From Few to Many: Observing the Formation of a Fermi Sea One Atom at a Time

Knowing when a physical system has reached sufficient size for its macroscopic properties to be well described by many-body theory is difficult. We investigate the crossover from few to many-body physics by studying quasi one-dimensional systems of ultracold atoms consisting of a single impurity interacting with an increasing number of identical fermions. We measure the interaction energy of such a system as a function of the number of majority atoms for different strengths of the interparticle interaction. As we increase the number of majority atoms one by one we observe the fast convergence of the normalized interaction energy towards a many-body limit calculated for a single impurity immersed in a Fermi sea of majority particles.Comment: 9 pages, 5 figure

Linking shyness to social anxiety in children through the Clark and Wells cognitive model

This is the author accepted manuscript. The final version is available from Ellinika Grammata via the link in this record.Past research has begun to show that cognitive biases partially mediate the relation between shyness and social anxiety. In addition, it has been showed that the Clark and Wells (1995) cognitive model generalizes to youth. This study investigated the mediating role of the model in the link between shyness and social anxiety. Participants were 306 preadolescents, who completed measures of shyness, social anxiety, and cognitive variables implicated by the model (anticipatory processing, post-event processing, and social attitudes). The results confirmed that shyness, social anxiety and maladaptive cognitive processes were intercorrelated. Further, in a multiple mediator model, social attitudes, but not anticipatory or post-event processing, partially mediated the relation between shyness and social anxiety. Implications for school prevention interventions are briefly discussed

Scattering off an oscillating target: Basic mechanisms and their impact on cross sections

We investigate classical scattering off a harmonically oscillating target in two spatial dimensions. The shape of the scatterer is assumed to have a boundary which is locally convex at any point and does not support the presence of any periodic orbits in the corresponding dynamics. As a simple example we consider the scattering of a beam of non-interacting particles off a circular hard scatterer. The performed analysis is focused on experimentally accessible quantities, characterizing the system, like the differential cross sections in the outgoing angle and velocity. Despite the absence of periodic orbits and their manifolds in the dynamics, we show that the cross sections acquire rich and multiple structure when the velocity of the particles in the beam becomes of the same order of magnitude as the maximum velocity of the oscillating target. The underlying dynamical pattern is uniquely determined by the phase of the first collision between the beam particles and the scatterer and possesses a universal profile, dictated by the manifolds of the parabolic orbits, which can be understood both qualitatively as well as quantitatively in terms of scattering off a hard wall. We discuss also the inverse problem concerning the possibility to extract properties of the oscillating target from the differential cross sections.Comment: 18 page

Bose-Hubbard model with occupation dependent parameters

We study the ground-state properties of ultracold bosons in an optical lattice in the regime of strong interactions. The system is described by a non-standard Bose-Hubbard model with both occupation-dependent tunneling and on-site interaction. We find that for sufficiently strong coupling the system features a phase-transition from a Mott insulator with one particle per site to a superfluid of spatially extended particle pairs living on top of the Mott background -- instead of the usual transition to a superfluid of single particles/holes. Increasing the interaction further, a superfluid of particle pairs localized on a single site (rather than being extended) on top of the Mott background appears. This happens at the same interaction strength where the Mott-insulator phase with 2 particles per site is destroyed completely by particle-hole fluctuations for arbitrarily small tunneling. In another regime, characterized by weak interaction, but high occupation numbers, we observe a dynamical instability in the superfluid excitation spectrum. The new ground state is a superfluid, forming a 2D slab, localized along one spatial direction that is spontaneously chosen.Comment: 16 pages, 4 figure

The predictors of anticipatory processing before a social-evaluative situation

This is the author accepted manuscript. The final version is available from Textrum via the DOI in this record.Anticipatory processing is a repetitive thinking process that precedes social-evaluative events. The aim of this study was to examine factors that may predict the extent to which individuals engage in anticipatory processing. Perfectionistic beliefs, social interaction anxiety, anxiety sensitivity, anticipatory processing, and positive beliefs about anticipatory processing were assessed in a large college student sample (N = 225). Anticipatory processing was greater prior to performance situations relative to social interaction situations. In addition, social interaction anxiety, positive beliefs about anticipatory processing and anxiety sensitivity, but not perfectionistic beliefs, significantly predicted the extent to which the participants engaged in anticipatory processing related to an anxiety-provoking event. Finally, factors that appear to impact on the anticipatory processing varied according to the nature of social situation

