Chemical-potential flow equations for graphene with Coulomb interactions

We calculate the chemical potential dependence of the renormalized Fermi velocity and static dielectric function for Dirac quasiparticles in graphene nonperturbatively at finite temperature. By reinterpreting the chemical potential as a flow parameter in the spirit of the functional renormalization group (fRG) we obtain a set of flow equations, which describe the change of these functions upon varying the chemical potential. In contrast to the fRG the initial condition of the flow is nontrivial and has to be calculated separately. Our results confirm that the charge carrier density dependence of the Fermi velocity is negligible, validating the comparison of the fRG calculation at zero density of Bauer et al., Phys. Rev. B 92, 121409 (2015) with the experiment of Elias et al., Nat. Phys. 7, 701 (2011).Comment: 7 pages, 4 figure

Broadband cloaking with volumetric structures composed of two-dimensional transmission-line networks

The cloaking performance of two microwave cloaks, both based on the recently proposed transmission-line approach, are studied using commercial full-wave simulation software. The cloaks are shown to be able to reduce the total scattering cross sections of metallic objects of some restricted shapes and sizes. One of the studied cloaks is electrically small in diameter, and the other is electrically large, with the diameter equal to several wavelengths.Comment: 6 pages, 7 figure

The Success of Motion Pictures

THE SUCCESS OF MOTION PICTURES – AN ECONOMIC GAMBLE: SELECTED MOVIE EXPLOITATION PHENOMENA More than 5,000 marketable movies are produced worldwide every year - a risky economic gamble running into billions. Despite the potential risk of commercial failure, film producers still try to achieve outstanding box-office results. There are also special movies that are able to preserve or even increase their intrinsic value due to the longevity of their commercial success. This article focuses on distinctive movie exploitation phenomena, which can be observed worldwide. These phenomena show the unpredictability of film success due to the fact that the cycles, the duration, and the progress of film exploitation are unforeseeable. MythSuccess is the big myth of the international film industry: on the one hand enormous profits, glamour, film stars, red carpet shows at Cannes, Berlin, and Venice - the big film festivals. And as climax - the Oscars in..

Event-based analysis: Identifying and sequencing prehistoric activities in buried palimpsests. An example from Lake George, Australia.

This thesis presents a new methodology for sequencing behavioural events in sub-surface stone artefact assemblages. While methods have been previously presented for the identification of activities, often termed 'moments in time', these studies have focused on temporally bounded living floors, usually in cave environments. Buried assemblages in open landscapes often do not retain such coherence, and so the development of a methodology for identifying and sequencing behavioural events in mixed assemblages is needed. This study develops a method, here termed event-based analysis (EBA), for the temporal sequencing of discrete activities in undifferentiated stratigraphies with vertically distributed artefactual deposits, which then allows comparisons of prehistoric activities to be made across space and time. Event-based analysis draws on several methods previously presented in the literature, principally RMU analysis, life-history framework and refitting for the reunification of refuse from single stone-working activities and the construction of inferences regarding the reduction and flow of stone though a site. Event-based analysis relies on these methods for identifying and understanding discrete stone working activities. EBA then extends the applicability of these methods to the analysis of temporally deep buried assemblages by providing a method whereby identified knapping and discard events can be sequenced. This shifts the unit of analysis in buried palimpsests from the assemblage to the event, and allows comparisons to be built over time and space from this behaviourally meaningful unit. This thesis is concerned with how archaeologists make inferences about prehistoric cultures from the archaeological record. To this end, a new methodological framework, event-based analysis, is advanced which both guides the construction of evidence-led inferences regarding prehistoric behaviour, and promotes the comparison of those behavioural inferences for the purpose of producing generalisations concerning use of place (Schiffer 2011). Using EBA, this project examines the configuration of foraging economies and technologies in the Lake George area of south-eastern Australia. A detailed place-use history is built from the comparison of discrete knapping and discard events over time and space. This thesis thus contributes to the development of archaeological methodologies which seek to build detailed and meaningful ‘thick descriptions’ (sensu Geertz (1973)) which are firmly grounded in the evidence examined. The aim is to provide detailed descriptions of the human activities which produced the stone artefact assemblages; it is to elucidate the ‘delicacy of its distinctions, not the sweep of its abstractions’ (Geertz 1973:25)

