Reentrant transition of bosons in a quasiperiodic potential

We investigate the behavior of a two dimensional array of Bose-Einstein condensate tubes described by means of a Bose-Hubbard Hamiltonian. Using a Wannier function expansion for the wavefunction in each tube, we compute the Bose-Hubbard parameters related to two different longitudinal potentials, periodic and quasiperiodic. We predict that - upon increasing the external potential strength along the direction of the tubes - the condensate can experience a reentrant transition between a Mott insulating phase and the superfluid one.Comment: Accepted for publication in EP

On Lundh's percolation difussion

A collection of spherical obstacles in the ball in Euclidean space is said to be avoidable for Brownian motion if there is a positive probability that Brownian motion diffusing from some point in the ball will avoid all the obstacles and reach the boundary of the ball. The centres of the spherical obstacles are generated according to a Poisson point process while the radius of an obstacle is a deterministic function depending only on the distance from the obstacle's centre to the centre of the ball. Lundh has given the name percolation diffusion to this process if avoidable configurations are generated with positive probability. An integral condition for percolation diffusion is derived in terms of the intensity of the Poisson point process and the function that determines the radii of the obstacles

Memory for Emotionally Provocative Words in Alexithymia: A Role for Stimulus Relevance

Alexithymia is associated with emotion processing deficits, particularly for negative emotional information. However, also common are a high prevalence of somatic symptoms and the perception of somatic sensations as distressing. Although little research has yet been conducted on memory in alexithymia, we hypothesized a paradoxical effect of alexithymia on memory. Specifically, recall of negative emotional words was expected to be reduced in alexithymia, while memory for illness words was expected to be enhanced in alexithymia. Eighty-five high or low alexithymia participants viewed and rated arousing illness-related ( pain ), emotionally positive ( thrill ), negative ( hatred ), and neutral words ( horse ). Recall was assessed 45 min later. High alexithymia participants recalled significantly fewer negative emotion words but also more illness-related words than low alexithymia participants. The results suggest that personal relevance can shape cognitive processing of stimuli, even to enhance retention of a subclass of stimuli whose retention is generally impaired in alexithymia

Marriage choices and social reproduction

This article studies the relationship between partner selection and socioeconomic status (SES) attainment and mobility in five rural parishes in southern Sweden, 1815-1894. Three different aspects of partner selection are considered: age, social origin, and geographical origin. We use an individual-level database containing information on the SES origin (parental land holding and occupation), age difference, and place of birth of the married couple. The results show a powerful association between partner selection and SES attainment and mobility. Social heterogamy was particularly important, but age heterogamy and geographic exogamy was also clearly related to both SES attainment and mobility.age homogamy, geographic endogamy, intergenerational social mobility, partner selection, social homogamy, socioeconomic attainment

Front pages with contents of No. 59, 1998

Front cover. Table of Contents

In search of an evolutionary coding style

In the near future, all the human genes will be identified. But understanding the functions coded in the genes is a much harder problem. For example, by using block entropy, one has that the DNA code is closer to a random code then written text, which in turn is less ordered then an ordinary computer code; see \cite{schmitt}. Instead of saying that the DNA is badly written, using our programming standards, we might say that it is written in a different style -- an evolutionary style. We will suggest a way to search for such a style in a quantified manner by using an artificial life program, and by giving a definition of general codes and a definition of style for such codes.Comment: 14 pages, 7 postscript figure

The unidirectional relationship of nightmares on self-harmful thoughts and behaviors

Understanding the direction of the predictive relationship between nightmares and suicidal behaviors is important to model its underlying mechanisms. We examine the direction of this relationship and the mediating role of negative affect. A fixed interval diary study obtained pre-sleep and post-sleep measures of affect, nightmares, and self-harmful thoughts and behaviors (SHTBs) from 72 university students (88.9% female). The results show predictive utility of nightmares on SHTBs - indicating a fourfold increased risk of SHTBs. Additionally, results support the suggestion of a unidirectional predictive influence (of nightmares on likelihood of SHTBs but not vice versa). Moreover, postsleep negative affect partially mediated the relationship between nightmares and postsleep SHTBs. This empirically validates assumptions of directionality for future models