70,708 research outputs found
Patient delays in seeking help at the onset of rheumatoid arthritis: the problem, its causes and potential solutions
Rheumatoid arthritis (RA) is a chronic inflammatory disease for which early treatment is vital to limit long term joint damage. However, people often delay in seeking medical help at the onset of RA symptoms. The early interpretation of symptoms and the process of making sense of symptoms impacts on both help-seeking decision-making and self-management. Furthermore, the general public’s perceptions and knowledge of RA may also affect the way that symptoms are interpreted. Examining the psychology behind early symptom interpretation, the barriers to help-seeking behaviour and investigating the public understandings of RA, can help us understand how decisions are made and guide us in developing interventions which encourage people to seek help promptly at the onset of RA
Barrier modification in sub-barrier fusion reactions using Wong formula with Skyrme forces in semiclassical formalism
We obtain the nuclear proximity potential by using semiclassical extended
Thomas Fermi (ETF) approach in Skyrme energy density formalism (SEDF), and use
it in the extended -summed Wong formula under frozen density
approximation. This method has the advantage of allowing the use of different
Skyrme forces, giving different barriers. Thus, for a given reaction, we could
choose a Skyrme force with proper barrier characteristics, not-requiring extra
``barrier lowering" or ``barrier narrowing" for a best fit to data. For the
Ni+Mo reaction, the -summed Wong formula, with effects of
deformations and orientations of nuclei included, fits the fusion-evaporation
cross section data exactly for the force GSkI, requiring additional barrier
modifications for forces SIII and SV. However, the same for other similar
reactions, like Ni+Ni, fits the data best for SIII force.
Hence, the barrier modification effects in -summed Wong expression
depends on the choice of Skyrme force in extended ETF method.Comment: INPC2010, Vancouver, CANAD
Asymptotic Performance of Linear Receivers in MIMO Fading Channels
Linear receivers are an attractive low-complexity alternative to optimal
processing for multi-antenna MIMO communications. In this paper we characterize
the information-theoretic performance of MIMO linear receivers in two different
asymptotic regimes. For fixed number of antennas, we investigate the limit of
error probability in the high-SNR regime in terms of the Diversity-Multiplexing
Tradeoff (DMT). Following this, we characterize the error probability for fixed
SNR in the regime of large (but finite) number of antennas.
As far as the DMT is concerned, we report a negative result: we show that
both linear Zero-Forcing (ZF) and linear Minimum Mean-Square Error (MMSE)
receivers achieve the same DMT, which is largely suboptimal even in the case
where outer coding and decoding is performed across the antennas. We also
provide an approximate quantitative analysis of the markedly different behavior
of the MMSE and ZF receivers at finite rate and non-asymptotic SNR, and show
that while the ZF receiver achieves poor diversity at any finite rate, the MMSE
receiver error curve slope flattens out progressively, as the coding rate
increases.
When SNR is fixed and the number of antennas becomes large, we show that the
mutual information at the output of a MMSE or ZF linear receiver has
fluctuations that converge in distribution to a Gaussian random variable, whose
mean and variance can be characterized in closed form. This analysis extends to
the linear receiver case a well-known result previously obtained for the
optimal receiver. Simulations reveal that the asymptotic analysis captures
accurately the outage behavior of systems even with a moderate number of
antennas.Comment: 48 pages, Submitted to IEEE Transactions on Information Theor
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