A classification of plane and planar 2-trees

We present new functional equations for the species of plane and of planar (in the sense of Harary and Palmer, 1973) 2-trees and some associated pointed species. We then deduce the explicit molecular expansion of these species, i.e a classification of their structures according to their stabilizers. There result explicit formulas in terms of Catalan numbers for their associated generating series, including the asymmetry index series. This work is closely related to the enumeration of polyene hydrocarbons of molecular formula C_nH_n+2.Comment: 26 pages, 14 figure

On Functions Weakly Computable by Pushdown Petri Nets and Related Systems

We consider numerical functions weakly computable by grammar-controlled vector addition systems (GVASes, a variant of pushdown Petri nets). GVASes can weakly compute all fast growing functions $F_\alpha$ for $\alpha<\omega^\omega$, hence they are computationally more powerful than standard vector addition systems. On the other hand they cannot weakly compute the inverses $F_\alpha^{-1}$ or indeed any sublinear function. The proof relies on a pumping lemma for runs of GVASes that is of independent interest

A Genetic Programming Problem Definition Language Code Generator for the EpochX Framework

There are many different genetic programming (GP) frameworks that can be used to implement algorithms to solve a particular optimization problem. In order to use a framework, users need to become familiar with a large numbers of source code before actually implementing the algorithm, adding a learning overhead. In some cases, this can prevent users from trying out different frameworks. This paper discusses the implementation of a code generator in the EpochX framework to facilitate the implementation of GP algorithms. The code generator is based on the GP defini- tion language (GPDL), which is a framework-independent language that can be used to specify GP problems

Pharmaceutical organogels prepared from aromatic amino acid derivatives

Organogels are semi-solid systems in which an organic liquid phase is immobilized by a 3-dimensional network composed of self-assembled gelator molecules. Although there is a large variety of organogel systems, relatively few have been investigated in the field of drug delivery, owing mostly to the lack of information on their biocompatibility and toxicity. In this work, organogelator-biocompatible structures based on aromatic amino acids, namely, tyrosine, tryptophan, and phenylalanine were synthesized by derivatization with aliphatic chains. Their ability to gel an injectable vegetable oil (i.e. safflower oil) and to sustain the release of a model anti-Alzheimer drug (i.e. rivastigmine) was then evaluated. Organogels and molecular packing were characterized by differential scanning calorimetry, rheology analysis, Fourier-transform infrared spectroscopy and X-ray crystallography. The amino acid derivatives were able to gel safflower oil through van der Waals interactions and H-bonds. Tyrosine-derivatives produced the strongest gels while tryptophan was associated with poor gelling properties. The superior gelling ability of tyrosine derivatives could be explained by their well-structured 2-dimensional packing in the network. The addition of an optimal N-methyl-2-pyrrolidone amount to tyrosine gels fluidized the network and allowed their injection through conventional needles. Upon contact with an aqueous medium, the gels formed in situ and released entrapped rivastigmine in a sustained fashion

Resistance to fungicides and streptomycin in Phytophthora parasitica : genetic determinism and use in hybrid determination

Progeny of #Phytophthora parasitica$ derived from the pairings between metalaxyl-resistant MET.1 (A2) carrying homozygous dominant resistance and S1 (A1) wild-type consisted of selfs from each parent and hybrids carrying heterozygous dominant resistance. Similar results were obtained when dimetomorph-resistant DT.1 (A1) carrying homozygous dominant resistance was paired with wild-type S2 (A2). Progeny from the pairing between homozygous Str resistant (A1) to streptomycin and A2 resistant to metalaxyl consisted of selfs and hybrids resistant to either streptomycin or metalaxyl but not both. These results suggest that streptomycin-resistance is cytoplasmic. Progeny from the pairing between homozygous metalaxyl-resistant MET.1 (A1) and homozygous Str (A2) resistant to streptomycin consisted of 28 selfs from A1, 32 selfs form A2, 2 hybrids resulting from the union of A1 oogonium with an A2 antheridium. Progeny from the pairing between homozygous dimetomorph and streptomycin-resistant DT.1 (A1) with wild-type S2 (A2) consisted of 22 selfs A1, 14 selfs A2 and 12 hybrids, two of them resulted from the union A2 oogonium with an A1 antheridium. (Résumé d'auteur

Mise en place d’un laboratoire naturel sur le mont Covey Hill (Québec, Canada)

Le mont Covey Hill héberge des populations de salamandres rares et menacées dont les habitats sont maintenus en partie par\ud l’eau souterraine. Des travaux de recherche multidisciplinaires (UQAM, U. McGill, U. Montréal, IRBV, Centre Brace, SCABRIC et\ud ministères) ont permis de comprendre l’hydrologie ainsi que la répartition et les caractéristiques des habitats de salamandres. Ces projets ont contribué à la mise en place de stations de suivi écologique à long terme et de stations hydrométriques permanentes. En tant que propriétaire de terrains dédiés à la conservation, Conservation de la Nature assure la coordination de ces initiatives. Le mont Covey Hill est aujourd’hui un Laboratoire naturel unique au Québec, dédié à la compréhension intégrée et à long terme d’un écosystème fragile. Cet article a pour objectif de présenter le Laboratoire naturel par une description des recherches en cours et à venir