66 research outputs found

    A spherical perfect lens

    Full text link
    It has been recently proved that a slab of negative refractive index material acts as a perfect lens in that it makes accessible the sub-wavelength image information contained in the evanescent modes of a source. Here we elaborate on perfect lens solutions to spherical shells of negative refractive material where magnification of the near-field images becomes possible. The negative refractive materials then need to be spatially dispersive with ϵ(r)1/r\epsilon(r) \sim 1/r and μ(r)1/r\mu(r)\sim 1/r. We concentrate on lens-like solutions for the extreme near-field limit. Then the conditions for the TM and TE polarized modes become independent of μ\mu and ϵ\epsilon respectively.Comment: Revtex4, 9 pages, 2 figures (eps

    Distribution of reflection eigenvalues in many-channel chaotic cavities with absorption

    Full text link
    The reflection matrix R=S^{\dagger}S, with S being the scattering matrix, differs from the unit one, when absorption is finite. Using the random matrix approach, we calculate analytically the distribution function of its eigenvalues in the limit of a large number of propagating modes in the leads attached to a chaotic cavity. The obtained result is independent on the presence of time-reversal symmetry in the system, being valid at finite absorption and arbitrary openness of the system. The particular cases of perfectly and weakly open cavities are considered in detail. An application of our results to the problem of thermal emission from random media is briefly discussed.Comment: 4 pages, 2 figures; (Ref.[5b] added, appropriate modification in text

    Manifestation of photonic band structure in small clusters of spherical particles

    Get PDF
    We study the formation of the photonic band structure in small clusters of dielectric spheres. The first signs of the band structure, an attribute of an infinite crystal, can appear for clusters of 5 particles. Density of resonant states of a cluster of 32 spheres may exhibit a well defined structure similar to the density of electromagnetic states of the infinite photonic crystal. The resonant mode structure of finite-size aggregates is shown to be insensitive to random displacements of particles off the perfect lattice positions as large as half-radius of the particle. The results were obtained by an efficient numerical method, which relates the density of resonant states to the the scattering coefficients of the electromagnetic scattering problem. Generalized multisphere Mie (GMM) solution was used to obtain scattering matrix elements. These results are important to miniature photonic crystal design as well as understanding of light localization in dense random media.Comment: 4 pages, 2 figure

    Delay times and reflection in chaotic cavities with absorption

    Full text link
    Absorption yields an additional exponential decay in open quantum systems which can be described by shifting the (scattering) energy E along the imaginary axis, E+i\hbar/2\tau_{a}. Using the random matrix approach, we calculate analytically the distribution of proper delay times (eigenvalues of the time-delay matrix) in chaotic systems with broken time-reversal symmetry that is valid for an arbitrary number of generally nonequivalent channels and an arbitrary absorption rate 1/\tau_{a}. The relation between the average delay time and the ``norm-leakage'' decay function is found. Fluctuations above the average at large values of delay times are strongly suppressed by absorption. The relation of the time-delay matrix to the reflection matrix S^{\dagger}S is established at arbitrary absorption that gives us the distribution of reflection eigenvalues. The particular case of single-channel scattering is explicitly considered in detail.Comment: 5 pages, 3 figures; final version to appear in PRE (relation to reflection extended, new material with Fig.3 added, experiment cond-mat/0305090 discussed

    Variance of transmitted power in multichannel dissipative ergodic structures invariant under time reversal

    Full text link
    We use random matrix theory (RMT) to study the first two moments of the wave power transmitted in time reversal invariant systems having ergodic motion. Dissipation is modeled by a number of loss channels of variable coupling strength. To make a connection with ultrasonic experiments on ergodic elastodynamic billiards, the channels injecting and collecting the waves are assumed to be negligibly coupled to the medium, and to contribute essentially no dissipation. Within the RMT model we calculate the quantities of interest exactly, employing the supersymmetry technique. This approach is found to be more accurate than another method based on simplifying naive assumptions for the statistics of the eigenfrequencies and the eigenfunctions. The results of the supersymmetric method are confirmed by Monte Carlo numerical simulation and are used to reveal a possible source of the disagreement between the predictions of the naive theory and ultrasonic measurements.Comment: 10 pages, 2 figure

    Functional diversity of chemokines and chemokine receptors in response to viral infection of the central nervous system.

    Get PDF
    Encounters with neurotropic viruses result in varied outcomes ranging from encephalitis, paralytic poliomyelitis or other serious consequences to relatively benign infection. One of the principal factors that control the outcome of infection is the localized tissue response and subsequent immune response directed against the invading toxic agent. It is the role of the immune system to contain and control the spread of virus infection in the central nervous system (CNS), and paradoxically, this response may also be pathologic. Chemokines are potent proinflammatory molecules whose expression within virally infected tissues is often associated with protection and/or pathology which correlates with migration and accumulation of immune cells. Indeed, studies with a neurotropic murine coronavirus, mouse hepatitis virus (MHV), have provided important insight into the functional roles of chemokines and chemokine receptors in participating in various aspects of host defense as well as disease development within the CNS. This chapter will highlight recent discoveries that have provided insight into the diverse biologic roles of chemokines and their receptors in coordinating immune responses following viral infection of the CNS

    Track D Social Science, Human Rights and Political Science

    Full text link
    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

    Not Available

    No full text
    Not AvailableLoss of appealing quality characteristics and rapid desiccation within a short period after detaching from mother plants is one of the major problems in cut foliages. Effect of pulsing with benzyl adenine (BA), 8-Hydroxy Quinoline citrate (8-HQC) and sucrose on vase life of cut leaves of Asparagus setaceus syn. Plumosus was investigated. Two durations of pulsing viz., 12 and 24 h were employed. Pulsing for 12 h with BA (25 ppm) ? 8-HQC (200 ppm) ? 10 % sucrose resulted in higher fresh weight at senescence.The lowest physiological loss in weight was registered by the cut foliages pulsed for 24 h with BA (25 ppm) ? 8-HQC (200 ppm) ? 10 % sucrose. Pulsing the cut foliages for 24 h with BA (25 ppm) ? 8-HQC (200 ppm) ? 10 % sucrose resulted in the maximum uptake of water and registered the highest water balance. The lowest transpirational loss of water was found to be associated with foliages pulsed with 10 % sucrose alone for 24 h. The foliages pulsed with BA (25 ppm) ? 8-HQC (300 ppm) ? 10 % sucrose for 24 h registered lowest ratio between water loss and water uptake. Results suggest that application of 10 % sucrose?BA (25 ppm) ? 8-HQC (200 ppm) as a pulse treatment for 24 h can be recommended to prolong the postharvest life (28.50 days) through delayed leaf senescence and thus enhance the marketability of cut leaves of Asparagus setaceus syn. Plumosus.Not Availabl

    A model of fuel and energy sector contribution to economic growth

    Get PDF
    10.32479/ijeep.7849International Journal of Energy Economics and Policy9525-3

    Not Available

    No full text
    Not AvailableSecond International Conference on Agricultural & Horticultural Sciences” during 3 to 5 February 2014 at Radisson Blu Plaza Hotel, Hyderabad, IndiaNot Availabl
    corecore