Multifonctionnalité de l’agriculture urbaine à Montréal : étude des discours au sein du programme des jardins communautaires

L’agriculture urbaine peut être une solution pour faire face aux enjeux urbains contemporains. Dans la littérature, on évoque sa pertinence pour contribuer à une sécurité alimentaire des populations urbaines, son offre d’une forme active de loisirs, ses ressources pour répondre aux problématiques environnementales, sa participation au maintien de la santé, sa capacité de permettre le développer des réseaux sociaux, sa participation à l’embellissement et à un aménagement urbain viable et même sa fonction éducative. Toutefois, qu’en est-il du programme des jardins communautaires de la ville de Montréal (Québec, Canada) ? La présente recherche vise à dégager les enjeux que représente l’agriculture urbaine pour les différents acteurs participant au programme. Nous examinons aussi le degré de cohérence entre les fonctions soulevées par les textes officiels de la ville de Montréal et ce qu’en conçoivent les acteurs sur le terrain. Des variables telles que le statut des acteurs (jardiniers, présidents de jardin, animateurs horticoles, agents de développement), ainsi que le quartier urbain d’appartenance sont mobilisées dans l’analyse. Les données de l’étude reposent sur 11 entretiens semi dirigés. Des résultats, il se dégage l’existence d’une agriculture multifonctionnelle dont certaines fonctions sont plus priorisées que d’autres selon les représentations des acteurs. En outre, les enjeux divergent ou convergent selon le statut des acteurs, les arrondissements et les fonctions attribuées à l’agriculture urbaine par la ville dans ses textes. ABSTRACT: Research show that urban agriculture could be a solution to meet modern urban issues, as food security, population health, environmental urban services, social network and popular education. However, is it the case for the cities community gardens program at Montréal (Québec, Canada) ? Based on semi-directed interviews with eleven social actors of this program, this research identifies issues about urban agriculture in Montréal. We also look the consistency between city and urban farmers discourses. Our results show a multidimensional agriculture where some functions are prioritized by actors. We also found that issues highlighted by the city (official documents) could be antagonistic of urban farmers discourses

MULTIFONCTIONNALITÉ DE L'AGRICULTURE URBAINE À MONTRÉAL : ÉTUDE DES DISCOURS SUR LA BASE DU PROGRAMME DES JARDINS COMMUNAUTAIRES

N° ISBN - 978-2-7380-1284-5International audienceUrban agriculture can be a solution for contemporary urban problems. In scientific literature, urban agriculture is demonstrated to contribute to food security of urban populations, to offer leisure activities, to resolve environmental problems, to participate in the preservation of health, to develop social networks, to embellish urban neighbourhoods and to promote viable urban development. In addition it can contribute to the local economy and stimulate educational values. However, what is the real situation in Montreal's program of community gardens? The present study aims to identify the issues raised by urban agriculture for the various actors involved in the program. We also examine the degree of coherence between the multiple functions outlined in the official texts of the city of Montreal and the experience of actors participating in community gardens. Variables such as the status of the actors (gardeners, garden presidents, horticultural facilitators, development agents), and the different urban neighbourhoods are analyzed. The data of the study is based on eleven semi directed interviews. Results illustrate the existence of multifunctional urban agriculture where some functions take priority over others depending on the representation of actors. In summary, the issues differ or converge according to the status of the actors, the neighbourhoods and the urban agriculture functions outlined by the city in its official texts

Agriculture urbaine : un outil multidimensionnel pour le développement des quartiers

