Children with social phobia have lower quality friendships than children with other anxiety disorders

BACKGROUND AND OBJECTIVE

Whilst shy, socially anxious or socially withdrawn children in nonclinical community samples report lower friendship quality (FQ) than nonanxious children, no study has examined the FQ of clinically anxious children. The aim of the study was to examine the FQ of children with anxiety disorders; and whether it differs for clinical children with or without a diagnosis of social phobia (SP).

DESIGN

The study design was cross-sectional self-report.

METHODS

Clinical children - 39 anxiety-disordered children with SP and 28 anxiety-disordered children without SP (No-SP) - presented for psychological treatment, and 29 nonclinical children were recruited from the community. Same-sex close friends were invited to participate using an unrestricted nomination procedure. All children were aged between 7 and 13 years. Both target child and friend completed the Friendship Quality Questionnaire and the Spence Children's Anxiety Scale.

RESULTS

Using multilevel modeling within the framework of the Actor-Partner Interdependence Model, SP dyads were found to report lower overall FQ than No-SP dyads. SP dyads did not report lower overall FQ than nonclinical dyads.

CONCLUSION

Children with SP in their diagnostic profile may be unique in their friendship experiences relative to children with other anxiety disorders.

Serotonin transporter [corrected] methylation and response to cognitive behaviour therapy in children with anxiety disorders

Anxiety disorders that are the most commonly occurring psychiatric disorders in childhood, are associated with a range of social and educational impairments and often continue into adulthood. Cognitive behaviour therapy (CBT) is an effective treatment option for the majority of cases, although up to 35-45% of children do not achieve remission. Recent research suggests that some genetic variants may be associated with a more beneficial response to psychological therapy. Epigenetic mechanisms such as DNA methylation work at the interface between genetic and environmental influences. Furthermore, epigenetic alterations at the serotonin transporter (SERT) promoter region have been associated with environmental influences such as stressful life experiences. In this study, we measured DNA methylation upstream of SERT in 116 children with an anxiety disorder, before and after receiving CBT. Change during treatment in percentage DNA methylation was significantly different in treatment responders vs nonresponders. This effect was driven by one CpG site in particular, at which responders increased in methylation, whereas nonresponders showed a decrease in DNA methylation. This is the first study to demonstrate differences in SERT methylation change in association with response to a purely psychological therapy. These findings confirm that biological changes occur alongside changes in symptomatology following a psychological therapy such as CBT.

An investigation into the lower peer liking of anxious than nonanxious children

Peer dislike of anxious behaviour was investigated in 7-12 year olds. Child actors delivered an identical verbal presentation: once in an anxious manner and once confidently. The videos were rated for liking and seven potential mediators by three groups of children: 32 anxiety-disordered peers with social phobia; 16 anxiety-disordered peers without social phobia; and 48 nonclinical peers. A mediation model with moderation effects was tested within a within-subjects framework. "Anxious" actors were liked significantly less than "confident" actors. This effect differed by group rater, in that relative dislike of the anxious actor was significantly greater for the nonclinical than socially phobic raters. Physical attractiveness and friend acceptance mediated the effect for all group raters. Other identified mediators differed depending upon the group rater. The findings direct future efforts to help anxiety-disordered children circumvent an increased risk of negative peer relations, and testify to consideration of the rater in sociometric studies.

Notizen: Cloud Attractors and Time-Inverted Julia Boundaries

Cloud attractors are predicted to exist in simple invertible systems. The explicit noodle map (a three-dimensional diffeomorphism) and several 4-variable ODEs (describing chemical reactors) provide candidates. A “widely spaced” Lyapunov spectrum (+ , - e, - ) may in general warrant a numerical search.

Spatial Learning Deficits Induced by Muscimol and CL218,872: Lack of Effect of Prenatal Malnutrition

The sensitivity of prenatal protein malnourished rats to the amnestic properties of the direct GABAA receptor agonist muscimol and the selective benzodiazepine (BZ) receptor agonist, CL218,872, was studied in the male offspring of rats provided with a protein deficient diet (6% casein) for 5 weeks prior to mating and throughout pregnancy. At postnatal day 90, rats were tested during acquisition of the submerged platform version of the Morris water maze task using four systemic doses of muscimol (0.1, 0.3, 1.0 and 1.8 mg/kg i.p.) or three systemic doses of CL218,872 (1.0, 3.2, and 5.6 mg/kg i.p.). In a dose dependent manner both drugs impaired acquisition of the task and impaired accuracy of the search pattern on the probe trial (platform removed). However, neither drug dissociated the performance of the two nutritional groups. These data are important in light of previous findings of differential behavioral effects of the non-specific BZ agonist, chlordiazepoxide (CDP), on spatial learning and on drug discrimination in prenatally malnourished rats and in the context of previous findings of reduced sensitivity to the anxiolytic effects of non-specific BZ receptor agonists across a wide variety of models of malnutrition. The present findings also support the concept that prenatal malnutrition does not affect the global functioning of the GABAA receptor, but fundamentally alters the way in which a subset of GABAA receptors (i.e. those containing the alpha2, alpha3 and/or the alpha5 but not the alpha1 subunit) is modulated by BZs.

