Nocturnal activity by the primarily diurnal Central American agouti (Dasyprocta punctata) in relation to environmental conditions, resource abundance and predation risk

An animal's fitness is in part based on its ability to manage the inherent risks (foraging costs, predation, exposure to disease) with the benefits (resource gain, access to mates, social interactions) of activity (Abrams 1991, Altizer et al. 2003, Lima & Bednekoff 1999, Rubenstein & Hohmann 1989, Wikelski et al. 2001). Thus, understanding an animal's pattern of activity is key to understanding behavioural and ecological processes. However, while numerous laboratory methodologies are available to continuously quantify activity over long periods of time, logistical difficulties have greatly hindered activity studies of animals in the field (DeCoursey 1990)

Math-Failure Associations, Attentional Biases, and Avoidance Bias: The Relationship with Math Anxiety and Behaviour in Adolescents

Background: Math anxiety in adolescence negatively affects learning math and careers. The current study investigated whether three cognitive biases, i.e. math-failure associations, attentional biases (engagement and disengagement), and avoidance bias for math, were related to math anxiety and math behaviour (math grade and math avoidance behaviour). Methods: In total, 500 secondary school students performed three cognitive bias tasks, questionnaires and a math performance task, and reported their grades. Results: Math-failure associations showed the most consistent associations with the outcome measures. They were associated with higher math anxiety above and beyond sex and education level. Those math-failure associations were also associated with lower grades and more avoidance behaviour, however, not above and beyond math anxiety. Engagement bias and avoidance tendency bias were associated with math avoidance behaviour, though the avoidance bias finding should be interpreted with care given the low reliability of the measure. Disengagement biases were not associated with any math anxiety nor behaviour outcome measure. Conclusions: Whereas a more reliable instrument for avoidance bias is necessary for conclusions on the relations with math performance and behaviour, the current results do suggest that math-failure associations, and not attentional bias, may play a role in the maintenance of math anxiety.</p

Selective processing of drug cues in heroin dependence

Previous studies provide evidence for the selective processing of disorder related stimuli on anxiety, depression, and eating disorders. There exist some preliminary indications that selective processing of drug cues may be involved in drug craving and relapse that deserve further investigation. In order to investigate the role of processing bias in an abnormal motivational system, the attentional bias for drug related stimuli was studied in a heroin dependent population. Heroin dependent participants (n = 21) and control participants (n = 30) performed a supra- and subliminal heroin Stroop task and heroin craving was assessed. Heroin dependent participants showed a considerable attentional bias for supraliminally presented heroin cues. However, there was no evidence for a preattentive bias on the subliminal presented cues. Reaction time on heroin cues was significantly predicted by heroin craving-levels. Results indicate that selective processing may be related to motivational induced states in general. The finding are discussed in the context of selective information processing in general psychopathology and in motivational processes as addiction specifically

Implicit measures of association in psychopathology research

Studies obtaining implicit measures of associations in Diagnostic and Statistical Manual of Mental Disorders (4th ed., Text Revision; American Psychiatric Association, 2000) Axis I psychopathology are organized into three categories: (a) studies comparing groups having a disorder with controls, (b) experimental validity studies, and (c) incremental and predictive validity studies. In the first category, implicit measures of disorder-relevant associations were consistent with explicit beliefs for some disorders (e.g., specific phobia), but for other disorders evidence was either mixed (e.g., panic disorder) or inconsistent with explicit beliefs (e.g., pain disorder). For substance use disorders and overeating, expected positive and unexpected negative associations with craved substances were found consistently. Contrary to expectation, implicit measures of self-esteem were consistently positive for patients with depressive disorder, social phobia, and body dysmorphic disorder. In the second category, short-term manipulations of disorder-relevant states generally affected implicit measures as expected. Therapeutic interventions affected implicit measures for one type of specific phobia, social phobia, and panic disorder, but not for alcohol use disorders or obesity. In the third category, implicit measures had predictive value for certain psychopathological behaviors, sometimes moderated by the availability of cognitive resources (e.g., for alcohol and food, only when cognitive resources were limited). The strengths of implicit measures include (a) converging evidence for dysfunctional beliefs regarding certain disorders and consistent new insights for other disorders and (b) prediction of some psychopathological behaviors that explicit measures cannot explain. Weaknesses include (a) that findings were inconsistent for some disorders, raising doubts about the validity of the measures, and (b) that understanding of the concept "implicit" is incomplete

Peierls Instabilities in Quasi-One-Dimensional Quantum Double-Well Chains

Peierls-type instabilities in quarter-filled ($\bar{n}=1/2$) and half-filled ($\bar{n}=1$) quantum double-well hydrogen-bonded chain are investigated analytically in the framework of two-stage orientational-tunnelling model with additional inclusion of the interactions of protons with two different optical phonon branches. It is shown that when the energy of proton-phonon coupling becomes large, the system undergoes a transition to a various types of insulator states. The influence of two different transport amplitudes on ground states properties is studied. The results are compared with the pressure effect experimental investigations in superprotonic systems and hydrogen halides at low temperatures.Comment: 7 pages, RevTeX, 9 eps figure