Irregular polar coding for complexity-constrained lightwave systems

Next-generation fiber-optic communications call for ultra-reliable forward error correction codes that are capable of low-power and low-latency decoding. In this paper, we propose a new class of polar codes, whose polarization units are irregularly pruned to reduce computational complexity and decoding latency without sacrificing error correction performance. We then experimentally demonstrate that the proposed irregular polar codes can outperform state-of-the-art low-density parity-check (LDPC) codes, while decoding complexity and latency can be reduced by at least 30% and 70%, respectively, versus regular polar codes, while also obtaining a marginal performance improvement

Irregular Polar Coding for Multi-Level Modulation in Complexity-Constrained Lightwave Systems

We introduce novel irregular polar codes, which extend the regular polar coding by flexible polarization pruning. We experimentally demonstrate that the proposed polar codes outperform state-of-the-art LDPC codes, while the computational complexity in encoding and decoding can be significantly reduced by at least 30% over the regular polar codes with a marginal performance improvement

Population genetic structure of Microdochium majus and Microdochium nivale associated with Fusarium head blight of wheat in Hokkaido, Japan

Microdochium majus and Microdochium nivale are two of fungal pathogens that cause Fusarium head blight (FHB) in wheat, and have also caused pink snow mold in eastern Hokkaido, Japan. With the aim of assessing levels of genetic variation and population structure, 172 isolates of these Microdochium species obtained from five populations of infected wheat seeds were first classified into each species using polymerase chain reaction (PCR) amplification with specific primers. In total 165 (95.9 % of all isolates) and seven isolates (six of Tokachi populations and one of Abashiri populations) were identified as M. majus and M. nivale, respectively, indicating that M. majus was predominant and the main causal pathogen of FHB in this area. Inter-simple sequence repeat (ISSR) analysis showed that the total genetic diversity was 0.023 when estimated by Nei's gene diversity index within the five populations dominated by M. majus. An AMOVA analysis also showed that 86.74 % of the total genetic variation was within populations and 13.26 % among populations. These results indicated that little genetic differentiation occurred among the five populations of M. majus. Based on the unweighted pair group method of cluster analysis using the ISSR data, all isolates were identified as one of eight haplotypes in M. majus or six haplotypes in M. nivale, allowing the construction of a dendrogram with two clades corresponding to each species. There was no correlation between the clustering of isolates and their geographic distribution on the tree. These findings show that migration is likely playing an important role in the population biology of M. majus, providing some support for the prediction of epidemics of fungicide resistant strains within populations of the FHB pathogen