On a q-analogue of the multiple gamma functions

A $q$-analogue of the multiple gamma functions is introduced, and is shown to satisfy the generalized Bohr-Morellup theorem. Furthermore we give some expressions of these function.Comment: 8 pages, AMS-Late

Shear thickening of cornstarch suspensions as a re-entrant jamming transition

We study the rheology of cornstarch suspensions, a dense system of non-Brownian particles that exhibits shear thickening, i.e. a viscosity that increases with increasing shear rate. Using MRI velocimetry we show that the suspension has a yield stress. From classical rheology it follows that as a function of the applied stress the suspension is first solid (yield stress), then liquid and then solid again when it shear thickens. The onset shear rate for thickening is found to depend on the measurement geometry: the smaller the gap of the shear cell, the lower the shear rate at which thickening occurs. Shear thickening can then be interpreted as the consequence of the Reynolds dilatancy: the system under flow wants to dilate but instead undergoes a jamming transition because it is confined, as confirmed by measurement of the dilation of the suspension as a function of the shear rate

Evidence for multiple impurity bands in sodium-doped silicon MOSFETs

We report measurements of the temperature-dependent conductivity in a silicon metal-oxide-semiconductor field-effect transistor that contains sodium impurities in the oxide layer. We explain the variation of conductivity in terms of Coulomb interactions that are partially screened by the proximity of the metal gate. The study of the conductivity exponential prefactor and the localization length as a function of gate voltage have allowed us to determine the electronic density of states and has provided arguments for the presence of two distinct bands and a soft gap at low temperature.Comment: 4 pages; 5 figures; Published in PRB Rapid-Communication

Use of 2G coated conductors for efficient shielding of DC magnetic fields

This paper reports the results of an experimental investigation of the performance of two types of magnetic screens assembled from YBa2Cu3O7-d (YBCO) coated conductors. Since effective screening of the axial DC magnetic field requires the unimpeded flow of an azimuthal persistent current, we demonstrate a configuration of a screening shell made out of standard YBCO coated conductor capable to accomplish that. The screen allows the persistent current to flow in the predominantly azimuthal direction at a temperature of 77 K. The persistent screen, incorporating a single layer of superconducting film, can attenuate an external magnetic field of up to 5 mT by more than an order of magnitude. For comparison purposes, another type of screen which incorporates low critical temperature quasi-persistent joints was also built. The shielding technique we describe here appears to be especially promising for the realization of large scale high-Tc superconducting screens.Comment: 8 pages, 3 figure

VITA Experiential, Service-Learning, Learned Competencies, And Changed Mindsets

The authors describe how Southern Utah University has integrated the U.S. Internal Revenue Service (IRS) Voluntary Income Tax Assistance (VITA) program as an experiential service-learning activity for over a decade and a half. First, we describe the value of experiential service-learning. Second, we detail the program, its oversight, its student volunteers, and its purposes. Third, we provide a quantitative assessment of professional competencies based on a sample of 29 recent VITA student volunteers. Fourth, we describe a qualitative analysis of VITA student volunteers perceptions of their participation using content analysis of written essays. And last, we provide a qualitative analysis of 71 tax-clients perceptions of their participation in the program, again using content analysis. Based on our experiences and these results, we conclude that the VITA program is demonstrably beneficial for the institutions social responsibility for benefitting both the student volunteers professional development and communitys lower-income tax filers

Production of scalar KKˉK\bar K molecules in ϕ\phi radiative decays

The potentialities of the production of the scalar $K\bar K$ molecules in the $\phi$ radiative decays are considered beyond the narrow resonance width approximation. It is shown that $BR(\phi\rightarrow\gamma f_0(a_0)\rightarrow\gamma\pi\pi(\pi\eta))\approx (1\div 2)\times 10^{-5}\ ,\BR(\phi\rightarrow\gamma (f_0+a_0)\rightarrow\gamma K^+K^-)\alt 10^{-6}$and$BR(\phi\rightarrow\gamma (f_0+a_0) \to \gamma K^0\bar K^0)\alt 10^{-8}$. The mass spectra in the$\pi\pi\ ,\ \pi\eta\ ,\ K^+K^-\ ,\ K^0\bar K^0$channels are calculated. The imaginary part of the amplitude$\phi\rightarrow\gamma f_0(a_0)$is calculated analytically. It is obtained the phase of the scalar resonance production amplitude that causes the interference patterns in the reaction$e^+e^-\rightarrow\gamma \pi^+\pi^-$in the$\phi$ meson mass region.Comment: 19 pages, revtex, 4 eps files of figure

Systematic Inclusion of High-Order Multi-Spin Correlations for the Spin-121\over2 XXZXXZ Models

We apply the microscopic coupled-cluster method (CCM) to the spin-$1\over2$ $XXZ$ models on both the one-dimensional chain and the two-dimensional square lattice. Based on a systematic approximation scheme of the CCM developed by us previously, we carry out high-order {\it ab initio} calculations using computer-algebraic techniques. The ground-state properties of the models are obtained with high accuracy as functions of the anisotropy parameter. Furthermore, our CCM analysis enables us to study their quantum critical behavior in a systematic and unbiased manner.Comment: (to appear in PRL). 4 pages, ReVTeX, two figures available upon request. UMIST Preprint MA-000-000

Stability of atomic clocks based on entangled atoms

We analyze the effect of realistic noise sources for an atomic clock consisting of a local oscillator that is actively locked to a spin-squeezed (entangled) ensemble of $N$ atoms. We show that the use of entangled states can lead to an improvement of the long-term stability of the clock when the measurement is limited by decoherence associated with instability of the local oscillator combined with fluctuations in the atomic ensemble's Bloch vector. Atomic states with a moderate degree of entanglement yield the maximal clock stability, resulting in an improvement that scales as $N^{1/6}$ compared to the atomic shot noise level.Comment: 4 pages, 2 figures, revtex

Production of the h_c and h_b and Implications for Quarkonium Spectroscopy

The recent observation of the h_c is an important test of QCD calculations and provides constraints on models of quarkonium spectroscopy. In this contribution I discuss some of these implications and describe methods to search for the h_c and h_b via radiative transitions and other means.Comment: Talk presented at the 1st Meeting of the APS Topical Group on Hadronic Physics (Fermilab, Oct 24-26, 2004), 4 pages, 1 figure, uses jpconf. References adde