[en] Two fast wired operators for carrying out well defined functions and used as peripheral devices for computers are described; one of them is a fast unit for Fourier transform, the other one is large band-pass multibit correlator

[en] The purpose of this work is to elaborate a specific computer able to display the real.time correlation function of two variables represented by two electrical signals. The various functions to be done are dealt with the best suited technology: delays from numerical method, hybrid multiplication, analog integration. This method proved very versatile so that it has been possible to modify the circuits with more performing components without changing the general conception of the whole system. In particular, the bandwidth, which was originally 125 kHz (1966) is now 1 MHz and will be 5 MHz, January 1968. Many results are obtained from the correlator such as: - determination of pulse responses of linear systems (1. and 2. order filters, oscillating circuits); - extraction of signals from noise; - measurement of time and space correlation in a turbulent plasma; - treatment of electro-biological signals. (author)

[en] The spectral density of a signal, which represents its power distribution along the frequency axis, is a function which is of great importance, finding many uses in all fields concerned with the processing of the signal (process identification, vibrational analysis, etc...). Amongst all the possible methods for calculating this function, the correlation method (correlation function calculation + Fourier transformation) is the most promising, mainly because of its simplicity and of the results it yields. The study carried out here will lead to the construction of an apparatus which, coupled with a correlator, will constitute a set of equipment for spectral analysis in real time covering the frequency range 0 to 5 MHz. (author)

[en] Full text: In central and sub-Saharan Africa, the most important constraint to livestock production is trypanosomosis. This tsetse-transmitted disease represents an important risk for about 60 million cattle spread over 7 million km². Several indigenous West African taurine (Bos Taurus) breeds, such as longhorn (N'Dama) cattle are well known to control trypanosome infections. This genetic capability named 'trypanotolerance' results from numerous biological mechanisms most probably under multigenic control, these include the control of the trypanosome infection by a parasitaemia limitation and the control of a severe anemia due to parasite pathogenic effects, both main criteria of trypanotolerance. Past methodologies were not succeeded in identifying the complete pool of genes involved in trypanotolerance. New post genomic biotechnologies, such as transcriptome analyses, are now efficient enough to characterize the full complex of genes involved in the expression of specific biological functions. One is the Serial Analysis of Gene Expression (SAGE) technique which consists in the construction of transcript libraries for the quantitative analysis of entire genes expressed or inactivated at a particular step of cellular activation. We used the SAGE method to compare the total expressed genes during an experimental Trypanosoma congolense infection in four cattle, one N'Dama individual (Bos taurus), one Baoule (Bos taurus) and two zebu (Bos indicus). These animals were infected by the Trypanosoma congolense strain SER/71/STIB/212 (300 trypanosomes per kg of body weight). They were monitored for hematocrite, parasitemia and body weight for five months. The mRNA samples were harvested before infection, at the maximum of parasitemia, at the minimum of hematocrite and at recovery. First, two total mRNA transcripts libraries were constructed from blood white cells of the N'Dama cattle: one at T0 just before the T. congolense experimental infection (T0L) and the other several days later, at the maximum of parasitaemia (MPL). Bioinformatic comparisons in the bovine genomic databases allowed us to identify 4763 sequences Tag, 2281 transcripts and 187 up and down-regulated genes. Among these differentially expressed genes, there were known genes (for instance IgM; IgG, class II BoLA-DQB up-regulated, BoLA class I genes down regulated), several ESTs and unknown functional genes. These results will be compared to the one obtained from the Baoule and the two zebu cattle and will allow identification of the pool of genes involved in trypanotolerant or sensitive character. The knowledge of all identified named or unnamed genes involved in the trypanotolerance control will allow to set up field marker assisted selections. (author)