Energy barriers in spin glasses

For an Ising spin glass on a hierarchical lattice, we show that the energy barrier to be overcome during the flip of a domain of size L scales as L to the power d-1 for all dimensions d. We do this by investigating appropriate lower bounds to the barrier energy, which can be evaluated using an algorithm that remains fast for large system sizes and dimensions. The asymptotic limit of infinite dimensions is evaluated analytically.Comment: 4 pages, 5 figure

Learning Features that Predict Cue Usage

Our goal is to identify the features that predict the occurrence and placement of discourse cues in tutorial explanations in order to aid in the automatic generation of explanations. Previous attempts to devise rules for text generation were based on intuition or small numbers of constructed examples. We apply a machine learning program, C4.5, to induce decision trees for cue occurrence and placement from a corpus of data coded for a variety of features previously thought to affect cue usage. Our experiments enable us to identify the features with most predictive power, and show that machine learning can be used to induce decision trees useful for text generation.Comment: 10 pages, 2 Postscript figures, uses aclap.sty, psfig.te

Chronological Catalog of Reported Lunar Events

Chronological catalog of reported lunar events or temperature changes on moon recorded between 1540 and 1967

The Link Overlap and Finite Size Effects for the 3D Ising Spin Glass

We study the link overlap between two replicas of an Ising spin glass in three dimensions using the Migdal-Kadanoff approximation and scaling arguments based on the droplet picture. For moderate system sizes, the distribution of the link overlap shows the asymmetric shape and large sample-to-sample variations found in Monte Carlo simulations and usually attributed to replica symmetry breaking. However, the scaling of the width of the distribution, and the link overlap in the presence of a weak coupling between the two replicas are in agreement with the droplet picture. We also discuss why it is impossible to see the asymptotic droplet-like behaviour for moderate system sizes and temperatures not too far below the critical temperature.Comment: 7 pages, 10 figure

Factors Associated with Underachievement in Eighth-Grade Children

This study investigated characteristics of underachieving adolescents. The Iowa Tests of Basic Skills (ITBS; Hieronymous, et al., 1990) and grade point averages provided the basis for selection of 83 eighth grade students into achiever and underachiever groups. Results indicated that underachievement was significantly related to males, number of absences, and number of discipline referrals, but not to race and notice of special education records. Overall self-esteem, as measured by the Self-Esteem Index (SEI; Brown & Alexander, 1991), and the subscale measure of perceptions of weak academic competence were positively related to level of underachievement/overachievement. Composite measure of behavioral/emotional problems, as measured by the Youth Self-Report (YSR; Achenbach, 1991) and the subscale measure of thought problems were positively related to levels of underachievement/overachievement