Two annual, random samples of clinically suspect cases of bovine spongiform encephalopathy (BSE) were taken in 1992-93 (year 1, 1500 cases) and 1993-94 (year 2, 1000 cases). From each sample, 100 positive cases were examined in detail to establish the severity of the vacuolation in 17 specific neuroanatomical locations. The resultant 'lesion profiles' were compared with the profile obtained from a similar sample of BSE-affected cattle from early in the epidemic (1987-89); the comparison showed that the distribution and severity of vacuolation in BSE has remained unchanged. The cases not confirmed as BSE on histological examination (172 in year 1 and 162 in year 2) were examined for evidence of any alternative neurohistological diagnosis. As in previous studies, the majority of these cases showed no significant lesions (61.6 and 61.7 per cent). The remainder consisted of bilateral focal spongiosis of unknown significance (26.7 and 21.0 per cent), inflammatory conditions (8.1 and 11.1 per cent) and a small number of cases with tumours, cerebrocortical necrosis or idiopathic brainstem neuronal chromatolysis. No evidence was found of any cases of BSE with an atypical distribution of lesions. These findings support the theory that the BSE epidemic is sustained by a single, stable strain of the BSE agent, and confirm that the existing statutory diagnostic criteria continue to be appropriate.
This study examined the effects of neighborhood context on juvenile recidivism to determine if neighborhoods influence the likelihood of reoffending. Although a large body of literature exists regarding the impact of environmental factors on delinquency, very little is known about the effects of these factors on juvenile recidivism. The sample analyzed includes 7,061 delinquent male juveniles committed to community-based programs in Philadelphia, of which 74% are Black, 13% Hispanic, and 11% White. Since sample youths were nested in neighborhoods, a hierarchical generalized linear model was employed to predict recidivism across three general categories of recidivism offenses: drug, violent, and property. Results indicate that predictors vary across the types of offenses and that drug offending differs from property and violent offending. Neighborhood-level factors were found to influence drug offense recidivism, but were not significant predictors of violent offenses, property offenses, or an aggregated recidivism measure, despite contrary expectations. Implications stemming from the finding that neighborhood context influences only juvenile drug recidivism are discussed.
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