Contrasting effects of heat pulses on different trophic levels, an experiment with a herbivore-parasitoid model system

Under predicted global climate change, species will be gradually exposed to warmer temperatures, and to a more variable climate including more intense and more frequent heatwaves. Increased climatic variability is expected to have different effects on species and ecosystems than gradual warming. A key challenge to predict the impact of climate change is to understand how temperature changes will affect species interactions. Herbivorous insects and their natural enemies belong to some of the largest groups of terrestrial animals, and thus they have a great impact on the functioning of ecosystems and on the services these ecosystems provide. Here we studied the life history traits of the plant-feeding insect Plutella xylostella and its specialist endoparasitoid Diadegma semiclausum, when exposed to a daily heat pulse of 5 or 10°C temperature increase during their entire immature phase. Growth and developmental responses differed with the amplitude of the heat pulse and they were different between host and parasitoid, indicating different thermal sensitivity of the two trophic levels. With a +5°C heat pulse, the adult parasitoids were larger which may result in a higher fitness, whereas a +10°C heat pulse retarded parasitoid development. These results show that the parasitoid is more sensitive than its host to brief intervals of temperature change, and this results in either positive or negative effects on life history traits, depending on the amplitude of the heat pulse. These findings suggest that more extreme fluctuations may disrupt host-parasitoid synchrony, whereas moderate fluctuations may improve parasitoid fitness. (Résumé d'auteur

Attentional avoidance of high-fat food in unsuccessful dieters

Using the exogenous cueing task, this study examined whether restrained and disinhibited eaters differ in their orientation of attention towards and their difficulty to disengage from high versus low-fat food pictures in a relatively short (500 ms) and a long presentation format (1500 ms). Overall, participants in the 500 ms condition showed a tendency to direct attention away from high-fat food pictures compared to neutral pictures. No differential pattern was evident for the 1500 ms condition. Correlational analysis revealed that reduced engagement with high-fat food was particularly pronounced for disinhibited eaters. Although in the short term this seems an adaptive strategy, it may eventually become counterproductive, as it could hinder habituation and learning to cope with seductive characteristics of high-fat food. (C) 2010 Elsevier Ltd. All rights reserved

Hidden scars in depression? Implicit and explicit self-associations following recurrent depressive episodes

To help explain the recurrent nature of major depressive disorder, we tested the hypothesis that depressive episodes and/or the duration of depressive symptoms may give rise to persistent dysfunctional implicit and/or more explicit self-associations, which in turn may place people at risk for the recurrence of symptoms. We therefore examined, in the context of the Netherlands Study of Depression and Anxiety, whether the strength of self-depressed associations at baseline was related to the number of past episodes (retrospective analysis; n = 666), and whether the duration of symptoms between baseline and follow-up predicted self-depressed associations at 2-year follow-up (prospective analysis; n = 726). The lifetime Composite International Diagnostic Interviews and Life Chart Interview were used to index the number of depressive episodes; the Implicit Association Test and its explicit equivalent were used to index self-associations. Consistent with the hypothesis that self-depressed associations strengthen following prolonged activation of negative self-associations during depressive episodes, individuals' implicit and explicit self-depressed associations correlated positively both with the number of prior depressive episodes at baseline and with the duration of depressive symptoms between baseline and 2-year follow-up. There was evidence that these relationships held, particularly in the prospective study, even when controlling for neuroticism and current depressive symptoms, whereas the retrospective relationship between number of episodes and implicit self-associations fell just short of significance

Better together?:A randomized controlled microtrial comparing different levels of therapist and parental involvement in exposure-based treatment of childhood specific phobia

INTRODUCTION: Exposure is often limited to homework assignments in routine clinical care. The current study compares minimally-guided (MGE) and parent-guided (PGE) out-session homework formats to the 'golden standard' of therapist-guided in-session exposure with minimally-guided exposure at home (TGE).METHODS: Children with specific phobia (N = 55, age 8-12, 56% girls) participated in a single-blind, randomized controlled microtrial with a four-week baseline-treatment period design. Clinical interviews, behavioral avoidance tests, and self-report measures were assessed at pre-treatment, post-treatment, and at one-month follow-up.RESULTS: TGE resulted in a larger decline of specific phobia severity from baseline to post-treatment compared to MGE but not compared to PGE. Parental anxiety was found to be a moderator of less treatment efficacy of PGE from baseline to post-treatment. Overall, there was no meaningful difference in efficacy of TGE versus MGE or PGE from baseline to follow-up.CONCLUSIONS: These findings suggest that for improving short-term treatment gains, exposure exercises can best be conducted with the help of a therapist within the therapy session before they are conducted as homework assignments outside the therapy session. However, for long-term treatment gains exposure exercises can be handled by the child itself or with help of its parents.</p