Depuis plus de 30 ans différentes expériences en agriculture urbaine (AU) ont eu lieu à Montréal (Québec, Canada). Le programme des jardins communautaires, géré par la Ville, et 6 jardins collectifs, gérés par des organisations communautaires, sont examinés dans le cadre de cet article. Ces expériences visent différents objectifs dont la sécurité alimentaire, la sociabilisation et l’éducation. Ceux-ci évoluent au niveau temporel mais se différencient aussi géographiquement (quartiers). Il en ressort que les initiatives en AU à Montréal s’avère un lieu de production de légumes non négligeable, un lieu de sociabilisation et d’éducation favorisant un développement social individuel et collectifs des quartiers ayant une forte présence de population économique défavorisée. ABSTRACT: For over 30 years, different urban agriculture (UA) experiments have been undertaken in Montreal (Quebec, Canada). The Community Gardening Program, managed by the City, and 6 collective gardens, managed by community organizations, are discussed in this article. These experiments have different objectives, including food security, socialization and education. Although these have changed over time, they have also differed depending on geographic location (neighbourhood). The UA initiatives in Montreal have resulted in the development of a centre with a significant vegetable production and a socialization and education environment that fosters individual and collective social development in districts with a significant economically disadvantaged population. The various approaches attain the established objectives and these are multi-dimensional tools used for the social development of disadvantaged populations

Plasmon scattering from holes: from single hole scattering to Young's experiment

In this article, the scattering of surface plasmon polaritons (SPPs) into photons at holes is investigated. A local, electrically excited source of SPPs using a scanning tunnelling microscope (STM) produces an outgoing circular plasmon wave on a thick (200 nm) gold film on glass containing holes of 250, 500 and 1000 nm diameter. Fourier plane images of the photons from hole-scattered plasmons show that the larger the hole diameter, the more directional the scattered radiation. These results are confirmed by a model where the hole is considered as a distribution of horizontal dipoles whose relative amplitudes, directions, and phases depend linearly on the local SPP electric field. An SPP-Young's experiment is also performed, where the STM-excited SPP-wave is incident on a pair of 1 $\mu$m diameter holes in the thick gold film. The visibility of the resulting fringes in the Fourier plane is analyzed to show that the polarization of the electric field is maintained when SPPs scatter into photons. From this SPP-Young's experiment, an upper bound of $\approx$ 200 nm for the radius of this STM-excited source of surface plasmon polaritons is determined

Bistability in Rayleigh-B\'enard convection with a melting boundary

A pure and incompressible material is confined between two plates such that it is heated from below and cooled from above. When its melting temperature is comprised between these two imposed temperatures, an interface separating liquid and solid phases appears. Depending on the initial conditions, freezing or melting occurs until the interface eventually converges towards a stationary state. This evolution is studied numerically in a two-dimensional configuration using a phase-field method coupled with the Navier-Stokes equations. Varying the control parameters of the model, we exhibit two types of equilibria: diffusive and convective. In the latter case, Rayleigh-B\'enard convection in the liquid phase shapes the solid-liquid front, and a macroscopic topography is observed. A simple way of predicting these equilibrium positions is discussed and then compared with the numerical simulations. In some parameter regimes, we show that multiple equilibria can coexist depending on the initial conditions. We also demonstrate that, in this bi-stable regime, transitioning from the diffusive to the convective equilibrium is inherently a nonlinear mechanism involving finite-amplitude perturbations

Nucleotide, gene and genome evolution : a score to bind them all

National audienceLe document est un résumé étend

Reconstruction of an ancestral Yersinia pestis genome and comparison with an ancient sequence

International audienceBackground: We propose the computational reconstruction of a whole bacterial ancestral genome at the nucleotide scale, and its validation by a sequence of ancient DNA. This rare possibility is offered by an ancient sequence of the late middle ages plague agent. It has been hypothesized to be ancestral to extant Yersinia pestis strains based on the pattern of nucleotide substitutions. But the dynamics of indels, duplications, insertion sequences and rearrangements has impacted all genomes much more than the substitution process, which makes the ancestral reconstruction task challenging. Results: We use a set of gene families from 13 Yersinia species, construct reconciled phylogenies for all of them, and determine gene orders in ancestral species. Gene trees integrate information from the sequence, the species tree and gene order. We reconstruct ancestral sequences for ancestral genic and intergenic regions, providing nearly a complete genome sequence for the ancestor, containing a chromosome and three plasmids. Conclusion: The comparison of the ancestral and ancient sequences provides a unique opportunity to assess the quality of ancestral genome reconstruction methods. But the quality of the sequencing and assembly of the ancient sequence can also be questioned by this comparison

