Population genetics of abnormal haemoglobins in Burkina Faso, West Africa

Les fréquences géniques des hémoglobines A (HbA), HbS et HbC, ont été étudiées au Burkina-Faso (BF) ainsi que dans une région avoisinante du Niger : Ayorou. La fréquence d'HbS est plus élevée dans le Sahel (Nord du BF et Ayorou) que dans la zone de savane. L'inverse est trouvé pour HbC. Les résultats essentiels de ce travail sont : (a) la confirmation d'un pic de la fréquence génique de HbC dans le centre du BF (plateau Mossi); (b) une corrélation négative entre les fréquences de HbS et HbC. Cavalli-Sforza et Bodmer ont observé que cette corrélation atteint une intensité significativement différente de celle qui est attendue, par suite de la relation allélique entre HbS et HbC; (c) la comparaison de ces résultats avec les données rassemblées par Livingstone montre une modification de la valeur sélective des différents génotypes au cours des dernières années. Les individus AS ont une valeur sélective plus basse et les AA et SS en ont une plus haute. Nos données sont favorables à l'hypothèse du relâchement partiel de la sélection dans cette région. (Résumé d'auteur

Leptospira interrogans serovar pomona associated with abortion in cattle : isolation methods and laboratory animal histopathology

Leptospira interrogans serovar pomona was successfully isolated from cattle urine in the western Transvaal after an abortion storm had occurred. Direct inoculation of EMJH medium proved the most successful method. The selective agent, 5-fluorouracil, was most effective in controlling contamination when used at the 0,4 mg/ml level. The strain isolated was pathogenic in hamsters, but specific lesions and the leptospirae were seen only where overwhelming infection occurred.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Phase Separation of Rigid-Rod Suspensions in Shear Flow

We analyze the behavior of a suspension of rigid rod-like particles in shear flow using a modified version of the Doi model, and construct diagrams for phase coexistence under conditions of constant imposed stress and constant imposed strain rate, among paranematic, flow-aligning nematic, and log-rolling nematic states. We calculate the effective constitutive relations that would be measured through the regime of phase separation into shear bands. We calculate phase coexistence by examining the stability of interfacial steady states and find a wide range of possible ``phase'' behaviors.Comment: 23 pages 19 figures, revised version to be published in Physical Review

Multifractal stationary random measures and multifractal random walks with log-infinitely divisible scaling laws

We define a large class of continuous time multifractal random measures and processes with arbitrary log-infinitely divisible exact or asymptotic scaling law. These processes generalize within a unified framework both the recently defined log-normal Multifractal Random Walk (MRW) [Bacry-Delour-Muzy] and the log-Poisson "product of cynlindrical pulses" [Barral-Mandelbrot]. Our construction is based on some ``continuous stochastic multiplication'' from coarse to fine scales that can be seen as a continuous interpolation of discrete multiplicative cascades. We prove the stochastic convergence of the defined processes and study their main statistical properties. The question of genericity (universality) of limit multifractal processes is addressed within this new framework. We finally provide some methods for numerical simulations and discuss some specific examples.Comment: 24 pages, 4 figure

The influence of νh11/2 occupancy on the magnetic moments of collective 21+ states in A∼100 fission fragments

AbstractThe magnetic moments of Iπ=21+ states in even–even A∼100 fission fragments have been measured using the Gammasphere array, using the technique of time-integral perturbed angular correlations. The data are interpreted within the context of the interacting boson model (IBA2) leading to the suggestion of a strong νh11/2 component in the deformed 21+ states of this region

Avalanche Dynamics in Evolution, Growth, and Depinning Models

The dynamics of complex systems in nature often occurs in terms of punctuations, or avalanches, rather than following a smooth, gradual path. A comprehensive theory of avalanche dynamics in models of growth, interface depinning, and evolution is presented. Specifically, we include the Bak-Sneppen evolution model, the Sneppen interface depinning model, the Zaitsev flux creep model, invasion percolation, and several other depinning models into a unified treatment encompassing a large class of far from equilibrium processes. The formation of fractal structures, the appearance of $1/f$ noise, diffusion with anomalous Hurst exponents, Levy flights, and punctuated equilibria can all be related to the same underlying avalanche dynamics. This dynamics can be represented as a fractal in $d$ spatial plus one temporal dimension. We develop a scaling theory that relates many of the critical exponents in this broad category of extremal models, representing different universality classes, to two basic exponents characterizing the fractal attractor. The exact equations and the derived set of scaling relations are consistent with numerical simulations of the above mentioned models.Comment: 27 pages in revtex, no figures included. Figures or hard copy of the manuscript supplied on reques