335 research outputs found
Redundancy Allocation of Partitioned Linear Block Codes
Most memories suffer from both permanent defects and intermittent random
errors. The partitioned linear block codes (PLBC) were proposed by Heegard to
efficiently mask stuck-at defects and correct random errors. The PLBC have two
separate redundancy parts for defects and random errors. In this paper, we
investigate the allocation of redundancy between these two parts. The optimal
redundancy allocation will be investigated using simulations and the simulation
results show that the PLBC can significantly reduce the probability of decoding
failure in memory with defects. In addition, we will derive the upper bound on
the probability of decoding failure of PLBC and estimate the optimal redundancy
allocation using this upper bound. The estimated redundancy allocation matches
the optimal redundancy allocation well.Comment: 5 pages, 2 figures, to appear in IEEE International Symposium on
Information Theory (ISIT), Jul. 201
Spin polarisabilities of the nucleon at NLO in the chiral expansion
We present a calculation of the fourth-order (NLO) contribution to
spin-dependent Compton scattering in heavy-baryon chiral perturbation theory,
and we give results for the four spin polarisabilities. No low-energy
constants, except for the anomalous magnetic moments of the nucleon, enter at
this order. For forward scattering the fourth-order piece of the spin
polarisability of the proton turns out to be almost twice the size of the
leading piece, with the opposite sign. This leads to the conclusion that no
prediction can currently be made for this quantity. For backward scattering the
fourth-order contribution is much smaller than the third-order piece which is
dominated by the anomalous scattering, and so cannot explain the discrepancy
between the CPT result and the current best experimental determination.Comment: 8 pages, 2 figures, revtex. Minor typos corrected and reference adde
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