Inovação institucional, planejamento municipal e organização dos produtores no Nordeste brasileiro: análise comparativa de três experiencias.

O planejamento em nivel municipal mostra-se cada vez mais necessario, no entanto, carece referencias, metodos e instrumentos que permitam a elaboracao de projetos com base em uma negociacao a partir de um dialogo entre os diferentes atores do desenvolvimento. O trabalho apresenta algumas reflexoes sobre a participacao das organizacoes de produtores nos processos de decisao em projetos municipais, a partir do estudo de tres casos caracteristicos da agricultura nordestina: Juazeiro,BA, Pintadas, BA, Taua, CE. O estudo comparativo considera em particular as condicoes de participacao dos produtores nas acoes de planejamento nunicipal e as respectivas estrategias dos diferentes atores envolvidos (produtores, liderancas pliticas, instituicoes, entre outros). As principais conclusoes evidenciam: a condicao da organizacao dos produtres em todo processo de planejamento do desenvolvimento rural municipal; a necessidade e os limites das relacoes de parceria ou de aliancas com outros grupos sociais no contexto nordestino: o papel da intervencao da pesquisa, particularmente na contribuicao para a producao e difusao da informacao, e elaboracao de metodos e instrumentos de apoio a tomada de decisao: a importancia da apropriacao do processo de decisao peloa conjunto dos produtores via espacos de negociacao. A pesquisa agronomica pode ter um papel fundamental junto aos atores locais e as organizacoes de produtores

Organisation des agriculteurs familiaux et developement municipal: trois experiences au Nordeste du Bresil.

Trois expériencie de planification municipale; L´Unité de Planification Agricole de Juazeiro-Bahia - UPAGRO; Tauá-CE; Les stratégies des principaux acteuras;Conditions du dialogue entre acteurs municipaux; Le role de le recherche: elaboration de références et d´intruments d´aide á la décision

Density Matrix Renormalization Group Applied to the Ground State of the XY-Spin-Peierls System

We use the density matrix renormalization group (DMRG) to map out the ground state of a XY-spin chain coupled to dispersionless phonons of frequency $\omega$. We confirm the existence of a critical spin-phonon coupling $_c\propto \omega ^{0.7}$ for the onset of the spin gap bearing the signature of a Kosterlitz-Thouless transition. We also observe a classical-quantum crossover when the spin-Peierls gap $\Delta$ is of order $$. In the classical regime, $\Delta >\omega$, the mean-field parameters are strongly renormalized by non-adiabatic corrections. This is the first application of the DMRG to phonons.Comment: 10 pages, 5 figures. To be published in PR

Estudo de trajetorias de desenvolvimento local e da construcao do espaco rural no Nordeste semi-arido.

O estudo das trajetórias de desenvolvimento é um instrumento elaborado para poder explicitar e representar as transformações dos sistemas de produção e das formas de organização dos atores na escala local. O exemplo da pequena região de Massaroca (Juazeiro-Bahia) apresenta uma ilustração desta metodologia que valoriza a história agrária, a abordagem espacial e apóia-se em entrevistas de agricultores e técnicos locais. Resultados dos estudos de trajetórias de desenvolvimento efetuados em várias local idades do Nordeste Semi-àrido são objeto de uma análise comparativa. Ela é realizada por meio: (I) da interpretação da diversidade ou da semelhança das evoluções em locais distintos para épocas dadas e, (2) da interpretação de evoluções parecidas em locais e momentos diferentes. A comparação evidencia mecanismos diferenciados de evolução das dinâmicas rurais. Ela contribui para o entendimento e a representação das condições e dos processos de diferenciação das situações agrárias. A caracterização das situações estudadas permite a identificação de "tipos de espaço" diferenciados. A cada "tipo" correspondem formas de organização local específicas, estratégias e práticas semelhantes. A análise dos mecanismos de transição entre estas situações leva à identificação de um modelo de evolução das pequenas regiões. Cadeias de evolução dos espaços locais são assim evidenciadas. Finalmente, os autores tratam da vai idade do modelo aplicado ao caso da agricultura familiar do Nordeste Semi-Árido com a perspectiva de identificar as possibilidades de ação de apoio ao desenvolvimento rural

