Voyage de Ch. Alluaud et R. Jeannel en Afrique Orientale (1911-1912) (Gryllidae)

Ainsi que je l'ai déjà indiqué pour les Mantides , l'Afrique Orientale ne peut en aucune façon être considérée comme une région zoogéographique délimitée. Le Catalogue que je donne ci-dessous n'a donc d'autre but que de faire connaître les espèces récoltées dans la région, et par là même, de faciliter les recherches et les déterminations futures.Peer reviewe

Les divisions du genre Gryllus basees sur l'étude de l'appareil copulateur (Orth. Gryllidae)

13 láminasDans un travail récent (1954), j'ai fait ressortir les difficultés que les systématiciens recontrent pour séparer les nombreuses espèces du genre Gryllus. J'ai indiqué que, parmi les caractères utilisés dans ce but, l'appareil copulateur du /riffle semble étre le plus valabie et le plus constant. Toutefois, j'indiquais en méme temps qu'il ne semblait pas qu'on puisse demander davantage à ce caractére et en particulier, qu'il ne permettait pas d'établir des divisions d'ordre générique. Je dois revenir aujourd'hui sur cette question. L'étude que j'ai poursuivie de l'organe copulateur des Gryllus m'a permis d'examiner plus de la moitié des quelque deux cents espéces actuellement classées dans ce genre. La comparaison des nombreuses formes étudiées amène en effet à les grouper en plusieurs catégories assez nettement caractérisées. Ce groupement permet de confirmer les affinttés qui avaient été mises en valeur par des méthodes différentes. Le cas le plus typique est celui qui permet de rapprocher par un caractère anatomique les espéces américaines du genre Gryllus et deux de nos espèces françaises (Gryllus campestris et G. bimaculatus) dont les affinités étroites avaient déja été mises en évidence par les résultats des croisements interspécifiques réalisés par Mlle. Cousin.Peer reviewe

Opportunity for development or necessary nuisance? The case for viewing working with interpreters as a bonus in therapeutic work

This paper explores the central role a language interpreter can play in the process of the therapeutic relationship. Although others have described the changes to the therapeutic dyad that the presence of a third party (an interpreter) brings, little attention has been paid to the advantages and additional opportunities of this altered therapeutic situation. This paper details these gains and further argues that clinicians who are willing to gain experience of working with interpreters will find that benefits accrue at the micro and macro levels: at the micro level, through enhancement of their work with individual non English speaking clients, and at the macro level through learning about different cultural perspectives, idioms of distress and the role of language in the therapeutic endeavour. This is in addition to developing skills to fulfil legal and professional requirements relating to equity of service provision. Some ideas are offered to explain the negative slant than runs throughout the literature in this area and tends to colour the overall discussion of therapeutic work with interpreters and, before the final section, makes some specific suggestions which may help maximise the gains possible in such work while reducing difficulties

Refined Simulations of the Reaction Front for Diffusion-Limited Two-Species Annihilation in One Dimension

Extensive simulations are performed of the diffusion-limited reaction A$+$B$\to 0$ in one dimension, with initially separated reagents. The reaction rate profile, and the probability distributions of the separation and midpoint of the nearest-neighbour pair of A and B particles, are all shown to exhibit dynamic scaling, independently of the presence of fluctuations in the initial state and of an exclusion principle in the model. The data is consistent with all lengthscales behaving as $t^{1/4}$ as $t\to\infty$. Evidence of multiscaling, found by other authors, is discussed in the light of these findings.Comment: Resubmitted as TeX rather than Postscript file. RevTeX version 3.0, 10 pages with 16 Encapsulated Postscript figures (need epsf). University of Geneva preprint UGVA/DPT 1994/10-85

The lattice Boltzmann advection-diffusion model revisited

Advection-diffusion processes can be simulated by the Lattice Boltzmann method. Two formulations have been proposed in the literature. We show that they are not fully correct (only first order accurate). A new formulation is proposed, which is shown to produce better results, both from the point of view of the Chapman-Enskog expansion or when comparing simulations with an exact time-dependent solution of the advection-diffusion equatio

Les Sauterelles migratrices : utilisation des données biologiques dans la lutte contre ces insectes

Chopard Lucien. Les Sauterelles migratrices : utilisation des données biologiques dans la lutte contre ces Insectes. In: La Terre et La Vie, Revue d'Histoire naturelle, tome 4, n°9, 1934. pp. 323-330

Localization-delocalization transition of a reaction-diffusion front near a semipermeable wall

The A+B --> C reaction-diffusion process is studied in a system where the reagents are separated by a semipermeable wall. We use reaction-diffusion equations to describe the process and to derive a scaling description for the long-time behavior of the reaction front. Furthermore, we show that a critical localization-delocalization transition takes place as a control parameter which depends on the initial densities and on the diffusion constants is varied. The transition is between a reaction front of finite width that is localized at the wall and a front which is detached and moves away from the wall. At the critical point, the reaction front remains at the wall but its width diverges with time [as t^(1/6) in mean-field approximation].Comment: 7 pages, PS fil

Pair Contact Process with Diffusion: Failure of Master Equation Field Theory

We demonstrate that the `microscopic' field theory representation, directly derived from the corresponding master equation, fails to adequately capture the continuous nonequilibrium phase transition of the Pair Contact Process with Diffusion (PCPD). The ensuing renormalization group (RG) flow equations do not allow for a stable fixed point in the parameter region that is accessible by the physical initial conditions. There exists a stable RG fixed point outside this regime, but the resulting scaling exponents, in conjunction with the predicted particle anticorrelations at the critical point, would be in contradiction with the positivity of the equal-time mean-square particle number fluctuations. We conclude that a more coarse-grained effective field theory approach is required to elucidate the critical properties of the PCPD.Comment: revtex, 8 pages, 1 figure include