A blind decision feedback equalizer incorporating fixed lag smoothing

Copyright © 2000 IEEEA new type of blind decision feedback equalizer (DFE) incorporating fixed lag smoothing is developed in this paper. The structure is motivated by the fact that if we make full use of the dependence of the observed data on a given transmitted symbol, delayed decisions may produce better estimates of that symbol. To this end, we use a hidden Markov model (HMM) suboptimal formulation that offers a good tradeoff between computational complexity and bit error rate (BER) performance. The proposed equalizer also provides estimates of the channel coefficients and operates adaptively (so that it can adapt to a fading channel for instance) by means of an online version of the expectation-maximization (EM) algorithm. The resulting equalizer structure takes the form of a linear feedback system including a quantizer, and hence, it is easily implemented. In fact, because of its feedback structure, the proposed equalizer shows some similarities with the well-known DFE. A full theoretical analysis of the initial version of the algorithm is not available, but a characterization of a simplified version is provided. We demonstrate that compared to the zero-forcing DFE (ZF-DFE), the algorithm yields many improvements. A large range of simulations on finite impulse response (FIR) channels and on typical fading GSM channel models illustrate the potential of the proposed equalizer.Sylvie Perreau, Langford B. White and Pierre Duhame

A parasitic coevolution since the Miocene revealed by phase-contrast synchrotron X-ray microtomography and the study of natural history collections.

The discovery of a new fossil species of the Caribbeo-Mexican genus Proptomaphaginus (Coleoptera, Leiodidae, Cholevinae) from Dominican amber, associated with a new fossil parasitic fungus in the genus Columnomyces (Ascomycota, Laboulbeniales), triggered an investigation of extant species of Proptomaphaginus and revealed the long-enduring parasitic association between these two genera. This effort resulted in the description of the fossil species †Proptomaphaginus alleni sp. nov., and one fossil and two extant species of Columnomyces, selectively associated with species of Proptomaphaginus: †Columnomyces electri sp. nov. associated with the fossil †Proptomaphaginus alleni in Dominican amber, Columnomyces hispaniolensis sp. nov. with the extant Proptomaphaginus hispaniolensis (endemic of Hispaniola), and Columnomyces peckii sp. nov. with the extant Proptomaphaginus puertoricensis (endemic of Puerto Rico). Based on biogeography, our current understanding is that the Caribbean species of Proptomaphaginus and their parasitic species of Columnomyces have coevolved since the Miocene. This is the first occurrence of such a coevolution between a genus of parasitic fungus and a genus of Coleoptera. The phylogenetic relations among Proptomaphaginus species are also addressed based on a parsimony analysis. Fossil specimens were observed by propagation phase-contrast synchrotron X-ray microtomography (PPC-SRμCT) and extant specimens were obtained through the study of preserved dried, pinned insects, attesting for the importance of (i) technological advancement and (ii) natural history collections in the study of microparasitic relationships

La méthode d'immunofluorescence et l'identification des mycoplasmes. Application au diagnostic de la péripneumonie

L'application de la méthode d'immunofluorescence à l'identification des mycoplasmes et en particulier à la recherche de M. mycoïdes, dans les cultures comme dans les exsudats pathologiques et les lésions, est effectuée par les procédés classiques en utilisant soit des sérums expérimentaux anti-mycoïdes, soit des sérums de bovins malades naturels. Les résultats montrent que ce procédé est spécifique et que des réactions croisées ne sont pas à craindre avec les autres espèces de mycoplasmes rencontrées chez les ruminants si l'on s'entoure d'un minimum de précautions. Les conditions techniques de ces examens font l'objet d'une description détaillé

Isolement d’un mycoplasme du groupe Mycoplasma mycoïdes var. capri à partir d’un lait de mammite chez la Chèvre

A partir du lait de chèvres atteintes d’un mammite contagieuse grave, associée à des arthrites, une souche de mycoplasme est isqlée ; les procédés actuels d’identification permettent, sans doute aucun, de la classer dans un groupe de souches considérées comme représentatives de l’espèce M. mycoides var. capri