Reduced products of logical matrices

The class Matr(C) of all matrices for a prepositional logic (, C) is investigated. The paper contains general results with no special reference to particular logics. The main theorem (Th. (5.1)) which gives the algebraic characterization of the class Matr(C) states the following. Assume C to be the consequence operation on a prepositional language induced by a class K of matrices. Let m be a regular cardinal not less than the cardinality of C. Then Matr (C) is the least class of matrices containing K and closed under m-reduced products, submatrices, matrix homomorphisms, and matrix homomorphic counter-images.     

Increasingly cautious sampling,not the black colouration of unpalatable prey,is used by fish in avoidance learning

Animal Cognition - The efficiency of aposematic colouration of prey is based on the innate bias or facilitation of avoidance learning of predators. In many toxic bufonids, larvae are uniformly...     

Prevalence and Correlates of Depressive Symptoms Following Traumatic Brain Injuries in Children

The prevalence and correlates of depressive symptoms following childhood traumatic brain injuries (TBI) were examined using data drawn from a prospective longitudinal study. Participants included 38 children with severe TBI, 51 with moderate TBI, and 55 with orthopedic injuries (OI). Assessments occurred shortly after injury (baseline) and at 6- and 12-month follow-ups. Children completed the Child Depression Inventory (CDI). Parents rated depressive symptoms using the Child Behavior Checklist (CBC), with baseline ratings reflecting premorbid status. Assessments also included measures of children's neurocognitive functioning and the family environment. The three groups did not differ overall in self-reported symptoms on the CDI, but did display different trends over time. The three groups did not differ on parent ratings of premorbid depressive symptoms on the CBC, but parents reported more depressive symptoms in the TBI groups than in the OI group at 6- and 12-month follow-ups. Child and parent reports were correlated for children in the TBI groups, but not for those in the OI group. Depressive symptoms were related to socioeconomic status in all groups. Socioeconomic status also was a significant moderator of group differences, such that the effects of TBI were exacerbated in children from more disadvantaged homes. Although self-reports of depressive symptoms were related inconsistently to children's verbal memory, parent reports of depressive symptoms were unrelated to IQ or verbal memory. The findings suggest that TBI increases the risk of depressive symptoms, especially among more socially disadvantaged children, and that depressive symptoms are not strongly related to post-injury neurocognitive deficits.