Mind What Teachers Say: Kindergarten Teachers' Use of Mental State Language During Picture Story Narration

The study focuses on the mental state language kindergarten teachers use when narrating picture stories. The aims were to examine (a) individual differences in the frequency with which kindergarten teachers use mental state terms, (b) the types of mental state terms (e.g., emotion, desire, belief terms) teachers use most frequently, and (c) the effect that the content of the story to be narrated has on teachers' use of mental state language. A total of 38 kindergarten teachers took part in the study. Participants were asked to narrate a familiar picture story and six short illustrated stories that fell into one of two categories: behavioral or mentalistic. Behavioral stories emphasized the story characters' actions, whereas mentalistic stories emphasized the story characters' mental states. Research Findings: The results showed a significant variation in kindergarten teachers' use of mental state terms. Moreover, teachers used significantly more cognitive state terms than terms expressing other mental states (e.g., emotions and desires). The content of the picture story (behavioral, mentalistic) was not found to have an effect on teachers' use of mental state language. Practice or Policy: Implications of these findings for educators are discussed. © 2013 Copyright Taylor and Francis Group, LLC

A Multi-Session Attribution Modification Program for Children with Aggressive Behaviour: Changes in Attributions, Emotional Reaction Estimates, and Self-Reported Aggression

Background: Research suggests that aggressive children are prone to over-attribute hostile intentions to peers. Aims: The current study investigated whether this attributional style can be altered using a Cognitive Bias Modification of Interpretations (CBM-I) procedure. Method: A sample of 10-12-year-olds selected for displaying aggressive behaviours was trained over three sessions to endorse benign rather than hostile attributions in response to ambiguous social scenarios. Results: Compared to a test-retest control group (n = 18), children receiving CBM-I (n = 16) were less likely to endorse hostile attributions and more likely to endorse benign attributions in response to a new set of ambiguous social situations. Furthermore, aggressive behaviour scores reduced more in the trained group than in the untrained controls. Children who received attribution training also reported less perceived anger and showed a trend to report more self-control than those in the control group. Conclusions: Implications of these findings are discussed

The relationships between metacognition, anticipatory processing, and social anxiety

PublishedArticleAnticipatory processing (AP) is a repetitive thinking style associated with social anxiety that has been understudied relative to other similar constructs (e.g., rumination, worry). The primary goal of this study was the development and evaluation of the Positive Beliefs about Anticipatory Processing Questionnaire (PB-APQ) with a sample of 301 undergraduate students. Further, it was predicted that anticipatory processing would mediate the relationship between positive beliefs about anticipatory processing and social interaction anxiety. The findings from this study suggest that PB-APQ is a valid and reliable construct. Anticipatory processing was shown to partially mediate the relationship between positive beliefs about anticipatory processing and social interaction anxiety. The results provide initial evidence for the suggestion that individuals who tend to hold positive beliefs about anticipatory processing tend to engage in anticipatory processing, which may increase social interaction anxiety

A problem-oriented group approach to reduce children’s fears and concerns about the secondary school transition

This is the author accepted manuscript. The final version is available from CUP via the DOI in this recordTo facilitate students’ transition into secondary school, a short, problem-oriented group program was designed that included interpretation retraining, problem solving, and social-skills training. Pre- and post-test data from two groups conducted over the course of 5 weeks were combined for a total of 35 6th-grade students waiting to undergo school transition. There was also a no-intervention control group (n = 19). Results indicate that completion of the program by the intervention group led to a significant decrease on negative interpretations, with greater reductions in feelings of loneliness and increases in children's positive attitudes toward school compared to the control group. In addition, 3 months before moving to secondary school, children in the intervention group reported significantly fewer concerns about school transition compared with the controls. We conclude that the inclusion of problem-based strategies may be beneficial when designing transition groups, which may also lead to a significant reduction in worries and concerns about the transition to secondary school