This paper extends the stop and frisk literature from New York City by examining pedestrian stops made by San Jose, California, police officers from January 2013 through March 2016 with a particular focus on benchmarking. Using violent crime suspects and nuisance-related calls for service (CFS) as comparators, we consider whether San Jose Police Department (SJPD) officers disproportionately stopped individuals from the city’s dominant racial and ethnic groups citywide and in certain police beats with high levels of nuisance calls. Using violent crime suspects citywide as a benchmark, Whites were significantly overrepresented among those stopped by the police while Hispanics, Asians, and Blacks were underrepresented. The CFS findings at the beat level were consistent with the citywide findings for Blacks but reversed direction for Hispanics and varied for Asians depending upon beat and call type. We discuss possible reasons for this divergence across benchmarks and racial/ethnic groups and consider the implications for future research.
A comprehensive study of the nuclear spin-lattice relaxation in the hexagonal close packed phase of solid deuterium and the liquid is presented. All of the measurements covering the temperature range 2.S-20.3°K and for para concentration 2%-94% were carried out using a pulsed technique, the pulse sequence being saturation -T-90° at 8.0 MHz. It is shown that all of the experimental data can be accounted for on the basis of a kinetic model which assumes three principal relaxation mechanisms for the transfer of spin energy to the lattice from the two spin systems 1=1, J = 1 (para-D2) and 1=2, J =0 (ortho-D2). These are (1) the modulation of the intramolecular spin-spin interactions by the anisotropic electric quadrupolar intermolecular interactions which represents the most important process for the direct relaxation of para-D2, (2) the intermolecular spin-spin interaction modulated by the self-diffusion in the solid or liquid which represents the only direct process for relaxation of the ortho-D2, and (3) the adiabatic cross relaxation between the two spin systems, the indirect process for the relaxation of the ortho-D2 dependent on the extent of coupling between the two different spins. This varies from the extreme of strong coupling in the rigid solid, where the self-diffusion is negligible, to weak coupling in the high-temperature solid and liquid where thermal motion is significant. A quantitative explanation of the experimental results for the hexagonal close packed solid is given in terms of existing theories for the mechanisms mentioned above. For the rigid solid regime (up to approximately 14°K), where the relaxation is determined entirely by the first mechanism, this requires that an effective electric quadrupole coupling constant in the solid of from O.SS to 0.62ro be the coupling constant for the isolated pair. In the diffusion dominated regime, 14°K to the triple point all three mechanisms play an important role. Excellent agreement between theory and experiment is obtained for the same r eff, a self-diffusion coefficient Do=9.0SX 10-2 cm 2 /sec and an activation energy Ea =667 cal/mole, except for solids of very low para concentration. For the latter Do= 2.0X 10-2 cm 2 /sec and Ea=608 cal/mole. The theory predicts the observed frequency dependence of the spin-lattice relaxation in the diffusion-dominated regime. In the liquid state a spin-lattice relaxation time can be separately identified for each spin system. Whereas the para-D2 (l = 1, J = 1) results can be accounted for on a model which assumes mechanism (1) modified by the thermal motion in the liquid, no simple explanation is possible for the ortho-D 2 data.
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