Ecological implications of bovine tuberculosis in African buffalo herds

Following the recent invasion of bovine tuberculosis (BTB) into the Kruger National Park, South Africa, we conducted a study on the maintenance host, African buffalo, to investigate associations between BTB prevalence and calf:cow ratio, age structure, body condition, and endoparasite load. Statistical analyses compared herds of zero, medium (1–40%), and high (\u3e40%) BTB prevalence. To control for ecological variation across the park we collected data in northern, central, and southern regions and restricted some analyses to particular regions of the park. Body condition declined over the course of the 2001 dry season, and buffaloes in the southern region of the park, with the highest BTB prevalence, were in worse condition than buffaloes in the northern region (which receives less annual rainfall but is still virtually BTB-free). Herd-level analyses of the entire park, the south and central regions, and just the southern region all indicated that herds of higher BTB prevalence were in worse condition and lost condition faster through the dry season than herds of lower BTB prevalence. Fecal endoparasite egg counts increased during the dry season and were associated with both decreased body condition and increased BTB prevalence. Although we did not detect any obvious effect of BTB on the age structure of the buffalo population, our findings indicate early symptoms of wider scale BTB-related ecological disturbances: buffalo herds with high BTB prevalence appear more vulnerable to drought (because of a decrease in body condition and an increase in endoparasite load), and because lions selectively kill weak buffaloes their prey base is accumulating a disproportionately high prevalence of BTB, to which lions are susceptible

Contrasting carbonate depositional systems for Pliocene cool-water limestones cropping out in central Hawke's Bay, New Zealand

Pliocene limestone formations in central Hawke's Bay (eastern North Island, New Zealand) accumulated on and near the margins of a narrow forearc basin seaway within the convergent Australia/Pacific plate boundary zone. The active tectonic setting and varied paleogeographic features of the limestone units investigated, in association with probable glacioeustatic sea-level fluctuations, resulted in complex stratigraphic architectures and contrasting types of carbonate accumulation on either side of the seaway. Here, we recognise recurring patterns of sedimentary facies, and sequences and systems tracts bounded by key physical surfaces within the limestone sheets. The facies types range from Bioclastic (B) to Siliciclastic (S) end-members via Mixed (M) carbonate-siliciclastic deposits. Skeletal components are typical cool-water associations dominated by epifaunal calcitic bivalves, bryozoans, and especially barnacles. Siliciclastic contents vary from one formation to another, and highlight siliciclastic-rich limestone units in the western ranges versus siliciclastic-poor limestone units in the eastern coastal hills. Heterogeneities in facies types, stratal patterns, and also in diagenetic pathways between eastern and western limestone units are considered to originate in the coeval occurrence in different parts of the forearc basin of two main morphodynamic carbonate systems over time

Fermi Surface of The One-dimensional Kondo Lattice Model

We show a strong indication of the existence of a large Fermi surface in the one-dimensional Kondo lattice model. The characteristic wave vector of the model is found to be $k_F=(1+\rho )\pi /2$, $\rho$ being the density of the conduction electrons. This result is at first obtained for a variant of the model that includes an antiferromagnetic Heisenberg interaction $J_H$ between the local moments. It is then directly observed in the conventional Kondo lattice $(J_H=0)$, in the narrow range of Kondo couplings where the long distance properties of the model are numerically accessible.Comment: 11 pages, 6 figure

Analyse a posteriori d'une démarche d'observatoire dans un contexte conflictuel : cas de l'irrigation en Charente

La situation de l'irrigation en Poitou-Charentes est emblématique des tensions entre le monde agricole et la société. Pour dépasser ces conflits, un observatoire alliant système d'information et action collective a été mis en place en Charente à l'initiative d'un collectif regroupant responsables politiques, chercheurs et conseillers agricoles. Cet article a pour objectif de restituer l'analyse des différentes perspectives et attentes des acteurs ayant participé à l'élaboration de l'observatoire. L'analyse proposée s'appuie sur une enquête réalisée en 2006 auprès des acteurs concernés. Il en ressort un cadre que nous proposons d'utiliser lors de la conception d'observatoires afin d'expliciter la diversité des attentes des parties prenantes et de faciliter l'élaboration d'un accord préalable à leur mise en ½uvre. / Irrigation in Poitou-Charentes exemplifies the tensions that exist between agriculture and other societal sectors. To overcome these conflicts, a Community Information System (CIS) for the purpose of both data management and community development has been set up in Charente by a group of policymakers, researchers and agricultural advisers. This paper describes our analysis of the differences among participants in the development of this CIS in terms of their points of view and expectations. Drawing on an analysis of a set of interviews conducted with these stakeholders in 2006, we propose a framework for use during the initial design phase of a CIS to make stakeholder expectations explicit and to promote a shared understanding prior to setting up a CIS