Classifying spaces for families of abelian subgroups of braid groups, RAAGs and graphs of abelian groups

Given a group $G$ and an integer $n\geq 0$ we consider the family $\mathcal{F}_n$ of all virtually abelian subgroups of $G$ of rank at most $n$. In this article we prove that for each $n\ge2$ the Bredon cohomology, with respect to the family $\mathcal{F}_n$, of a free abelian group with rank $k > n$ is nontrivial in dimension $k+n$; this answers a question of Corob Cook, Moreno, Nucinkis and Pasini. As an application, we compute the minimal dimension of a classifying space for the family $\mathcal{F}_n$ for braid groups, right-angled Artin groups, and graphs of groups whose vertex groups are infinite finitely generated virtually abelian groups, for all $n\ge2$. The main tools that we use are the Mayer-Vietoris sequence for Bredon cohomology, Bass-Serre theory, and the L\"uck-Weiermann construction.Comment: 17 pages, 1 figur

Policy options for improving regional fertilizer markets in West Africa:

A primary motivation for this study is to identify a key set of policy options for improving fertilizer markets in West Africa (among Economic Community of West African States member countries) in ways that ultimately will help improve the efficiency of regional markets and lower the transaction costs and fiscal burdens of increasing fertilizer use in the region. Guided by the 2008 fertilizer crisis, many governments are tempted to impose fertilizer subsidies to reduce fertilizer prices. Yet, in an environment riddled with inefficiencies that contribute to the high costs of using fertilizers, the introduction of subsidies only adds more fiscal burden.To carry out the study, we undertook four country case studies to review the key constraints and bottlenecks along the fertilizer supply chain. The countries were Ghana, Mali, Nigeria, and Senegal, and the research included field visits in 2009 and 2010. The current paper is based on the country case study results, complemented by a literature review and analysis of secondary data sources.common fertilizer market, fertilizer use and supply, harmonization of products and regulations, improved technology, policy environment, regional market integration, structure and performance of markets, supply chain,

On the virtually cyclic dimension of normally poly-free groups

In this note we give an upper bound for the virtually cyclic dimension of any normally poly-free group in terms of its length. In particular, this implies that virtually even Artin groups of FC-type admit a finite dimensional model for the classifying space with respect to the family of virtually cyclic subgroups.Comment: 8 pages, comments very welcome

Recent Advances in the Management of Marine Protected Areas in the Philippines

This study presents recent advances in the management of Marine Protected Areas (MPAs) in the Philippine from the mid-1970s, when the first MPA was established, to the present. At present, there are over 1300 established and proposed MPAs in the country. More than 50% of these are less than 10ha in size. As a result, less than 2% of the country’s reef areas are under some level of protection, which is believed to be too low for protective measures to have an impact. In terms of management, only 10-15% of established MPAs are effectively managed. Several challenges are posed by these major shortcomings. Two approaches have recently been initiated to address these. The MPA Support Network (MSN) was recently established to link various efforts and initiatives in managing MPAs in the different regions of the country. There are also recent efforts of developing schemes for truly science-based establishment of MPA networks

RNA Pol II Length and Disorder Enable Cooperative Scaling of Transcriptional Bursting

RNA polymerase II (RNA Pol II) contains a disordered C-terminal domain (CTD) whose length enigmatically correlates with genome size. The CTD is crucial to eukaryotic transcription, yet the functional and evolutionary relevance of this variation remains unclear. Here, we investigate how CTD length and disorder influence transcription. We find that length modulates the size and frequency of transcriptional bursting. Disorder is highly conserved and facilitates CTD-CTD interactions, an ability we show is separable from protein sequence and necessary for efficient transcription. We build a data-driven quantitative model, simulations of which recapitulate experiments and support that CTD length promotes initial polymerase recruitment to the promoter and slows down its release from it and that CTD-CTD interactions enable recruitment of multiple polymerases. Our results reveal how these parameters provide access to a range of transcriptional activity, offering a new perspective for the mechanistic significance of CTD length and disorder in transcription across eukaryotes

Avaliação de indicadores associados à conservação dos recursos hídricos em distintos sistemas de uso da terra para valoração de serviços ambientais.

O objetivo do trabalho é avaliar e comparar indicadores ambientais associados aos recursos hídricos entre distintos sistemas de uso da terra, desde campo e oresta natural passando por sistemas agrosilvopastoril (uma modalidade de sistema agro orestal) e silvicultural até o outro extremo, em monocultura de plantas anuais. A quanti cação e a modelagem desta relação subsidiarão os estudos de valoração dos serviços ambientais prestados nos diferentes usos da terra. ABSTRACT - There is an association between the type and intensity of land use and the quantity and quality of environmental services generated but there are knowledge gaps of the quanti cation of environmental indicators. The objective is to evaluate and compare environmental indicators associated to water resources between different land uses systems from natural eld and forest, silvopastoral and silviculture system to annual crops. The study plots are located in Ponta Grossa, Tibagi River basin, Atlantic Forest biome, Brazil. The quanti cation and modeling these studies will support the valuation of environmental services and hydrological processes in different land uses

Corn yield for silage and grains in different integrated crop-livestock systems.

O objetivo do presente trabalho foi avaliar o efeito de duas doses de adubação nitrogenada (90 e 180 kg de N ha-1, aplicadas na pastagem de inverno), dois sistemas integrados de produção agropecuária (SIPA, com e sem árvores) e cinco posições entre renques arbóreos na qualidade e na produtividade do milho (Zea mays L.) para silagem e grãos. Os tratamentos foram investigados em um delineamento em blocos completos casualizados, com três repetições. As árvores foram plantadas em 2006 num arranjo de 14 x 3 m (atualmente com 158 árvores ha-1), em 6 das 12 parcelas. Ambos SIPAs foram conduzidos com milho durante o verão 2013/2014 e com gado de corte em pastagem anual durante o inverno anterior. O milho foi colhido para silagem no estádio fenológico R5 e para grãos aos 176 dias após a semeadura. As amostras para silagem foram trituradas e armazenadas em mini silos de PVC. Pequenas variações foram observadas na qualidade da silagem em relação a posição entre renques arbóreos. Diferenças entre doses de N no teor em matéria seca, proteína bruta (PB) e produtividade em grãos evidenciam o efeito residual da adubação de inverno. A associação com árvores proporcionou a colheita de uma silagem de melhor qualidade (menor teor de fibra em detergente ácido e maior teor em PB), mas reduziu em 52% a produtividade do milho colhido tanto para silagem como para grãos. Possíveis estratégias são discutidas para reduzir tais perdas

Noah's ark conservation will not preserve threatened ecological communities under climate change

Background: Effective conservation of threatened ecological communities requires knowledge of where climatically suitable habitat is likely to persist into the future. We use the critically endangered Lowland Grassland community of Tasmania, Australia a

Arborização de pastagens com espécies florestais madeireiras: implantação e manejo.

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Biomass allocation in Eucalyptus in monoculture and silvipastoral system.

Resumo. Título em inglês e conteúdo em português