Lattice Thermal Conductivity of Quartz at High Pressure and Temperature from the Boltzmann Transport Equation

The thermal conductivities along the basal and hexagonal directions of α-quartz silica, the low-temperature form of crystalline SiO2, are predicted from the solution of the Boltzmann transport equation combined with the van Beest, Kramer, and van Santen potential for the temperature up to 900 K and the pressure as high as 4 GPa. The thermal conductivities at atmospheric pressure, which show a negative and nonlinear dependence on temperature, are in reasonable agreement with the experimental data. The influence of pressure on thermal conductivity is positive and linear. The pressure (P) and temperature (T) dependences of the thermal conductivity (λ) in basal and hexagonal directions are fitted to a function of the form λ = (b + cP) Ta. The thermal conductivity, influenced by temperature and pressure, is analyzed based on phonon properties, including spectral thermal conductivity, dispersion relation, phonon density of states, phonon lifetime, and phonon probability density distribution function

Microscopic Electron Models with Exact SO(5) Symmetry

We construct a class of microscopic electron models with exact SO(5) symmetry between antiferromagnetic and d-wave superconducting ground states. There is an exact one-to-one correspondence between both single-particle and collective excitations in both phases. SO(5) symmetry breaking terms can be introduced and classified according to irreducible representations of the exact SO(5) algebra. The resulting phase diagram and collective modes are identical to that of the SO(5) nonlinear sigma model.Comment: 5 pages, LATEX, 4 eps fig

The American Customer Satisfaction Index: Nature, Purpose, and Findings

The American Customer Satisfaction Index (ACSI) is a new type of market-based performance measure for firms, industries, economic sectors, and national economies. The authors discuss the nature and purpose of ACSI and explain the theory underlying the ACSI model, the nation-wide survey methodology used to collect the data, and the econometric approach employed to estimate the indices. They also illustrate the use of ACSI in conducting benchmarking studies, both cross-sectionally and over time. The authors find customer satisfaction to be greater for goods than for services and, in turn, greater for services than for government agencies, as well as find cause for concern in the observation that customer satisfaction in the United States is declining, primarily because of decreasing satisfaction with services. The authors estimate the model for the seven major economic sectors for which data are collected. Highlights of the findings include that (1) customization is more important than reliability in determining customer satisfaction, (2) customer expectations play a greater role in sectors in which variance in production and consumption is relatively low, and (3) customer satisfaction is more quality-driven than value- or price-driven. The authors conclude with a discussion of the implications of ACSI for public policymakers, managers, consumers, and marketing in general

Customer satisfaction and price tolerance

This study investigates the association between customer satisfaction and willingness-to-pay or price tolerance. The goal is not only to determine whether the association between customer satisfaction and price tolerance is positive or negative but also to gauge the degree of association. The Swedish Customer Satisfaction Barometer provides the data. The empirical analysis indicates a negative association between the level of customer satisfaction provided by the firm and the degree of price tolerance exhibited by its customers. However, a positive association is found between year-to-year changes in the levels of customer satisfaction and price tolerance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47216/1/11002_2004_Article_BF00435742.pd

Cross-category variation in customer satisfaction and retention

Perceived quality, expectations, customer satisfaction, and effect of customer satisfaction on repurchase likelihood are found to be higher for products than for services, but repurchase likelihood for products is lower. Retailers have the highest repurchase likelihood and score lowest on the other variables. A set of relevant category characteristics is used to further understand variation in both the levels of these variables and their relationships. Quality, expectations, satisfaction, and satisfaction's effect on repurchase are higher — and repurchase likelihood is lower — when competition, differentiation, involvement, or experience is high and when switching costs, difficulty of standardization, or ease of evaluating quality is low.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47140/1/11002_2004_Article_BF00993955.pd

Search for the \pi Resonance in Two Particle Tunneling Experiments of YBCO Superconductors

A recent theory of the resonant neutron scattering peaks in YBCO superconductors predicts the existence of a sharp spin triplet two particle collective mode (the ``\pi resonance") in the normal state. In this paper, we propose an experiment in which the \pi resonance could be probed directly in a two particle tunneling measurement.Comment: 10 pages, LATEX , 3 ps figure

Graph Partitioning Induced Phase Transitions

We study the percolation properties of graph partitioning on random regular graphs with N vertices of degree $k$. Optimal graph partitioning is directly related to optimal attack and immunization of complex networks. We find that for any partitioning process (even if non-optimal) that partitions the graph into equal sized connected components (clusters), the system undergoes a percolation phase transition at $f=f_c=1-2/k$ where $f$ is the fraction of edges removed to partition the graph. For optimal partitioning, at the percolation threshold, we find $S \sim N^{0.4}$ where $S$ is the size of the clusters and $\ell\sim N^{0.25}$ where $\ell$ is their diameter. Additionally, we find that $S$ undergoes multiple non-percolation transitions for $f<f_c$

Observations of cosmic rays at high altitudes

Direct measurements of the momenta of cosmic-ray particles at an altitude of 30,000 feet have recently been reported

Ground state of a double-exchange system containing impurities: bounds of ferromagnetism

We study the boundary between ferromagnetic and non-ferromagnetic ground state of a double-exchange system with quenched disorder for arbitrary relation between Hund exchange coupling and electron band width. The boundary is found both from the solution of the Dynamical Mean Field Approximation equations and from the comparison of the energies of the saturated ferromagnetic and paramagnetic states. Both methods give very similar results. To explain the disappearance of ferromagnetism in part of the parameter space we derive from the double-exchange Hamiltonian with classical localized spins in the limit of large but finite Hund exchange coupling the $t-J$ model (with classical localized spins).Comment: 5 pages, 8 eps figures, latex; minor typos correcte