Dust formation in astrophysical environments: the importance of kinetics

Laboratory astrophysics and astrochemistr

Stability of polycyclic aromatic hydrocarbon clusters in protoplanetary discs

Interstellar matter and star formatio

Mid-infrared spectroscopic signatures of dibenzopyrene cations: the effect of symmetry on PAH IR spectroscopy

Interstellar matter and star formatio

Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H_2 formation

Interstellar matter and star formationLaboratory astrophysics and astrochemistr

Mechanisms of attention for cues associated with rewarding and aversive outcomes

Attentional biases arising from classical conditioning processes may contribute to the maintenance of drug addictions and anxiety disorders. This thesis examined whether attentional mechanisms for conditioned stimuli (CS) would be dominated by affective properties (Lang, Greenwald, Bradley, & Hamm, 1993), or the uncertainty of the stimulus in predicting the outcome (Pearce & Hall, 1980). In chapter one affective and uncertainty-driven mechanisms of attention are discussed in relation to rewarding and aversive outcomes. In experimental chapter 2 methodological issues are addressed. In experimental chapters three and four attentional mechanisms are tested using a discriminative conditioning procedure with visual stimuli of varying predictive certainty (CS+,CS+/-,CS-) for a monetary or noise outcome (US). Attention was measured using an eye-tracker, and emotional conditioning and learning were measured using Likert scales. It was found that attention was mediated by uncertainty (chapter 3), but increasing the intensity of the outcome switched attention to affective-driven mechanisms for the noise outcome (chapter 4). In a further experiment this effect on attention remained for the noise outcome even under conditions promoting uncertainty-driven mechanisms (chapter 6). When cigarettes were the unconditioned stimuli instead of money in the appetitive conditioning, attention was also mediated by stimulus affect (chapter 5). In chapter 7 the data are discussed and it is concluded that when the outcome is highly emotionally salient, affective-driven mechanisms of attention dominate over uncertainty

Polycyclic Aromatic Hydrocarbon emission model in photodissociation regions - I.: Application to the 3.3, 6.2, and 11.2 μm bands

Laboratory astrophysics and astrochemistryInterstellar matter and star formatio