Flexibility in the length of convolutions computed using Fourier-like fast transform algorithms

An efficient method of achieving flexibility in the length of discrete convolutions, computed using Fourier and Fourier-like fast transform algorithms, is described. Then this method is extended to discrete multidimensional convolutions computed using polynomial transforms.     

Power spectral densities of bit and word-interleaved line-coded channels for Gbit/s transmission

General formulas are presented for the power spectral densities (PSDs) of bit and word-interleaved line-coded digital signals, which are useful in the design of Gbit/s transmission systems. It is shown that word interleaving introduces very little spectral degradation for commonly used line codes, whereas the effects of bit-interleaving, though marked, are simply quantified. These predictions are confirmed by calculations of the PSDs using Monte Carlo simulations.<>     

DFT processing of variable length sequences

A method is presented for the frequency domain digital processing of signals of various lengths using a transform processor or program designed for a particular length. The proposed system employs a transform processor based on any algorithm and a shift register with a few feedforward connections. The method is especially useful in digital processing applications that involve two-dimensional signals. It can be applied for the processing of signals using the conventional discrete Fourier transform or number theoretic transforms.     

Cascadable one/two-dimensional digital convolver

An architecture and a design for a high-speed CMOS digital convolver which can be used for real-time one-dimensional (1-D) and two-dimensional (2-D) signal processing are presented. In the 2-D mode this device can be used to convolve 10-bit image data with a 3×3 or 2×5 2-D eight-bit-per-coefficient impulse response at 20 M samples/s throughput. In 1-D applications it can be used as a ten-tap finite-impulse response (FIR) filter. Devices can be cascaded to increase the order of the convolution reference in both dimensions     

Efficient transforms for multidimensional convolutions

A discrete transform is described for the computation of multidimensional convolutions often encountered in image and array-processing applications. The transform is free of multiplications in all dimensions but one, and has all advantages claimed by the d.f.t. methods.     

Multidimensional fast-Fourier-transform algorithm

A multidimensional fast-Fourier-transform algorithm is developed for the computation of multidimensional Fourier and Fourier-like discrete transforms; it has considerably less multiplications than the conventional fast-Fourier-transform methods.     

Carriage of SDH over satellite systems

This paper examines the potential of satellite systems to carry synchronous digital hierarchy (SDH) transmissions and proposes a possible earth-station architecture capitalizing on the benefits that SDH equipment offers. It is shown that a range of SDH multiplexing rates are viable over satellite and that multi-destination operation of satellite systems is facilitated by using the inherent features of the SDH. The use of STM-1 (155 Mbit/s) and sub-STM-1 transmission rates as transmission sections along with appropriate integration of the multiplexing and modem equipment would:. (a) enable SDH path continuity between earth-stations, allowing the satellite network to be integrated with managed terrestrial networks to form global managed transmission platforms. (b) provide bandwidth and equipment savings at earth-stations. Several technical issues relating to SDH operation over satellite systems are considered and SDH pointer corruption is examined in some detail.     

Thyroid hormone and follicle-stimulating hormone regulate Müllerian-inhibiting substance messenger ribonucleic acid expression in cultured neonatal rat Sertoli cells

Thyroid hormone is a major regulator of Sertoli cell development, and the present study sought to determine the role of T3 in Müllerian-inhibiting substance (MIS) messenger RNA (mRNA) expression. MIS, a Sertoli cell secretory protein that induces Müllerian duct regression and also may be critical for germ and Leydig cell development, is maximal perinatally, then decreases as Sertoli cells mature. The fall in MIS mRNA expression is delayed by hypothyroidism in vivo, indicating that T3 could regulate MIS mRNA. However, understanding of the hormonal regulation of MIS has been limited due partly to the lack of a primary Sertoli cell culture system in which sustained expression of MIS or its mRNA can be obtained. We have developed a Sertoli cell culture system for examining hormonal regulation of MIS mRNA. We then tested the effects of T3 and/or FSH treatment on MIS mRNA levels in this new system. Initial studies indicated that MIS mRNA production by 5-day-old rat Sertoli cells was minimal in vitro. Therefore, Sertoli cells from 2-day-old rats were cultured for 2 or 4 days. After 2 days in vitro, steady state MIS mRNA levels were decreased to 36% of the levels seen in freshly isolated Sertoli cells from 2-day-old rats. However, by day 4 of culture, steady state MIS mRNA production had recovered to 67% of that seen in freshly isolated 2-day-old Sertoli cells, which closely paralleled the decrease seen in MIS production in vivo from days 2-6. MIS mRNA levels were decreased 53%, 64%, and 86% in cultures treated with 0.01, 0.1, and 1.0 nM T3 (P < 0.05), respectively. This decrease in Sertoli cell MIS mRNA did not reflect a nonspecific effect on cell viability and/or activity, as shown by a dose-responsive increase in inhibin-alpha mRNA in these same cultures. FSH (2.5-100 ng/ml) also produced a dose-responsive decrease in MIS mRNA levels, and FSH and T3 together had an additive inhibitory effect on MIS mRNA levels, indicating that these hormones may act through distinct mechanisms. In summary, this is the first primary culture system in which sustained MIS mRNA production can be demonstrated, and it should prove useful for understanding the regulation of MIS in developing Sertoli cells. In addition, T3 and FSH are major regulators of the postnatal decrease in MIS production by the rat Sertoli cell, and these hormones may act through separate pathways.