Cylindrical vector beams of light from an electrically excited plasmonic lens

International audienceThe production of cylindrical vector beams from a low-energy, electric, microscale light source is demonstrated both experimentally and theoretically. This is achieved by combining a “plasmonic lens” with the ability to locally and electrically excite propagating surface plasmons on gold films. The plasmonic lens consists of concentric circular subwavelength slits that are etched in a thick gold film. The local excitation arises from the inelastic tunneling of electrons from the tip of a scanning tunneling microscope. We report on the emission of radially polarized beams with an angular divergence of less than ±4°

Invasion of Africa by a single pfcrt allele of South East Asian type

BACKGROUND: Because of its dramatic public health impact, Plasmodium falciparum resistance to chloroquine (CQ) has been documented early on. Chloroquine-resistance (CQR) emerged in the late 1950's independently in South East Asia and South America and progressively spread over all malaria areas. CQR was reported in East Africa in the 1970's, and has since invaded the African continent. Many questions remain about the actual selection and spreading process of CQR parasites, and about the evolution of the ancestral mutant gene(s) during spreading. METHODS: Eleven clinical isolates of P. falciparum from Cambodia and 238 from Africa (Senegal, Ivory Coast, Bukina Faso, Mali, Guinea, Togo, Benin, Niger, Congo, Madagascar, Comoros Islands, Tanzania, Kenya, Mozambique, Cameroun, Gabon) were collected during active case detection surveys carried out between 1996 and 2001. Parasite DNA was extracted from frozen blood aliquots and amplification of the gene pfcrt exon 2 (codon 72–76), exon 4 and intron 4 (codon 220 and microsatellite marker) were performed. All fragments were sequenced. RESULTS: 124 isolates with a sensitive (c76/c220:CVMNK/A) haplotype and 125 isolates with a resistant c76/c220:CVIET/S haplotype were found. The microsatellite showed 17 different types in the isolates carrying the c76/c220:CVMNK/A haplotype while all 125 isolates with a CVIET/S haplotype but two had a single microsatellite type, namely (TAAA)3(TA)15, whatever the location or time of collection. CONCLUSION: Those results are consistent with the migration of a single ancestral pfcrt CQR allele from Asia to Africa. This is related to the importance of PFCRT in the fitness of P. falciparum point out this protein as a potential target for developments of new antimalarial drugs

DHX15-independent roles for TFIP11 in U6 snRNA modification, U4/U6.U5 tri-snRNP assembly and pre-mRNA splicing fidelity

International audienceThe U6 snRNA, the core catalytic component of the spliceosome, is extensively modified post-transcriptionally, with 2’-O-methylation being most common. However, how U6 2’-O-methylation is regulated remains largely unknown. Here we report that TFIP11, the human homolog of the yeast spliceosome disassembly factor Ntr1, localizes to nucleoli and Cajal Bodies and is essential for the 2’-O-methylation of U6. Mechanistically, we demonstrate that TFIP11 knockdown reduces the association of U6 snRNA with fibrillarin and associated snoRNAs, therefore altering U6 2′-O-methylation. We show U6 snRNA hypomethylation is associated with changes in assembly of the U4/U6.U5 tri-snRNP leading to defects in spliceosome assembly and alterations in splicing fidelity. Strikingly, this function of TFIP11 is independent of the RNA helicase DHX15, its known partner in yeast. In sum, our study demonstrates an unrecognized function for TFIP11 in U6 snRNP modification and U4/U6.U5 tri-snRNP assembly, identifying TFIP11 as a critical spliceosome assembly regulator