Microbial mediation of benthic biogenic silica dissolution

Pore water profiles from 24 stations in the South Atlantic (located in the Guinea, Angola, Cape, Guyana, and Argentine basins) show good correlations of oxygen and silicon, suggesting microbially mediated dissolution of biogenic silica. We used simple analytical transport and reaction models to show the tight coupling of the reconstructed process kinetics of aerobic respiration and silicon regeneration. A generic transport and reaction model successfully reproduced the majority of Si pore water profiles from aerobic respiration rates, confirming that the dissolution of biogenic silica (BSi) occurs proportionally to O 2 consumption. Possibly limited to well-oxygenated sediments poor in BSi, benthic Si fluxes can be inferred from O 2 uptake with satisfactory accuracy. Compared to aerobic respiration kinetics, the solubility of BSi emerged as a less influential parameter for silicon regeneration. Understanding the role of bacteria for silicon regeneration requires further investigations, some of which are outlined. The proposed aerobic respiration control of benthic silicon cycling is suitable for benthic–pelagic models. The empirical relation of BSi dissolution to aerobic respiration can be used for regionalization assessments and estimates of the silicon budget to increase the understanding of global primary and export production patterns

Evidence-Based Interventions for Violent Behavior in Children and Adolescents

There are very few evidence-based interventions specifically for violent behavior in children and adolescents. However, interventions for antisocial behavior problems have shown some efficacy in violence reduction and are reviewed in detail in this chapter. Effective interventions attempt to target established risk factors and a number of these are outlined, including early onset of antisocial behavior, callous-unemotional traits, poor regulation of anger, family factors and peer influences. The implications of these risk factors for intervention approaches is explored and basic principles of intervention described. The chapter then describes specific interventions, for both children and adolescents, and reviews the evidence on their efficacy. It provides detailed descriptions of some of the most promising interventions using different approaches, in particular those for adolescents, and identifies interventions that have been shown not to work. The chapter concludes with a review of the current evidence base for interventions with children and adolescents with callous-unemotional traits