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A fixed-point implementation of a minimum mean square error (MMSE) based frequency domain (FD) equalizer with soft interference cancellation (SC) is studied. The equalizer additionally processes a priori information about the transmitted symbols and is used for turbo equalization. In this paper, we analyze the quantization and the clipping for different fixed-point representations and modulation schemes. The analysis allows to derive efficient representations for all symbols within the equalizer. This procedure is demonstrated for a generic system configuration featuring a 16-QAM. Finally, a fixed-point implementation in an integrated design environment for FPGAs verifies the theoretical studies and shows the device utilizations for different FPGAs that are embedded in current software defined radios. The results show, that on average 10 bits per symbol are required for a near-optimum equalization performance utilizing less than 8% area of state of the art FPGAs.

The root system of maize consists of the primary root and a variable number of lateral seminal-, crown- and brace roots. Except for the primary root and some minor roots forming at the mesocotyl, all other roots grow out of nodal regions, namely, the embryogenic scutellar node and the underground—as well as the lower above-ground stem nodes. Besides their role in water and nutrient uptake, some of these roots (crown- and brace roots) are essential for the lodging resistance of the plants. This property of the crown roots has now been successfully used for screening a segregating F2 population of a cross between a flint inbred line and an En transposon line. Two allelic root-deficient mutants have been isolated and have been designated rtcs-1 and rtcs-2 for their complete lack of formation of crown- and lateral seminal roots. They survive by the ability of the primary root to support the growth of the developing plant. The monogenic and recessive mutants appear to be affected in an early root-forming function since no primordia are formed either in the case of embryo-borne lateral seminal or stem-derived crown roots. The Rtcs locus could be mapped to the short arm of chromosome 1 with the help of a co-segregating RAPD marker. The effect of the mutation seems to be highly specific since no pleiotropic effects on other parts of the plants have been observed. The formation of adventitious roots can, however, still be induced in the mesocotyl region of the mutant.

Low temperature pulses have two effects on the circadian rhythm exhibited by stem extension rate of green Chenopodium rubrum plants. First, low temperature pulses have the same effect on the phasing of the rhythm as a dark period interrupting continuous light. Second, low temperature pulses stimulate stem extension rate during the 10 hours immediately following the end of the pulse. A difference in temperature between soil and air increases this effect. In any case, it is the change in temperature which is essential and not a specific temperature. Effects of light and temperature on phasing and amplitude of the rhythm explain why the maximal stem growth is observed under normal photo-thermoperiodic conditions, i.e. a high temperature during the photoperiod and a low temperature during the dark period.

Protoplasts, isolated from 10-day-old maize kernels and from a maize embryogenic suspension culture (BMS), were transiently transformed by electroporation with expression plasmids. These plasmids consisted of the CAT gene under the direction of the promoter from a 19-kDa zein gene from maize and of the 35S promoter from Cauliflower Mosaic Virus. Measurement of CAT activity in the transformed protoplasts showed that the zein promoter is only active in protoplasts derived from kernels, while the 35S promoter functions in protoplasts from both kernels and cell culture.