.S. 436 (1966)

Strategic Competition Over School Inputs and Outputs

Although public schools are not generally subject to direct competition for students, it is commonly thought that they nonetheless face competition through parents\u27 residential choice. Such competitive effects are likely to depend on the relative proximity of school districts if it is less costly to move short distances than long, or if parents are able to more easily send their children to nearby districts through open enrollment policies. Using panel data for 607 Ohio school districts from 1998 to 2007, I test for strategic interaction over teacher salaries and standardized test scores. I present evidence that Ohio public school districts act to \u27follow their neighbors\u27- that is, that they attempt to exactly mirror changes in the inputs and outputs of nearby school districts and I show that this result is robust to different definitions of \u27neighbor.\u27 I further show that conventional estimation of spatial autoregressive models via Maximum Likelihood or via poorly-instrumented General Method of Moments may create large biases in the estimated spatial autocorrelation coefficient. I suggest that this statistical phenomenon may explain some of the differences in estimated magnitudes of school competition across the spatial literature

Strategic Competition Over School Inputs and Outputs

Although public schools are not generally subject to direct competition for students, it is commonly thought that they nonetheless face competition through parents\u27 residential choice. Such competitive effects are likely to depend on the relative proximity of school districts if it is less costly to move short distances than long, or if parents are able to more easily send their children to nearby districts through open enrollment policies. Using panel data for 607 Ohio school districts from 1998 to 2007, I test for strategic interaction over teacher salaries and standardized test scores. I present evidence that Ohio public school districts act to \u27follow their neighbors\u27- that is, that they attempt to exactly mirror changes in the inputs and outputs of nearby school districts and I show that this result is robust to different definitions of \u27neighbor.\u27 I further show that conventional estimation of spatial autoregressive models via Maximum Likelihood or via poorly-instrumented General Method of Moments may create large biases in the estimated spatial autocorrelation coefficient. I suggest that this statistical phenomenon may explain some of the differences in estimated magnitudes of school competition across the spatial literature