Integral equation mei applied to three-dimensional arbitrary surfaces

The authors present a new formulation of the integral equation of the measured equation of invariance (MEI) as a confined field integral equation discretised by the method of moments, in which the use of numerically derived testing functions results in an approximately sparse linear system with storage memory requirements and a CPU time for computing the matrix coefficients proportional to the number of unknowns.Peer ReviewedPostprint (published version

Spatial Multiplexing of QPSK Signals with a Single Radio: Antenna Design and Over-the-Air Experiments

The paper describes the implementation and performance analysis of the first fully-operational beam-space MIMO antenna for the spatial multiplexing of two QPSK streams. The antenna is composed of a planar three-port radiator with two varactor diodes terminating the passive ports. Pattern reconfiguration is used to encode the MIMO information onto orthogonal virtual basis patterns in the far-field. A measurement campaign was conducted to compare the performance of the beam-space MIMO system with a conventional 2-by-?2 MIMO system under realistic propagation conditions. Propagation measurements were conducted for both systems and the mutual information and symbol error rates were estimated from Monte-Carlo simulations over the measured channel matrices. The results show the beam-space MIMO system and the conventional MIMO system exhibit similar finite-constellation capacity and error performance in NLOS scenarios when there is sufficient scattering in the channel. In comparison, in LOS channels, the capacity performance is observed to depend on the relative polarization of the receiving antennas.Comment: 31 pages, 23 figure

Analysis of microstrip antennas by multilevel matrix decomposition algorithm

Integral equation methods (IE) are widely used in conjunction with Method of Moments (MoM) discretization for the numerical analysis of microstrip antennas. However, their application to large antenna arrays is difficult due to the fact that the computational requirements increase rapidly with the number of unknowns N. Several techniques have been proposed to reduce the computational cost of IE-MoM. The Multilevel Matrix Decomposition Algorithm (MLMDA) has been implemented in 3D for arbitrary perfectly conducting surfaces discretized in Rao, Wilton and Glisson linear triangle basis functions . This algorithm requires an operation count that is proportional to N·log2N. The performance of the algorithm is much better for planar or piece-wise planar objects than for general 3D problems, which makes the algorithm particularly well-suited for the analysis of microstrip antennas. The memory requirements are proportional to N·logN and very low. The main advantage of the MLMDA compared with other efficient techniques to solve integral equations is that it does not rely on specific mathematical properties of the Green's functions being used. Thus, we can apply the method to interesting configurations governed by special Green's functions like multilayered media. In fact, the MDA-MLMDA method can be used at the top of any existing MoM code. In this paper we present the application to the analysis of large printed antenna arrays.Peer ReviewedPostprint (published version

Keldysh functional renormalization group for electronic properties of graphene

We construct a nonperturbative nonequilibrium theory for graphene electrons interacting via the instantaneous Coulomb interaction by combining the functional renormalization group method with the nonequilibrium Keldysh formalism. The Coulomb interaction is partially bosonized in the forward scattering channel resulting in a coupled Fermi-Bose theory. Quantum kinetic equations for the Dirac fermions and the Hubbard-Stratonovich boson are derived in Keldysh basis, together with the exact flow equation for the effective action and the hierarchy of one-particle irreducible vertex functions, taking into account a possible nonzero expectation value of the bosonic field. Eventually, the system of equations is solved approximately under thermal equilibrium conditions at finite temperature, providing results for the renormalized Fermi velocity and the static dielectric function, which extends the zero-temperature results of Bauer et al., Phys. Rev. B 92, 121409 (2015)