388 research outputs found
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
AB 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 as . 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
- …