Post-eruptive mobility of lithium in volcanic rocks.

To reflect magmatic conditions, volcanic rocks must retain their compositions through eruption and post-eruptive cooling. Mostly, this is the case. However, welded ignimbrites from the Yellowstone-Snake River Plain magmatic province reveal systematic modification of the lithium (Li) inventory by post-eruptive processes. Here we show that phenocrysts from slowly cooled microcrystalline ignimbrite interiors consistently have significantly more Li than their rapidly quenched, glassy, counterparts. The strong association with host lithology and the invariance of other trace elements indicate that Li remains mobile long after eruption and readily passes into phenocrysts via diffusion as groundmass crystallisation increases the Li contents of the last remaining melts. Li isotopic measurements reveal that this diffusion during cooling combined with efficient degassing on the surface may significantly affect the Li inventory and isotopic compositions of volcanic rocks. Utilisation of Li for petrogenetic studies is therefore crucially dependent on the ability to 'see through' such post-eruptive processes.

MMPI profile subtypes of incarcerated sex offenders against children.

Sex offenders are heterogeneous in personality and behavioral characteristics. The present study was conducted to identify homogeneous subgroups of incarcerated sexual offenders against children on the basis of the Minnesota Multiphasic Personality Inventory (MMPI). Subjects were 90 men undergoing initial evaluation for a treatment program conducted through a state department of corrections. Hierarchical cluster analysis resulted in the identification of four profile subgroups. While two subgroups presented mean profiles within normal limits, the patterns indicated differences in personality functioning: one presenting signs of sociopathy and the other emotional disturbance. In contrast, the other two profile subgroups presented several scale elevations: One subgroup indicated anger and aggression and the other severe psychopathology. Both of the latter subgroups were similar to two rapist subtypes identified in previous research. Subgroups were further differentiated on the basis of psychosexual, affective, and psychosocial variables. Results suggest the existence of homogeneous subgroups of incarcerated sexual offenders against children as delineated by the MPPI.

Cluster analytically derived MMPI profile subgroups of incarcerated adult rapists.

Sex offenders are known to be heterogeneous in their patterns of personality functioning and behavior. The present study conducted a multivariate cluster analysis on the MMPIs of 120 incarcerated adult male rapists. The analysis resulted in the identification of five MMPI profile subgroups. Additional differences among subgroups were identified in the circumstances of the crime and responses to the Multiphasic Sex Inventory. Levels of psychopathology, as indicated by the MMPI, ranged from slight to extreme. Results are discussed with reference to previous MMPI research with sex offenders. Suggestions for future research are offered.