Effect of density and sex ratio on gonad development and spawning in the crayfish Procambarus llamasi

The effect of density and sex ratio on maturation and spawning in the crayfish Procambarus Ilamasi was evaluated during a 90-day study. Five stocking densities were tested: 10 org/m(2) (5 females/m(2)), 20 org/m(2) (15 females/m(2)), 34 org/m(2) (29 females/m(2)), 49 org/m(2) (44 females/m(2)) and 64 org/m(2) (59 females/m(2)), and five sex ratios (male/female) 1:1, 1:3, 1:6, 1:9 and 1:12. The Maturation Index (MI) results exhibited no significant differences between the high-density treatments, though there was a significant difference between these and the lowest density treatment. Females in the lowest density did not mature or spawn. The Gonadosomatic Index (GSI) showed no differences between densities, with high values in all treatments. Spawning increased in direct relation to density with the highest spawning percentage recorded in the highest density treatment. Density had a clear and significant effect on maturation and spawning in P. Ilamasi. (C) 2004 Elsevier B.V. All rights reserved

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We report on a8 50 GHz SIS heterodyne receiver employing a RF tuned niobium tunnel junction with a current density of 14kA/cm ,fabricatedona1mSi 3 N 4 supporting membrane. Since the mixer is designed to be operated well above the superconducting gap frequency of niobium (2#/h 690 GHz), special care has been taken to minimize niobium transmission line losses. Both Fourier Transform Spectrometer measurements of the direct detection performance and calculations of the IF output noise with the mixer operating in heterodyne mode, indicate an absorption loss in the niobium film of about 6.8 dB at8 22 GHz. These results are in reasonably good agreement with the loss predicted by the Mattis-Bardeen theory in the extreme anomalous limit