The Quantum Hall Effect in Drag: Inter-layer Friction in Strong Magnetic Fields

We study the Coulomb drag between two spatially separated electron systems in a strong magnetic field, one of which exhibits the quantum Hall effect. At a fixed temperature, the drag mimics the behavior of $\sigma_{xx}$ in the quantum Hall system, in that it is sharply peaked near the transitions between neighboring plateaux. We assess the impact of critical fluctuations near the transitions, and find that the low temperature behavior of the drag measures an exponent $\eta$ that characterizes anomalous low frequency dissipation; the latter is believed to be present following the work of Chalker.Comment: 13 pages, Revtex 2.0, 1 figure upon request, P-93-11-09

Frictional Coulomb drag in strong magnetic fields

A treatment of frictional Coulomb drag between two 2-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity $\rho_{21}$ is evaluated using diagrammatic techniques. The transresistivity is given by an integral over energy and momentum transfer weighted by the product of the screened interlayer interaction and the phase-space for scattering events. We demonstrate, by a numerical analysis of the transresistivity, that for well-resolved Landau levels the interplay between these two factors leads to characteristic features in both the magnetic field- and the temperature dependence of $\rho_{21}$. Numerical results are compared with recent experiments.Comment: RevTeX, 34 pages, 8 figures included in tex

Correlations, compressibility, and capacitance in double-quantum-well systems in the quantum Hall regime

In the quantum Hall regime, electronic correlations in double-layer two-dimensional electron systems are strong because the kinetic energy is quenched by Landau quantization. In this article we point out that these correlations are reflected in the way the partitioning of charge between the two-layers responds to a bias potential. We report on illustrative calculations based on an unrestricted Hartree-Fock approximation which allows for spontaneous inter-layer phase coherence. The possibility of studying inter-layer correlations by capacitive coupling to separately contacted two-dimensional layers is discussed in detail.Comment: RevTex style, 21 pages, 6 postscript figures in a separate file; Phys. Rev. B (in press

Maintenance treatment with quetiapine versus discontinuation after one year of treatment in patients with remitted first episode psychosis: randomised controlled trial

Objective To study rates of relapse in remitted patients with first episode psychosis who either continued or discontinued antipsychotic drugs after at least one year of maintenance treatment

Charged Many-Electron -- Single Hole Complexes in a Double Quantum Well near a Metal Plate

It has been shown that the presence of a metal plate near a double quantum well with spatially separated electron and hole layers may lead to a drastic reconstruction of the system state with the formation of stable charged complexes of several electrons bound to a spatially separated hole. Complexes of both the Fermi and the Bose statistics may coexist in the ground state and their relative densities may be changed with the change of the electron and hole densities. The stability of the charged complexes may be increased by an external magnetic field perpendicular to the layers plane.Comment: to appear in Phys.Rev.Lett. 77, No.7 (1996). 4 pages, RevTeX, 1 figur

Evaluation of the combined use of adiponectin and C-reactive protein levels as biomarkers for predicting the deterioration in glycaemia after a median of 5.4 years

Aims/hypothesis: Hypoadiponectinaemia and raised C-reactive protein (CRP) level are obesity-related biomarkers associated with glucose dysregulation. We evaluated the combined use of these two biomarkers in predicting the deterioration of glycaemia in a prospective study after a median of 5.4 years. Methods: In total 1,288 non-diabetic participants from the Hong Kong Cardiovascular Risk Factor Prevalence Study-2, with high-sensitivity CRP (hsCRP) and total adiponectin levels measured were included. OGTT was performed in all participants. Two hundred and six participants had deterioration of glycaemia at follow-up, whereas 1,082 participants did not. Results: Baseline age, hsCRP and adiponectin levels were significant independent predictors of the deterioration of glycaemia in a Cox regression analysis after adjusting for baseline age, sex, BMI, hypertension, triacylglycerols, 2 h post-OGTT glucose and homeostasis model assessment of insulin resistance index (all p < 0.01). The introduction of hsCRP or adiponectin level to a regression model including the other biomarker improved the prediction of glycaemic progression significantly in all participants, especially in women (all p < 0.01). The combined inclusion of the two biomarkers resulted in a modest improvement in model discrimination, compared with the inclusion of either one alone. Among participants with impaired fasting glucose/impaired glucose tolerance (IFG/IGT) at baseline, hsCRP and adiponectin levels were not predictive of progression or improvement of glycaemic status. Conclusions/interpretation: Adiponectin and hsCRP levels are independent factors in predicting the deterioration of glycaemia, supporting the role of adiposity-related inflammation in the development of type 2 diabetes. Their combined use as predictive biomarkers is especially useful in women, but not in participants with IFG/IGT. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

A statistical interpretation of the correlation between intermediate mass fragment multiplicity and transverse energy

Multifragment emission following Xe+Au collisions at 30, 40, 50 and 60 AMeV has been studied with multidetector systems covering nearly 4-pi in solid angle. The correlations of both the intermediate mass fragment and light charged particle multiplicities with the transverse energy are explored. A comparison is made with results from a similar system, Xe+Bi at 28 AMeV. The experimental trends are compared to statistical model predictions.Comment: 7 pages, submitted to Phys. Rev.

Combined Use of Serum Adiponectin and Tumor Necrosis Factor-Alpha Receptor 2 Levels Was Comparable to 2-Hour Post-Load Glucose in Diabetes Prediction

Background: Adipose tissue inflammation and dysregulated adipokine secretion are implicated in obesity-related insulin resistance and type 2 diabetes. We evaluated the use of serum adiponectin, an anti-inflammatory adipokine, and several proinflammatory adipokines, as biomarkers of diabetes risk and whether they add to traditional risk factors in diabetes prediction. Methods: We studied 1300 non-diabetic subjects from the prospective Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS). Serum adiponectin, tumor necrosis factor-alpha receptor 2 (TNF-α R2), interleukin-6 (IL-6), adipocyte-fatty acid binding protein (A-FABP) and high-sensitivity C-reactive protein (hsCRP) were measured in baseline samples. Results: Seventy-six participants developed diabetes over 5.3 years (median). All five biomarkers significantly improved the log-likelihood of diabetes in a clinical diabetes prediction (CDP) model including age, sex, family history of diabetes, smoking, physical activity, hypertension, waist circumference, fasting glucose and dyslipidaemia. In ROC curve analysis, "adiponectin + TNF-α R2" improved the area under ROC curve (AUC) of the CDP model from 0.802 to 0.830 (P = 0.03), rendering its performance comparable to the "CDP + 2-hour post-OGTT glucose" model (AUC = 0.852, P = 0.30). A biomarker risk score, derived from the number of biomarkers predictive of diabetes (low adiponectin, high TNF-α R2), had similar performance when added to the CDP model (AUC = 0.829 [95% CI: 0.808-0.849]). Conclusions: The combined use of serum adiponectin and TNF-α R2 as biomarkers provided added value over traditional risk factors for diabetes prediction in Chinese and could be considered as an alternative to the OGTT. © 2012 Woo et al.published_or_final_versio