Skyrmions in Quantum Hall Systems with Realistic Force-Laws

We study the charged excitations of quantum Hall systems at integer filling fractions $\nu=2n+1$, for a force-law that takes account of the finite width of the electron gas. For typical values of this width, in the limit of vanishing Zeeman energy we find that the low-energy excitations are ``skyrmions'' not only at $\nu=1$ but also at higher filling fractions. Our results lead to the prediction that, in typical samples, abrupt transitions to charged excitations with very large spins should be observable at filling fractions higher than $\nu=1$ if the Zeeman energy is reduced sufficiently.Comment: 5 pages, 3 ps-figures, revtex with epsf.tex and multicol.sty. To appear in Physical Review

Designing Topological Bands in Reciprocal Space

Motivated by new capabilities to realise artificial gauge fields in ultracold atomic systems, and by their potential to access correlated topological phases in lattice systems, we present a new strategy for designing topologically non-trivial band structures. Our approach is simple and direct: it amounts to considering tight-binding models directly in reciprocal space. These models naturally cause atoms to experience highly uniform magnetic flux density and lead to topological bands with very narrow dispersion, without fine-tuning of parameters. Further, our construction immediately yields instances of optical Chern lattices, as well as band structures of higher Chern number, |C|>1

Relationship qualities that are associated with moments of relational depth: the client's perspective

This study explores the qualities of the therapeutic relationship that are associated with profound moments of interpersonal connectedness. Using a phenomenological approach, qualitative, semi-structured interviews were conducted with 14 participants all of whom had been clients of predominately person-centered counseling. Therapists with whom participants did experience moments of relational depth were experienced as being trustworthy, real, genuinely caring and earnest in their desire to understand. In relationships where they felt there was no moments of relational depth, participants described their therapist as distant, powerful, interpreting, misunderstanding or saying the right words but not really meaning it. Findings are discussed in relation to theory and previous studies, and suggestions for further research given

To bin or not to bin? Deselecting print back-runs available electronically at Imperial College London Library

Accepted versio

Sex differences in the associations between birthweight and lipid levels in middle-age: findings from the 1958 British birth cohort

Objective To examine sex differences in birthweight–lipid associations. Methods and results Using prospectively collected data on birthweight and non-fasting lipid levels at age 44–45 y from the 1958 British birth cohort (3603 men and 3583 women), sex differences in birthweight–lipid associations were examined. There were inverse associations between birthweight and total and low-density-lipoprotein (LDL)-cholesterol among women (a 1 kg increase in birthweight was associated with a 0.13 mmol/L reduction in total cholesterol (p < 0.001) and a 0.07 mmol/L reduction in LDL-cholesterol (p = 0.02)) but no associations among men (p = 0.005 and p = 0.01, respectively, for birthweight × sex interactions). There was an inverse association between birthweight and triglycerides of a similar magnitude in both sexes (a 1 kg increase in birthweight was associated with a 7% reduction in triglyceride levels in sex-adjusted models (p < 0.001)). There was no association between birthweight and high-density-lipoprotein-cholesterol. Associations were largely unaltered after adjustment for covariates. Of birthweight, current height and BMI, the latter was the strongest predictor of lipid levels. Conclusions The finding of an inverse association between birthweight and triglycerides in both sexes and of inverse associations between birthweight and total and LDL-cholesterol only in women suggests that the mechanisms underlying the associations with birthweight may vary for different lipids