The Effects of Acute Tryptophan Depletion on Reactive Aggression in Adults with Attention-Deficit/Hyperactivity Disorder (ADHD) and Healthy Controls

Background: The neurotransmitter serotonin (5-HT) has been linked to the underlying neurobiology of aggressive behavior, particularly with evidence from studies in animals and humans. However, the underlying neurobiology of aggression remains unclear in the context of attention-deficit/hyperactivity disorder (ADHD), a disorder known to be associated with aggression and impulsivity. We investigated the effects of acute tryptophan depletion (ATD), and the resulting diminished central nervous serotonergic neurotransmission, on reactive aggression in healthy controls and adults with ADHD. Methodology/Principal Findings: Twenty male patients with ADHD and twenty healthy male controls were subjected to ATD with an amino acid (AA) beverage that lacked tryptophan (TRP, the physiological precursor of 5-HT) and a TRPbalanced AA beverage (BAL) in a double-blind, within-subject crossover-study over two study days. We assessed reactive aggression 3.25 hours after ATD/BAL intake using a point-subtraction aggression game (PSAG) in which participants played for points against a fictitious opponent. Point subtraction was taken as a measure for reactive aggression. Lowered rates of reactive aggression were found in the ADHD group under ATD after low provocation (LP), with controls showing the opposite effect. In patients with ADHD, trait-impulsivity was negatively correlated with the ATD effect on reactive aggression after LP. Statistical power was limited due to large standard deviations observed in the data on point subtraction, which may limit the use of this particular paradigm in adults with ADHD

Modelling austenite flow curves in low alloy and microalloyed steels

A model has been developed to predict the austenite flow curves of low alloy and microalloyed steels. The model consists basically of two expressions for stress, as a function of strain, temperature, strain rate and the chemical composition of the steel. The first predicts the hardening and dynamic recovery region and the second predicts the softening caused by dynamic recrystallization, the algebraic sum of both expressions predicting the complete flow curve. The model's different parameters are a function of the dimensionless parameter of Sellars and Tegart's equation, which in turn has been modelled not only as a function of temperature and strain rate but also as a function of the chemical composition. In this way one single model may be applied to any hot deformed steel whose composition is the same as or similar to those studied.This work has been undertaken in CENIM (Madrid) and the authors are grateful for the financial support of the DGICYT of Spain (Project PB89-0022). Hernandez’s studies are sponsored by the UNAM (México).Peer reviewe

Modellierung des Transportes von Wasserinhaltsstoffen in Fliessgewaessern unter besonderer Beruecksichtigung des Schwebstoffs

SIGLEAvailable from TIB Hannover: RA 3251(91/E/75) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman