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Abstruct-Intermodulation and harmonic distortion are calculated for a simple fiber-optic link with a representative set of link parameters and a variety of electrooptic modulators: simple Mach-Zehnder, linearized dual and triple Mach-Zehnder, simple directional coupler (two operating points), and linearized directional coupler with one and two dc electrodes. The resulting dynamic ranges, gains, and noise figures are compared for these modulators. A new definition of dynamic range is proposed to accommodate the more complicated variation of intermodulation with input power exhibited by linearized modulators. The effects of noise bandwidth, preamplifier distortion, and errors in modulator operating conditions are described.

Experiments were conducted on Palmer amaranth seeds collected in 2004 and 2006 from a natural population near Pendleton, SC, to determine the temperature and light requirements for germination of seeds retrieved from soil surface or from 10-cm depth in the field. A cyclic change in seed germination of Palmer amaranth in response to temperature and light occurred during a 12-mo after-ripening period. Freshly matured seeds collected in November required mean temperatures ≥ 25 C, and natural or red (R) light for increased germination. Following after-ripening in winter, seeds experienced a reduction in dormancy and germinated higher at 25 to 35 C mean compared with 10 to 15 C mean. With after-ripening for an additional 3 mo in May, seeds experienced a broadening of thermal range (10 to 40 C mean), and germination in natural light or R light was more than twice the germination in the absence of light. Fluctuating temperatures (7.5 C amplitude) improved germination over constant temperatures, except in summer and fall (9 and 12 mo after seed maturation). Exposure of seeds to high temperatures during summer caused secondary dormancy induction. Averaged over thermal amplitudes, seeds retrieved in fall required mean temperatures > 25 C for increased germination. Burial in spring for 3 to 6 mo induced seed dormancy, and the relative germination in fall (12 mo after seed maturation) was at least 50% higher for seeds retrieved from soil surface compared to seeds exhumed from 10-cm soil depth. Seeds retrieved in late summer and fall required natural light or R light for promoting germination, whereas far-red (FR) light or darkness inhibited germination. Furthermore, the effect of R and FR light was reversible, indicating a partially phytochrome-mediated germination response of Palmer amaranth seeds following 9 to 12 mo of after-ripening in the field.

Field experiments were conducted near Blackville, SC, and Tifton, GA, in 2004 and 2005, to evaluate the effect of wild radish and rye cover crops on weed control and sweet corn yield when used in conjunction with lower-than-recommended herbicide rates. Cover crop treatments included wild radish, rye, and no cover crop, alone and in conjunction with half and full rates of atrazine (0.84 and 1.68 kg ai ha−1) plusS-metolachlor (0.44 and 0.87 kg ai ha−1) applied before sweet corn emergence. Florida pusley, large crabgrass, spreading dayflower, ivyleaf morningglory, and wild radish infested the test sites. Wild radish and rye cover crops without herbicides reduced total weed density by 35 and 50%, respectively, at 4 wk after planting (WAP). Wild radish in conjunction with the full rate of atrazine plusS-metolachlor controlled Florida pusley, large crabgrass, and ivyleaf morningglory better than rye or no cover crop treated with a full herbicide rate in 2004 at Blackville. In 2005, at Blackville, weed control in sweet corn following wild radish cover crop plots alone was not different from that following rye. Wild radish or rye in conjunction with a half or full rate of atrazine andS-metolachlor controlled > 95% Florida pusley, wild radish, and large crabgrass in sweet corn at Tifton during both years. Ten glucosinolates, potential allelopathic compounds, were identified in wild radish, including glucoiberin, progoitrin, glucoraphanin, glucoraphenin, glucosinalbin, gluconapin, glucotropaeolin, glucoerucin, glucobrassicin, and gluconasturtin. Sweet corn yields at Blackville and Tifton following wild radish or rye cover crops were similar between the half and full rates of atrazine plusS-metolachlor. Sweet corn in wild radish or rye cover crop plots without herbicides produced less-marketable ears than herbicide-treated plots, indicating that a combination of cover crops and herbicides are required to optimize yields and to obtain desirable weed control.

and, since 1976, on electncaf packaging analysis. He has "been awarded five US patents. Computer Analysis of Dielectric Waveguides: A Finite-Difference M[ethod EDGARD SCHWEIG, hlH?f13ER,IEEE, AND WILLIAM B. BRIDGES, FELLOW, IEEE .&tract-A method for computing the modes of diel~tric guiding structures based on finite differences is described. The numerrcaf computation program is efficient and can be applied to a wide range of problems. We report here solutions for circular and rectangular dielectric waveguides and compare our solutions with those obtained by other methods. Limitations in the commonly used approximate formulas developed by Marcatili are discussed. I.