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We establish existence, uniqueness, and arbitrary order Sobolev regularity results for the second order parabolic equations with measurable coefficients defined on the conic domains D of the typeWe obtain the regularity results by using a system of mixed weights consisting of appropriate powers of the distance to the vertex and of the distance to the boundary. We also provide the sharp ranges of admissible powers of the distance to the vertex and to the boundary.

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Effects of rearing density on growth and survival of the polychaete rockworm Marphysa sanguinea have been investigated in order to develop rearing techniques for this species. This study was examined over a nine-month period in the Fisheries Science and Technology Center of Pukyong National University. Three rockworm densities, 500, 1,000 and 2,000 worms•m -2 with weight ranges of < 0.5 g, 0.6-1.5 g, and 1.6-2.5 g, and the no feed control treatment, were stocked in triplicate 0.10 m 2 boxes with sand bottoms. Growth rates were checked with 15 randomly sampled rockworms from each box at months 3, 6 and 9. Results showed that SGRs in all treatments were higher during the first period (0-3 months) than the second (3-6 months) and third periods (6-9 months) for all treatment densities, while SGRs decreased with increasing density. However, survival and growth of worms at high density was not better than low density, but daily biomass production in medium and high density groups was 6.28 g m -2 day -1 for the rockworms of 0.6-1.5 g with 2,000 inds•m -2 , and 12.6 g m -2 day -1 for group between 1.6-2.5 g with 2,000 inds•m -2, and 14.7 g m -2 day -1 for the group of individuals <0.5 g with 1,000 inds•m -2 . Results showed that M. sanguinea can be one of the most suitable species to commercially exploit in a farming system. In particular, specified densities permit elevated pure production.