An automated algorithm for the generation of dynamically reconstructed trajectories

The lack of long enough data sets is a major problem in the study of many real world systems. As it has been recently shown [C. Komalapriya, M. Thiel, M. C. Romano, N. Marwan, U. Schwarz, and J. Kurths, Phys. Rev. E 78, 066217 (2008)], this problem can be overcome in the case of ergodic systems if an ensemble of short trajectories is available, from which dynamically reconstructed trajectories can be generated. However, this method has some disadvantages which hinder its applicability, such as the need for estimation of optimal parameters. Here, we propose a substantially improved algorithm that overcomes the problems encountered by the former one, allowing its automatic application. Furthermore, we show that the new algorithm not only reproduces the short term but also the long term dynamics of the system under study, in contrast to the former algorithm. To exemplify the potential of the new algorithm, we apply it to experimental data from electrochemical oscillators and also to analyze the well-known problem of transient chaotic trajectories.

Sudden Onset of Pitting Corrosion on Stainless Steel as a Critical Phenomenon

Stainless steels undergo a sharp rise in pitting corrosion rate as the potential, solution concentration, or temperature is changed only slightly. We report experiments using real-time microscopic in situ visualizations that resolve the nucleation and evolution of individual pits during the transition. They suggest that the sudden onset of corrosion is explained by an explosive autocatalytic growth in the number of metastable pits and that stabilization of individual pits takes place only later. This finding agrees with a theoretical approach treating the onset of pitting corrosion as a cooperative critical phenomenon resulting from interactions among metastable pits, and it extends perspectives on the control and prevention of corrosion onset.

Adaptive control of unknown unstable steady states of dynamical systems

A simple adaptive controller based on a low-pass filter to stabilize unstable steady states of dynamical systems is considered. The controller is reference-free; it does not require knowledge of the location of the fixed point in the phase space. A topological limitation similar to that of the delayed feedback controller is discussed. We show that the saddle-type steady states cannot be stabilized by using the conventional low-pass filter. The limitation can be overcome by using an unstable low-pass filter. The use of the controller is demonstrated for several physical models, including the pendulum driven by a constant torque, the Lorenz system, and an electrochemical oscillator. Linear and nonlinear analyses of the models are performed and the problem of the basins of attraction of the stabilized steady states is discussed. The robustness of the controller is demonstrated in experiments and numerical simulations with an electrochemical oscillator, the dissolution of nickel in sulfuric acid; a comparison of the effect of using direct and indirect variables in the control is made. With the use of the controller, all unstable phase-space objects are successfully reconstructed experimentally.

Cooperative action of coherent groups in broadly heterogeneous populations of interacting chemical oscillators

We present laboratory experiments on the effects of global coupling in a population of electrochemical oscillators with a multimodal frequency distribution. The experiments show that complex collective signals are generated by this system through spontaneous emergence and joint operation of coherently acting groups representing hierarchically organized resonant clusters. Numerical simulations support these experimental findings. Our results suggest that some forms of internal self-organization, characteristic for complex multiagent systems, are already possible in simple chemical systems.

Stabilizing and tracking unknown steady States of dynamical systems

An adaptive dynamic state feedback controller for stabilizing and tracking unknown steady states of dynamical systems is proposed. We prove that the steady state can never be stabilized if the system and controller in sum have an odd number of real positive eigenvalues. For two-dimensional systems, this topological limitation states that only an unstable focus or node can be stabilized with a stable controller, and stabilization of a saddle requires the presence of an unstable degree of freedom in a feedback loop. The use of the controller to stabilize and track saddle points (as well as unstable foci) is demonstrated both numerically and experimentally with an electrochemical Ni dissolution system.

Suppressing spatiotemporal disorder via local perturbations in an electrochemical cell

We report experimental results depicting suppression of complex spatiotemporal dynamics under the influence of local periodic stimulations. In an experimental electrochemical system, applying a continuous forcing signal to one of the sites in an array of eight coupled oscillators, the naturally complex behavior of the remaining seven electrodes can be converted to periodic responses. The oscillations remain periodic as long as the forcing is active and revert back to exhibiting chaotic dynamics after the control is switched off. These results can also be interpreted as experimental realization of "phase-synchronization" induced via local driving in an extended system. A possible relevance to the experimentally observed calcium wave patterns is pointed out.

Parent-child interactions and anxiety disorders: an observational study

Past research has indicated a potential link between anxiety and parenting styles that are characterised by control and rejection. However, few studies have utilised observational methods to support these findings. In the current study, mother-child interactions were observed while the child completed two difficult cognitive tasks. The sample consisted of clinically anxious children (n=43), oppositional defiant children (n=20) and non-clinical children (n=32). After adjusting for the age and sex of the child, mothers of anxious children and mothers of oppositional children displayed greater and more intrusive involvement than mothers of non-clinical children. Mothers of anxious children were also more negative during the interactions than mothers of non-clinical children. The differences between anxious and non-clinical interactions were equivalent across three separate age groups. The results support the relationship between an overinvolved parenting style and anxiety but question the specificity of this relationship.

Phase synchronization and suppression of chaos through intermittency in forcing of an electrochemical oscillator

External periodic forcing was applied to a chaotic chemical oscillator in experiments on the electrodissolution of Ni in sulfuric acid solution. The amplitude and the frequency (Omega) of the forcing signal were varied in a region around Omega=omega(0), where omega(0) is the frequency of the unforced signal. Phase synchronization occurred with increase in the amplitude of the forcing. For Omega/omega(0) near 1 the signal remained chaotic after the transition to the phase-locked state; for Omega/omega(0) somewhat farther from 1 the transition was to a periodic state via intermittency. The experimental results are supported by numerical simulations using a general model for electrochemical oscillations.