Effective Dielectric Tensor for Electromagnetic Wave Propagation in Random Media

We derive exact strong-contrast expansions for the effective dielectric tensor \epeff of electromagnetic waves propagating in a two-phase composite random medium with isotropic components explicitly in terms of certain integrals over the $n$-point correlation functions of the medium. Our focus is the long-wavelength regime, i.e., when the wavelength is much larger than the scale of inhomogeneities in the medium. Lower-order truncations of these expansions lead to approximations for the effective dielectric constant that depend upon whether the medium is below or above the percolation threshold. In particular, we apply two- and three-point approximations for \epeff to a variety of different three-dimensional model microstructures, including dispersions of hard spheres, hard oriented spheroids and fully penetrable spheres as well as Debye random media, the random checkerboard, and power-law-correlated materials. We demonstrate the importance of employing $n$-point correlation functions of order higher than two for high dielectric-phase-contrast ratio. We show that disorder in the microstructure results in an imaginary component of the effective dielectric tensor that is directly related to the {\it coarseness} of the composite, i.e., local volume-fraction fluctuations for infinitely large windows. The source of this imaginary component is the attenuation of the coherent homogenized wave due to scattering. We also remark on whether there is such attenuation in the case of a two-phase medium with a quasiperiodic structure.Comment: 40 pages, 13 figure

Nuclear isotope thermometry

We discuss different aspects which could influence temperatures deduced from experimental isotopic yields in the multifragmentation process. It is shown that fluctuations due to the finite size of the system and distortions due to the decay of hot primary fragments conspire to blur the temperature determination in multifragmentation reactions. These facts suggest that caloric curves obtained through isotope thermometers, which were taken as evidence for a first-order phase transition in nuclear matter, should be investigated very carefully.Comment: 9 pages, 7 figure

CD4+ T-cell responses to Epstein-Barr virus nuclear antigen EBNA1 in Chinese populations are highly focused on novel C-terminal domain-derived epitopes

Epstein-Barr virus nuclear antigen EBNA1, the one viral protein uniformly expressed in nasopharyngeal carcinoma (NPC), represents a prime target for T-cell-based immunotherapy. However, little is known about the EBNA1 epitopes, particularly CD4 epitopes, presented by HLA alleles in Chinese people, the group at highest risk for NPC. We analyzed the CD4$^+$ T-cell responses to EBNA1 in 78 healthy Chinese donors and found marked focusing on a small number of epitopes in the EBNA1 C-terminal region, including a DP5- restricted epitope that was recognized by almost half of the donors tested and elicited responses able to recognize EBNA1-expressing, DP5-positive target cells

Specific heat at constant volume in the thermodynamic model

A thermodynamic model for multifragmentation which is frequently used appears to give very different values for specific heat at constant volume depending upon whether canonical or grand canonical ensemble is used. The cause for this discrepancy is analysed.Comment: Revtex, 7 pages including 4 figure

Magnifying perfect lens and superlens design by coordinate transformation

The coordinate transformation technique is applied to the design of perfect lenses and superlenses. In particular, anisotropic metamaterials that magnify two-dimensional planar images beyond the diffraction limit are designed by the use of oblate spheroidal coordinates. The oblate spheroidal perfect lens or superlens can naturally be used in reverse for lithography of planar subwavelength patterns.Comment: 8 pages, 8 figures, v2: submitted, v3: accepted by Physical Review

Coherent Quantum-Noise Cancellation for Optomechanical Sensors

Using a flowchart representation of quantum optomechanical dynamics, we design coherent quantum-noise-cancellation schemes that can eliminate the back-action noise induced by radiation pressure at all frequencies and thus overcome the standard quantum limit of force sensing. The proposed schemes can be regarded as novel examples of coherent feedforward quantum control.Comment: 4 pages, 5 figures, v2: accepted by Physical Review Letter

A semianalytical approach to spatial averaging of hydraulic conductivity in heterogeneous aquifers

Numerical models of groundwater flow require hydraulic conductivity values to be assigned to the grid blocks covering the flow domain. However, field-measured conductivities tend to be measured at a different scale (usually smaller) than that of the grid blocks. The present paper describes a novel approach for upscaling field values to block-scale, which combines the rigorous result of small-value perturbation analysis with a plausible generalization of the first-order results to large variance. Also the correlation lengths are assumed to be comparable to block size. Steady-state flow through a block of stochastically heterogeneous medium with constant hydraulic head values at the two opposite sides is analyzed. An upscaling rule and relationship is obtained between the local-scale hydraulic conductivity and the expected mean and variance of block-scale conductivity, where the block size is comparable with the correlation scale of the local conductivity field. The rather simple expressions obtained are validated using data from numerical experiments. Furthermore, a generalized spatial power-averaging method to calculate the block-scale conductivity from values of local-scale conductivity is developed, in which the exponent value is given as a function of the ratios of flow domain dimensions to the respective correlation lengths

What works in changing energy-using behaviours in the home? A rapid evidence assessment

RAND Europe was commissioned by the Department of Energy & Climate Change (DECC) to undertake a Rapid Evidence Assessment* to understand “What works in changing energy-using behaviours in the home?”. The main objective was to answer this question by systematically reviewing the evidence around domestic behaviour change, with a particular focus on international evidence.In order to identify relevant studies, and avoid overlap with other previous evidence reviews, a set of search criteria was established. For inclusion, studies must:• Target energy-using behaviours in the home.• Consider at least one intervention.**• Go beyond the use of direct feedback on past energy use and pricing strategies to shift or reduce demand; and consider behaviour beyond one-off purchasing decisions (such as the installation of insulation or the purchase of energy-efficient appliances).• Measure a behaviour change in a real-world setting, either observed or self-reported.• Make a comparison between groups (e.g. between treatment and control groups), or across different time periods.No restrictions were applied regarding sample size; and both quantitative and qualitative studies were included.This report draws on 48 behaviour change programmes identified and selected through a systemic search process. These programmes involve a wide range of innovative approaches (such as the provision of Home Energy Reports that compare households’ consumption with their neighbours’) as well as more traditional approaches (including advertising campaigns)