Low Satisfaction with Normative Life Domains in Adolescents with Anorexia Nervosa

OBJECTIVE: Low satisfaction with normative life domains might be an important factor in the persistence of anorexia nervosa (AN). Initial evidence in non‐clinical samples showed that lower satisfaction with normative life domains was related to more intense eating disorder symptoms. As a critical next step, the current study examined satisfaction with normative life domains in a clinical sample. Specifically, the present study tested whether adolescents with AN reported lower satisfaction with normative life domains than adolescents without an eating disorder. METHOD: Adolescents with AN (n = 69) and adolescents without an eating disorder matched on age, gender and educational level (n = 69) completed the Brief Multidimensional Students' Life Satisfaction Scale to assess satisfaction with five life domains (family, friendships, school, self and living location) and life in general. RESULTS: Adolescents with AN reported significantly lower satisfaction with normative life domains than the comparison group. Subsequent analyses showed that this overall group difference was primarily driven by adolescents with AN reporting lower satisfaction with the self, school experience and life in general. CONCLUSIONS: Findings supported the hypothesis that adolescents with AN show relatively low satisfaction with meaningful, non‐AN‐related life domains. This points to the potential relevance of enhancing satisfaction with specific life domains to optimize treatment effectiveness

Satisfaction with normative life domains and the course of anorexia nervosa

OBJECTIVE: Satisfaction with normative life domains has been proposed as an important factor in the persistence of anorexia nervosa (AN). Initial evidence from a cross-sectional study indicated that individuals with AN reported lower satisfaction with normative life domains than individuals without an eating disorder. As an important next step in understanding causal relations, the present study used a longitudinal design to examine whether an improvement in AN symptoms is paralleled by an increase in satisfaction with normative life domains from baseline to follow-up and whether relatively low satisfaction with normative life domains at baseline is related to less improvement in AN symptoms. METHODS: During baseline and at 1-year follow-up, adolescents with AN (N = 69) completed the Brief Multidimensional Students' Life Satisfaction Scale to measure satisfaction with normative life domains (e.g., friendships, school experience). Furthermore, eating disorder symptoms and BMI were measured. RESULTS: Improvement in eating disorder symptoms, but not in BMI, was paralleled by an increase in satisfaction with normative life domains. Relatively low satisfaction with normative life domains at baseline was not prospectively related to less improvement in eating disorder symptoms or BMI at follow-up. DISCUSSION: Our findings provide initial evidence that satisfaction with normative life domains is a malleable factor which fluctuates with symptom severity in AN. The results of this exploratory study point to the relevance of examining whether targeting satisfactory engagement with specific life domains optimizes treatment effectiveness. PUBLIC SIGNIFICANCE: We explored whether an improvement in anorexia nervosa symptoms from start of treatment to 1-year follow-up would be paralleled by an increase in satisfaction with normative life domains. Improvement in eating disorder symptoms (but not BMI) was indeed related to a concurrent increase in satisfaction with normative life domains. These preliminary results point to the promising possibility that targeting satisfactory engagement with specific life domains may potentially enhance treatment effectiveness

Star Clusters in the Nearby Late-Type Galaxy NGC 1311

Ultraviolet, optical and near infrared images of the nearby (D ~ 5.5 Mpc) SBm galaxy NGC 1311, obtained with the Hubble Space Telescope, reveal a small population of 13 candidate star clusters. We identify candidate star clusters based on a combination of their luminosity, extent and spectral energy distribution. The masses of the cluster candidates range from ~1000 up to ~100000 Solar masses, and show a strong positive trend of larger mass with increasing with cluster age. Such a trend follows from the fading and dissolution of old, low-mass clusters, and the lack of any young super star clusters of the sort often formed in strong starbursts. The cluster age distribution is consistent with a bursting mode of cluster formation, with active episodes of age ~10 Myr, ~100 Myr and ~1 Gyr. The ranges of age and mass we probe are consistent with those of the star clusters found in quiescent Local Group dwarf galaxies.Comment: 21 pages, 11 figures, accepted by A