Teaching statistics using dance and movement

Opinion piece regarding the Dancing Statistics project, focusing on rationale for, and response to the films

Hepatic 18F-FDG Uptake Measurements on PET/MR: Impact of Volume of Interest Location on Repeatability

Background. To investigate same day 18F-FDG (Fluorodeoxyglucose) PET (Positron Emission Tomography)/MR (Magnetic Resonance) test-retest repeatability of Standardized Uptake Value measurements normalized for body weight (SUV) and lean body mass (SUL) in different locations in the liver. Methods. This prospective study was IRB approved with written informed consent obtained. 35 patients (20 women and 15 men, 61±11.2 years) that performed a whole-body 18F-FDG PET/MR followed by liver-dedicated contrast-enhanced 18F-FDG PET/MR were included. SUV/L max, mean, and peak were measured inferior to, superior to, and at the right portal vein and in the left lobe of the liver. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated and Bland-Altman plots were obtained. Results. The variability for SUV/L’s measurements was lowest inferior to the portal vein (<9.2%) followed by measurements performed at the level of the portal vein (<14.6%). Conclusion. The area inferior to the portal vein is the most reliable location for hepatic 18F-FDG uptake measurements on PET/MR

Broken-Symmetry States in Quantum Hall Superlattices

We argue that broken-symmetry states with either spatially diagonal or spatially off-diagonal order are likely in the quantum Hall regime, for clean multiple quantum well (MQW) systems with small layer separations. We find that for MQW systems, unlike bilayers, charge order tends to be favored over spontaneous interlayer coherence. We estimate the size of the interlayer tunneling amplitude needed to stabilize superlattice Bloch minibands by comparing the variational energies of interlayer-coherent superlattice miniband states with those of states with charge order and states with no broken symmetries. We predict that when coherent miniband ground states are stable, strong interlayer electronic correlations will strongly enhance the growth-direction tunneling conductance and promote the possibility of Bloch oscillations.Comment: 9 pages LaTeX, 4 figures EPS, to be published in PR

Bias-voltage induced phase-transition in bilayer quantum Hall ferromagnets

We consider bilayer quantum Hall systems at total filling factor $\nu=1$ in presence of a bias voltage $\Delta_v$ which leads to different filling factors in each layer. We use auxiliary field functional integral approach to study mean-field solutions and collective excitations around them. We find that at large layer separation, the collective excitations soften at a finite wave vector leading to the collapse of quasiparticle gap. Our calculations predict that as the bias voltage is increased, bilayer systems undergo a phase transition from a compressible state to a $\nu=1$ phase-coherent state {\it with charge imbalance}. We present simple analytical expressions for bias-dependent renormalized charge imbalance and pseudospin stiffness which are sensitive to the softening of collective modes.Comment: 12 pages, 5 figures. Minor changes, one reference adde

Solitons in polarized double layer quantum Hall systems

A new manifestation of interlayer coherence in strongly polarized double layer quantum Hall systems with total filling factor $\nu=1$ in the presence of a small or zero tunneling is theoretically predicted. It is shown that moving (for small tunneling) and spatially localized (for zero tunneling) stable pseudospin solitons develop which could be interpreted as mobile or static charge-density excitations. The possibility of their experimental observation is also discussed.Comment: Phys. Rev. B (accepted

Global phase diagram of bilayer quantum Hall ferromagnets

We present a microscopic study of the interlayer spacing d versus in-plane magnetic field $B_\parallel$ phase diagram for bilayer quantum Hall (QH) pseudo-ferromagnets. In addition to the interlayer charge balanced commensurate and incommensurate states analyzed previously, we address the corresponding interlayer charge unbalanced "canted" QH states. We predict a large anomaly in the bilayer capacitance at the canting transition and the formation of dipole stripe domains with periods exceeding 1 micron in the canted state.Comment: 4 RevTeX pgs, 2 eps figures, submitted to PR

On emotions and salsa : some thoughts on dancing to rethink consumers

Dance forms are a big business, highly marketable commoditized cultural universes, with a plethora of markets constructed around their spirit, vitality and possibilities. In this paper, we explore one particular dance form, that of Salsa, arguing that as consumer researchers we look for a more vibrant vocabulary and mindset with which to capture the experiential and transcendental nature of such social associations. We demonstrate that the metaphor of dancing is useful to revitalize our notions of consumer actions; taking them out of the grey mundane of calculative and rational action into the possibilities of emotional economies constructed around the effervescence and vitality of the social (cf. Maffesoli, [1996])

Composite Fermions and the Fermion-Chern-Simons Theory

The concept of composite fermions, and the related Fermion-Chern-Simons theory, have been powerful tools for understanding quantum Hall systems with a partially full lowest Landau level. We shall review some of the successes of the Fermion-Chern-Simons theory, as well as some limitations and outstanding issues.Comment: 13 pages, including 2 figures. Invited talk at International Symposium, Quantum Hall Effect: Past, Present and Future, Stuttgart, July 2003. Proceedings to appear in Physica

Pseudo-spin canting transition in bilayer quantum Hall ferromagnets: a self-charging capacitor

For sufficiently strong in-plane magnetic field a $\nu_T=1$ bilayer quantum Hall pseudo-ferromagnet is expected to exhibit a soliton lattice. For sufficiently close layers and large in-plane field, we predict this incommensurate ``planar'' phase $P_I$ to undergo a reentrant pseudo-spin canting transition to an incommensurate state $C_I$, with a finite out-of-plane pseudo-magnetization component, corresponding to an interlayer charge imbalance in regions between solitons. At $T>0$ the transition is in the 2d compressible Ising universality class, and at T=0, the quantum transition is in heretofore unexplored universality class. The striking experimental signatures are the universal nonlinear charge-voltage and in-plane field relations, and the divergence of the differential bilayer capacitance at the transition, resulting in a bilayer capacitor that spontaneously charges itself, even in the absence of an applied interlayer voltage.Comment: 4 RevTeX pgs, 1 eps figures, submitted to PR