We investigate the scenario of using the Automatic Repeat reQuest (ARQ) retransmission scheme for two-way video communications over wireless Rayleigh fading channels. Video quality is the major concern of these applications. We show that during the retransmissions of error packets, due to the reduced channel throughput, the video encoder buffer may fill-up quickly and cause the TMN8 rate-contro...

We derive an effective two-dimensional Hamiltonian to describe the low-energy electronic excitations of a graphite bilayer, which correspond to chiral quasiparticles with a parabolic dispersion exhibiting Berry phase 2pi. Its high-magnetic-field Landau-level spectrum consists of almost equidistant groups of fourfold degenerate states at finite energy and eight zero-energy states. This can be tr...

We show that for a generic conformal metric perturbation of compact hyperbolic 3-manifold $\Sigma$ with Betti number $b_1$, the order vanishing Ruelle zeta function at zero equals $4-b_1$, while in case it is equal to $4-2b_1$. This contrast 2-dimensional where topological invariant. The proof uses microlocal approach dynamical functions, giving geometric description generalized Pollicott-Ruell...

A frame $L$ is called {it coz-dense} if $Sigma_{coz(alpha)}=emptyset$ implies $alpha=mathbf 0$. Let $mathcal RL$ be the ring of real-valued continuous functions on a coz-dense and completely regular frame $L$. We present a description of the socle of the ring $mathcal RL$ based on minimal ideals of $mathcal RL$ and zero sets in pointfree topology. We show that socle of $mathcal RL$ is an essent...

Article history: Received 4 August 2008 Received in revised form 12 December 2008 Accepted 13 December 2008 MSC: 54E05 54D35 54G05

Let $M_R$ be a non-zero‎ ‎module and ${mathcal F}‎: ‎sigma[M_R]times sigma[M_R]‎ ‎rightarrow$ Mod-$Bbb{Z}$ a bifunctor‎. ‎The‎ ‎$mathcal{F}$-reversibility of $M$ is defined by ${mathcal‎ ‎F}(X,Y)=0 Rightarrow {mathcal F}(Y,X)=0$ for all non-zero $X,Y$‎ ‎in $sigma[M_R]$‎. ‎Hom (resp‎. ‎Rej)-reversibility of $M$ is‎ ‎characterized in different ways‎. ‎Among other things‎, ‎it is shown‎ ‎th...

Just as fermion zero modes can alter the degeneracy and quantum numbers of a soliton, fermion energies can affect the form and stability of a nontopological soliton. We discuss the kink in a two-dimensional linear sigma model, and show that, when coupled to fermions, the kink is no longer an extremum of the energy functional. The kink in this model possesses many similarities to the electroweak...

An unambiguous definition of the electromagnetic spatial densities for a spin-1/2 system is proposed and worked out in zero average momentum frame moving frames. The obtained results are compared with traditional terms three-dimensional Fourier transforms form factors Breit frame.

We define new topological theories related to sigma models whose target space is a 7 dimensional manifold of G2 holonomy. We show how to define the topological twist and identify the BRST operator and the physical states. Correlation functions at genus zero are computed and related to Hitchin’s topological action for three-forms. We conjecture that one can extend this definition to all genus an...