A Generalised Sidelobe Canceller Architecture Based on Oversampled Subband Decompositions

Adaptive broadband beamforming can be performed in oversampled subband signals, whereby an independent beamformer is operated in each frequency band. This has been shown to result in a considerably reduced computational complexity. In this paper, we primarily investigate the convergence behaviour of the generalised sidelobe canceller (GSC) based on normalised least mean squares algorithm (NLMS) when operated in subbands. The minimum mean squared error can be limited, amongst other factors, by the aliasing present in the subbands. With regard to convergence speed, there is strong indication that the subband-GSC converges faster than a fullband counterpart of similar modelling capabilities. Simulations are presented

Topological partition relations to the form omega^*-> (Y)^1_2

Theorem: The topological partition relation omega^{*}-> (Y)^{1}_{2} (a) fails for every space Y with |Y| >= 2^c ; (b) holds for Y discrete if and only if |Y| <= c; (c) holds for certain non-discrete P-spaces Y ; (d) fails for Y= omega cup {p} with p in omega^{*} ; (e) fails for Y infinite and countably compact

Dephasing in (Ga,Mn)As nanowires and rings

To understand quantum mechanical transport in ferromagnetic semiconductor the knowledge of basic material properties like phase coherence length and corresponding dephasing mechanism are indispensable ingredients. The lack of observable quantum phenomena prevented experimental access to these quantities so far. Here we report about the observations of universal conductance fluctuations in ferromagnetic (Ga,Mn)As. The analysis of the length and temperature dependence of the fluctuations reveals a T^{-1} dependence of the dephasing time.Comment: 5 pages, 4 figure

Effect of the Haar measure on the finite temperature effective potential of SU(2)SU(2) Yang-Mills theory

Including the Haar measure we show that the effective potential of the regularized SU(2) Yang-Mills theory has a minimum at vanishing Wilson-line $W=0$ for strong coupling, whereas it develops two degenerate minima close to $W=\pm 1$ for weak coupling. This suggests that the non-abelian character of $SU(2)$ as contained in the Haar measure might be responsible for confinement.Comment: 3 pages, LATEX, 1 figure, figure available upon reques

Non-Markovian master equation for a damped oscillator with time-varying parameters

We derive an exact non-Markovian master equation that generalizes the previous work [Hu, Paz and Zhang, Phys. Rev. D {\bf 45}, 2843 (1992)] to damped harmonic oscillators with time-varying parameters. This is achieved by exploiting the linearity of the system and operator solution in Heisenberg picture. Our equation governs the non-Markovian quantum dynamics when the system is modulated by external devices. As an application, we apply our equation to parity kick decoupling problems. The time-dependent dissipative coefficients in the master equation are shown to be modified drastically when the system is driven by $\pi$ pulses. For coherence protection to be effective, our numerical results indicate that kicking period should be shorter than memory time of the bath. The effects of using soft pulses in an ohmic bath are also discussed

Monte Carlo simulations reveal the straightening up of an end-grafted flexible chain with a rigid side chain

We have studied the conformational properties of a flexible end-grafted chain (length $N$) with a rigid side chain (length $S$) by means of Monte Carlo simulations. Depending on the lengths $N$ and $S$ and the branching site, $b$, we observe a considerable straightening of the flexible backbone as quantified via the gyration tensor. For $b=N$, i.e. when attaching the side chain to the free end of the flexible backbone, the effect was strongest

Human complement factor H

We isolated cDNA clones coding for the functionally important tryptic N-terminal38- kDa fragment of human complement control protein factor H using polyclonal and monoclonal antibodies to screen a human liver cDNA library cloned in a bacterial expression vector, PEX-1. By testing the reactivity of antibodies specific for the recombinant proteins produced by individual clones with proteolytic fragments of serum H the exact position of these cDNA clones within H was mapped. One clone, H-19, coding for the 38-kDa fragment of H was sequenced and found to code for 289 amino acids derived from the 38-kDa N-terminal fragment as well as for the first 108 amino acids belonging to the complementary 142-kDa tryptic fragment. The derived protein sequence could be arranged in 6 highly homologous repeats of about 60 amino acids each, the homology between the repeats being determined by the characteristic position of cysteine, proline, glycine, tyrosine and tryptophane residues. The region coding for the epitope recognized by one of our monoclonal antibodies was localized by subcloning restriction fragments of H-19 into the expression plasmid and testing for the expression of this epitope

Entanglement of mechanical oscillators coupled to a non-equilibrium environment

Recent experiments aim at cooling nanomechanical resonators to the ground state by coupling them to non-equilibrium environments in order to observe quantum effects such as entanglement. This raises the general question of how such environments affect entanglement. Here we show that there is an optimal dissipation strength for which the entanglement between two coupled oscillators is maximized. Our results are established with the help of a general framework of exact quantum Langevin equations valid for arbitrary bath spectra, in and out of equilibrium. We point out why the commonly employed Lindblad approach fails to give even a qualitatively correct picture

Coherently controlled entanglement generation in a binary Bose-Einstein condensate

Considering a two-component Bose-Einstein condensate in a double-well potential, a method to generate a Bell state consisting of two spatially separated condensates is suggested. For repulsive interactions, the required tunnelling control is achieved numerically by varying the amplitude of a sinusoidal potential difference between the wells. Both numerical and analytical calculations reveal the emergence of a highly entangled mesoscopic state.Comment: 6 pages, 6 figures, epl2.cl