Comparing the performance of IBIS and BulletTRAX-3D technology using bullets fired through 10 consecutively rifled barrels

This study evaluates the abilities of the Integrated Ballistics Identification System (IBIS) and BulletTRAX-3D electronic imaging systems to identify bullets fired by the same weapon in a large database of images. Ten consecutively rifled handgun barrels were test fired to obtain reference sample and known match sample pairs for upload onto both bullet acquisition systems. Both copper-jacketed and lead bullets were uploaded, to account for variations in the manner in which markings are reproduced on the different metal compositions. Ranked correlation lists were examined and evaluated. For copper-jacketed bullet correlations, both IBIS and BulletTRAX-3D identified all reference samples to their known matches within the top 10 positions. For lead bullets, BulletTRAX-3D identified all reference samples to their known match in the top 10 positions while IBIS identified only 30%. For inter composition comparisons, BulletTRAX-3D was more successful than IBIS, identifying 100% of reference samples to their known match in the top 20 for copper-jacketed to lead comparisons and 90% for lead to copper-jacketed comparisons. These results suggest that BulletTRAX-3D is more effective than IBIS in the analysis of a wider range of bullet types and it was also found to produce images of superior quality.     

Sex-Based Occupational Segregation in U.S. State Bureaucracies, 1987–97

Is the extent of sex-based occupational segregation in U.S. state bureaucracies related to agency policy missions? Drawing on arguments by Lowi (1985), we contend that levels of sex-based occupational segregation in state bureaucracies vary depending on whether an agency's policy mission is distributive, regulatory, or redistributive. We employ data on the distribution of administrative and professional employees by sex in several types of state agencies across all 50 states for 1987–97. Our findings indicate high levels of occupational segregation among administrative cadres in agencies with distributive and regulatory policy commitments; however, professional workforces in these agencies have become less gender segregated over time. We find no evidence of occupational segregation among administrative and professional workforces in redistributive agencies. We argue that researchers need to examine the relationship between glass walls and other kinds of sex-based employment impediments, such as glass ceilings.