Metal objects mapping after small charge explosions. A study on AISI 304Cu steel with two different grain sizes

Evidence of exposure of a metal component to a small charge explosion can be detected by observing microstructural modifications; they may be present even if the piece does not show noticeable overall plastic deformations. Particularly, if an austenitic stainless steel (or another metal having a face-centered cubic structure and a low stacking fault energy) is exposed to an explosive shock wave, high-speed deformation induces primarily mechanical twinning, whereas, in nonexplosive events, a lower velocity plastic deformation first induces slip. The occurrence of mechanical twins can be detected even if the surface is damaged or oxidized in successive events. In the present research, optical metallography (OM) and scanning electron microscopy (SEM), and scanning tunneling microscopy (STM) were used to detect microstructural modifications caused on AISI 304Cu steel disks by small-charge explosions. Spherical charges of 54.5 or 109 g TNT equivalent mass were used at explosive-to-target distances from 6.5 to 81.5 cm, achieving peak pressures from 160 to 0.5 MPa. Explosions induced limited or no macro-deformation. Two alloy grain sizes were tested. Surface OM and SEM evidenced partial surface melting, zones with recrystallization phenomena, and intense mechanical twinning, which was also detected by STM and X-ray diffraction. In the samples' interior, only twins were seen, up to some distance from the explosion impinged surface and again, at the shortest charge-to-sample distances, in a thin layer around the reflecting surface. For forensic science locating purposes after explosions, the maximum charge-to-target distance at which the phenomena disappear was singled out for each charge or grain size and related to the critical resolved shear stress for twinning.     

Correlates Of Cynicism: The Case For Black Police Officers

In this paper we test the relationship between perceived satisfaction with promotion policy and cynical attitudes for fifty-seven black male officers in a southern metropolitan police department. Correlation analyses revealed that selected variables taken from the Niederhoffer (1967) model relate to feelings of mistrust in hypothesized directions. Satisfaction with promotion policy was observed to be the most important predictor of cynicism after controlling for the effects of rank, years of service, and education. Equity motivation theory is then presented as an approach to modify traditional opportunity structures grounded in politics and seniority.     

Toward Good Governance and Sustainable Development: The African Peer Review Mechanism

To accomplish the objectives and the outcomes of the New Partnership for Africa's Development (NEPAD), African leaders have agreed, among other things, to subject their countries to peer review through the use of a unique and innovative African Peer Review Mechanism (APRM). This paper analytically describes and assesses the APRM. It contends that peer review represents a sea of change in the thinking of African leaders as they seek to reverse the trend of lack of accountability, political authoritarianism, state failure, and corruption to embrace and consolidate democracy as well as effect sound and transparent economic management. It is further argued that peer review would provide a number of benefits to those countries that subject themselves to it and that, in turn, would have positive multiplier effects on Africa's development performance.     

Measuring Children's Suggestibility in Forensic Interviews

According to the scientific literature, childrens’ cognitive development is not complete until adolescence. Therefore, the problems inherent in children serving as witnesses are crucial. In preschool‐aged children, false memories may be identified because of misinformation and insight bias. Additionally, they are susceptible of suggestions. The aim of this study was to verify the levels of suggestibility in children between three and 5 years of age. Ninety‐two children were examined (44 male, 48 female; M = 4.5 years, SD = 9.62). We used the correlation coefficient (Pearson's r) and the averages variance by SPSS statistical program. The results concluded that: younger children are almost always more susceptible to suggestibility. The dimension of immediate recall was negatively correlates with that of total suggestibility (r = ?0.357 p < 0.001). Social compliance and source monitoring errors contribute to patterns of suggestibility, because older children shift their answers more often (r = 0.394 p < 0.001). Younger children change their answers more times (r = ?0.395 p < 0.001).