261,139 research outputs found
New Combinatorial Construction Techniques for Low-Density Parity-Check Codes and Systematic Repeat-Accumulate Codes
This paper presents several new construction techniques for low-density
parity-check (LDPC) and systematic repeat-accumulate (RA) codes. Based on
specific classes of combinatorial designs, the improved code design focuses on
high-rate structured codes with constant column weights 3 and higher. The
proposed codes are efficiently encodable and exhibit good structural
properties. Experimental results on decoding performance with the sum-product
algorithm show that the novel codes offer substantial practical application
potential, for instance, in high-speed applications in magnetic recording and
optical communications channels.Comment: 10 pages; to appear in "IEEE Transactions on Communications
The Role of Family-Based Designs in Genome-Wide Association Studies
Genome-Wide Association Studies (GWAS) offer an exciting and promising new
research avenue for finding genes for complex diseases. Traditional
case-control and cohort studies offer many advantages for such designs.
Family-based association designs have long been attractive for their robustness
properties, but robustness can mean a loss of power. In this paper we discuss
some of the special features of family designs and their relevance in the era
of GWAS.Comment: Published in at http://dx.doi.org/10.1214/08-STS280 the Statistical
Science (http://www.imstat.org/sts/) by the Institute of Mathematical
Statistics (http://www.imstat.org
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