Fluctuation-induced noise in out-of-equilibrium disordered superconducting films

We study out-of-equilibrium transport in disordered superconductors close to the superconducting transition. We consider a thin film connected by resistive tunnel interfaces to thermal reservoirs having different chemical potentials and temperatures. The nonequilibrium longitudinal current-current correlation function is calculated within the nonlinear sigma model description and nonlinear dependence on temperatures and chemical potentials is obtained. Different contributions are calculated, originating from the fluctuation-induced suppression of the quasiparticle density of states, Maki- Thompson and Aslamazov-Larkin processes. As a special case of our results, close-to-equilibrium we obtain the longitudinal ac conductivity using the fluctuation-dissipation theorem

Effective partitioning method for computing weighted Moore-Penrose inverse

We introduce a method and an algorithm for computing the weighted Moore-Penrose inverse of multiple-variable polynomial matrix and the related algorithm which is appropriated for sparse polynomial matrices. These methods and algorithms are generalizations of algorithms developed in [M.B. Tasic, P.S. Stanimirovic, M.D. Petkovic, Symbolic computation of weighted Moore-Penrose inverse using partitioning method, Appl. Math. Comput. 189 (2007) 615-640] to multiple-variable rational and polynomial matrices and improvements of these algorithms on sparse matrices. Also, these methods are generalizations of the partitioning method for computing the Moore-Penrose inverse of rational and polynomial matrices introduced in [P.S. Stanimirovic, M.B. Tasic, Partitioning method for rational and polynomial matrices, Appl. Math. Comput. 155 (2004) 137-163; M.D. Petkovic, P.S. Stanimirovic, Symbolic computation of the Moore-Penrose inverse using partitioning method, Internat. J. Comput. Math. 82 (2005) 355-367] to the case of weighted Moore-Penrose inverse. Algorithms are implemented in the symbolic computational package MATHEMATICA

BER Performance of IM/DD FSO System with OOK using APD Receiver

In this paper, the performance of intensity-modulated with direct detection (IM/DD) free space optical (FSO) system using the on-off keying (OOK) and avalanche photodiode (APD) receiver is observed. The gamma-gamma model is used to describe the effect of atmospheric turbulence since it provides good agreement in the wide range of atmospheric conditions. In addition, the same FSO system with equal gain combining applied at the reception is analyzed. After theoretical derivation of the expression for the bit error rate (BER), the numerical integration with previously specified relative calculation error is performed. Numerical results are presented and confirmed by Monte Carlo simulations. The effects of the FSO link and receiver parameters on the BER performance are discussed. The results illustrate that the optimal APD gain in the minimum BER sense depends considerably on the link distance, atmospheric turbulence strength and receiver temperature. In addition, the value of this optimal gain is slightly different in the case of spatial diversity application compared with single channel reception

Order and Creep in Flux Lattices and CDWs Pinned by Planar Defects

The influence of randomly distributed point impurities \emph{and} planar defects on the order and transport in type-II superconductors and related systems is considered theoretically. For planar defects of identical orientation the flux line lattice exhibits a new glassy phase dominated by the planar defects with a finite compressibility, a transverse Meissner effect, large sample to sample fuctuations of the susceptibility and an exponential decay of translational long range order. The flux creep resistivity for currents $J$ parallel to the defects is $\rho(J)\sim \exp-(J_0/J)^{3/2}$ . Strong disorder enforces an array of dislocations to relax shear strain

Ferromagnetic resonance with a magnetic Josephson junction

We show experimentally and theoretically that there is a coupling via the Aharonov-Bohm phase between the order parameter of a ferromagnet and a singlet, s-wave, Josephson supercurrent. We have investigated the possibility of measuring the dispersion of such spin waves by varying the magnetic field applied in the plane of the junction and demonstrated the electromagnetic nature of the coupling by the observation of magnetic resonance side-bands to microwave induced Shapiro steps.Comment: 6 pages, 5 figure

Human dimension of strategic partnerships

This paper aims to point to the widespread practice of neglecting behavioral aspects of different forms of fusions and integrations of enterprises that have emerged in the process of privatization through strategic partnerships with foreign companies among Serbian enterprises. The initial hypothesis in this paper is that the process of privatization, restructuring and transformation in Serbian enterprises cannot be completely successful and equally advantageous for all the subjects involved if there is no concern for human dimension of these processes. Without this concern there is a possibility for behavioral problems to arise, and the only way to resolve them is through post festum respecting and introducing elements that should never have been neglected in the first place. This paper refers to the phenomenon of collision of cultures and the ways of resolving it while forming strategic partnerships

COMPUTER TOOLS FOR SOLVING MATHEMATICAL PROBLEMS: A REVIEW

The rapid development of digital computer hardware and software has had a dramatic influence on mathematics, and contrary. The advanced hardware and modern sophistical software such as computer visualization, symbolic computation, computerassisted proofs, multi-precision arithmetic and powerful libraries, have provided resolving many open problems, a huge very difficult mathematical problems, and discovering new patterns and relationships, far beyond a human capability. In the first part of the paper we give a short review of some typical mathematical problems solved by computer tools. In the second part we present some new original contributions, such as intriguing consequence of the presence of roundoff errors, distribution of zeros of random polynomials, dynamic study of zero-finding methods, a new three-point family of methods for solving nonlinear equations and two algorithms for the inclusion of a simple complex zero of a polynomial